# KokonutUI - Full Documentation

> Collection of stunning UI components, free and open source, built with Next.js, React, Tailwind CSS, and Motion.

Every documentation page, concatenated. Index: https://kokonutui.com/llms.txt

---
# Agents
> Use Kokonut UI with Claude Code, Cursor, VS Code or Codex. Connect the shadcn MCP server, add a rules file, and give your agent the docs as Markdown.

Source: https://kokonutui.com/docs/agents

Kokonut UI is a shadcn/ui registry, so any agent that can run the shadcn CLI can install its components. Ask for a component by name, or describe what you need, and the agent finds it, installs it with its dependencies, and edits it in your codebase like any other file.

To have an agent do the whole setup, give it this prompt:

```text
Set up Kokonut UI in this project by following https://kokonutui.com/setup.md
```

If you are an agent setting up Kokonut UI, follow https://kokonutui.com/setup.md. Otherwise, follow the steps below.

## Add the registry

Agents install from the `@kokonutui` namespace, so add it to your `components.json` once. If you don't have one yet, run `shadcn init` first, as shown in [Installation](/docs).

```json title="components.json"
{
  "registries": {
    "@kokonutui": "https://kokonutui.com/r/{name}.json"
  }
}
```

## Connect your editor

The [shadcn MCP server](https://ui.shadcn.com/docs/mcp) lets your agent list, search and install components from any registry in `components.json`. One command sets it up for your editor:

### Claude Code

```bash
npx shadcn@latest mcp init --client claude
```

Or add it by hand to `.mcp.json`:

```json title=".mcp.json"
{
  "mcpServers": {
    "shadcn": {
      "command": "npx",
      "args": ["shadcn@latest", "mcp"]
    }
  }
}
```

Restart Claude Code, then run /mcp to check that shadcn is connected.

### Cursor

```bash
npx shadcn@latest mcp init --client cursor
```

Add to Cursor: cursor://anysphere.cursor-deeplink/mcp/install?name=shadcn&config=eyJjb21tYW5kIjoibnB4IiwiYXJncyI6WyJzaGFkY25AbGF0ZXN0IiwibWNwIl19

Or add it by hand to `.cursor/mcp.json`:

```json title=".cursor/mcp.json"
{
  "mcpServers": {
    "shadcn": {
      "command": "npx",
      "args": ["shadcn@latest", "mcp"]
    }
  }
}
```

Turn the server on in Cursor Settings, under MCP.

### VS Code

```bash
npx shadcn@latest mcp init --client vscode
```

Add to VS Code: vscode:mcp/install?%7B%22name%22%3A%22shadcn%22%2C%22command%22%3A%22npx%22%2C%22args%22%3A%5B%22shadcn%40latest%22%2C%22mcp%22%5D%7D

Or add it by hand to `.vscode/mcp.json`:

```json title=".vscode/mcp.json"
{
  "servers": {
    "shadcn": {
      "command": "npx",
      "args": ["shadcn@latest", "mcp"]
    }
  }
}
```

Open .vscode/mcp.json and click Start next to the shadcn server.

### Codex

```bash
npx shadcn@latest mcp init --client codex
```

Or add it by hand to `~/.codex/config.toml`:

```toml title="~/.codex/config.toml"
[mcp_servers.shadcn]
command = "npx"
args = ["shadcn@latest", "mcp"]
```

Restart Codex. It reads the server from your global config.

Any other client that speaks the Model Context Protocol works too: point it at `npx shadcn@latest mcp`.

## Ask your agent

Restart your editor, then ask in plain language. Each prompt copies.

- "Show me every component in the @kokonutui registry"
- "Add @kokonutui/particle-button to my project"
- "Add an AI chat input with a model picker to the home page"
- "Build a pricing section with @kokonutui components"

The agent installs a component's shadcn/ui primitives (like `button` or `textarea`) and npm packages (like `motion` or `lucide-react`) along with it, exactly as the CLI does.

## Add a rules file

A short rules file tells your agent to check Kokonut UI before building a component from scratch, and to install rather than paste code. Save it in your project under the file name shown for your editor.

### Claude Code: `CLAUDE.md`

```markdown title="CLAUDE.md"
# Kokonut UI

This project installs components from Kokonut UI, a shadcn/ui registry.
The registry is set in components.json as "@kokonutui".

- Before building an animated or interactive component from scratch, check
  Kokonut UI: https://kokonutui.com/llms.txt lists every component with a
  one-line description.
- Install with the shadcn CLI, never by pasting code:
  npx shadcn@latest add @kokonutui/<name>
  It writes components/kokonutui/<name>.tsx and installs its dependencies.
- Installed components are project code. Edit them in place rather than
  wrapping them.
- Any docs page is available as Markdown, with the full source, by adding
  .md to its URL, e.g. https://kokonutui.com/docs/buttons/particle-button.md
```

### Cursor: `.cursor/rules/kokonutui.mdc`

```markdown title=".cursor/rules/kokonutui.mdc"
---
description: Installing and editing Kokonut UI components
alwaysApply: false
---

# Kokonut UI

This project installs components from Kokonut UI, a shadcn/ui registry.
The registry is set in components.json as "@kokonutui".

- Before building an animated or interactive component from scratch, check
  Kokonut UI: https://kokonutui.com/llms.txt lists every component with a
  one-line description.
- Install with the shadcn CLI, never by pasting code:
  npx shadcn@latest add @kokonutui/<name>
  It writes components/kokonutui/<name>.tsx and installs its dependencies.
- Installed components are project code. Edit them in place rather than
  wrapping them.
- Any docs page is available as Markdown, with the full source, by adding
  .md to its URL, e.g. https://kokonutui.com/docs/buttons/particle-button.md
```

### VS Code: `.github/copilot-instructions.md`

```markdown title=".github/copilot-instructions.md"
# Kokonut UI

This project installs components from Kokonut UI, a shadcn/ui registry.
The registry is set in components.json as "@kokonutui".

- Before building an animated or interactive component from scratch, check
  Kokonut UI: https://kokonutui.com/llms.txt lists every component with a
  one-line description.
- Install with the shadcn CLI, never by pasting code:
  npx shadcn@latest add @kokonutui/<name>
  It writes components/kokonutui/<name>.tsx and installs its dependencies.
- Installed components are project code. Edit them in place rather than
  wrapping them.
- Any docs page is available as Markdown, with the full source, by adding
  .md to its URL, e.g. https://kokonutui.com/docs/buttons/particle-button.md
```

### Codex: `AGENTS.md`

```markdown title="AGENTS.md"
# Kokonut UI

This project installs components from Kokonut UI, a shadcn/ui registry.
The registry is set in components.json as "@kokonutui".

- Before building an animated or interactive component from scratch, check
  Kokonut UI: https://kokonutui.com/llms.txt lists every component with a
  one-line description.
- Install with the shadcn CLI, never by pasting code:
  npx shadcn@latest add @kokonutui/<name>
  It writes components/kokonutui/<name>.tsx and installs its dependencies.
- Installed components are project code. Edit them in place rather than
  wrapping them.
- Any docs page is available as Markdown, with the full source, by adding
  .md to its URL, e.g. https://kokonutui.com/docs/buttons/particle-button.md
```

## Docs for agents

Every page on this site is also served as Markdown, so an agent can read the docs without a browser. Each component page includes its install command and full source.

- `https://kokonutui.com/setup.md`: Setup steps written for an agent: registry, MCP server and rules file. The setup prompt points here.
- `https://kokonutui.com/llms.txt`: Index of every docs page, with a one-line description and a link to its Markdown.
- `https://kokonutui.com/llms-full.txt`: Every docs page in one file, component source included. Large; for agents that read it once.
- `https://kokonutui.com/docs/<page>.md`: Any docs page as Markdown, with its install command and full source. The Copy Markdown button on each page copies the same text.
- `https://kokonutui.com/r/registry.json`: The shadcn registry index: every component with its dependencies and files.
- `https://kokonutui.com/r/<name>.json`: One component's registry item, the file the CLI and the MCP server install from.

At the top of every page, **Copy Markdown** copies the page for a chat, and **Open** sends it to ChatGPT, Claude or Cursor.


---

# Changelog
> New and updated Kokonut UI components, release by release, with a link to each component and its pull request.

Source: https://kokonutui.com/docs/changelog

## October 14, 2026

**New components**

- [Notification Stack](https://kokonutui.com/docs/cards/notification-stack.md) (Cards, [#39](https://github.com/kokonut-labs/kokonutui/pull/39)): Stacked notifications that fan out on hover and swipe away, built with React and Tailwind CSS.
- [Detent Dial](https://kokonutui.com/docs/inputs/detent-dial.md) (Inputs, [#40](https://github.com/kokonut-labs/kokonutui/pull/40)): Rotary knob that clicks from notch to notch and coasts when flicked, built with React and Motion.
- [Wheel Picker](https://kokonutui.com/docs/inputs/wheel-picker.md) (Inputs, [#41](https://github.com/kokonut-labs/kokonutui/pull/41)): iOS-style 3D drum picker with flick momentum, built with React and Motion.
- [Topo Background](https://kokonutui.com/docs/backgrounds/topo-background.md) (Backgrounds, [#46](https://github.com/kokonut-labs/kokonutui/pull/46)): A living contour map that drifts, rises under the cursor and ripples on click, built with React and Canvas.
- [Pull Cord](https://kokonutui.com/docs/buttons/pull-cord.md) (Buttons, [#47](https://github.com/kokonut-labs/kokonutui/pull/47)): A lamp switch you pull on a swinging cord, built with React and a rope simulation.
- [Liquid Gauge](https://kokonutui.com/docs/cards/liquid-gauge.md) (Cards, [#50](https://github.com/kokonut-labs/kokonutui/pull/50)): A usage meter filled with liquid that sloshes, ripples and bubbles, built with React and a wave simulation.
- [Activity Terrain](https://kokonutui.com/docs/cards/activity-terrain.md) (Cards, [#51](https://github.com/kokonut-labs/kokonutui/pull/51)): A contribution heatmap that tilts up into a 3D terrain you can turn, built with React and canvas.
- [Receipt Printer](https://kokonutui.com/docs/cards/receipt-printer.md) (Cards, [#52](https://github.com/kokonut-labs/kokonutui/pull/52)): A receipt that prints line by line, then tears off and falls when you pull it, built with React.
- [Liquid Slider](https://kokonutui.com/docs/inputs/liquid-slider.md) (Inputs, [#53](https://github.com/kokonut-labs/kokonutui/pull/53)): A vertical slider you fill like a glass, with a sloshing surface and rising bubbles.
- [Signature Pad](https://kokonutui.com/docs/inputs/signature-pad.md) (Inputs, [#54](https://github.com/kokonut-labs/kokonutui/pull/54)): A signature field with a sprung pen tip, speed-weighted ink and SVG output.
- [Tear Button](https://kokonutui.com/docs/buttons/tear-button.md) (Buttons, [#55](https://github.com/kokonut-labs/kokonutui/pull/55)): A confirm button you tear off like a ticket stub, hole by hole.
- [Bell Button](https://kokonutui.com/docs/buttons/bell-button.md) (Buttons, [#56](https://github.com/kokonut-labs/kokonutui/pull/56)): A subscribe button whose bell swings and rings, with a clapper that really strikes.
- [Plucked Text](https://kokonutui.com/docs/texts/plucked-text.md) (Texts, [#57](https://github.com/kokonut-labs/kokonutui/pull/57)): A headline sitting on a string you can pluck, strum and let ring, built with React and real string physics.
- [Marking Menu](https://kokonutui.com/docs/navigation/marking-menu.md) (Navigation, [#58](https://github.com/kokonut-labs/kokonutui/pull/58)): A radial menu you hold to open or flick to pick blind, built with React and Motion.
- [Drape Background](https://kokonutui.com/docs/backgrounds/drape-background.md) (Backgrounds, [#59](https://github.com/kokonut-labs/kokonutui/pull/59)): A pleated curtain in a breeze that you can push and pull, built with React, WebGL and a cloth simulation.
- [Dot Field](https://kokonutui.com/docs/backgrounds/dot-field.md) (Backgrounds, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): A halftone dot membrane that ripples behind a swipe and rings out from a click, built with React and Canvas.

**Improved**

- [Flick Card](https://kokonutui.com/docs/cards/card-flip.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Flick Card: drag or flick it to spin, with thickness and light that follow the angle.
- [Throw Deck](https://kokonutui.com/docs/cards/card-stack.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Throw Deck: throw the top card off and it tucks back under the pile.
- [Momentum Rail](https://kokonutui.com/docs/cards/carousel-cards.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Momentum Rail: drag with momentum and cover-flow depth from scroll.
- [Now Playing](https://kokonutui.com/docs/cards/liquid-glass-card.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Now Playing: a spinning disc you turn to scrub the track.
- [Widget Grid](https://kokonutui.com/docs/cards/bento-grid.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Widget Grid: pick up, reorder and resize widgets by pointer or keyboard.
- [Dynamic Text](https://kokonutui.com/docs/texts/dynamic-text.md) (Texts, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Morph Text: letters travel, fall and land between strings, with decode and cycle modes.
- [Glitch Text](https://kokonutui.com/docs/texts/glitch-text.md) (Texts, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Signal Text: flat text with sliced band glitches, on idle, hover or change.
- [Extruded Text](https://kokonutui.com/docs/texts/swoosh-text.md) (Texts, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Extruded Text: 3D letters lit by the cursor that sink like keycaps.
- [Wind](https://kokonutui.com/docs/backgrounds/flow-field.md) (Backgrounds, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Wind: monochrome streamlines that part around the cursor and swirl in its wake.
- [Tool Dock](https://kokonutui.com/docs/navigation/toolbar.md) (Navigation, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Tool Dock: a draggable editor dock with tooltips, shortcuts and tool flyouts.
- [Swipe Tabs](https://kokonutui.com/docs/navigation/smooth-tab.md) (Navigation, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Swipe Tabs: swipe the panel and the indicator follows your finger.
- [Split Nav](https://kokonutui.com/docs/navigation/morphic-navbar.md) (Navigation, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Split Nav: the bar splits around the active link and you can scrub across it.
- [Account Menu](https://kokonutui.com/docs/navigation/profile-dropdown.md) (Navigation, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Account Menu: the card morphs into its menu, with account switching and hold to sign out.
- [Command Palette](https://kokonutui.com/docs/navigation/action-search-bar.md) (Navigation, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Rebuilt as Command Palette: nested pages, fuzzy matching and instant keyboard use.
- [Avatar Picker](https://kokonutui.com/docs/inputs/avatar-picker.md) (Inputs, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Faces generated from your name, on a 3D coin you can flick or shuffle.
- [Currency Transfer](https://kokonutui.com/docs/cards/currency-transfer.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Odometer amounts, a chip that carries the money across, and a progress arc.
- [Typing Text](https://kokonutui.com/docs/texts/type-writer.md) (Texts, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): A caret that blinks only when idle, select-to-delete, and optional typos.
- [Apple Activity Card](https://kokonutui.com/docs/cards/apple-activity-card.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Numbers count up with the rings, and rings can go past 100%.
- [Notification Stack](https://kokonutui.com/docs/cards/notification-stack.md) (Cards, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Released cards spring back or fly away with your finger's speed.
- [Topo Background](https://kokonutui.com/docs/backgrounds/topo-background.md) (Backgrounds, [#67](https://github.com/kokonut-labs/kokonutui/pull/67)): Elevation labels on the contour lines.
- [Background Paths](https://kokonutui.com/docs/backgrounds/background-paths.md) (Backgrounds, [#48](https://github.com/kokonut-labs/kokonutui/pull/48)): Rebuilt as one flowing ribbon of lines that part around the cursor.
- [Shape Hero](https://kokonutui.com/docs/backgrounds/shape-hero.md) (Backgrounds, [#49](https://github.com/kokonut-labs/kokonutui/pull/49)): Rebuilt around a pile of shapes you can drag and throw.
- [AI Voice](https://kokonutui.com/docs/ai/ai-voice.md) (AI, [#60](https://github.com/kokonut-labs/kokonutui/pull/60)): A scrolling waveform, and a take you review before sending.
- [AI Input Selector](https://kokonutui.com/docs/ai/ai-prompt.md) (AI, [#61](https://github.com/kokonut-labs/kokonutui/pull/61)): Attachment chips, slash commands, and Stop while it replies.
- [AI State Loading](https://kokonutui.com/docs/ai/ai-loading.md) (AI, [#62](https://github.com/kokonut-labs/kokonutui/pull/62)): Agent steps with a live log, a step rail and timings.
- [AI Text Loading](https://kokonutui.com/docs/ai/ai-text-loading.md) (AI, [#63](https://github.com/kokonut-labs/kokonutui/pull/63)): A letter wave instead of a gradient shimmer.
- [Particle Button](https://kokonutui.com/docs/buttons/particle-button.md) (Buttons, [#25](https://github.com/kokonut-labs/kokonutui/pull/25)): Calls your onClick and onSuccess, and keeps particles inside the button.
- [Gradient Button](https://kokonutui.com/docs/buttons/gradient-button.md) (Buttons, [#27](https://github.com/kokonut-labs/kokonutui/pull/27)): Correct light and dark themes, and renders its children and icon.

**Across the library**

- Every component now works right after shadcn add, without the docs site's styles. ([#32](https://github.com/kokonut-labs/kokonutui/pull/32))
- Fixed components whose main feature didn't work. ([#33](https://github.com/kokonut-labs/kokonutui/pull/33))
- Keyboard, focus and screen reader fixes, and reduced motion support, across the library. ([#34](https://github.com/kokonut-labs/kokonutui/pull/34), [#35](https://github.com/kokonut-labs/kokonutui/pull/35), [#36](https://github.com/kokonut-labs/kokonutui/pull/36))


---

# Installation
> Install KokonutUI components in any React or Next.js project with the shadcn CLI, using namespaces or direct registry URLs. No extra setup required.

Source: https://kokonutui.com/docs

To have an agent do the whole setup, give it this prompt:

```text
Set up Kokonut UI in this project by following https://kokonutui.com/setup.md
```

If you are an agent setting up Kokonut UI, follow https://kokonutui.com/setup.md. Otherwise, follow the steps below.

## Add the registry

Kokonut UI is a shadcn/ui registry. The shadcn CLI reads its configuration from `components.json`; if your project doesn't have one yet, create it:

```bash
npx shadcn@latest init
```

Then add the `@kokonutui` namespace to it, so components install by name:

```json title="components.json"
{
  "registries": {
    "@kokonutui": "https://kokonutui.com/r/{name}.json"
  }
}
```

> **Copying code instead?**
>
> `components.json` is only needed for the CLI. If you copy a component's source by hand, you can skip it, but you'll have to install its dependencies yourself.

## Install the utilities

Components are styled with [Tailwind CSS v4](https://tailwindcss.com/docs/installation/framework-guides/nextjs), so make sure it's set up. Most of them also use the `cn` helper:

```bash
npx shadcn@latest add https://kokonutui.com/r/utils.json
```

## Add a component

Name the component. The CLI writes it to `components/kokonutui/` and installs what it needs, such as [lucide-react](https://lucide.dev/guide/installation) icons, [shadcn/ui](https://ui.shadcn.com/) primitives and `motion`:

```bash
npx shadcn@latest add @kokonutui/particle-button
```

Then use it like any component in your project:

```tsx title="app/page.tsx"
import ParticleButton from "@/components/kokonutui/particle-button";

export default function Page() {
  return <ParticleButton />;
}
```

Each component page lists the packages it installs above its demo. Prefer the CLI over copying the source: it brings every file and dependency the component needs.

## Use an AI agent

Claude Code, Cursor, VS Code and Codex can find and install components for you through the shadcn MCP server. See [Agents](/docs/agents) to connect your editor and add a rules file.

## Monorepos

In a monorepo, pass the workspace the component belongs to with `-c`:

```bash
npx shadcn@latest add @kokonutui/particle-button -c ./apps/www
```


---

# AI Input Search
> AI search chat input with toggleable web search mode, file attachment and auto-resizing textarea. Built with React, Tailwind CSS and Motion.

Source: https://kokonutui.com/docs/ai/ai-input-search

## Installation

```bash
npx shadcn@latest add @kokonutui/ai-input-search
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: AI Input Search
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { Globe, Paperclip, Send } from "lucide-react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";
import { useState } from "react";
import { Textarea } from "@/components/ui/textarea";
import { useAutoResizeTextarea } from "@/hooks/use-auto-resize-textarea";
import { cn } from "@/lib/utils";

const EASE_OUT = [0.23, 1, 0.32, 1] as const;

export interface AIInputSearchProps {
  placeholder?: string;
  searchLabel?: string;
  /** Receives the text and whether web search was on when it was sent. */
  onSubmit?: (value: string, options: { webSearch: boolean }) => void;
  /** Called with the files picked through the attach button. */
  onFilesSelected?: (files: File[]) => void;
  /** Controlled web-search state. Leave unset to let the component own it. */
  webSearch?: boolean;
  defaultWebSearch?: boolean;
  onWebSearchChange?: (webSearch: boolean) => void;
  className?: string;
}

export default function AI_Input_Search({
  placeholder = "Search the web...",
  searchLabel = "Search",
  onSubmit,
  onFilesSelected,
  webSearch: webSearchProp,
  defaultWebSearch = true,
  onWebSearchChange,
  className,
}: AIInputSearchProps) {
  const [value, setValue] = useState("");
  const { textareaRef, adjustHeight } = useAutoResizeTextarea({
    minHeight: 52,
    maxHeight: 200,
  });
  const [uncontrolledWebSearch, setUncontrolledWebSearch] =
    useState(defaultWebSearch);
  const webSearch = webSearchProp ?? uncontrolledWebSearch;
  const shouldReduceMotion = useReducedMotion();

  const toggleWebSearch = () => {
    const next = !webSearch;
    if (webSearchProp === undefined) {
      setUncontrolledWebSearch(next);
    }
    onWebSearchChange?.(next);
  };

  const handleSubmit = () => {
    if (!value.trim()) {
      return;
    }
    onSubmit?.(value, { webSearch });
    setValue("");
    adjustHeight(true);
  };

  // Mouse convenience: clicking the box around the field focuses it. Clicks
  // on the controls keep their own behaviour.
  const handleContainerClick = (target: EventTarget) => {
    if (target instanceof Element && target.closest("button, label, input")) {
      return;
    }
    textareaRef.current?.focus();
  };

  const canSubmit = value.trim().length > 0;

  return (
    <div className={cn("w-full py-4", className)}>
      <div className="relative mx-auto w-full max-w-xl">
        {/* biome-ignore lint/a11y/noStaticElementInteractions lint/a11y/useKeyWithClickEvents lint/a11y/noNoninteractiveElementInteractions: pointer-only shortcut; the textarea and buttons inside are keyboard reachable */}
        <div
          className={cn(
            "relative flex w-full cursor-text flex-col rounded-xl text-left transition-shadow duration-200",
            "ring-1 ring-black/10 dark:ring-white/10",
            "has-[textarea:focus-visible]:ring-2 has-[textarea:focus-visible]:ring-sky-600 dark:has-[textarea:focus-visible]:ring-sky-500"
          )}
          onClick={(e) => handleContainerClick(e.target)}
        >
          <Textarea
            aria-label={placeholder}
            className="min-h-[52px] w-full resize-none rounded-xl rounded-b-none border-none bg-black/5 px-4 py-3 leading-[1.2] placeholder:text-black/70 focus-visible:ring-0 dark:bg-white/5 dark:text-white dark:placeholder:text-white/70"
            onChange={(e) => {
              setValue(e.target.value);
              adjustHeight();
            }}
            onKeyDown={(e) => {
              if (
                e.key === "Enter" &&
                !e.shiftKey &&
                !e.nativeEvent.isComposing
              ) {
                e.preventDefault();
                handleSubmit();
              }
            }}
            placeholder={placeholder}
            ref={textareaRef}
            value={value}
          />

          <div className="flex items-center justify-between rounded-b-xl bg-black/5 px-3 pt-1 pb-3 dark:bg-white/5">
            <div className="flex items-center gap-2">
              <label className="group/attach cursor-pointer rounded-lg bg-black/5 p-2 transition-transform has-focus-visible:ring-2 has-focus-visible:ring-sky-600 motion-safe:active:scale-[0.97] dark:bg-white/5 dark:has-focus-visible:ring-sky-500">
                <input
                  aria-label="Attach file"
                  className="sr-only"
                  onChange={(e) => {
                    const files = Array.from(e.target.files ?? []);
                    // Clear so picking the same file again still fires onChange.
                    e.target.value = "";
                    if (files.length > 0) {
                      onFilesSelected?.(files);
                    }
                  }}
                  type="file"
                />
                <Paperclip className="h-4 w-4 text-black/40 transition-colors group-hover/attach:text-black dark:text-white/40 dark:group-hover/attach:text-white" />
              </label>
              <button
                aria-label={searchLabel}
                aria-pressed={webSearch}
                className={cn(
                  "flex h-8 cursor-pointer items-center gap-2 rounded-full border px-1.5 py-1 transition-[color,background-color,border-color,scale]",
                  webSearch
                    ? "border-sky-400 bg-sky-500/15 text-sky-500"
                    : "border-transparent bg-black/5 text-black/40 hover:text-black dark:bg-white/5 dark:text-white/40 dark:hover:text-white",
                  "motion-safe:active:scale-[0.97]"
                )}
                onClick={toggleWebSearch}
                type="button"
              >
                <div className="flex h-4 w-4 shrink-0 items-center justify-center">
                  <motion.div
                    transition={{ type: "spring", duration: 0.3, bounce: 0.15 }}
                    whileHover={
                      shouldReduceMotion
                        ? undefined
                        : { rotate: 15, scale: 1.1 }
                    }
                  >
                    <Globe
                      className={cn(
                        "h-4 w-4",
                        webSearch ? "text-sky-500" : "text-inherit"
                      )}
                    />
                  </motion.div>
                </div>
                <AnimatePresence initial={false}>
                  {webSearch && (
                    <motion.span
                      animate={{
                        width: "auto",
                        opacity: 1,
                      }}
                      className="shrink-0 overflow-hidden whitespace-nowrap text-sky-500 text-sm"
                      exit={{
                        width: 0,
                        opacity: 0,
                        transition: { duration: 0.15, ease: EASE_OUT },
                      }}
                      initial={{ width: 0, opacity: 0 }}
                      transition={{ duration: 0.2, ease: EASE_OUT }}
                    >
                      {searchLabel}
                    </motion.span>
                  )}
                </AnimatePresence>
              </button>
            </div>
            <button
              aria-label="Send"
              className={cn(
                "rounded-lg p-2 transition-[color,background-color,scale] motion-safe:active:scale-[0.97]",
                canSubmit
                  ? "cursor-pointer bg-sky-500/15 text-sky-500"
                  : "bg-black/5 text-black/40 dark:bg-white/5 dark:text-white/40"
              )}
              disabled={!canSubmit}
              onClick={handleSubmit}
              type="button"
            >
              <Send className="h-4 w-4" />
            </button>
          </div>
        </div>
      </div>
    </div>
  );
}
```


---

# AI State Loading
> Agent progress as a list of steps with a live log, elapsed time and a summary when done.

Source: https://kokonutui.com/docs/ai/ai-loading

## Installation

```bash
npx shadcn@latest add @kokonutui/ai-loading
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: AI Loading State
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { ChevronDown } from "lucide-react";
import { AnimatePresence, MotionConfig, motion } from "motion/react";
import { useEffect, useId, useRef, useState } from "react";
import { cn } from "@/lib/utils";

export type AgentStepStatus = "pending" | "running" | "done" | "error";

export interface AgentStep {
  id: string;
  label: string;
  status: AgentStepStatus;
  /** Log lines for the step. The running step shows the latest ones. */
  detail?: string[];
}

interface AILoadingStateProps {
  /**
   * The agent's steps, in order. Update them as work progresses. When
   * omitted, a demo run plays on a loop.
   */
  steps?: AgentStep[];
  /** Collapse the list once every step is done. Defaults to true. */
  collapseWhenDone?: boolean;
  className?: string;
}

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const LINE_HEIGHT = 24;
const VISIBLE_LINES = 3;

const DEMO_STEPS: Omit<AgentStep, "status">[] = [
  {
    id: "search",
    label: "Searching the web",
    detail: [
      "query: loading states in agent UIs",
      "visiting 5 websites",
      "reading emilkowal.ski/ui/great-animations",
      "reading developer.apple.com/design",
    ],
  },
  {
    id: "read",
    label: "Reading 4 sources",
    detail: [
      "extracting key passages",
      "dropping 1 duplicate source",
      "ranking by relevance",
    ],
  },
  {
    id: "compare",
    label: "Comparing approaches",
    detail: [
      "spinners vs. step lists",
      "progress you can verify",
      "checking motion preferences",
    ],
  },
  {
    id: "write",
    label: "Writing the summary",
    detail: ["drafting 3 sections"],
  },
];

const DEMO_TICK_MS = 750;
const DEMO_REST_MS = 3200;

interface DemoPosition {
  step: number;
  line: number;
}

const advanceDemo = ({ step, line }: DemoPosition): DemoPosition => {
  if (step >= DEMO_STEPS.length) {
    return { step: 0, line: 0 };
  }
  const lineCount = DEMO_STEPS[step].detail?.length ?? 0;
  return line < lineCount
    ? { step, line: line + 1 }
    : { step: step + 1, line: 0 };
};

/** Advances through DEMO_STEPS one log line per tick, pausing offscreen. */
function useDemoRun(
  enabled: boolean,
  rootRef: React.RefObject<HTMLElement | null>
) {
  const [position, setPosition] = useState<DemoPosition>({
    step: 0,
    line: 0,
  });
  const [isVisible, setIsVisible] = useState(true);

  useEffect(() => {
    const element = rootRef.current;
    if (!(enabled && element)) {
      return;
    }
    const observer = new IntersectionObserver(([entry]) =>
      setIsVisible(entry.isIntersecting)
    );
    observer.observe(element);
    return () => observer.disconnect();
  }, [enabled, rootRef]);

  const positionRef = useRef(position);

  useEffect(() => {
    if (!(enabled && isVisible)) {
      return;
    }
    let id: ReturnType<typeof setTimeout>;
    const schedule = () => {
      const finished = positionRef.current.step >= DEMO_STEPS.length;
      id = setTimeout(
        () => {
          positionRef.current = advanceDemo(positionRef.current);
          setPosition(positionRef.current);
          schedule();
        },
        finished ? DEMO_REST_MS : DEMO_TICK_MS
      );
    };
    schedule();
    return () => clearTimeout(id);
  }, [enabled, isVisible]);

  return DEMO_STEPS.map((step, i): AgentStep => {
    if (i < position.step) {
      return { ...step, status: "done" };
    }
    if (i === position.step) {
      return {
        ...step,
        status: "running",
        detail: step.detail?.slice(0, position.line),
      };
    }
    return { ...step, status: "pending" };
  });
}

function StepIcon({ status }: { status: AgentStepStatus }) {
  return (
    <span className="relative flex size-4 shrink-0 items-center justify-center">
      <AnimatePresence initial={false} mode="popLayout">
        <motion.span
          animate={{ opacity: 1, filter: "blur(0px)" }}
          className="absolute inset-0 flex items-center justify-center"
          exit={{ opacity: 0, filter: "blur(2px)" }}
          initial={{ opacity: 0, filter: "blur(2px)" }}
          key={status}
          transition={{ duration: 0.18, ease: EASE_OUT }}
        >
          {status === "pending" && (
            <span className="size-1.5 rounded-full bg-gray-300 dark:bg-gray-600" />
          )}
          {status === "running" && (
            <svg
              aria-hidden="true"
              className="size-3.5 motion-safe:animate-spin"
              fill="none"
              style={{ animationDuration: "0.8s" }}
              viewBox="0 0 16 16"
            >
              <circle
                className="stroke-gray-200 dark:stroke-gray-700"
                cx="8"
                cy="8"
                r="6.25"
                strokeWidth="1.5"
              />
              <path
                className="stroke-gray-700 dark:stroke-gray-200"
                d="M8 1.75a6.25 6.25 0 0 1 6.25 6.25"
                strokeLinecap="round"
                strokeWidth="1.5"
              />
            </svg>
          )}
          {status === "done" && (
            <svg
              aria-hidden="true"
              className="size-3.5 text-gray-700 dark:text-gray-200"
              fill="none"
              viewBox="0 0 16 16"
            >
              {/* The check draws itself once, from the short stroke out. */}
              <motion.path
                animate={{ pathLength: 1 }}
                d="M3.5 8.5 6.5 11.5 12.5 4.5"
                initial={{ pathLength: 0 }}
                stroke="currentColor"
                strokeLinecap="round"
                strokeLinejoin="round"
                strokeWidth="1.75"
                transition={{ duration: 0.3, ease: EASE_OUT, delay: 0.05 }}
              />
            </svg>
          )}
          {status === "error" && (
            <svg
              aria-hidden="true"
              className="size-3.5 text-red-500"
              fill="none"
              viewBox="0 0 16 16"
            >
              <path
                d="M4.5 4.5l7 7m0-7-7 7"
                stroke="currentColor"
                strokeLinecap="round"
                strokeWidth="1.75"
              />
            </svg>
          )}
        </motion.span>
      </AnimatePresence>
    </span>
  );
}

/** The running step's latest log lines, scrolling up as new ones arrive. */
function StepLog({ lines }: { lines: string[] }) {
  const offset = Math.max(0, lines.length - VISIBLE_LINES);
  return (
    <div
      aria-hidden="true"
      className="relative overflow-hidden font-mono text-xs"
      style={{
        height: LINE_HEIGHT * Math.min(lines.length, VISIBLE_LINES),
        maskImage:
          lines.length > VISIBLE_LINES - 1
            ? "linear-gradient(to bottom, rgb(0 0 0 / 0.25), black 70%)"
            : undefined,
        WebkitMaskImage:
          lines.length > VISIBLE_LINES - 1
            ? "linear-gradient(to bottom, rgb(0 0 0 / 0.25), black 70%)"
            : undefined,
        transition: "height 240ms cubic-bezier(0.23, 1, 0.32, 1)",
      }}
    >
      <div
        className="transition-transform duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none"
        style={{ transform: `translateY(${-offset * LINE_HEIGHT}px)` }}
      >
        {lines.map((line, index) => (
          <motion.div
            animate={{ opacity: 1 }}
            className="flex items-center gap-2 text-gray-500 dark:text-gray-400"
            initial={{ opacity: 0 }}
            key={`${index}-${line}`}
            style={{ height: LINE_HEIGHT }}
            transition={{ duration: 0.2, ease: EASE_OUT }}
          >
            <span className="w-4 select-none text-right text-gray-300 tabular-nums dark:text-gray-600">
              {index + 1}
            </span>
            <span className="truncate">{line}</span>
          </motion.div>
        ))}
      </div>
    </div>
  );
}

const formatDuration = (seconds: number) =>
  seconds < 60
    ? `${seconds}s`
    : `${Math.floor(seconds / 60)}m ${(seconds % 60).toString().padStart(2, "0")}s`;

/**
 * Seconds since the run started. Freezes while nothing runs, and restarts
 * when a step runs again after the whole list was done.
 */
function useElapsed(active: boolean, done: boolean) {
  const [seconds, setSeconds] = useState(0);
  const startRef = useRef<number | null>(null);
  const finishedRef = useRef(false);

  useEffect(() => {
    if (done) {
      finishedRef.current = true;
    }
  }, [done]);

  useEffect(() => {
    if (!active) {
      return;
    }
    if (finishedRef.current) {
      finishedRef.current = false;
      startRef.current = null;
    }
    const start = startRef.current ?? Date.now();
    startRef.current = start;
    const tick = () => setSeconds(Math.floor((Date.now() - start) / 1000));
    tick();
    const id = setInterval(tick, 500);
    return () => clearInterval(id);
  }, [active]);

  return seconds;
}

// Same stylesheet as AI Text Loading, so the two share one copy on a page.
const WAVE_CSS = `
@keyframes kokonut-ai-wave { 50% { opacity: 0.3; } }
.kokonut-ai-wave { animation: kokonut-ai-wave 1.6s ease-in-out infinite both; }
@media (prefers-reduced-motion: reduce) { .kokonut-ai-wave { animation: none; } }
`;

/** A soft brightness wave through the running step's letters. */
function WaveText({ text }: { text: string }) {
  return (
    <>
      <style href="kokonut-ai-wave" precedence="default">
        {WAVE_CSS}
      </style>
      {Array.from(text).map((char, i) => (
        <span
          className="kokonut-ai-wave whitespace-pre"
          // biome-ignore lint/suspicious/noArrayIndexKey: letters of one fixed label, never reordered
          key={i}
          style={{ animationDelay: `${i * 0.05}s` }}
        >
          {char}
        </span>
      ))}
    </>
  );
}

const formatStepTime = (ms: number) =>
  ms < 10_000 ? `${(ms / 1000).toFixed(1)}s` : `${Math.round(ms / 1000)}s`;

/**
 * Times each step from when it starts running to when it ends, so callers
 * only pass statuses. A step back to pending clears its time.
 */
function useStepTimes(steps: AgentStep[]) {
  const [times, setTimes] = useState<Record<string, number>>({});
  const startsRef = useRef<Record<string, number>>({});

  useEffect(() => {
    const now = Date.now();
    const starts = startsRef.current;
    const finished: Record<string, number> = {};
    let changed = false;
    for (const step of steps) {
      if (step.status === "pending") {
        delete starts[step.id];
        changed ||= step.id in times;
        continue;
      }
      // Running again after it had ended: a new run, so time it afresh.
      if (step.status === "running" && step.id in times) {
        starts[step.id] = now;
        changed = true;
      }
      starts[step.id] ??= now;
      if (step.status === "done" || step.status === "error") {
        finished[step.id] = times[step.id] ?? now - starts[step.id];
        changed ||= !(step.id in times);
      }
    }
    if (changed) {
      setTimes(finished);
    }
  }, [steps, times]);

  return times;
}

const LABEL_COLORS: Record<AgentStepStatus, string> = {
  pending: "text-gray-400 dark:text-gray-500",
  running: "text-gray-900 dark:text-gray-100",
  done: "text-gray-500 dark:text-gray-400",
  error: "text-red-600 dark:text-red-400",
};

function StepRow({
  step,
  time,
  isLast,
}: {
  step: AgentStep;
  time: number | undefined;
  isLast: boolean;
}) {
  return (
    <li className="relative flex gap-3 pt-3.5">
      {/* The rail between icons fills in as each step completes. */}
      {!isLast && (
        <span
          aria-hidden="true"
          className="absolute top-[34px] bottom-[-10px] left-[7.5px] w-px overflow-hidden bg-gray-200 dark:bg-gray-800"
        >
          <span
            className={cn(
              "block h-full w-full origin-top bg-gray-400 transition-transform duration-500 ease-[cubic-bezier(0.23,1,0.32,1)] dark:bg-gray-500",
              step.status === "done" ? "scale-y-100" : "scale-y-0"
            )}
          />
        </span>
      )}
      <StepIcon status={step.status} />
      <div className="-mt-0.5 min-w-0 flex-1">
        <div className="flex items-baseline gap-2">
          <p
            className={cn(
              "min-w-0 truncate text-sm transition-colors duration-200",
              LABEL_COLORS[step.status]
            )}
          >
            {step.status === "running" ? (
              <>
                <span className="sr-only">{step.label}</span>
                <span aria-hidden="true">
                  <WaveText text={step.label} />
                </span>
              </>
            ) : (
              step.label
            )}
          </p>
          {time !== undefined && (
            <motion.span
              animate={{ opacity: 1 }}
              className="ml-auto shrink-0 text-gray-400 text-xs tabular-nums dark:text-gray-500"
              initial={{ opacity: 0 }}
              transition={{ duration: 0.2, ease: EASE_OUT }}
            >
              {formatStepTime(time)}
            </motion.span>
          )}
        </div>
        {step.status === "running" && step.detail?.length ? (
          <div className="mt-1">
            <StepLog lines={step.detail} />
          </div>
        ) : null}
      </div>
    </li>
  );
}

export default function AILoadingState({
  steps: stepsProp,
  collapseWhenDone = true,
  className,
}: AILoadingStateProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const demoSteps = useDemoRun(stepsProp === undefined, rootRef);
  const steps = stepsProp ?? demoSteps;
  const listId = useId();

  const running = steps.find((step) => step.status === "running");
  const failed = steps.find((step) => step.status === "error");
  const isDone =
    steps.length > 0 && steps.every((step) => step.status === "done");
  const isActive = Boolean(running);
  const seconds = useElapsed(isActive, isDone);
  const times = useStepTimes(steps);

  // Open while working; folds away once everything is done, until the user
  // opens it again.
  const [isOpen, setIsOpen] = useState(true);
  useEffect(() => {
    setIsOpen(!(isDone && collapseWhenDone));
  }, [isDone, collapseWhenDone]);

  let title = "Getting ready";
  if (failed) {
    title = `Stopped at: ${failed.label}`;
  } else if (isDone) {
    title = `Worked for ${formatDuration(seconds)}`;
  } else if (running) {
    title = running.label;
  }

  return (
    <div
      className={cn("flex w-full items-center justify-center", className)}
      ref={rootRef}
    >
      <MotionConfig reducedMotion="user">
        <div className="w-full max-w-sm">
          <button
            aria-controls={listId}
            aria-expanded={isOpen}
            className="group/header flex w-full items-center gap-2 rounded-md py-1 text-left font-medium text-gray-600 text-sm outline-hidden focus-visible:ring-2 focus-visible:ring-gray-400/40 dark:text-gray-300"
            onClick={() => setIsOpen((open) => !open)}
            type="button"
          >
            {/* <output> has the implicit role="status", so the current step
                is announced as it changes. */}
            <output className="min-w-0 truncate">{title}</output>
            {isActive && (
              <span className="text-gray-400 tabular-nums dark:text-gray-500">
                {formatDuration(seconds)}
              </span>
            )}
            {isDone && (
              <span className="text-gray-400 dark:text-gray-500">
                · {steps.length} steps
              </span>
            )}
            <ChevronDown
              aria-hidden="true"
              className={cn(
                "ml-auto size-4 text-gray-400 transition-transform duration-200 ease-[cubic-bezier(0.23,1,0.32,1)] group-hover/header:text-gray-600 dark:group-hover/header:text-gray-300",
                isOpen && "rotate-180"
              )}
            />
          </button>

          <AnimatePresence initial={false}>
            {isOpen && (
              <motion.ol
                animate={{ height: "auto", opacity: 1 }}
                className="overflow-hidden"
                exit={{ height: 0, opacity: 0 }}
                id={listId}
                initial={{ height: 0, opacity: 0 }}
                transition={{ duration: 0.25, ease: EASE_OUT }}
              >
                {steps.map((step, i) => (
                  <StepRow
                    isLast={i === steps.length - 1}
                    key={step.id}
                    step={step}
                    time={times[step.id]}
                  />
                ))}
              </motion.ol>
            )}
          </AnimatePresence>
        </div>
      </MotionConfig>
    </div>
  );
}
```


---

# AI Input Selector
> AI chat input with a model picker, file chips you can drop or paste, and Stop while replying.

Source: https://kokonutui.com/docs/ai/ai-prompt

## Installation

```bash
npx shadcn@latest add @kokonutui/ai-prompt
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: AI Prompt Input
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  AlignLeft,
  ArrowRight,
  Bot,
  Check,
  ChevronDown,
  Code2,
  FileText,
  Languages,
  Lightbulb,
  Paperclip,
  Slash,
  X,
} from "lucide-react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";
import { type ReactNode, useEffect, useId, useRef, useState } from "react";
import Anthropic from "@/components/icons/anthropic";
import AnthropicDark from "@/components/icons/anthropic-dark";
import { Button } from "@/components/ui/button";
import {
  DropdownMenu,
  DropdownMenuContent,
  DropdownMenuItem,
  DropdownMenuTrigger,
} from "@/components/ui/dropdown-menu";
import { Textarea } from "@/components/ui/textarea";
import { useAutoResizeTextarea } from "@/hooks/use-auto-resize-textarea";
import { cn } from "@/lib/utils";

// Decorative: each icon sits next to the model name, which carries the label.
const OPENAI_ICON = (
  <svg
    aria-hidden="true"
    fill="currentColor"
    height="1em"
    preserveAspectRatio="xMidYMid"
    viewBox="0 0 256 260"
    width="1em"
    xmlns="http://www.w3.org/2000/svg"
  >
    <path d="M239.184 106.203a64.716 64.716 0 0 0-5.576-53.103C219.452 28.459 191 15.784 163.213 21.74A65.586 65.586 0 0 0 52.096 45.22a64.716 64.716 0 0 0-43.23 31.36c-14.31 24.602-11.061 55.634 8.033 76.74a64.665 64.665 0 0 0 5.525 53.102c14.174 24.65 42.644 37.324 70.446 31.36a64.72 64.72 0 0 0 48.754 21.744c28.481.025 53.714-18.361 62.414-45.481a64.767 64.767 0 0 0 43.229-31.36c14.137-24.558 10.875-55.423-8.083-76.483Zm-97.56 136.338a48.397 48.397 0 0 1-31.105-11.255l1.535-.87 51.67-29.825a8.595 8.595 0 0 0 4.247-7.367v-72.85l21.845 12.636c.218.111.37.32.409.563v60.367c-.056 26.818-21.783 48.545-48.601 48.601Zm-104.466-44.61a48.345 48.345 0 0 1-5.781-32.589l1.534.921 51.722 29.826a8.339 8.339 0 0 0 8.441 0l63.181-36.425v25.221a.87.87 0 0 1-.358.665l-52.335 30.184c-23.257 13.398-52.97 5.431-66.404-17.803ZM23.549 85.38a48.499 48.499 0 0 1 25.58-21.333v61.39a8.288 8.288 0 0 0 4.195 7.316l62.874 36.272-21.845 12.636a.819.819 0 0 1-.767 0L41.353 151.53c-23.211-13.454-31.171-43.144-17.804-66.405v.256Zm179.466 41.695-63.08-36.63L161.73 77.86a.819.819 0 0 1 .768 0l52.233 30.184a48.6 48.6 0 0 1-7.316 87.635v-61.391a8.544 8.544 0 0 0-4.4-7.213Zm21.742-32.69-1.535-.922-51.619-30.081a8.39 8.39 0 0 0-8.492 0L99.98 99.808V74.587a.716.716 0 0 1 .307-.665l52.233-30.133a48.652 48.652 0 0 1 72.236 50.391v.205ZM88.061 139.097l-21.845-12.585a.87.87 0 0 1-.41-.614V65.685a48.652 48.652 0 0 1 79.757-37.346l-1.535.87-51.67 29.825a8.595 8.595 0 0 0-4.246 7.367l-.051 72.697Zm11.868-25.58 28.138-16.217 28.188 16.218v32.434l-28.086 16.218-28.188-16.218-.052-32.434Z" />
  </svg>
);

// Rendered once in the trigger and once in the menu, so every instance needs
// its own gradient id.
function GeminiIcon() {
  const gradientId = useId();

  return (
    <svg
      aria-hidden="true"
      height="1em"
      style={{ flex: "none", lineHeight: "1" }}
      viewBox="0 0 24 24"
      xmlns="http://www.w3.org/2000/svg"
    >
      <defs>
        <linearGradient
          id={gradientId}
          x1="0%"
          x2="68.73%"
          y1="100%"
          y2="30.395%"
        >
          <stop offset="0%" stopColor="#1C7DFF" />
          <stop offset="52.021%" stopColor="#1C69FF" />
          <stop offset="100%" stopColor="#F0DCD6" />
        </linearGradient>
      </defs>
      <path
        d="M12 24A14.304 14.304 0 000 12 14.304 14.304 0 0012 0a14.305 14.305 0 0012 12 14.305 14.305 0 00-12 12"
        fill={`url(#${gradientId})`}
        fillRule="nonzero"
      />
    </svg>
  );
}

export interface PromptCommand {
  id: string;
  label: string;
  description?: string;
  icon?: ReactNode;
}

export interface PromptAttachment {
  id: string;
  file: File;
}

interface AIPromptProps {
  models?: string[];
  defaultModel?: string;
  placeholder?: string;
  headerText?: string;
  headerAction?: string;
  /**
   * Sends the message. Return a promise to show the Stop button until it
   * settles; `signal` aborts when the user presses Stop. Without it, the
   * component plays a short pretend reply so the demo feels alive.
   */
  onSubmit?: (
    value: string,
    model: string,
    options: {
      files: File[];
      signal: AbortSignal;
      command: PromptCommand | null;
    }
  ) => unknown;
  /** Shown when the message starts with "/". Pass [] to turn the menu off. */
  commands?: PromptCommand[];
  /** Called when the user presses Stop while a reply is in progress. */
  onStop?: () => void;
  /** Called with the files picked, dropped or pasted into the prompt. */
  onAttach?: (files: FileList | File[]) => void;
  className?: string;
}

const DEFAULT_COMMANDS: PromptCommand[] = [
  {
    id: "summarize",
    label: "Summarize",
    description: "Shorten text or files",
    icon: <AlignLeft className="size-4" />,
  },
  {
    id: "translate",
    label: "Translate",
    description: "Into another language",
    icon: <Languages className="size-4" />,
  },
  {
    id: "explain",
    label: "Explain",
    description: "Step by step, in plain words",
    icon: <Lightbulb className="size-4" />,
  },
  {
    id: "code",
    label: "Write code",
    description: "Functions, tests and fixes",
    icon: <Code2 className="size-4" />,
  },
];

const DEFAULT_MODELS = [
  "Gemini 3 Pro",
  "GPT-5.6 Mini",
  "Claude Fable 5",
  "GPT-5.6 Codex",
  "GPT-5.6",
];

const ANTHROPIC_ICON = (
  <svg
    aria-hidden="true"
    fill="currentColor"
    fillRule="evenodd"
    height="1em"
    style={{ flex: "none", lineHeight: "1" }}
    viewBox="0 0 24 24"
    width="1em"
    xmlns="http://www.w3.org/2000/svg"
  >
    <path d="M13.827 3.52h3.603L24 20h-3.603l-6.57-16.48zm-7.258 0h3.767L16.906 20h-3.674l-1.343-3.461H5.017l-1.344 3.46H0L6.57 3.522zm4.132 9.959L8.453 7.687 6.205 13.48H10.7z" />
  </svg>
);

const MODEL_ICONS: Record<string, ReactNode> = {
  "GPT-5.6 Mini": OPENAI_ICON,
  "Gemini 3 Pro": <GeminiIcon />,
  "Claude Fable 5": ANTHROPIC_ICON,
  "GPT-5.6 Codex": OPENAI_ICON,
  "GPT-5.6": OPENAI_ICON,
};

const getModelIcon = (model: string) =>
  MODEL_ICONS[model] ?? (
    <Bot aria-hidden="true" className="h-4 w-4 opacity-50" />
  );

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const DEMO_REPLY_MS = 2400;
const WHITESPACE = /\s/;

const formatSize = (bytes: number) => {
  if (bytes < 1024) {
    return `${bytes} B`;
  }
  if (bytes < 1024 * 1024) {
    return `${Math.round(bytes / 1024)} KB`;
  }
  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
};

const waitFor = (ms: number, signal: AbortSignal) =>
  new Promise<void>((resolve) => {
    const id = setTimeout(resolve, ms);
    signal.addEventListener("abort", () => {
      clearTimeout(id);
      resolve();
    });
  });

function AttachmentChip({
  attachment,
  onRemove,
}: {
  attachment: PromptAttachment;
  onRemove: () => void;
}) {
  const { file } = attachment;
  const isImage = file.type.startsWith("image/");
  const [previewUrl, setPreviewUrl] = useState<string | null>(null);

  // Object URLs are created after mount and revoked on unmount, so a
  // removed chip doesn't keep its image in memory.
  useEffect(() => {
    if (!isImage) {
      return;
    }
    const url = URL.createObjectURL(file);
    setPreviewUrl(url);
    return () => URL.revokeObjectURL(url);
  }, [file, isImage]);

  return (
    <motion.li
      animate={{ opacity: 1, y: 0, filter: "blur(0px)" }}
      className="flex h-11 max-w-52 items-center gap-2 rounded-lg bg-white py-1 pr-1.5 pl-1 ring-1 ring-black/5 dark:bg-white/10 dark:ring-white/10"
      exit={{
        opacity: 0,
        filter: "blur(2px)",
        transition: { duration: 0.12, ease: EASE_OUT },
      }}
      initial={{ opacity: 0, y: 4, filter: "blur(2px)" }}
      layout="position"
      transition={{ duration: 0.2, ease: EASE_OUT }}
    >
      <span className="flex size-9 shrink-0 items-center justify-center overflow-hidden rounded-md bg-black/5 text-black/50 dark:bg-white/10 dark:text-white/60">
        {previewUrl ? (
          // biome-ignore lint/performance/noImgElement: object URL preview, nothing to optimise
          <img
            alt=""
            className="size-full object-cover"
            height={36}
            src={previewUrl}
            width={36}
          />
        ) : (
          <FileText aria-hidden="true" className="size-4" />
        )}
      </span>
      <span className="min-w-0 flex-1 leading-tight">
        <span className="block truncate text-black text-xs dark:text-white">
          {file.name}
        </span>
        <span className="block text-[10px] text-black/50 tabular-nums dark:text-white/50">
          {formatSize(file.size)}
        </span>
      </span>
      <button
        aria-label={`Remove ${file.name}`}
        className="flex size-6 shrink-0 items-center justify-center rounded-md text-black/40 transition-colors duration-150 hover:bg-black/5 hover:text-black focus-visible:outline-hidden focus-visible:ring-1 focus-visible:ring-blue-500 dark:text-white/40 dark:hover:bg-white/10 dark:hover:text-white"
        onClick={onRemove}
        type="button"
      >
        <X aria-hidden="true" className="size-3.5" />
      </button>
    </motion.li>
  );
}

function CommandMenu({
  id,
  commands,
  activeIndex,
  onHover,
  onSelect,
}: {
  id: string;
  commands: PromptCommand[];
  activeIndex: number;
  onHover: (index: number) => void;
  onSelect: (command: PromptCommand) => void;
}) {
  return (
    <motion.div
      animate={{ opacity: 1, y: 0, scale: 1 }}
      className="absolute inset-x-0 bottom-full z-10 mb-2 origin-bottom rounded-xl bg-white p-1 shadow-[0_8px_24px_-8px_rgb(0_0_0/0.18)] ring-1 ring-black/10 dark:bg-zinc-900 dark:ring-white/10"
      exit={{ opacity: 0, y: 2, scale: 0.98, transition: { duration: 0.1 } }}
      initial={{ opacity: 0, y: 4, scale: 0.98 }}
      transition={{ duration: 0.15, ease: EASE_OUT }}
    >
      {/* The highlight follows the keyboard instantly, without a transition. */}
      <div aria-label="Commands" id={id} role="listbox">
        {commands.map((command, i) => (
          // biome-ignore lint/a11y/useKeyWithClickEvents: options are driven from the textarea with the arrow keys
          <div
            aria-selected={i === activeIndex}
            className={cn(
              "flex h-9 cursor-pointer items-center gap-2 rounded-lg px-2",
              i === activeIndex && "bg-black/5 dark:bg-white/10"
            )}
            id={`${id}-${command.id}`}
            key={command.id}
            onClick={() => onSelect(command)}
            onMouseDown={(e) => e.preventDefault()}
            onPointerMove={() => onHover(i)}
            role="option"
            tabIndex={-1}
          >
            <span className="flex size-6 shrink-0 items-center justify-center text-black/50 dark:text-white/60 [&_svg]:size-4">
              {command.icon ?? <Slash />}
            </span>
            <span className="text-black text-sm dark:text-white">
              {command.label}
            </span>
            {command.description && (
              <span className="min-w-0 truncate text-black/40 text-xs dark:text-white/40">
                {command.description}
              </span>
            )}
          </div>
        ))}
      </div>
    </motion.div>
  );
}

function CommandPill({
  command,
  onRemove,
}: {
  command: PromptCommand;
  onRemove: () => void;
}) {
  return (
    <motion.li
      animate={{ opacity: 1, y: 0, filter: "blur(0px)" }}
      className="flex h-11 items-center gap-1.5 rounded-lg bg-blue-500/10 pr-1.5 pl-2.5 text-blue-600 text-sm dark:text-blue-400"
      exit={{
        opacity: 0,
        filter: "blur(2px)",
        transition: { duration: 0.12, ease: EASE_OUT },
      }}
      initial={{ opacity: 0, y: 4, filter: "blur(2px)" }}
      layout="position"
      transition={{ duration: 0.2, ease: EASE_OUT }}
    >
      <span aria-hidden="true" className="opacity-60">
        /
      </span>
      {command.label}
      <button
        aria-label={`Remove ${command.label} command`}
        className="flex size-6 items-center justify-center rounded-md transition-colors duration-150 hover:bg-blue-500/10 focus-visible:outline-hidden focus-visible:ring-1 focus-visible:ring-blue-500"
        onClick={onRemove}
        type="button"
      >
        <X aria-hidden="true" className="size-3.5" />
      </button>
    </motion.li>
  );
}

function SendButton({
  responding,
  canSend,
  onSend,
  onStop,
}: {
  responding: boolean;
  canSend: boolean;
  onSend: () => void;
  onStop: () => void;
}) {
  // One button with two faces. The faces crossfade with a little blur, so
  // Send turning into Stop reads as the same control changing state.
  const face =
    "absolute inset-0 flex items-center justify-center transition-[opacity,filter] duration-200 ease-[cubic-bezier(0.23,1,0.32,1)]";
  return (
    <button
      aria-label={responding ? "Stop response" : "Send message"}
      className={cn(
        "relative size-8 rounded-lg",
        "focus-visible:outline-hidden focus-visible:ring-1 focus-visible:ring-blue-500",
        "transition-[background-color] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)]",
        responding
          ? "bg-black text-white hover:bg-black/80 dark:bg-white dark:text-black dark:hover:bg-white/80"
          : "bg-black/5 hover:bg-black/10 disabled:pointer-events-none dark:bg-white/5 dark:hover:bg-white/10"
      )}
      disabled={!(responding || canSend)}
      onClick={responding ? onStop : onSend}
      type="button"
    >
      <span
        aria-hidden="true"
        className={cn(
          face,
          responding ? "opacity-0 blur-[2px]" : "opacity-100 blur-0"
        )}
      >
        <ArrowRight
          className={cn(
            "h-4 w-4 transition-opacity duration-200 dark:text-white",
            canSend ? "opacity-100" : "opacity-30"
          )}
        />
      </span>
      <span
        aria-hidden="true"
        className={cn(
          face,
          responding ? "opacity-100 blur-0" : "opacity-0 blur-[2px]"
        )}
      >
        <span className="size-2.5 rounded-[2px] bg-current" />
      </span>
    </button>
  );
}

export default function AI_Prompt({
  models = DEFAULT_MODELS,
  defaultModel = "Claude Fable 5",
  placeholder = "What can I do for you? Type / for commands",
  headerText = "is free this weekend!",
  headerAction = "Ship Now!",
  onSubmit,
  onStop,
  onAttach,
  commands = DEFAULT_COMMANDS,
  className,
}: AIPromptProps) {
  const [value, setValue] = useState("");
  const [command, setCommand] = useState<PromptCommand | null>(null);
  const [menuIndex, setMenuIndex] = useState(0);
  const [menuDismissed, setMenuDismissed] = useState(false);
  const menuId = useId();
  const [attachments, setAttachments] = useState<PromptAttachment[]>([]);
  const [responding, setResponding] = useState(false);
  const [isDragging, setIsDragging] = useState(false);
  const abortRef = useRef<AbortController | null>(null);
  const nextIdRef = useRef(0);
  const { textareaRef, adjustHeight } = useAutoResizeTextarea({
    minHeight: 72,
    maxHeight: 300,
  });
  // A default that is not in `models` would show a model the menu can't pick.
  const [selectedModel, setSelectedModel] = useState(() =>
    models.includes(defaultModel) ? defaultModel : (models[0] ?? defaultModel)
  );
  const textareaId = useId();
  const shouldReduceMotion = useReducedMotion();
  const labelOffset = shouldReduceMotion ? 0 : 5;

  useEffect(() => () => abortRef.current?.abort(), []);

  const addFiles = (files: FileList | File[]) => {
    const list = Array.from(files);
    if (list.length === 0) {
      return;
    }
    onAttach?.(files);
    setAttachments((current) => [
      ...current,
      ...list.map((file) => {
        nextIdRef.current += 1;
        return { id: `attachment-${nextIdRef.current}`, file };
      }),
    ]);
  };

  const removeAttachment = (id: string) => {
    setAttachments((current) => current.filter((a) => a.id !== id));
    textareaRef.current?.focus();
  };

  // "/" at the very start opens the menu; the text after it filters it.
  const slashQuery =
    !command && value.startsWith("/") && !WHITESPACE.test(value)
      ? value.slice(1).toLowerCase()
      : null;
  const matches =
    slashQuery === null
      ? []
      : commands.filter((c) => c.label.toLowerCase().includes(slashQuery));
  const menuOpen = matches.length > 0 && !menuDismissed;
  const activeIndex = Math.min(menuIndex, matches.length - 1);

  const pickCommand = (picked: PromptCommand) => {
    setCommand(picked);
    setValue("");
    setMenuIndex(0);
    adjustHeight(true);
    textareaRef.current?.focus();
  };

  const canSend = value.trim().length > 0 && !responding;

  const submit = async () => {
    if (!canSend) {
      return;
    }
    const controller = new AbortController();
    abortRef.current = controller;
    const files = attachments.map((a) => a.file);
    const sentCommand = command;
    setValue("");
    setAttachments([]);
    setCommand(null);
    adjustHeight(true);
    setResponding(true);
    try {
      await (onSubmit
        ? onSubmit(value, selectedModel, {
            files,
            signal: controller.signal,
            command: sentCommand,
          })
        : waitFor(DEMO_REPLY_MS, controller.signal));
    } finally {
      if (abortRef.current === controller) {
        abortRef.current = null;
        setResponding(false);
      }
    }
  };

  const stop = () => {
    abortRef.current?.abort();
    abortRef.current = null;
    setResponding(false);
    onStop?.();
    textareaRef.current?.focus();
  };

  const handleMenuKey = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
    const step = { ArrowDown: 1, ArrowUp: -1 }[e.key];
    if (step) {
      e.preventDefault();
      setMenuIndex((activeIndex + step + matches.length) % matches.length);
      return true;
    }
    if (e.key === "Enter" || e.key === "Tab") {
      e.preventDefault();
      pickCommand(matches[activeIndex]);
      return true;
    }
    if (e.key === "Escape") {
      e.preventDefault();
      setMenuDismissed(true);
      return true;
    }
    return false;
  };

  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
    if (e.nativeEvent.isComposing) {
      return;
    }
    if (menuOpen && handleMenuKey(e)) {
      return;
    }
    // Backspace in an empty prompt takes the command off first.
    if (e.key === "Backspace" && command && value === "") {
      e.preventDefault();
      setCommand(null);
      return;
    }
    // Enter during IME composition confirms the candidate; it must not submit.
    if (e.key === "Enter" && !e.shiftKey) {
      e.preventDefault();
      submit();
    } else if (e.key === "Escape" && responding) {
      e.preventDefault();
      stop();
    }
  };

  const hasFiles = (e: React.DragEvent) =>
    Array.from(e.dataTransfer.types).includes("Files");

  return (
    <div className={cn("w-full max-w-md py-4", className)}>
      <div className="rounded-2xl bg-black/5 p-1.5 pt-4 dark:bg-white/5">
        <div className="mx-2 mb-2.5 flex items-center gap-2">
          <div className="flex flex-1 items-center gap-2">
            <Anthropic className="h-3.5 w-3.5 text-black dark:hidden" />
            <AnthropicDark className="hidden h-3.5 w-3.5 dark:block" />
            <p className="text-black text-xs tracking-tighter dark:text-white/90">
              {headerText}
            </p>
          </div>
          <p className="text-black text-xs tracking-tighter dark:text-white/90">
            {headerAction}
          </p>
        </div>
        {/* biome-ignore lint/a11y/noStaticElementInteractions lint/a11y/noNoninteractiveElementInteractions: drop target for files; keyboard users have the attach button */}
        <div
          className={cn(
            "relative flex flex-col rounded-xl has-[textarea:focus-visible]:ring-1 has-[textarea:focus-visible]:ring-blue-500",
            isDragging && "ring-1 ring-blue-500"
          )}
          onDragLeave={(e) => {
            if (!e.currentTarget.contains(e.relatedTarget as Node | null)) {
              setIsDragging(false);
            }
          }}
          onDragOver={(e) => {
            if (hasFiles(e)) {
              e.preventDefault();
              setIsDragging(true);
            }
          }}
          onDrop={(e) => {
            if (!hasFiles(e)) {
              return;
            }
            e.preventDefault();
            setIsDragging(false);
            addFiles(e.dataTransfer.files);
          }}
        >
          <AnimatePresence initial={false}>
            {(attachments.length > 0 || command) && (
              <motion.div
                animate={{ height: "auto", opacity: 1 }}
                className="overflow-hidden rounded-t-xl bg-black/5 dark:bg-white/5"
                exit={{ height: 0, opacity: 0 }}
                initial={{ height: 0, opacity: 0 }}
                transition={{
                  duration: shouldReduceMotion ? 0 : 0.2,
                  ease: EASE_OUT,
                }}
              >
                <ul
                  aria-label="Attachments"
                  className="flex flex-wrap gap-2 px-3 pt-3"
                >
                  <AnimatePresence initial={false} mode="popLayout">
                    {command && (
                      <CommandPill
                        command={command}
                        key={`command-${command.id}`}
                        onRemove={() => {
                          setCommand(null);
                          textareaRef.current?.focus();
                        }}
                      />
                    )}
                    {attachments.map((attachment) => (
                      <AttachmentChip
                        attachment={attachment}
                        key={attachment.id}
                        onRemove={() => removeAttachment(attachment.id)}
                      />
                    ))}
                  </AnimatePresence>
                </ul>
              </motion.div>
            )}
          </AnimatePresence>
          <label className="sr-only" htmlFor={textareaId}>
            Message
          </label>
          <AnimatePresence>
            {menuOpen && (
              <CommandMenu
                activeIndex={activeIndex}
                commands={matches}
                id={menuId}
                onHover={setMenuIndex}
                onSelect={pickCommand}
              />
            )}
          </AnimatePresence>
          <Textarea
            aria-activedescendant={
              menuOpen ? `${menuId}-${matches[activeIndex].id}` : undefined
            }
            aria-autocomplete="list"
            aria-controls={menuOpen ? menuId : undefined}
            aria-expanded={menuOpen}
            className={cn(
              "w-full resize-none rounded-xl rounded-b-none border-none bg-black/5 px-4 py-3 placeholder:text-black/70 focus-visible:ring-0 focus-visible:ring-offset-0 dark:bg-white/5 dark:text-white dark:placeholder:text-white/70",
              "min-h-[72px]",
              (attachments.length > 0 || command) && "rounded-t-none"
            )}
            id={textareaId}
            onBlur={() => setMenuDismissed(true)}
            onChange={(e) => {
              setValue(e.target.value);
              setMenuDismissed(false);
              setMenuIndex(0);
              adjustHeight();
            }}
            onFocus={() => setMenuDismissed(false)}
            onKeyDown={handleKeyDown}
            onPaste={(e) => {
              if (e.clipboardData.files.length > 0) {
                e.preventDefault();
                addFiles(e.clipboardData.files);
              }
            }}
            placeholder={placeholder}
            ref={textareaRef}
            value={value}
          />

          <div className="flex h-14 items-center justify-between rounded-b-xl bg-black/5 px-3 dark:bg-white/5">
            <div className="flex items-center gap-2">
              <DropdownMenu>
                <DropdownMenuTrigger asChild>
                  <Button
                    className="relative flex h-8 items-center gap-1 rounded-md pr-2 pl-1 text-xs hover:bg-black/10 focus-visible:ring-1 focus-visible:ring-blue-500 focus-visible:ring-offset-0 dark:text-white dark:hover:bg-white/10"
                    variant="ghost"
                  >
                    <AnimatePresence initial={false} mode="popLayout">
                      <motion.div
                        animate={{
                          opacity: 1,
                          y: 0,
                        }}
                        className="flex items-center gap-1"
                        exit={{
                          opacity: 0,
                          y: labelOffset,
                        }}
                        initial={{
                          opacity: 0,
                          y: -labelOffset,
                        }}
                        key={selectedModel}
                        transition={{
                          duration: 0.15,
                          ease: EASE_OUT,
                        }}
                      >
                        {getModelIcon(selectedModel)}
                        {selectedModel}
                        <ChevronDown className="h-3 w-3 opacity-50" />
                      </motion.div>
                    </AnimatePresence>
                  </Button>
                </DropdownMenuTrigger>
                <DropdownMenuContent className="min-w-[10rem] border-black/10 dark:border-white/10">
                  {models.map((model) => (
                    <DropdownMenuItem
                      className="flex items-center justify-between gap-2"
                      key={model}
                      onSelect={() => setSelectedModel(model)}
                    >
                      <div className="flex items-center gap-2">
                        {getModelIcon(model)}
                        <span>{model}</span>
                      </div>
                      {selectedModel === model && (
                        <Check className="h-4 w-4 text-blue-500" />
                      )}
                    </DropdownMenuItem>
                  ))}
                </DropdownMenuContent>
              </DropdownMenu>
              <div className="mx-0.5 h-4 w-px bg-black/10 dark:bg-white/10" />
              <label
                className={cn(
                  "cursor-pointer rounded-lg bg-black/5 p-2 dark:bg-white/5",
                  "hover:bg-black/10 has-focus-visible:ring-1 has-focus-visible:ring-blue-500 has-focus-visible:ring-offset-0 dark:hover:bg-white/10",
                  "text-black/40 hover:text-black dark:text-white/40 dark:hover:text-white",
                  "transition-[background-color,color] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)]"
                )}
              >
                <input
                  aria-label="Attach files"
                  className="sr-only"
                  multiple
                  onChange={(e) => {
                    if (e.target.files?.length) {
                      addFiles(e.target.files);
                    }
                    // Cleared so picking the same file again still fires.
                    e.target.value = "";
                  }}
                  type="file"
                />
                <Paperclip className="h-4 w-4 transition-colors" />
              </label>
            </div>
            <SendButton
              canSend={canSend}
              onSend={submit}
              onStop={stop}
              responding={responding}
            />
          </div>

          {/* Shown while files are dragged over the prompt. */}
          <div
            aria-hidden="true"
            className={cn(
              "pointer-events-none absolute inset-0 flex items-center justify-center rounded-xl border border-blue-500/50 border-dashed bg-white/80 text-blue-600 text-xs transition-opacity duration-150 dark:bg-black/70 dark:text-blue-400",
              isDragging ? "opacity-100" : "opacity-0"
            )}
          >
            Drop files to attach
          </div>
        </div>
      </div>
    </div>
  );
}
```


---

# AI Text Loading
> AI thinking text with a soft wave through the letters and words that swap letter by letter.

Source: https://kokonutui.com/docs/ai/ai-text-loading

## Installation

```bash
npx shadcn@latest add @kokonutui/ai-text-loading
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: AI Text Loading
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  AnimatePresence,
  MotionConfig,
  motion,
  type Variants,
} from "motion/react";
import { useEffect, useState } from "react";
import { cn } from "@/lib/utils";

interface AITextLoadingProps {
  texts?: string[];
  className?: string;
  interval?: number;
  /** Stable status for screen readers; the cycling words are hidden from them. */
  label?: string;
  /** Show the seconds spent so far next to the words. */
  showElapsed?: boolean;
}

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
// Gap between neighbouring letters in the wave, and one wave's length.
const WAVE_STEP = 0.07;
const WAVE_CSS = `
@keyframes kokonut-ai-wave { 50% { opacity: 0.3; } }
.kokonut-ai-wave { animation: kokonut-ai-wave 1.6s ease-in-out infinite both; }
@media (prefers-reduced-motion: reduce) { .kokonut-ai-wave { animation: none; } }
`;

const wordVariants = {
  enter: {},
  shown: { transition: { staggerChildren: 0.018 } },
  exit: {
    opacity: 0,
    y: -6,
    filter: "blur(3px)",
    transition: { duration: 0.15, ease: EASE_OUT },
  },
} satisfies Variants;

const letterVariants = {
  enter: { opacity: 0, y: 8, filter: "blur(4px)" },
  shown: {
    opacity: 1,
    y: 0,
    filter: "blur(0px)",
    transition: { duration: 0.28, ease: EASE_OUT },
  },
} satisfies Variants;

export default function AITextLoading({
  texts = [
    "Thinking...",
    "Processing...",
    "Analyzing...",
    "Computing...",
    "Almost...",
  ],
  className,
  interval = 1500,
  label = "Loading",
  showElapsed = false,
}: AITextLoadingProps) {
  const [currentTextIndex, setCurrentTextIndex] = useState(0);
  const [seconds, setSeconds] = useState(0);
  // Clamped, so a shorter (or empty) `texts` never reads past the end.
  const textIndex = texts.length > 0 ? currentTextIndex % texts.length : 0;
  const text = texts[textIndex] ?? "";

  useEffect(() => {
    if (texts.length < 2) {
      return;
    }
    const timer = setInterval(() => {
      setCurrentTextIndex((prevIndex) => (prevIndex + 1) % texts.length);
    }, interval);

    return () => clearInterval(timer);
  }, [interval, texts.length]);

  useEffect(() => {
    if (!showElapsed) {
      return;
    }
    const startedAt = Date.now();
    const timer = setInterval(
      () => setSeconds(Math.floor((Date.now() - startedAt) / 1000)),
      500
    );
    return () => clearInterval(timer);
  }, [showElapsed]);

  return (
    <output
      aria-live="polite"
      className={cn(
        "flex items-baseline justify-center gap-3 font-bold text-3xl text-neutral-950 dark:text-white",
        className
      )}
    >
      {/* React hoists and dedupes this, so several loaders share one copy. */}
      <style href="kokonut-ai-wave" precedence="default">
        {WAVE_CSS}
      </style>
      <span className="sr-only">{label}</span>
      {/* With reduced motion the words swap with a fade only, and the
          letters hold still instead of waving. */}
      <MotionConfig reducedMotion="user">
        <span aria-hidden="true" className="relative flex justify-center">
          <AnimatePresence initial={false} mode="popLayout">
            <motion.span
              animate="shown"
              className="flex min-w-max justify-center whitespace-pre"
              exit="exit"
              initial="enter"
              key={textIndex}
              variants={wordVariants}
            >
              {Array.from(text).map((char, i) => (
                <motion.span
                  className="inline-block"
                  // biome-ignore lint/suspicious/noArrayIndexKey: letters of one fixed word, never reordered
                  key={i}
                  variants={letterVariants}
                >
                  {/* A soft brightness wave runs through the letters, left
                      to right, in place of a gradient shimmer. CSS keeps the
                      endless loop off the main thread. */}
                  <span
                    className="kokonut-ai-wave inline-block"
                    style={{ animationDelay: `${i * WAVE_STEP}s` }}
                  >
                    {char}
                  </span>
                </motion.span>
              ))}
            </motion.span>
          </AnimatePresence>
        </span>
      </MotionConfig>
      {showElapsed && (
        <span
          aria-hidden="true"
          className="font-medium text-base text-neutral-400 tabular-nums dark:text-neutral-500"
        >
          {seconds}s
        </span>
      )}
    </output>
  );
}
```


---

# AI Voice
> Voice input with a scrolling waveform, then a take you can play back, discard or send.

Source: https://kokonutui.com/docs/ai/ai-voice

## Installation

```bash
npx shadcn@latest add @kokonutui/ai-voice
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: AI Voice
 * @version: 2.1.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { ArrowUp, Mic, Pause, Play, X } from "lucide-react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";
import { useEffect, useRef, useState } from "react";
import { cn } from "@/lib/utils";

type Mode = "idle" | "recording" | "review";

const BAR_COUNT = 48;
// One extra bar waits off the right edge, so the row can slide a full bar
// before the samples shift and nothing pops in.
const BAR_IDS = Array.from({ length: BAR_COUNT + 1 }, (_, i) => `bar-${i}`);
const BAR_PITCH = 5; // bar width + gap, px
// A new sample enters on the right this often, so the history scrolls at
// BAR_PITCH / SAMPLE_MS px per ms.
const SAMPLE_MS = 70;
const REST_LEVEL = 0.12;
// Shape shown under reduced motion: still bars, no scrolling.
const STILL_LEVELS = BAR_IDS.map(
  (_, i) => 0.25 + 0.5 * Math.abs(Math.sin(i * 0.55) * Math.cos(i * 0.21))
);
const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";
const EDGE_MASK =
  "linear-gradient(to right, transparent, black 18%, black 92%, transparent)";

/**
 * Speech-like level without a microphone: syllables at about 4-5 per second,
 * grouped into words and phrases with pauses between them.
 */
function createVoiceSimulator() {
  let speaking = false;
  let switchAt = 0;
  let gate = 0;
  return (time: number) => {
    if (time >= switchAt) {
      speaking = !speaking;
      switchAt =
        time +
        (speaking ? 700 + Math.random() * 1600 : 180 + Math.random() * 500);
    }
    // The gate eases in and out, so words swell and fade instead of cutting.
    gate += ((speaking ? 1 : 0) - gate) * 0.35;
    const t = time / 1000;
    const syllable = Math.abs(
      Math.sin(t * Math.PI * 4.4 + Math.sin(t * 1.7) * 2)
    );
    const grain = 0.65 + Math.random() * 0.35;
    return REST_LEVEL + gate * syllable * grain * (1 - REST_LEVEL);
  };
}

/** Squeezes a whole take into BAR_COUNT bars, keeping each slice's peak. */
function condense(take: number[]) {
  if (take.length === 0) {
    return STILL_LEVELS.slice(0, BAR_COUNT);
  }
  return Array.from({ length: BAR_COUNT }, (_, i) => {
    const from = Math.floor((i / BAR_COUNT) * take.length);
    const to = Math.max(
      from + 1,
      Math.floor(((i + 1) / BAR_COUNT) * take.length)
    );
    return Math.max(REST_LEVEL, ...take.slice(from, to));
  });
}

const formatTime = (seconds: number) => {
  const whole = Math.floor(seconds);
  const mins = Math.floor(whole / 60);
  const secs = whole % 60;
  return `${mins.toString().padStart(2, "0")}:${secs.toString().padStart(2, "0")}`;
};

const setScales = (
  bars: (HTMLSpanElement | null)[],
  levels: readonly number[]
) => {
  bars.forEach((bar, i) => {
    if (bar) {
      bar.style.transform = `scaleY(${(levels[i] ?? REST_LEVEL).toFixed(3)})`;
    }
  });
};

type Face = "mic" | "stop" | "play" | "pause";

const mainLabelFor = (mode: Mode, playing: boolean) => {
  if (mode === "recording") {
    return "Stop recording";
  }
  if (mode === "review") {
    return playing ? "Pause playback" : "Play recording";
  }
  return "Start recording";
};

const timerText = (
  mode: Mode,
  seconds: number,
  duration: number,
  playing: boolean,
  playhead: number
) => {
  if (mode === "review") {
    return formatTime(playing || playhead > 0 ? playhead : duration);
  }
  return formatTime(mode === "recording" ? seconds : 0);
};

const FACE_CLASS =
  "absolute transition-[opacity,filter,scale] duration-200 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-opacity";
const faceState = (visible: boolean) =>
  visible ? "scale-100 opacity-100 blur-0" : "scale-50 opacity-0 blur-[3px]";

/**
 * Mic, stop, play and pause stay mounted and crossfade with a little blur,
 * so every swap reads as one control changing state.
 */
function ButtonFaces({ visible }: { visible: Record<Face, boolean> }) {
  const icon = "h-6 w-6 text-black/90 dark:text-white/90";
  return (
    <>
      <Mic
        aria-hidden="true"
        className={cn(FACE_CLASS, icon, faceState(visible.mic))}
      />
      <span
        aria-hidden="true"
        className={cn(
          FACE_CLASS,
          "h-5 w-5 rounded-[5px] bg-black dark:bg-white",
          faceState(visible.stop)
        )}
      />
      <Play
        aria-hidden="true"
        className={cn(
          FACE_CLASS,
          icon,
          "fill-current",
          faceState(visible.play)
        )}
      />
      <Pause
        aria-hidden="true"
        className={cn(
          FACE_CLASS,
          icon,
          "fill-current",
          faceState(visible.pause)
        )}
      />
    </>
  );
}

const ACTION_FOCUS =
  "focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-black/20 dark:focus-visible:ring-white/30";

function ReviewActions({
  onDiscard,
  onSend,
}: {
  onDiscard: () => void;
  onSend: () => void;
}) {
  return (
    <motion.div
      animate={{ opacity: 1, y: 0, filter: "blur(0px)" }}
      className="flex items-center gap-1"
      exit={{ opacity: 0, filter: "blur(2px)" }}
      initial={{ opacity: 0, y: 4, filter: "blur(2px)" }}
      transition={{ duration: 0.2, ease: [0.23, 1, 0.32, 1] }}
    >
      <button
        className={cn(
          "flex h-7 items-center gap-1 rounded-lg px-2 text-black/60 text-xs transition-colors duration-150 hover:bg-black/5 hover:text-black dark:text-white/60 dark:hover:bg-white/5 dark:hover:text-white",
          ACTION_FOCUS
        )}
        onClick={onDiscard}
        type="button"
      >
        <X aria-hidden="true" className="size-3.5" />
        Discard
      </button>
      <button
        className={cn(
          "flex h-7 items-center gap-1 rounded-lg bg-black px-2.5 text-white text-xs transition-colors duration-150 hover:bg-black/80 dark:bg-white dark:text-black dark:hover:bg-white/80",
          ACTION_FOCUS
        )}
        onClick={onSend}
        type="button"
      >
        Send
        <ArrowUp aria-hidden="true" className="size-3.5" />
      </button>
    </motion.div>
  );
}

interface AIVoiceProps {
  className?: string;
  /** Plays a record, review and send loop until the first click. */
  demo?: boolean;
  /**
   * Live input level from 0 to 1, e.g. from your own audio analyser. When
   * omitted, the waveform plays a simulated voice.
   */
  level?: number;
  /** Called with the new state when the user starts or stops recording. */
  onListeningChange?: (listening: boolean) => void;
  /** Called with the take's length in seconds when recording stops. */
  onStop?: (duration: number) => void;
  /** Called when the user sends the reviewed take. */
  onSend?: (duration: number) => void;
  /** Called when the user throws the take away. */
  onDiscard?: () => void;
}

export default function AI_Voice({
  className,
  demo = true,
  level,
  onListeningChange,
  onStop,
  onSend,
  onDiscard,
}: AIVoiceProps) {
  const [mode, setMode] = useState<Mode>("idle");
  const [isDemo, setIsDemo] = useState(demo);
  const [seconds, setSeconds] = useState(0);
  const [duration, setDuration] = useState(0);
  const [playing, setPlaying] = useState(false);
  const [playhead, setPlayhead] = useState(0);
  const shouldReduceMotion = useReducedMotion();

  const rootRef = useRef<HTMLDivElement>(null);
  const rowRef = useRef<HTMLDivElement>(null);
  const ringRef = useRef<HTMLSpanElement>(null);
  const playedRef = useRef<HTMLDivElement>(null);
  const barRefs = useRef<(HTMLSpanElement | null)[]>([]);
  const playedBarRefs = useRef<(HTMLSpanElement | null)[]>([]);
  const takeRef = useRef<number[]>([]);
  const startedAtRef = useRef(0);
  const levelRef = useRef(level);
  useEffect(() => {
    levelRef.current = level;
  }, [level]);

  const recording = mode === "recording";
  const reviewing = mode === "review";
  // The demo loop is not the user recording, so assistive tech only hears
  // about real actions.
  const announce = !isDemo;

  // Recording: one rAF loop writes transforms straight to the bars and the
  // ring, so a frame never re-renders React. It pauses offscreen.
  useEffect(() => {
    const bars = barRefs.current;
    const row = rowRef.current;
    const ring = ringRef.current;
    const root = rootRef.current;
    if (!(recording && row && ring && root)) {
      return;
    }
    takeRef.current = [];

    if (shouldReduceMotion) {
      setScales(bars, STILL_LEVELS);
      takeRef.current = STILL_LEVELS.slice();
      return;
    }

    const simulate = createVoiceSimulator();
    const samples = BAR_IDS.map(() => REST_LEVEL);
    let phase = 0;
    let smooth = 0;
    let last = performance.now();
    let frame = 0;

    const tick = (now: number) => {
      // Clamped so a backgrounded tab doesn't fast-forward on return.
      const dt = Math.min(now - last, 100);
      last = now;
      phase += dt / SAMPLE_MS;
      while (phase >= 1) {
        phase -= 1;
        const live = levelRef.current;
        const sample =
          live === undefined
            ? simulate(now)
            : Math.max(REST_LEVEL, Math.min(1, live));
        samples.shift();
        samples.push(sample);
        takeRef.current.push(sample);
      }
      row.style.transform = `translateX(${(-phase * BAR_PITCH).toFixed(2)}px)`;
      setScales(bars, samples);
      // The ring behind the button swells with the voice, smoothed so it
      // breathes rather than flickers.
      const latest = samples.at(-1) ?? REST_LEVEL;
      smooth += (latest - smooth) * 0.18;
      const lift = Math.max(0, smooth - REST_LEVEL);
      ring.style.transform = `scale(${(1 + lift * 0.22).toFixed(3)})`;
      ring.style.opacity = (0.4 + lift * 0.8).toFixed(3);
      frame = requestAnimationFrame(tick);
    };

    const start = () => {
      cancelAnimationFrame(frame);
      last = performance.now();
      frame = requestAnimationFrame(tick);
    };

    const observer = new IntersectionObserver(([entry]) => {
      if (entry.isIntersecting) {
        start();
      } else {
        cancelAnimationFrame(frame);
      }
    });
    observer.observe(root);
    start();

    return () => {
      observer.disconnect();
      cancelAnimationFrame(frame);
      ring.style.transform = "scale(1)";
      ring.style.opacity = "0";
    };
  }, [recording, shouldReduceMotion]);

  // Review shows the whole take squeezed into the row; idle lays it flat.
  // The bars carry a CSS transition outside recording, so both glide.
  useEffect(() => {
    const row = rowRef.current;
    if (recording || !row) {
      return;
    }
    row.style.transform = "translateX(0px)";
    const levels = reviewing
      ? condense(takeRef.current)
      : BAR_IDS.map(() => REST_LEVEL);
    setScales(barRefs.current, levels);
    setScales(playedBarRefs.current, levels);
  }, [recording, reviewing]);

  // Recording timer.
  useEffect(() => {
    if (!recording) {
      return;
    }
    setSeconds(0);
    startedAtRef.current = Date.now();
    const id = setInterval(() => {
      setSeconds(Math.floor((Date.now() - startedAtRef.current) / 1000));
    }, 250);
    return () => clearInterval(id);
  }, [recording]);

  // Playback: a playhead sweeps the take. There is no audio; it shows where
  // your own player is, or just previews the take in the demo.
  useEffect(() => {
    const played = playedRef.current;
    if (!(playing && played)) {
      return;
    }
    const length = Math.max(duration, 1) * 1000;
    const startedAt = performance.now();
    let frame = 0;
    const tick = (now: number) => {
      const progress = Math.min((now - startedAt) / length, 1);
      played.style.clipPath = `inset(0 ${((1 - progress) * 100).toFixed(2)}% 0 0)`;
      setPlayhead(progress * Math.max(duration, 1));
      if (progress < 1) {
        frame = requestAnimationFrame(tick);
      } else {
        setPlaying(false);
      }
    };
    frame = requestAnimationFrame(tick);
    return () => cancelAnimationFrame(frame);
  }, [playing, duration]);

  const startRecording = () => {
    setPlaying(false);
    setMode("recording");
    onListeningChange?.(true);
  };

  const stopRecording = () => {
    const taken = Math.max(
      (Date.now() - startedAtRef.current) / 1000,
      takeRef.current.length * (SAMPLE_MS / 1000)
    );
    setDuration(taken);
    setPlayhead(0);
    if (playedRef.current) {
      playedRef.current.style.clipPath = "inset(0 100% 0 0)";
    }
    setMode("review");
    onListeningChange?.(false);
    onStop?.(taken);
  };

  const finish = (sent: boolean) => {
    setPlaying(false);
    setMode("idle");
    if (sent) {
      onSend?.(duration);
    } else {
      onDiscard?.();
    }
  };

  const togglePlay = () => {
    if (!playing && playedRef.current) {
      playedRef.current.style.clipPath = "inset(0 100% 0 0)";
    }
    setPlaying((p) => !p);
  };

  // Demo: record, review with a playback sweep, send, rest. Ends on the
  // first press anywhere in the component.
  const hasPlayed = playhead > 0;
  const demoStepRef = useRef<() => void>(() => undefined);
  useEffect(() => {
    demoStepRef.current = () => {
      if (mode === "idle") {
        startRecording();
      } else if (mode === "recording") {
        stopRecording();
      } else if (hasPlayed) {
        finish(true);
      } else {
        togglePlay();
      }
    };
  });
  useEffect(() => {
    if (!isDemo || playing) {
      return;
    }
    const delays: Record<Mode, number> = {
      idle: 1200,
      recording: 3400,
      review: hasPlayed ? 900 : 500,
    };
    const id = setTimeout(() => demoStepRef.current(), delays[mode]);
    return () => clearTimeout(id);
  }, [isDemo, mode, hasPlayed, playing]);

  const endDemo = () => {
    if (isDemo) {
      setIsDemo(false);
      setPlaying(false);
      setMode("idle");
    }
  };

  const handleMainClick = () => {
    if (isDemo) {
      endDemo();
      startRecording();
    } else if (recording) {
      stopRecording();
    } else if (reviewing) {
      togglePlay();
    } else {
      startRecording();
    }
  };

  const faces: Record<Face, boolean> = {
    mic: mode === "idle",
    stop: recording,
    play: reviewing && !playing,
    pause: reviewing && playing,
  };
  const timerValue = timerText(mode, seconds, duration, playing, playhead);

  return (
    <div
      className={cn("w-full py-4", className)}
      onPointerDownCapture={endDemo}
      ref={rootRef}
    >
      <div className="relative mx-auto flex w-full max-w-xl flex-col items-center gap-2">
        <div className="relative">
          {/* Swells with the voice while recording. */}
          <span
            aria-hidden="true"
            className="pointer-events-none absolute inset-0 rounded-xl bg-black/5 opacity-0 dark:bg-white/5"
            ref={ringRef}
          />
          <button
            aria-label={mainLabelFor(mode, playing)}
            aria-pressed={recording && announce}
            className={cn(
              "relative flex h-16 w-16 items-center justify-center rounded-xl transition-colors duration-150 ease-out",
              "outline-hidden focus-visible:ring-2 focus-visible:ring-black/20 dark:focus-visible:ring-white/30",
              mode === "idle"
                ? "hover:bg-black/5 dark:hover:bg-white/5"
                : "bg-black/5 dark:bg-white/5"
            )}
            onClick={handleMainClick}
            type="button"
          >
            <ButtonFaces visible={faces} />
          </button>
        </div>

        <span
          className={cn(
            "font-mono text-sm tabular-nums transition-colors duration-300",
            mode === "idle"
              ? "text-black/30 dark:text-white/30"
              : "text-black/70 dark:text-white/70"
          )}
        >
          {timerValue}
        </span>

        {/* While recording, the newest sound enters on the right and the
            edges fade. In review the whole take sits still and a darker
            copy, clipped at the playhead, shows what has played. */}
        <div
          aria-hidden="true"
          className="relative h-8 w-60 overflow-hidden"
          style={{
            maskImage: recording ? EDGE_MASK : undefined,
            WebkitMaskImage: recording ? EDGE_MASK : undefined,
          }}
        >
          <div className="flex h-full items-center gap-[2px]" ref={rowRef}>
            {BAR_IDS.map((id, i) => (
              <span
                className={cn(
                  "h-full w-[3px] shrink-0 rounded-full",
                  recording
                    ? "bg-black/60 dark:bg-white/60"
                    : "bg-black/15 transition-transform duration-500 motion-reduce:transition-none dark:bg-white/15"
                )}
                key={id}
                ref={(el) => {
                  barRefs.current[i] = el;
                }}
                style={{
                  transform: `scaleY(${REST_LEVEL})`,
                  // Out of recording the bars settle right to left.
                  transitionDelay: recording
                    ? undefined
                    : `${(BAR_COUNT - i) * 6}ms`,
                  transitionTimingFunction: EASE_OUT,
                }}
              />
            ))}
          </div>
          <div
            className={cn(
              "absolute inset-0 flex items-center gap-[2px] transition-opacity duration-200",
              reviewing ? "opacity-100" : "opacity-0"
            )}
            ref={playedRef}
            style={{ clipPath: "inset(0 100% 0 0)" }}
          >
            {BAR_IDS.map((id, i) => (
              <span
                className="h-full w-[3px] shrink-0 rounded-full bg-black/70 dark:bg-white/70"
                key={id}
                ref={(el) => {
                  playedBarRefs.current[i] = el;
                }}
                style={{ transform: `scaleY(${REST_LEVEL})` }}
              />
            ))}
          </div>
        </div>

        <div className="relative flex h-7 items-center justify-center">
          <AnimatePresence initial={false} mode="popLayout">
            {reviewing ? (
              <ReviewActions
                key="actions"
                onDiscard={() => finish(false)}
                onSend={() => finish(true)}
              />
            ) : (
              <motion.span
                animate={{ opacity: 1, filter: "blur(0px)" }}
                className="text-black/70 text-xs dark:text-white/70"
                exit={{ opacity: 0, filter: "blur(2px)" }}
                initial={{ opacity: 0, filter: "blur(2px)" }}
                key="caption"
                transition={{ duration: 0.2, ease: [0.23, 1, 0.32, 1] }}
              >
                {recording ? "Listening..." : "Click to speak"}
              </motion.span>
            )}
          </AnimatePresence>
        </div>

        {/* <output> has the implicit role="status". It stays silent during
            the demo loop. */}
        <output aria-live={announce ? "polite" : "off"} className="sr-only">
          {announce && recording ? "Recording" : ""}
          {announce && reviewing ? "Recording ready to send" : ""}
        </output>
      </div>
    </div>
  );
}
```


---

# Background Paths
> A ribbon of lines in one color that keeps flowing at any size and parts around the cursor.

Source: https://kokonutui.com/docs/backgrounds/background-paths

## Installation

```bash
npx shadcn@latest add @kokonutui/background-paths
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Background Paths
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface BackgroundPathsProps {
  className?: string;
  /** Content shown over the lines. Pass `null` for a bare background. */
  children?: ReactNode;
  /** Number of lines, shared across the three depth layers. */
  count?: number;
  /** How far the ribbon fans out, as a share of the height. */
  spread?: number;
  /** Tilt of the ribbon, in degrees. */
  angle?: number;
  /** How fast the ribbon flows. 0 holds it still. */
  speed?: number;
  /** Part the lines around the cursor. */
  interactive?: boolean;
}

const SAMPLES = 64;
/** Lines reach this far past each side, so their ends never show. */
const OVERSCAN = 0.06;
const DRAW_MS = 1400;
const DRAW_STAGGER_MS = 40;
const PART_RADIUS = 150;
const PART_PUSH = 56;

interface Layer {
  width: number;
  opacity: number;
  /** Phase offset, so the layers don't sit on top of each other. */
  phase: number;
  /** Flow speed relative to the others: the front layer moves fastest. */
  pace: number;
  /** How much the cursor parts this layer. */
  part: number;
}

const LAYERS: Layer[] = [
  { width: 1, opacity: 0.16, phase: 0.6, pace: 0.7, part: 0.45 },
  { width: 1.25, opacity: 0.26, phase: 0.3, pace: 0.85, part: 0.75 },
  { width: 1.5, opacity: 0.4, phase: 0, pace: 1, part: 1 },
];

interface Pointer {
  x: number;
  y: number;
  /** Eases to 1 while the mouse is over the hero, back to 0 when it leaves. */
  amount: number;
  on: boolean;
}

interface Frame {
  width: number;
  height: number;
  time: number;
  /** 0 to 1: how much of each line the entrance has drawn. */
  drawn: number[];
  pointer: Pointer;
}

interface Shape {
  count: number;
  spread: number;
  slope: number;
  interactive: boolean;
}

/**
 * Height of line `s` (-0.5 to 0.5 across the ribbon) at `u` (0 to 1 along
 * it). The ribbon turns over where `twist` crosses zero; that point and the
 * ribbon's curve both slide slowly with time, so the lines keep flowing.
 */
function lineY(
  s: number,
  u: number,
  layer: Layer,
  frame: Frame,
  shape: Shape,
  band: number
) {
  const t = frame.time * layer.pace;
  const x = u * frame.width;
  const center =
    frame.height * 0.5 +
    shape.slope * (x - frame.width / 2) +
    band *
      0.1 *
      Math.sin(Math.PI * 2 * (0.75 * u + 0.1) + layer.phase + t * 0.35);
  const turn = 0.22 + 0.09 * Math.sin(t * 0.21 + layer.phase);
  const breathe = 0.3 * Math.sin(t * 0.5 + s * 4 + layer.phase);
  const twist = Math.cos(
    Math.PI * (u - turn) + s * (0.6 + breathe) + layer.phase
  );
  return center + s * shape.spread * band * twist;
}

/** Push a point away from the cursor, vertically, with a soft falloff. */
function part(x: number, y: number, frame: Frame, strength: number) {
  const { pointer } = frame;
  if (pointer.amount < 0.001) {
    return y;
  }
  const dx = x - pointer.x;
  const dy = y - pointer.y;
  const falloff = Math.exp(-(dx * dx + dy * dy) / (PART_RADIUS * PART_RADIUS));
  // A soft sign, so lines right under the cursor split smoothly, not snap.
  const side = dy / (Math.abs(dy) + 24);
  return y + side * falloff * PART_PUSH * strength * pointer.amount;
}

function drawLines(
  ctx: CanvasRenderingContext2D,
  frame: Frame,
  shape: Shape,
  color: string
) {
  const { width, height } = frame;
  ctx.clearRect(0, 0, width, height);
  ctx.strokeStyle = color;
  ctx.lineCap = "round";
  ctx.lineJoin = "round";
  // On tall, narrow screens a full-height ribbon turns too steeply to read,
  // so its height is capped relative to the width.
  const band = Math.min(height, width * 1.1);
  const perLayer = Math.max(1, Math.round(shape.count / LAYERS.length));
  const xs = new Float32Array(SAMPLES + 1);
  const ys = new Float32Array(SAMPLES + 1);

  LAYERS.forEach((layer, layerIndex) => {
    ctx.lineWidth = layer.width;
    for (let i = 0; i < perLayer; i++) {
      const drawn = frame.drawn[layerIndex * perLayer + i] ?? 1;
      if (drawn <= 0) {
        continue;
      }
      const s = perLayer === 1 ? 0 : i / (perLayer - 1) - 0.5;
      const last = Math.max(1, Math.ceil(SAMPLES * drawn));
      for (let k = 0; k <= last; k++) {
        const u = -OVERSCAN + (k / SAMPLES) * (1 + OVERSCAN * 2);
        const x = u * width;
        const y = lineY(s, u, layer, frame, shape, band);
        xs[k] = x;
        ys[k] = shape.interactive ? part(x, y, frame, layer.part) : y;
      }
      // The ribbon's edges fade, its middle carries the weight.
      ctx.globalAlpha = layer.opacity * (0.45 + 0.55 * (1 - Math.abs(s) * 2));
      ctx.beginPath();
      ctx.moveTo(xs[0], ys[0]);
      // Curves through the midpoints keep the line smooth at any sampling.
      for (let k = 1; k < last; k++) {
        const mx = (xs[k] + xs[k + 1]) / 2;
        const my = (ys[k] + ys[k + 1]) / 2;
        ctx.quadraticCurveTo(xs[k], ys[k], mx, my);
      }
      ctx.lineTo(xs[last], ys[last]);
      ctx.stroke();
    }
  });
  ctx.globalAlpha = 1;
}

const EASE_OUT = (t: number) => 1 - (1 - t) ** 3;

export default function BackgroundPaths({
  className,
  children,
  count = 42,
  spread = 1,
  angle = -8,
  speed = 1,
  interactive = true,
}: BackgroundPathsProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const ctx = canvas?.getContext("2d");
    if (!(root && canvas && ctx)) {
      return;
    }
    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const shape: Shape = {
      count,
      spread,
      slope: Math.tan((angle * Math.PI) / 180),
      interactive: interactive && !reduceMotion,
    };
    const perLayer = Math.max(1, Math.round(count / LAYERS.length));
    const total = perLayer * LAYERS.length;
    const frame: Frame = {
      width: 0,
      height: 0,
      // Start mid-flow, so the first frame isn't the same every visit.
      time: 40,
      drawn: new Array(total).fill(reduceMotion ? 1 : 0),
      pointer: { x: 0, y: 0, amount: 0, on: false },
    };
    let color = getComputedStyle(canvas).color;
    let start = 0;
    let last = 0;
    let raf = 0;
    let visible = true;

    const paint = () => drawLines(ctx, frame, shape, color);

    const resize = () => {
      const rect = canvas.getBoundingClientRect();
      const dpr = Math.min(window.devicePixelRatio || 1, 2);
      frame.width = rect.width;
      frame.height = rect.height;
      canvas.width = Math.round(rect.width * dpr);
      canvas.height = Math.round(rect.height * dpr);
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      paint();
    };

    const loop = (now: number) => {
      raf = 0;
      if (!start) {
        start = now;
        last = now;
      }
      const dt = Math.min((now - last) / 1000, 0.05);
      last = now;
      frame.time += dt * speed;
      // The entrance draws each line on once, left to right, staggered.
      const elapsed = now - start;
      for (let i = 0; i < frame.drawn.length; i++) {
        if (frame.drawn[i] < 1) {
          const local = (elapsed - (i % perLayer) * DRAW_STAGGER_MS) / DRAW_MS;
          frame.drawn[i] = EASE_OUT(Math.min(Math.max(local, 0), 1));
        }
      }
      const { pointer } = frame;
      pointer.amount += ((pointer.on ? 1 : 0) - pointer.amount) * 0.08;
      paint();
      const settling =
        frame.drawn.some((d) => d < 1) ||
        (pointer.amount > 0.001 && !pointer.on) ||
        pointer.on;
      if (visible && (speed > 0 || settling)) {
        raf = requestAnimationFrame(loop);
      }
    };
    const play = () => {
      if (!raf && visible && !reduceMotion) {
        last = performance.now();
        raf = requestAnimationFrame(loop);
      }
    };

    resize();
    canvas.style.opacity = "1";
    const resizeObserver = new ResizeObserver(resize);
    resizeObserver.observe(canvas);
    const intersection = new IntersectionObserver(([entry]) => {
      visible = entry.isIntersecting && !document.hidden;
      if (visible) {
        play();
      }
    });
    intersection.observe(root);
    const onVisibility = () => {
      visible = !document.hidden;
      if (visible) {
        play();
      }
    };
    document.addEventListener("visibilitychange", onVisibility);
    // Follow theme changes, which only change the inherited text color.
    const colorTimer = window.setInterval(() => {
      const next = getComputedStyle(canvas).color;
      if (next !== color) {
        color = next;
        paint();
      }
    }, 500);

    const onMove = (event: PointerEvent) => {
      if (event.pointerType !== "mouse" || !shape.interactive) {
        return;
      }
      const rect = canvas.getBoundingClientRect();
      frame.pointer.x = event.clientX - rect.left;
      frame.pointer.y = event.clientY - rect.top;
      frame.pointer.on = true;
      play();
    };
    const onLeave = () => {
      frame.pointer.on = false;
      play();
    };
    root.addEventListener("pointermove", onMove);
    root.addEventListener("pointerleave", onLeave);
    play();

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      window.clearInterval(colorTimer);
      root.removeEventListener("pointermove", onMove);
      root.removeEventListener("pointerleave", onLeave);
    };
  }, [count, spread, angle, speed, interactive]);

  return (
    <div
      className={cn(
        "relative flex min-h-[560px] w-full items-center justify-center overflow-hidden bg-white text-zinc-900 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={rootRef}
    >
      {/* Faded at the top and bottom, and quieter behind centered content. */}
      <div
        aria-hidden="true"
        className="pointer-events-none absolute inset-0"
        style={{
          maskImage:
            "linear-gradient(to bottom, transparent, #000 15%, #000 85%, transparent), radial-gradient(ellipse 40% 32% at 50% 50%, rgb(0 0 0 / 0.3), #000)",
          maskComposite: "intersect",
          WebkitMaskComposite: "source-in",
        }}
      >
        <canvas
          className="h-full w-full opacity-0 transition-opacity duration-500 ease-out"
          ref={canvasRef}
        />
      </div>
      {children === undefined ? <DefaultContent /> : children}
    </div>
  );
}

function DefaultContent() {
  return (
    <div className="relative flex max-w-xl flex-col items-center gap-4 px-6 text-center">
      <h1 className="font-semibold text-4xl tracking-tight sm:text-5xl">
        Calm by default
      </h1>
      <p className="max-w-sm text-base text-zinc-500 dark:text-zinc-400">
        A ribbon of lines that keeps flowing in one color, at any size. Move the
        cursor through it and the lines part around you.
      </p>
    </div>
  );
}
```


---

# Dot Field
> A halftone dot membrane that ripples behind a swipe and rings out from a click, built with React and Canvas.

Source: https://kokonutui.com/docs/backgrounds/dot-field

## Installation

```bash
npx shadcn@latest add @kokonutui/dot-field
```

## Source

```tsx
// biome-ignore-all lint/suspicious/noBitwiseOperators: the noise hash is bit arithmetic.
"use client";

/**
 * @author: @dorianbaffier
 * @description: Dot Field
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface DotFieldProps {
  className?: string;
  /** Content shown over the field. Pass `null` for a bare background. */
  children?: ReactNode;
  /** Distance between dots, in px. */
  spacing?: number;
  /** Let a swipe push the dots and a click send a shockwave. */
  interactive?: boolean;
  /** Seed for the halftone pattern, so a page always opens on the same one. */
  seed?: number;
}

// Width of a light or dark patch in the idle halftone, in px.
const NOISE_SCALE = 240;
// How fast the halftone pattern drifts through time.
const NOISE_SPEED = 0.07;
// The noise is sampled on every third dot and blended in between.
const TONE_STEP = 3;
// The idle drift is slow; a frame every 33ms is plenty for it.
const IDLE_FRAME_MS = 33;
// The membrane. Each dot is pulled back to its rest point (ANCHOR), towards
// its four neighbours (COUPLING, which makes a disturbance travel as a wave)
// and loses speed to DAMPING. Units are per second squared.
const ANCHOR = 26;
const COUPLING = 340;
const DAMPING = 2.4;
// Physics runs in fixed steps so the springs behave the same at any refresh
// rate.
const STEP = 1 / 120;
// The pointer: radius it reaches (px), how much of its velocity it hands to
// the dots it passes (per second), and the fastest swipe it counts (px/s).
const POINTER_RADIUS = 72;
const POINTER_GAIN = 14;
const POINTER_MAX_SPEED = 2600;
// Share of the swipe speed that also pushes dots sideways, out of its path,
// so the wake opens into a V like water behind a boat.
const POINTER_PART = 0.45;
// A click: how fast the ring travels (px/s), how thick it is (px), how hard
// it shoves (px/s²) and how long it lives (s).
const SHOCK_SPEED = 620;
const SHOCK_WIDTH = 34;
const SHOCK_FORCE = 5200;
const SHOCK_LIFE = 1.3;
// Squeezed dots grow and stretched ones shrink, so the wake reads as a band
// of darker and lighter tone, like ink in a halftone print.
const COMPRESSION_GAIN = 3;
// Dot sizes are snapped to this many steps; each step is one path.
const BUCKETS = 10;
// Below these the field counts as settled and the physics sleeps.
const REST_SPEED = 2;
const REST_OFFSET = 0.15;

interface Shock {
  x: number;
  y: number;
  age: number;
}

interface Pointer {
  x: number;
  y: number;
  lastX: number;
  lastY: number;
  inside: boolean;
}

/** Seeded 3D gradient noise (Ken Perlin's improved noise), about -1 to 1. */
function createNoise(seed: number) {
  const p = Array.from({ length: 256 }, (_, i) => i);
  let state = seed >>> 0 || 1;
  const random = () => {
    state = (state * 1_664_525 + 1_013_904_223) >>> 0;
    return state / 4_294_967_296;
  };
  for (let i = 255; i > 0; i--) {
    const j = Math.floor(random() * (i + 1));
    [p[i], p[j]] = [p[j], p[i]];
  }
  const perm = new Uint8Array(512);
  for (let i = 0; i < 512; i++) {
    perm[i] = p[i & 255];
  }
  const fade = (t: number) => t * t * t * (t * (t * 6 - 15) + 10);
  const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
  const grad = (hash: number, x: number, y: number, z: number) => {
    const h = hash & 15;
    const u = h < 8 ? x : y;
    let v = z;
    if (h < 4) {
      v = y;
    } else if (h === 12 || h === 14) {
      v = x;
    }
    return ((h & 1) === 0 ? u : -u) + ((h & 2) === 0 ? v : -v);
  };

  return (x: number, y: number, z: number) => {
    const X = Math.floor(x) & 255;
    const Y = Math.floor(y) & 255;
    const Z = Math.floor(z) & 255;
    const fx = x - Math.floor(x);
    const fy = y - Math.floor(y);
    const fz = z - Math.floor(z);
    const u = fade(fx);
    const v = fade(fy);
    const w = fade(fz);
    const A = perm[X] + Y;
    const AA = perm[A] + Z;
    const AB = perm[A + 1] + Z;
    const B = perm[X + 1] + Y;
    const BA = perm[B] + Z;
    const BB = perm[B + 1] + Z;
    return lerp(
      lerp(
        lerp(grad(perm[AA], fx, fy, fz), grad(perm[BA], fx - 1, fy, fz), u),
        lerp(
          grad(perm[AB], fx, fy - 1, fz),
          grad(perm[BB], fx - 1, fy - 1, fz),
          u
        ),
        v
      ),
      lerp(
        lerp(
          grad(perm[AA + 1], fx, fy, fz - 1),
          grad(perm[BA + 1], fx - 1, fy, fz - 1),
          u
        ),
        lerp(
          grad(perm[AB + 1], fx, fy - 1, fz - 1),
          grad(perm[BB + 1], fx - 1, fy - 1, fz - 1),
          u
        ),
        v
      ),
      w
    );
  };
}

/** The grid of dots and the state of every spring, in flat arrays. */
interface Field {
  cols: number;
  rows: number;
  spacing: number;
  originX: number;
  originY: number;
  /** Idle size of each dot from the noise, 0 to 1. */
  tone: Float32Array;
  /** The noise on a coarser grid, blended into `tone`. */
  coarse: Float32Array;
  ox: Float32Array;
  oy: Float32Array;
  vx: Float32Array;
  vy: Float32Array;
  ax: Float32Array;
  ay: Float32Array;
}

function createField(width: number, height: number, spacing: number): Field {
  // One extra dot past each edge, so the membrane has no visible border.
  const cols = Math.ceil(width / spacing) + 3;
  const rows = Math.ceil(height / spacing) + 3;
  const size = cols * rows;
  return {
    cols,
    rows,
    spacing,
    originX: (width - (cols - 1) * spacing) / 2,
    originY: (height - (rows - 1) * spacing) / 2,
    tone: new Float32Array(size),
    coarse: new Float32Array(
      (Math.ceil((cols - 1) / TONE_STEP) + 1) *
        (Math.ceil((rows - 1) / TONE_STEP) + 1)
    ),
    ox: new Float32Array(size),
    oy: new Float32Array(size),
    vx: new Float32Array(size),
    vy: new Float32Array(size),
    ax: new Float32Array(size),
    ay: new Float32Array(size),
  };
}

/**
 * The idle halftone. The noise is smooth over a few hundred px, so it is
 * sampled on every TONE_STEP-th dot and blended in between, which costs a
 * ninth of sampling every dot.
 */
function sampleTone(
  field: Field,
  noise: (x: number, y: number, z: number) => number,
  time: number
) {
  const { cols, rows, spacing, originX, originY, tone, coarse } = field;
  const z = time * NOISE_SPEED;
  const step = spacing * TONE_STEP;
  const coarseCols = Math.ceil((cols - 1) / TONE_STEP) + 1;
  const coarseRows = Math.ceil((rows - 1) / TONE_STEP) + 1;
  for (let j = 0; j < coarseRows; j++) {
    const ny = (originY + j * step) / NOISE_SCALE;
    for (let i = 0; i < coarseCols; i++) {
      const nx = (originX + i * step) / NOISE_SCALE;
      const n =
        noise(nx, ny, z) * 0.75 +
        noise(nx * 2.1 + 9.3, ny * 2.1 + 3.7, z * 1.3) * 0.25;
      coarse[j * coarseCols + i] = Math.min(1, Math.max(0, 0.5 + n * 1.1));
    }
  }
  for (let j = 0; j < rows; j++) {
    const cj = Math.min(Math.floor(j / TONE_STEP), coarseRows - 2);
    const fy = j / TONE_STEP - cj;
    for (let i = 0; i < cols; i++) {
      const ci = Math.min(Math.floor(i / TONE_STEP), coarseCols - 2);
      const fx = i / TONE_STEP - ci;
      const a = cj * coarseCols + ci;
      const top = coarse[a] + (coarse[a + 1] - coarse[a]) * fx;
      const bottom =
        coarse[a + coarseCols] +
        (coarse[a + coarseCols + 1] - coarse[a + coarseCols]) * fx;
      tone[j * cols + i] = top + (bottom - top) * fy;
    }
  }
}

/** Sum of the four neighbours; past the border counts as a still dot. */
function neighbours(
  values: Float32Array,
  field: Field,
  i: number,
  j: number
): number {
  const { cols, rows } = field;
  const k = j * cols + i;
  let sum = 0;
  if (i > 0) {
    sum += values[k - 1];
  }
  if (i < cols - 1) {
    sum += values[k + 1];
  }
  if (j > 0) {
    sum += values[k - cols];
  }
  if (j < rows - 1) {
    sum += values[k + cols];
  }
  return sum;
}

/** Spring force on every dot: back to rest, towards neighbours, damping. */
function accelerate(field: Field) {
  const { cols, rows, ox, oy, vx, vy, ax, ay } = field;
  for (let j = 0; j < rows; j++) {
    for (let i = 0; i < cols; i++) {
      const k = j * cols + i;
      const sx = neighbours(ox, field, i, j);
      const sy = neighbours(oy, field, i, j);
      ax[k] += -ANCHOR * ox[k] + COUPLING * (sx - 4 * ox[k]) - DAMPING * vx[k];
      ay[k] += -ANCHOR * oy[k] + COUPLING * (sy - 4 * oy[k]) - DAMPING * vy[k];
    }
  }
}

/** A ring travelling out from each click, shoving the dots it crosses. */
function applyShocks(field: Field, shocks: Shock[]) {
  const { cols, rows, spacing, originX, originY, ax, ay } = field;
  for (const shock of shocks) {
    const reach = shock.age * SHOCK_SPEED;
    const fade = 1 - shock.age / SHOCK_LIFE;
    const force = SHOCK_FORCE * fade * fade;
    const outer = reach + SHOCK_WIDTH;
    const inner = Math.max(0, reach - SHOCK_WIDTH);
    // Only the rows and columns the ring's box touches.
    const i0 = Math.max(0, Math.floor((shock.x - outer - originX) / spacing));
    const i1 = Math.min(
      cols - 1,
      Math.ceil((shock.x + outer - originX) / spacing)
    );
    const j0 = Math.max(0, Math.floor((shock.y - outer - originY) / spacing));
    const j1 = Math.min(
      rows - 1,
      Math.ceil((shock.y + outer - originY) / spacing)
    );
    for (let j = j0; j <= j1; j++) {
      const dy = originY + j * spacing - shock.y;
      for (let i = i0; i <= i1; i++) {
        const dx = originX + i * spacing - shock.x;
        const dist = Math.hypot(dx, dy);
        if (dist < inner || dist > outer || dist === 0) {
          continue;
        }
        const band = 1 - Math.abs(dist - reach) / SHOCK_WIDTH;
        const k = j * cols + i;
        ax[k] += (dx / dist) * force * band;
        ay[k] += (dy / dist) * force * band;
      }
    }
  }
}

/**
 * The pointer hands part of its velocity to the dots near the path it took
 * since the last frame. A slow drift barely stirs them; a fast swipe drags
 * a strip of the membrane along, and the springs turn that into a wake.
 */
function applyPointer(field: Field, pointer: Pointer, dt: number) {
  const segX = pointer.x - pointer.lastX;
  const segY = pointer.y - pointer.lastY;
  pointer.lastX = pointer.x;
  pointer.lastY = pointer.y;
  const length = Math.hypot(segX, segY);
  if (!pointer.inside || length < 0.5 || dt <= 0) {
    return false;
  }
  const speed = Math.min(length / dt, POINTER_MAX_SPEED);
  const pvx = (segX / length) * speed;
  const pvy = (segY / length) * speed;
  const { cols, rows, spacing, originX, originY, vx, vy } = field;
  const startX = pointer.x - segX;
  const startY = pointer.y - segY;
  const minX = Math.min(startX, pointer.x) - POINTER_RADIUS;
  const maxX = Math.max(startX, pointer.x) + POINTER_RADIUS;
  const minY = Math.min(startY, pointer.y) - POINTER_RADIUS;
  const maxY = Math.max(startY, pointer.y) + POINTER_RADIUS;
  const i0 = Math.max(0, Math.floor((minX - originX) / spacing));
  const i1 = Math.min(cols - 1, Math.ceil((maxX - originX) / spacing));
  const j0 = Math.max(0, Math.floor((minY - originY) / spacing));
  const j1 = Math.min(rows - 1, Math.ceil((maxY - originY) / spacing));
  const lengthSq = length * length;
  const gain = Math.min(1, POINTER_GAIN * dt);
  for (let j = j0; j <= j1; j++) {
    const py = originY + j * spacing;
    for (let i = i0; i <= i1; i++) {
      const px = originX + i * spacing;
      // Distance from the dot to the swipe segment.
      const t = Math.min(
        1,
        Math.max(0, ((px - startX) * segX + (py - startY) * segY) / lengthSq)
      );
      const awayX = px - startX - segX * t;
      const awayY = py - startY - segY * t;
      const dist = Math.hypot(awayX, awayY);
      if (dist >= POINTER_RADIUS) {
        continue;
      }
      const falloff = 1 - dist / POINTER_RADIUS;
      const k = j * cols + i;
      const amount = gain * falloff * falloff;
      const side = dist > 0 ? (speed * POINTER_PART) / dist : 0;
      vx[k] += (pvx + awayX * side - vx[k]) * amount;
      vy[k] += (pvy + awayY * side - vy[k]) * amount;
    }
  }
  return true;
}

/** One fixed physics step. Returns whether anything is still moving. */
function integrate(field: Field, shocks: Shock[], h: number) {
  const { ox, oy, vx, vy, ax, ay } = field;
  ax.fill(0);
  ay.fill(0);
  applyShocks(field, shocks);
  accelerate(field);
  let moving = false;
  for (let k = 0; k < ox.length; k++) {
    vx[k] += ax[k] * h;
    vy[k] += ay[k] * h;
    ox[k] += vx[k] * h;
    oy[k] += vy[k] * h;
    if (
      !moving &&
      (Math.abs(vx[k]) > REST_SPEED ||
        Math.abs(vy[k]) > REST_SPEED ||
        Math.abs(ox[k]) > REST_OFFSET ||
        Math.abs(oy[k]) > REST_OFFSET)
    ) {
      moving = true;
    }
  }
  return moving;
}

/** How much the membrane is squeezed (+) or stretched (-) at one dot. */
function compression(field: Field, i: number, j: number) {
  const { cols, rows, spacing, ox, oy } = field;
  const k = j * cols + i;
  const left = i > 0 ? ox[k - 1] : 0;
  const right = i < cols - 1 ? ox[k + 1] : 0;
  const up = j > 0 ? oy[k - cols] : 0;
  const down = j < rows - 1 ? oy[k + cols] : 0;
  return -(right - left + down - up) / (2 * spacing);
}

/**
 * Draw every dot. Sizes are snapped to a few steps and each step is one
 * path, so the whole field is a handful of fills instead of thousands.
 */
function draw(
  ctx: CanvasRenderingContext2D,
  field: Field,
  size: { width: number; height: number; color: string },
  moving: boolean
) {
  const { cols, rows, spacing, originX, originY, tone, ox, oy } = field;
  const maxRadius = spacing * 0.42;
  const paths = Array.from({ length: BUCKETS }, () => new Path2D());
  const filled = new Uint8Array(BUCKETS);
  for (let j = 0; j < rows; j++) {
    for (let i = 0; i < cols; i++) {
      const k = j * cols + i;
      let amount = 0.12 + 0.6 * tone[k];
      if (moving) {
        amount *= 1 + COMPRESSION_GAIN * compression(field, i, j);
      }
      const bucket = Math.round(
        Math.min(1, Math.max(0, amount)) * (BUCKETS - 1)
      );
      if (bucket === 0) {
        continue;
      }
      const radius = (maxRadius * bucket) / (BUCKETS - 1);
      const x = originX + i * spacing + ox[k];
      const y = originY + j * spacing + oy[k];
      const path = paths[bucket];
      path.moveTo(x + radius, y);
      path.arc(x, y, radius, 0, Math.PI * 2);
      filled[bucket] = 1;
    }
  }
  ctx.clearRect(0, 0, size.width, size.height);
  ctx.fillStyle = size.color;
  for (let b = 1; b < BUCKETS; b++) {
    if (filled[b]) {
      // Larger dots are a touch more opaque, which deepens the tone range.
      ctx.globalAlpha = 0.2 + (0.32 * b) / (BUCKETS - 1);
      ctx.fill(paths[b]);
    }
  }
  ctx.globalAlpha = 1;
}

export default function DotField({
  className,
  children,
  spacing = 16,
  interactive = true,
  seed = 7,
}: DotFieldProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const ctx = canvas?.getContext("2d");
    if (!(root && canvas && ctx)) {
      return;
    }

    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const noise = createNoise(seed);
    const gap = Math.max(6, spacing);
    const size = { width: 0, height: 0, color: "" };
    let field = createField(0, 0, gap);

    const pointer: Pointer = {
      x: 0,
      y: 0,
      lastX: 0,
      lastY: 0,
      inside: false,
    };
    const shocks: Shock[] = [];
    let time = 0;
    let last = 0;
    let lastTone = 0;
    let carry = 0;
    // What the last physics step found. Frames shorter than STEP (144Hz
    // screens) run no step, so they go by this rather than settle early.
    let stirring = false;
    let awake = false;
    let raf = 0;
    let visible = true;

    const resize = () => {
      const rect = canvas.getBoundingClientRect();
      const dpr = Math.min(window.devicePixelRatio || 1, 2);
      size.width = rect.width;
      size.height = rect.height;
      canvas.width = Math.round(size.width * dpr);
      canvas.height = Math.round(size.height * dpr);
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      size.color = getComputedStyle(canvas).color;
      field = createField(size.width, size.height, gap);
      sampleTone(field, noise, time);
      awake = false;
    };

    const physics = (dt: number) => {
      const pushed = applyPointer(field, pointer, dt);
      carry = Math.min(carry + dt, STEP * 6);
      while (carry >= STEP) {
        carry -= STEP;
        for (const shock of shocks) {
          shock.age += STEP;
        }
        while (shocks.length > 0 && shocks[0].age > SHOCK_LIFE) {
          shocks.shift();
        }
        stirring = integrate(field, shocks, STEP);
      }
      if (!(pushed || stirring || shocks.length > 0)) {
        // Settled: put every dot exactly home and let the physics sleep.
        field.ox.fill(0);
        field.oy.fill(0);
        field.vx.fill(0);
        field.vy.fill(0);
        awake = false;
      }
    };

    const frame = (now: number) => {
      raf = 0;
      if (!visible) {
        return;
      }
      const dt = last ? Math.min((now - last) / 1000, 0.05) : 0;
      last = now;
      time += dt;
      const wasAwake = awake;
      if (awake) {
        physics(dt);
      }
      const toneDue = now - lastTone >= IDLE_FRAME_MS;
      if (toneDue) {
        sampleTone(field, noise, time);
        lastTone = now;
      }
      // The drift alone gets about 30 frames a second; a wake gets every one.
      if (wasAwake || toneDue) {
        draw(ctx, field, size, wasAwake);
      }
      raf = requestAnimationFrame(frame);
    };

    const start = () => {
      if (!raf && visible && !reduceMotion) {
        last = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    const wake = () => {
      if (!awake) {
        awake = true;
        carry = 0;
        stirring = true;
      }
      start();
    };

    resize();
    draw(ctx, field, size, false);
    canvas.style.opacity = "1";
    start();

    const redraw = () => {
      resize();
      draw(ctx, field, size, false);
    };
    const resizeObserver = new ResizeObserver(redraw);
    resizeObserver.observe(canvas);

    // Moving the window to a screen with another pixel ratio doesn't resize
    // the canvas, so watch the ratio too or the dots go soft.
    let dprQuery: MediaQueryList | null = null;
    const watchDpr = () => {
      dprQuery?.removeEventListener("change", onDpr);
      dprQuery = window.matchMedia(
        `(resolution: ${window.devicePixelRatio}dppx)`
      );
      dprQuery.addEventListener("change", onDpr);
    };
    const onDpr = () => {
      redraw();
      watchDpr();
    };
    watchDpr();

    // Stop drawing entirely while the field is scrolled away or the tab is
    // in the background.
    let onScreen = true;
    const updateVisible = () => {
      visible = onScreen && document.visibilityState === "visible";
      if (visible) {
        start();
      }
    };
    const intersection = new IntersectionObserver(([entry]) => {
      onScreen = entry.isIntersecting;
      updateVisible();
    });
    intersection.observe(root);
    document.addEventListener("visibilitychange", updateVisible);

    // Follow light and dark mode without asking the app for a theme. Only
    // checked while the field is on screen.
    const colorTimer = window.setInterval(() => {
      if (!visible) {
        return;
      }
      const next = getComputedStyle(canvas).color;
      if (next !== size.color) {
        size.color = next;
        if (reduceMotion) {
          draw(ctx, field, size, false);
        }
      }
    }, 500);

    const local = (event: PointerEvent) => {
      const rect = canvas.getBoundingClientRect();
      return { x: event.clientX - rect.left, y: event.clientY - rect.top };
    };
    const onMove = (event: PointerEvent) => {
      const point = local(event);
      if (!pointer.inside) {
        // Start from where the pointer came in, not where it last left.
        pointer.lastX = point.x;
        pointer.lastY = point.y;
        pointer.inside = true;
      }
      pointer.x = point.x;
      pointer.y = point.y;
      if (
        Math.abs(pointer.x - pointer.lastX) > 0.5 ||
        Math.abs(pointer.y - pointer.lastY) > 0.5
      ) {
        wake();
      }
    };
    const onLeave = () => {
      pointer.inside = false;
    };
    const onDown = (event: PointerEvent) => {
      // Clicks on the content (links, buttons) are not meant for the field,
      // and neither are right or middle clicks.
      if (
        event.button !== 0 ||
        (event.target as HTMLElement).closest(
          "a, button, input, textarea, select, label, [role='button']"
        )
      ) {
        return;
      }
      const point = local(event);
      pointer.x = point.x;
      pointer.y = point.y;
      pointer.lastX = point.x;
      pointer.lastY = point.y;
      pointer.inside = true;
      shocks.push({ ...point, age: 0 });
      if (shocks.length > 3) {
        shocks.shift();
      }
      wake();
    };
    if (interactive && !reduceMotion) {
      root.addEventListener("pointermove", onMove);
      root.addEventListener("pointerleave", onLeave);
      root.addEventListener("pointerdown", onDown);
    }

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      dprQuery?.removeEventListener("change", onDpr);
      intersection.disconnect();
      document.removeEventListener("visibilitychange", updateVisible);
      window.clearInterval(colorTimer);
      root.removeEventListener("pointermove", onMove);
      root.removeEventListener("pointerleave", onLeave);
      root.removeEventListener("pointerdown", onDown);
    };
  }, [spacing, interactive, seed]);

  return (
    <div
      className={cn(
        "relative flex min-h-[560px] w-full items-center justify-center overflow-hidden bg-white text-zinc-900 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={rootRef}
    >
      {/* Faded out at the edges so the field sits into the page around it. */}
      <div aria-hidden="true" className="pointer-events-none absolute inset-0">
        <canvas
          className="h-full w-full opacity-0 transition-opacity duration-500 ease-out"
          ref={canvasRef}
          style={{
            // Fade at the edges, and quieter in the middle where the
            // content usually sits so text stays easy to read.
            maskImage:
              "radial-gradient(ellipse 75% 70% at 50% 50%, #000 40%, transparent 100%), radial-gradient(ellipse 34% 22% at 50% 50%, rgb(0 0 0 / 0.35), #000 100%)",
            maskComposite: "intersect",
          }}
        />
      </div>
      {children === undefined ? <DefaultContent /> : children}
    </div>
  );
}

function DefaultContent() {
  return (
    <div className="relative flex max-w-xl flex-col items-center gap-4 px-6 text-center">
      <h1 className="font-semibold text-4xl tracking-tight sm:text-5xl">
        Leave a mark
      </h1>
      <p className="max-w-sm text-base text-zinc-500 dark:text-zinc-400">
        A halftone membrane. Swipe fast to leave a wake, click to send a
        shockwave through it.
      </p>
    </div>
  );
}
```


---

# Drape Background
> A pleated curtain in a breeze that you can push and pull, built with React, WebGL and a cloth simulation.

Source: https://kokonutui.com/docs/backgrounds/drape-background

## Installation

```bash
npx shadcn@latest add @kokonutui/drape-background
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Drape Background
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface DrapeBackgroundProps {
  className?: string;
  /** Content shown over the curtain. Pass `null` for a bare background. */
  children?: ReactNode;
  /** Strength of the breeze. 0 lets the curtain hang still. */
  wind?: number;
  /** Depth of the pleats along the top, in px. */
  pleat?: number;
  /** Push the fabric with the cursor and grab it to drag it around. */
  interactive?: boolean;
}

// Simulation, in px and seconds, stepped at a fixed rate so it behaves the
// same at any refresh rate.
const STEP = 1 / 60;
const GRAVITY = 980;
const DAMPING = 0.986;
const ITERATIONS = 4;
// Roughly this many columns across the surface, never finer than MIN_CELL.
const COLUMNS = 46;
const MIN_CELL = 16;
// The top edge is gathered onto a rod: pins sit closer than the cloth
// between them, and the slack falls into folds.
const GATHER = 0.8;
const PLEAT_PERIOD = 4;
// How far the hand reaches into the cloth, and how hard it pushes.
const HAND_RADIUS = 120;
const HAND_PUSH = 7;
const HAND_DRAG = 2.4;
// Stiffness of the skip-one links that keep folds round instead of creased.
const BEND = 0.35;
// Perspective: distance from the eye to the screen plane, in px.
const FOCAL = 1400;
// Below this much movement per step, with no wind, the cloth is asleep.
const REST = 0.02;

interface Cloth {
  cols: number;
  rows: number;
  rest: number;
  pos: Float32Array;
  prev: Float32Array;
  pinned: Uint8Array;
  pins: Float32Array;
  links: Uint32Array;
  lengths: Float32Array;
  stiffness: Float32Array;
}

/**
 * Links between neighbours hold the weave; skip-one links give it a little
 * body, so it folds in curves instead of creasing.
 */
function createLinks(cols: number, rows: number, rest: number) {
  const links: number[] = [];
  const lengths: number[] = [];
  const stiffness: number[] = [];
  const link = (a: number, b: number, length: number, stiff: number) => {
    links.push(a, b);
    lengths.push(length);
    stiffness.push(stiff);
  };
  for (let j = 0; j < rows; j++) {
    for (let i = 0; i < cols; i++) {
      const a = j * cols + i;
      if (i + 1 < cols && j > 0) {
        link(a, a + 1, rest, 1);
      }
      if (j + 1 < rows) {
        link(a, a + cols, rest, 1);
      }
      if (i + 2 < cols && j > 0) {
        link(a, a + 2, rest * 2, BEND);
      }
      if (j + 2 < rows) {
        link(a, a + cols * 2, rest * 2, BEND);
      }
    }
  }
  return { links, lengths, stiffness };
}

function createCloth(width: number, height: number, pleat: number): Cloth {
  const rest = Math.max(MIN_CELL, (width * 1.16) / COLUMNS / GATHER);
  const spacing = rest * GATHER;
  const cols = Math.ceil((width * 1.16) / spacing) + 1;
  const rows = Math.ceil((height * 1.12) / rest) + 1;
  const left = (width - (cols - 1) * spacing) / 2;
  const top = -rest * 0.5;
  const count = cols * rows;
  const pos = new Float32Array(count * 3);
  const pinned = new Uint8Array(count);
  const pins = new Float32Array(cols * 3);

  // Folds a little uneven, as a hand-gathered curtain hangs.
  const folds = Array.from({ length: cols }, (_, i) => {
    let phase = 0;
    for (let c = 0; c < i; c++) {
      phase += ((Math.PI * 2) / PLEAT_PERIOD) * (1 + 0.3 * Math.sin(c * 0.9));
    }
    return pleat * Math.sin(phase) * (0.8 + 0.2 * Math.cos(i * 0.37));
  });
  for (let j = 0; j < rows; j++) {
    for (let i = 0; i < cols; i++) {
      const k = (j * cols + i) * 3;
      const z = folds[i];
      pos[k] = left + i * spacing;
      pos[k + 1] = top + j * rest;
      pos[k + 2] = z;
      if (j === 0) {
        pinned[i] = 1;
        pins.set([pos[k], pos[k + 1], z], i * 3);
      }
    }
  }

  const { links, lengths, stiffness } = createLinks(cols, rows, rest);

  return {
    cols,
    rows,
    rest,
    pos,
    prev: pos.slice(),
    pinned,
    pins,
    links: Uint32Array.from(links),
    lengths: Float32Array.from(lengths),
    stiffness: Float32Array.from(stiffness),
  };
}

interface Forces {
  time: number;
  wind: number;
  hand: { x: number; y: number; vx: number; vy: number; on: boolean };
  grab: { index: number; x: number; y: number } | null;
}

const accel: [number, number, number] = [0, 0, 0];

/** Gravity, the breeze and the hand, acting on a point at (x, y). */
function accelerate(x: number, y: number, forces: Forces) {
  const { time, wind, hand } = forces;
  accel[0] = 0;
  accel[1] = GRAVITY;
  accel[2] = 0;
  if (wind > 0) {
    // Gusts: slow sine waves that roll across the curtain and swell.
    const gust =
      Math.sin(x * 0.006 + time * 0.9) * 0.6 +
      Math.sin(x * 0.013 - time * 1.7 + y * 0.004) * 0.4;
    const swell = 0.6 + 0.4 * Math.sin(time * 0.35);
    accel[2] += gust * swell * wind * 260 * (y / 600);
    accel[0] += Math.sin(time * 0.5 + y * 0.003) * wind * 30;
  }
  if (hand.on) {
    const dx = x - hand.x;
    const dy = y - hand.y;
    const d2 = dx * dx + dy * dy;
    if (d2 < HAND_RADIUS * HAND_RADIUS) {
      const fall = 1 - Math.sqrt(d2) / HAND_RADIUS;
      const f = fall * fall;
      // Press the fabric back, and drag it a little along with the hand.
      accel[2] += f * HAND_PUSH * 1000;
      accel[0] += f * hand.vx * HAND_DRAG * 60;
      accel[1] += f * hand.vy * HAND_DRAG * 60;
    }
  }
  return accel;
}

/** Verlet step: move every free point under its forces. */
function integrate(cloth: Cloth, forces: Forces) {
  const { pos, prev, pinned } = cloth;
  const dt2 = STEP * STEP;
  let motion = 0;
  for (let n = 0; n < pinned.length; n++) {
    if (pinned[n]) {
      continue;
    }
    const k = n * 3;
    const x = pos[k];
    const y = pos[k + 1];
    const z = pos[k + 2];
    const [ax, ay, az] = accelerate(x, y, forces);
    const vx = (x - prev[k]) * DAMPING;
    const vy = (y - prev[k + 1]) * DAMPING;
    const vz = (z - prev[k + 2]) * DAMPING;
    prev[k] = x;
    prev[k + 1] = y;
    prev[k + 2] = z;
    pos[k] = x + vx + ax * dt2;
    pos[k + 1] = y + vy + ay * dt2;
    pos[k + 2] = z + vz + az * dt2;
    motion += Math.abs(vx) + Math.abs(vy) + Math.abs(vz);
  }
  return motion / pinned.length;
}

function relax(cloth: Cloth, grab: Forces["grab"]) {
  const { pos, pinned, links, lengths, stiffness, pins } = cloth;
  for (let it = 0; it < ITERATIONS; it++) {
    for (let l = 0; l < lengths.length; l++) {
      const a = links[l * 2];
      const b = links[l * 2 + 1];
      const ka = a * 3;
      const kb = b * 3;
      const dx = pos[kb] - pos[ka];
      const dy = pos[kb + 1] - pos[ka + 1];
      const dz = pos[kb + 2] - pos[ka + 2];
      const d = Math.sqrt(dx * dx + dy * dy + dz * dz) || 1;
      const diff = (d - lengths[l]) / d;
      // Bend links only resist being squeezed, so folds stay soft.
      if (stiffness[l] < 1 && diff > 0) {
        continue;
      }
      // Pinned points don't move; links between two pins aren't made.
      const wa = 1 - pinned[a];
      const wb = 1 - pinned[b];
      const s = (diff * stiffness[l]) / (wa + wb);
      pos[ka] += dx * s * wa;
      pos[ka + 1] += dy * s * wa;
      pos[ka + 2] += dz * s * wa;
      pos[kb] -= dx * s * wb;
      pos[kb + 1] -= dy * s * wb;
      pos[kb + 2] -= dz * s * wb;
    }
    if (grab) {
      const k = grab.index * 3;
      pos[k] = grab.x;
      pos[k + 1] = grab.y;
    }
    for (let i = 0; i < cloth.cols; i++) {
      pos.set(pins.subarray(i * 3, i * 3 + 3), i * 3);
    }
  }
}

/** Interleaved position and normal for every point, for the GPU. */
function writeVertices(cloth: Cloth, out: Float32Array) {
  const { cols, rows, pos } = cloth;
  for (let j = 0; j < rows; j++) {
    for (let i = 0; i < cols; i++) {
      const n = j * cols + i;
      const l = (j * cols + Math.max(i - 1, 0)) * 3;
      const r = (j * cols + Math.min(i + 1, cols - 1)) * 3;
      const u = (Math.max(j - 1, 0) * cols + i) * 3;
      const d = (Math.min(j + 1, rows - 1) * cols + i) * 3;
      const ax = pos[r] - pos[l];
      const ay = pos[r + 1] - pos[l + 1];
      const az = pos[r + 2] - pos[l + 2];
      const bx = pos[d] - pos[u];
      const by = pos[d + 1] - pos[u + 1];
      const bz = pos[d + 2] - pos[u + 2];
      // Down × across points out of the screen, towards the viewer.
      let nx = by * az - bz * ay;
      let ny = bz * ax - bx * az;
      let nz = bx * ay - by * ax;
      const len = Math.sqrt(nx * nx + ny * ny + nz * nz) || 1;
      nx /= len;
      ny /= len;
      nz /= len;
      const o = n * 6;
      out[o] = pos[n * 3];
      out[o + 1] = pos[n * 3 + 1];
      out[o + 2] = pos[n * 3 + 2];
      out[o + 3] = nx;
      out[o + 4] = ny;
      out[o + 5] = nz;
    }
  }
}

const VERTEX = `
attribute vec3 aPos;
attribute vec3 aNormal;
uniform vec2 uSize;
uniform float uFocal;
varying vec3 vNormal;
void main() {
  float s = uFocal / (uFocal + aPos.z);
  vec2 p = uSize * 0.5 + (aPos.xy - uSize * 0.5) * s;
  gl_Position = vec4(p.x / uSize.x * 2.0 - 1.0, 1.0 - p.y / uSize.y * 2.0, clamp(aPos.z / 4000.0, -1.0, 1.0), 1.0);
  vNormal = aNormal;
}`;

// Soft wrapped light from the top left and a satin sheen, blended between
// two theme colors so the curtain sits in the page in light and dark mode.
const FRAGMENT = `
precision mediump float;
uniform vec3 uLit;
uniform vec3 uShade;
varying vec3 vNormal;
void main() {
  vec3 n = normalize(vNormal);
  if (n.z > 0.0) n = -n;
  vec3 light = normalize(vec3(-0.45, -0.55, -0.7));
  float diffuse = max(dot(n, light), 0.0);
  float wrap = diffuse * 0.8 + 0.2;
  float sheen = pow(max(dot(reflect(-light, n), vec3(0.0, 0.0, -1.0)), 0.0), 18.0);
  float t = clamp(wrap * wrap + sheen * 0.15, 0.0, 1.0);
  gl_FragColor = vec4(mix(uShade, uLit, t), 1.0);
}`;

function compile(gl: WebGLRenderingContext, type: number, source: string) {
  const shader = gl.createShader(type);
  if (!shader) {
    return null;
  }
  gl.shaderSource(shader, source);
  gl.compileShader(shader);
  return shader;
}

function createRenderer(gl: WebGLRenderingContext) {
  const program = gl.createProgram();
  const vs = compile(gl, gl.VERTEX_SHADER, VERTEX);
  const fs = compile(gl, gl.FRAGMENT_SHADER, FRAGMENT);
  if (!(program && vs && fs)) {
    return null;
  }
  gl.attachShader(program, vs);
  gl.attachShader(program, fs);
  gl.linkProgram(program);
  if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
    return null;
  }
  // biome-ignore lint/correctness/useHookAtTopLevel: a WebGL call, not a React hook.
  gl.useProgram(program);
  const vertexBuffer = gl.createBuffer();
  const indexBuffer = gl.createBuffer();
  const aPos = gl.getAttribLocation(program, "aPos");
  const aNormal = gl.getAttribLocation(program, "aNormal");
  gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
  gl.enableVertexAttribArray(aPos);
  gl.enableVertexAttribArray(aNormal);
  gl.vertexAttribPointer(aPos, 3, gl.FLOAT, false, 24, 0);
  gl.vertexAttribPointer(aNormal, 3, gl.FLOAT, false, 24, 12);
  gl.enable(gl.DEPTH_TEST);
  gl.depthFunc(gl.LEQUAL);
  return {
    uSize: gl.getUniformLocation(program, "uSize"),
    uFocal: gl.getUniformLocation(program, "uFocal"),
    uLit: gl.getUniformLocation(program, "uLit"),
    uShade: gl.getUniformLocation(program, "uShade"),
    setMesh(cols: number, rows: number) {
      const indices = new Uint16Array((cols - 1) * (rows - 1) * 6);
      let o = 0;
      for (let j = 0; j < rows - 1; j++) {
        for (let i = 0; i < cols - 1; i++) {
          const a = j * cols + i;
          indices.set([a, a + 1, a + cols, a + 1, a + cols + 1, a + cols], o);
          o += 6;
        }
      }
      gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
      return indices.length;
    },
    destroy() {
      gl.deleteBuffer(vertexBuffer);
      gl.deleteBuffer(indexBuffer);
      gl.deleteProgram(program);
      gl.deleteShader(vs);
      gl.deleteShader(fs);
    },
  };
}

/** Any CSS color (oklch included) as 0-1 RGB, via a 1px canvas. */
function toRgb(color: string, probe: CanvasRenderingContext2D) {
  probe.clearRect(0, 0, 1, 1);
  probe.fillStyle = color;
  probe.fillRect(0, 0, 1, 1);
  const [r, g, b] = probe.getImageData(0, 0, 1, 1).data;
  return [r / 255, g / 255, b / 255] as const;
}

export default function DrapeBackground({
  className,
  children,
  wind = 1,
  pleat = 34,
  interactive = true,
}: DrapeBackgroundProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const litRef = useRef<HTMLSpanElement>(null);
  const shadeRef = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const gl = canvas?.getContext("webgl", { antialias: true });
    const probe = document
      .createElement("canvas")
      .getContext("2d", { willReadFrequently: true });
    if (!(root && canvas && gl && probe)) {
      return;
    }
    const renderer = createRenderer(gl);
    if (!renderer) {
      return;
    }

    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const forces: Forces = {
      time: 0,
      wind: reduceMotion ? 0 : wind,
      hand: { x: 0, y: 0, vx: 0, vy: 0, on: false },
      grab: null,
    };

    let width = 0;
    let height = 0;
    let cloth: Cloth | null = null;
    let vertices = new Float32Array(0);
    let indexCount = 0;
    let raf = 0;
    let last = 0;
    let carry = 0;
    let quiet = 0;
    let visible = true;
    let colorKey = "";

    const readColors = () => {
      const lit = getComputedStyle(litRef.current as Element).color;
      const shade = getComputedStyle(shadeRef.current as Element).color;
      if (`${lit}|${shade}` === colorKey) {
        return false;
      }
      colorKey = `${lit}|${shade}`;
      gl.uniform3fv(renderer.uLit, toRgb(lit, probe));
      gl.uniform3fv(renderer.uShade, toRgb(shade, probe));
      return true;
    };

    const draw = () => {
      if (!cloth) {
        return;
      }
      writeVertices(cloth, vertices);
      gl.bufferData(gl.ARRAY_BUFFER, vertices, gl.DYNAMIC_DRAW);
      // biome-ignore lint/suspicious/noBitwiseOperators: WebGL clear flags.
      gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
      gl.drawElements(gl.TRIANGLES, indexCount, gl.UNSIGNED_SHORT, 0);
    };

    const build = () => {
      const rect = canvas.getBoundingClientRect();
      const dpr = Math.min(window.devicePixelRatio || 1, 2);
      width = rect.width;
      height = rect.height;
      if (width < 2 || height < 2) {
        return;
      }
      canvas.width = Math.round(width * dpr);
      canvas.height = Math.round(height * dpr);
      gl.viewport(0, 0, canvas.width, canvas.height);
      gl.uniform2f(renderer.uSize, width, height);
      gl.uniform1f(renderer.uFocal, FOCAL);
      cloth = createCloth(width, height, pleat);
      vertices = new Float32Array(cloth.cols * cloth.rows * 6);
      indexCount = renderer.setMesh(cloth.cols, cloth.rows);
      // Let it fall and settle before the first frame, so it opens hanging.
      const settleForces = { ...forces, hand: { ...forces.hand, on: false } };
      for (let i = 0; i < 180; i++) {
        settleForces.time = forces.time + i * STEP;
        integrate(cloth, settleForces);
        relax(cloth, null);
      }
      draw();
    };

    const frame = (now: number) => {
      raf = 0;
      if (!(visible && cloth)) {
        return;
      }
      carry += last ? Math.min((now - last) / 1000, 0.1) : STEP;
      last = now;
      let moved = 0;
      let steps = 0;
      while (carry >= STEP && steps < 3) {
        forces.time += STEP;
        moved = integrate(cloth, forces);
        relax(cloth, forces.grab);
        carry -= STEP;
        steps++;
      }
      carry = Math.min(carry, STEP);
      forces.hand.vx *= 0.8;
      forces.hand.vy *= 0.8;
      draw();
      quiet = moved < REST ? quiet + 1 : 0;
      const awake =
        forces.wind > 0 || forces.hand.on || forces.grab || quiet < 30;
      if (awake) {
        raf = requestAnimationFrame(frame);
      }
    };

    const start = () => {
      if (!raf && visible && !reduceMotion) {
        last = 0;
        quiet = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    readColors();
    gl.clearColor(0, 0, 0, 0);
    build();
    canvas.style.opacity = "1";
    start();

    const resizeObserver = new ResizeObserver(() => {
      build();
      start();
    });
    resizeObserver.observe(canvas);

    const intersection = new IntersectionObserver(([entry]) => {
      visible = entry.isIntersecting && document.visibilityState === "visible";
      start();
    });
    intersection.observe(root);
    const onVisibility = () => {
      visible = document.visibilityState === "visible";
      start();
    };
    document.addEventListener("visibilitychange", onVisibility);

    // Follow light and dark mode without asking the app for a theme.
    const colorTimer = window.setInterval(() => {
      if (readColors() && !raf) {
        draw();
      }
    }, 500);

    const local = (event: PointerEvent) => {
      const rect = canvas.getBoundingClientRect();
      return { x: event.clientX - rect.left, y: event.clientY - rect.top };
    };

    /** The point drawn nearest the pointer, within reach. */
    const nearest = (x: number, y: number) => {
      if (!cloth) {
        return -1;
      }
      let best = -1;
      let bestD = 70 * 70;
      for (let n = cloth.cols; n < cloth.pinned.length; n++) {
        const k = n * 3;
        const s = FOCAL / (FOCAL + cloth.pos[k + 2]);
        const px = width / 2 + (cloth.pos[k] - width / 2) * s;
        const py = height / 2 + (cloth.pos[k + 1] - height / 2) * s;
        const d = (px - x) ** 2 + (py - y) ** 2;
        if (d < bestD) {
          bestD = d;
          best = n;
        }
      }
      return best;
    };

    const onMove = (event: PointerEvent) => {
      const p = local(event);
      const hand = forces.hand;
      if (forces.grab) {
        forces.grab.x = p.x;
        forces.grab.y = p.y;
      } else if (event.pointerType === "mouse") {
        if (hand.on) {
          hand.vx = hand.vx * 0.5 + (p.x - hand.x) * 0.5;
          hand.vy = hand.vy * 0.5 + (p.y - hand.y) * 0.5;
        }
        hand.on = true;
      }
      hand.x = p.x;
      hand.y = p.y;
      start();
    };
    const onLeave = () => {
      forces.hand.on = false;
    };
    const onDown = (event: PointerEvent) => {
      // Clicks on the content (links, buttons) are not meant for the cloth.
      if ((event.target as HTMLElement).closest("a, button, input, textarea")) {
        return;
      }
      const p = local(event);
      const index = nearest(p.x, p.y);
      if (index < 0) {
        return;
      }
      event.preventDefault();
      root.setPointerCapture(event.pointerId);
      forces.grab = { index, ...p };
      forces.hand.on = false;
      root.dataset.grabbing = "";
      start();
    };
    const onUp = () => {
      forces.grab = null;
      delete root.dataset.grabbing;
    };
    if (interactive && !reduceMotion) {
      root.addEventListener("pointermove", onMove);
      root.addEventListener("pointerleave", onLeave);
      root.addEventListener("pointerdown", onDown);
      root.addEventListener("pointerup", onUp);
      root.addEventListener("pointercancel", onUp);
    }

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      window.clearInterval(colorTimer);
      root.removeEventListener("pointermove", onMove);
      root.removeEventListener("pointerleave", onLeave);
      root.removeEventListener("pointerdown", onDown);
      root.removeEventListener("pointerup", onUp);
      root.removeEventListener("pointercancel", onUp);
      renderer.destroy();
    };
  }, [wind, pleat, interactive]);

  return (
    <div
      className={cn(
        "relative flex min-h-[560px] w-full touch-pan-y items-center justify-center overflow-hidden bg-zinc-100 text-zinc-900 data-[grabbing]:cursor-grabbing dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={rootRef}
    >
      {/* Theme colors for the shader: the lit face and the deepest fold. */}
      <span className="hidden text-white dark:text-zinc-800" ref={litRef} />
      <span className="hidden text-zinc-300 dark:text-black" ref={shadeRef} />
      <div aria-hidden="true" className="pointer-events-none absolute inset-0">
        <canvas
          className="h-full w-full opacity-0 transition-opacity duration-700 ease-out"
          ref={canvasRef}
        />
      </div>
      {children === undefined ? <DefaultContent /> : children}
    </div>
  );
}

function DefaultContent() {
  return (
    <div className="pointer-events-none relative flex max-w-xl flex-col items-center gap-4 px-6 text-center">
      <h1 className="font-semibold text-4xl tracking-tight sm:text-5xl">
        Behind the curtain
      </h1>
      <p className="max-w-sm text-base text-zinc-500 dark:text-zinc-400">
        A pleated curtain in a light breeze. Sweep the cursor through it, or
        grab a fold and pull.
      </p>
    </div>
  );
}
```


---

# Wind
> Streamlines that part around the cursor, swirl in its wake and scatter on click, built with React and Canvas.

Source: https://kokonutui.com/docs/backgrounds/flow-field

## Installation

```bash
npx shadcn@latest add @kokonutui/flow-field
```

## Source

```tsx
// biome-ignore-all lint/suspicious/noBitwiseOperators: the noise hash is bit arithmetic.
"use client";

/**
 * @author: @dorianbaffier
 * @description: Wind. Streamlines that part around the cursor, swirl in its wake and scatter on click.
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface FlowFieldProps {
  className?: string;
  /** Content drawn over the wind, such as a hero's heading. */
  children?: ReactNode;
  /** Multiplies the number of particles (about 700 at 1). */
  density?: number;
  /** How fast the wind blows. 0 holds a still frame. */
  speed?: number;
  /** The cursor parts the streams and stirs a wake; a click sends a gust. */
  interactive?: boolean;
}

// Particles at density 1. Narrow screens get fewer.
const BASE_COUNT = 700;
// Wind speed in px/s at speed 1, and the size of its bends (px).
const WIND = 64;
const NOISE_SCALE = 340;
// How far the wind may turn from left-to-right, in radians.
const TURN = 1.15;
// How quickly a particle takes up the local wind (per second). Lower values
// give them more momentum.
const RESPONSE = 9;
// Trails fade with this time constant (seconds).
const TRAIL_TAU = 0.22;
// The cursor is a disc of this radius (px) that the air flows around.
const DISC_RADIUS = 64;
const DISC_FOLLOW = 18;
const DISC_RISE = 7;
// Moving faster than this (px/s) sheds vortices behind the disc.
const SHED_SPEED = 150;
const SHED_MS = 42;
const MAX_VORTICES = 30;
// Each shed vortex: core radius (px), strength per px/s of cursor speed,
// how fast it weakens (s) and how fast its core spreads (s).
const VORTEX_CORE = 30;
const VORTEX_GAIN = 0.62 * Math.PI * 2 * VORTEX_CORE * 0.5;
const VORTEX_TAU = 1.1;
const VORTEX_SPREAD = 0.5;
const MAX_CURSOR_SPEED = 1600;
// A click sends a ring of wind outwards.
const GUST_MS = 1300;
const GUST_SPEED = 0.62; // px per ms
const GUST_WIDTH = 64;
const GUST_STRENGTH = 560; // px/s at the crest
// Four alpha levels: each is one stroked path, so a frame is four draw calls.
const BUCKETS = [0.18, 0.34, 0.54, 0.8] as const;
// Segments longer than this are a wrap or a push, not motion.
const MAX_SEGMENT = 40;
// The drift alone is slow; half the frame rate looks the same and costs
// half as much. Anything following the hand gets every frame.
const IDLE_FRAME_MS = 33;
// Destination-out can't fade the last few alpha levels in small steps, so
// while frames are short a stronger pass clears that residue once a second.
const CLEANUP_MS = 1000;
const CLEANUP_ALPHA = 0.24;
// The still frame used for reduced motion and speed 0.
const STILL_LINES = 340;
const STILL_STEPS = 18;
const STILL_DT = 0.05;

/** Seeded 3D gradient noise (Ken Perlin's improved noise), about -1 to 1. */
function createNoise(seed: number) {
  const p = Array.from({ length: 256 }, (_, i) => i);
  let state = seed >>> 0 || 1;
  const random = () => {
    state = (state * 1_664_525 + 1_013_904_223) >>> 0;
    return state / 4_294_967_296;
  };
  for (let i = 255; i > 0; i--) {
    const j = Math.floor(random() * (i + 1));
    [p[i], p[j]] = [p[j], p[i]];
  }
  const perm = new Uint8Array(512);
  for (let i = 0; i < 512; i++) {
    perm[i] = p[i & 255];
  }
  const fade = (t: number) => t * t * t * (t * (t * 6 - 15) + 10);
  const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
  const grad = (hash: number, x: number, y: number, z: number) => {
    const h = hash & 15;
    const u = h < 8 ? x : y;
    let v = z;
    if (h < 4) {
      v = y;
    } else if (h === 12 || h === 14) {
      v = x;
    }
    return ((h & 1) === 0 ? u : -u) + ((h & 2) === 0 ? v : -v);
  };

  return (x: number, y: number, z: number) => {
    const X = Math.floor(x) & 255;
    const Y = Math.floor(y) & 255;
    const Z = Math.floor(z) & 255;
    const fx = x - Math.floor(x);
    const fy = y - Math.floor(y);
    const fz = z - Math.floor(z);
    const u = fade(fx);
    const v = fade(fy);
    const w = fade(fz);
    const A = perm[X] + Y;
    const AA = perm[A] + Z;
    const AB = perm[A + 1] + Z;
    const B = perm[X + 1] + Y;
    const BA = perm[B] + Z;
    const BB = perm[B + 1] + Z;
    return lerp(
      lerp(
        lerp(grad(perm[AA], fx, fy, fz), grad(perm[BA], fx - 1, fy, fz), u),
        lerp(
          grad(perm[AB], fx, fy - 1, fz),
          grad(perm[BB], fx - 1, fy - 1, fz),
          u
        ),
        v
      ),
      lerp(
        lerp(
          grad(perm[AA + 1], fx, fy, fz - 1),
          grad(perm[BA + 1], fx - 1, fy, fz - 1),
          u
        ),
        lerp(
          grad(perm[AB + 1], fx, fy - 1, fz - 1),
          grad(perm[BB + 1], fx - 1, fy - 1, fz - 1),
          u
        ),
        v
      ),
      w
    );
  };
}

type Noise = ReturnType<typeof createNoise>;

/** The cursor, as a solid disc the air has to go around. */
interface Disc {
  x: number;
  y: number;
  targetX: number;
  targetY: number;
  vx: number;
  vy: number;
  /** 0 to 1: grows when the cursor arrives, shrinks when it leaves. */
  amount: number;
  on: boolean;
  lastShed: number;
  side: number;
}

/** A Lamb-Oseen vortex shed by the moving disc. */
interface Vortex {
  x: number;
  y: number;
  gamma: number;
  age: number;
}

interface Gust {
  x: number;
  y: number;
  start: number;
}

interface Air {
  noise: Noise;
  time: number;
  wind: number;
  disc: Disc;
  vortices: Vortex[];
  gusts: Gust[];
  now: number;
}

// Scratch vector the field functions write into, so a frame allocates
// nothing per particle.
const out = { x: 0, y: 0 };

/** The undisturbed wind: left to right, turned by slowly drifting noise. */
function baseWind(air: Air, x: number, y: number) {
  const t = air.time;
  const angle =
    air.noise((x - t * WIND * 0.6) / NOISE_SCALE, y / NOISE_SCALE, t * 0.06) *
    TURN;
  out.x = Math.cos(angle) * air.wind;
  out.y = Math.sin(angle) * air.wind;
}

/**
 * Potential flow around a disc: the local wind (relative to the moving disc)
 * plus a doublet, so streams split ahead of it, speed up round its sides and
 * close up behind. In complex form, u - iv = conj(w) - (w - V) R^2 / z^2.
 */
function addDisc(disc: Disc, x: number, y: number) {
  const radius = DISC_RADIUS * disc.amount;
  const dx = x - disc.x;
  const dy = y - disc.y;
  const r2 = Math.max(dx * dx + dy * dy, radius * radius);
  const k = (radius * radius) / (r2 * r2);
  const rx = out.x - disc.vx;
  const ry = out.y - disc.vy;
  const p = dx * dx - dy * dy;
  const q = -2 * dx * dy;
  out.x -= k * (rx * p - ry * q);
  out.y += k * (rx * q + ry * p);
}

function addVortices(vortices: Vortex[], x: number, y: number) {
  for (const v of vortices) {
    const dx = x - v.x;
    const dy = y - v.y;
    const r2 = dx * dx + dy * dy + 1;
    const core = VORTEX_CORE * VORTEX_CORE * (1 + v.age / VORTEX_SPREAD);
    const swirl =
      ((v.gamma * Math.exp(-v.age / VORTEX_TAU)) / (2 * Math.PI * r2)) *
      (1 - Math.exp(-r2 / core));
    out.x -= swirl * dy;
    out.y += swirl * dx;
  }
}

function addGusts(gusts: Gust[], now: number, x: number, y: number) {
  for (const g of gusts) {
    const age = now - g.start;
    const dx = x - g.x;
    const dy = y - g.y;
    const r = Math.hypot(dx, dy) + 0.001;
    const d = r - age * GUST_SPEED;
    const fadeOut = 1 - age / GUST_MS;
    const push =
      GUST_STRENGTH *
      fadeOut *
      fadeOut *
      Math.exp(-(d * d) / (2 * GUST_WIDTH * GUST_WIDTH));
    out.x += (push * dx) / r;
    out.y += (push * dy) / r;
  }
}

/** The air's velocity at one point, written into `out`. */
function velocityAt(air: Air, x: number, y: number) {
  baseWind(air, x, y);
  if (air.disc.amount > 0.002) {
    addDisc(air.disc, x, y);
  }
  if (air.vortices.length > 0) {
    addVortices(air.vortices, x, y);
  }
  if (air.gusts.length > 0) {
    addGusts(air.gusts, air.now, x, y);
  }
}

/** Glide the disc after the cursor and shed vortices off its sides. */
function stepDisc(disc: Disc, vortices: Vortex[], dt: number, now: number) {
  const px = disc.x;
  const py = disc.y;
  const follow = 1 - Math.exp(-DISC_FOLLOW * dt);
  disc.x += (disc.targetX - disc.x) * follow;
  disc.y += (disc.targetY - disc.y) * follow;
  const goal = disc.on ? 1 : 0;
  disc.amount += (goal - disc.amount) * (1 - Math.exp(-DISC_RISE * dt));
  if (disc.amount < 0.002 && !disc.on) {
    disc.amount = 0;
  }
  const smooth = 1 - Math.exp(-14 * dt);
  disc.vx += ((disc.x - px) / dt - disc.vx) * smooth;
  disc.vy += ((disc.y - py) / dt - disc.vy) * smooth;

  const speed = Math.hypot(disc.vx, disc.vy);
  if (
    speed < SHED_SPEED ||
    disc.amount < 0.5 ||
    now - disc.lastShed < SHED_MS
  ) {
    return;
  }
  disc.lastShed = now;
  disc.side = -disc.side;
  const ux = disc.vx / speed;
  const uy = disc.vy / speed;
  const radius = DISC_RADIUS * disc.amount;
  // Alternate sides, like the vortex street behind a cylinder. The air
  // dragged along the disc's flank sets which way each one spins.
  vortices.push({
    x: disc.x - ux * radius * 0.9 - uy * disc.side * radius * 0.55,
    y: disc.y - uy * radius * 0.9 + ux * disc.side * radius * 0.55,
    gamma: disc.side * VORTEX_GAIN * Math.min(speed, MAX_CURSOR_SPEED),
    age: 0,
  });
  if (vortices.length > MAX_VORTICES) {
    vortices.shift();
  }
}

/** Age the wake: vortices drift downwind and weaken until they're gone. */
function stepWake(air: Air, dt: number) {
  for (const v of air.vortices) {
    baseWind(air, v.x, v.y);
    v.x += out.x * 0.85 * dt;
    v.y += out.y * 0.85 * dt;
    v.age += dt;
  }
  while (air.vortices.length > 0 && air.vortices[0].age > VORTEX_TAU * 3.5) {
    air.vortices.shift();
  }
  while (air.gusts.length > 0 && air.now - air.gusts[0].start > GUST_MS) {
    air.gusts.shift();
  }
}

/** Particle state as flat arrays: cheap to walk 700 times a frame. */
class Particles {
  count = 0;
  width = 0;
  height = 0;
  x = new Float32Array(0);
  y = new Float32Array(0);
  vx = new Float32Array(0);
  vy = new Float32Array(0);
  life = new Float32Array(0);
  maxLife = new Float32Array(0);
  pace = new Float32Array(0);

  resize(count: number, width: number, height: number) {
    if (count === this.count) {
      // Same count, new size: stretch the particles over the new area so a
      // wider canvas doesn't start with an empty strip.
      const sx = this.width > 0 ? width / this.width : 1;
      const sy = this.height > 0 ? height / this.height : 1;
      for (let i = 0; i < count; i++) {
        this.x[i] *= sx;
        this.y[i] *= sy;
      }
      this.width = width;
      this.height = height;
      return;
    }
    this.width = width;
    this.height = height;
    this.count = count;
    this.x = new Float32Array(count);
    this.y = new Float32Array(count);
    this.vx = new Float32Array(count);
    this.vy = new Float32Array(count);
    this.life = new Float32Array(count);
    this.maxLife = new Float32Array(count);
    this.pace = new Float32Array(count);
    for (let i = 0; i < count; i++) {
      this.spawn(i, width, height);
      // Start part way through their lives so they don't all fade together.
      this.life[i] = Math.random() * this.maxLife[i];
    }
  }

  spawn(i: number, width: number, height: number) {
    this.x[i] = Math.random() * width;
    this.y[i] = Math.random() * height;
    this.vx[i] = 0;
    this.vy[i] = 0;
    this.life[i] = 0;
    this.maxLife[i] = 3 + Math.random() * 5;
    this.pace[i] = 0.75 + Math.random() * 0.5;
  }
}

/** Fade in at birth and out before respawning, so nothing pops. */
function envelope(life: number, maxLife: number) {
  return Math.min(1, life / 0.6, (maxLife - life) / 0.6);
}

function bucketOf(intensity: number) {
  return Math.max(0, Math.min(BUCKETS.length - 1, Math.floor(intensity * 4)));
}

/** Wrap a particle that blew off one edge back in on the opposite one. */
function wrap(v: number, size: number) {
  if (v < -8) {
    return v + size + 16;
  }
  if (v > size + 8) {
    return v - size - 16;
  }
  return v;
}

interface StepContext {
  air: Air;
  particles: Particles;
  paths: Path2D[];
  width: number;
  height: number;
  dt: number;
}

/** Push a particle the disc swept over back out to its surface. */
function keepOutOfDisc(p: Particles, i: number, disc: Disc) {
  if (disc.amount === 0) {
    return;
  }
  const radius = DISC_RADIUS * disc.amount;
  const dx = p.x[i] - disc.x;
  const dy = p.y[i] - disc.y;
  const r2 = dx * dx + dy * dy;
  if (r2 >= radius * radius || r2 < 0.0001) {
    return;
  }
  const r = Math.sqrt(r2);
  p.x[i] = disc.x + (dx / r) * radius;
  p.y[i] = disc.y + (dy / r) * radius;
}

function stepParticle(c: StepContext, i: number) {
  const { air, particles: p, dt } = c;
  p.life[i] += dt;
  if (p.life[i] > p.maxLife[i]) {
    p.spawn(i, c.width, c.height);
    return;
  }
  const x0 = p.x[i];
  const y0 = p.y[i];
  velocityAt(air, x0, y0);
  const take = 1 - Math.exp(-RESPONSE * dt);
  p.vx[i] += (out.x * p.pace[i] - p.vx[i]) * take;
  p.vy[i] += (out.y * p.pace[i] - p.vy[i]) * take;
  p.x[i] = wrap(x0 + p.vx[i] * dt, c.width);
  p.y[i] = wrap(y0 + p.vy[i] * dt, c.height);
  keepOutOfDisc(p, i, air.disc);

  const sx = p.x[i] - x0;
  const sy = p.y[i] - y0;
  if (sx * sx + sy * sy > MAX_SEGMENT * MAX_SEGMENT) {
    return;
  }
  // Faster air draws darker, so the wake and the flanks of the disc stand
  // out against the drift.
  const pace = Math.hypot(p.vx[i], p.vy[i]) / (air.wind * 2.4 + 1);
  const intensity = envelope(p.life[i], p.maxLife[i]) * Math.min(1, 0.4 + pace);
  const path = c.paths[bucketOf(intensity)];
  path.moveTo(x0, y0);
  path.lineTo(p.x[i], p.y[i]);
}

function strokeBuckets(ctx: CanvasRenderingContext2D, paths: Path2D[]) {
  for (let b = 0; b < BUCKETS.length; b++) {
    ctx.globalAlpha = BUCKETS[b];
    ctx.stroke(paths[b]);
  }
  ctx.globalAlpha = 1;
}

/** Streamlines traced from random seeds: a still picture of the wind. */
function drawStill(
  ctx: CanvasRenderingContext2D,
  air: Air,
  size: { width: number; height: number },
  lines: number
) {
  const paths = BUCKETS.map(() => new Path2D());
  for (let n = 0; n < lines; n++) {
    let x = Math.random() * size.width;
    let y = Math.random() * size.height;
    for (let s = 0; s < STILL_STEPS; s++) {
      baseWind(air, x, y);
      const nx = x + out.x * STILL_DT;
      const ny = y + out.y * STILL_DT;
      // Each line darkens towards its head, like a trail.
      const path = paths[bucketOf((s / STILL_STEPS) * 0.75)];
      path.moveTo(x, y);
      path.lineTo(nx, ny);
      x = nx;
      y = ny;
    }
  }
  strokeBuckets(ctx, paths);
}

function createAir(speed: number): Air {
  return {
    noise: createNoise(7),
    time: 0,
    // A still frame (speed 0) is still traced with the default wind.
    wind: WIND * (speed > 0 ? speed : 1),
    disc: {
      x: 0,
      y: 0,
      targetX: 0,
      targetY: 0,
      vx: 0,
      vy: 0,
      amount: 0,
      on: false,
      lastShed: 0,
      side: 1,
    },
    vortices: [],
    gusts: [],
    now: 0,
  };
}

/** Pointer events (on the window) mapped onto the disc and gusts. */
function bindPointer(
  root: HTMLElement,
  air: Air,
  wake: () => void,
  isVisible: () => boolean
) {
  const local = (event: PointerEvent) => {
    const rect = root.getBoundingClientRect();
    const x = event.clientX - rect.left;
    const y = event.clientY - rect.top;
    const inside = x >= 0 && y >= 0 && x <= rect.width && y <= rect.height;
    return { x, y, inside };
  };
  const onLeave = () => {
    air.disc.on = false;
  };
  const onMove = (event: PointerEvent) => {
    // A finger only stirs the air while it's down.
    if (
      !isVisible() ||
      (event.pointerType === "touch" && event.buttons === 0)
    ) {
      return;
    }
    const point = local(event);
    const disc = air.disc;
    if (!point.inside) {
      disc.on = false;
      return;
    }
    if (disc.amount < 0.05) {
      // Appear where the cursor came in rather than sliding over from the
      // last place it left.
      disc.x = point.x;
      disc.y = point.y;
      disc.vx = 0;
      disc.vy = 0;
    }
    disc.targetX = point.x;
    disc.targetY = point.y;
    disc.on = true;
    wake();
  };
  const onOut = (event: PointerEvent) => {
    if (!event.relatedTarget) {
      onLeave();
    }
  };
  const onUp = (event: PointerEvent) => {
    if (event.pointerType === "touch") {
      onLeave();
    }
  };
  const onDown = (event: PointerEvent) => {
    if (!isVisible() || event.button !== 0) {
      return;
    }
    // Clicks on the content (links, buttons, fields) are not gusts.
    const target = event.target instanceof Element ? event.target : null;
    if (
      target?.closest(
        "a, button, input, textarea, select, label, [role='button']"
      )
    ) {
      return;
    }
    const point = local(event);
    if (!point.inside) {
      return;
    }
    air.gusts.push({ x: point.x, y: point.y, start: performance.now() });
    if (air.gusts.length > 4) {
      air.gusts.shift();
    }
    onMove(event);
    wake();
  };

  const options = { passive: true };
  window.addEventListener("pointermove", onMove, options);
  window.addEventListener("pointerdown", onDown, options);
  window.addEventListener("pointerup", onUp, options);
  window.addEventListener("pointercancel", onLeave, options);
  document.addEventListener("pointerout", onOut, options);
  window.addEventListener("blur", onLeave);
  return () => {
    window.removeEventListener("pointermove", onMove);
    window.removeEventListener("pointerdown", onDown);
    window.removeEventListener("pointerup", onUp);
    window.removeEventListener("pointercancel", onLeave);
    document.removeEventListener("pointerout", onOut);
    window.removeEventListener("blur", onLeave);
  };
}

export default function FlowField({
  className,
  children,
  density = 1,
  speed = 1,
  interactive = true,
}: FlowFieldProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const ctx = canvas?.getContext("2d");
    if (!(root && canvas && ctx)) {
      return;
    }

    const still =
      speed <= 0 ||
      window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const air = createAir(speed);
    const particles = new Particles();
    const size = { width: 0, height: 0 };
    let color = "";
    let raf = 0;
    let lastStep = 0;
    let lastCleanup = 0;
    let visible = true;

    const countFor = (w: number) =>
      Math.round(BASE_COUNT * Math.max(density, 0) * (w < 520 ? 0.6 : 1));

    const paintStill = () => {
      ctx.clearRect(0, 0, size.width, size.height);
      ctx.strokeStyle = color;
      const lines = (countFor(size.width) * STILL_LINES) / BASE_COUNT;
      drawStill(ctx, air, size, Math.round(lines));
    };

    const resize = () => {
      const rect = canvas.getBoundingClientRect();
      const dpr = Math.min(window.devicePixelRatio || 1, 2);
      size.width = rect.width;
      size.height = rect.height;
      canvas.width = Math.round(size.width * dpr);
      canvas.height = Math.round(size.height * dpr);
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      ctx.lineCap = "butt";
      ctx.lineWidth = 1.2;
      color = getComputedStyle(canvas).color;
      particles.resize(countFor(size.width), size.width, size.height);
      if (still) {
        paintStill();
      }
    };

    const isActive = () =>
      air.disc.on ||
      air.disc.amount > 0 ||
      air.vortices.length > 0 ||
      air.gusts.length > 0;

    // Trails fade by erasing a little alpha each frame, so the canvas stays
    // transparent over whatever background sits behind it.
    const fade = (dt: number, now: number) => {
      ctx.globalCompositeOperation = "destination-out";
      ctx.fillStyle = "#000";
      ctx.globalAlpha = 1 - Math.exp(-dt / TRAIL_TAU);
      ctx.fillRect(0, 0, size.width, size.height);
      if (dt < 0.025 && now - lastCleanup > CLEANUP_MS) {
        lastCleanup = now;
        ctx.globalAlpha = CLEANUP_ALPHA;
        ctx.fillRect(0, 0, size.width, size.height);
      }
      ctx.globalAlpha = 1;
      ctx.globalCompositeOperation = "source-over";
    };

    const frame = (now: number) => {
      raf = 0;
      if (!visible) {
        return;
      }
      raf = requestAnimationFrame(frame);
      if (!isActive() && now - lastStep < IDLE_FRAME_MS - 4) {
        return;
      }
      const dt = lastStep ? Math.min((now - lastStep) / 1000, 0.05) : 1 / 60;
      lastStep = now;
      air.now = now;
      air.time += dt * speed;
      stepDisc(air.disc, air.vortices, dt, now);
      stepWake(air, dt);

      fade(dt, now);
      const paths = BUCKETS.map(() => new Path2D());
      const step: StepContext = {
        air,
        particles,
        paths,
        width: size.width,
        height: size.height,
        dt,
      };
      for (let i = 0; i < particles.count; i++) {
        stepParticle(step, i);
      }
      ctx.strokeStyle = color;
      strokeBuckets(ctx, paths);
    };

    const start = () => {
      if (!raf && visible && !still) {
        lastStep = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    resize();
    canvas.style.opacity = "1";
    start();

    const resizeObserver = new ResizeObserver(resize);
    resizeObserver.observe(canvas);

    // Moving the window to a screen with another pixel ratio doesn't resize
    // the canvas, so watch the ratio too or the trails go soft.
    let dprQuery: MediaQueryList | null = null;
    const watchDpr = () => {
      dprQuery?.removeEventListener("change", onDpr);
      dprQuery = window.matchMedia(
        `(resolution: ${window.devicePixelRatio}dppx)`
      );
      dprQuery.addEventListener("change", onDpr);
    };
    const onDpr = () => {
      resize();
      watchDpr();
    };
    watchDpr();

    // Stop drawing entirely while the wind is scrolled away or the tab is
    // in the background.
    let onScreen = true;
    const update = () => {
      visible = onScreen && document.visibilityState === "visible";
      start();
    };
    const intersection = new IntersectionObserver(([entry]) => {
      onScreen = entry.isIntersecting;
      update();
    });
    intersection.observe(root);
    document.addEventListener("visibilitychange", update);

    // Follow light and dark mode without asking the app for a theme. Only
    // checked while the wind is on screen.
    const colorTimer = window.setInterval(() => {
      if (!visible) {
        return;
      }
      const next = getComputedStyle(canvas).color;
      if (next !== color) {
        color = next;
        if (still) {
          paintStill();
        }
      }
    }, 500);

    // Listened for on the window, so content layered on top (a heading, a
    // button) still has the wind flowing round the cursor beneath it.
    const unbind =
      interactive && !still
        ? bindPointer(root, air, start, () => visible)
        : undefined;

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      dprQuery?.removeEventListener("change", onDpr);
      intersection.disconnect();
      document.removeEventListener("visibilitychange", update);
      window.clearInterval(colorTimer);
      unbind?.();
    };
  }, [density, speed, interactive]);

  return (
    <div
      className={cn(
        "pointer-events-none absolute inset-0 overflow-hidden",
        className
      )}
      ref={rootRef}
    >
      <div aria-hidden="true" className="absolute inset-0">
        <canvas
          className="h-full w-full opacity-0 transition-opacity duration-700 ease-out"
          ref={canvasRef}
        />
      </div>
      {children === undefined || children === null ? null : (
        <div className="pointer-events-auto relative h-full w-full">
          {children}
        </div>
      )}
    </div>
  );
}
```


---

# Halftone Background
> Any image, or a lit sphere, printed as a halftone dot screen, with a loupe that looks closer under the cursor, built with React and canvas.

Source: https://kokonutui.com/docs/backgrounds/halftone-background

## Installation

```bash
npx shadcn@latest add @kokonutui/halftone-background
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Halftone Background
 * @version: 1.0.0
 * @date: 2026-10-15
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface HalftoneBackgroundProps {
  className?: string;
  /** Content shown over the dots. Pass `null` for a bare background. */
  children?: ReactNode;
  /**
   * An image to print as dots. It must be same-origin or served with CORS
   * headers. Without one, a lit sphere is drawn.
   */
  src?: string;
  /** Distance between dots, in px. */
  cell?: number;
  /** Screen angle in degrees; 45 is the classic print angle. */
  angle?: number;
  /** Show a loupe under the cursor that prints at twice the resolution. */
  loupe?: boolean;
}

// The loupe's radius in px, and how much finer its screen is.
const LOUPE = 110;
const LOUPE_DETAIL = 2.2;
// The loupe trails the cursor with this time constant, in seconds.
const LOUPE_LAG = 0.08;
// Paper texture: the faintest tone printed everywhere.
const PAPER = 0.025;
const INTRO_MS = 900;

/** How much ink (0 to 1) a point takes, in px. */
type Field = (x: number, y: number) => number;

/**
 * A sphere lit from the upper left, with a soft shadow on the ground. With
 * `light` ink (a dark page) the lit side is printed instead of the shade.
 */
function sphereField(width: number, height: number, light: boolean): Field {
  // Matches the @3xl breakpoint: beside the copy when wide, above it when not.
  const wide = width >= 768;
  const r = wide
    ? Math.min(width, height) * 0.34
    : Math.min(width * 0.34, height * 0.2);
  const cx = wide ? width * 0.7 : width * 0.54;
  const cy = height * (wide ? 0.48 : 0.27);
  const sun = { x: -0.55, y: -0.6, z: 0.58 };
  const shadow = {
    x: cx + r * 0.35,
    y: cy + r * 1.02,
    rx: r * 1.15,
    ry: r * 0.24,
  };
  return (x, y) => {
    const nx = (x - cx) / r;
    const ny = (y - cy) / r;
    const d2 = nx * nx + ny * ny;
    if (d2 < 1) {
      const nz = Math.sqrt(1 - d2);
      const lambert = Math.max(nx * sun.x + ny * sun.y + nz * sun.z, 0);
      const brightness = 0.12 + 0.88 * lambert;
      return Math.max(light ? brightness : 1 - brightness, PAPER);
    }
    if (light) {
      return PAPER;
    }
    const sx = (x - shadow.x) / shadow.rx;
    const sy = (y - shadow.y) / shadow.ry;
    const s = 1 - Math.sqrt(sx * sx + sy * sy);
    return s > 0 ? Math.max(PAPER, 0.55 * s * s) : PAPER;
  };
}

/**
 * An image drawn to cover the box, sampled for its darkness, or for its
 * brightness when printing light ink on a dark page.
 */
function imageField(
  image: HTMLImageElement,
  width: number,
  height: number,
  light: boolean
): Field | null {
  const scale = 0.5;
  const w = Math.max(1, Math.round(width * scale));
  const h = Math.max(1, Math.round(height * scale));
  const ctx = document
    .createElement("canvas")
    .getContext("2d", { willReadFrequently: true });
  if (!ctx) {
    return null;
  }
  ctx.canvas.width = w;
  ctx.canvas.height = h;
  const fit = Math.max(w / image.naturalWidth, h / image.naturalHeight);
  const dw = image.naturalWidth * fit;
  const dh = image.naturalHeight * fit;
  ctx.drawImage(image, (w - dw) / 2, (h - dh) / 2, dw, dh);
  let data: Uint8ClampedArray;
  try {
    data = ctx.getImageData(0, 0, w, h).data;
  } catch {
    // A cross-origin image without CORS can't be read.
    return null;
  }
  return (x, y) => {
    const i = Math.min(Math.max(Math.round(x * scale), 0), w - 1);
    const j = Math.min(Math.max(Math.round(y * scale), 0), h - 1);
    const k = (j * w + i) * 4;
    const lum =
      (0.2126 * data[k] + 0.7152 * data[k + 1] + 0.0722 * data[k + 2]) / 255;
    return Math.max(light ? lum : 1 - lum, PAPER);
  };
}

/**
 * Add a rotated grid of dots to the current path, sized by `field`.
 * `grow` scales each dot (0 to 1) for the intro.
 */
function screen(
  ctx: CanvasRenderingContext2D,
  field: Field,
  options: {
    width: number;
    height: number;
    cell: number;
    angle: number;
    grow?: (x: number, y: number) => number;
  }
) {
  const { width, height, cell, angle, grow } = options;
  const c = Math.cos(angle);
  const s = Math.sin(angle);
  const reach = Math.hypot(width, height) / 2 + cell;
  const n = Math.ceil(reach / cell);
  const ox = width / 2;
  const oy = height / 2;
  const max = cell * 0.5 * 1.18;
  for (let j = -n; j <= n; j++) {
    for (let i = -n; i <= n; i++) {
      const x = ox + (i * c - j * s) * cell;
      const y = oy + (i * s + j * c) * cell;
      if (x < -cell || y < -cell || x > width + cell || y > height + cell) {
        continue;
      }
      const r = max * Math.sqrt(field(x, y)) * (grow ? grow(x, y) : 1);
      if (r > 0.25) {
        ctx.moveTo(x + r, y);
        ctx.arc(x, y, r, 0, Math.PI * 2);
      }
    }
  }
}

export default function HalftoneBackground({
  className,
  children,
  src,
  cell = 9,
  angle = 45,
  loupe = true,
}: HalftoneBackgroundProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const inkRef = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const ctx = canvas?.getContext("2d");
    if (!(root && canvas && ctx && inkRef.current)) {
      return;
    }
    const inkEl = inkRef.current;
    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const pitch = Math.max(cell, 4);
    const theta = (angle * Math.PI) / 180;

    // The full print, drawn once per size or theme, then copied each frame.
    const base = document.createElement("canvas");
    const baseCtx = base.getContext("2d");
    const probe = document
      .createElement("canvas")
      .getContext("2d", { willReadFrequently: true });
    if (!(baseCtx && probe)) {
      return;
    }

    let width = 0;
    let height = 0;
    let dpr = 1;
    let field: Field | null = null;
    let image: HTMLImageElement | null = null;
    let ink = "";
    let invert = false;
    let raf = 0;
    let last = 0;
    let visible = true;
    let introStart = reduceMotion ? -1 : 0;
    const lens = { x: 0, y: 0, tx: 0, ty: 0, r: 0, target: 0, placed: false };

    const readTheme = () => {
      const color = getComputedStyle(inkEl).color;
      // Light ink means a dark page: print the light, not the shadow, so
      // the picture still reads the right way round. Read through a 1px
      // canvas, which understands any CSS color, oklch included.
      probe.clearRect(0, 0, 1, 1);
      probe.fillStyle = color;
      probe.fillRect(0, 0, 1, 1);
      const [r, g, b] = probe.getImageData(0, 0, 1, 1).data;
      const light = (0.2126 * r + 0.7152 * g + 0.0722 * b) / 255 > 0.5;
      const key = `${color}|${light}`;
      if (key === ink) {
        return false;
      }
      ink = key;
      invert = light;
      return true;
    };

    const introGrow = (now: number) => {
      if (introStart === 0) {
        // Waiting to scroll into view: nothing printed yet.
        return () => 0;
      }
      if (introStart < 0) {
        return undefined;
      }
      const t = (now - introStart) / INTRO_MS;
      // A diagonal sweep, each dot easing out as the front passes it.
      return (x: number, y: number) => {
        const front = t * 1.5 - (x + y) / (width + height);
        const k = Math.min(Math.max(front * 3, 0), 1);
        return 1 - (1 - k) ** 3;
      };
    };

    const renderBase = (now = performance.now()) => {
      if (!field) {
        return;
      }
      baseCtx.setTransform(dpr, 0, 0, dpr, 0, 0);
      baseCtx.clearRect(0, 0, width, height);
      baseCtx.fillStyle = getComputedStyle(inkEl).color;
      baseCtx.beginPath();
      screen(baseCtx, field, {
        width,
        height,
        cell: pitch,
        angle: theta,
        grow: introGrow(now),
      });
      baseCtx.fill();
    };

    const draw = () => {
      ctx.setTransform(1, 0, 0, 1, 0, 0);
      ctx.clearRect(0, 0, canvas.width, canvas.height);
      ctx.drawImage(base, 0, 0);
      if (!field || lens.r < 1) {
        return;
      }
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      // Under the loupe: clear the coarse print, then print finer.
      ctx.save();
      ctx.beginPath();
      ctx.arc(lens.x, lens.y, lens.r, 0, Math.PI * 2);
      ctx.clip();
      ctx.clearRect(lens.x - lens.r, lens.y - lens.r, lens.r * 2, lens.r * 2);
      ctx.fillStyle = getComputedStyle(inkEl).color;
      ctx.beginPath();
      const size = lens.r * 2 + pitch;
      const fine = pitch / LOUPE_DETAIL;
      ctx.translate(lens.x - size / 2, lens.y - size / 2);
      const local: Field = (x, y) =>
        (field as Field)(x + lens.x - size / 2, y + lens.y - size / 2);
      screen(ctx, local, {
        width: size,
        height: size,
        cell: fine,
        angle: theta,
      });
      ctx.fill();
      ctx.restore();
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      ctx.beginPath();
      ctx.arc(lens.x, lens.y, lens.r - 0.5, 0, Math.PI * 2);
      ctx.strokeStyle = getComputedStyle(inkEl).color;
      ctx.globalAlpha = 0.25;
      ctx.lineWidth = 1;
      ctx.stroke();
      ctx.globalAlpha = 1;
    };

    const build = () => {
      const rect = canvas.getBoundingClientRect();
      if (rect.width < 2 || rect.height < 2) {
        return;
      }
      width = rect.width;
      height = rect.height;
      dpr = Math.min(window.devicePixelRatio || 1, 2);
      canvas.width = Math.round(width * dpr);
      canvas.height = Math.round(height * dpr);
      base.width = canvas.width;
      base.height = canvas.height;
      field =
        (image?.complete && image.naturalWidth > 0
          ? imageField(image, width, height, invert)
          : null) ?? sphereField(width, height, invert);
      renderBase();
      draw();
    };

    const frame = (now: number) => {
      raf = 0;
      if (!visible) {
        return;
      }
      const dt = last ? Math.min((now - last) / 1000, 0.1) : 1 / 60;
      last = now;
      let busy = false;
      if (introStart > 0) {
        renderBase(now);
        if (now - introStart > INTRO_MS * 1.6) {
          introStart = -1;
          renderBase(now);
        } else {
          busy = true;
        }
      }
      const k = 1 - Math.exp(-dt / LOUPE_LAG);
      lens.x += (lens.tx - lens.x) * k;
      lens.y += (lens.ty - lens.y) * k;
      // The loupe opens and closes quickly, and never from nothing.
      lens.r += (lens.target - lens.r) * (1 - Math.exp(-dt / 0.06));
      if (lens.target === 0 && lens.r < LOUPE * 0.4) {
        lens.r = 0;
      }
      busy ||=
        Math.abs(lens.tx - lens.x) + Math.abs(lens.ty - lens.y) > 0.3 ||
        Math.abs(lens.target - lens.r) > 0.3;
      draw();
      if (busy) {
        raf = requestAnimationFrame(frame);
      }
    };

    const start = () => {
      if (!raf && visible) {
        last = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    readTheme();
    canvas.style.opacity = "1";

    if (src) {
      image = new Image();
      image.crossOrigin = "anonymous";
      image.decoding = "async";
      image.onload = () => {
        build();
        start();
      };
      image.src = src;
    }
    build();

    let size = "";
    const resizeObserver = new ResizeObserver(() => {
      const next = `${canvas.clientWidth}x${canvas.clientHeight}`;
      if (next !== size) {
        size = next;
        build();
      }
    });
    resizeObserver.observe(canvas);

    const intersection = new IntersectionObserver(
      ([entry]) => {
        visible =
          entry.isIntersecting && document.visibilityState === "visible";
        if (visible && introStart === 0 && entry.intersectionRatio > 0.3) {
          introStart = performance.now();
        }
        start();
      },
      { threshold: [0, 0.3] }
    );
    intersection.observe(root);
    const onVisibility = () => {
      visible = document.visibilityState === "visible";
      start();
    };
    document.addEventListener("visibilitychange", onVisibility);

    // Follow light and dark mode without asking the app for a theme.
    const themeTimer = window.setInterval(() => {
      if (readTheme()) {
        build();
      }
    }, 500);

    const place = (event: PointerEvent) => {
      const rect = canvas.getBoundingClientRect();
      lens.tx = event.clientX - rect.left;
      lens.ty = event.clientY - rect.top;
      if (!lens.placed || reduceMotion) {
        lens.x = lens.tx;
        lens.y = lens.ty;
        lens.placed = true;
      }
      lens.target = LOUPE;
      if (reduceMotion) {
        lens.r = LOUPE;
      }
      start();
    };
    const onMove = (event: PointerEvent) => {
      if (event.pointerType === "mouse" || event.buttons) {
        place(event);
      }
    };
    const onHide = () => {
      lens.target = 0;
      lens.placed = false;
      if (reduceMotion) {
        lens.r = 0;
      }
      start();
    };
    const onUp = (event: PointerEvent) => {
      if (event.pointerType !== "mouse") {
        onHide();
      }
    };
    if (loupe) {
      root.addEventListener("pointermove", onMove);
      root.addEventListener("pointerdown", place);
      root.addEventListener("pointerup", onUp);
      root.addEventListener("pointercancel", onHide);
      root.addEventListener("pointerleave", onHide);
    }

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      window.clearInterval(themeTimer);
      if (image) {
        image.onload = null;
      }
      root.removeEventListener("pointermove", onMove);
      root.removeEventListener("pointerdown", place);
      root.removeEventListener("pointerup", onUp);
      root.removeEventListener("pointercancel", onHide);
      root.removeEventListener("pointerleave", onHide);
    };
  }, [src, cell, angle, loupe]);

  return (
    <div
      className={cn(
        "@container relative flex min-h-[560px] w-full touch-pan-y items-center overflow-hidden bg-white text-zinc-900 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={rootRef}
    >
      {/* Ink color for the canvas, so the dots follow the theme. */}
      <span className="hidden text-zinc-900 dark:text-zinc-300" ref={inkRef} />
      <div aria-hidden="true" className="pointer-events-none absolute inset-0">
        <canvas
          className="h-full w-full opacity-0 transition-opacity duration-300 ease-out"
          ref={canvasRef}
        />
      </div>
      {children === undefined ? <DefaultContent /> : children}
    </div>
  );
}

function DefaultContent() {
  return (
    <div className="pointer-events-none relative @3xl:mx-0 mx-auto flex max-w-md flex-col @3xl:items-start items-center gap-4 self-end @3xl:self-center px-6 @3xl:pb-0 pb-16 @3xl:pl-16 @3xl:text-left text-center">
      <h1 className="font-semibold @3xl:text-5xl text-4xl tracking-tight">
        Printed in dots
      </h1>
      <p className="max-w-sm text-base text-zinc-600 dark:text-zinc-400">
        Any picture as a halftone screen. Hover or drag across it to look closer
        through the loupe.
      </p>
    </div>
  );
}
```


---

# Shape Hero
> A landing hero where shapes drop in, pile up under the headline and can be grabbed and thrown.

Source: https://kokonutui.com/docs/backgrounds/shape-hero

## Installation

```bash
npx shadcn@latest add @kokonutui/shape-hero
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Shape Hero
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface HeroShape {
  id: string;
  /** Text or an icon inside the shape. Leave empty for a plain shape. */
  content?: ReactNode;
  /**
   * Size, color and rounding. Every shape is treated as a pill: as wide as
   * it renders, with fully round ends, so a square box becomes a circle.
   */
  className?: string;
}

export interface ShapeHeroProps {
  className?: string;
  /** Small line above the title, such as a badge or a link. */
  eyebrow?: ReactNode;
  title?: ReactNode;
  description?: ReactNode;
  /** Call-to-action buttons under the description. */
  actions?: ReactNode;
  /** Heading element for the title, so the page decides where its `h1` is. */
  as?: "h1" | "h2" | "h3" | "p";
  /** Shapes that drop into the hero, pile up and can be thrown around. */
  shapes?: HeroShape[];
  /** Share of the hero's area the pile may fill; extra shapes are left out. */
  fill?: number;
}

/* ---------------------------------------------------------------------------
 * A small rigid-body solver for pills (capsules): a segment with a radius.
 * Fixed 120Hz steps, sequential impulses with friction, and the whole pile
 * sleeps once it settles, so a resting hero costs nothing.
 * ------------------------------------------------------------------------ */

const STEP = 1 / 120;
const GRAVITY = 2600;
const ITERATIONS = 16;
const FRICTION = 0.5;
const RESTITUTION = 0.22;
const BOUNCE_THRESHOLD = 140;
const SLOP = 0.4;
const CORRECTION = 0.3;
const MAX_SPEED = 3200;
const MAX_SPIN = 18;
const SLEEP_SPEED = 9;
const SLEEP_STEPS = 40;
/** Below this speed a body is nearly at rest: damp it so a pile can't creep. */
const REST_SPEED = 30;
const DRAG_REACH = 0.28;

interface Body {
  x: number;
  y: number;
  a: number;
  vx: number;
  vy: number;
  w: number;
  /** Half the length of the pill's spine. 0 for a circle. */
  half: number;
  r: number;
  invMass: number;
  invInertia: number;
  width: number;
  height: number;
  el: HTMLElement;
}

interface Contact {
  a: Body;
  b: Body | null;
  /** Normal pointing from `b` towards `a`. */
  nx: number;
  ny: number;
  rax: number;
  ray: number;
  rbx: number;
  rby: number;
  depth: number;
  correct: boolean;
  target: number;
  kn: number;
  kt: number;
  jn: number;
  jt: number;
}

interface Drag {
  body: Body;
  /** Grab point in the body's own frame. */
  lx: number;
  ly: number;
  tx: number;
  ty: number;
  id: number;
}

type Point = [number, number];

function ends(body: Body): Point[] {
  if (body.half === 0) {
    return [[body.x, body.y]];
  }
  const c = Math.cos(body.a) * body.half;
  const s = Math.sin(body.a) * body.half;
  return [
    [body.x - c, body.y - s],
    [body.x + c, body.y + s],
  ];
}

function closest(p: Point, seg: Point[]): Point {
  const [a, b = a] = seg;
  const dx = b[0] - a[0];
  const dy = b[1] - a[1];
  const length = dx * dx + dy * dy;
  const t =
    length === 0
      ? 0
      : Math.min(
          Math.max(((p[0] - a[0]) * dx + (p[1] - a[1]) * dy) / length, 0),
          1
        );
  return [a[0] + dx * t, a[1] + dy * t];
}

function contact(
  a: Body,
  b: Body | null,
  nx: number,
  ny: number,
  px: number,
  py: number,
  depth: number
): Contact {
  return {
    a,
    b,
    nx,
    ny,
    rax: px - a.x,
    ray: py - a.y,
    rbx: b ? px - b.x : 0,
    rby: b ? py - b.y : 0,
    depth,
    correct: true,
    target: 0,
    kn: 0,
    kt: 0,
    jn: 0,
    jt: 0,
  };
}

/** Contacts between two pills: each end of one against the other's spine. */
function collidePair(a: Body, b: Body, out: Contact[]) {
  const reach = a.r + b.r;
  const spineA = ends(a);
  const spineB = ends(b);
  const found: Contact[] = [];
  const test = (p: Point, q: Point, fromB: boolean) => {
    const dx = fromB ? q[0] - p[0] : p[0] - q[0];
    const dy = fromB ? q[1] - p[1] : p[1] - q[1];
    const distance = Math.hypot(dx, dy);
    if (distance >= reach + 0.5) {
      return;
    }
    const nx = distance > 1e-6 ? dx / distance : 0;
    const ny = distance > 1e-6 ? dy / distance : -1;
    // Contact point halfway between the two surfaces.
    const [ax, ay] = fromB ? q : p;
    const px = ax - nx * (a.r - (reach - distance) / 2);
    const py = ay - ny * (a.r - (reach - distance) / 2);
    found.push(contact(a, b, nx, ny, px, py, reach - distance));
  };
  for (const p of spineA) {
    test(p, closest(p, spineB), false);
  }
  for (const p of spineB) {
    test(p, closest(p, spineA), true);
  }
  if (found.length === 0) {
    // Spines that cross in the middle: compare their centers' closest points.
    const p = closest([b.x, b.y], spineA);
    test(p, closest(p, spineB), false);
  }
  // Only the deepest contact pushes the pair apart, so they don't overshoot.
  let deepest: Contact | null = null;
  for (const c of found) {
    c.correct = false;
    if (!deepest || c.depth > deepest.depth) {
      deepest = c;
    }
    out.push(c);
  }
  if (deepest) {
    deepest.correct = true;
  }
}

function collideWalls(
  body: Body,
  width: number,
  height: number,
  out: Contact[]
) {
  let deepest: Contact | null = null;
  const add = (c: Contact) => {
    c.correct = false;
    if (!deepest || c.depth > deepest.depth) {
      deepest = c;
    }
    out.push(c);
  };
  for (const [x, y] of ends(body)) {
    if (y + body.r - height > -0.5) {
      add(contact(body, null, 0, -1, x, height, y + body.r - height));
    }
    if (body.r - x > -0.5) {
      add(contact(body, null, 1, 0, 0, y, body.r - x));
    }
    if (x + body.r - width > -0.5) {
      add(contact(body, null, -1, 0, width, y, x + body.r - width));
    }
  }
  if (deepest) {
    (deepest as Contact).correct = true;
  }
}

function relativeVelocity(c: Contact): Point {
  const { a, b } = c;
  let vx = a.vx - a.w * c.ray;
  let vy = a.vy + a.w * c.rax;
  if (b) {
    vx -= b.vx - b.w * c.rby;
    vy -= b.vy + b.w * c.rbx;
  }
  return [vx, vy];
}

function applyImpulse(c: Contact, jx: number, jy: number) {
  const { a, b } = c;
  a.vx += jx * a.invMass;
  a.vy += jy * a.invMass;
  a.w += a.invInertia * (c.rax * jy - c.ray * jx);
  if (b) {
    b.vx -= jx * b.invMass;
    b.vy -= jy * b.invMass;
    b.w -= b.invInertia * (c.rbx * jy - c.rby * jx);
  }
}

function effectiveMass(c: Contact, nx: number, ny: number) {
  const { a, b } = c;
  const ra = c.rax * ny - c.ray * nx;
  let k = a.invMass + a.invInertia * ra * ra;
  if (b) {
    const rb = c.rbx * ny - c.rby * nx;
    k += b.invMass + b.invInertia * rb * rb;
  }
  return k;
}

function prepare(c: Contact) {
  c.kn = effectiveMass(c, c.nx, c.ny);
  c.kt = effectiveMass(c, -c.ny, c.nx);
  const [vx, vy] = relativeVelocity(c);
  const vn = vx * c.nx + vy * c.ny;
  if (c.depth < 0) {
    // Not touching yet: allow it to close the gap this step, no more.
    c.target = c.depth / STEP;
  } else {
    c.target = vn < -BOUNCE_THRESHOLD ? -RESTITUTION * vn : 0;
  }
}

function solve(c: Contact) {
  let [vx, vy] = relativeVelocity(c);
  const vn = vx * c.nx + vy * c.ny;
  const jn = Math.max(c.jn + (c.target - vn) / c.kn, 0);
  const dn = jn - c.jn;
  c.jn = jn;
  applyImpulse(c, c.nx * dn, c.ny * dn);

  [vx, vy] = relativeVelocity(c);
  const tx = -c.ny;
  const ty = c.nx;
  const limit = FRICTION * c.jn;
  const jt = Math.min(
    Math.max(c.jt - (vx * tx + vy * ty) / c.kt, -limit),
    limit
  );
  const dt = jt - c.jt;
  c.jt = jt;
  applyImpulse(c, tx * dt, ty * dt);
}

function correct(c: Contact) {
  if (!c.correct || c.depth <= SLOP) {
    return;
  }
  const { a, b } = c;
  const total = a.invMass + (b ? b.invMass : 0);
  const push = ((c.depth - SLOP) * CORRECTION) / total;
  a.x += c.nx * push * a.invMass;
  a.y += c.ny * push * a.invMass;
  if (b) {
    b.x -= c.nx * push * b.invMass;
    b.y -= c.ny * push * b.invMass;
  }
}

/** Pull the grabbed point towards the pointer, through the body's mass. */
function applyDrag(drag: Drag) {
  const { body } = drag;
  const cos = Math.cos(body.a);
  const sin = Math.sin(body.a);
  const rx = drag.lx * cos - drag.ly * sin;
  const ry = drag.lx * sin + drag.ly * cos;
  const handle = contact(body, null, 0, 0, body.x + rx, body.y + ry, 0);
  const [vx] = relativeVelocity(handle);
  const wantX = ((drag.tx - body.x - rx) / STEP) * DRAG_REACH;
  const wantY = ((drag.ty - body.y - ry) / STEP) * DRAG_REACH;
  applyImpulse(handle, (wantX - vx) / effectiveMass(handle, 1, 0), 0);
  const [, vy] = relativeVelocity(handle);
  applyImpulse(handle, 0, (wantY - vy) / effectiveMass(handle, 0, 1));
  // Hang calmly from the grab point rather than spin.
  body.w *= 0.96;
}

function clampSpeed(body: Body) {
  const speed = Math.hypot(body.vx, body.vy);
  if (speed > MAX_SPEED) {
    body.vx *= MAX_SPEED / speed;
    body.vy *= MAX_SPEED / speed;
  }
  body.w = Math.min(Math.max(body.w, -MAX_SPIN), MAX_SPIN);
}

interface World {
  bodies: Body[];
  width: number;
  height: number;
  drag: Drag | null;
  still: number;
}

/** Advance one fixed step. Returns true once everything has come to rest. */
function step(world: World) {
  const { bodies, width, height, drag } = world;
  for (const body of bodies) {
    body.vy += GRAVITY * STEP;
    body.vx *= 0.999;
    body.w *= 0.995;
  }
  if (drag) {
    applyDrag(drag);
  }
  const contacts: Contact[] = [];
  for (let i = 0; i < bodies.length; i++) {
    collideWalls(bodies[i], width, height, contacts);
    for (let j = i + 1; j < bodies.length; j++) {
      const a = bodies[i];
      const b = bodies[j];
      const near = a.half + a.r + b.half + b.r;
      if (Math.abs(a.x - b.x) < near && Math.abs(a.y - b.y) < near) {
        collidePair(a, b, contacts);
      }
    }
  }
  for (const c of contacts) {
    prepare(c);
  }
  for (let k = 0; k < ITERATIONS; k++) {
    for (const c of contacts) {
      solve(c);
    }
  }
  let fastest = 0;
  for (const body of bodies) {
    clampSpeed(body);
    if (
      body !== drag?.body &&
      Math.hypot(body.vx, body.vy) + Math.abs(body.w) * body.r < REST_SPEED
    ) {
      body.vx *= 0.8;
      body.vy *= 0.8;
      body.w *= 0.8;
    }
    body.x += body.vx * STEP;
    body.y += body.vy * STEP;
    body.a += body.w * STEP;
    fastest = Math.max(
      fastest,
      Math.hypot(body.vx, body.vy) + Math.abs(body.w) * (body.half + body.r)
    );
  }
  for (const c of contacts) {
    correct(c);
  }
  world.still = fastest < SLEEP_SPEED && !drag ? world.still + 1 : 0;
  return world.still > SLEEP_STEPS;
}

function render(bodies: Body[]) {
  for (const body of bodies) {
    body.el.style.transform = `translate3d(${(body.x - body.width / 2).toFixed(2)}px, ${(body.y - body.height / 2).toFixed(2)}px, 0) rotate(${body.a.toFixed(4)}rad)`;
  }
}

/** Deterministic scatter, so the drop looks the same on every visit. */
const scatter = (n: number) => (Math.sin(n * 12.9898) * 43_758.5453) % 1;

function createBodies(
  elements: HTMLElement[],
  width: number,
  height: number,
  fill: number
) {
  const bodies: Body[] = [];
  let area = 0;
  for (const [index, el] of elements.entries()) {
    const w = el.offsetWidth;
    const h = el.offsetHeight;
    if (area + w * h > width * height * fill) {
      el.style.visibility = "hidden";
      continue;
    }
    area += w * h;
    const r = Math.min(w, h) / 2;
    const mass = (w * h) / 1000;
    bodies.push({
      x: width * (0.2 + 0.6 * Math.abs(scatter(index + 1))),
      // Dropped in from above, one after another.
      y: -h - index * 64,
      a: scatter(index + 7) * 0.9,
      vx: scatter(index + 3) * 120,
      vy: 0,
      w: scatter(index + 5) * 2,
      half: Math.max(w - h, 0) / 2,
      r,
      invMass: 1 / mass,
      invInertia: 12 / (mass * (w * w + h * h)),
      width: w,
      height: h,
      el,
    });
    el.style.visibility = "visible";
  }
  return bodies;
}

function hitTest(bodies: Body[], x: number, y: number) {
  for (let i = bodies.length - 1; i >= 0; i--) {
    const body = bodies[i];
    const [qx, qy] = closest([x, y], ends(body));
    if (Math.hypot(x - qx, y - qy) <= body.r) {
      return body;
    }
  }
  return null;
}

export default function ShapeHero({
  className,
  eyebrow,
  title = "Components with a little gravity",
  description = "Copy-paste components for React, built with Tailwind CSS and Motion. Grab a shape and throw it.",
  actions = <DefaultActions />,
  as: Heading = "h1",
  shapes = DEFAULT_SHAPES,
  fill = 0.3,
}: ShapeHeroProps) {
  const rootRef = useRef<HTMLElement>(null);
  const layerRef = useRef<HTMLDivElement>(null);

  // biome-ignore lint/correctness/useExhaustiveDependencies: restarts the drop when the set of shapes changes, not on every new array.
  useEffect(() => {
    const root = rootRef.current;
    const layer = layerRef.current;
    if (!(root && layer)) {
      return;
    }
    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const elements = [...layer.querySelectorAll<HTMLElement>("[data-shape]")];
    const world: World = {
      bodies: [],
      width: layer.clientWidth,
      height: layer.clientHeight,
      drag: null,
      still: 0,
    };
    let raf = 0;
    let last = 0;
    let carry = 0;
    let started = false;
    let visible = false;
    let cancelled = false;

    const loop = (now: number) => {
      raf = 0;
      carry += Math.min((now - last) / 1000, 0.05);
      last = now;
      let asleep = false;
      while (carry >= STEP) {
        asleep = step(world);
        carry -= STEP;
      }
      render(world.bodies);
      if (!asleep && visible) {
        raf = requestAnimationFrame(loop);
      }
    };
    const wake = () => {
      world.still = 0;
      if (!raf && started && visible) {
        last = performance.now();
        raf = requestAnimationFrame(loop);
      }
    };
    const begin = () => {
      if (started || cancelled) {
        return;
      }
      started = true;
      world.bodies = createBodies(elements, world.width, world.height, fill);
      if (reduceMotion) {
        // Settle the pile up front and show it at rest.
        let steps = 0;
        while (steps < 2400 && !step(world)) {
          steps++;
        }
        render(world.bodies);
        return;
      }
      render(world.bodies);
      wake();
    };

    const intersection = new IntersectionObserver(
      ([entry]) => {
        visible = entry.isIntersecting && !document.hidden;
        if (visible) {
          // Wait for fonts, so each shape is measured at its final width.
          document.fonts.ready.then(begin);
          wake();
        }
      },
      { threshold: 0.3 }
    );
    intersection.observe(root);
    const onVisibility = () => {
      visible = !document.hidden;
      wake();
    };
    document.addEventListener("visibilitychange", onVisibility);
    const resizeObserver = new ResizeObserver(() => {
      world.width = layer.clientWidth;
      world.height = layer.clientHeight;
      wake();
    });
    resizeObserver.observe(layer);

    const local = (event: PointerEvent): Point => {
      const rect = layer.getBoundingClientRect();
      return [event.clientX - rect.left, event.clientY - rect.top];
    };
    const onDown = (event: PointerEvent) => {
      if (!started || world.drag || event.button !== 0) {
        return;
      }
      const [x, y] = local(event);
      const body = hitTest(world.bodies, x, y);
      if (!body) {
        return;
      }
      event.preventDefault();
      const dx = x - body.x;
      const dy = y - body.y;
      const cos = Math.cos(-body.a);
      const sin = Math.sin(-body.a);
      world.drag = {
        body,
        lx: dx * cos - dy * sin,
        ly: dx * sin + dy * cos,
        tx: x,
        ty: y,
        id: event.pointerId,
      };
      layer.setPointerCapture(event.pointerId);
      layer.dataset.dragging = "";
      wake();
    };
    const onMove = (event: PointerEvent) => {
      if (world.drag?.id === event.pointerId) {
        [world.drag.tx, world.drag.ty] = local(event);
        wake();
      }
    };
    const onUp = (event: PointerEvent) => {
      if (world.drag?.id === event.pointerId) {
        world.drag = null;
        delete layer.dataset.dragging;
        wake();
      }
    };
    layer.addEventListener("pointerdown", onDown);
    layer.addEventListener("pointermove", onMove);
    layer.addEventListener("pointerup", onUp);
    layer.addEventListener("pointercancel", onUp);

    return () => {
      cancelled = true;
      cancelAnimationFrame(raf);
      intersection.disconnect();
      resizeObserver.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      layer.removeEventListener("pointerdown", onDown);
      layer.removeEventListener("pointermove", onMove);
      layer.removeEventListener("pointerup", onUp);
      layer.removeEventListener("pointercancel", onUp);
    };
  }, [shapes.map((shape) => shape.id).join("|"), fill]);

  return (
    <section
      className={cn(
        "relative flex min-h-[720px] w-full flex-col items-center overflow-hidden bg-white px-6 pt-24 pb-24 text-zinc-900 sm:pt-28 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={rootRef}
    >
      <div
        aria-hidden="true"
        className="group/shapes absolute inset-0 touch-pan-y"
        ref={layerRef}
      >
        {shapes.map((shape) => (
          <div
            className={cn(
              "absolute top-0 left-0 flex cursor-grab touch-none select-none items-center justify-center whitespace-nowrap rounded-full will-change-transform group-data-dragging/shapes:cursor-grabbing",
              shape.className
            )}
            data-shape=""
            key={shape.id}
            style={{ visibility: "hidden" }}
          >
            {shape.content}
          </div>
        ))}
      </div>

      <div className="pointer-events-none relative flex max-w-2xl flex-col items-center text-center">
        {eyebrow ? (
          <div className="pointer-events-auto mb-6">{eyebrow}</div>
        ) : null}
        <Heading className="text-balance font-semibold text-4xl tracking-tight sm:text-6xl">
          {title}
        </Heading>
        {description ? (
          <p className="mt-5 max-w-md text-pretty text-base text-zinc-500 sm:text-lg dark:text-zinc-400">
            {description}
          </p>
        ) : null}
        {actions ? (
          <div className="pointer-events-auto mt-8 flex flex-wrap items-center justify-center gap-3">
            {actions}
          </div>
        ) : null}
      </div>
    </section>
  );
}

function DefaultActions() {
  return (
    <>
      <button
        className="h-10 rounded-full bg-zinc-900 px-5 font-medium text-sm text-white transition-colors duration-150 ease-out hover:bg-zinc-700 dark:bg-white dark:text-zinc-900 dark:hover:bg-zinc-200"
        type="button"
      >
        Browse components
      </button>
      <button
        className="h-10 rounded-full border border-zinc-200 bg-white px-5 font-medium text-sm text-zinc-700 transition-colors duration-150 ease-out hover:bg-zinc-100 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-300 dark:hover:bg-zinc-900"
        type="button"
      >
        Read the docs
      </button>
    </>
  );
}

const PILL = "h-14 px-7 font-medium text-lg tracking-tight";
const OUTLINE =
  "border border-zinc-200 bg-white text-zinc-900 dark:border-zinc-800 dark:bg-zinc-900 dark:text-zinc-100";
const SOLID = "bg-zinc-900 text-white dark:bg-zinc-100 dark:text-zinc-900";
const ACCENT = "bg-orange-500 text-white";

const DEFAULT_SHAPES: HeroShape[] = [
  { id: "pull-cord", content: "Pull Cord", className: cn(PILL, SOLID) },
  { id: "detent-dial", content: "Detent Dial", className: cn(PILL, OUTLINE) },
  { id: "dot-1", className: cn("size-16", ACCENT) },
  { id: "wheel-picker", content: "Wheel Picker", className: cn(PILL, OUTLINE) },
  { id: "topo", content: "Topo", className: cn(PILL, ACCENT) },
  { id: "split-flap", content: "Split Flap", className: cn(PILL, OUTLINE) },
  { id: "dot-2", className: cn("size-12", SOLID) },
  {
    id: "notification-stack",
    content: "Notification Stack",
    className: cn(PILL, OUTLINE),
  },
  { id: "paper-fold", content: "Paper Fold", className: cn(PILL, SOLID) },
  { id: "dot-3", className: cn("size-20", OUTLINE) },
  { id: "toss-board", content: "Toss Board", className: cn(PILL, OUTLINE) },
  { id: "react", content: "React", className: cn(PILL, OUTLINE) },
  { id: "motion", content: "Motion", className: cn(PILL, SOLID) },
  { id: "dot-4", className: cn("size-14", OUTLINE) },
  { id: "tailwind", content: "Tailwind CSS", className: cn(PILL, OUTLINE) },
  { id: "shadcn", content: "shadcn/ui", className: cn(PILL, OUTLINE) },
  { id: "peel-sticker", content: "Peel Sticker", className: cn(PILL, SOLID) },
  { id: "dot-5", className: cn("size-12", ACCENT) },
  {
    id: "background-paths",
    content: "Background Paths",
    className: cn(PILL, OUTLINE),
  },
  { id: "flow-field", content: "Flow Field", className: cn(PILL, OUTLINE) },
  { id: "dot-6", className: cn("size-16", SOLID) },
  { id: "typescript", content: "TypeScript", className: cn(PILL, OUTLINE) },
];
```


---

# Topo Background
> A living contour map that drifts, rises under the cursor and ripples on click, built with React and Canvas.

Source: https://kokonutui.com/docs/backgrounds/topo-background

## Installation

```bash
npx shadcn@latest add @kokonutui/topo-background
```

## Source

```tsx
// biome-ignore-all lint/suspicious/noBitwiseOperators: the noise hash and the marching-squares case index are bit arithmetic.
"use client";

/**
 * @author: @dorianbaffier
 * @description: Topo Background
 * @version: 1.1.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type ReactNode, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface TopoBackgroundProps {
  /**
   * Extra classes for the root. The map draws on a transparent canvas, so
   * `className="bg-transparent"` lays it over your own page background.
   */
  className?: string;
  /** Content shown over the map. Pass `null` for a bare background. */
  children?: ReactNode;
  /** Height difference between two contour lines. Lower draws more lines. */
  interval?: number;
  /** How fast the terrain drifts. 0 holds it still. */
  speed?: number;
  /** Raise a hill under the cursor and send a ripple on click. */
  interactive?: boolean;
  /** Seed for the terrain, so a page always opens on the same map. */
  seed?: number;
  /** Print elevations on the index contours, as on a survey map. */
  labels?: boolean;
}

// Distance between field samples, in CSS px. Contours are traced through
// this grid, so it trades smoothness for work per frame.
const CELL = 12;
// Width of a hill in the terrain, in px.
const TERRAIN_SCALE = 360;
// Every fifth line is an index contour, drawn heavier, as on a real map.
const INDEX_EVERY = 5;
// The hill that follows the cursor: height in field units, and spread (px).
const HILL_HEIGHT = 0.5;
const HILL_SPREAD = 120;
// How quickly the hill catches up with the cursor (per second) and how
// quickly it rises or sinks when the cursor arrives or leaves.
const HILL_FOLLOW = 9;
const HILL_RISE = 5;
// A click sends a ring outwards through the terrain.
const RIPPLE_MS = 1800;
const RIPPLE_SPEED = 0.24; // px per ms
const RIPPLE_WIDTH = 42;
const RIPPLE_HEIGHT = 0.2;
// Distance between the crests of the wave train, in px.
const RIPPLE_WAVELENGTH = 96;
// When nothing is moving but the drift, a frame every 33ms is plenty.
const IDLE_FRAME_MS = 33;
// Elevation labels: one per slot of this size at most (px), riding along
// with the terrain. Elevation of level n is BASE + n * STEP metres, so the
// index contours read as round hundreds.
const LABEL_SPACING = 210;
const LABEL_BASE = 500;
const LABEL_STEP = 20;
// Labels keep clear of the faded top and bottom edges.
const LABEL_MARGIN = 0.16;
const MAX_LABEL_ANGLE = Math.PI / 3;
const LABEL_FONT =
  "500 10px ui-sans-serif, system-ui, -apple-system, Segoe UI, sans-serif";

/** The best spot found so far in each label slot. */
interface LabelSlots {
  drift: number;
  width: number;
  height: number;
  best: Map<number, Label>;
  /** Areas covered by the content, where a number would read as noise. */
  avoid: { x0: number; y0: number; x1: number; y1: number }[];
}

interface Label {
  x: number;
  y: number;
  angle: number;
  level: number;
  /** Squared distance to the slot's centre; the closest candidate wins. */
  score: number;
}

interface Ripple {
  x: number;
  y: number;
  start: number;
}

/** Seeded 3D gradient noise (Ken Perlin's improved noise), about -1 to 1. */
function createNoise(seed: number) {
  const p = Array.from({ length: 256 }, (_, i) => i);
  let state = seed >>> 0 || 1;
  const random = () => {
    state = (state * 1_664_525 + 1_013_904_223) >>> 0;
    return state / 4_294_967_296;
  };
  for (let i = 255; i > 0; i--) {
    const j = Math.floor(random() * (i + 1));
    [p[i], p[j]] = [p[j], p[i]];
  }
  const perm = new Uint8Array(512);
  for (let i = 0; i < 512; i++) {
    perm[i] = p[i & 255];
  }
  const fade = (t: number) => t * t * t * (t * (t * 6 - 15) + 10);
  const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
  const grad = (hash: number, x: number, y: number, z: number) => {
    const h = hash & 15;
    const u = h < 8 ? x : y;
    let v = z;
    if (h < 4) {
      v = y;
    } else if (h === 12 || h === 14) {
      v = x;
    }
    return ((h & 1) === 0 ? u : -u) + ((h & 2) === 0 ? v : -v);
  };

  return (x: number, y: number, z: number) => {
    const X = Math.floor(x) & 255;
    const Y = Math.floor(y) & 255;
    const Z = Math.floor(z) & 255;
    const fx = x - Math.floor(x);
    const fy = y - Math.floor(y);
    const fz = z - Math.floor(z);
    const u = fade(fx);
    const v = fade(fy);
    const w = fade(fz);
    const A = perm[X] + Y;
    const AA = perm[A] + Z;
    const AB = perm[A + 1] + Z;
    const B = perm[X + 1] + Y;
    const BA = perm[B] + Z;
    const BB = perm[B + 1] + Z;
    return lerp(
      lerp(
        lerp(grad(perm[AA], fx, fy, fz), grad(perm[BA], fx - 1, fy, fz), u),
        lerp(
          grad(perm[AB], fx, fy - 1, fz),
          grad(perm[BB], fx - 1, fy - 1, fz),
          u
        ),
        v
      ),
      lerp(
        lerp(
          grad(perm[AA + 1], fx, fy, fz - 1),
          grad(perm[BA + 1], fx - 1, fy, fz - 1),
          u
        ),
        lerp(
          grad(perm[AB + 1], fx, fy - 1, fz - 1),
          grad(perm[BB + 1], fx - 1, fy - 1, fz - 1),
          u
        ),
        v
      ),
      w
    );
  };
}

/**
 * The segment a contour draws through one grid cell, given which corners
 * are above the level (bits: top-left 8, top-right 4, bottom-right 2,
 * bottom-left 1) and where it crosses each edge.
 */
function cellSegments(
  path: Path2D,
  index: number,
  box: { x0: number; y0: number; x1: number; y1: number },
  cross: { top: number; right: number; bottom: number; left: number }
) {
  const { x0, y0, x1, y1 } = box;
  const { top, right, bottom, left } = cross;
  const line = (ax: number, ay: number, bx: number, by: number) => {
    path.moveTo(ax, ay);
    path.lineTo(bx, by);
  };
  switch (index) {
    case 1:
    case 14:
      line(x0, left, bottom, y1);
      break;
    case 2:
    case 13:
      line(bottom, y1, x1, right);
      break;
    case 3:
    case 12:
      line(x0, left, x1, right);
      break;
    case 4:
    case 11:
      line(top, y0, x1, right);
      break;
    case 6:
    case 9:
      line(top, y0, bottom, y1);
      break;
    case 7:
    case 8:
      line(x0, left, top, y0);
      break;
    // The two saddles: opposite corners are high, so the level crosses
    // the cell twice.
    case 5:
      line(x0, left, top, y0);
      line(bottom, y1, x1, right);
      break;
    case 10:
      line(top, y0, x1, right);
      line(x0, left, bottom, y1);
      break;
    default:
      break;
  }
}

/**
 * Offer a point on an index contour as a label spot. Slots are laid out in
 * terrain space (they drift with the map) and every other row is offset by
 * half a slot, so labels scatter instead of lining up in a grid.
 */
function offerLabel(slots: LabelSlots, label: Omit<Label, "score">) {
  const { x, y } = label;
  if (
    y < slots.height * LABEL_MARGIN ||
    y > slots.height * (1 - LABEL_MARGIN) ||
    x < 24 ||
    x > slots.width - 24 ||
    slots.avoid.some((r) => x > r.x0 && x < r.x1 && y > r.y0 && y < r.y1)
  ) {
    return;
  }
  const row = Math.floor(y / LABEL_SPACING);
  const shifted = x + slots.drift + (row % 2) * (LABEL_SPACING / 2);
  const col = Math.floor(shifted / LABEL_SPACING);
  const cx = (col + 0.5) * LABEL_SPACING;
  const cy = (row + 0.5) * LABEL_SPACING;
  const score = (shifted - cx) ** 2 + (y - cy) ** 2;
  // Too far from the slot centre: a neighbouring label could sit right
  // next to it.
  if (score > (LABEL_SPACING * 0.32) ** 2) {
    return;
  }
  const key = row * 100_000 + col;
  const current = slots.best.get(key);
  if (!current || score < current.score) {
    slots.best.set(key, { ...label, score });
  }
}

/** Offer the middle of a cell an index contour passes through. */
function offerCellLabel(
  slots: LabelSlots,
  [a, b, c, d]: [number, number, number, number],
  x0: number,
  y0: number,
  level: number,
  t: number
) {
  // The contour runs across the slope; the cell's gradient gives a steadier
  // direction than the short segment itself.
  const gx = b - a + c - d;
  const gy = d - a + c - b;
  // Slide from the cell's centre along the slope onto the line itself.
  const px = gx / (2 * CELL);
  const py = gy / (2 * CELL);
  const g2 = px * px + py * py;
  const lift = g2 > 0 ? (t - (a + b + c + d) / 4) / g2 : 0;
  const half = CELL / 2;
  const ox = Math.max(-half, Math.min(half, lift * px));
  const oy = Math.max(-half, Math.min(half, lift * py));
  let angle = Math.atan2(gx, -gy);
  // Keep text upright, and skip steep stretches: a number on its side is
  // hard to read.
  if (angle > Math.PI / 2) {
    angle -= Math.PI;
  } else if (angle < -Math.PI / 2) {
    angle += Math.PI;
  }
  if (Math.abs(angle) > MAX_LABEL_ANGLE) {
    return;
  }
  offerLabel(slots, { x: x0 + half + ox, y: y0 + half + oy, angle, level });
}

/** Every contour level that passes through one cell, usually none or one. */
function traceCell(
  field: Float32Array,
  cols: number,
  i: number,
  j: number,
  interval: number,
  paths: { minor: Path2D; major: Path2D; slots: LabelSlots | null }
) {
  const a = field[j * cols + i];
  const b = field[j * cols + i + 1];
  const c = field[(j + 1) * cols + i + 1];
  const d = field[(j + 1) * cols + i];
  const x0 = i * CELL;
  const y0 = j * CELL;
  const first = Math.ceil(Math.min(a, b, c, d) / interval);
  const last = Math.floor(Math.max(a, b, c, d) / interval);
  if (first > last) {
    return;
  }
  const box = { x0, y0, x1: x0 + CELL, y1: y0 + CELL };
  for (let level = first; level <= last; level++) {
    const t = level * interval;
    const index =
      (a > t ? 8 : 0) | (b > t ? 4 : 0) | (c > t ? 2 : 0) | (d > t ? 1 : 0);
    if (index === 0 || index === 15) {
      continue;
    }
    const isIndex = level % INDEX_EVERY === 0;
    cellSegments(isIndex ? paths.major : paths.minor, index, box, {
      top: x0 + CELL * ((t - a) / (b - a)),
      right: y0 + CELL * ((t - b) / (c - b)),
      bottom: x0 + CELL * ((t - d) / (c - d)),
      left: y0 + CELL * ((t - a) / (d - a)),
    });
    // Saddles are poor label spots: the line turns sharply there.
    if (isIndex && paths.slots && index !== 5 && index !== 10) {
      offerCellLabel(paths.slots, [a, b, c, d], x0, y0, level, t);
    }
  }
}

/**
 * Marching squares: for each cell, find where each contour level crosses
 * its edges and join those points. Index contours go into their own path
 * so each group is stroked once.
 */
function traceContours(
  field: Float32Array,
  cols: number,
  rows: number,
  interval: number,
  minor: Path2D,
  major: Path2D,
  slots: LabelSlots | null
) {
  const paths = { minor, major, slots };
  for (let j = 0; j < rows - 1; j++) {
    for (let i = 0; i < cols - 1; i++) {
      traceCell(field, cols, i, j, interval, paths);
    }
  }
}

interface Hill {
  x: number;
  y: number;
  targetX: number;
  targetY: number;
  amount: number;
  on: boolean;
}

/** Ease the hill towards the cursor and up or down. True while it moves. */
function stepHill(hill: Hill, dt: number) {
  const follow = 1 - Math.exp(-HILL_FOLLOW * dt);
  hill.x += (hill.targetX - hill.x) * follow;
  hill.y += (hill.targetY - hill.y) * follow;
  const goal = hill.on ? 1 : 0;
  hill.amount += (goal - hill.amount) * (1 - Math.exp(-HILL_RISE * dt));
  return (
    Math.abs(hill.targetX - hill.x) > 0.5 ||
    Math.abs(hill.targetY - hill.y) > 0.5 ||
    Math.abs(goal - hill.amount) > 0.002
  );
}

export default function TopoBackground({
  className,
  children,
  interval = 0.07,
  speed = 1,
  interactive = true,
  seed = 26,
  labels = true,
}: TopoBackgroundProps) {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const ctx = canvas?.getContext("2d");
    if (!(root && canvas && ctx)) {
      return;
    }

    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const noise = createNoise(seed);

    let width = 0;
    let height = 0;
    let cols = 0;
    let rows = 0;
    let field = new Float32Array(0);
    let color = "";

    // The cursor hill, eased towards the pointer so it glides, not jumps.
    const hill: Hill = {
      x: 0,
      y: 0,
      targetX: 0,
      targetY: 0,
      amount: 0,
      on: false,
    };
    const ripples: Ripple[] = [];
    let time = 0;
    let last = 0;
    let lastPaint = 0;
    let raf = 0;
    let visible = true;

    const resize = () => {
      const rect = canvas.getBoundingClientRect();
      const dpr = Math.min(window.devicePixelRatio || 1, 2);
      width = rect.width;
      height = rect.height;
      canvas.width = Math.round(width * dpr);
      canvas.height = Math.round(height * dpr);
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      cols = Math.ceil(width / CELL) + 1;
      rows = Math.ceil(height / CELL) + 1;
      field = new Float32Array(cols * rows);
      color = getComputedStyle(canvas).color;
      measureContent();
    };

    const sample = (now: number) => {
      const z = time * 0.05;
      const drift = time * 6;
      const hillOn = hill.amount > 0.001;
      const spread = 2 * HILL_SPREAD * HILL_SPREAD;
      const ringWidth = 2 * RIPPLE_WIDTH * RIPPLE_WIDTH;
      for (let j = 0; j < rows; j++) {
        const y = j * CELL;
        for (let i = 0; i < cols; i++) {
          const x = i * CELL;
          const nx = (x + drift) / TERRAIN_SCALE;
          const ny = y / TERRAIN_SCALE;
          let v =
            noise(nx, ny, z) * 0.78 +
            noise(nx * 2.3 + 17.1, ny * 2.3 + 4.7, z * 1.4) * 0.22;
          if (hillOn) {
            const dx = x - hill.x;
            const dy = y - hill.y;
            v +=
              HILL_HEIGHT *
              hill.amount *
              Math.exp(-(dx * dx + dy * dy) / spread);
          }
          for (const ripple of ripples) {
            const age = now - ripple.start;
            const reach = age * RIPPLE_SPEED;
            const d = Math.hypot(x - ripple.x, y - ripple.y) - reach;
            const fadeOut = 1 - age / RIPPLE_MS;
            // A short train of crests and troughs, like a stone dropped in
            // water, so the contours bunch into rings as it passes.
            v +=
              RIPPLE_HEIGHT *
              fadeOut *
              fadeOut *
              Math.exp(-(d * d) / ringWidth) *
              Math.cos((d / RIPPLE_WAVELENGTH) * Math.PI * 2);
          }
          field[j * cols + i] = v;
        }
      }
    };

    const slots: LabelSlots = {
      drift: 0,
      width: 0,
      height: 0,
      best: new Map(),
      avoid: [],
    };
    // Keep labels out from under the content laid over the map.
    const measureContent = () => {
      const origin = canvas.getBoundingClientRect();
      slots.avoid = [];
      for (const child of Array.from(root.children)) {
        if (child.contains(canvas)) {
          continue;
        }
        const r = child.getBoundingClientRect();
        slots.avoid.push({
          x0: r.left - origin.left - 16,
          y0: r.top - origin.top - 12,
          x1: r.right - origin.left + 16,
          y1: r.bottom - origin.top + 12,
        });
      }
    };

    /**
     * Knock the lines out under each label, then print the elevation, so
     * the contour is broken where the number sits, as on a survey map.
     */
    const drawLabels = () => {
      ctx.font = LABEL_FONT;
      ctx.textAlign = "center";
      ctx.textBaseline = "middle";
      for (const label of slots.best.values()) {
        const text = `${LABEL_BASE + label.level * LABEL_STEP}`;
        const w = ctx.measureText(text).width + 8;
        ctx.save();
        ctx.translate(Math.round(label.x), Math.round(label.y));
        ctx.rotate(label.angle);
        ctx.globalCompositeOperation = "destination-out";
        ctx.globalAlpha = 1;
        ctx.fillRect(-w / 2, -6, w, 12);
        ctx.globalCompositeOperation = "source-over";
        ctx.globalAlpha = 0.5;
        ctx.fillText(text, 0, 0.5);
        ctx.restore();
      }
    };

    const paint = (now: number) => {
      sample(now);
      const minor = new Path2D();
      const major = new Path2D();
      slots.best.clear();
      slots.drift = time * 6;
      slots.width = width;
      slots.height = height;
      traceContours(
        field,
        cols,
        rows,
        interval,
        minor,
        major,
        labels ? slots : null
      );
      ctx.clearRect(0, 0, width, height);
      ctx.strokeStyle = color;
      ctx.fillStyle = color;
      ctx.lineCap = "round";
      ctx.globalAlpha = 0.16;
      ctx.lineWidth = 0.75;
      ctx.stroke(minor);
      ctx.globalAlpha = 0.34;
      ctx.lineWidth = 1.1;
      ctx.stroke(major);
      if (labels) {
        drawLabels();
      }
      ctx.globalAlpha = 1;
    };

    const frame = (now: number) => {
      raf = 0;
      if (!visible) {
        return;
      }
      const dt = last ? Math.min((now - last) / 1000, 0.05) : 0;
      last = now;
      const hillMoving = stepHill(hill, dt);
      while (ripples.length > 0 && now - ripples[0].start > RIPPLE_MS) {
        ripples.shift();
      }
      const settling = hillMoving || ripples.length > 0;

      time += dt * speed;
      // The drift alone is slow; half the frame rate looks the same and
      // costs half as much. Anything following the hand gets every frame.
      if (settling || now - lastPaint >= IDLE_FRAME_MS) {
        paint(now);
        lastPaint = now;
      }
      if (speed > 0 || settling) {
        raf = requestAnimationFrame(frame);
      }
    };

    const start = () => {
      if (!raf && visible && !reduceMotion) {
        last = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    // Follow light and dark mode without asking the app for a theme. The
    // check only runs while the map is on screen.
    let colorTimer = 0;
    const checkColor = () => {
      const next = getComputedStyle(canvas).color;
      if (next !== color) {
        color = next;
        if (reduceMotion || !raf) {
          paint(performance.now());
        }
      }
    };
    const watchColor = () => {
      if (visible && !colorTimer) {
        checkColor();
        colorTimer = window.setInterval(checkColor, 500);
      } else if (!visible && colorTimer) {
        window.clearInterval(colorTimer);
        colorTimer = 0;
      }
    };

    resize();
    paint(performance.now());
    canvas.style.opacity = "1";
    start();

    const resizeObserver = new ResizeObserver(() => {
      resize();
      paint(performance.now());
    });
    resizeObserver.observe(canvas);

    // Stop drawing entirely while the map is scrolled away or the tab is
    // in the background.
    let onScreen = true;
    const updateVisible = () => {
      visible = onScreen && document.visibilityState === "visible";
      watchColor();
      if (visible) {
        start();
      }
    };
    const intersection = new IntersectionObserver(([entry]) => {
      onScreen = entry.isIntersecting;
      updateVisible();
    });
    intersection.observe(root);
    document.addEventListener("visibilitychange", updateVisible);
    watchColor();

    const local = (event: PointerEvent) => {
      const rect = canvas.getBoundingClientRect();
      return { x: event.clientX - rect.left, y: event.clientY - rect.top };
    };
    const onMove = (event: PointerEvent) => {
      // Touch has no hover; a hill stuck where a finger lifted looks wrong.
      if (event.pointerType !== "mouse") {
        return;
      }
      const point = local(event);
      if (!hill.on) {
        // Rise where the cursor came in rather than sliding over from the
        // last place it left.
        hill.x = point.x;
        hill.y = point.y;
      }
      hill.targetX = point.x;
      hill.targetY = point.y;
      hill.on = true;
      start();
    };
    const onLeave = () => {
      hill.on = false;
      start();
    };
    const onDown = (event: PointerEvent) => {
      // Clicks on the content (links, buttons) are not meant for the map.
      if ((event.target as HTMLElement).closest("a, button, input, textarea")) {
        return;
      }
      const point = local(event);
      ripples.push({ ...point, start: performance.now() });
      if (ripples.length > 4) {
        ripples.shift();
      }
      start();
    };
    if (interactive && !reduceMotion) {
      root.addEventListener("pointermove", onMove);
      root.addEventListener("pointerleave", onLeave);
      root.addEventListener("pointerdown", onDown);
    }

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", updateVisible);
      window.clearInterval(colorTimer);
      root.removeEventListener("pointermove", onMove);
      root.removeEventListener("pointerleave", onLeave);
      root.removeEventListener("pointerdown", onDown);
    };
  }, [interval, speed, interactive, seed, labels]);

  return (
    <div
      className={cn(
        "relative flex min-h-[560px] w-full items-center justify-center overflow-hidden bg-white text-zinc-900 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={rootRef}
    >
      {/* Faded out top and bottom so the map sits into the page around it. */}
      <div aria-hidden="true" className="pointer-events-none absolute inset-0">
        <canvas
          className="h-full w-full opacity-0 transition-opacity duration-500 ease-out"
          ref={canvasRef}
          style={{
            maskImage:
              "linear-gradient(to bottom, transparent, #000 18%, #000 82%, transparent)",
          }}
        />
      </div>
      {children === undefined ? <DefaultContent /> : children}
    </div>
  );
}

function DefaultContent() {
  return (
    <div className="relative flex max-w-xl flex-col items-center gap-4 px-6 text-center">
      {/* A plain paragraph: the page that uses this decides its own h1. */}
      <p className="text-balance font-semibold text-4xl text-zinc-900 tracking-tight sm:text-5xl dark:text-zinc-100">
        Find your footing
      </p>
      <p className="max-w-sm text-base text-zinc-500 dark:text-zinc-400">
        A living contour map. Move the cursor to raise a hill, click to send a
        ripple across it.
      </p>
    </div>
  );
}
```


---

# Magnet Button
> Magnetic button that pulls floating particles to its center on hover using Motion spring animations, built with React and Tailwind CSS.

Source: https://kokonutui.com/docs/buttons/attract-button

## Installation

```bash
npx shadcn@latest add @kokonutui/attract-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Attract Button
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { Magnet } from "lucide-react";
import { motion, type Transition, useReducedMotion } from "motion/react";
import {
  type ComponentProps,
  type FocusEvent,
  type PointerEvent,
  useEffect,
  useState,
} from "react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

interface AttractButtonProps extends ComponentProps<"button"> {
  particleCount?: number;
  /** Max distance in px that particles scatter from the button's center. */
  attractRadius?: number;
}

interface Particle {
  id: number;
  x: number;
  y: number;
}

const SPRING: Transition = { type: "spring", duration: 0.5, bounce: 0.2 };

export default function AttractButton({
  className,
  children,
  particleCount = 12,
  attractRadius = 180,
  onPointerEnter,
  onPointerLeave,
  onPointerDown,
  onPointerUp,
  onPointerCancel,
  onFocus,
  onBlur,
  ...props
}: AttractButtonProps) {
  const [isPointerAttracting, setIsPointerAttracting] = useState(false);
  const [isFocusVisible, setIsFocusVisible] = useState(false);
  const [particles, setParticles] = useState<Particle[]>([]);
  const shouldReduceMotion = useReducedMotion();

  useEffect(() => {
    setParticles(
      Array.from({ length: particleCount }, (_, i) => ({
        id: i,
        x: (Math.random() * 2 - 1) * attractRadius,
        y: (Math.random() * 2 - 1) * attractRadius,
      }))
    );
  }, [particleCount, attractRadius]);

  // Mouse attracts on hover. Touch and pen attract only while pressed, so a
  // tap can't leave the button stuck in the attracting state.
  const handlePointerEnter = (event: PointerEvent<HTMLButtonElement>) => {
    onPointerEnter?.(event);
    if (event.pointerType === "mouse") {
      setIsPointerAttracting(true);
    }
  };

  const handlePointerLeave = (event: PointerEvent<HTMLButtonElement>) => {
    onPointerLeave?.(event);
    if (event.pointerType === "mouse") {
      setIsPointerAttracting(false);
    }
  };

  const handlePointerDown = (event: PointerEvent<HTMLButtonElement>) => {
    onPointerDown?.(event);
    if (event.pointerType !== "mouse") {
      setIsPointerAttracting(true);
    }
  };

  const handlePointerUp = (event: PointerEvent<HTMLButtonElement>) => {
    onPointerUp?.(event);
    if (event.pointerType !== "mouse") {
      setIsPointerAttracting(false);
    }
  };

  const handlePointerCancel = (event: PointerEvent<HTMLButtonElement>) => {
    onPointerCancel?.(event);
    if (event.pointerType !== "mouse") {
      setIsPointerAttracting(false);
    }
  };

  // Keyboard focus attracts too. Mouse clicks also focus the button, so only
  // :focus-visible counts, which keeps a click from holding the effect on.
  const handleFocus = (event: FocusEvent<HTMLButtonElement>) => {
    onFocus?.(event);
    setIsFocusVisible(event.currentTarget.matches(":focus-visible"));
  };

  const handleBlur = (event: FocusEvent<HTMLButtonElement>) => {
    onBlur?.(event);
    setIsFocusVisible(false);
  };

  const isAttracting = isPointerAttracting || isFocusVisible;
  const pullIn = isAttracting && !shouldReduceMotion;

  return (
    <Button
      {...props}
      className={cn(
        "relative min-w-40",
        "bg-violet-100 dark:bg-violet-900",
        "hover:bg-violet-200 dark:hover:bg-violet-800",
        "text-violet-600 dark:text-violet-300",
        "border border-violet-300 dark:border-violet-700",
        "transition-[color,background-color,border-color,scale] duration-150 ease-out active:scale-[0.97]",
        className
      )}
      onBlur={handleBlur}
      onFocus={handleFocus}
      onPointerCancel={handlePointerCancel}
      onPointerDown={handlePointerDown}
      onPointerEnter={handlePointerEnter}
      onPointerLeave={handlePointerLeave}
      onPointerUp={handlePointerUp}
    >
      {particles.map((particle) => (
        <motion.div
          animate={pullIn ? { x: 0, y: 0 } : { x: particle.x, y: particle.y }}
          aria-hidden="true"
          className={cn(
            "pointer-events-none absolute h-1.5 w-1.5 rounded-full",
            "bg-violet-400 dark:bg-violet-300",
            "transition-opacity duration-300",
            isAttracting ? "opacity-100" : "opacity-40"
          )}
          initial={{ x: particle.x, y: particle.y }}
          key={particle.id}
          transition={SPRING}
        />
      ))}
      <span className="relative flex w-full items-center justify-center gap-2">
        <Magnet
          className={cn(
            "h-4 w-4 transition-transform duration-300",
            isAttracting && "motion-safe:scale-110"
          )}
        />
        {children ?? (isAttracting ? "Attracting" : "Hover me")}
      </span>
    </Button>
  );
}
```


---

# Bell Button
> A subscribe button whose bell swings and rings, with a clapper that really strikes.

Source: https://kokonutui.com/docs/buttons/bell-button

## Installation

```bash
npx shadcn@latest add @kokonutui/bell-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Bell Button
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type PointerEvent,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// The bell and its clapper are two pendulums on the same pivot. Nothing
// couples them but collisions: the swinging bell catches the clapper with
// its lip, flings it across, and it strikes the other side. Angles in deg,
// time in seconds.
const STEP = 1 / 240;
const BELL_STIFFNESS = 380;
const BELL_DAMPING = 5;
const CLAPPER_STIFFNESS = 150;
const CLAPPER_DAMPING = 4;
// How far the clapper can swing inside the bell before it hits the lip.
const LIP = 13;
const RESTITUTION = 0.45;
// Share of a hit that goes into the bell, which is much heavier.
const RECOIL = 0.18;
// Impacts harder than this ring out (deg/s, relative).
const STRIKE_SPEED = 260;
const RING_KICK = 600;
const NUDGE_KICK = 160;
const MUTE_KICK = 300;
const REST = 0.05;
const PIVOT = { x: 12, y: 2.5 };
const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";

function haptic(ms: number) {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(ms);
  }
}

/** A number whose digits roll to their new value, like a counter. */
function RollingNumber({ value }: { value: number }) {
  const text = value.toLocaleString("en-US");
  return (
    <span aria-hidden="true" className="inline-flex tabular-nums">
      {text.split("").map((char, i) => {
        // Keyed from the right, so the ones stay the ones when a digit is added.
        const key = text.length - i;
        if (char < "0" || char > "9") {
          return <span key={key}>{char}</span>;
        }
        const digit = Number(char);
        return (
          <span className="relative inline-block h-5 overflow-hidden" key={key}>
            <span
              className="flex flex-col transition-transform duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none"
              style={{ transform: `translateY(${-digit * 10}%)` }}
            >
              {"0123456789".split("").map((d) => (
                <span className="h-5 leading-5" key={d}>
                  {d}
                </span>
              ))}
            </span>
          </span>
        );
      })}
    </span>
  );
}

export interface BellButtonProps {
  /** `default` shows the label and count, `compact` the label, `icon` the bell alone. */
  variant?: "default" | "compact" | "icon";
  /** Controlled state. */
  subscribed?: boolean;
  defaultSubscribed?: boolean;
  onSubscribedChange?: (subscribed: boolean) => void;
  /** Subscribers, not counting this one. */
  count?: number;
  label?: string;
  subscribedLabel?: string;
  className?: string;
}

export default function BellButton({
  variant = "default",
  subscribed: subscribedProp,
  defaultSubscribed = false,
  onSubscribedChange,
  count = 1284,
  label = "Notify me",
  subscribedLabel = "Subscribed",
  className,
}: BellButtonProps) {
  const [internal, setInternal] = useState(defaultSubscribed);
  const subscribed = subscribedProp ?? internal;

  const bellRef = useRef<SVGGElement>(null);
  const clapperRef = useRef<SVGPathElement>(null);
  const leftWaveRef = useRef<SVGPathElement>(null);
  const rightWaveRef = useRef<SVGPathElement>(null);

  const sim = useRef({
    bell: 0,
    bellSpeed: 0,
    clapper: 0,
    clapperSpeed: 0,
    // Muffled: the clapper is held against the bell and can't strike.
    muffled: false,
    raf: 0,
    last: 0,
    carry: 0,
    lastNudge: 0,
    reduceMotion: false,
  });

  const draw = useCallback(() => {
    const s = sim.current;
    bellRef.current?.setAttribute(
      "transform",
      `rotate(${s.bell.toFixed(2)} ${PIVOT.x} ${PIVOT.y})`
    );
    clapperRef.current?.setAttribute(
      "transform",
      `rotate(${s.clapper.toFixed(2)} ${PIVOT.x} ${PIVOT.y})`
    );
  }, []);

  // Two short arcs flare out on the side that was struck.
  const flare = useCallback((side: 1 | -1, strength: number) => {
    const wave = side > 0 ? rightWaveRef.current : leftWaveRef.current;
    if (!wave?.animate) {
      return;
    }
    const peak = Math.min(1, 0.45 + strength * 0.55);
    wave.animate(
      [
        { opacity: peak, transform: "translateX(0px)" },
        { opacity: 0, transform: `translateX(${side * 3}px)` },
      ],
      { duration: 420, easing: EASE_OUT }
    );
  }, []);

  // Advances both pendulums one step and resolves a clapper hit.
  const step = useCallback(() => {
    const s = sim.current;
    s.bellSpeed +=
      (-s.bell * BELL_STIFFNESS - s.bellSpeed * BELL_DAMPING) * STEP;
    s.bell += s.bellSpeed * STEP;
    if (s.muffled) {
      s.clapper = s.bell;
      s.clapperSpeed = s.bellSpeed;
      return;
    }
    s.clapperSpeed +=
      (-s.clapper * CLAPPER_STIFFNESS - s.clapperSpeed * CLAPPER_DAMPING) *
      STEP;
    s.clapper += s.clapperSpeed * STEP;
    const relative = s.clapper - s.bell;
    if (Math.abs(relative) <= LIP) {
      return;
    }
    const side = relative > 0 ? 1 : -1;
    const impact = (s.clapperSpeed - s.bellSpeed) * side;
    s.clapper = s.bell + side * LIP;
    if (impact <= 0) {
      return;
    }
    s.clapperSpeed -= side * impact * (1 + RESTITUTION);
    s.bellSpeed += side * impact * RECOIL;
    if (impact > STRIKE_SPEED) {
      // The clapper hits the bell's right wall when it swings right.
      flare(side as 1 | -1, impact / 1600);
      haptic(6);
    }
  }, [flare]);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      s.carry += elapsed;
      while (s.carry >= STEP) {
        step();
        s.carry -= STEP;
      }
      draw();
      const energy =
        Math.abs(s.bell) +
        Math.abs(s.bellSpeed) * 0.02 +
        Math.abs(s.clapper) +
        Math.abs(s.clapperSpeed) * 0.02;
      if (energy < REST) {
        s.bell = 0;
        s.bellSpeed = 0;
        s.clapper = 0;
        s.clapperSpeed = 0;
        s.last = 0;
        draw();
        return;
      }
      s.raf = requestAnimationFrame(tick);
    },
    [draw, step]
  );

  const kick = useCallback(
    (speed: number) => {
      const s = sim.current;
      if (s.reduceMotion) {
        return;
      }
      s.bellSpeed += speed;
      if (!s.raf) {
        s.raf = requestAnimationFrame(tick);
      }
    },
    [tick]
  );

  useEffect(() => {
    const s = sim.current;
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = query.matches;
    const onChange = () => {
      s.reduceMotion = query.matches;
    };
    query.addEventListener("change", onChange);
    return () => {
      query.removeEventListener("change", onChange);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, []);

  const handleClick = () => {
    const next = !subscribed;
    if (subscribedProp === undefined) {
      setInternal(next);
    }
    onSubscribedChange?.(next);
    const s = sim.current;
    if (next) {
      s.muffled = false;
      // Swing the bell away from the clapper so the first hit rings.
      kick(s.bellSpeed >= 0 ? RING_KICK : -RING_KICK);
      if (s.reduceMotion) {
        flare(1, 0.6);
        flare(-1, 0.6);
      }
      haptic(10);
    } else {
      // Off: a dull shake, the clapper held still against the bell.
      s.muffled = true;
      kick(-MUTE_KICK);
    }
  };

  const handlePointerEnter = (event: PointerEvent) => {
    // A brush past the bell sets it swaying a little. Mouse only: on touch,
    // enter fires right before the tap.
    const s = sim.current;
    if (event.pointerType !== "mouse" || s.muffled) {
      return;
    }
    if (event.timeStamp - s.lastNudge < 700) {
      return;
    }
    s.lastNudge = event.timeStamp;
    kick(s.bellSpeed >= 0 ? NUDGE_KICK : -NUDGE_KICK);
  };

  // Starting unsubscribed means the bell is muted.
  useEffect(() => {
    sim.current.muffled = !subscribed;
  }, [subscribed]);

  return (
    <button
      aria-label={variant === "icon" ? label : undefined}
      aria-pressed={subscribed}
      className={cn(
        "inline-flex h-11 select-none items-center gap-2.5 rounded-full border font-medium text-sm outline-none transition-colors duration-200 ease-out focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 dark:ring-offset-zinc-950",
        variant === "default" && "pr-1.5 pl-4",
        variant === "compact" && "px-4",
        variant === "icon" && "w-11 justify-center",
        subscribed
          ? "border-zinc-900 bg-zinc-900 text-white hover:bg-zinc-800 active:bg-zinc-700 dark:border-zinc-100 dark:bg-zinc-100 dark:text-zinc-900 dark:active:bg-zinc-300 dark:hover:bg-zinc-200"
          : "border-zinc-200 bg-white text-zinc-900 hover:bg-zinc-50 active:bg-zinc-100 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100 dark:active:bg-zinc-800 dark:hover:bg-zinc-900",
        className
      )}
      onClick={handleClick}
      onPointerEnter={handlePointerEnter}
      type="button"
    >
      <svg
        aria-hidden="true"
        className="size-5 overflow-visible"
        fill="none"
        stroke="currentColor"
        strokeLinecap="round"
        strokeLinejoin="round"
        strokeWidth={2}
        viewBox="0 0 24 24"
      >
        <path
          className="opacity-0"
          d="M21.5 4.5c1.2 1.6 1.8 3.4 1.8 5.5"
          ref={rightWaveRef}
        />
        <path
          className="opacity-0"
          d="M2.5 4.5C1.3 6.1.7 7.9.7 10"
          ref={leftWaveRef}
        />
        <path d="M10.27 21a2 2 0 0 0 3.46 0" ref={clapperRef} />
        <g ref={bellRef}>
          <path
            className={cn(
              "transition-[fill] duration-200 ease-out",
              subscribed ? "fill-current" : "fill-transparent"
            )}
            d="M3.26 15.33A1 1 0 0 0 4 17h16a1 1 0 0 0 .74-1.67C19.41 13.96 18 12.5 18 8A6 6 0 0 0 6 8c0 4.5-1.41 5.96-2.74 7.33"
          />
          {/* The mute slash, drawn across when off. */}
          <path
            className="transition-[stroke-dashoffset] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none"
            d="M3 3l18 18"
            strokeDasharray="26"
            strokeDashoffset={subscribed ? 26 : 0}
          />
        </g>
      </svg>

      {variant === "icon" ? null : (
        <span className="relative grid">
          {[
            { key: "off", on: !subscribed, text: label },
            { key: "on", on: subscribed, text: subscribedLabel },
          ].map((line) => (
            <span
              aria-hidden={!line.on}
              className={cn(
                "col-start-1 row-start-1 whitespace-nowrap transition-[opacity,filter] duration-200 ease-out",
                line.on ? "opacity-100 blur-0" : "opacity-0 blur-[2px]"
              )}
              key={line.key}
            >
              {line.text}
            </span>
          ))}
        </span>
      )}

      {variant === "default" ? (
        <span
          className={cn(
            "rounded-full px-2.5 py-1 text-xs transition-colors duration-200 ease-out",
            subscribed
              ? "bg-white/15 text-white/80 dark:bg-zinc-900/10 dark:text-zinc-900/70"
              : "bg-zinc-100 text-zinc-500 dark:bg-zinc-900 dark:text-zinc-400"
          )}
        >
          <RollingNumber value={count + (subscribed ? 1 : 0)} />
          <span className="sr-only">
            {(count + (subscribed ? 1 : 0)).toLocaleString("en-US")} subscribers
          </span>
        </span>
      ) : null}
    </button>
  );
}
```


---

# Command Button
> Keyboard shortcut button with a Command icon, hover shimmer sweep, and smooth CSS transitions, built with React and Tailwind CSS.

Source: https://kokonutui.com/docs/buttons/command-button

## Installation

```bash
npx shadcn@latest add @kokonutui/command-button
```

## Source

```tsx
import { Command } from "lucide-react";
import type { ComponentProps } from "react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

/**
 * @author: @dorianbaffier
 * @description: Command Button
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

export default function CommandButton({
  className,
  children,
  ...props
}: ComponentProps<typeof Button>) {
  return (
    <Button
      {...props}
      className={cn(
        "relative p-2",
        "overflow-hidden rounded-lg",
        "bg-gradient-to-b from-zinc-50 to-zinc-100",
        "dark:from-zinc-800 dark:to-zinc-900",
        "border border-zinc-200 dark:border-zinc-800",
        "hover:border-zinc-300 dark:hover:border-zinc-700",
        "transition-[border-color,scale] duration-150 ease-out",
        "active:scale-[0.97] motion-reduce:active:scale-100",
        "group",
        className
      )}
    >
      <Command className="h-4 w-4 text-zinc-600 dark:text-zinc-400" />
      <span className="text-sm text-zinc-600 dark:text-zinc-400">
        {/* The icon already shows ⌘, so the default label is just the key. */}
        {children || (
          <kbd className="font-sans">
            <span className="sr-only">Command </span>K
          </kbd>
        )}
      </span>
      {/* Snaps back on leave instead of sweeping back across the label. */}
      <span
        aria-hidden="true"
        className={cn(
          "pointer-events-none absolute inset-0",
          "bg-gradient-to-r from-indigo-500/0 via-indigo-500/10 to-indigo-500/0",
          "translate-x-[-100%]",
          "group-hover:translate-x-[100%]",
          "group-hover:transition-transform group-hover:duration-300 group-hover:ease-out",
          "motion-reduce:hidden"
        )}
      />
    </Button>
  );
}
```


---

# Gradient Button
> Layered gradient button with emerald, purple, and orange variants, a gradient border in light and dark mode, soft inner glow, press feedback, and an optional icon, styled entirely with Tailwind CSS in React.

Source: https://kokonutui.com/docs/buttons/gradient-button

## Installation

```bash
npx shadcn@latest add @kokonutui/gradient-button
```

## Source

```tsx
/**
 * @author: @dorianbaffier
 * @description: Gradient Button
 * @version: 1.1.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import type { ComponentProps, ReactNode } from "react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

export type GradientButtonVariant = "emerald" | "purple" | "orange";

export interface GradientButtonProps
  extends Omit<ComponentProps<"button">, "children"> {
  /** Button content. Takes precedence over `label`. */
  children?: ReactNode;
  /** Fallback text when no `children` are passed. */
  label?: string;
  /** Optional icon rendered before the text (e.g. a lucide-react icon). */
  icon?: ReactNode;
  /** Color theme. */
  variant?: GradientButtonVariant;
}

interface VariantClasses {
  /** Focus ring color on the button itself. */
  ring: string;
  /** 2px gradient border (the button's own border-box background). */
  border: string;
  /** Solid surface under the color layers. */
  surface: string;
  /** Soft base tint, light mode only (dark mode shows the solid surface). */
  base: string;
  /** Vertical color wash. */
  overlay: string;
  /** Diagonal accent. */
  accent: string;
  /** Inset glow. */
  glow: string;
  /** Gradient text + dark-mode text glow. */
  text: string;
  /** Icon color. */
  icon: string;
  /** Hover sheen. */
  hover: string;
}

/**
 * Every class is a complete, static string so Tailwind can detect it at build
 * time. Light classes come first, dark ones are explicitly `dark:` prefixed.
 */
const variantClasses: Record<GradientButtonVariant, VariantClasses> = {
  emerald: {
    ring: "focus-visible:ring-emerald-500/60 dark:focus-visible:ring-[#87F6B7]/50",
    border:
      "from-emerald-400 via-emerald-300 to-emerald-200 dark:from-[#336C4F] dark:via-[#0C1F21] dark:to-[#0D6437]",
    surface: "dark:bg-[#0C1F21]",
    base: "from-emerald-50 via-emerald-50/80 to-emerald-50/90",
    overlay:
      "from-emerald-300/30 via-emerald-200/20 to-emerald-400/20 dark:from-[#347B52]/40 dark:via-[#0C1F21] dark:to-[#0D6437]/30",
    accent:
      "from-emerald-400/20 via-emerald-300/10 to-emerald-200/30 dark:from-[#87F6B7]/10 dark:via-[#0C1F21] dark:to-[#17362A]/50",
    glow: "shadow-[inset_0_0_10px_rgba(52,211,153,0.2)] dark:shadow-[inset_0_0_10px_rgba(135,246,183,0.1)]",
    text: "from-emerald-700 to-emerald-800 dark:from-[#8AEECA] dark:to-[#73F8A8] dark:drop-shadow-[0_0_12px_rgba(135,246,183,0.4)]",
    icon: "text-emerald-600 dark:text-[#73F8A8]",
    hover:
      "from-emerald-300/30 via-emerald-200/20 to-emerald-300/30 dark:from-[#17362A]/20 dark:via-[#87F6B7]/10 dark:to-[#17362A]/20",
  },
  purple: {
    ring: "focus-visible:ring-purple-500/60 dark:focus-visible:ring-[#D6BCFA]/50",
    border:
      "from-purple-400 via-purple-300 to-purple-200 dark:from-[#6B46C1] dark:via-[#150D21] dark:to-[#553C9A]",
    surface: "dark:bg-[#150D21]",
    base: "from-purple-50 via-purple-50/80 to-purple-50/90",
    overlay:
      "from-purple-300/30 via-purple-200/20 to-purple-400/20 dark:from-[#7E22CE]/40 dark:via-[#150D21] dark:to-[#6B46C1]/30",
    accent:
      "from-purple-400/20 via-purple-300/10 to-purple-200/30 dark:from-[#E9D8FD]/10 dark:via-[#150D21] dark:to-[#44337A]/50",
    glow: "shadow-[inset_0_0_10px_rgba(159,122,234,0.2)] dark:shadow-[inset_0_0_10px_rgba(159,122,234,0.1)]",
    text: "from-purple-700 to-purple-800 dark:from-[#E9D8FD] dark:to-[#D6BCFA] dark:drop-shadow-[0_0_12px_rgba(159,122,234,0.4)]",
    icon: "text-purple-600 dark:text-[#D6BCFA]",
    hover:
      "from-purple-300/30 via-purple-200/20 to-purple-300/30 dark:from-[#44337A]/20 dark:via-[#B794F4]/10 dark:to-[#44337A]/20",
  },
  orange: {
    ring: "focus-visible:ring-orange-500/60 dark:focus-visible:ring-[#FBD38D]/50",
    border:
      "from-orange-400 via-orange-300 to-orange-200 dark:from-[#C05621] dark:via-[#1F120A] dark:to-[#9C4221]",
    surface: "dark:bg-[#1F120A]",
    base: "from-orange-50 via-orange-50/80 to-orange-50/90",
    overlay:
      "from-orange-300/30 via-orange-200/20 to-orange-400/20 dark:from-[#DD6B20]/40 dark:via-[#1F120A] dark:to-[#C05621]/30",
    accent:
      "from-orange-400/20 via-orange-300/10 to-orange-200/30 dark:from-[#FED7AA]/10 dark:via-[#1F120A] dark:to-[#7B341E]/50",
    glow: "shadow-[inset_0_0_10px_rgba(237,137,54,0.2)] dark:shadow-[inset_0_0_10px_rgba(237,137,54,0.1)]",
    text: "from-orange-700 to-orange-800 dark:from-[#FED7AA] dark:to-[#FBD38D] dark:drop-shadow-[0_0_12px_rgba(237,137,54,0.4)]",
    icon: "text-orange-600 dark:text-[#FBD38D]",
    hover:
      "from-orange-300/30 via-orange-200/20 to-orange-300/30 dark:from-[#7B341E]/20 dark:via-[#ED8936]/10 dark:to-[#7B341E]/20",
  },
};

/**
 * Shared classes for the decorative layers inside the 2px border. They fill
 * the padding box and the button's overflow-hidden clips them to its inner
 * curve, so any radius passed through className (rounded-full too) works.
 */
const innerLayer = "pointer-events-none absolute inset-0";

// bg-clip-text makes the text transparent, which would also hide element
// children drawn with currentColor (an svg, a <kbd>), so only plain text gets
// the gradient.
function isPlainText(node: ReactNode): boolean {
  if (typeof node === "string" || typeof node === "number") {
    return true;
  }
  return Array.isArray(node) && node.every(isPlainText);
}

export default function GradientButton({
  children,
  label = "Welcome",
  icon,
  className,
  variant = "emerald",
  ...props
}: GradientButtonProps) {
  const colors = variantClasses[variant];
  const content = children ?? label;

  return (
    <Button
      className={cn(
        "group relative h-12 overflow-hidden rounded-lg border-2 border-transparent bg-linear-to-b bg-origin-border px-3.5",
        colors.border,
        // Ghost variant adds a hover background; the layers below own the look.
        "hover:bg-transparent dark:hover:bg-transparent",
        // Press feedback: transform only, short strong ease-out.
        "transition-transform duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] active:scale-[0.97]",
        "motion-reduce:transition-none motion-reduce:active:scale-100",
        colors.ring,
        className
      )}
      variant="ghost"
      {...props}
    >
      {/* Surface */}
      <span
        aria-hidden="true"
        className={cn(innerLayer, "bg-white", colors.surface)}
      />
      <span
        aria-hidden="true"
        className={cn(
          innerLayer,
          "bg-linear-to-r opacity-90 dark:hidden",
          colors.base
        )}
      />
      <span
        aria-hidden="true"
        className={cn(innerLayer, "bg-linear-to-b opacity-80", colors.overlay)}
      />
      <span
        aria-hidden="true"
        className={cn(innerLayer, "bg-linear-to-br", colors.accent)}
      />
      <span aria-hidden="true" className={cn(innerLayer, colors.glow)} />

      {/* Hover sheen: opacity only. Tailwind v4 gates hover to (hover: hover) devices. */}
      <span
        aria-hidden="true"
        className={cn(
          innerLayer,
          "bg-linear-to-r opacity-0 transition-opacity duration-200 ease-out group-hover:opacity-100 motion-reduce:transition-none",
          colors.hover
        )}
      />

      <span className="relative flex items-center justify-center gap-2">
        {icon ? (
          <span
            aria-hidden="true"
            className={cn("flex shrink-0 items-center", colors.icon)}
          >
            {icon}
          </span>
        ) : null}
        {isPlainText(content) ? (
          <span
            className={cn(
              "bg-linear-to-b bg-clip-text font-light text-lg text-transparent tracking-tighter",
              colors.text
            )}
          >
            {content}
          </span>
        ) : (
          <span
            className={cn(
              "flex items-center gap-2 font-light text-lg tracking-tighter",
              colors.icon
            )}
          >
            {content}
          </span>
        )}
      </span>
    </Button>
  );
}
```


---

# Hold Button
> Press-and-hold confirmation button with an animated progress fill, configurable hold duration, and color variants, built with React and Motion.

Source: https://kokonutui.com/docs/buttons/hold-button

## Installation

```bash
npx shadcn@latest add @kokonutui/hold-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Hold Button
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { cva, type VariantProps } from "class-variance-authority";
import {
  AlertCircleIcon,
  ArchiveXIcon,
  BanIcon,
  Trash2Icon,
  XCircleIcon,
} from "lucide-react";
import { useEffect, useRef, useState } from "react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

const holdButtonVariants = cva("relative min-w-40 touch-none overflow-hidden", {
  variants: {
    variant: {
      red: [
        "bg-red-100 dark:bg-red-200",
        "hover:bg-red-100 dark:hover:bg-red-200",
        "text-red-800",
        "border border-red-200 dark:border-red-300",
      ],
      green: [
        "bg-green-100 dark:bg-green-200",
        "hover:bg-green-100 dark:hover:bg-green-200",
        "text-green-800",
        "border border-green-200 dark:border-green-300",
      ],
      blue: [
        "bg-blue-100 dark:bg-blue-200",
        "hover:bg-blue-100 dark:hover:bg-blue-200",
        "text-blue-800",
        "border border-blue-200 dark:border-blue-300",
      ],
      orange: [
        "bg-orange-100 dark:bg-orange-200",
        "hover:bg-orange-100 dark:hover:bg-orange-200",
        "text-orange-800",
        "border border-orange-200 dark:border-orange-300",
      ],
      grey: [
        "bg-gray-100 dark:bg-gray-200",
        "hover:bg-gray-100 dark:hover:bg-gray-200",
        "text-gray-800",
        "border border-gray-200 dark:border-gray-300",
      ],
    },
  },
  defaultVariants: {
    variant: "red",
  },
});

interface HoldButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement>,
    VariantProps<typeof holdButtonVariants> {
  holdDuration?: number;
  /**
   * Called once the button has been held for the full `holdDuration`.
   * A short click or an early release never calls it.
   */
  onHoldComplete?: () => void;
}

const HOLD_KEYS = new Set([" ", "Enter"]);

const VARIANT_ICONS = {
  red: Trash2Icon,
  green: ArchiveXIcon,
  blue: XCircleIcon,
  orange: AlertCircleIcon,
  grey: BanIcon,
} as const;

const holdFeedbackClassName = cn(
  "select-none [-webkit-touch-callout:none]",
  "transition-[color,background-color,border-color,scale] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)]",
  "active:scale-[0.97] motion-reduce:active:scale-100"
);

export default function HoldButton({
  className,
  variant = "red",
  holdDuration = 3000,
  onHoldComplete,
  children,
  type = "button",
  ...props
}: HoldButtonProps) {
  const [isHolding, setIsHolding] = useState(false);
  const [isComplete, setIsComplete] = useState(false);
  const holdingRef = useRef(false);
  const timerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const onHoldCompleteRef = useRef(onHoldComplete);

  useEffect(() => {
    onHoldCompleteRef.current = onHoldComplete;
  }, [onHoldComplete]);

  useEffect(
    () => () => {
      if (timerRef.current) {
        clearTimeout(timerRef.current);
      }
    },
    []
  );

  function handleHoldStart() {
    // Browsers still dispatch pointer events to disabled buttons.
    if (holdingRef.current || props.disabled) {
      return;
    }
    holdingRef.current = true;
    setIsHolding(true);
    timerRef.current = setTimeout(() => {
      timerRef.current = null;
      if (holdingRef.current) {
        setIsComplete(true);
        onHoldCompleteRef.current?.();
      }
    }, holdDuration);
  }

  function handleHoldEnd() {
    if (!holdingRef.current) {
      return;
    }
    holdingRef.current = false;
    setIsHolding(false);
    setIsComplete(false);
    if (timerRef.current) {
      clearTimeout(timerRef.current);
      timerRef.current = null;
    }
  }

  function handlePointerDown(e: React.PointerEvent<HTMLButtonElement>) {
    props.onPointerDown?.(e);
    if (e.button !== 0) {
      return;
    }
    // Touch pointers are captured implicitly, which would keep the hold
    // going after the finger slides off. Release so pointerleave cancels it.
    if (e.currentTarget.hasPointerCapture(e.pointerId)) {
      e.currentTarget.releasePointerCapture(e.pointerId);
    }
    handleHoldStart();
  }

  const Icon = VARIANT_ICONS[variant ?? "red"];

  return (
    <Button
      {...props}
      className={cn(
        holdButtonVariants({ variant }),
        holdFeedbackClassName,
        className
      )}
      data-complete={isComplete || undefined}
      data-holding={isHolding || undefined}
      onBlur={(e) => {
        props.onBlur?.(e);
        handleHoldEnd();
      }}
      onKeyDown={(e) => {
        props.onKeyDown?.(e);
        if (!e.repeat && HOLD_KEYS.has(e.key)) {
          handleHoldStart();
        }
      }}
      onKeyUp={(e) => {
        props.onKeyUp?.(e);
        if (HOLD_KEYS.has(e.key)) {
          handleHoldEnd();
        }
      }}
      onPointerCancel={(e) => {
        props.onPointerCancel?.(e);
        handleHoldEnd();
      }}
      onPointerDown={handlePointerDown}
      onPointerLeave={(e) => {
        props.onPointerLeave?.(e);
        handleHoldEnd();
      }}
      onPointerUp={(e) => {
        props.onPointerUp?.(e);
        handleHoldEnd();
      }}
      type={type}
    >
      <span
        aria-hidden="true"
        className={cn(
          "pointer-events-none absolute inset-0 bg-current/15 transition-[clip-path] dark:bg-current/10",
          "motion-reduce:transition-opacity motion-reduce:[clip-path:none]",
          isHolding
            ? "ease-linear [clip-path:inset(0_0_0_0)] motion-reduce:opacity-100"
            : "duration-200 ease-[cubic-bezier(0.23,1,0.32,1)] [clip-path:inset(0_100%_0_0)] motion-reduce:opacity-0"
        )}
        style={
          isHolding ? { transitionDuration: `${holdDuration}ms` } : undefined
        }
      />
      <span className="relative z-10 flex w-full items-center justify-center gap-2">
        {children ?? (
          <>
            <Icon className="h-4 w-4" />
            {isHolding ? "Release" : "Hold me"}
          </>
        )}
      </span>
    </Button>
  );
}
```


---

# Particle Button
> Button that bursts animated particles from its center on click with a quick scale press effect, built with React, Motion, and Tailwind CSS.

Source: https://kokonutui.com/docs/buttons/particle-button

## Installation

```bash
npx shadcn@latest add @kokonutui/particle-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Particle Button
 * @version: 1.1.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { MousePointerClick } from "lucide-react";
import { motion, useReducedMotion } from "motion/react";
import {
  type ComponentProps,
  type MouseEvent,
  type ReactNode,
  useEffect,
  useRef,
  useState,
} from "react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

// `asChild` is left out: Slot needs a single child, and the button renders
// the particle layer, the label and the icon.
export interface ParticleButtonProps
  extends Omit<ComponentProps<typeof Button>, "asChild"> {
  /** Called after a click that was not `preventDefault()`-ed, alongside the burst. */
  onSuccess?: () => void;
  /** How long (ms) the particle layer stays mounted after a click. */
  successDuration?: number;
  /** Icon rendered after the label. Pass `null` to hide it. */
  icon?: ReactNode;
}

interface Particle {
  x: number;
  y: number;
}

interface Burst {
  id: number;
  particles: Particle[];
}

const PARTICLE_COUNT = 6;
const EASE_OUT = [0.23, 1, 0.32, 1] as const;

function createParticles(): Particle[] {
  return Array.from({ length: PARTICLE_COUNT }, (_, i) => ({
    x: (i % 2 ? 1 : -1) * (Math.random() * 40 + 16),
    y: -(Math.random() * 36 + 16),
  }));
}

function SuccessParticles({ particles }: { particles: Particle[] }) {
  return (
    <span
      aria-hidden="true"
      className="pointer-events-none absolute inset-0 overflow-visible"
    >
      {particles.map((particle, i) => (
        <motion.span
          animate={{
            opacity: [1, 1, 0],
            scale: [0.5, 1, 0.6],
            x: particle.x,
            y: particle.y,
          }}
          // Starts on the top edge: the dots share the button's color, so
          // any part of the path drawn over the button would be invisible.
          className="absolute top-0 left-1/2 -mt-0.5 -ml-0.5 size-1 rounded-full bg-zinc-900 dark:bg-zinc-50"
          initial={{ opacity: 0, scale: 0.5, x: 0, y: 0 }}
          // biome-ignore lint/suspicious/noArrayIndexKey: particles are a fixed-size, never-reordered list
          key={i}
          transition={{
            duration: 0.45,
            delay: i * 0.02,
            ease: EASE_OUT,
          }}
        />
      ))}
    </span>
  );
}

export default function ParticleButton({
  children,
  onClick,
  onSuccess,
  successDuration = 600,
  icon = <MousePointerClick className="h-4 w-4" />,
  className,
  ...props
}: ParticleButtonProps) {
  const [burst, setBurst] = useState<Burst | null>(null);
  const timeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);
  const burstIdRef = useRef(0);
  const shouldReduceMotion = useReducedMotion();

  useEffect(
    () => () => {
      if (timeoutRef.current) {
        clearTimeout(timeoutRef.current);
      }
    },
    []
  );

  const handleClick = (e: MouseEvent<HTMLButtonElement>) => {
    onClick?.(e);
    if (e.defaultPrevented) {
      return;
    }

    if (!shouldReduceMotion) {
      if (timeoutRef.current) {
        clearTimeout(timeoutRef.current);
      }
      burstIdRef.current += 1;
      // A new id remounts the particles so rapid re-clicks restart the burst.
      setBurst({ id: burstIdRef.current, particles: createParticles() });
      timeoutRef.current = setTimeout(() => {
        setBurst(null);
        timeoutRef.current = null;
      }, successDuration);
    }

    onSuccess?.();
  };

  // The particle layer sits inside the Button (absolute, so it skips the flex
  // gap) so `className` lands on the root and the burst paints above the face.
  return (
    <Button
      className={cn(
        "relative transition-[scale,background-color,color] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] active:scale-[0.97] motion-reduce:transition-none",
        className
      )}
      onClick={handleClick}
      {...props}
    >
      {burst && <SuccessParticles key={burst.id} particles={burst.particles} />}
      {children}
      {icon}
    </Button>
  );
}
```


---

# Pull Cord
> A lamp switch you pull on a swinging cord, built with React and a rope simulation.

Source: https://kokonutui.com/docs/buttons/pull-cord

## Installation

```bash
npx shadcn@latest add @kokonutui/pull-cord
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Pull Cord
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type PointerEvent,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

const WIDTH = 288;
const HEIGHT = 360;
// Where the cord hangs from, under the lamp shade.
const ANCHOR = { x: WIDTH / 2 + 36, y: 116 };
// The cord is a chain of points joined by fixed-length links.
const LINKS = 12;
const LINK = 8.5;
// Simulation, in px and seconds. A fixed step keeps the chain stable on any
// refresh rate.
const STEP = 1 / 120;
const GRAVITY = 1400;
const DAMPING = 0.992;
// Fastest a link may move in one step. Letting go of a stretched cord would
// otherwise fling it up into the shade.
const MAX_SPEED = 4;
// A cord has a little stiffness: two links apart, points never get closer
// than this, so it bends in curves instead of folding into kinks.
const BEND_MIN = LINK * 1.9;
const BEND_STIFFNESS = 0.8;
const ITERATIONS = 14;
// How far past its length the cord has to be pulled to click the switch,
// and how far it can stretch at all. The stretch flattens out, so it slows
// down instead of stopping at a wall.
const CLICK_PULL = 22;
const MAX_STRETCH = 34;
// Below this movement per step for a while, the chain is at rest and the
// loop stops.
const REST_EPSILON = 0.015;
const REST_STEPS = 24;

function damp(distance: number, max: number) {
  return max * (1 - Math.exp(-distance / max));
}

function haptic() {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(8);
  }
}

/**
 * Move points a and b towards `length` apart. A bend constraint only ever
 * pushes apart, and only part of the way each pass: stiff, not rigid.
 */
function relax(
  chain: { xs: Float64Array; ys: Float64Array; held: number },
  a: number,
  b: number,
  length: number,
  bend: boolean
) {
  const { xs, ys, held } = chain;
  const aFixed = a === 0 || a === held;
  const bFixed = b === held;
  if (aFixed && bFixed) {
    return;
  }
  const dx = xs[b] - xs[a];
  const dy = ys[b] - ys[a];
  const dist = Math.hypot(dx, dy) || 0.0001;
  if (bend && dist >= length) {
    return;
  }
  const diff = ((dist - length) / dist) * (bend ? BEND_STIFFNESS : 1);
  let wa = 0.5;
  if (aFixed) {
    wa = 0;
  } else if (bFixed) {
    wa = 1;
  }
  xs[a] += dx * diff * wa;
  ys[a] += dy * diff * wa;
  xs[b] -= dx * diff * (1 - wa);
  ys[b] -= dy * diff * (1 - wa);
}

/** A smooth curve through the chain's points. */
function cordPath(xs: Float64Array, ys: Float64Array) {
  let d = `M${xs[0].toFixed(2)} ${ys[0].toFixed(2)}`;
  for (let i = 1; i < xs.length - 1; i++) {
    const mx = (xs[i] + xs[i + 1]) / 2;
    const my = (ys[i] + ys[i + 1]) / 2;
    d += ` Q${xs[i].toFixed(2)} ${ys[i].toFixed(2)} ${mx.toFixed(2)} ${my.toFixed(2)}`;
  }
  const n = xs.length - 1;
  d += ` L${xs[n].toFixed(2)} ${ys[n].toFixed(2)}`;
  return d;
}

function restingChain() {
  const xs = new Float64Array(LINKS + 1);
  const ys = new Float64Array(LINKS + 1);
  for (let i = 0; i <= LINKS; i++) {
    xs[i] = ANCHOR.x;
    ys[i] = ANCHOR.y + i * LINK;
  }
  return { xs, ys };
}

const REST = restingChain();
const REST_PATH = cordPath(REST.xs, REST.ys);

export interface PullCordProps {
  /** Controlled state. */
  checked?: boolean;
  /** Initial state when uncontrolled. */
  defaultChecked?: boolean;
  onCheckedChange?: (checked: boolean) => void;
  /** Accessible name of the switch. */
  label?: string;
  className?: string;
}

export default function PullCord({
  checked: checkedProp,
  defaultChecked = true,
  onCheckedChange,
  label = "Desk lamp",
  className,
}: PullCordProps) {
  const [internal, setInternal] = useState(defaultChecked);
  const checked = checkedProp ?? internal;
  const [focused, setFocused] = useState(false);
  const [grabbing, setGrabbing] = useState(false);

  const svgRef = useRef<SVGSVGElement>(null);
  const cordRef = useRef<SVGPathElement>(null);
  const hitRef = useRef<SVGPathElement>(null);
  const beadRef = useRef<SVGGElement>(null);

  const sim = useRef({
    xs: Float64Array.from(REST.xs),
    ys: Float64Array.from(REST.ys),
    pxs: Float64Array.from(REST.xs),
    pys: Float64Array.from(REST.ys),
    raf: 0,
    last: 0,
    carry: 0,
    still: 0,
    // The link being held, and where the hand is holding it.
    held: -1,
    targetX: 0,
    targetY: 0,
    armed: true,
    reduceMotion: false,
  });

  // Read from pointer handlers, which outlive the render they came from.
  const latest = useRef<{ checked: boolean; toggle: (next: boolean) => void }>({
    checked,
    toggle: () => undefined,
  });
  const toggle = useCallback(
    (next: boolean) => {
      if (checkedProp === undefined) {
        setInternal(next);
      }
      onCheckedChange?.(next);
    },
    [checkedProp, onCheckedChange]
  );
  latest.current = { checked, toggle };

  const draw = useCallback(() => {
    const { xs, ys } = sim.current;
    const d = cordPath(xs, ys);
    cordRef.current?.setAttribute("d", d);
    hitRef.current?.setAttribute("d", d);
    const n = LINKS;
    const angle =
      (Math.atan2(xs[n] - xs[n - 1], ys[n] - ys[n - 1]) * 180) / Math.PI;
    beadRef.current?.setAttribute(
      "transform",
      `translate(${xs[n].toFixed(2)} ${ys[n].toFixed(2)}) rotate(${(-angle).toFixed(2)})`
    );
  }, []);

  // Verlet: each free link keeps the velocity it had last step, plus
  // gravity. The held link goes to the hand.
  const integrate = useCallback(() => {
    const s = sim.current;
    const { xs, ys, pxs, pys } = s;
    let moved = 0;
    for (let i = 1; i <= LINKS; i++) {
      if (i === s.held) {
        continue;
      }
      let vx = (xs[i] - pxs[i]) * DAMPING;
      let vy = (ys[i] - pys[i]) * DAMPING;
      const speed = Math.hypot(vx, vy);
      if (speed > MAX_SPEED) {
        vx *= MAX_SPEED / speed;
        vy *= MAX_SPEED / speed;
      }
      pxs[i] = xs[i];
      pys[i] = ys[i];
      xs[i] += vx;
      ys[i] += vy + GRAVITY * STEP * STEP;
      moved = Math.max(moved, Math.abs(vx) + Math.abs(vy));
    }
    if (s.held > 0) {
      const i = s.held;
      moved = Math.max(
        moved,
        Math.abs(s.targetX - xs[i]) + Math.abs(s.targetY - ys[i])
      );
      pxs[i] = xs[i];
      pys[i] = ys[i];
      xs[i] = s.targetX;
      ys[i] = s.targetY;
    }
    return moved;
  }, []);

  // Pull each link back to its length, and keep points two links apart from
  // folding too close. The anchor and the held link don't move; everything
  // else shares the correction.
  const constrain = useCallback(() => {
    const s = sim.current;
    for (let k = 0; k < ITERATIONS; k++) {
      for (let i = 0; i < LINKS; i++) {
        relax(s, i, i + 1, LINK, false);
      }
      for (let i = 0; i + 2 <= LINKS; i++) {
        relax(s, i, i + 2, BEND_MIN, true);
      }
    }
  }, []);

  const step = useCallback(() => {
    const moved = integrate();
    constrain();
    return moved;
  }, [integrate, constrain]);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      s.carry += elapsed;
      let moved = 0;
      while (s.carry >= STEP) {
        moved = Math.max(moved, step());
        s.carry -= STEP;
      }
      draw();
      s.still = moved < REST_EPSILON ? s.still + 1 : 0;
      if (s.held > 0 || s.still < REST_STEPS) {
        s.raf = requestAnimationFrame(tick);
      } else {
        s.last = 0;
      }
    },
    [draw, step]
  );

  const wake = useCallback(() => {
    const s = sim.current;
    s.still = 0;
    if (!s.raf) {
      s.raf = requestAnimationFrame(tick);
    }
  }, [tick]);

  useEffect(() => {
    const s = sim.current;
    s.reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    return () => cancelAnimationFrame(s.raf);
  }, []);

  const localPoint = (event: PointerEvent) => {
    const rect = svgRef.current?.getBoundingClientRect();
    if (!rect) {
      return { x: 0, y: 0 };
    }
    // The drawing is laid out in its own units; map the pointer into them.
    return {
      x: ((event.clientX - rect.left) / rect.width) * WIDTH,
      y: ((event.clientY - rect.top) / rect.height) * HEIGHT,
    };
  };

  // The hand can pull the cord a little past its length, with growing
  // resistance, but never pull it off the anchor.
  const reach = (index: number, x: number, y: number) => {
    const dx = x - ANCHOR.x;
    const dy = y - ANCHOR.y;
    const dist = Math.hypot(dx, dy) || 0.0001;
    const length = index * LINK;
    if (dist <= length) {
      return { x, y, pull: 0 };
    }
    const allowed = length + damp(dist - length, MAX_STRETCH);
    return {
      x: ANCHOR.x + (dx / dist) * allowed,
      y: ANCHOR.y + (dy / dist) * allowed,
      pull: dy > 0 ? (allowed - length) * (dy / dist) : 0,
    };
  };

  const handlePointerDown = (event: PointerEvent<SVGElement>) => {
    const s = sim.current;
    if (s.held > 0) {
      return;
    }
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    event.preventDefault();
    const point = localPoint(event);
    // Hold the link nearest to where the cord was grabbed.
    let nearest = LINKS;
    let best = Number.POSITIVE_INFINITY;
    for (let i = 1; i <= LINKS; i++) {
      const d = Math.hypot(s.xs[i] - point.x, s.ys[i] - point.y);
      if (d < best) {
        best = d;
        nearest = i;
      }
    }
    svgRef.current?.setPointerCapture(event.pointerId);
    s.held = nearest;
    s.targetX = s.xs[nearest];
    s.targetY = s.ys[nearest];
    s.armed = true;
    setGrabbing(true);
    wake();
  };

  const handlePointerMove = (event: PointerEvent<SVGSVGElement>) => {
    const s = sim.current;
    if (s.held < 0) {
      return;
    }
    const point = localPoint(event);
    const target = reach(s.held, point.x, point.y);
    s.targetX = target.x;
    s.targetY = target.y;
    // The switch clicks once per pull, as soon as the cord is pulled far
    // enough, not on release. It re-arms when the cord eases back.
    if (s.armed && target.pull > CLICK_PULL) {
      s.armed = false;
      haptic();
      latest.current.toggle(!latest.current.checked);
    } else if (!s.armed && target.pull < CLICK_PULL * 0.4) {
      s.armed = true;
    }
    wake();
  };

  const handlePointerUp = () => {
    const s = sim.current;
    if (s.held < 0) {
      return;
    }
    s.held = -1;
    setGrabbing(false);
    if (s.reduceMotion) {
      // No swinging back: the cord drops straight to rest.
      s.xs.set(REST.xs);
      s.ys.set(REST.ys);
      s.pxs.set(REST.xs);
      s.pys.set(REST.ys);
      draw();
      return;
    }
    wake();
  };

  const handleKeyToggle = () => {
    toggle(!checked);
    const s = sim.current;
    if (!s.reduceMotion) {
      // A small tug on the bead, so the cord answers the key too.
      s.pys[LINKS] = s.ys[LINKS] - 5;
      wake();
    }
  };

  return (
    <div
      className={cn(
        "relative select-none overflow-hidden rounded-3xl border transition-colors duration-300 ease-out",
        checked
          ? "border-zinc-200 bg-white text-zinc-900"
          : "border-zinc-800 bg-zinc-950 text-zinc-100",
        className
      )}
      style={{ width: WIDTH, height: HEIGHT }}
    >
      <svg
        aria-hidden="true"
        className={cn(
          "absolute inset-0 touch-none",
          grabbing ? "cursor-grabbing" : "cursor-default"
        )}
        height={HEIGHT}
        onLostPointerCapture={handlePointerUp}
        onPointerCancel={handlePointerUp}
        onPointerMove={handlePointerMove}
        onPointerUp={handlePointerUp}
        ref={svgRef}
        viewBox={`0 0 ${WIDTH} ${HEIGHT}`}
        width={WIDTH}
      >
        {/* Ceiling wire and shade. */}
        <line
          className={cn(
            "transition-[stroke] duration-300 ease-out",
            checked ? "stroke-zinc-300" : "stroke-zinc-700"
          )}
          strokeWidth={1.5}
          x1={WIDTH / 2}
          x2={WIDTH / 2}
          y1={0}
          y2={62}
        />
        <path
          className={cn(
            "transition-[fill] duration-300 ease-out",
            checked ? "fill-zinc-900" : "fill-zinc-800"
          )}
          d={`M${WIDTH / 2 - 14} 62 h28 l38 50 q2 4 -3 4 h-98 q-5 0 -3 -4 Z`}
        />
        {/* The bulb, lit or not. */}
        <path
          className={cn(
            "transition-[fill] duration-300 ease-out",
            checked ? "fill-amber-300" : "fill-zinc-700"
          )}
          d={`M${WIDTH / 2 - 15} 116 a15 13 0 0 0 30 0 Z`}
        />

        <path
          className={cn(
            "transition-[stroke] duration-300 ease-out",
            checked ? "stroke-zinc-400" : "stroke-zinc-600"
          )}
          d={REST_PATH}
          fill="none"
          ref={cordRef}
          strokeLinecap="round"
          strokeWidth={1.5}
        />
        {/* A wider invisible copy of the cord, so it's easy to grab. */}
        <path
          className={cn(!grabbing && "cursor-grab")}
          d={REST_PATH}
          fill="none"
          onPointerDown={handlePointerDown}
          pointerEvents="stroke"
          ref={hitRef}
          stroke="transparent"
          strokeWidth={22}
        />
        <g
          className={cn(!grabbing && "cursor-grab")}
          onPointerDown={handlePointerDown}
          ref={beadRef}
          transform={`translate(${ANCHOR.x} ${ANCHOR.y + LINKS * LINK})`}
        >
          <circle fill="transparent" r={20} />
          {focused && (
            <rect
              className="fill-none stroke-zinc-400"
              height={30}
              rx={9}
              strokeWidth={2}
              width={20}
              x={-10}
              y={-4}
            />
          )}
          <rect
            className={cn(
              "transition-[fill] duration-300 ease-out",
              checked ? "fill-zinc-800" : "fill-zinc-300"
            )}
            height={20}
            rx={5}
            width={10}
            x={-5}
            y={1}
          />
        </g>
      </svg>

      <div className="pointer-events-none absolute inset-x-0 bottom-0 p-6">
        <p className="font-medium text-sm">{label}</p>
        <p className="text-sm text-zinc-500">
          {checked ? "On" : "Off"} · pull the cord
        </p>
      </div>

      <button
        aria-checked={checked}
        aria-label={label}
        className="sr-only"
        onBlur={() => setFocused(false)}
        onClick={handleKeyToggle}
        onFocus={(event) =>
          setFocused(event.currentTarget.matches(":focus-visible"))
        }
        role="switch"
        type="button"
      />
    </div>
  );
}
```


---

# Slide Text Button
> Animated link button with a vertical text slide on hover and default and ghost variants, built with React, Next.js Link, and Tailwind CSS.

Source: https://kokonutui.com/docs/buttons/slide-text-button

## Installation

```bash
npx shadcn@latest add @kokonutui/slide-text-button
```

## Source

```tsx
"use client";

/**
 * @author: @kokonut-labs
 * @description: Slide Text Button with animated vertical text transition
 * @version: 1.0.0
 * @date: 2025-11-02
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import Link from "next/link";
import { cn } from "@/lib/utils";

interface SlideTextButtonProps
  extends React.AnchorHTMLAttributes<HTMLAnchorElement> {
  text?: string;
  hoverText?: string;
  href?: string;
  className?: string;
  variant?: "default" | "ghost";
  /** Fades and slides the button in when it mounts. */
  animateIn?: boolean;
}

export default function SlideTextButton({
  text = "Browse Components",
  hoverText,
  href = "/docs",
  className,
  variant = "default",
  animateIn = true,
  ...props
}: SlideTextButtonProps) {
  const slideText = hoverText ?? text;
  const variantStyles =
    variant === "ghost"
      ? "border border-black/10 text-black hover:bg-black/5 dark:border-white/10 dark:text-white dark:hover:bg-white/5"
      : "bg-black text-white hover:bg-black/90 dark:bg-white dark:text-black dark:hover:bg-white/90";

  return (
    <Link
      className={cn(
        "group relative inline-flex h-10 items-center justify-center overflow-hidden rounded-lg px-8 font-medium text-base tracking-tighter transition-[background-color,scale,opacity,translate] duration-[150ms,150ms,200ms,200ms] ease-[cubic-bezier(0.23,1,0.32,1)] focus-visible:outline-2 focus-visible:outline-black focus-visible:outline-offset-2 active:scale-[0.97] motion-reduce:active:scale-100 md:min-w-56 dark:focus-visible:outline-white",
        // CSS entrance from @starting-style: no JS and no wrapper element.
        // Reduced motion keeps the fade and drops the slide.
        animateIn &&
          "starting:translate-x-2 starting:opacity-0 motion-reduce:starting:translate-x-0",
        variantStyles,
        className
      )}
      href={href}
      {...props}
    >
      {/* Both labels share one grid cell, so the wider one sets the width
          and both stay centred; the hover label waits one row below. */}
      <span className="grid justify-items-center transition-transform duration-200 ease-[cubic-bezier(0.77,0,0.175,1)] group-hover:-translate-y-full group-focus-visible:-translate-y-full motion-reduce:transition-none">
        <span className="col-start-1 row-start-1 flex items-center gap-2 opacity-100 transition-opacity duration-200 group-hover:opacity-0 group-focus-visible:opacity-0">
          <span className="font-medium">{text}</span>
        </span>
        <span
          aria-hidden="true"
          className="col-start-1 row-start-1 flex translate-y-full items-center gap-2 opacity-0 transition-opacity duration-200 group-hover:opacity-100 group-focus-visible:opacity-100"
        >
          <span className="font-medium">{slideText}</span>
        </span>
      </span>
    </Link>
  );
}
```


---

# Social Button
> Share button that expands into a row of social icon buttons with staggered Motion animations on hover, built with React and Tailwind CSS.

Source: https://kokonutui.com/docs/buttons/social-button

## Installation

```bash
npx shadcn@latest add @kokonutui/social-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Social Button
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { Link } from "lucide-react";
import { motion, useReducedMotion } from "motion/react";
import { useEffect, useRef, useState } from "react";
import { flushSync } from "react-dom";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

export interface ShareItem {
  icon: React.ComponentType<{ className?: string }>;
  label: string;
  /** Renders the item as a link (opened in a new tab). */
  href?: string;
  onClick?: () => void;
}

interface SocialButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement> {
  label?: string;
  /** Icon shown on the trigger next to the label. */
  icon?: React.ComponentType<{ className?: string }>;
  items?: ShareItem[];
  onShare?: (index: number, item: ShareItem) => void;
  className?: string;
}

// lucide-react 1.x removed its brand icons, so the defaults ship inline
// (same paths as the old lucide Twitter, Instagram and Linkedin icons).
function TwitterIcon({ className }: { className?: string }) {
  return (
    <svg
      aria-hidden="true"
      className={className}
      fill="none"
      stroke="currentColor"
      strokeLinecap="round"
      strokeLinejoin="round"
      strokeWidth={2}
      viewBox="0 0 24 24"
    >
      <path d="M22 4s-.7 2.1-2 3.4c1.6 10-9.4 17.3-18 11.6 2.2.1 4.4-.6 6-2C3 15.5.5 9.6 3 5c2.2 2.6 5.6 4.1 9 4-.9-4.2 4-6.6 7-3.8 1.1 0 3-1.2 3-1.2z" />
    </svg>
  );
}

function InstagramIcon({ className }: { className?: string }) {
  return (
    <svg
      aria-hidden="true"
      className={className}
      fill="none"
      stroke="currentColor"
      strokeLinecap="round"
      strokeLinejoin="round"
      strokeWidth={2}
      viewBox="0 0 24 24"
    >
      <rect height="20" rx="5" ry="5" width="20" x="2" y="2" />
      <path d="M16 11.37A4 4 0 1 1 12.63 8 4 4 0 0 1 16 11.37z" />
      <line x1="17.5" x2="17.51" y1="6.5" y2="6.5" />
    </svg>
  );
}

function LinkedinIcon({ className }: { className?: string }) {
  return (
    <svg
      aria-hidden="true"
      className={className}
      fill="none"
      stroke="currentColor"
      strokeLinecap="round"
      strokeLinejoin="round"
      strokeWidth={2}
      viewBox="0 0 24 24"
    >
      <path d="M16 8a6 6 0 0 1 6 6v7h-4v-7a2 2 0 0 0-2-2 2 2 0 0 0-2 2v7h-4v-7a6 6 0 0 1 6-6z" />
      <rect height="12" width="4" x="2" y="9" />
      <circle cx="4" cy="4" r="2" />
    </svg>
  );
}

const DEFAULT_SHARE_ITEMS: ShareItem[] = [
  { icon: TwitterIcon, label: "Share on Twitter" },
  { icon: InstagramIcon, label: "Share on Instagram" },
  { icon: LinkedinIcon, label: "Share on LinkedIn" },
  {
    icon: Link,
    label: "Copy link",
    onClick: () => {
      navigator.clipboard?.writeText(window.location.href).catch(() => null);
    },
  },
];

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const HOVER_INTENT_MS = 100;

export default function SocialButton({
  label = "Share",
  icon: TriggerIcon = Link,
  items = DEFAULT_SHARE_ITEMS,
  onShare,
  className,
  onClick,
  onBlur,
  onKeyDown,
  ...props
}: SocialButtonProps) {
  const [isHovered, setIsHovered] = useState(false);
  // Opened by click/keyboard; stays open while focus is inside
  const [isOpen, setIsOpen] = useState(false);
  const isVisible = isHovered || isOpen;
  const [activeIndex, setActiveIndex] = useState<number | null>(null);
  const shouldReduceMotion = useReducedMotion();
  const rootRef = useRef<HTMLDivElement>(null);
  const rowRef = useRef<HTMLDivElement>(null);
  const triggerRef = useRef<HTMLButtonElement>(null);
  const pressTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
  const hoverTimer = useRef<ReturnType<typeof setTimeout> | null>(null);

  useEffect(
    () => () => {
      if (pressTimer.current) {
        clearTimeout(pressTimer.current);
      }
      if (hoverTimer.current) {
        clearTimeout(hoverTimer.current);
      }
    },
    []
  );

  const handleShare = (index: number) => {
    const item = items[index];
    setActiveIndex(index);
    item.onClick?.();
    onShare?.(index, item);
    if (pressTimer.current) {
      clearTimeout(pressTimer.current);
    }
    pressTimer.current = setTimeout(() => setActiveIndex(null), 300);
  };

  const handleTriggerClick = (e: React.MouseEvent<HTMLButtonElement>) => {
    onClick?.(e);
    if (e.defaultPrevented) {
      return;
    }
    // Commit the open state first so the items are no longer inert
    flushSync(() => setIsOpen(true));
    rowRef.current?.querySelector<HTMLElement>("a, button")?.focus();
  };

  // Mouse only: touch fires emulated mouse events that never "leave".
  const handlePointerEnter = (e: React.PointerEvent) => {
    if (e.pointerType !== "mouse") {
      return;
    }
    if (hoverTimer.current) {
      clearTimeout(hoverTimer.current);
    }
    hoverTimer.current = setTimeout(() => setIsHovered(true), HOVER_INTENT_MS);
  };

  const handlePointerLeave = (e: React.PointerEvent) => {
    if (e.pointerType !== "mouse") {
      return;
    }
    if (hoverTimer.current) {
      clearTimeout(hoverTimer.current);
    }
    setIsHovered(false);
  };

  // On the trigger and every item (not the wrapper), so the wrapper stays a
  // plain element.
  const handleBlur = (e: React.FocusEvent) => {
    if (!rootRef.current?.contains(e.relatedTarget)) {
      setIsOpen(false);
    }
  };

  const handleEscape = (e: React.KeyboardEvent) => {
    if (e.key === "Escape" && isVisible) {
      setIsOpen(false);
      setIsHovered(false);
      triggerRef.current?.focus();
    }
  };

  // Exits run faster than entrances.
  const revealDuration = isVisible ? 0.2 : 0.15;

  // `initial={false}` below renders the closed state in the server HTML.
  // Without it Motion leaves those styles out until hydration, so the share
  // row showed over the trigger and then animated shut on every page load.
  return (
    <div
      className="relative inline-flex"
      onPointerEnter={handlePointerEnter}
      onPointerLeave={handlePointerLeave}
      ref={rootRef}
    >
      <motion.div
        animate={{
          opacity: isVisible ? 0 : 1,
        }}
        initial={false}
        transition={{
          duration: 0.2,
          ease: EASE_OUT,
        }}
      >
        <Button
          className={cn(
            "relative min-w-40",
            "bg-white dark:bg-black",
            "hover:bg-gray-50 dark:hover:bg-gray-950",
            "text-black dark:text-white",
            "border border-black/10 dark:border-white/10",
            "transition-[color,background-color,border-color,scale] duration-200",
            "motion-safe:active:scale-[0.97]",
            className
          )}
          {...props}
          aria-expanded={isVisible}
          onBlur={(e) => {
            onBlur?.(e);
            handleBlur(e);
          }}
          onClick={handleTriggerClick}
          onKeyDown={(e) => {
            onKeyDown?.(e);
            handleEscape(e);
          }}
          ref={triggerRef}
          // Hidden under the open menu, so keep it out of the tab order
          tabIndex={isVisible ? -1 : props.tabIndex}
        >
          <span className="flex items-center gap-2">
            <TriggerIcon className="h-4 w-4" />
            {label}
          </span>
        </Button>
      </motion.div>

      {/* Covers the trigger exactly, one equal column per item */}
      <motion.div
        animate={{
          clipPath: isVisible ? "inset(0% 0% 0% 0%)" : "inset(0% 100% 0% 0%)",
        }}
        className="absolute inset-0 grid"
        inert={!isVisible}
        initial={false}
        ref={rowRef}
        style={{
          gridTemplateColumns: `repeat(${items.length}, minmax(0, 1fr))`,
        }}
        transition={{
          duration: shouldReduceMotion ? 0 : revealDuration,
          ease: EASE_OUT,
        }}
      >
        {items.map((item, i) => {
          const itemProps = {
            animate: {
              opacity: isVisible ? 1 : 0,
              x: isVisible ? 0 : -20,
            },
            "aria-label": item.label,
            initial: false,
            className: cn(
              "h-full w-full",
              "flex items-center justify-center",
              // Reduced motion: fade the items in without the slide.
              "motion-reduce:transform-none!",
              "bg-black dark:bg-white",
              "text-white dark:text-black",
              i === 0 && "rounded-l-md",
              i === items.length - 1 && "rounded-r-md",
              "border-white/10 border-r last:border-r-0 dark:border-black/10",
              "hover:bg-gray-900 dark:hover:bg-gray-100",
              "outline-hidden focus-visible:ring-2 focus-visible:ring-white/70 focus-visible:ring-inset dark:focus-visible:ring-black/70",
              "relative overflow-hidden",
              "transition-colors duration-200"
            ),
            onBlur: handleBlur,
            onClick: () => handleShare(i),
            onKeyDown: handleEscape,
            transition: {
              duration: revealDuration,
              ease: EASE_OUT,
              delay: isVisible ? i * 0.05 : 0,
            },
          };
          const content = (
            <>
              <motion.span
                animate={{
                  scale: activeIndex === i ? 0.95 : 1,
                }}
                className="motion-reduce:transform-none! relative z-10 inline-flex"
                initial={false}
                transition={{
                  duration: 0.2,
                  ease: EASE_OUT,
                }}
              >
                <item.icon className="h-4 w-4" />
              </motion.span>
              <motion.span
                animate={{
                  opacity: activeIndex === i ? 0.15 : 0,
                }}
                className="absolute inset-0 bg-white dark:bg-black"
                initial={{ opacity: 0 }}
                transition={{
                  duration: 0.2,
                  ease: EASE_OUT,
                }}
              />
            </>
          );
          return item.href ? (
            <motion.a
              {...itemProps}
              href={item.href}
              key={`share-${item.label}`}
              rel="noopener noreferrer"
              target="_blank"
            >
              {content}
            </motion.a>
          ) : (
            <motion.button
              {...itemProps}
              key={`share-${item.label}`}
              type="button"
            >
              {content}
            </motion.button>
          );
        })}
      </motion.div>
    </div>
  );
}
```


---

# Switch Button
> Light and dark theme toggle button with a rotating sun icon and shimmer hover effect, built with React and Tailwind CSS. Works on its own or with a theme provider such as next-themes.

Source: https://kokonutui.com/docs/buttons/switch-button

## Installation

```bash
npx shadcn@latest add @kokonutui/switch-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Switch Button
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 *
 * Works on its own: it toggles the `dark` class on <html>. If a theme provider
 * owns the theme (next-themes or your own), pass `theme` and `onThemeChange`.
 */

import { Moon, Sun } from "lucide-react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

type Theme = "light" | "dark";

interface SwitchButtonProps
  extends React.ButtonHTMLAttributes<HTMLButtonElement> {
  variant?: "minimal";
  size?: "sm" | "default" | "lg";
  showLabel?: boolean;
  /**
   * The applied theme, when a theme provider owns it (for next-themes, its
   * `resolvedTheme`). Pair it with `onThemeChange`. Without it the button
   * toggles the `dark` class on <html> itself.
   */
  theme?: Theme;
  /** Called with the theme to switch to. */
  onThemeChange?: (theme: Theme) => void;
}

const VARIANTS = {
  minimal: [
    "rounded-lg",
    "bg-linear-to-b from-zinc-50 to-zinc-100 dark:from-zinc-800 dark:to-zinc-900",
    "hover:from-zinc-100 hover:to-zinc-200 dark:hover:from-zinc-700 dark:hover:to-zinc-800",
    "border border-zinc-200 dark:border-zinc-700/80",
    "hover:border-zinc-300 dark:hover:border-zinc-600",
    "shadow-[0_1px_2px_-1px_rgb(0_0_0/0.1),0_1px_3px_-2px_rgb(0_0_0/0.1)] dark:shadow-[0_1px_2px_-1px_rgb(0_0_0/0.3),0_1px_3px_-2px_rgb(0_0_0/0.3)]",
    "hover:shadow-[0_2px_4px_-2px_rgb(0_0_0/0.15),0_2px_6px_-3px_rgb(0_0_0/0.15)] dark:hover:shadow-[0_2px_4px_-2px_rgb(0_0_0/0.4),0_2px_6px_-3px_rgb(0_0_0/0.4)]",
    "active:shadow-[0_0px_1px_0_rgb(0_0_0/0.1)] dark:active:shadow-[0_0px_1px_0_rgb(0_0_0/0.2)]",
    "transition-[color,background-color,border-color,box-shadow,scale,--tw-gradient-from,--tw-gradient-to] duration-200 ease-out",
    "motion-safe:active:scale-[0.97]",
  ],
};

// The base Button sizes every svg with `[&_svg]:size-4`, which beats a class
// on the icon itself, so the icon size is set from the button.
const SIZES = {
  sm: "h-8 px-3 text-sm [&_svg]:size-3.5",
  default: "h-10 px-4",
  lg: "h-11 px-5 [&_svg]:size-5",
};

const ICON_TRANSITION =
  "transition-[opacity,rotate,scale,color] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-[opacity,color]";

export default function SwitchButton({
  className,
  variant = "minimal",
  size = "default",
  showLabel = true,
  theme,
  onThemeChange,
  onClick,
  ...props
}: SwitchButtonProps) {
  const handleClick = (e: React.MouseEvent<HTMLButtonElement>) => {
    onClick?.(e);
    if (e.defaultPrevented) {
      return;
    }
    const root = document.documentElement;
    const current =
      theme ?? (root.classList.contains("dark") ? "dark" : "light");
    const next = current === "dark" ? "light" : "dark";
    if (theme === undefined) {
      root.classList.toggle("dark", next === "dark");
      root.style.colorScheme = next;
    }
    onThemeChange?.(next);
  };

  // The theme is unknown during SSR, so the light/dark look below is driven by
  // `dark:` classes instead of branching on the theme while rendering.
  return (
    <Button
      aria-label="Toggle theme"
      className={cn(
        "group relative",
        "text-zinc-600 dark:text-zinc-300",
        "hover:text-zinc-800 dark:hover:text-zinc-100",
        VARIANTS[variant],
        SIZES[size],
        className
      )}
      variant="ghost"
      {...props}
      onClick={handleClick}
    >
      <span className="flex items-center gap-2">
        <span className="relative inline-flex">
          <Sun
            className={cn(
              ICON_TRANSITION,
              "rotate-0 group-hover:rotate-[360deg] group-hover:scale-110",
              "drop-shadow-[0_0_12px_rgba(252,211,77,0.3)]",
              "text-amber-500 group-hover:text-amber-600",
              "dark:rotate-90 dark:scale-90 dark:opacity-0"
            )}
          />
          <Moon
            className={cn(
              ICON_TRANSITION,
              "absolute inset-0",
              "-rotate-90 scale-90 opacity-0",
              "dark:rotate-0 dark:scale-100 dark:opacity-100",
              "dark:group-hover:-rotate-12 dark:group-hover:scale-110"
            )}
          />
        </span>
        {showLabel && (
          <span aria-hidden="true" className="relative font-medium capitalize">
            <span
              className={cn(
                "absolute inset-0",
                "opacity-100 dark:opacity-0",
                "transition-opacity duration-300 ease-out"
              )}
            >
              Light
              <span
                className={cn(
                  "absolute -bottom-px left-0 h-px w-full",
                  "bg-linear-to-r from-zinc-400/0 via-zinc-400/50 to-zinc-400/0",
                  "dark:from-zinc-600/0 dark:via-zinc-600/50 dark:to-zinc-600/0",
                  "opacity-0 group-hover:opacity-100",
                  "transition-opacity duration-200"
                )}
              />
            </span>
            <span
              className={cn(
                "absolute inset-0",
                "opacity-0 dark:opacity-100",
                "transition-opacity duration-300 ease-out"
              )}
            >
              Dark
              <span
                className={cn(
                  "absolute -bottom-px left-0 h-px w-full",
                  "bg-linear-to-r from-zinc-400/0 via-zinc-400/50 to-zinc-400/0",
                  "dark:from-zinc-600/0 dark:via-zinc-600/50 dark:to-zinc-600/0",
                  "opacity-0 group-hover:opacity-100",
                  "transition-opacity duration-200"
                )}
              />
            </span>
            <span className="opacity-0">Light</span>
          </span>
        )}
      </span>
    </Button>
  );
}
```

## Usage

With no props, the button toggles the `dark` class on `<html>`, which is what Tailwind's class-based `dark:` variant reads. It does not save the choice.

If a theme provider already owns the theme, pass the applied theme and a setter instead. With next-themes:

```tsx
"use client";

import { useTheme } from "next-themes";
import SwitchButton from "@/components/kokonutui/switch-button";

export function ThemeSwitch() {
  const { resolvedTheme, setTheme } = useTheme();

  return (
    <SwitchButton
      onThemeChange={setTheme}
      theme={resolvedTheme === "dark" ? "dark" : "light"}
    />
  );
}
```

| Prop            | Type                                 | Default     | Description                                                                                        |
| --------------- | ------------------------------------ | ----------- | -------------------------------------------------------------------------------------------------- |
| `theme`         | `"light" \| "dark"`                  | —           | The applied theme, when a provider owns it. Without it the button toggles the `dark` class itself. |
| `onThemeChange` | `(theme: "light" \| "dark") => void` | —           | Called with the theme to switch to.                                                                |
| `size`          | `"sm" \| "default" \| "lg"`          | `"default"` | Button size.                                                                                       |
| `showLabel`     | `boolean`                            | `true`      | Shows "Light" or "Dark" next to the icon.                                                          |


---

# Tear Button
> A confirm button you tear off like a ticket stub, hole by hole.

Source: https://kokonutui.com/docs/buttons/tear-button

## Installation

```bash
npx shadcn@latest add @kokonutui/tear-button
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Tear Button
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

const HEIGHT = 68;
const BODY_WIDTH = 236;
const STUB_WIDTH = 76;
// How far (deg) the stub swings, about the foot of the perforation, before
// the last fibre gives.
const TEAR_ANGLE = 34;
// The perforation tears hole by hole: each one holds for a moment, then
// gives. That stick-slip is what makes it feel like paper.
const HOLES = 7;
const HOLD = 0.55;
const HOLD_SHARE = 0.3;
// The stub's swing chases the hand on a stiff spring, so the slips snap.
const SWING_STIFFNESS = 900;
const SWING_DAMPING = 42;
const RETURN_STIFFNESS = 520;
const RETURN_DAMPING = 22;
// Once free: px and seconds.
const GRAVITY = 2600;
const FALL_DISTANCE = 220;
const STEP = 1 / 120;
// Ragged edge of the tear, as offsets in px along the perforation.
const FIBRES = [
  1.6, 0.4, 2.2, 0.9, 1.8, 0.2, 2.4, 1.1, 0.5, 2, 1.4, 0.3, 2.3, 0.8, 1.7, 0.1,
  2.1, 1.2, 0.6, 1.9,
];
const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";

type Phase = "idle" | "tearing" | "flying" | "torn";

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), max);
}

function haptic(ms: number) {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(ms);
  }
}

/** Raw pull (0..1+) to how far the tear has run, holding at each hole. */
function stickSlip(pull: number) {
  const scaled = clamp(pull, 0, 1) * HOLES;
  const hole = Math.min(Math.floor(scaled), HOLES - 1);
  const f = scaled - hole;
  const given =
    f < HOLD
      ? (f / HOLD) * HOLD_SHARE
      : HOLD_SHARE + ((f - HOLD) / (1 - HOLD)) * (1 - HOLD_SHARE);
  return (hole + given) / HOLES;
}

/**
 * One side of the tear as a clip-path: ragged down to `tip` (px from the
 * top), straight below. `side` is 1 for the body's right edge, -1 for the
 * stub's left edge.
 */
function tornEdge(tip: number, width: number, side: 1 | -1) {
  const points: string[] = [];
  const edge = side === 1 ? width : 0;
  const far = side === 1 ? 0 : width;
  points.push(`${far}px 0px`);
  const rows = Math.ceil((tip / HEIGHT) * FIBRES.length);
  for (let k = 0; k <= rows; k++) {
    const y = Math.min((k / FIBRES.length) * HEIGHT, tip);
    const x = edge - side * FIBRES[k % FIBRES.length];
    points.push(`${x.toFixed(1)}px ${y.toFixed(1)}px`);
  }
  points.push(`${edge}px ${tip.toFixed(1)}px`, `${edge}px ${HEIGHT}px`);
  points.push(`${far}px ${HEIGHT}px`);
  return `polygon(${points.join(",")})`;
}

// Ticket notches, cut where the perforation meets the top and bottom edges.
const NOTCH = 7;
const bodyMask = `radial-gradient(circle at 100% 0, #0000 ${NOTCH}px, #000 ${NOTCH + 0.5}px) top / 100% 51% no-repeat, radial-gradient(circle at 100% 100%, #0000 ${NOTCH}px, #000 ${NOTCH + 0.5}px) bottom / 100% 51% no-repeat`;
const stubMask = `radial-gradient(circle at 0 0, #0000 ${NOTCH}px, #000 ${NOTCH + 0.5}px) top / 100% 51% no-repeat, radial-gradient(circle at 0 100%, #0000 ${NOTCH}px, #000 ${NOTCH + 0.5}px) bottom / 100% 51% no-repeat`;

const TONES = {
  default: {
    paper: "bg-zinc-900 text-white dark:bg-zinc-100 dark:text-zinc-900",
    chip: "bg-white/10 dark:bg-zinc-900/10",
    chipDone: "bg-white text-zinc-900 dark:bg-zinc-900 dark:text-white",
    sub: "text-white/55 dark:text-zinc-900/55",
    stub: "text-white/60 dark:text-zinc-900/60",
    perforation: "border-white/30 dark:border-zinc-900/30",
  },
  muted: {
    paper: "bg-zinc-100 text-zinc-900 dark:bg-zinc-800 dark:text-zinc-100",
    chip: "bg-zinc-900/5 dark:bg-white/10",
    chipDone: "bg-zinc-900 text-white dark:bg-white dark:text-zinc-900",
    sub: "text-zinc-500 dark:text-zinc-400",
    stub: "text-zinc-500 dark:text-zinc-400",
    perforation: "border-zinc-900/20 dark:border-white/25",
  },
  danger: {
    paper: "bg-red-600 text-white",
    chip: "bg-white/15",
    chipDone: "bg-white text-red-600",
    sub: "text-white/70",
    stub: "text-white/75",
    perforation: "border-white/40",
  },
} as const;

const TRASH = (
  <svg
    aria-hidden="true"
    className="size-4"
    fill="none"
    stroke="currentColor"
    strokeLinecap="round"
    strokeLinejoin="round"
    strokeWidth={2}
    viewBox="0 0 24 24"
  >
    <path d="M4 7h16M10 11v6M14 11v6M6 7l1 12a2 2 0 0 0 2 2h6a2 2 0 0 0 2-2l1-12M9 7V4h6v3" />
  </svg>
);

export interface TearButtonProps {
  /** Paper colour. */
  tone?: keyof typeof TONES;
  /** Shown in the round chip until the stub is torn; a trash can by default. */
  icon?: ReactNode;
  label?: string;
  description?: string;
  stubLabel?: string;
  confirmedLabel?: string;
  confirmedDescription?: string;
  /** Called once the stub comes away. */
  onConfirm?: () => void;
  /** Print a fresh stub this many ms after confirming. Off when 0. */
  resetAfter?: number;
  className?: string;
}

export default function TearButton({
  tone = "default",
  icon = TRASH,
  label = "Delete workspace",
  description = "Tear off the stub to confirm",
  stubLabel = "Tear",
  confirmedLabel = "Workspace deleted",
  confirmedDescription = "Kept in trash for 30 days",
  onConfirm,
  resetAfter = 2400,
  className,
}: TearButtonProps) {
  const [phase, setPhase] = useState<Phase>("idle");
  const [generation, setGeneration] = useState(0);
  const rootRef = useRef<HTMLDivElement>(null);
  const bodyRef = useRef<HTMLDivElement>(null);
  const stubRef = useRef<HTMLButtonElement>(null);

  const sim = useRef({
    angle: 0,
    speed: 0,
    target: 0,
    held: false,
    grabAngle: 0,
    hole: 0,
    raf: 0,
    last: 0,
    carry: 0,
    // Free flight, once torn.
    x: 0,
    y: 0,
    vx: 0,
    vy: 0,
    spin: 0,
    // The hand's recent movement, for the throw.
    px: 0,
    py: 0,
    pt: 0,
    pvx: 0,
    pvy: 0,
    auto: 0,
    flying: false,
    reduceMotion: false,
  });

  const latest = useRef({ onConfirm });
  latest.current = { onConfirm };

  const hinge = useCallback(() => {
    const rect = rootRef.current?.getBoundingClientRect();
    return rect
      ? { x: rect.left + BODY_WIDTH, y: rect.top + HEIGHT }
      : { x: 0, y: 0 };
  }, []);

  const drawTear = useCallback(() => {
    const s = sim.current;
    const tip = clamp(s.angle / TEAR_ANGLE, 0, 1) * HEIGHT;
    const stub = stubRef.current;
    const body = bodyRef.current;
    if (body) {
      body.style.clipPath = tip > 0.5 ? tornEdge(tip, BODY_WIDTH, 1) : "";
    }
    if (stub) {
      stub.style.clipPath = tip > 0.5 ? tornEdge(tip, STUB_WIDTH, -1) : "";
      stub.style.transform = `rotate(${s.angle.toFixed(2)}deg)`;
    }
  }, []);

  const drawFlight = useCallback(() => {
    const s = sim.current;
    const stub = stubRef.current;
    if (!stub) {
      return;
    }
    const fade = clamp(
      1 - (s.y - FALL_DISTANCE * 0.5) / (FALL_DISTANCE * 0.5),
      0,
      1
    );
    stub.style.transform = `translate(${s.x.toFixed(1)}px, ${s.y.toFixed(1)}px) rotate(${s.angle.toFixed(1)}deg)`;
    stub.style.opacity = fade.toFixed(3);
  }, []);

  const detach = useCallback(() => {
    const s = sim.current;
    s.held = false;
    haptic(14);
    // The stub leaves with the swing it had, plus the hand's throw.
    const rad = (s.angle * Math.PI) / 180;
    const tangential = ((s.speed * Math.PI) / 180) * HEIGHT;
    s.x = 0;
    s.y = 0;
    s.vx = Math.cos(rad) * tangential + clamp(s.pvx, -900, 900) * 0.6 + 90;
    s.vy = Math.sin(rad) * tangential + clamp(s.pvy, -900, 900) * 0.6 - 120;
    s.spin = s.speed * 0.6 + 140;
    s.flying = true;
    if (stubRef.current) {
      stubRef.current.style.transition = "none";
    }
    setPhase("flying");
    latest.current.onConfirm?.();
  }, []);

  // While attached: the swing chases its target, held or springing home.
  const stepSwing = useCallback(() => {
    const s = sim.current;
    const stiffness = s.held || s.auto ? SWING_STIFFNESS : RETURN_STIFFNESS;
    const damping = s.held || s.auto ? SWING_DAMPING : RETURN_DAMPING;
    const force = (s.target - s.angle) * stiffness - s.speed * damping;
    s.speed += force * STEP;
    s.angle += s.speed * STEP;
    // A tick for each hole that gives.
    const hole = Math.floor(clamp(s.angle / TEAR_ANGLE, 0, 1) * HOLES);
    if (hole > s.hole) {
      haptic(3);
    }
    s.hole = hole;
    return s.angle >= TEAR_ANGLE * 0.995;
  }, []);

  const stepFlight = useCallback(() => {
    const s = sim.current;
    s.vy += GRAVITY * STEP;
    s.x += s.vx * STEP;
    s.y += s.vy * STEP;
    s.angle += s.spin * STEP;
    return s.y > FALL_DISTANCE;
  }, []);

  // Runs the fixed steps owed since the last frame; true once this phase is
  // over (the stub tore through, or it has fallen out of sight).
  const advance = useCallback(
    (elapsed: number) => {
      const s = sim.current;
      s.carry += elapsed;
      let finished = false;
      while (s.carry >= STEP && !finished) {
        s.carry -= STEP;
        if (s.flying) {
          finished = stepFlight();
        } else if (s.auto) {
          s.target = Math.min(s.target + STEP * 60, TEAR_ANGLE * 1.05);
          finished = stepSwing();
        } else {
          finished = stepSwing() && s.held;
        }
      }
      return finished;
    },
    [stepFlight, stepSwing]
  );

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      const { flying } = s;
      const finished = advance(elapsed);
      if (flying) {
        drawFlight();
        if (finished) {
          s.last = 0;
          setPhase("torn");
          return;
        }
        s.raf = requestAnimationFrame(tick);
        return;
      }
      drawTear();
      if (finished) {
        s.auto = 0;
        detach();
        s.raf = requestAnimationFrame(tick);
        return;
      }
      const resting =
        !(s.held || s.auto) &&
        Math.abs(s.angle) < 0.02 &&
        Math.abs(s.speed) < 0.05;
      if (!resting) {
        s.raf = requestAnimationFrame(tick);
        return;
      }
      s.angle = 0;
      s.speed = 0;
      s.last = 0;
      drawTear();
      setPhase("idle");
    },
    [advance, detach, drawFlight, drawTear]
  );

  const wake = useCallback(() => {
    const s = sim.current;
    if (!s.raf) {
      s.raf = requestAnimationFrame(tick);
    }
  }, [tick]);

  useEffect(() => {
    const s = sim.current;
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = query.matches;
    const onChange = () => {
      s.reduceMotion = query.matches;
    };
    query.addEventListener("change", onChange);
    return () => {
      query.removeEventListener("change", onChange);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, []);

  // A fresh stub, a little while after the last one came away.
  useEffect(() => {
    if (phase !== "torn" || !resetAfter) {
      return;
    }
    const id = window.setTimeout(() => {
      const s = sim.current;
      s.angle = 0;
      s.speed = 0;
      s.target = 0;
      s.hole = 0;
      s.flying = false;
      setGeneration((g) => g + 1);
      setPhase("idle");
    }, resetAfter);
    return () => window.clearTimeout(id);
  }, [phase, resetAfter]);

  // In reduced motion the stub doesn't fall: it fades where it tore.
  useEffect(() => {
    if (phase !== "flying" || !sim.current.reduceMotion) {
      return;
    }
    const s = sim.current;
    cancelAnimationFrame(s.raf);
    s.raf = 0;
    s.last = 0;
    const stub = stubRef.current;
    if (stub) {
      stub.style.transition = `opacity 180ms ${EASE_OUT}`;
      stub.style.opacity = "0";
    }
    const id = window.setTimeout(() => setPhase("torn"), 180);
    return () => window.clearTimeout(id);
  }, [phase]);

  const handlePointerDown = (event: PointerEvent<HTMLButtonElement>) => {
    const s = sim.current;
    if (phase === "flying" || phase === "torn") {
      return;
    }
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    event.preventDefault();
    event.currentTarget.setPointerCapture(event.pointerId);
    const h = hinge();
    s.grabAngle =
      (Math.atan2(event.clientY - h.y, event.clientX - h.x) * 180) / Math.PI -
      s.angle;
    s.held = true;
    s.px = event.clientX;
    s.py = event.clientY;
    s.pt = event.timeStamp;
    s.pvx = 0;
    s.pvy = 0;
    setPhase("tearing");
    wake();
  };

  const handlePointerMove = (event: PointerEvent<HTMLButtonElement>) => {
    const s = sim.current;
    if (!s.held) {
      return;
    }
    const dt = event.timeStamp - s.pt;
    if (dt > 0) {
      s.pvx = s.pvx * 0.5 + ((event.clientX - s.px) / dt) * 500;
      s.pvy = s.pvy * 0.5 + ((event.clientY - s.py) / dt) * 500;
    }
    s.px = event.clientX;
    s.py = event.clientY;
    s.pt = event.timeStamp;
    const h = hinge();
    const raw =
      (Math.atan2(event.clientY - h.y, event.clientX - h.x) * 180) / Math.PI -
      s.grabAngle;
    // Pushing the stub back into the body only gives a little.
    const pull = raw < 0 ? raw * 0.15 : raw;
    s.target =
      pull >= TEAR_ANGLE
        ? TEAR_ANGLE * 1.05
        : stickSlip(Math.max(pull, 0) / TEAR_ANGLE) * TEAR_ANGLE +
          Math.min(pull, 0);
    wake();
  };

  const handlePointerUp = () => {
    const s = sim.current;
    if (!s.held) {
      return;
    }
    s.held = false;
    // Not torn through: the stub swings back and the perforation holds.
    s.target = 0;
    wake();
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLButtonElement>) => {
    if (event.key !== "Enter" && event.key !== " ") {
      return;
    }
    event.preventDefault();
    const s = sim.current;
    if (phase !== "idle" || event.repeat) {
      return;
    }
    // From the keyboard the stub tears itself, hole by hole.
    s.auto = 1;
    s.target = 0;
    setPhase("tearing");
    wake();
  };

  const done = phase === "flying" || phase === "torn";
  const colors = TONES[tone];

  return (
    <div
      className={cn("relative select-none", className)}
      ref={rootRef}
      style={{ width: BODY_WIDTH + STUB_WIDTH, height: HEIGHT }}
    >
      <div
        className={cn(
          "absolute inset-y-0 left-0 flex items-center gap-3 rounded-l-2xl px-4",
          colors.paper
        )}
        ref={bodyRef}
        style={{ width: BODY_WIDTH, mask: bodyMask, WebkitMask: bodyMask }}
      >
        <span
          aria-hidden="true"
          className={cn(
            "flex size-9 shrink-0 items-center justify-center rounded-full transition-colors duration-300 ease-out",
            done ? colors.chipDone : colors.chip
          )}
        >
          {done ? (
            <svg
              aria-hidden="true"
              className="size-4"
              fill="none"
              stroke="currentColor"
              strokeLinecap="round"
              strokeLinejoin="round"
              strokeWidth={2}
              viewBox="0 0 24 24"
            >
              <path d="M5 12.5l4.5 4.5L19 7.5" />
            </svg>
          ) : (
            icon
          )}
        </span>
        <span className="relative grid min-w-0 flex-1">
          {[
            { key: "ask", on: !done, title: label, sub: description },
            {
              key: "done",
              on: done,
              title: confirmedLabel,
              sub: confirmedDescription,
            },
          ].map((line) => (
            <span
              aria-hidden={!line.on}
              className={cn(
                "col-start-1 row-start-1 min-w-0 transition-[opacity,filter,translate] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-opacity",
                line.on
                  ? "translate-y-0 opacity-100 blur-0"
                  : "pointer-events-none translate-y-1 opacity-0 blur-[3px]"
              )}
              key={line.key}
            >
              <span className="block truncate font-medium text-sm">
                {line.title}
              </span>
              <span className={cn("block truncate text-xs", colors.sub)}>
                {line.sub}
              </span>
            </span>
          ))}
        </span>
      </div>

      {phase === "torn" ? null : (
        <button
          aria-label={`${label}: ${description}`}
          className={cn(
            "absolute inset-y-0 flex touch-none flex-col items-center justify-center gap-1 rounded-r-2xl outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 dark:ring-offset-zinc-950",
            colors.paper,
            colors.stub,
            "starting:-translate-x-3 starting:opacity-0 transition-[opacity,translate] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)]",
            phase === "tearing" ? "cursor-grabbing" : "cursor-grab"
          )}
          // A new stub per tear, so no inline style from the last one lingers.
          key={generation}
          onKeyDown={handleKeyDown}
          onLostPointerCapture={handlePointerUp}
          onPointerCancel={handlePointerUp}
          onPointerDown={handlePointerDown}
          onPointerMove={handlePointerMove}
          onPointerUp={handlePointerUp}
          ref={stubRef}
          style={{
            left: BODY_WIDTH,
            width: STUB_WIDTH,
            mask: stubMask,
            WebkitMask: stubMask,
            transformOrigin: "0 100%",
          }}
          type="button"
        >
          {/* The perforation. */}
          <span
            aria-hidden="true"
            className={cn(
              "absolute inset-y-2.5 left-0 border-l-2 border-dotted",
              colors.perforation
            )}
          />
          <svg
            aria-hidden="true"
            className="size-4"
            fill="none"
            stroke="currentColor"
            strokeLinecap="round"
            strokeLinejoin="round"
            strokeWidth={2}
            viewBox="0 0 24 24"
          >
            <path d="M6 6c6 0 12 3 12 11M14 14l4 4 4-4" />
          </svg>
          <span className="font-medium text-xs">{stubLabel}</span>
        </button>
      )}
      <span aria-live="polite" className="sr-only">
        {done ? confirmedLabel : ""}
      </span>
    </div>
  );
}
```


---

# V0 Button
> Open in v0 button that sends a component registry JSON to v0.dev for instant editing, built with React, the shadcn Button, and Tailwind CSS.

Source: https://kokonutui.com/docs/buttons/v0-button

## Installation

```bash
npx shadcn@latest add @kokonutui/v0-button
```

## Source

```tsx
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

const REGISTRY_URL = "https://kokonutui.com/r";

export default function V0Button({
  name = "liquid-glass-card",
  url = `${REGISTRY_URL}/${name}.json`,
  className,
  ...props
}: {
  name?: string;
  /** Registry item JSON to open in v0. Defaults to the KokonutUI entry for `name`. */
  url?: string;
} & React.ComponentProps<typeof Button>) {
  return (
    <Button
      aria-label="Open in v0"
      {...props}
      asChild
      className={cn(
        "gap-1 rounded-lg bg-black px-3 text-white text-xs shadow-none transition-[color,background-color,scale] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] hover:bg-zinc-800 motion-safe:active:scale-[0.97] dark:bg-white dark:text-black dark:hover:bg-zinc-200",
        className
      )}
    >
      <a
        href={`https://v0.dev/chat/api/open?url=${encodeURIComponent(url)}`}
        rel="noreferrer"
        target="_blank"
      >
        Open in{" "}
        <svg
          aria-hidden="true"
          fill="none"
          viewBox="0 0 40 20"
          xmlns="http://www.w3.org/2000/svg"
        >
          <path
            d="M23.3919 0H32.9188C36.7819 0 39.9136 3.13165 39.9136 6.99475V16.0805H36.0006V6.99475C36.0006 6.90167 35.9969 6.80925 35.9898 6.71766L26.4628 16.079C26.4949 16.08 26.5272 16.0805 26.5595 16.0805H36.0006V19.7762H26.5595C22.6964 19.7762 19.4788 16.6139 19.4788 12.7508V3.68923H23.3919V12.7508C23.3919 12.9253 23.4054 13.0977 23.4316 13.2668L33.1682 3.6995C33.0861 3.6927 33.003 3.68923 32.9188 3.68923H23.3919V0Z"
            fill="currentColor"
          />
          <path
            d="M13.7688 19.0956L0 3.68759H5.53933L13.6231 12.7337V3.68759H17.7535V17.5746C17.7535 19.6705 15.1654 20.6584 13.7688 19.0956Z"
            fill="currentColor"
          />
        </svg>
      </a>
    </Button>
  );
}
```


---

# Activity Terrain
> A contribution heatmap that tilts up into a 3D terrain you can turn, built with React and canvas.

Source: https://kokonutui.com/docs/cards/activity-terrain

## Installation

```bash
npx shadcn@latest add @kokonutui/activity-terrain
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Activity Terrain
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  useCallback,
  useEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

const DAYS = 7;
const GAP = 0.18;
// Tallest column, in cells.
const MAX_HEIGHT = 4.2;
const DEG = Math.PI / 180;
// Tilt of the terrain view; flat is looking straight down.
const PITCH_TERRAIN = 56 * DEG;
const YAW_TERRAIN = 18 * DEG;
// How far it turns before the edges start pulling back.
const YAW_LIMIT = 38 * DEG;
const PITCH_LIMIT = 66 * DEG;
// Drag, in radians per px.
const DRAG_YAW = 0.32 * DEG;
const DRAG_PITCH = 0.36 * DEG;
// Spin keeps going after a flick and slows on this half-life, in seconds.
const SPIN_HALF_LIFE = 0.16;
// The speed that coasts from straight on to the terrain's resting turn.
const SPIN_IN = (YAW_TERRAIN * Math.LN2) / SPIN_HALF_LIFE;
// Springs, per second squared and per second.
const PITCH_STIFFNESS = 140;
const PITCH_DAMPING = 2 * Math.sqrt(PITCH_STIFFNESS);
const EDGE_STIFFNESS = 180;
const BUMP_STIFFNESS = 400;
const BUMP_DAMPING = 2 * Math.sqrt(BUMP_STIFFNESS) * 0.7;
const BUMP = 0.45;
// Columns rise in a wave from where you grabbed; the far end lags by this
// share of the whole rise.
const WAVE = 0.7;
const PADDING = 28;
const REST_EPSILON = 0.0005;
const LABELS = ["Mon", "", "Wed", "", "Fri", "", ""];

export interface ActivityTerrainProps {
  /** Count per day, oldest first. */
  data?: number[];
  /** The day of the last value, as YYYY-MM-DD. */
  endDate?: string;
  title?: string;
  /** Start in the flat, heatmap view. */
  defaultFlat?: boolean;
  className?: string;
}

interface Cell {
  index: number;
  col: number;
  row: number;
  count: number;
  level: number;
  height: number;
  date: Date;
}

interface Pose {
  yaw: number;
  pitch: number;
  scale: number;
  cx: number;
  cy: number;
}

type Rgb = [number, number, number];

interface Palette {
  levels: Rgb[];
  accent: Rgb;
  text: string;
  font: string;
}

const clamp = (v: number, min: number, max: number) =>
  Math.min(max, Math.max(min, v));

// A gentle overshoot, so each column pops as it lands.
function easeOutBack(t: number) {
  const c = 1.4;
  const u = t - 1;
  return 1 + (c + 1) * u * u * u + c * u * u;
}

// Resistance past an edge: the further out, the less it moves.
function rubber(value: number, min: number, max: number) {
  if (value < min) {
    return min - 0.18 * (1 - Math.exp((value - min) / 0.18));
  }
  if (value > max) {
    return max + 0.18 * (1 - Math.exp((max - value) / 0.18));
  }
  return value;
}

// Deterministic demo data: busy weekdays, quiet weekends, a few streaks.
function demoData(weeks: number) {
  let seed = 7;
  const random = () => {
    seed = (seed * 16_807) % 2_147_483_647;
    return seed / 2_147_483_647;
  };
  const out: number[] = [];
  for (let i = 0; i < weeks * DAYS; i++) {
    const weekend = i % DAYS >= 5;
    const season = 0.55 + 0.45 * Math.sin(i / 23);
    const streak = random() > 0.82 ? 2.2 : 1;
    const quiet = random() < (weekend ? 0.55 : 0.12);
    out.push(
      quiet ? 0 : Math.round((weekend ? 3 : 9) * season * streak * random())
    );
  }
  return out;
}

const DEFAULT_DATA = demoData(26);

function parseDay(value: string) {
  const [y, m, d] = value.split("-").map(Number);
  return new Date(Date.UTC(y, m - 1, d));
}

function buildCells(data: number[], endDate: string) {
  const end = parseDay(endDate);
  const start = new Date(end.getTime() - (data.length - 1) * 86_400_000);
  // Rows run Monday to Sunday.
  const offset = (start.getUTCDay() + 6) % 7;
  const max = Math.max(1, ...data);
  return data.map((count, index): Cell => {
    const slot = index + offset;
    const norm = count / max;
    return {
      index,
      col: Math.floor(slot / DAYS),
      row: slot % DAYS,
      count,
      level: count === 0 ? 0 : Math.ceil(norm * 4),
      height: 0.06 + norm ** 0.85 * MAX_HEIGHT,
      date: new Date(start.getTime() + index * 86_400_000),
    };
  });
}

function hexToRgb(value: string): Rgb {
  const hex = value.trim().replace("#", "");
  const n = Number.parseInt(
    hex.length === 3 ? hex.replace(/./g, "$&$&") : hex,
    16
  );
  return [Math.floor(n / 65_536) % 256, Math.floor(n / 256) % 256, n % 256];
}

function shade([r, g, b]: Rgb, amount: number) {
  const k = 1 - amount;
  return `rgb(${Math.round(r * k)},${Math.round(g * k)},${Math.round(b * k)})`;
}

function readPalette(node: HTMLElement): Palette {
  const style = getComputedStyle(node);
  const read = (name: string) => style.getPropertyValue(name) || "#888888";
  return {
    levels: [0, 1, 2, 3, 4].map((l) => hexToRgb(read(`--terrain-${l}`))),
    accent: hexToRgb(read("--terrain-accent")),
    text: read("--terrain-text"),
    font: style.fontFamily,
  };
}

function project(pose: Pose, x: number, y: number, z: number) {
  const cos = Math.cos(pose.yaw);
  const sin = Math.sin(pose.yaw);
  const xr = x * cos - z * sin;
  const zr = x * sin + z * cos;
  return [
    pose.cx + xr * pose.scale,
    pose.cy +
      (zr * Math.cos(pose.pitch) - y * Math.sin(pose.pitch)) * pose.scale,
  ];
}

/** The faces of one column that face the camera, top last. */
function visibleFaces(
  pose: Pose,
  x0: number,
  z0: number,
  h: number
): { points: number[][]; tone: number }[] {
  const x1 = x0 + 1 - GAP;
  const z1 = z0 + 1 - GAP;
  const p = (x: number, y: number, z: number) => project(pose, x, y, z);
  const faces: { points: number[][]; tone: number }[] = [];
  const sin = Math.sin(pose.yaw);
  const cos = Math.cos(pose.yaw);
  if (h > 0.02 && pose.pitch > 0.01) {
    // Of the four walls, the ones whose outward side points at the camera.
    if (cos > 0) {
      faces.push({
        points: [p(x0, 0, z1), p(x1, 0, z1), p(x1, h, z1), p(x0, h, z1)],
        tone: 0.22,
      });
    } else {
      faces.push({
        points: [p(x0, 0, z0), p(x1, 0, z0), p(x1, h, z0), p(x0, h, z0)],
        tone: 0.22,
      });
    }
    if (sin > 0.001) {
      faces.push({
        points: [p(x1, 0, z0), p(x1, 0, z1), p(x1, h, z1), p(x1, h, z0)],
        tone: 0.38,
      });
    } else if (sin < -0.001) {
      faces.push({
        points: [p(x0, 0, z0), p(x0, 0, z1), p(x0, h, z1), p(x0, h, z0)],
        tone: 0.38,
      });
    }
  }
  faces.push({
    points: [p(x0, h, z0), p(x1, h, z0), p(x1, h, z1), p(x0, h, z1)],
    tone: 0,
  });
  return faces;
}

function inside(points: number[][], x: number, y: number) {
  let hit = false;
  for (let i = 0, j = points.length - 1; i < points.length; j = i++) {
    const [xi, yi] = points[i];
    const [xj, yj] = points[j];
    if (yi > y !== yj > y && x < ((xj - xi) * (y - yi)) / (yj - yi) + xi) {
      hit = !hit;
    }
  }
  return hit;
}

function polygon(ctx: CanvasRenderingContext2D, points: number[][]) {
  ctx.beginPath();
  ctx.moveTo(points[0][0], points[0][1]);
  for (let i = 1; i < points.length; i++) {
    ctx.lineTo(points[i][0], points[i][1]);
  }
  ctx.closePath();
}

const formatDay = (date: Date) =>
  date.toLocaleDateString("en-US", {
    weekday: "short",
    month: "short",
    day: "numeric",
    timeZone: "UTC",
  });
const formatMonth = (date: Date) =>
  date.toLocaleDateString("en-US", { month: "short", timeZone: "UTC" });

export default function ActivityTerrain({
  data = DEFAULT_DATA,
  endDate = "2026-10-11",
  title = "Activity",
  defaultFlat = false,
  className,
}: ActivityTerrainProps) {
  const cells = useMemo(() => buildCells(data, endDate), [data, endDate]);
  const weeks = (cells.at(-1)?.col ?? 0) + 1;
  const total = useMemo(() => data.reduce((sum, n) => sum + n, 0), [data]);
  const [flat, setFlat] = useState(defaultFlat);
  const [active, setActive] = useState<Cell | null>(null);
  const [dragging, setDragging] = useState(false);

  const canvasRef = useRef<HTMLCanvasElement>(null);
  const paletteRef = useRef<Palette | null>(null);
  const sim = useRef({
    yaw: 0,
    yawSpeed: 0,
    // The intro tilts it up from flat once it's on screen.
    pitch: 0,
    pitchSpeed: 0,
    pitchTarget: defaultFlat ? 0 : PITCH_TERRAIN,
    bumps: new Float64Array(cells.length),
    bumpSpeeds: new Float64Array(cells.length),
    hovered: -1,
    origin: { col: 0, row: 3 },
    width: 0,
    height: 0,
    dpr: 1,
    drag: null as null | {
      id: number;
      x: number;
      y: number;
      yaw: number;
      pitch: number;
      moved: boolean;
      samples: { t: number; x: number; y: number }[];
    },
    raf: 0,
    last: 0,
    visible: false,
    started: false,
    reduceMotion: false,
  });
  const cellsRef = useRef(cells);
  cellsRef.current = cells;
  if (sim.current.bumps.length !== cells.length) {
    sim.current.bumps = new Float64Array(cells.length);
    sim.current.bumpSpeeds = new Float64Array(cells.length);
  }

  // How tall each column stands right now: the rise travels as a wave out
  // from the origin, and each column overshoots a touch as it lands.
  const columnHeight = useCallback(
    (cell: Cell, lift: number) => {
      const s = sim.current;
      const span = Math.hypot(weeks, DAYS) || 1;
      const d =
        Math.hypot(cell.col - s.origin.col, cell.row - s.origin.row) / span;
      const local = clamp(lift * (1 + WAVE) - d * WAVE, 0, 1);
      return cell.height * easeOutBack(local) + s.bumps[cell.index];
    },
    [weeks]
  );

  const pose = useCallback((): Pose & { lift: number } => {
    const s = sim.current;
    const lift = clamp(s.pitch / PITCH_TERRAIN, 0, 1.2);
    // Fit the whole board, at its current turn and tilt, into the canvas.
    const w = weeks;
    const corners = [
      [0, 0],
      [w, 0],
      [0, DAYS],
      [w, DAYS],
    ];
    const probe: Pose = { yaw: s.yaw, pitch: s.pitch, scale: 1, cx: 0, cy: 0 };
    let minX = Number.POSITIVE_INFINITY;
    let maxX = Number.NEGATIVE_INFINITY;
    let minY = Number.POSITIVE_INFINITY;
    let maxY = Number.NEGATIVE_INFINITY;
    for (const [x, z] of corners) {
      for (const y of [0, MAX_HEIGHT * Math.min(lift, 1)]) {
        const [px, py] = project(probe, x - w / 2, y, z - DAYS / 2);
        minX = Math.min(minX, px);
        maxX = Math.max(maxX, px);
        minY = Math.min(minY, py);
        maxY = Math.max(maxY, py);
      }
    }
    const scale = Math.min(
      (s.width - PADDING * 2) / (maxX - minX),
      (s.height - PADDING * 2) / (maxY - minY)
    );
    return {
      yaw: s.yaw,
      pitch: s.pitch,
      scale,
      cx: s.width / 2 - ((minX + maxX) / 2) * scale,
      cy: s.height / 2 - ((minY + maxY) / 2) * scale + 6,
      lift,
    };
  }, [weeks]);

  // Back to front: the further a column's base, the earlier it's drawn.
  const ordered = useCallback(
    (p: Pose) => {
      const sin = Math.sin(p.yaw);
      const cos = Math.cos(p.yaw);
      const depth = (c: Cell) =>
        (c.col + 0.5 - weeks / 2) * sin + (c.row + 0.5 - DAYS / 2) * cos;
      return [...cellsRef.current].sort((a, b) => depth(a) - depth(b));
    },
    [weeks]
  );

  const drawLabels = useCallback(
    (
      ctx: CanvasRenderingContext2D,
      p: Pose,
      lift: number,
      palette: Palette
    ) => {
      // Labels lie on the ground, so they'd hide behind the columns; they
      // fade out as the terrain rises, and the readout names each day.
      const alpha = clamp(1 - lift * 1.6, 0, 1);
      if (alpha === 0) {
        return;
      }
      const list = cellsRef.current;
      ctx.globalAlpha = alpha;
      ctx.fillStyle = palette.text;
      ctx.font = `11px ${palette.font}`;
      ctx.textBaseline = "middle";
      ctx.textAlign = "left";
      let month = -1;
      for (const cell of list) {
        if (cell.row !== 0 && cell.index !== 0) {
          continue;
        }
        const m = cell.date.getUTCMonth();
        if (m !== month && cell.col < weeks - 1) {
          month = m;
          const [x, y] = project(p, cell.col - weeks / 2, 0, -0.75 - DAYS / 2);
          ctx.fillText(formatMonth(cell.date), x, y);
        }
      }
      ctx.textAlign = "right";
      for (let row = 0; row < DAYS; row++) {
        if (LABELS[row]) {
          const [x, y] = project(p, -0.35 - weeks / 2, 0, row + 0.4 - DAYS / 2);
          ctx.fillText(LABELS[row], x, y);
        }
      }
      ctx.globalAlpha = 1;
    },
    [weeks]
  );

  const draw = useCallback(() => {
    const s = sim.current;
    const canvas = canvasRef.current;
    const ctx = canvas?.getContext("2d");
    if (!(canvas && ctx && s.width)) {
      return;
    }
    // Colours come from CSS, read once per theme rather than every frame.
    paletteRef.current ??= readPalette(canvas);
    const palette = paletteRef.current;
    const p = pose();
    ctx.setTransform(s.dpr, 0, 0, s.dpr, 0, 0);
    ctx.clearRect(0, 0, s.width, s.height);
    drawLabels(ctx, p, p.lift, palette);
    ctx.lineJoin = "round";
    for (const cell of ordered(p)) {
      const h = columnHeight(cell, p.lift);
      const color =
        cell.index === s.hovered ? palette.accent : palette.levels[cell.level];
      for (const face of visibleFaces(
        p,
        cell.col - weeks / 2,
        cell.row - DAYS / 2,
        h
      )) {
        polygon(ctx, face.points);
        const fill = shade(color, face.tone);
        ctx.fillStyle = fill;
        ctx.fill();
        // A hairline in the same colour closes the seams between faces.
        ctx.strokeStyle = fill;
        ctx.lineWidth = 0.6;
        ctx.stroke();
      }
    }
  }, [columnHeight, drawLabels, ordered, pose, weeks]);

  const hitTest = useCallback(
    (x: number, y: number) => {
      const p = pose();
      const list = ordered(p);
      for (let i = list.length - 1; i >= 0; i--) {
        const cell = list[i];
        const h = columnHeight(cell, p.lift);
        for (const face of visibleFaces(
          p,
          cell.col - weeks / 2,
          cell.row - DAYS / 2,
          h
        )) {
          if (inside(face.points, x, y)) {
            return cell;
          }
        }
      }
      return null;
    },
    [columnHeight, ordered, pose, weeks]
  );

  const stepSprings = useCallback((dt: number) => {
    const s = sim.current;
    let energy = 0;
    if (!s.drag) {
      // Spin coasts, then the edge pulls it back in range.
      s.yawSpeed *= 0.5 ** (dt / SPIN_HALF_LIFE);
      let target = s.yaw;
      if (s.pitchTarget === 0) {
        // Flat is always square on.
        target = 0;
      } else if (s.yaw > YAW_LIMIT) {
        target = YAW_LIMIT;
      } else if (s.yaw < -YAW_LIMIT) {
        target = -YAW_LIMIT;
      }
      if (target !== s.yaw) {
        s.yawSpeed +=
          ((target - s.yaw) * EDGE_STIFFNESS -
            s.yawSpeed * 2 * Math.sqrt(EDGE_STIFFNESS)) *
          dt;
      }
      s.yaw += s.yawSpeed * dt;
      energy = Math.max(energy, Math.abs(s.yawSpeed), Math.abs(target - s.yaw));

      const force =
        (s.pitchTarget - s.pitch) * PITCH_STIFFNESS -
        s.pitchSpeed * PITCH_DAMPING;
      s.pitchSpeed += force * dt;
      s.pitch += s.pitchSpeed * dt;
      energy = Math.max(
        energy,
        Math.abs(s.pitchSpeed),
        Math.abs(s.pitchTarget - s.pitch)
      );
    }
    for (let i = 0; i < s.bumps.length; i++) {
      const target = i === s.hovered && s.pitch > 0.1 ? BUMP : 0;
      s.bumpSpeeds[i] +=
        ((target - s.bumps[i]) * BUMP_STIFFNESS -
          s.bumpSpeeds[i] * BUMP_DAMPING) *
        dt;
      s.bumps[i] += s.bumpSpeeds[i] * dt;
      energy = Math.max(
        energy,
        Math.abs(s.bumpSpeeds[i]) * 0.1,
        Math.abs(target - s.bumps[i])
      );
    }
    return energy;
  }, []);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const dt = s.last ? Math.min((now - s.last) / 1000, 1 / 30) : 1 / 60;
      s.last = now;
      const energy = stepSprings(dt);
      draw();
      if ((s.drag || energy > REST_EPSILON) && s.visible) {
        s.raf = requestAnimationFrame(tick);
      } else {
        s.last = 0;
      }
    },
    [draw, stepSprings]
  );

  // Swing round from straight on as it tilts up, coasting to a stop at
  // the resting turn.
  const turnIn = useCallback(() => {
    const s = sim.current;
    if (Math.abs(s.yaw) > 2 * DEG) {
      return;
    }
    if (s.reduceMotion) {
      s.yaw = YAW_TERRAIN;
    } else {
      s.yawSpeed = SPIN_IN;
    }
  }, []);

  const wake = useCallback(() => {
    const s = sim.current;
    if (s.reduceMotion) {
      // No travel: everything lands where it's going.
      s.pitch = s.pitchTarget;
      s.yaw = clamp(s.yaw, -YAW_LIMIT, YAW_LIMIT);
      s.pitchSpeed = 0;
      s.yawSpeed = 0;
      s.bumps.fill(0);
      draw();
      return;
    }
    if (!s.raf && s.visible) {
      s.raf = requestAnimationFrame(tick);
    }
  }, [draw, tick]);

  useEffect(() => {
    const s = sim.current;
    const canvas = canvasRef.current;
    if (!canvas) {
      return;
    }
    const motion = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = motion.matches;
    const resize = new ResizeObserver(([entry]) => {
      s.width = entry.contentRect.width;
      s.height = entry.contentRect.height;
      s.dpr = Math.min(window.devicePixelRatio || 1, 2);
      canvas.width = Math.round(s.width * s.dpr);
      canvas.height = Math.round(s.height * s.dpr);
      draw();
    });
    resize.observe(canvas);

    let onScreen = false;
    const update = () => {
      s.visible = onScreen && !document.hidden;
      if (s.visible) {
        if (!s.started) {
          s.started = true;
          if (s.pitchTarget > 0) {
            turnIn();
          }
        }
        wake();
      } else if (s.raf) {
        cancelAnimationFrame(s.raf);
        s.raf = 0;
        s.last = 0;
      }
    };
    const intersection = new IntersectionObserver(([entry]) => {
      onScreen = entry.isIntersecting;
      update();
    });
    intersection.observe(canvas);
    document.addEventListener("visibilitychange", update);

    // Repaint when the theme flips, since the canvas reads its colours.
    const repaint = () => {
      paletteRef.current = null;
      draw();
    };
    const theme = new MutationObserver(repaint);
    theme.observe(document.documentElement, {
      attributes: true,
      attributeFilter: ["class", "style", "data-theme"],
    });
    const scheme = window.matchMedia("(prefers-color-scheme: dark)");
    scheme.addEventListener("change", repaint);

    return () => {
      resize.disconnect();
      intersection.disconnect();
      theme.disconnect();
      scheme.removeEventListener("change", repaint);
      document.removeEventListener("visibilitychange", update);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, [draw, turnIn, wake]);

  const setView = (
    nextFlat: boolean,
    origin?: { col: number; row: number }
  ) => {
    const s = sim.current;
    setFlat(nextFlat);
    s.origin = origin ?? { col: nextFlat ? weeks : 0, row: 3 };
    s.pitchTarget = nextFlat ? 0 : PITCH_TERRAIN;
    s.yawSpeed = 0;
    if (!nextFlat) {
      turnIn();
    }
    wake();
  };

  const localPoint = (event: PointerEvent) => {
    const rect = canvasRef.current?.getBoundingClientRect();
    return rect
      ? { x: event.clientX - rect.left, y: event.clientY - rect.top }
      : { x: 0, y: 0 };
  };

  const hover = (cell: Cell | null) => {
    const s = sim.current;
    const index = cell ? cell.index : -1;
    if (index !== s.hovered) {
      s.hovered = index;
      setActive(cell);
      if (s.reduceMotion) {
        draw();
      } else {
        wake();
      }
    }
  };

  const handlePointerDown = (event: PointerEvent<HTMLCanvasElement>) => {
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    const s = sim.current;
    const { x, y } = localPoint(event);
    event.currentTarget.setPointerCapture(event.pointerId);
    const cell = hitTest(x, y);
    if (cell) {
      s.origin = { col: cell.col, row: cell.row };
    }
    s.drag = {
      id: event.pointerId,
      x: event.clientX,
      y: event.clientY,
      yaw: s.yaw,
      pitch: s.pitch,
      moved: false,
      samples: [{ t: event.timeStamp, x: event.clientX, y: event.clientY }],
    };
    s.yawSpeed = 0;
    s.pitchSpeed = 0;
    setDragging(true);
    hover(cell);
    wake();
  };

  const handlePointerMove = (event: PointerEvent<HTMLCanvasElement>) => {
    const s = sim.current;
    const drag = s.drag;
    if (!drag || drag.id !== event.pointerId) {
      if (event.pointerType === "mouse") {
        const { x, y } = localPoint(event);
        hover(hitTest(x, y));
      }
      return;
    }
    const dx = event.clientX - drag.x;
    const dy = event.clientY - drag.y;
    if (!drag.moved && Math.hypot(dx, dy) > 4) {
      drag.moved = true;
    }
    if (!drag.moved) {
      return;
    }
    s.yaw = rubber(drag.yaw + dx * DRAG_YAW, -YAW_LIMIT, YAW_LIMIT);
    s.pitch = rubber(drag.pitch + dy * DRAG_PITCH, 0, PITCH_LIMIT);
    drag.samples.push({
      t: event.timeStamp,
      x: event.clientX,
      y: event.clientY,
    });
    if (drag.samples.length > 5) {
      drag.samples.shift();
    }
    if (s.reduceMotion) {
      draw();
    } else {
      wake();
    }
  };

  const handlePointerUp = (event: PointerEvent<HTMLCanvasElement>) => {
    const s = sim.current;
    const drag = s.drag;
    if (!drag || drag.id !== event.pointerId) {
      return;
    }
    s.drag = null;
    setDragging(false);
    if (!drag.moved) {
      wake();
      return;
    }
    // Velocity from the last few samples, in px per second.
    const first = drag.samples[0];
    const lastSample = drag.samples.at(-1) ?? first;
    const dt = Math.max((lastSample.t - first.t) / 1000, 0.016);
    const vx = (lastSample.x - first.x) / dt;
    const vy = (lastSample.y - first.y) / dt;
    const recent = event.timeStamp - lastSample.t < 80;
    s.yawSpeed = recent ? vx * DRAG_YAW : 0;
    s.pitchSpeed = recent ? vy * DRAG_PITCH : 0;
    // Land on whichever view the throw is heading for.
    const projected = s.pitch + s.pitchSpeed * 0.15;
    const nextFlat = projected < PITCH_TERRAIN / 2;
    setFlat(nextFlat);
    s.pitchTarget = nextFlat ? 0 : PITCH_TERRAIN;
    wake();
  };

  const handlePointerLeave = (event: PointerEvent<HTMLCanvasElement>) => {
    if (!sim.current.drag && event.pointerType === "mouse") {
      hover(null);
    }
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLCanvasElement>) => {
    const moves: Record<string, [number, number]> = {
      ArrowLeft: [-1, 0],
      ArrowRight: [1, 0],
      ArrowUp: [0, -1],
      ArrowDown: [0, 1],
    };
    const move = moves[event.key];
    if (!move) {
      return;
    }
    event.preventDefault();
    const list = cellsRef.current;
    const current = list[sim.current.hovered] ?? list.at(-1);
    if (!current) {
      return;
    }
    const col = current.col + move[0];
    const row = current.row + move[1];
    const next = list.find((c) => c.col === col && c.row === row);
    hover(next ?? current);
  };

  const readout = active
    ? `${active.count} ${active.count === 1 ? "contribution" : "contributions"} on ${formatDay(active.date)}`
    : `${total.toLocaleString("en-US")} contributions in the last ${weeks} weeks`;

  return (
    <div
      className={cn(
        "w-full max-w-2xl select-none rounded-3xl border border-zinc-200 bg-white text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        "[--terrain-0:#f4f4f5] [--terrain-1:#d4d4d8] [--terrain-2:#a1a1aa] [--terrain-3:#52525b] [--terrain-4:#18181b] [--terrain-accent:#10b981] [--terrain-text:#a1a1aa]",
        "dark:[--terrain-0:#27272a] dark:[--terrain-1:#3f3f46] dark:[--terrain-2:#71717a] dark:[--terrain-3:#a1a1aa] dark:[--terrain-4:#f4f4f5] dark:[--terrain-accent:#34d399] dark:[--terrain-text:#71717a]",
        className
      )}
    >
      <div className="flex items-start justify-between gap-4 p-5 pb-0">
        <div className="min-w-0">
          <p className="font-medium text-sm">{title}</p>
          <p
            aria-live="polite"
            className="mt-0.5 truncate text-sm text-zinc-500 tabular-nums dark:text-zinc-400"
          >
            {readout}
          </p>
        </div>
        <div className="flex shrink-0 rounded-full bg-zinc-100 p-0.5 text-xs dark:bg-zinc-900">
          {(
            [
              ["Flat", true],
              ["Terrain", false],
            ] as const
          ).map(([name, value]) => (
            <button
              aria-pressed={flat === value}
              className={cn(
                "rounded-full px-3 py-1 font-medium outline-none transition-colors duration-200 ease-out focus-visible:ring-2 focus-visible:ring-zinc-400",
                flat === value
                  ? "bg-white text-zinc-900 shadow-sm dark:bg-zinc-700 dark:text-zinc-50"
                  : "text-zinc-500 hover:text-zinc-900 dark:text-zinc-400 dark:hover:text-zinc-100"
              )}
              key={name}
              onClick={() => flat !== value && setView(value)}
              type="button"
            >
              {name}
            </button>
          ))}
        </div>
      </div>

      <canvas
        aria-label={`${title}: ${total} contributions over ${weeks} weeks. Use the arrow keys to read each day.`}
        className={cn(
          "block h-72 w-full touch-pan-y rounded-b-3xl outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-inset",
          dragging ? "cursor-grabbing" : "cursor-grab"
        )}
        onKeyDown={handleKeyDown}
        onLostPointerCapture={handlePointerUp}
        onPointerCancel={handlePointerUp}
        onPointerDown={handlePointerDown}
        onPointerLeave={handlePointerLeave}
        onPointerMove={handlePointerMove}
        onPointerUp={handlePointerUp}
        ref={canvasRef}
        role="img"
        tabIndex={0}
      />

      <div className="flex items-center justify-end gap-1 px-5 pb-4 text-xs text-zinc-500 dark:text-zinc-400">
        <span className="mr-1">Less</span>
        {[0, 1, 2, 3, 4].map((level) => (
          <span
            className="size-2.5 rounded-[3px]"
            key={level}
            style={{ background: `var(--terrain-${level})` }}
          />
        ))}
        <span className="ml-1">More</span>
      </div>
    </div>
  );
}
```


---

# Apple Activity Card
> Activity rings that draw with a count-up, lap past 100% with a shadowed end cap and dim to focus, built with React and Motion.

Source: https://kokonutui.com/docs/cards/apple-activity-card

## Installation

```bash
npx shadcn@latest add @kokonutui/apple-activity-card
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: Apple Activity Card
 * @version: 1.1.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  animate,
  MotionConfig,
  motion,
  useInView,
  useReducedMotion,
} from "motion/react";
import { type CSSProperties, useEffect, useId, useRef, useState } from "react";
import { cn } from "@/lib/utils";

export interface ActivityData {
  label: string;
  color: string;
  colorEnd: string;
  size: number;
  /** Can go past `target`: the ring keeps going for another lap. */
  current: number;
  target: number;
  unit: string;
}

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const STROKE = 16;
// Rings draw one after another, this far apart (s).
const STAGGER = 0.18;
// Time for the first lap; anything past the goal adds up to OVER_S more.
const DRAW_S = 1.2;
const OVER_S = 0.6;
// More than three laps would just be a solid ring.
const MAX_LAPS = 3;

const SAMPLE_ACTIVITIES: ActivityData[] = [
  {
    label: "MOVE",
    color: "#FF2D55",
    colorEnd: "#FF6B8B",
    size: 200,
    current: 479,
    target: 800,
    unit: "CAL",
  },
  {
    label: "EXERCISE",
    color: "#A3F900",
    colorEnd: "#C5FF4D",
    size: 160,
    current: 42,
    target: 30,
    unit: "MIN",
  },
  {
    label: "STAND",
    color: "#04C7DD",
    colorEnd: "#4DDFED",
    size: 120,
    current: 6,
    target: 12,
    unit: "HR",
  },
];

/** Progress in laps (1 = goal), capped so a huge value stays legible. */
const ratioOf = (data: ActivityData) =>
  data.target > 0
    ? Math.min(Math.max(data.current / data.target, 0), MAX_LAPS)
    : 0;

/** Duration of one ring's draw; its count-up runs on the same clock. */
const drawSeconds = (ratio: number) =>
  DRAW_S + OVER_S * Math.min(Math.max(ratio - 1, 0), 1);

interface RingNodes {
  base: SVGCircleElement | null;
  lap: SVGCircleElement | null;
  cap: SVGGElement | null;
  pulse: SVGCircleElement | null;
  count: HTMLSpanElement | null;
}

/**
 * Write one frame of a ring's draw straight to the DOM: `p` is progress in
 * laps. Past the goal the first lap stays full and a second circle draws
 * the overflow on top of it, led by a shadowed end cap, as on the Watch.
 */
function paintRing(
  nodes: RingNodes,
  data: Pick<ActivityData, "size" | "current">,
  p: number,
  ratio: number
) {
  const radius = (data.size - STROKE) / 2;
  const circumference = radius * 2 * Math.PI;
  nodes.base?.setAttribute(
    "stroke-dashoffset",
    `${(1 - Math.min(p, 1)) * circumference}`
  );
  const over = p > 1;
  // How far into the latest lap; a whole number of laps is a full lap.
  const rest = over ? p - Math.floor(p) || 1 : 0;
  if (nodes.lap) {
    nodes.lap.setAttribute(
      "stroke-dashoffset",
      `${(1 - rest) * circumference}`
    );
    nodes.lap.style.opacity = over ? "1" : "0";
  }
  if (nodes.cap) {
    nodes.cap.style.transform = `rotate(${rest * 360}deg)`;
    nodes.cap.style.opacity = over ? "1" : "0";
  }
  if (nodes.count) {
    // Count in step with the ring, landing exactly on the real value.
    nodes.count.textContent =
      p >= ratio
        ? `${data.current}`
        : `${Math.round((p / ratio) * data.current)}`;
  }
}

function CircleProgress({
  data,
  index,
  inView,
  reduceMotion,
  dimmed,
  onActive,
  countRef,
}: {
  data: ActivityData;
  index: number;
  inView: boolean;
  reduceMotion: boolean;
  dimmed: boolean;
  onActive: (active: boolean) => void;
  countRef: { current: HTMLSpanElement | null };
}) {
  const radius = (data.size - STROKE) / 2;
  const circumference = radius * 2 * Math.PI;
  const center = data.size / 2;
  const ratio = ratioOf(data);
  const progressLabel = `${data.label}: ${data.current} of ${data.target} ${data.unit}, ${Math.round(ratio * 100)}%`;

  const gradientId = useId();
  const shadowId = useId();
  const nodes = useRef<RingNodes>({
    base: null,
    lap: null,
    cap: null,
    pulse: null,
    count: null,
  });

  // Where the ring last stood, so new values carry on from there instead of
  // redrawing from empty. Null until the first draw.
  const shown = useRef<number | null>(null);
  // Keyed on the values, not the object: a parent re-rendering with the same
  // numbers in a fresh array must not restart the draw.
  const { size, current } = data;

  useEffect(() => {
    if (!inView) {
      return;
    }
    const ringNodes = { ...nodes.current, count: countRef.current };
    const ring = { size, current };
    if (reduceMotion || ratio === 0) {
      paintRing(ringNodes, ring, ratio, ratio);
      shown.current = ratio;
      return;
    }
    const from = shown.current;
    // First draw: start from zero right away, so the number doesn't show its
    // final value while the ring waits for its turn.
    if (from === null) {
      paintRing(ringNodes, ring, 0, ratio);
    }
    let pulsed = (from ?? 0) >= 1;
    const controls = animate(from ?? 0, ratio, {
      duration: drawSeconds(ratio),
      delay: from === null ? index * STAGGER : 0,
      ease: EASE_OUT,
      onUpdate: (p) => {
        shown.current = p;
        paintRing(ringNodes, ring, p, ratio);
        // The goal is hit: the cap pulses once at the top of the ring.
        if (!pulsed && p >= 1) {
          pulsed = true;
          ringNodes.pulse?.animate(
            [
              { transform: "scale(1)", opacity: 0.6 },
              { transform: "scale(2.4)", opacity: 0 },
            ],
            { duration: 560, easing: "cubic-bezier(0.23, 1, 0.32, 1)" }
          );
        }
      },
    });
    return () => controls.stop();
  }, [inView, reduceMotion, size, current, ratio, index, countRef]);

  return (
    <motion.div
      animate={inView ? { opacity: 1, transform: "scale(1)" } : undefined}
      className="pointer-events-none absolute inset-0 flex items-center justify-center"
      initial={{ opacity: 0, transform: "scale(0.96)" }}
      transition={{ duration: 0.3, delay: index * STAGGER, ease: EASE_OUT }}
    >
      {/* biome-ignore lint/a11y: the ring is focusable so keyboard users get the same focus dimming as hover; it has no action of its own. */}
      <svg
        aria-label={progressLabel}
        className={cn(
          "-rotate-90 overflow-visible rounded-full outline-none transition-opacity duration-200 ease-out focus-visible:ring-2 focus-visible:ring-zinc-400",
          dimmed && "opacity-25"
        )}
        height={data.size}
        onBlur={() => onActive(false)}
        onFocus={() => onActive(true)}
        role="img"
        // biome-ignore lint/a11y/noNoninteractiveTabindex: see above; focus only dims the other rings.
        tabIndex={0}
        viewBox={`0 0 ${data.size} ${data.size}`}
        width={data.size}
      >
        <title>{progressLabel}</title>
        <defs>
          <linearGradient id={gradientId} x1="0%" x2="100%" y1="0%" y2="100%">
            <stop offset="0%" stopColor={data.color} />
            <stop offset="100%" stopColor={data.colorEnd} />
          </linearGradient>
          {/* Lets the second lap read as lying on top of the first. */}
          <filter height="300%" id={shadowId} width="300%" x="-100%" y="-100%">
            <feDropShadow
              dx="0"
              dy="-2.5"
              floodColor="#000"
              floodOpacity="0.5"
              stdDeviation="2"
            />
          </filter>
        </defs>

        {/* The track is the ring's hover target, so each ring only reacts
            over its own band. */}
        <circle
          className="text-zinc-200/60 dark:text-zinc-800/60"
          cx={center}
          cy={center}
          fill="none"
          onPointerEnter={(event) => {
            if (event.pointerType === "mouse") {
              onActive(true);
            }
          }}
          onPointerLeave={() => onActive(false)}
          pointerEvents="stroke"
          r={radius}
          stroke="currentColor"
          strokeWidth={STROKE}
        />
        <circle
          cx={center}
          cy={center}
          fill="none"
          pointerEvents="none"
          r={radius}
          ref={(node) => {
            nodes.current.base = node;
          }}
          stroke={`url(#${gradientId})`}
          strokeDasharray={circumference}
          strokeDashoffset={circumference}
          strokeLinecap="round"
          strokeWidth={STROKE}
        />
        <circle
          cx={center}
          cy={center}
          fill="none"
          pointerEvents="none"
          r={radius}
          ref={(node) => {
            nodes.current.lap = node;
          }}
          stroke={data.colorEnd}
          strokeDasharray={circumference}
          strokeDashoffset={circumference}
          strokeLinecap="round"
          strokeWidth={STROKE}
          style={{ opacity: 0 }}
        />
        {/* End cap of the overflow lap; its shadow shows it passing over
            the start of the ring. */}
        <g
          pointerEvents="none"
          ref={(node) => {
            nodes.current.cap = node;
          }}
          style={{
            opacity: 0,
            transformBox: "view-box",
            transformOrigin: "center",
          }}
        >
          <circle
            cx={center + radius}
            cy={center}
            fill={data.colorEnd}
            filter={`url(#${shadowId})`}
            r={STROKE / 2}
          />
        </g>
        {/* Goal pulse, at the top of the ring where the first lap closes. */}
        <circle
          cx={center + radius}
          cy={center}
          fill="none"
          pointerEvents="none"
          r={STROKE / 2}
          ref={(node) => {
            nodes.current.pulse = node;
          }}
          stroke={data.colorEnd}
          strokeWidth={2}
          style={{
            opacity: 0,
            transformBox: "fill-box",
            transformOrigin: "center",
          }}
        />
      </svg>
    </motion.div>
  );
}

function DetailedActivityInfo({
  activities,
  inView,
  active,
  onActive,
  countRefs,
}: {
  activities: ActivityData[];
  inView: boolean;
  active: number | null;
  onActive: (index: number | null) => void;
  countRefs: { current: HTMLSpanElement | null }[];
}) {
  return (
    <motion.ul
      animate={
        inView ? { opacity: 1, transform: "translateX(0px)" } : undefined
      }
      className="flex flex-col gap-6"
      initial={{ opacity: 0, transform: "translateX(16px)" }}
      transition={{ duration: 0.5, delay: 0.3, ease: EASE_OUT }}
    >
      {activities.map((activity, index) => (
        <li
          className={cn(
            "flex flex-col transition-opacity duration-200 ease-out",
            active !== null && active !== index && "opacity-40"
          )}
          key={activity.label}
          onPointerEnter={(event) => {
            if (event.pointerType === "mouse") {
              onActive(index);
            }
          }}
          onPointerLeave={() => onActive(null)}
        >
          <span className="font-medium text-sm text-zinc-600 dark:text-zinc-400">
            {activity.label}
          </span>
          {/* The ring hues are too light for text on white, so light mode
              darkens them (3:1 or better for this large text). */}
          <span
            className="font-semibold text-2xl text-[color-mix(in_oklab,var(--activity-color)_70%,black)] tabular-nums dark:text-(--activity-color)"
            style={{ "--activity-color": activity.color } as CSSProperties}
          >
            <span className="sr-only">
              {activity.current} of {activity.target} {activity.unit}
            </span>
            <span aria-hidden="true">
              <span
                ref={(node) => {
                  const slot = countRefs[index];
                  if (slot) {
                    slot.current = node;
                  }
                }}
              >
                {activity.current}
              </span>
              /{activity.target}
              <span className="ml-1 text-base text-zinc-600 dark:text-zinc-400">
                {activity.unit}
              </span>
            </span>
          </span>
        </li>
      ))}
    </motion.ul>
  );
}

export default function AppleActivityCard({
  title = "Activity Rings",
  titleAs = "h2",
  activities = SAMPLE_ACTIVITIES,
  className,
}: {
  title?: string;
  /** Heading level for the title, to fit the page outline. */
  titleAs?: "h1" | "h2" | "h3" | "h4" | "h5" | "h6";
  /** Rings, outermost first. Defaults to sample data. */
  activities?: ActivityData[];
  className?: string;
}) {
  const ref = useRef<HTMLDivElement>(null);
  const Heading = motion[titleAs];
  const boxSize = activities.length
    ? Math.max(...activities.map((activity) => activity.size))
    : 0;
  const inView = useInView(ref, { once: true, margin: "-40px" });
  const reduceMotion = useReducedMotion() ?? false;
  const [active, setActive] = useState<number | null>(null);
  // The legend's numbers, counted up by the ring that owns them.
  const countRefs = useRef<{ current: HTMLSpanElement | null }[]>([]);
  countRefs.current = activities.map(
    (_, index) => countRefs.current[index] ?? { current: null }
  );

  return (
    <div
      className={cn(
        "@container relative mx-auto w-full max-w-3xl rounded-3xl p-8",
        "text-zinc-900 dark:text-white",
        className
      )}
      ref={ref}
    >
      {/* Reduced motion keeps the fades and drops the scale/slide. */}
      <MotionConfig reducedMotion="user">
        <div className="flex flex-col items-center gap-8">
          <Heading
            animate={
              inView ? { opacity: 1, transform: "translateY(0px)" } : undefined
            }
            className="font-medium text-2xl text-zinc-900 dark:text-white"
            initial={{ opacity: 0, transform: "translateY(-12px)" }}
            transition={{ duration: 0.5, ease: EASE_OUT }}
          >
            {title}
          </Heading>

          <div className="flex @md:flex-row flex-col items-center gap-8">
            <div
              className="relative shrink-0"
              style={{ width: boxSize, height: boxSize }}
            >
              {activities.map((activity, index) => (
                <CircleProgress
                  countRef={countRefs.current[index]}
                  data={activity}
                  dimmed={active !== null && active !== index}
                  index={index}
                  inView={inView}
                  key={activity.label}
                  onActive={(on) =>
                    setActive((prev) => {
                      if (on) {
                        return index;
                      }
                      return prev === index ? null : prev;
                    })
                  }
                  reduceMotion={reduceMotion}
                />
              ))}
            </div>
            <DetailedActivityInfo
              active={active}
              activities={activities}
              countRefs={countRefs.current}
              inView={inView}
              onActive={setActive}
            />
          </div>
        </div>
      </MotionConfig>
    </div>
  );
}
```


---

# Widget Grid
> Dashboard widgets you lift, drag and resize on a 6-column grid, with spring physics and full keyboard support.

Source: https://kokonutui.com/docs/cards/bento-grid

## Installation

```bash
npx shadcn@latest add @kokonutui/bento-grid
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Widget Grid
 * @version: 3.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  Activity,
  GripVertical,
  HardDrive,
  History,
  NotebookPen,
  TrendingUp,
  Users,
} from "lucide-react";
import { AnimatePresence, motion } from "motion/react";
import {
  type CSSProperties,
  type FocusEvent,
  type KeyboardEvent,
  type MouseEvent,
  type ReactNode,
  type PointerEvent as ReactPointerEvent,
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

/* -------------------------------------------------------------------------- */
/*                                    Types                                   */
/* -------------------------------------------------------------------------- */

export type WidgetSize = "s" | "m" | "l";

export interface WidgetGridItem {
  id: string;
  title: string;
  icon?: ReactNode;
  /** Renders the widget body for the size its column span maps to. */
  render: (size: WidgetSize) => ReactNode;
  /** Span used when no layout is given. Defaults to 2. */
  defaultSpan?: number;
}

export interface WidgetLayoutItem {
  id: string;
  /** Width in columns of the 6-column grid (2 to 6). */
  span: number;
}

export interface WidgetGridProps {
  items?: WidgetGridItem[];
  /** Controlled order and spans. */
  layout?: WidgetLayoutItem[];
  /** Uncontrolled starting order and spans. */
  defaultLayout?: WidgetLayoutItem[];
  /** Called on every reorder or resize, including live moves while dragging. */
  onLayoutChange?: (layout: WidgetLayoutItem[]) => void;
  className?: string;
  /** Height of one row in pixels. */
  rowHeight?: number;
}

interface Rect {
  x: number;
  y: number;
  w: number;
  h: number;
}

interface DragState {
  id: string;
  mode: "pointer" | "keyboard";
  /** The pointer holding the cell; other fingers are ignored. */
  pointerId: number;
  grabX: number;
  grabY: number;
  lastX: number;
  lastY: number;
  lastT: number;
  skipId: string | null;
  snapshot: WidgetLayoutItem[];
}

interface PressState {
  id: string;
  pointerId: number;
  startX: number;
  startY: number;
  x: number;
  y: number;
  timer: number;
}

/* -------------------------------------------------------------------------- */
/*                                  Constants                                 */
/* -------------------------------------------------------------------------- */

const COLUMNS = 6;
const NARROW_COLUMNS = 2;
const MIN_SPAN = 2;
const GAP = 12;
/** Matches the `@xl/wg` container query (36rem). */
const NARROW_BELOW = 576;
const LONG_PRESS_MS = 350;
const PRESS_SLOP = 8;
const LIFT_Z = 18;
const MAX_TILT = 7;
const SIZE_LABEL: Record<WidgetSize, string> = {
  s: "small",
  m: "medium",
  l: "large",
};

/** Maps a column span to the widget layout it shows. */
export function sizeForSpan(span: number, narrow = false): WidgetSize {
  if (narrow) {
    return span <= MIN_SPAN ? "s" : "m";
  }
  if (span <= 2) {
    return "s";
  }
  return span <= 4 ? "m" : "l";
}

function clampSpan(span: number) {
  return Math.min(COLUMNS, Math.max(MIN_SPAN, Math.round(span)));
}

/** In the 2-column layout, small widgets take one column, the rest both. */
function narrowSpan(span: number) {
  return span <= MIN_SPAN ? 1 : 2;
}

function normalizeLayout(
  layout: WidgetLayoutItem[],
  items: WidgetGridItem[]
): WidgetLayoutItem[] {
  const known = new Set(items.map((item) => item.id));
  const seen = new Set<string>();
  const out: WidgetLayoutItem[] = [];
  for (const entry of layout) {
    if (known.has(entry.id) && !seen.has(entry.id)) {
      seen.add(entry.id);
      out.push({ id: entry.id, span: clampSpan(entry.span) });
    }
  }
  for (const item of items) {
    if (!seen.has(item.id)) {
      out.push({ id: item.id, span: clampSpan(item.defaultSpan ?? MIN_SPAN) });
    }
  }
  return out;
}

function moveItem<T>(list: T[], from: number, to: number): T[] {
  const next = list.slice();
  const [moved] = next.splice(from, 1);
  next.splice(to, 0, moved);
  return next;
}

function contains(rect: Rect, x: number, y: number) {
  return (
    x >= rect.x && x <= rect.x + rect.w && y >= rect.y && y <= rect.y + rect.h
  );
}

/* -------------------------------------------------------------------------- */
/*                               Spring physics                               */
/* -------------------------------------------------------------------------- */

interface SpringConfig {
  k: number;
  c: number;
}

const spring = (k: number, zeta: number): SpringConfig => ({
  k,
  c: 2 * Math.sqrt(k) * zeta,
});

const MOVE_SPRING = spring(420, 0.76);
const LIFT_SPRING = spring(520, 0.82);
const TILT_SPRING = spring(260, 0.6);
const STEP = 1 / 120;

interface Body {
  ox: number;
  oy: number;
  vx: number;
  vy: number;
  sx: number;
  sy: number;
  vsx: number;
  vsy: number;
  lift: number;
  vlift: number;
  liftTarget: number;
  rx: number;
  ry: number;
  vrx: number;
  vry: number;
  /** Smoothed pointer velocity (px/ms) while pinned to the pointer. */
  pvx: number;
  pvy: number;
  /** Seconds to wait before springing home (distance stagger). */
  hold: number;
  /** Follows the pointer directly instead of springing home. */
  pinned: boolean;
}

function createBody(): Body {
  return {
    ox: 0,
    oy: 0,
    vx: 0,
    vy: 0,
    sx: 1,
    sy: 1,
    vsx: 0,
    vsy: 0,
    lift: 0,
    vlift: 0,
    liftTarget: 0,
    rx: 0,
    ry: 0,
    vrx: 0,
    vry: 0,
    pvx: 0,
    pvy: 0,
    hold: 0,
    pinned: false,
  };
}

/** One semi-implicit Euler step; returns [position, velocity]. */
function integrate(
  x: number,
  v: number,
  target: number,
  cfg: SpringConfig,
  dt: number
): [number, number] {
  const a = -cfg.k * (x - target) - cfg.c * v;
  const nv = v + a * dt;
  return [x + nv * dt, nv];
}

const clampTilt = (v: number) => Math.max(-MAX_TILT, Math.min(MAX_TILT, v));

function stepBody(b: Body, dt: number) {
  // Lean toward the drag direction: right edge dips when moving right.
  const tiltY = b.pinned ? clampTilt(b.pvx * 9) : 0;
  const tiltX = b.pinned ? clampTilt(-b.pvy * 9) : 0;
  [b.ry, b.vry] = integrate(b.ry, b.vry, tiltY, TILT_SPRING, dt);
  [b.rx, b.vrx] = integrate(b.rx, b.vrx, tiltX, TILT_SPRING, dt);
  [b.lift, b.vlift] = integrate(b.lift, b.vlift, b.liftTarget, LIFT_SPRING, dt);
  // Pointer velocity decays when the pointer rests, so the tilt settles.
  b.pvx *= Math.exp(-dt * 10);
  b.pvy *= Math.exp(-dt * 10);
  if (b.hold > 0) {
    b.hold -= dt;
    return;
  }
  if (!b.pinned) {
    [b.ox, b.vx] = integrate(b.ox, b.vx, 0, MOVE_SPRING, dt);
    [b.oy, b.vy] = integrate(b.oy, b.vy, 0, MOVE_SPRING, dt);
  }
  [b.sx, b.vsx] = integrate(b.sx, b.vsx, 1, MOVE_SPRING, dt);
  [b.sy, b.vsy] = integrate(b.sy, b.vsy, 1, MOVE_SPRING, dt);
}

const near = (x: number, v: number, target: number, eps: number) =>
  Math.abs(x - target) < eps && Math.abs(v) < eps * 10;

function isSettled(b: Body) {
  if (b.pinned || b.hold > 0) {
    return false;
  }
  return (
    near(b.ox, b.vx, 0, 0.2) &&
    near(b.oy, b.vy, 0, 0.2) &&
    near(b.sx, b.vsx, 1, 0.001) &&
    near(b.sy, b.vsy, 1, 0.001) &&
    near(b.lift, b.vlift, b.liftTarget, 0.002) &&
    near(b.rx, b.vrx, 0, 0.02) &&
    near(b.ry, b.vry, 0, 0.02)
  );
}

function snapBody(b: Body) {
  if (!b.pinned) {
    b.ox = 0;
    b.oy = 0;
  }
  b.vx = 0;
  b.vy = 0;
  b.sx = 1;
  b.sy = 1;
  b.vsx = 0;
  b.vsy = 0;
  b.lift = b.liftTarget;
  b.vlift = 0;
  b.rx = 0;
  b.ry = 0;
  b.vrx = 0;
  b.vry = 0;
  b.hold = 0;
}

const r2 = (n: number) => Math.round(n * 100) / 100;
const r3 = (n: number) => Math.round(n * 1000) / 1000;

/**
 * Owns every cell's spring state and writes transforms straight to the DOM,
 * so React never re-renders per frame. The loop sleeps once all is settled.
 */
class GridEngine {
  bodies = new Map<string, Body>();
  els = new Map<string, HTMLElement>();
  reduced = false;
  private raf = 0;
  private last = 0;

  body(id: string) {
    let b = this.bodies.get(id);
    if (!b) {
      b = createBody();
      this.bodies.set(id, b);
    }
    return b;
  }

  kick() {
    if (this.raf || typeof window === "undefined") {
      return;
    }
    this.last = performance.now();
    this.raf = requestAnimationFrame(this.tick);
  }

  stop() {
    cancelAnimationFrame(this.raf);
    this.raf = 0;
  }

  write(id: string, b: Body) {
    const el = this.els.get(id);
    if (!el) {
      return;
    }
    const surface = el.firstElementChild as HTMLElement | null;
    const shadow = surface?.firstElementChild as HTMLElement | null;
    const atRest =
      b.ox === 0 && b.oy === 0 && b.lift === 0 && b.rx === 0 && b.ry === 0;
    el.style.transform = atRest
      ? ""
      : `translate3d(${r2(b.ox)}px, ${r2(b.oy)}px, ${r2(b.lift * LIFT_Z)}px) rotateX(${r2(b.rx)}deg) rotateY(${r2(b.ry)}deg)`;
    if (surface) {
      surface.style.transform =
        b.sx === 1 && b.sy === 1 ? "" : `scale(${r3(b.sx)}, ${r3(b.sy)})`;
    }
    if (shadow) {
      shadow.style.opacity = String(r2(Math.max(0, Math.min(1, b.lift))));
    }
  }

  private advance(b: Body, elapsed: number) {
    if (this.reduced) {
      snapBody(b);
      return false;
    }
    let t = elapsed;
    while (t > 0) {
      const dt = Math.min(STEP, t);
      stepBody(b, dt);
      t -= dt;
    }
    if (isSettled(b)) {
      snapBody(b);
      return false;
    }
    return true;
  }

  private readonly tick = (now: number) => {
    const elapsed = Math.min(0.05, (now - this.last) / 1000);
    this.last = now;
    let active = false;
    for (const [id, b] of this.bodies) {
      active = this.advance(b, elapsed) || active;
      this.write(id, b);
    }
    this.raf = active ? requestAnimationFrame(this.tick) : 0;
  };
}

/* -------------------------------------------------------------------------- */
/*                                 Demo widgets                               */
/* -------------------------------------------------------------------------- */

const VALUE =
  "font-semibold text-zinc-900 tabular-nums tracking-tight dark:text-zinc-50";
const MUTED = "text-zinc-500 dark:text-zinc-400";
const ACCENT_TEXT = "font-medium text-(--wg-accent)";

const REVENUE_SERIES = [
  31, 34, 33, 36, 35, 39, 38, 41, 40, 43, 42, 45, 44, 48,
] as const;
const SPARK_POINTS = REVENUE_SERIES.map((v, i) => {
  const x = Math.round((i / (REVENUE_SERIES.length - 1)) * 1000) / 10;
  const y = Math.round((1 - (v - 30) / 19) * 300) / 10 + 1;
  return `${x},${y}`;
}).join(" ");

function Sparkline() {
  return (
    <svg
      aria-hidden="true"
      className="h-10 w-full overflow-visible"
      preserveAspectRatio="none"
      viewBox="0 0 100 32"
    >
      <polyline
        fill="none"
        points={SPARK_POINTS}
        stroke="var(--wg-accent)"
        strokeLinecap="round"
        strokeLinejoin="round"
        strokeWidth={1.75}
        vectorEffect="non-scaling-stroke"
      />
    </svg>
  );
}

const REVENUE_ROWS = [
  ["New", "$6,140"],
  ["Expansion", "$2,380"],
  ["Churned", "−$1,190"],
] as const;

function RevenueWidget({ size }: { size: WidgetSize }) {
  const head = (
    <div>
      <p className={cn(VALUE, size === "s" ? "text-2xl" : "text-3xl")}>
        $48,210
      </p>
      <p className="mt-1 text-xs">
        <span className={ACCENT_TEXT}>+12.4%</span>
        <span className={MUTED}> vs last month</span>
      </p>
    </div>
  );
  if (size === "s") {
    return <div className="flex h-full flex-col justify-end">{head}</div>;
  }
  if (size === "m") {
    return (
      <div className="flex h-full flex-col justify-between gap-2">
        {head}
        <Sparkline />
      </div>
    );
  }
  return (
    <div className="grid h-full grid-cols-[1.4fr_1fr] gap-6">
      <div className="flex min-w-0 flex-col justify-between gap-2">
        {head}
        <Sparkline />
      </div>
      <dl className="flex flex-col justify-end gap-1.5 text-xs">
        {REVENUE_ROWS.map(([label, value]) => (
          <div
            className="flex items-baseline justify-between border-zinc-100 border-b pb-1.5 last:border-0 last:pb-0 dark:border-zinc-800"
            key={label}
          >
            <dt className={MUTED}>{label}</dt>
            <dd className="font-medium text-zinc-800 tabular-nums dark:text-zinc-200">
              {value}
            </dd>
          </div>
        ))}
      </dl>
    </div>
  );
}

const USERS_SERIES = [
  1820, 1960, 2010, 1890, 2240, 1450, 1380, 2120, 2380, 2290, 2510, 2640, 1720,
  2841,
] as const;
const DAY_LABELS = ["M", "T", "W", "T", "F", "S", "S"] as const;
const BAR_KEYS = USERS_SERIES.map((_, i) => `d${i}`);

function Bars({
  values,
  labels,
}: {
  values: readonly number[];
  labels: readonly string[];
}) {
  const max = Math.max(...values);
  const keys = BAR_KEYS.slice(-values.length);
  return (
    <div className="flex h-full min-h-0 flex-col gap-1">
      <div className="flex min-h-0 flex-1 items-end gap-1">
        {values.map((v, i) => (
          <div
            className={cn(
              "flex-1 rounded-[3px]",
              i === values.length - 1
                ? "bg-(--wg-accent)"
                : "bg-zinc-200 dark:bg-zinc-800"
            )}
            key={keys[i]}
            style={{ height: `${Math.round((v / max) * 100)}%` }}
          />
        ))}
      </div>
      <div className="flex gap-1">
        {labels.map((label, i) => (
          <span
            className={cn(MUTED, "flex-1 text-center text-[10px] leading-3")}
            key={keys[i]}
          >
            {label}
          </span>
        ))}
      </div>
    </div>
  );
}

function UsersWidget({ size }: { size: WidgetSize }) {
  if (size === "s") {
    return (
      <div className="flex h-full flex-col justify-end gap-1">
        <p className={cn(VALUE, "text-2xl")}>2,841</p>
        <p className="text-xs">
          <span className={ACCENT_TEXT}>+6.2%</span>
          <span className={MUTED}> today</span>
        </p>
      </div>
    );
  }
  return (
    <div className="flex h-full flex-col gap-3">
      <div className="flex items-baseline gap-2">
        <p className={cn(VALUE, "text-2xl")}>2,841</p>
        <p className="text-xs">
          <span className={ACCENT_TEXT}>+6.2%</span>
          <span className={MUTED}> active today</span>
        </p>
      </div>
      <div className="min-h-0 flex-1">
        {size === "m" ? (
          <Bars labels={DAY_LABELS} values={USERS_SERIES.slice(-7)} />
        ) : (
          <Bars labels={[...DAY_LABELS, ...DAY_LABELS]} values={USERS_SERIES} />
        )}
      </div>
    </div>
  );
}

const EVENTS = [
  { time: "09:41", text: "Release 4.2 promoted to production" },
  { time: "09:12", text: "Invoice 2041 paid" },
  { time: "08:55", text: "New teammate joined Design" },
  { time: "Mon", text: "Nightly backup verified" },
] as const;

const EVENT_COUNT: Record<WidgetSize, number> = { s: 1, m: 3, l: 4 };

function TimelineWidget({ size }: { size: WidgetSize }) {
  const count = EVENT_COUNT[size];
  return (
    <ol className="flex h-full flex-col justify-end">
      {EVENTS.slice(0, count).map((event, i) => (
        <li className="relative flex gap-3 pb-2 last:pb-0" key={event.text}>
          <span className="relative flex w-2 shrink-0 justify-center pt-1.5">
            <span
              className={cn(
                "size-2 rounded-full",
                i === 0
                  ? "bg-(--wg-accent)"
                  : "border border-zinc-300 bg-white dark:border-zinc-600 dark:bg-zinc-900"
              )}
            />
            {i < count - 1 ? (
              <span className="absolute top-4 bottom-[-6px] w-px bg-zinc-200 dark:bg-zinc-800" />
            ) : null}
          </span>
          <span className="min-w-0 flex-1 text-xs leading-5">
            <span className="block truncate text-zinc-800 dark:text-zinc-200">
              {event.text}
            </span>
            {size === "s" ? (
              <span className={MUTED}>Today, {event.time}</span>
            ) : null}
          </span>
          {size === "s" ? null : (
            <span
              className={cn(MUTED, "shrink-0 text-xs tabular-nums leading-5")}
            >
              {event.time}
            </span>
          )}
        </li>
      ))}
    </ol>
  );
}

const NOTES = [
  { text: "Draft Q4 roadmap", done: true },
  { text: "Review onboarding copy", done: true },
  { text: "Pick pricing experiment", done: true },
  { text: "Book design review", done: false },
  { text: "Share hiring plan", done: false },
] as const;
const NOTES_DONE = NOTES.filter((note) => note.done).length;

function Check({ done }: { done: boolean }) {
  return (
    <span
      className={cn(
        "flex size-3.5 shrink-0 items-center justify-center rounded-[4px] border",
        done
          ? "border-(--wg-accent) bg-(--wg-accent) text-white dark:text-zinc-950"
          : "border-zinc-300 dark:border-zinc-600"
      )}
    >
      {done ? (
        <svg
          aria-hidden="true"
          className="size-2.5"
          fill="none"
          viewBox="0 0 10 10"
        >
          <path
            d="M2 5.2 4.1 7.2 8 3"
            stroke="currentColor"
            strokeLinecap="round"
            strokeLinejoin="round"
            strokeWidth={1.6}
          />
        </svg>
      ) : null}
    </span>
  );
}

function NotesWidget({ size }: { size: WidgetSize }) {
  if (size === "s") {
    return (
      <div className="flex h-full flex-col justify-end gap-2">
        <p className="font-medium text-sm text-zinc-900 dark:text-zinc-100">
          Q4 planning
        </p>
        <p className={cn(MUTED, "text-xs")}>
          {NOTES_DONE} of {NOTES.length} done
        </p>
        <div className="h-1 overflow-hidden rounded-full bg-zinc-100 dark:bg-zinc-800">
          <div
            className="h-full rounded-full bg-(--wg-accent)"
            style={{ width: `${(NOTES_DONE / NOTES.length) * 100}%` }}
          />
        </div>
      </div>
    );
  }
  const list = size === "m" ? NOTES.slice(2) : NOTES;
  return (
    <ul
      className={cn(
        "grid h-full content-end gap-x-6 gap-y-2 text-xs",
        size === "l" && "grid-cols-2"
      )}
    >
      {list.map((note) => (
        <li className="flex min-w-0 items-center gap-2" key={note.text}>
          <Check done={note.done} />
          <span
            className={cn(
              "truncate",
              note.done
                ? "text-zinc-400 line-through dark:text-zinc-500"
                : "text-zinc-800 dark:text-zinc-200"
            )}
          >
            {note.text}
          </span>
        </li>
      ))}
    </ul>
  );
}

const UPTIME_INCIDENT_AGO = 18;
const TICK_KEYS = Array.from({ length: 45 }, (_, i) => `t${i}`);

function UptimeWidget({ size }: { size: WidgetSize }) {
  const ticks = size === "l" ? 45 : 30;
  return (
    <div className="flex h-full flex-col justify-end gap-3">
      <div className="flex items-baseline gap-2">
        <p className={cn(VALUE, "text-2xl")}>99.98%</p>
        {size === "s" ? null : (
          <p className={cn(MUTED, "text-xs")}>last {ticks} days</p>
        )}
      </div>
      {size === "s" ? (
        <p className={cn(MUTED, "text-xs")}>All systems normal</p>
      ) : (
        <div className="flex h-7 gap-[3px]">
          {TICK_KEYS.slice(0, ticks).map((key, i) => (
            <span
              className={cn(
                "flex-1 rounded-[2px]",
                i === ticks - UPTIME_INCIDENT_AGO
                  ? "bg-(--wg-accent)"
                  : "bg-zinc-200 dark:bg-zinc-800"
              )}
              key={key}
            />
          ))}
        </div>
      )}
      {size === "l" ? (
        <p className={cn(MUTED, "text-xs")}>
          One incident {UPTIME_INCIDENT_AGO} days ago: slower API responses for
          4 minutes.
        </p>
      ) : null}
    </div>
  );
}

const STORAGE = [
  { label: "Media", gb: 182, tone: "bg-(--wg-accent)" },
  { label: "Documents", gb: 96, tone: "bg-zinc-500 dark:bg-zinc-400" },
  { label: "Backups", gb: 64, tone: "bg-zinc-300 dark:bg-zinc-600" },
] as const;
const STORAGE_TOTAL = 500;
const STORAGE_USED = STORAGE.reduce((sum, s) => sum + s.gb, 0);

function StorageWidget({ size }: { size: WidgetSize }) {
  const segments =
    size === "s"
      ? [{ label: "Used", gb: STORAGE_USED, tone: "bg-(--wg-accent)" }]
      : STORAGE;
  return (
    <div className="flex h-full flex-col justify-end gap-2.5">
      <p className="flex items-baseline gap-1.5">
        <span className={cn(VALUE, "text-2xl")}>{STORAGE_USED} GB</span>
        <span className={cn(MUTED, "text-xs")}>of {STORAGE_TOTAL}</span>
      </p>
      <div className="flex h-1.5 gap-px overflow-hidden rounded-full bg-zinc-100 dark:bg-zinc-800">
        {segments.map((s) => (
          <span
            className={cn("h-full", s.tone)}
            key={s.label}
            style={{ width: `${(s.gb / STORAGE_TOTAL) * 100}%` }}
          />
        ))}
      </div>
      {size === "s" ? null : (
        <ul className="flex flex-wrap gap-x-4 gap-y-1 text-xs">
          {STORAGE.map((s) => (
            <li className="flex items-center gap-1.5" key={s.label}>
              <span className={cn("size-2 rounded-full", s.tone)} />
              <span className={MUTED}>{s.label}</span>
              {size === "l" ? (
                <span className="text-zinc-800 tabular-nums dark:text-zinc-200">
                  {s.gb} GB
                </span>
              ) : null}
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}

const ICON = "size-3.5";

export const DEMO_WIDGETS: WidgetGridItem[] = [
  {
    id: "revenue",
    title: "Revenue",
    icon: <TrendingUp className={ICON} />,
    defaultSpan: 2,
    render: (size) => <RevenueWidget size={size} />,
  },
  {
    id: "users",
    title: "Active users",
    icon: <Users className={ICON} />,
    defaultSpan: 4,
    render: (size) => <UsersWidget size={size} />,
  },
  {
    id: "activity",
    title: "Activity",
    icon: <History className={ICON} />,
    defaultSpan: 3,
    render: (size) => <TimelineWidget size={size} />,
  },
  {
    id: "notes",
    title: "Notes",
    icon: <NotebookPen className={ICON} />,
    defaultSpan: 3,
    render: (size) => <NotesWidget size={size} />,
  },
  {
    id: "uptime",
    title: "Uptime",
    icon: <Activity className={ICON} />,
    defaultSpan: 4,
    render: (size) => <UptimeWidget size={size} />,
  },
  {
    id: "storage",
    title: "Storage",
    icon: <HardDrive className={ICON} />,
    defaultSpan: 2,
    render: (size) => <StorageWidget size={size} />,
  },
];

/* -------------------------------------------------------------------------- */
/*                                    Cell                                    */
/* -------------------------------------------------------------------------- */

interface CellProps {
  item: WidgetGridItem;
  span: number;
  narrow: boolean;
  lifted: boolean;
  dimmed: boolean;
  instructionsId: string;
  cellRef: (el: HTMLDivElement | null) => void;
  gripRef: (el: HTMLButtonElement | null) => void;
  onPressStart: (e: ReactPointerEvent<HTMLDivElement>) => void;
  onGripPointerDown: (e: ReactPointerEvent<HTMLButtonElement>) => void;
  onGripKeyDown: (e: KeyboardEvent<HTMLButtonElement>) => void;
  onGripBlur: () => void;
  onResizePointerDown: (e: ReactPointerEvent<HTMLButtonElement>) => void;
  onResizeKeyDown: (e: KeyboardEvent<HTMLButtonElement>) => void;
  onHover: (on: boolean) => void;
  onFocusChange: (on: boolean) => void;
}

function WidgetCell({
  item,
  span,
  narrow,
  lifted,
  dimmed,
  instructionsId,
  cellRef,
  gripRef,
  onPressStart,
  onGripPointerDown,
  onGripKeyDown,
  onGripBlur,
  onResizePointerDown,
  onResizeKeyDown,
  onHover,
  onFocusChange,
}: CellProps) {
  const size = sizeForSpan(span, narrow);
  const columns = narrow ? NARROW_COLUMNS : COLUMNS;
  const shownSpan = narrow ? narrowSpan(span) : span;

  const handleFocus = (e: FocusEvent<HTMLDivElement>) => {
    if (e.target.matches(":focus-visible")) {
      onFocusChange(true);
    }
  };
  const handleBlur = (e: FocusEvent<HTMLDivElement>) => {
    if (!e.currentTarget.contains(e.relatedTarget as Node | null)) {
      onFocusChange(false);
    }
  };
  // Long-pressing with a finger would otherwise open the system menu.
  const handleContextMenu = (e: MouseEvent<HTMLDivElement>) => {
    const native = e.nativeEvent as globalThis.PointerEvent;
    if (lifted || native.pointerType === "touch") {
      e.preventDefault();
    }
  };

  return (
    // biome-ignore lint/a11y/noStaticElementInteractions: long press is a pointer shortcut; the grip button is the accessible control.
    // biome-ignore lint/a11y/noNoninteractiveElementInteractions: long press is a pointer shortcut; the grip button is the accessible control.
    <div
      className={cn(
        "group/cell relative @xl/wg:col-span-(--span) col-span-(--span-n) select-none [-webkit-touch-callout:none]",
        "transition-opacity duration-200 ease-out",
        dimmed && "opacity-45",
        lifted && "z-20"
      )}
      data-lifted={lifted || undefined}
      onBlur={handleBlur}
      onContextMenu={handleContextMenu}
      onFocus={handleFocus}
      onPointerDown={onPressStart}
      onPointerEnter={(e) => e.pointerType === "mouse" && onHover(true)}
      onPointerLeave={(e) => e.pointerType === "mouse" && onHover(false)}
      ref={cellRef}
      style={{ "--span": span, "--span-n": narrowSpan(span) } as CSSProperties}
    >
      {/* Surface: scaled by the engine while a resize settles. */}
      <div className="pointer-events-none absolute inset-0 origin-top-left rounded-2xl border border-zinc-200 bg-white transition-colors duration-200 group-data-lifted/cell:border-zinc-300 dark:border-zinc-800 dark:bg-zinc-900 dark:group-data-lifted/cell:border-zinc-700">
        {/* Lift shadow, faded in by the engine. */}
        <div className="absolute inset-0 rounded-2xl opacity-0 shadow-[0_24px_48px_-16px_rgb(0_0_0/0.22),0_8px_16px_-8px_rgb(0_0_0/0.12)] dark:shadow-[0_24px_48px_-12px_rgb(0_0_0/0.7),0_8px_16px_-8px_rgb(0_0_0/0.5)]" />
      </div>

      <div className="relative flex h-full flex-col p-4 pt-3">
        <div className="mb-2 flex h-7 shrink-0 items-center gap-2">
          <span aria-hidden className="text-zinc-400 dark:text-zinc-500">
            {item.icon}
          </span>
          <span className="truncate font-medium text-[13px] text-zinc-600 dark:text-zinc-400">
            {item.title}
          </span>
          <button
            aria-describedby={instructionsId}
            aria-label={`Move ${item.title} (${SIZE_LABEL[size]})`}
            aria-pressed={lifted}
            className={cn(
              "-mr-2 ml-auto flex size-7 shrink-0 cursor-grab touch-none items-center justify-center rounded-md text-zinc-400 outline-none",
              "transition-colors duration-150 hover:bg-zinc-100 hover:text-zinc-700 dark:text-zinc-500 dark:hover:bg-zinc-800 dark:hover:text-zinc-200",
              "focus-visible:ring-(--wg-accent) focus-visible:ring-2",
              lifted &&
                "cursor-grabbing bg-zinc-100 text-zinc-700 dark:bg-zinc-800 dark:text-zinc-200"
            )}
            data-no-press
            onBlur={onGripBlur}
            onKeyDown={onGripKeyDown}
            onPointerDown={onGripPointerDown}
            ref={gripRef}
            type="button"
          >
            <GripVertical aria-hidden className="size-4" />
          </button>
        </div>

        <div className="relative min-h-0 flex-1">
          <AnimatePresence initial={false}>
            <motion.div
              animate={{ opacity: 1 }}
              className="absolute inset-0"
              exit={{ opacity: 0 }}
              initial={{ opacity: 0 }}
              key={size}
              transition={{ duration: 0.22, ease: [0.23, 1, 0.32, 1] }}
            >
              {item.render(size)}
            </motion.div>
          </AnimatePresence>
        </div>
      </div>

      <button
        aria-label={`Resize ${item.title}, ${shownSpan} of ${columns} columns`}
        className={cn(
          "absolute right-0 bottom-0 flex size-7 cursor-ew-resize touch-none items-end justify-end rounded-br-2xl p-1.5 text-zinc-400 outline-none dark:text-zinc-500",
          "opacity-0 transition-opacity duration-150 focus-visible:opacity-100 group-hover/cell:opacity-100 [@media(hover:none)]:opacity-70",
          "hover:text-zinc-700 focus-visible:text-(--wg-accent) dark:hover:text-zinc-200"
        )}
        data-no-press
        onKeyDown={onResizeKeyDown}
        onPointerDown={onResizePointerDown}
        type="button"
      >
        <svg
          aria-hidden="true"
          className="size-2.5"
          fill="none"
          viewBox="0 0 10 10"
        >
          <path
            d="M9 3 3 9M9 6.5 6.5 9"
            stroke="currentColor"
            strokeLinecap="round"
            strokeWidth={1.5}
          />
        </svg>
      </button>
    </div>
  );
}

/* -------------------------------------------------------------------------- */
/*                                 Widget Grid                                */
/* -------------------------------------------------------------------------- */

export default function WidgetGrid({
  items = DEMO_WIDGETS,
  layout,
  defaultLayout,
  onLayoutChange,
  className,
  rowHeight = 176,
}: WidgetGridProps) {
  const instructionsId = useId();
  const [innerLayout, setInnerLayout] = useState<WidgetLayoutItem[]>(() =>
    normalizeLayout(defaultLayout ?? [], items)
  );
  const current = useMemo(
    () => normalizeLayout(layout ?? innerLayout, items),
    [layout, innerLayout, items]
  );
  const layoutKey = current.map((c) => `${c.id}:${c.span}`).join("|");
  const itemsById = useMemo(
    () => new Map(items.map((item) => [item.id, item])),
    [items]
  );

  const [narrow, setNarrow] = useState(false);
  const [liftedId, setLiftedId] = useState<string | null>(null);
  const [resizingId, setResizingId] = useState<string | null>(null);
  // Last cell hovered or keyboard-focused; it stays lit while others dim.
  const [pointedId, setPointedId] = useState<string | null>(null);
  const [message, setMessage] = useState("");

  const wrapRef = useRef<HTMLDivElement>(null);
  const gridRef = useRef<HTMLDivElement>(null);
  const engineRef = useRef<GridEngine | null>(null);
  if (!engineRef.current) {
    engineRef.current = new GridEngine();
  }
  const engine = engineRef.current;
  const rectsRef = useRef(new Map<string, Rect>());
  const gripsRef = useRef(new Map<string, HTMLButtonElement>());
  const pendingFlipRef = useRef<{
    prev: Map<string, Rect>;
    movedId: string;
  } | null>(null);
  const dragRef = useRef<DragState | null>(null);
  const pressRef = useRef<PressState | null>(null);
  const resizeIdRef = useRef<string | null>(null);
  const resizeStartRef = useRef<{ x: number; span: number } | null>(null);
  const reorderingRef = useRef(false);
  const narrowRef = useRef(false);
  const layoutRef = useRef(current);
  layoutRef.current = current;
  const latest = useRef({ layout, onLayoutChange, itemsById });
  latest.current = { layout, onLayoutChange, itemsById };
  // Stable handles to handlers that are declared further down.
  const cancelPressRef = useRef<() => void>(() => undefined);
  const endDragRef = useRef<(cancel: boolean) => void>(() => undefined);

  const titleOf = useCallback(
    (id: string) => latest.current.itemsById.get(id)?.title ?? id,
    []
  );

  const announce = useCallback((text: string) => {
    // A trailing space makes a repeated message read again.
    setMessage((prev) => (prev === text ? `${text} ` : text));
  }, []);

  const positionText = useCallback((id: string) => {
    const list = layoutRef.current;
    const index = list.findIndex((c) => c.id === id);
    return `position ${index + 1} of ${list.length}`;
  }, []);

  const commit = useCallback((next: WidgetLayoutItem[], movedId: string) => {
    pendingFlipRef.current = { prev: new Map(rectsRef.current), movedId };
    layoutRef.current = next;
    if (latest.current.layout === undefined) {
      setInnerLayout(next);
    }
    latest.current.onLayoutChange?.(next);
  }, []);

  /* ------------------------------ measuring ------------------------------ */

  // offset* ignore transforms, so these are the cells' resting slots.
  const measure = useCallback(() => {
    const next = new Map<string, Rect>();
    for (const [id, el] of engine.els) {
      next.set(id, {
        x: el.offsetLeft,
        y: el.offsetTop,
        w: el.offsetWidth,
        h: el.offsetHeight,
      });
    }
    rectsRef.current = next;
    return next;
  }, [engine]);

  const toGrid = useCallback((clientX: number, clientY: number) => {
    const box = gridRef.current?.getBoundingClientRect();
    return { x: clientX - (box?.left ?? 0), y: clientY - (box?.top ?? 0) };
  }, []);

  /** Keeps a pointer-held cell under the pointer, even after its slot moved. */
  const placeDragged = useCallback(() => {
    const drag = dragRef.current;
    const rect = drag ? rectsRef.current.get(drag.id) : undefined;
    if (!(drag && rect) || drag.mode !== "pointer") {
      return;
    }
    const p = toGrid(drag.lastX, drag.lastY);
    const b = engine.body(drag.id);
    b.ox = p.x - drag.grabX - rect.x;
    b.oy = p.y - drag.grabY - rect.y;
    engine.write(drag.id, b);
    engine.kick();
  }, [engine, toGrid]);

  /** FLIP: start every moved cell where it was drawn, then spring it home. */
  const flip = useCallback(
    (prev: Map<string, Rect>, next: Map<string, Rect>, movedId: string) => {
      const origin = next.get(movedId);
      const cx = origin ? origin.x + origin.w / 2 : 0;
      const cy = origin ? origin.y + origin.h / 2 : 0;
      const pinnedId =
        dragRef.current?.mode === "pointer" ? dragRef.current.id : null;
      for (const [id, n] of next) {
        const p = prev.get(id);
        if (!p || id === pinnedId) {
          continue;
        }
        const b = engine.body(id);
        const moved =
          Math.abs(p.x - n.x) > 0.5 || Math.abs(p.y - n.y) > 0.5 || p.w !== n.w;
        b.ox += p.x - n.x;
        b.oy += p.y - n.y;
        b.sx = (p.w * b.sx) / n.w;
        b.sy = (p.h * b.sy) / n.h;
        if (moved && id !== movedId) {
          // Nearer neighbours leave first, so the shuffle ripples outward.
          const dist = Math.hypot(n.x + n.w / 2 - cx, n.y + n.h / 2 - cy);
          b.hold = Math.min(0.1, dist * 0.000_16);
        }
        engine.write(id, b);
      }
      engine.kick();
    },
    [engine]
  );

  // After every layout change: measure, FLIP neighbours, re-seat the held cell.
  // biome-ignore lint/correctness/useExhaustiveDependencies: layoutKey and narrow are the triggers.
  useLayoutEffect(() => {
    const next = measure();
    const pending = pendingFlipRef.current;
    pendingFlipRef.current = null;
    if (pending) {
      flip(pending.prev, next, pending.movedId);
    }
    placeDragged();
    const drag = dragRef.current;
    if (drag?.mode === "keyboard") {
      // React may move the focused node when it reorders; keep focus on it.
      const grip = gripsRef.current.get(drag.id);
      if (grip && document.activeElement !== grip) {
        grip.focus({ preventScroll: true });
      }
    }
    reorderingRef.current = false;
  }, [layoutKey, narrow, measure, flip, placeDragged]);

  // Container width decides the 2- or 6-column layout; re-measure on resize.
  useEffect(() => {
    const wrap = wrapRef.current;
    if (!wrap) {
      return;
    }
    const ro = new ResizeObserver(() => {
      const isNarrow = wrap.clientWidth < NARROW_BELOW;
      narrowRef.current = isNarrow;
      setNarrow(isNarrow);
      measure();
      placeDragged();
    });
    ro.observe(wrap);
    return () => ro.disconnect();
  }, [measure, placeDragged]);

  // Reduced motion is read after mount, so it never changes the first render.
  useEffect(() => {
    const mq = window.matchMedia("(prefers-reduced-motion: reduce)");
    const sync = () => {
      engine.reduced = mq.matches;
    };
    sync();
    mq.addEventListener("change", sync);
    return () => mq.removeEventListener("change", sync);
  }, [engine]);

  /* ------------------------------ pointer drag ---------------------------- */

  const hitTest = useCallback(
    (x: number, y: number) => {
      const drag = dragRef.current;
      if (!drag) {
        return;
      }
      // Ignore the cell just swapped with until the pointer leaves it, so
      // cells of different widths don't flip back and forth.
      if (drag.skipId) {
        const skipRect = rectsRef.current.get(drag.skipId);
        if (skipRect && contains(skipRect, x, y)) {
          return;
        }
        drag.skipId = null;
      }
      const list = layoutRef.current;
      const from = list.findIndex((c) => c.id === drag.id);
      const to = list.findIndex((c) => {
        const rect = rectsRef.current.get(c.id);
        return c.id !== drag.id && rect !== undefined && contains(rect, x, y);
      });
      if (to < 0) {
        return;
      }
      drag.skipId = list[to].id;
      commit(moveItem(list, from, to), drag.id);
      announce(
        `${titleOf(drag.id)} moved to position ${to + 1} of ${list.length}.`
      );
    },
    [announce, commit, titleOf]
  );

  const onDragMove = useCallback(
    (e: globalThis.PointerEvent) => {
      const drag = dragRef.current;
      if (!drag || drag.mode !== "pointer" || e.pointerId !== drag.pointerId) {
        return;
      }
      const now = performance.now();
      const dt = Math.max(1, now - drag.lastT);
      const b = engine.body(drag.id);
      b.pvx += ((e.clientX - drag.lastX) / dt - b.pvx) * 0.35;
      b.pvy += ((e.clientY - drag.lastY) / dt - b.pvy) * 0.35;
      drag.lastX = e.clientX;
      drag.lastY = e.clientY;
      drag.lastT = now;
      placeDragged();
      const p = toGrid(e.clientX, e.clientY);
      hitTest(p.x, p.y);
    },
    [engine, hitTest, placeDragged, toGrid]
  );

  const onDragUp = useCallback((e: globalThis.PointerEvent) => {
    if (e.pointerId === dragRef.current?.pointerId) {
      endDragRef.current(false);
    }
  }, []);
  const onDragKey = useCallback((e: globalThis.KeyboardEvent) => {
    if (e.key === "Escape") {
      e.preventDefault();
      endDragRef.current(true);
    }
  }, []);

  const removeDragListeners = useCallback(() => {
    window.removeEventListener("pointermove", onDragMove);
    window.removeEventListener("pointerup", onDragUp);
    window.removeEventListener("pointercancel", onDragUp);
    window.removeEventListener("keydown", onDragKey);
  }, [onDragKey, onDragMove, onDragUp]);

  const endDrag = useCallback(
    (cancel: boolean) => {
      const drag = dragRef.current;
      if (!drag) {
        return;
      }
      removeDragListeners();
      const b = engine.body(drag.id);
      if (drag.mode === "pointer") {
        // Carry some of the throw into the settle spring.
        b.vx = b.pvx * 400;
        b.vy = b.pvy * 400;
      }
      b.pinned = false;
      b.liftTarget = 0;
      dragRef.current = null;
      if (cancel) {
        commit(drag.snapshot, drag.id);
      }
      engine.kick();
      setLiftedId(null);
      const title = titleOf(drag.id);
      if (cancel) {
        const index = drag.snapshot.findIndex((c) => c.id === drag.id);
        announce(
          `Move cancelled. ${title} returned to position ${index + 1} of ${drag.snapshot.length}.`
        );
      } else {
        announce(`${title} dropped at ${positionText(drag.id)}.`);
      }
    },
    [announce, commit, engine, positionText, removeDragListeners, titleOf]
  );
  endDragRef.current = endDrag;

  const liftPointer = useCallback(
    (id: string, pointerId: number, clientX: number, clientY: number) => {
      const rect = rectsRef.current.get(id);
      if (!rect || dragRef.current) {
        return;
      }
      const b = engine.body(id);
      const p = toGrid(clientX, clientY);
      dragRef.current = {
        id,
        mode: "pointer",
        pointerId,
        grabX: p.x - (rect.x + b.ox),
        grabY: p.y - (rect.y + b.oy),
        lastX: clientX,
        lastY: clientY,
        lastT: performance.now(),
        skipId: null,
        snapshot: layoutRef.current,
      };
      Object.assign(b, { pinned: true, hold: 0, vx: 0, vy: 0, pvx: 0, pvy: 0 });
      b.liftTarget = 1;
      engine.kick();
      setLiftedId(id);
      announce(`${titleOf(id)} lifted, ${positionText(id)}.`);
      navigator.vibrate?.(8);
      window.addEventListener("pointermove", onDragMove);
      window.addEventListener("pointerup", onDragUp);
      window.addEventListener("pointercancel", onDragUp);
      window.addEventListener("keydown", onDragKey);
    },
    [
      announce,
      engine,
      onDragKey,
      onDragMove,
      onDragUp,
      positionText,
      titleOf,
      toGrid,
    ]
  );

  /* ------------------------------ long press ------------------------------ */

  const onPressMove = useCallback((e: globalThis.PointerEvent) => {
    const press = pressRef.current;
    if (!press || e.pointerId !== press.pointerId) {
      return;
    }
    press.x = e.clientX;
    press.y = e.clientY;
    // Moving first means scrolling (touch) or selecting (mouse), not lifting.
    if (
      Math.hypot(e.clientX - press.startX, e.clientY - press.startY) >
      PRESS_SLOP
    ) {
      cancelPressRef.current();
    }
  }, []);

  const cancelPress = useCallback(() => {
    const press = pressRef.current;
    if (press) {
      window.clearTimeout(press.timer);
    }
    pressRef.current = null;
    window.removeEventListener("pointermove", onPressMove);
    window.removeEventListener("pointerup", cancelPressRef.current);
    window.removeEventListener("pointercancel", cancelPressRef.current);
  }, [onPressMove]);
  cancelPressRef.current = cancelPress;

  const startPress = useCallback(
    (e: ReactPointerEvent<HTMLDivElement>, id: string) => {
      const target = e.target as HTMLElement;
      if (
        dragRef.current ||
        resizeIdRef.current ||
        e.button !== 0 ||
        target.closest("[data-no-press]")
      ) {
        return;
      }
      cancelPress();
      pressRef.current = {
        id,
        pointerId: e.pointerId,
        startX: e.clientX,
        startY: e.clientY,
        x: e.clientX,
        y: e.clientY,
        timer: window.setTimeout(() => {
          const press = pressRef.current;
          cancelPressRef.current();
          if (press) {
            liftPointer(press.id, press.pointerId, press.x, press.y);
          }
        }, LONG_PRESS_MS),
      };
      window.addEventListener("pointermove", onPressMove);
      window.addEventListener("pointerup", cancelPress);
      window.addEventListener("pointercancel", cancelPress);
    },
    [cancelPress, liftPointer, onPressMove]
  );

  // A non-passive touchmove listener stops the page scrolling while a cell is
  // held. Until the long press fires, touch scrolling is left alone.
  useEffect(() => {
    const grid = gridRef.current;
    if (!grid) {
      return;
    }
    const block = (e: TouchEvent) => {
      if (dragRef.current?.mode === "pointer" || resizeIdRef.current) {
        e.preventDefault();
      }
    };
    grid.addEventListener("touchmove", block, { passive: false });
    return () => grid.removeEventListener("touchmove", block);
  }, []);

  /* -------------------------------- resize -------------------------------- */

  const spanText = useCallback((span: number) => {
    const isNarrow = narrowRef.current;
    const shown = isNarrow ? narrowSpan(span) : span;
    const cols = isNarrow ? NARROW_COLUMNS : COLUMNS;
    return `${shown} of ${cols} columns, ${SIZE_LABEL[sizeForSpan(span, isNarrow)]}`;
  }, []);

  const applySpan = useCallback(
    (id: string, span: number) => {
      const list = layoutRef.current;
      const entry = list.find((c) => c.id === id);
      if (!entry || entry.span === span) {
        return;
      }
      commit(
        list.map((c) => (c.id === id ? { ...c, span } : c)),
        id
      );
      announce(`${titleOf(id)} resized to ${spanText(span)}.`);
    },
    [announce, commit, spanText, titleOf]
  );

  /**
   * Whole-column span from how far the handle moved since the press. Using the
   * delta (not the cell's left edge) keeps it stable when the cell wraps rows.
   * Narrow grids only toggle between half and full width.
   */
  const spanFromPointer = useCallback((clientX: number) => {
    const start = resizeStartRef.current;
    const grid = gridRef.current;
    if (!(start && grid)) {
      return null;
    }
    const isNarrow = narrowRef.current;
    const cols = isNarrow ? NARROW_COLUMNS : COLUMNS;
    const colW = (grid.clientWidth + GAP) / cols;
    const steps = Math.round((clientX - start.x) / colW);
    if (!isNarrow) {
      return clampSpan(start.span + steps);
    }
    const n = Math.max(1, Math.min(2, narrowSpan(start.span) + steps));
    if (n === 1) {
      return MIN_SPAN;
    }
    return Math.max(3, start.span);
  }, []);

  const onResizeMove = useCallback(
    (e: globalThis.PointerEvent) => {
      const id = resizeIdRef.current;
      const span = spanFromPointer(e.clientX);
      if (id && span !== null) {
        applySpan(id, span);
      }
    },
    [applySpan, spanFromPointer]
  );

  const onResizeUp = useCallback(() => {
    resizeIdRef.current = null;
    setResizingId(null);
    window.removeEventListener("pointermove", onResizeMove);
    window.removeEventListener("pointerup", onResizeUp);
    window.removeEventListener("pointercancel", onResizeUp);
  }, [onResizeMove]);

  const startResize = useCallback(
    (e: ReactPointerEvent<HTMLButtonElement>, id: string) => {
      if (dragRef.current || e.button !== 0) {
        return;
      }
      e.preventDefault();
      cancelPress();
      resizeIdRef.current = id;
      resizeStartRef.current = {
        x: e.clientX,
        span: layoutRef.current.find((c) => c.id === id)?.span ?? MIN_SPAN,
      };
      setResizingId(id);
      window.addEventListener("pointermove", onResizeMove);
      window.addEventListener("pointerup", onResizeUp);
      window.addEventListener("pointercancel", onResizeUp);
    },
    [cancelPress, onResizeMove, onResizeUp]
  );

  const onResizeKeyDown = useCallback(
    (e: KeyboardEvent<HTMLButtonElement>, id: string) => {
      const entry = layoutRef.current.find((c) => c.id === id);
      let delta = 0;
      if (e.key === "ArrowRight" || e.key === "ArrowUp") {
        delta = 1;
      } else if (e.key === "ArrowLeft" || e.key === "ArrowDown") {
        delta = -1;
      }
      if (!entry || delta === 0) {
        return;
      }
      e.preventDefault();
      let span = clampSpan(entry.span + delta);
      if (narrowRef.current) {
        span = delta > 0 ? Math.max(3, entry.span) : MIN_SPAN;
      }
      applySpan(id, span);
    },
    [applySpan]
  );

  /* ------------------------------- keyboard ------------------------------- */

  /** Index of the closest cell in the row above or below. */
  const verticalNeighbor = useCallback((id: string, up: boolean) => {
    const list = layoutRef.current;
    const rects = rectsRef.current;
    const cur = rects.get(id);
    let best = -1;
    let bestDy = Number.POSITIVE_INFINITY;
    let bestDx = Number.POSITIVE_INFINITY;
    if (!cur) {
      return best;
    }
    const cx = cur.x + cur.w / 2;
    for (const [i, c] of list.entries()) {
      const r = rects.get(c.id);
      const inRow =
        r !== undefined &&
        (up ? r.y + r.h <= cur.y + 1 : r.y >= cur.y + cur.h - 1);
      if (r && inRow) {
        const dy = Math.abs(r.y - cur.y);
        const dx = Math.abs(r.x + r.w / 2 - cx);
        if (dy < bestDy - 1 || (Math.abs(dy - bestDy) <= 1 && dx < bestDx)) {
          best = i;
          bestDy = dy;
          bestDx = dx;
        }
      }
    }
    return best;
  }, []);

  const neighborIndex = useCallback(
    (id: string, key: string) => {
      const list = layoutRef.current;
      const index = list.findIndex((c) => c.id === id);
      if (key === "ArrowLeft") {
        return Math.max(0, index - 1);
      }
      if (key === "ArrowRight") {
        return Math.min(list.length - 1, index + 1);
      }
      if (key === "ArrowUp" || key === "ArrowDown") {
        const found = verticalNeighbor(id, key === "ArrowUp");
        return found < 0 ? index : found;
      }
      return null;
    },
    [verticalNeighbor]
  );

  const liftKeyboard = useCallback(
    (id: string) => {
      dragRef.current = {
        id,
        mode: "keyboard",
        pointerId: -1,
        grabX: 0,
        grabY: 0,
        lastX: 0,
        lastY: 0,
        lastT: 0,
        skipId: null,
        snapshot: layoutRef.current,
      };
      engine.body(id).liftTarget = 1;
      engine.kick();
      setLiftedId(id);
      announce(
        `${titleOf(id)} lifted, ${positionText(id)}. Arrow keys move it, Space drops it, Escape cancels.`
      );
    },
    [announce, engine, positionText, titleOf]
  );

  const moveByKey = useCallback(
    (id: string, key: string) => {
      const to = neighborIndex(id, key);
      if (to === null) {
        return false;
      }
      const list = layoutRef.current;
      const from = list.findIndex((c) => c.id === id);
      if (to === from) {
        announce(`${titleOf(id)} is at ${positionText(id)}.`);
        return true;
      }
      reorderingRef.current = true;
      commit(moveItem(list, from, to), id);
      announce(`${titleOf(id)} moved to position ${to + 1} of ${list.length}.`);
      return true;
    },
    [announce, commit, neighborIndex, positionText, titleOf]
  );

  const onGripKeyDown = useCallback(
    (e: KeyboardEvent<HTMLButtonElement>, id: string) => {
      const drag = dragRef.current;
      if (e.key === " " || e.key === "Enter") {
        e.preventDefault();
        if (drag?.id === id) {
          endDrag(false);
        } else if (!drag) {
          liftKeyboard(id);
        }
        return;
      }
      if (drag?.id !== id || drag.mode !== "keyboard") {
        return;
      }
      if (e.key === "Escape") {
        e.preventDefault();
        reorderingRef.current = true;
        endDrag(true);
        return;
      }
      if (moveByKey(id, e.key)) {
        e.preventDefault();
      }
    },
    [endDrag, liftKeyboard, moveByKey]
  );

  const onGripBlur = useCallback(
    (id: string) => {
      const drag = dragRef.current;
      if (
        drag?.mode === "keyboard" &&
        drag.id === id &&
        !reorderingRef.current
      ) {
        endDrag(false);
      }
    },
    [endDrag]
  );

  // Clean up timers, listeners and the loop on unmount.
  useEffect(
    () => () => {
      cancelPressRef.current();
      removeDragListeners();
      onResizeUp();
      engine.stop();
    },
    [engine, onResizeUp, removeDragListeners]
  );

  const activeId = liftedId ?? resizingId ?? pointedId;

  return (
    <div
      className={cn(
        "@container/wg w-full max-w-4xl [--wg-accent:var(--color-blue-600)] dark:[--wg-accent:var(--color-blue-400)]",
        className
      )}
      ref={wrapRef}
    >
      <div
        className="relative grid @xl/wg:grid-flow-row grid-flow-row-dense @xl/wg:grid-cols-6 grid-cols-2 [perspective:1400px]"
        ref={gridRef}
        style={{ gap: GAP, gridAutoRows: rowHeight }}
      >
        {current.map((entry) => {
          const item = itemsById.get(entry.id);
          if (!item) {
            return null;
          }
          const id = entry.id;
          return (
            <WidgetCell
              cellRef={(el) => {
                if (el) {
                  engine.els.set(id, el);
                } else {
                  engine.els.delete(id);
                }
              }}
              dimmed={activeId !== null && activeId !== id}
              gripRef={(el) => {
                if (el) {
                  gripsRef.current.set(id, el);
                } else {
                  gripsRef.current.delete(id);
                }
              }}
              instructionsId={instructionsId}
              item={item}
              key={id}
              lifted={liftedId === id}
              narrow={narrow}
              onFocusChange={(on) =>
                setPointedId((prev) => {
                  if (on) {
                    return id;
                  }
                  return prev === id ? null : prev;
                })
              }
              onGripBlur={() => onGripBlur(id)}
              onGripKeyDown={(e) => onGripKeyDown(e, id)}
              onGripPointerDown={(e) => {
                if (e.button === 0) {
                  e.preventDefault();
                  cancelPress();
                  liftPointer(id, e.pointerId, e.clientX, e.clientY);
                }
              }}
              onHover={(on) =>
                setPointedId((prev) => {
                  if (on) {
                    return id;
                  }
                  return prev === id ? null : prev;
                })
              }
              onPressStart={(e) => startPress(e, id)}
              onResizeKeyDown={(e) => onResizeKeyDown(e, id)}
              onResizePointerDown={(e) => startResize(e, id)}
              span={entry.span}
            />
          );
        })}
      </div>
      <p className="sr-only" id={instructionsId}>
        Press Space to pick up. Use the arrow keys to move, Space to drop and
        Escape to cancel. With a pointer, press and hold a widget, then drag it.
      </p>
      <p aria-live="assertive" className="sr-only">
        {message}
      </p>
    </div>
  );
}
```


---

# Flick Card
> A two-sided card you spin with a drag or a flick, with thickness, light and a floor shadow that follow the angle.

Source: https://kokonutui.com/docs/cards/card-flip

## Installation

```bash
npx shadcn@latest add @kokonutui/card-flip
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Flick Card
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  type Ref,
  useCallback,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// Degrees of turn per px of drag.
const DEG_PER_PX = 0.6;
// Spring that lands the card on a face, in degrees and seconds.
const STIFFNESS = 170;
const DAMPING = 20;
// How far ahead (in seconds of release velocity) the landing face is picked.
const PROJECTION = 0.22;
// A release faster than this (deg/s) always turns at least one face.
const FLICK_SPEED = 450;
// Never spin more than this many half turns from one flick.
const MAX_HALF_TURNS = 6;
// Movement below this (px) is a click, not a drag.
const DRAG_SLOP = 4;
// How far the card lifts toward the viewer at 90°, in px.
const LIFT = 36;
// Hover pre-tilt toward the pointer, in degrees.
const TILT = 6;
// Card thickness: stacked slices between the two faces.
const THICKNESS = 6;
const SLICES = 7;
const SLICE_DEPTHS = Array.from(
  { length: SLICES },
  (_, i) => -THICKNESS / 2 + (THICKNESS * (i + 0.5)) / SLICES
);
const SUBSTEP = 1 / 240;
// Release velocity is read from the last this-many ms of the drag.
const VELOCITY_WINDOW = 80;

const INTERACTIVE = "button, a, input, select, textarea, [data-no-flip]";

type Axis = "x" | "y";

export interface CardFlipProps {
  /** Front face. Defaults to an event ticket. */
  front?: ReactNode;
  /** Back face. Defaults to the ticket's entry code and seat. */
  back?: ReactNode;
  /** Controlled side: true shows the back. */
  flipped?: boolean;
  /** Starting side when uncontrolled. */
  defaultFlipped?: boolean;
  /** Called when a drag, click or key turns the card to the other side. */
  onFlippedChange?: (flipped: boolean) => void;
  /** "y" spins left and right like a coin, "x" tumbles top over bottom. */
  axis?: Axis;
  /** Accessible name of the card. */
  label?: string;
  className?: string;
  /** Classes for both faces, such as background, border and radius. */
  faceClassName?: string;
}

const mod2 = (n: number) => ((n % 2) + 2) % 2;
const sideOf = (angle: number) => mod2(Math.round(angle / 180)) === 1;
const nearestFace = (angle: number) => Math.round(angle / 180) * 180;

interface Sim {
  angle: number;
  velocity: number;
  target: number;
  raf: number;
  last: number;
  reduceMotion: boolean;
  pointerId: number | null;
  startX: number;
  startY: number;
  startAngle: number;
  dragging: boolean;
  samples: { t: number; a: number }[];
}

function cardTransform(axis: Axis, angle: number, lift: number) {
  const rotate = axis === "y" ? "rotateY" : "rotateX";
  return `translateZ(${lift.toFixed(2)}px) ${rotate}(${angle.toFixed(2)}deg)`;
}

// A flat band of light sweeps across whichever face is showing, and the face
// dims as it turns away from the light.
function paintLight(
  axis: Axis,
  sin: number,
  bands: (HTMLDivElement | null)[],
  shades: (HTMLDivElement | null)[]
) {
  const turn = Math.abs(sin);
  const shift = `${(sin * 140).toFixed(1)}%`;
  const transform =
    axis === "y"
      ? `translateX(${shift}) rotate(18deg)`
      : `translateY(${shift}) rotate(72deg)`;
  for (const band of bands) {
    if (band) {
      band.style.opacity = (turn * 0.12).toFixed(3);
      band.style.transform = transform;
    }
  }
  for (const shade of shades) {
    if (shade) {
      shade.style.opacity = (turn * 0.14).toFixed(3);
    }
  }
}

function releaseVelocity(samples: Sim["samples"], now: number) {
  const last = samples.at(-1);
  if (!last || now - last.t > VELOCITY_WINDOW) {
    return 0;
  }
  const first = samples.find((p) => last.t - p.t <= VELOCITY_WINDOW);
  if (!first || last.t <= first.t) {
    return 0;
  }
  return ((last.a - first.a) / (last.t - first.t)) * 1000;
}

export default function CardFlip({
  front,
  back,
  flipped,
  defaultFlipped = false,
  onFlippedChange,
  axis = "y",
  label = "Event ticket",
  className,
  faceClassName,
}: CardFlipProps) {
  const isControlled = flipped !== undefined;
  const [internalFlipped, setInternalFlipped] = useState(defaultFlipped);
  const isFlipped = isControlled ? flipped : internalFlipped;
  // Which face is turned toward the viewer right now (changes at 90°).
  const [backVisible, setBackVisible] = useState(isFlipped);
  // Bumped when a controlled card asks to turn; see the effect below.
  const [request, setRequest] = useState(0);
  const hintId = useId();

  const rootRef = useRef<HTMLDivElement>(null);
  const tiltRef = useRef<HTMLDivElement>(null);
  const cardRef = useRef<HTMLDivElement>(null);
  const shadowRef = useRef<HTMLDivElement>(null);
  const frontBandRef = useRef<HTMLDivElement>(null);
  const backBandRef = useRef<HTMLDivElement>(null);
  const frontShadeRef = useRef<HTMLDivElement>(null);
  const backShadeRef = useRef<HTMLDivElement>(null);

  // Styles React writes once; the spring owns them after that.
  const [initial] = useState(() => {
    const angle = isFlipped ? 180 : 0;
    return {
      angle,
      card: { transform: cardTransform(axis, angle, 0) },
      front: { transform: `translateZ(${THICKNESS / 2}px)` },
    };
  });

  const sim = useRef<Sim>({
    angle: initial.angle,
    velocity: 0,
    target: initial.angle,
    raf: 0,
    last: 0,
    reduceMotion: false,
    pointerId: null,
    startX: 0,
    startY: 0,
    startAngle: 0,
    dragging: false,
    samples: [],
  });

  // Latest props for the imperative handlers.
  const latest = useRef({ axis, isFlipped, isControlled, onFlippedChange });
  latest.current = { axis, isFlipped, isControlled, onFlippedChange };
  const backVisibleRef = useRef(backVisible);

  const render = useCallback(() => {
    const s = sim.current;
    const ax = latest.current.axis;
    const rad = (s.angle * Math.PI) / 180;
    const sin = Math.sin(rad);
    const turn = Math.abs(sin);
    const facing = Math.abs(Math.cos(rad));

    if (cardRef.current) {
      cardRef.current.style.transform = cardTransform(ax, s.angle, turn * LIFT);
    }
    if (shadowRef.current) {
      const narrow = (0.16 + 0.84 * facing).toFixed(3);
      const soft = (1 - turn * 0.12).toFixed(3);
      shadowRef.current.style.transform =
        ax === "y" ? `scale(${narrow}, ${soft})` : `scale(${soft}, ${narrow})`;
      shadowRef.current.style.opacity = (1 - turn * 0.45).toFixed(3);
    }
    paintLight(
      ax,
      sin,
      [frontBandRef.current, backBandRef.current],
      [frontShadeRef.current, backShadeRef.current]
    );

    const showsBack = sideOf(s.angle);
    if (showsBack !== backVisibleRef.current) {
      backVisibleRef.current = showsBack;
      setBackVisible(showsBack);
    }
  }, []);

  const step = useCallback(
    (now: number) => {
      const s = sim.current;
      const dt = Math.min(0.05, (now - s.last) / 1000);
      s.last = now;
      const n = Math.max(1, Math.ceil(dt / SUBSTEP));
      const h = dt / n;
      for (let i = 0; i < n; i++) {
        const force = -STIFFNESS * (s.angle - s.target) - DAMPING * s.velocity;
        s.velocity += force * h;
        s.angle += s.velocity * h;
      }
      if (Math.abs(s.angle - s.target) < 0.05 && Math.abs(s.velocity) < 0.5) {
        // Settled: park on 0 or 180 so the numbers never grow, then sleep.
        s.target = sideOf(s.target) ? 180 : 0;
        s.angle = s.target;
        s.velocity = 0;
        s.raf = 0;
        render();
        return;
      }
      render();
      s.raf = requestAnimationFrame(step);
    },
    [render]
  );

  const settle = useCallback(() => {
    const s = sim.current;
    if (s.reduceMotion) {
      // Reduced motion: no spin, land on the face at once.
      cancelAnimationFrame(s.raf);
      s.raf = 0;
      s.target = sideOf(s.target) ? 180 : 0;
      s.angle = s.target;
      s.velocity = 0;
      render();
      return;
    }
    if (!s.raf) {
      s.last = performance.now();
      s.raf = requestAnimationFrame(step);
    }
  }, [render, step]);

  // Point the spring at a face and report a side change.
  const aim = useCallback(
    (target: number) => {
      sim.current.target = target;
      const next = sideOf(target);
      const p = latest.current;
      if (next !== p.isFlipped) {
        if (p.isControlled) {
          setRequest((n) => n + 1);
        } else {
          setInternalFlipped(next);
        }
        p.onFlippedChange?.(next);
      }
      settle();
    },
    [settle]
  );

  const flipBy = useCallback(
    (direction: number) => {
      aim(nearestFace(sim.current.target) + 180 * direction);
    },
    [aim]
  );

  useEffect(() => {
    const s = sim.current;
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = query.matches;
    const onChange = () => {
      s.reduceMotion = query.matches;
    };
    query.addEventListener("change", onChange);
    return () => {
      query.removeEventListener("change", onChange);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, []);

  // Controlled: follow the prop when it disagrees with where the card lands.
  // `request` re-runs this after every turn the card asks for, so a parent
  // that ignores onFlippedChange sends the card back to its side.
  useEffect(() => {
    if (flipped === undefined || request < 0) {
      return;
    }
    const s = sim.current;
    if (s.dragging || sideOf(s.target) === flipped) {
      return;
    }
    // The nearest face on the asked-for side, so a refused turn swings back
    // the way it came.
    const face = nearestFace(s.angle);
    if (sideOf(face) === flipped) {
      s.target = face;
    } else {
      s.target = face + (s.angle < face ? -180 : 180);
    }
    settle();
  }, [flipped, request, settle]);

  // A new axis redraws the spring-owned transforms in place.
  useEffect(() => {
    latest.current.axis = axis;
    render();
  }, [axis, render]);

  const setTilt = (x: number, y: number) => {
    if (tiltRef.current) {
      tiltRef.current.style.transform = `rotateX(${(-y * TILT).toFixed(2)}deg) rotateY(${(x * TILT).toFixed(2)}deg)`;
    }
  };

  const onPointerDown = (e: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    // One pointer at a time: a second finger does not steal the drag.
    if (
      s.pointerId !== null ||
      e.button !== 0 ||
      (e.target as Element).closest(INTERACTIVE)
    ) {
      return;
    }
    s.pointerId = e.pointerId;
    s.startX = e.clientX;
    s.startY = e.clientY;
    s.startAngle = s.angle;
    s.dragging = false;
    s.samples = [{ t: e.timeStamp, a: s.angle }];
    e.currentTarget.setPointerCapture(e.pointerId);
  };

  const hoverTilt = (e: PointerEvent<HTMLDivElement>) => {
    if (e.pointerType !== "mouse" || !rootRef.current) {
      return;
    }
    const r = rootRef.current.getBoundingClientRect();
    setTilt(
      ((e.clientX - r.left) / r.width) * 2 - 1,
      ((e.clientY - r.top) / r.height) * 2 - 1
    );
  };

  const onPointerMove = (e: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    if (s.pointerId !== e.pointerId) {
      hoverTilt(e);
      return;
    }
    const dx = e.clientX - s.startX;
    const dy = e.clientY - s.startY;
    if (!s.dragging) {
      if (Math.hypot(dx, dy) < DRAG_SLOP) {
        return;
      }
      s.dragging = true;
      cancelAnimationFrame(s.raf);
      s.raf = 0;
      s.velocity = 0;
      setTilt(0, 0);
    }
    // One to one: the card stays under the finger.
    s.angle = s.startAngle + (axis === "y" ? dx : -dy) * DEG_PER_PX;
    s.samples.push({ t: e.timeStamp, a: s.angle });
    if (s.samples.length > 8) {
      s.samples.shift();
    }
    render();
  };

  const release = (e: PointerEvent<HTMLDivElement>, cancelled: boolean) => {
    const s = sim.current;
    if (s.pointerId !== e.pointerId) {
      return;
    }
    s.pointerId = null;
    if (!s.dragging) {
      if (!cancelled) {
        // A click pushes the half you pressed away from you.
        const r = e.currentTarget.getBoundingClientRect();
        const pushed =
          axis === "y"
            ? e.clientX > r.left + r.width / 2
            : e.clientY < r.top + r.height / 2;
        flipBy(pushed ? 1 : -1);
      }
      return;
    }
    s.dragging = false;

    const velocity = cancelled ? 0 : releaseVelocity(s.samples, e.timeStamp);
    const from = nearestFace(s.startAngle);
    let target = nearestFace(s.angle + velocity * PROJECTION);
    if (Math.abs(velocity) > FLICK_SPEED && target === from) {
      target = from + 180 * Math.sign(velocity);
    }
    const limit = MAX_HALF_TURNS * 180;
    target = Math.max(from - limit, Math.min(from + limit, target));
    s.velocity = velocity;
    aim(target);
  };

  const onKeyDown = (e: KeyboardEvent<HTMLDivElement>) => {
    if (e.target !== e.currentTarget) {
      return;
    }
    if (e.key === "Enter" || e.key === " ") {
      e.preventDefault();
      flipBy(1);
    }
  };

  const face = cn(
    "absolute inset-0 overflow-hidden rounded-2xl [backface-visibility:hidden]",
    "border border-zinc-200 bg-white text-zinc-900",
    "dark:border-zinc-800 dark:bg-zinc-900 dark:text-zinc-50",
    faceClassName
  );

  return (
    // biome-ignore lint/a11y/useSemanticElements: a labelled card whose faces hold their own content, not a plain button
    // biome-ignore lint/a11y/noNoninteractiveElementInteractions: drag, click and Enter or Space all turn the card
    <div
      aria-describedby={hintId}
      aria-label={label}
      aria-roledescription="flip card"
      className={cn(
        "group/flick relative aspect-[7/10] w-[260px] select-none rounded-2xl outline-hidden [perspective:1100px]",
        "focus-visible:ring-2 focus-visible:ring-orange-500 focus-visible:ring-offset-4 focus-visible:ring-offset-white dark:focus-visible:ring-offset-zinc-950",
        axis === "y" ? "touch-pan-y" : "touch-pan-x",
        className
      )}
      onKeyDown={onKeyDown}
      onLostPointerCapture={(e) => release(e, true)}
      onPointerCancel={(e) => release(e, true)}
      onPointerDown={onPointerDown}
      onPointerLeave={() => {
        if (sim.current.pointerId === null) {
          setTilt(0, 0);
        }
      }}
      onPointerMove={onPointerMove}
      onPointerUp={(e) => release(e, false)}
      ref={rootRef}
      role="group"
      // biome-ignore lint/a11y/noNoninteractiveTabindex: Enter and Space flip the card while it has focus
      tabIndex={0}
    >
      {/* Floor shadow: narrows and fades as the card turns edge-on. */}
      <div
        aria-hidden="true"
        className="pointer-events-none absolute inset-x-[8%] -bottom-7 h-6 rounded-[50%] bg-zinc-900/25 blur-md dark:bg-black/70"
        ref={shadowRef}
      />

      <div
        className="relative h-full w-full transition-transform duration-500 ease-[cubic-bezier(0.23,1,0.32,1)] [transform-style:preserve-3d] motion-reduce:transition-none"
        ref={tiltRef}
      >
        <div
          className="relative h-full w-full cursor-grab rounded-2xl [transform-style:preserve-3d] group-active/flick:cursor-grabbing"
          ref={cardRef}
          style={initial.card}
        >
          {/* The edge: thin slices stacked between the two faces. */}
          {SLICE_DEPTHS.map((z) => (
            <div
              aria-hidden="true"
              className="absolute inset-0 rounded-2xl bg-zinc-300 dark:bg-zinc-700"
              key={z}
              style={{ transform: `translateZ(${z.toFixed(3)}px)` }}
            />
          ))}

          <div
            aria-hidden={backVisible || undefined}
            className={face}
            inert={backVisible}
            style={initial.front}
          >
            {front ?? <TicketFront />}
            <LightBand bandRef={frontBandRef} shadeRef={frontShadeRef} />
          </div>

          <div
            aria-hidden={!backVisible || undefined}
            className={face}
            inert={!backVisible}
            style={{
              transform: `${axis === "y" ? "rotateY" : "rotateX"}(180deg) translateZ(${THICKNESS / 2}px)`,
            }}
          >
            {back ?? <TicketBack />}
            <LightBand bandRef={backBandRef} shadeRef={backShadeRef} />
          </div>
        </div>
      </div>

      <span className="sr-only" id={hintId}>
        Showing the {isFlipped ? "back" : "front"}. Press Enter or Space, or
        drag, to turn it over.
      </span>
    </div>
  );
}

function LightBand({
  bandRef,
  shadeRef,
}: {
  bandRef: Ref<HTMLDivElement>;
  shadeRef: Ref<HTMLDivElement>;
}) {
  return (
    <div
      aria-hidden="true"
      className="pointer-events-none absolute inset-0 flex items-center justify-center"
    >
      <div className="absolute inset-0 bg-black opacity-0" ref={shadeRef} />
      <div
        className="h-[220%] w-1/3 shrink-0 bg-white opacity-0"
        ref={bandRef}
      />
    </div>
  );
}

/* Demo faces: an event ticket. Pass your own front and back to replace them. */

const TICKET = {
  event: "Fieldwork Sessions",
  edition: "Vol. 04",
  date: "Sat 21 Nov",
  time: "19:30",
  venue: "Hall B, Pier 7",
  holder: "Jordan Vale",
  number: "004182",
  gate: "C",
  section: "Floor",
  row: "F",
  seat: "14",
};

function TicketFront() {
  return (
    <div className="flex h-full flex-col p-5">
      <div className="flex items-center justify-between">
        <span className="font-medium text-[11px] text-zinc-500 uppercase tracking-[0.14em] dark:text-zinc-400">
          Admit one
        </span>
        <span className="rounded-md bg-orange-500 px-1.5 py-0.5 font-medium text-[11px] text-white tracking-wide">
          GA
        </span>
      </div>

      <div className="mt-6">
        <p className="font-medium text-orange-600 text-xs tabular-nums dark:text-orange-400">
          {TICKET.edition}
        </p>
        <h3 className="mt-1 font-semibold text-[26px] leading-[1.05] tracking-tight">
          {TICKET.event}
        </h3>
      </div>

      <dl className="mt-auto grid grid-cols-2 gap-x-4 gap-y-3">
        <TicketField label="Date" value={TICKET.date} />
        <TicketField label="Doors" value={TICKET.time} />
        <TicketField label="Venue" value={TICKET.venue} wide />
      </dl>

      <div className="-mx-5 my-4 border-zinc-300 border-t border-dashed dark:border-zinc-700" />

      <div className="flex items-end justify-between">
        <div>
          <p className="text-[11px] text-zinc-500 dark:text-zinc-400">Holder</p>
          <p className="font-medium text-sm">{TICKET.holder}</p>
        </div>
        <p className="font-mono text-xs text-zinc-500 tabular-nums dark:text-zinc-400">
          No. {TICKET.number}
        </p>
      </div>
    </div>
  );
}

function TicketBack() {
  return (
    <div className="flex h-full flex-col p-5">
      <div className="flex items-center justify-between">
        <span className="font-medium text-[11px] text-zinc-500 uppercase tracking-[0.14em] dark:text-zinc-400">
          Scan at entry
        </span>
        <span className="font-mono text-xs text-zinc-500 tabular-nums dark:text-zinc-400">
          #{TICKET.number}
        </span>
      </div>

      <div className="mx-auto mt-4 w-[62%] rounded-xl bg-white p-2.5 ring-1 ring-zinc-200 dark:ring-0">
        <svg
          aria-label={`Entry code ${TICKET.number}`}
          className="block h-auto w-full"
          role="img"
          shapeRendering="crispEdges"
          viewBox={`0 0 ${QR_SIZE} ${QR_SIZE}`}
        >
          <path d={QR_PATH} fill="#18181b" />
        </svg>
      </div>

      <dl className="mt-auto grid grid-cols-4 gap-2 text-center">
        <TicketField label="Gate" value={TICKET.gate} />
        <TicketField label="Section" value={TICKET.section} />
        <TicketField label="Row" value={TICKET.row} />
        <TicketField label="Seat" value={TICKET.seat} />
      </dl>

      <p className="mt-4 border-zinc-200 border-t pt-3 text-[11px] text-zinc-500 leading-snug dark:border-zinc-800 dark:text-zinc-400">
        Valid for one entry. Re-entry with wristband only.
      </p>
    </div>
  );
}

function TicketField({
  label,
  value,
  wide,
}: {
  label: string;
  value: string;
  wide?: boolean;
}) {
  return (
    <div className={cn(wide && "col-span-2")}>
      <dt className="text-[11px] text-zinc-500 dark:text-zinc-400">{label}</dt>
      <dd className="font-medium text-sm">{value}</dd>
    </div>
  );
}

// A deterministic, QR-like code: three finder squares and seeded modules.
const QR_SIZE = 21;
const QR_PATH = buildQrPath(QR_SIZE, 4182);

function buildQrPath(size: number, seed: number) {
  let state = seed;
  const random = () => {
    state = (state * 16_807) % 2_147_483_647;
    return state / 2_147_483_647;
  };
  const far = size - 7;
  const inFinder = (x: number, y: number) =>
    (x < 8 && y < 8) || (x >= far - 1 && y < 8) || (x < 8 && y >= far - 1);
  const finderCell = (x: number, y: number) => {
    const fx = x >= far ? x - far : x;
    const fy = y >= far ? y - far : y;
    if (fx > 6 || fy > 6 || fx < 0 || fy < 0) {
      return false;
    }
    return Math.max(Math.abs(fx - 3), Math.abs(fy - 3)) !== 2;
  };
  let d = "";
  for (let y = 0; y < size; y++) {
    for (let x = 0; x < size; x++) {
      const on = inFinder(x, y) ? finderCell(x, y) : random() > 0.52;
      if (on) {
        d += `M${x} ${y}h1v1h-1z`;
      }
    }
  }
  return d;
}
```


---

# Throw Deck
> A pile of image cards you drag, flick off the top and send under the deck, with arrow keys and a details view.

Source: https://kokonutui.com/docs/cards/card-stack

## Installation

```bash
npx shadcn@latest add @kokonutui/card-stack
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Throw Deck
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { ChevronLeft, ChevronRight, X } from "lucide-react";
import {
  AnimatePresence,
  MotionConfig,
  motion,
  useReducedMotion,
} from "motion/react";
import {
  type CSSProperties,
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  type RefObject,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface DeckSpec {
  label: string;
  value: string;
}

export interface DeckCard {
  id: string;
  title: string;
  subtitle: string;
  /** Artwork shown edge to edge on the card. Inline SVG keeps it portable. */
  art: ReactNode;
  description: string;
  specs: DeckSpec[];
  price?: string;
}

export interface CardStackProps {
  cards?: DeckCard[];
  /** The one accent color, used by the artwork and the primary action. */
  accent?: string;
  /** Label of the primary action in the details view. */
  actionLabel?: string;
  onAction?: (card: DeckCard) => void;
  /** Called with the new top card after the deck cycles. */
  onChange?: (card: DeckCard) => void;
  className?: string;
}

// ---------------------------------------------------------------------------
// Physics
// ---------------------------------------------------------------------------

// Resting pose of each slot. The top card sits straight; the ones beneath
// keep a fixed tilt, like a pile squared up by hand.
const TILTS = [0, -2, 1.5, -1];
const SLOT_Y = 9;
const SLOT_SCALE = 0.035;
const MAX_SLOT = TILTS.length - 1;

// Dragging rotates the card up to this many degrees across its own width.
const MAX_DRAG_ROTATION = 18;
// A release throws the card when it is this fast (px/ms) or this far (share
// of the card's width). Anything less springs home.
const THROW_VELOCITY = 0.5;
const THROW_DISTANCE = 0.35;
// Taps that move less than this open the card instead of dragging it.
const TAP_SLOP = 5;
// Release velocity is measured over the last stretch of the gesture only.
const VELOCITY_WINDOW = 90;

// Springs as stiffness / damping (per second). Home is slightly underdamped
// so a hard release visibly carries through; the flight is looser so a faster
// flick travels further before it turns around.
const HOME = { k: 420, c: 30 };
const FLIGHT = { k: 150, c: 15 };
const RETURN = { k: 240, c: 26 };

const TOP_Z = 1000;

type Phase = "rest" | "drag" | "out" | "return";

interface Pose {
  x: number;
  y: number;
  r: number;
  s: number;
}

interface Body extends Pose {
  vx: number;
  vy: number;
  vr: number;
  vs: number;
  phase: Phase;
  /** Where a thrown card is headed before it turns around. */
  out: Pose;
  /** Unit direction of the throw. */
  dx: number;
  dy: number;
  /** Z-index override while in flight. */
  z: number | null;
  /** Z-index to take at the top of the arc. */
  apexZ: number | null;
}

interface Drag {
  pointerId: number;
  index: number;
  startX: number;
  startY: number;
  baseX: number;
  baseY: number;
  width: number;
  /** +1 when grabbed in the top half, −1 in the bottom half. */
  lever: number;
  moved: boolean;
  samples: { t: number; x: number; y: number }[];
}

function slotPose(depth: number): Pose {
  const d = Math.min(depth, MAX_SLOT);
  return { x: 0, y: d * SLOT_Y, r: TILTS[d] ?? 0, s: 1 - d * SLOT_SCALE };
}

function lerpPose(a: Pose, b: Pose, t: number): Pose {
  return {
    x: a.x + (b.x - a.x) * t,
    y: a.y + (b.y - a.y) * t,
    r: a.r + (b.r - a.r) * t,
    s: a.s + (b.s - a.s) * t,
  };
}

function poseTransform({ x, y, r, s }: Pose) {
  return `translate3d(${x.toFixed(2)}px, ${y.toFixed(2)}px, 0) rotate(${r.toFixed(3)}deg) scale(${s.toFixed(4)})`;
}

function makeBody(depth: number): Body {
  const pose = slotPose(depth);
  return {
    ...pose,
    vx: 0,
    vy: 0,
    vr: 0,
    vs: 0,
    phase: "rest",
    out: pose,
    dx: 1,
    dy: 0,
    z: null,
    apexZ: null,
  };
}

function springAxis(
  value: number,
  velocity: number,
  target: number,
  spring: { k: number; c: number },
  dt: number
) {
  const accel = -spring.k * (value - target) - spring.c * velocity;
  const v = velocity + accel * dt;
  return [value + v * dt, v] as const;
}

function stepBody(body: Body, target: Pose, dt: number) {
  let spring = HOME;
  if (body.phase === "out") {
    spring = FLIGHT;
  } else if (body.phase === "return") {
    spring = RETURN;
  }
  // Sub-step so a stiff spring stays stable on a slow frame.
  const steps = Math.max(1, Math.ceil(dt * 240));
  const h = dt / steps;
  for (let i = 0; i < steps; i++) {
    [body.x, body.vx] = springAxis(body.x, body.vx, target.x, spring, h);
    [body.y, body.vy] = springAxis(body.y, body.vy, target.y, spring, h);
    [body.r, body.vr] = springAxis(body.r, body.vr, target.r, spring, h);
    [body.s, body.vs] = springAxis(body.s, body.vs, target.s, spring, h);
  }
}

function isSettled(body: Body, target: Pose) {
  return (
    Math.abs(body.x - target.x) < 0.1 &&
    Math.abs(body.y - target.y) < 0.1 &&
    Math.abs(body.r - target.r) < 0.02 &&
    Math.abs(body.s - target.s) < 0.0005 &&
    Math.abs(body.vx) + Math.abs(body.vy) < 2 &&
    Math.abs(body.vr) < 1 &&
    Math.abs(body.vs) < 0.01
  );
}

/** Distance along (ux, uy) at which a w×h card no longer covers the deck. */
function clearance(w: number, h: number, ux: number, uy: number) {
  const along = Math.min(
    ux === 0 ? Number.POSITIVE_INFINITY : w / Math.abs(ux),
    uy === 0 ? Number.POSITIVE_INFINITY : h / Math.abs(uy)
  );
  return along + 24;
}

function releaseVelocity(samples: Drag["samples"]) {
  const last = samples.at(-1);
  const first = samples.find(
    (sample) => last && last.t - sample.t <= VELOCITY_WINDOW
  );
  if (!(first && last) || last.t - first.t < 8) {
    return { vx: 0, vy: 0 };
  }
  const dt = last.t - first.t;
  return { vx: (last.x - first.x) / dt, vy: (last.y - first.y) / dt };
}

function cardState(phase: Phase) {
  if (phase === "drag") {
    return "drag";
  }
  return phase === "rest" ? "rest" : "fly";
}

// ---------------------------------------------------------------------------
// Component
// ---------------------------------------------------------------------------

export default function CardStack({
  cards = DEFAULT_CARDS,
  accent = "#f97316",
  actionLabel = "Add to cart",
  onAction,
  onChange,
  className,
}: CardStackProps) {
  const count = cards.length;
  const [order, setOrder] = useState(() => cards.map((_, i) => i));
  const [openId, setOpenId] = useState<string | null>(null);
  const reduceMotion = useReducedMotion();

  const orderRef = useRef(order);
  const bodies = useRef<Body[]>(cards.map((_, i) => makeBody(i)));
  const nodes = useRef<(HTMLButtonElement | null)[]>([]);
  const drag = useRef<Drag | null>(null);
  // 0–1: how close the current drag is to a throw. The card beneath rises
  // to meet it.
  const progress = useRef(0);
  const raf = useRef(0);
  const last = useRef(0);
  const reduced = useRef(false);
  const suppressClick = useRef(false);
  const focusTop = useRef(false);
  const closeRef = useRef<HTMLButtonElement>(null);
  const onChangeRef = useRef(onChange);
  onChangeRef.current = onChange;
  reduced.current = reduceMotion === true;

  const write = useCallback((index: number, depth: number) => {
    const node = nodes.current[index];
    const body = bodies.current[index];
    if (!(node && body)) {
      return;
    }
    node.style.transform = poseTransform(body);
    node.style.zIndex = String(body.z ?? orderRef.current.length - depth);
    const state = cardState(body.phase);
    if (node.dataset.state !== state) {
      node.dataset.state = state;
    }
  }, []);

  const targetFor = useCallback((body: Body, depth: number): Pose => {
    if (body.phase === "out") {
      return body.out;
    }
    const pose = slotPose(depth);
    if (depth > 0 && progress.current > 0) {
      return lerpPose(pose, slotPose(depth - 1), progress.current * 0.6);
    }
    return pose;
  }, []);

  const advance = useCallback(
    (index: number, depth: number, dt: number) => {
      const body = bodies.current[index];
      if (!body) {
        return false;
      }
      if (body.phase === "drag") {
        write(index, depth);
        return true;
      }
      if (reduced.current && body.phase === "out") {
        body.phase = "rest";
        body.z = null;
      }
      const target = targetFor(body, depth);
      if (reduced.current) {
        Object.assign(body, target, { vx: 0, vy: 0, vr: 0, vs: 0 });
      } else {
        stepBody(body, target, dt);
      }
      // Top of the arc: the card stops travelling outward, swaps to its new
      // layer while it is clear of the deck, and heads home.
      if (body.phase === "out" && body.vx * body.dx + body.vy * body.dy <= 0) {
        body.phase = "return";
        body.z = body.apexZ;
      }
      const settled = isSettled(body, target);
      if (settled && body.phase !== "out") {
        body.phase = "rest";
        body.z = null;
      }
      write(index, depth);
      return !settled;
    },
    [targetFor, write]
  );

  const tick = useCallback(
    (now: number) => {
      const dt = Math.min((now - last.current) / 1000, 1 / 30);
      last.current = now;
      let active = false;
      orderRef.current.forEach((index, depth) => {
        if (advance(index, depth, dt)) {
          active = true;
        }
      });
      raf.current = active ? requestAnimationFrame(tick) : 0;
    },
    [advance]
  );

  // The loop sleeps whenever every card has settled; anything that moves a
  // card wakes it.
  const kick = useCallback(() => {
    if (raf.current) {
      return;
    }
    last.current = performance.now();
    raf.current = requestAnimationFrame(tick);
  }, [tick]);

  useEffect(() => () => cancelAnimationFrame(raf.current), []);

  const commitOrder = useCallback(
    (next: number[]) => {
      orderRef.current = next;
      setOrder(next);
      const top = cards[next[0] ?? 0];
      if (top) {
        onChangeRef.current?.(top);
      }
      kick();
    },
    [cards, kick]
  );

  // Send the top card flying along (vx, vy) px/ms; it comes back under the
  // pile. (fx, fy) is the direction to use when there is no real velocity.
  const throwTop = useCallback(
    (vx: number, vy: number, fx: number, fy: number) => {
      const current = orderRef.current;
      const index = current[0];
      if (index === undefined || current.length < 2) {
        return;
      }
      const body = bodies.current[index];
      const node = nodes.current[index];
      if (!body) {
        return;
      }
      const speed = Math.hypot(vx, vy);
      const rawX = speed > 0.05 ? vx : fx;
      const rawY = speed > 0.05 ? vy : fy;
      const norm = Math.hypot(rawX, rawY) || 1;
      const ux = rawX / norm;
      const uy = rawY / norm;
      const w = node?.offsetWidth ?? 256;
      const h = node?.offsetHeight ?? 320;
      const distance = clearance(w, h, ux, uy) + Math.min(speed * 50, 90);
      // Keep some speed so a slow but far drag still leaves with intent.
      const launch = Math.max(speed, 0.9) * 1000;
      body.phase = "out";
      body.dx = ux;
      body.dy = uy;
      body.out = {
        x: ux * distance,
        y: uy * distance,
        r: Math.max(-40, Math.min(40, body.r + ux * 26)),
        s: 1,
      };
      body.vx = ux * launch;
      body.vy = uy * launch;
      body.vr += ux * launch * 0.05;
      body.z = TOP_Z;
      body.apexZ = null;
      commitOrder([...current.slice(1), index]);
    },
    [commitOrder]
  );

  // The bottom card slips out to the left, swaps on top at its apex and lands
  // as the new top card.
  const bringBack = useCallback(() => {
    const current = orderRef.current;
    const index = current.at(-1);
    if (index === undefined || current.length < 2) {
      return;
    }
    const body = bodies.current[index];
    const node = nodes.current[index];
    if (!body) {
      return;
    }
    const ux = -0.97;
    const uy = -0.24;
    const w = node?.offsetWidth ?? 256;
    const h = node?.offsetHeight ?? 320;
    const distance = clearance(w, h, ux, uy) + 20;
    body.phase = "out";
    body.dx = ux;
    body.dy = uy;
    body.out = { x: ux * distance, y: uy * distance, r: -16, s: 1 };
    body.vx = ux * 1100;
    body.vy = uy * 1100;
    body.z = 0;
    body.apexZ = TOP_Z - 1;
    commitOrder([index, ...current.slice(0, -1)]);
  }, [commitOrder]);

  const cycle = useCallback(
    (direction: 1 | -1) => {
      if (direction === 1) {
        throwTop(1.3, -0.35, 1, 0);
      } else {
        bringBack();
      }
    },
    [throwTop, bringBack]
  );

  // Keep keyboard focus on whichever card is now on top.
  useEffect(() => {
    if (!focusTop.current || openId) {
      return;
    }
    focusTop.current = false;
    const topCard = order[0];
    if (topCard !== undefined) {
      nodes.current[topCard]?.focus({ preventScroll: true });
    }
  }, [order, openId]);

  const closeDetails = useCallback(() => {
    focusTop.current = true;
    setOpenId(null);
  }, []);

  useEffect(() => {
    if (!openId) {
      return;
    }
    closeRef.current?.focus({ preventScroll: true });
    const onKey = (event: globalThis.KeyboardEvent) => {
      if (event.key === "Escape") {
        event.preventDefault();
        closeDetails();
      }
    };
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [openId, closeDetails]);

  const handlePointerDown = (
    event: PointerEvent<HTMLButtonElement>,
    index: number
  ) => {
    suppressClick.current = false;
    if (drag.current || orderRef.current[0] !== index) {
      return;
    }
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    const body = bodies.current[index];
    if (!body) {
      return;
    }
    const node = event.currentTarget;
    const rect = node.getBoundingClientRect();
    node.setPointerCapture(event.pointerId);
    drag.current = {
      pointerId: event.pointerId,
      index,
      startX: event.clientX,
      startY: event.clientY,
      baseX: body.x,
      baseY: body.y,
      width: node.offsetWidth,
      lever: event.clientY - rect.top < rect.height / 2 ? 1 : -1,
      moved: false,
      samples: [{ t: event.timeStamp, x: event.clientX, y: event.clientY }],
    };
  };

  const handlePointerMove = (event: PointerEvent<HTMLButtonElement>) => {
    const current = drag.current;
    if (!current || current.pointerId !== event.pointerId) {
      return;
    }
    const dx = event.clientX - current.startX;
    const dy = event.clientY - current.startY;
    if (!current.moved) {
      if (Math.hypot(dx, dy) < TAP_SLOP) {
        return;
      }
      // Axis lock for touch: a mostly vertical swipe is a page scroll, so
      // let go of the card and leave it to the browser (touch-pan-y).
      if (event.pointerType !== "mouse" && Math.abs(dy) > Math.abs(dx)) {
        drag.current = null;
        if (event.currentTarget.hasPointerCapture(event.pointerId)) {
          event.currentTarget.releasePointerCapture(event.pointerId);
        }
        return;
      }
    }
    const body = bodies.current[current.index];
    if (!body) {
      return;
    }
    current.moved = true;
    current.samples.push({
      t: event.timeStamp,
      x: event.clientX,
      y: event.clientY,
    });
    if (current.samples.length > 24) {
      current.samples.shift();
    }
    body.phase = "drag";
    body.x = current.baseX + dx;
    body.y = current.baseY + dy;
    body.s = 1;
    // Pivot at the bottom edge: grabbing the top half swings the top out,
    // grabbing the bottom half swings it the other way.
    body.r =
      Math.max(-1, Math.min(1, body.x / current.width)) *
      MAX_DRAG_ROTATION *
      current.lever;
    body.vx = 0;
    body.vy = 0;
    body.vr = 0;
    body.vs = 0;
    progress.current = Math.min(
      Math.hypot(body.x, body.y) / (current.width * THROW_DISTANCE),
      1
    );
    kick();
  };

  const handlePointerUp = (
    event: PointerEvent<HTMLButtonElement>,
    cancelled = false
  ) => {
    const current = drag.current;
    if (!current || current.pointerId !== event.pointerId) {
      return;
    }
    drag.current = null;
    progress.current = 0;
    const body = bodies.current[current.index];
    if (!(body && current.moved)) {
      kick();
      return;
    }
    if (cancelled) {
      // The browser took the gesture (or capture was lost): no throw, no
      // click, just spring home.
      body.phase = "rest";
      kick();
      return;
    }
    suppressClick.current = true;
    const { vx, vy } = releaseVelocity(current.samples);
    const speed = Math.hypot(vx, vy);
    const distance = Math.hypot(body.x, body.y);
    // A flick back toward the deck is a change of mind, not a throw.
    const heading = distance > 0 ? (vx * body.x + vy * body.y) / distance : 0;
    const fast = speed > THROW_VELOCITY && heading > -0.2;
    const far = distance > current.width * THROW_DISTANCE && heading > -0.3;
    if (fast || far) {
      throwTop(vx, vy, body.x / (distance || 1), body.y / (distance || 1));
      return;
    }
    // Spring home, carrying the release velocity into the spring.
    body.phase = "rest";
    body.vx = vx * 1000;
    body.vy = vy * 1000;
    body.vr = ((vx * 1000) / current.width) * MAX_DRAG_ROTATION * current.lever;
    kick();
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLButtonElement>) => {
    // A drag that ended without its click must not swallow Enter or Space.
    suppressClick.current = false;
    if (event.key === "ArrowRight" || event.key === "ArrowDown") {
      event.preventDefault();
      focusTop.current = true;
      cycle(1);
    } else if (event.key === "ArrowLeft" || event.key === "ArrowUp") {
      event.preventDefault();
      focusTop.current = true;
      cycle(-1);
    }
  };

  const topIndex = order[0] ?? 0;
  const top = cards[topIndex];
  const open = openId ? cards.find((card) => card.id === openId) : undefined;

  return (
    <MotionConfig reducedMotion="user">
      <div
        className={cn(
          "relative mx-auto flex min-h-[32rem] w-full max-w-md flex-col items-center justify-center py-8",
          className
        )}
        style={{ "--deck-accent": accent } as CSSProperties}
      >
        <section
          aria-label="Card deck. Drag a card away or use the arrow keys to cycle."
          className="relative aspect-[4/5] w-[min(16rem,calc(100%-5rem))]"
        >
          {cards.map((card, index) => {
            const depth = order.indexOf(index);
            const isTop = depth === 0;
            const isOpen = openId === card.id;
            return (
              <button
                aria-label={`${card.title}, ${card.subtitle}. Open details`}
                className={cn(
                  "group/deck-card absolute inset-0 origin-bottom touch-pan-y select-none rounded-2xl text-left outline-none will-change-transform",
                  "shadow-[0_1px_2px_rgb(0_0_0/0.05),0_4px_12px_-4px_rgb(0_0_0/0.12)] transition-shadow duration-200 ease-out dark:shadow-[0_1px_2px_rgb(0_0_0/0.4),0_6px_16px_-6px_rgb(0_0_0/0.7)]",
                  "data-[state=drag]:shadow-[0_2px_4px_rgb(0_0_0/0.05),0_28px_48px_-16px_rgb(0_0_0/0.3)] data-[state=fly]:shadow-[0_2px_4px_rgb(0_0_0/0.05),0_28px_48px_-16px_rgb(0_0_0/0.3)]",
                  "focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-4 focus-visible:ring-offset-white dark:focus-visible:ring-offset-zinc-950",
                  isTop && "cursor-grab data-[state=drag]:cursor-grabbing",
                  isOpen && "shadow-none dark:shadow-none"
                )}
                data-state="rest"
                inert={!isTop}
                key={card.id}
                onClick={() => {
                  if (suppressClick.current) {
                    suppressClick.current = false;
                    return;
                  }
                  if (orderRef.current[0] === index) {
                    setOpenId(card.id);
                  }
                }}
                onKeyDown={handleKeyDown}
                onLostPointerCapture={(event) => handlePointerUp(event, true)}
                onPointerCancel={(event) => handlePointerUp(event, true)}
                onPointerDown={(event) => handlePointerDown(event, index)}
                onPointerMove={handlePointerMove}
                onPointerUp={(event) => handlePointerUp(event)}
                ref={(node) => {
                  nodes.current[index] = node;
                }}
                style={{
                  transform: poseTransform(slotPose(index)),
                  zIndex: count - index,
                }}
                tabIndex={isTop ? 0 : -1}
                type="button"
              >
                {!isOpen && (
                  <motion.span
                    className="flex h-full flex-col rounded-2xl border border-zinc-200 bg-white p-2 dark:border-zinc-800 dark:bg-zinc-900"
                    layoutDependency={openId}
                    layoutId={`deck-${card.id}`}
                    transition={LAYOUT_SPRING}
                  >
                    <motion.span
                      className="relative block min-h-0 flex-1 overflow-hidden rounded-xl"
                      layoutDependency={openId}
                      layoutId={`deck-art-${card.id}`}
                      transition={LAYOUT_SPRING}
                    >
                      {card.art}
                    </motion.span>
                    <span className="flex items-end justify-between gap-3 px-1.5 pt-2.5 pb-1">
                      <span className="min-w-0">
                        <span className="block truncate font-medium text-sm text-zinc-900 dark:text-zinc-100">
                          {card.title}
                        </span>
                        <span className="block truncate text-xs text-zinc-500 dark:text-zinc-400">
                          {card.subtitle}
                        </span>
                      </span>
                      {card.price && (
                        <span className="shrink-0 text-sm text-zinc-900 tabular-nums dark:text-zinc-100">
                          {card.price}
                        </span>
                      )}
                    </span>
                  </motion.span>
                )}
              </button>
            );
          })}
        </section>

        <div className="mt-8 flex w-[min(16rem,calc(100%-5rem))] items-center justify-between gap-2">
          <button
            aria-label="Previous card"
            className={NAV_BUTTON}
            onClick={() => cycle(-1)}
            type="button"
          >
            <ChevronLeft className="size-4" />
          </button>
          <p
            aria-live="polite"
            className="min-w-0 truncate text-center text-xs text-zinc-500 tabular-nums dark:text-zinc-400"
          >
            <span className="text-zinc-900 dark:text-zinc-100">
              {String(topIndex + 1).padStart(2, "0")}
            </span>
            {" / "}
            {String(count).padStart(2, "0")}
            <span className="sr-only">: {top?.title}</span>
          </p>
          <button
            aria-label="Next card"
            className={NAV_BUTTON}
            onClick={() => cycle(1)}
            type="button"
          >
            <ChevronRight className="size-4" />
          </button>
        </div>

        <AnimatePresence>
          {open && (
            <DeckDetails
              actionLabel={actionLabel}
              card={open}
              closeRef={closeRef}
              key="details"
              onAction={onAction}
              onClose={closeDetails}
              openId={openId}
            />
          )}
        </AnimatePresence>
      </div>
    </MotionConfig>
  );
}

function DeckDetails({
  card,
  openId,
  actionLabel,
  onAction,
  onClose,
  closeRef,
}: {
  card: DeckCard;
  openId: string | null;
  actionLabel: string;
  onAction?: (card: DeckCard) => void;
  onClose: () => void;
  closeRef: RefObject<HTMLButtonElement | null>;
}) {
  return (
    <motion.div
      animate={{ opacity: 1 }}
      className="absolute inset-0 z-[2000] flex items-center justify-center bg-white/85 p-3 dark:bg-zinc-950/85"
      exit={{ opacity: 0 }}
      initial={{ opacity: 0 }}
      onClick={(event) => {
        if (event.target === event.currentTarget) {
          onClose();
        }
      }}
      transition={{ duration: 0.2, ease: EASE_OUT }}
    >
      <motion.div
        aria-label={card.title}
        aria-modal="true"
        className="relative flex max-h-full w-full max-w-sm flex-col overflow-hidden rounded-2xl border border-zinc-200 bg-white p-2 shadow-[0_24px_48px_-12px_rgb(0_0_0/0.25)] dark:border-zinc-800 dark:bg-zinc-900"
        layoutDependency={openId}
        layoutId={`deck-${card.id}`}
        role="dialog"
        transition={LAYOUT_SPRING}
      >
        <motion.div
          className="relative aspect-[2/1] w-full shrink-0 overflow-hidden rounded-xl"
          layoutDependency={openId}
          layoutId={`deck-art-${card.id}`}
          transition={LAYOUT_SPRING}
        >
          {card.art}
        </motion.div>
        <motion.div
          animate={{ opacity: 1, y: 0 }}
          className="min-h-0 overflow-y-auto px-2 pt-3 pb-1"
          exit={{ opacity: 0, transition: { duration: 0.1 } }}
          initial={{ opacity: 0, y: 6 }}
          transition={{ duration: 0.25, delay: 0.08, ease: EASE_OUT }}
        >
          <div className="flex items-baseline justify-between gap-3">
            <h3 className="font-medium text-base text-zinc-900 dark:text-zinc-100">
              {card.title}
            </h3>
            {card.price && (
              <span className="text-sm text-zinc-900 tabular-nums dark:text-zinc-100">
                {card.price}
              </span>
            )}
          </div>
          <p className="text-xs text-zinc-500 dark:text-zinc-400">
            {card.subtitle}
          </p>
          <p className="mt-2 text-sm text-zinc-600 leading-relaxed dark:text-zinc-300">
            {card.description}
          </p>
          <dl className="mt-3 grid grid-cols-3 gap-px overflow-hidden rounded-lg border border-zinc-200 bg-zinc-200 dark:border-zinc-800 dark:bg-zinc-800">
            {card.specs.map((spec) => (
              <div
                className="min-w-0 bg-white px-2.5 py-2 dark:bg-zinc-900"
                key={spec.label}
              >
                <dt className="text-[11px] text-zinc-500 dark:text-zinc-400">
                  {spec.label}
                </dt>
                <dd className="truncate text-xs text-zinc-900 dark:text-zinc-100">
                  {spec.value}
                </dd>
              </div>
            ))}
          </dl>
          <button
            className="mt-3 h-9 w-full rounded-lg bg-[var(--deck-accent)] font-medium text-sm text-white transition-[filter] duration-150 ease-out hover:brightness-110 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 active:brightness-95 dark:focus-visible:ring-offset-zinc-900"
            onClick={() => onAction?.(card)}
            type="button"
          >
            {actionLabel}
          </button>
        </motion.div>
        <button
          aria-label="Close details"
          className="absolute top-4 right-4 flex size-7 items-center justify-center rounded-full bg-white text-zinc-600 transition-colors duration-150 hover:text-zinc-900 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 dark:bg-zinc-900 dark:text-zinc-300 dark:hover:text-zinc-100"
          onClick={onClose}
          ref={closeRef}
          type="button"
        >
          <X className="size-3.5" />
        </button>
      </motion.div>
    </motion.div>
  );
}

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const LAYOUT_SPRING = { type: "spring", duration: 0.45, bounce: 0 } as const;
const NAV_BUTTON =
  "flex size-8 shrink-0 items-center justify-center rounded-full border border-zinc-200 text-zinc-600 transition-colors duration-150 hover:bg-zinc-100 hover:text-zinc-900 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 active:translate-y-px dark:border-zinc-800 dark:text-zinc-400 dark:hover:bg-zinc-800 dark:hover:text-zinc-100";

// ---------------------------------------------------------------------------
// Demo artwork: flat zinc compositions with one accent, drawn inline so the
// component ships with no image files.
// ---------------------------------------------------------------------------

const BG = "fill-zinc-100 dark:fill-zinc-800";
const MID = "fill-zinc-300 dark:fill-zinc-700";
const INK = "fill-zinc-800 dark:fill-zinc-300";
const ACCENT = { fill: "var(--deck-accent)" };

function Art({ children, dark }: { children: ReactNode; dark?: boolean }) {
  return (
    <svg
      aria-hidden="true"
      className="absolute inset-0 size-full"
      preserveAspectRatio="xMidYMid slice"
      viewBox="0 0 320 320"
    >
      <rect
        className={dark ? "fill-zinc-900 dark:fill-zinc-950" : BG}
        height="320"
        width="320"
      />
      {children}
    </svg>
  );
}

const STRIPES = [0, 1, 2, 3, 4, 5, 6];

function LowSunArt() {
  return (
    <Art>
      <circle cx="160" cy="176" r="72" style={ACCENT} />
      <rect className={MID} height="144" width="320" y="176" />
      {STRIPES.map((i) => (
        <rect
          height={4 - i * 0.4}
          key={i}
          style={ACCENT}
          width={120 - i * 14}
          x={100 + i * 7}
          y={190 + i * 14}
        />
      ))}
    </Art>
  );
}

function RidgeArt() {
  return (
    <Art>
      <circle cx="232" cy="108" r="22" style={ACCENT} />
      <polygon
        className={MID}
        points="0,200 64,132 112,172 176,96 248,164 320,120 320,320 0,320"
      />
      <polygon
        className={INK}
        points="0,240 88,176 148,220 224,160 320,236 320,320 0,320"
      />
    </Art>
  );
}

const RINGS = [24, 48, 72, 96, 120, 144, 168, 192];

function TideArt() {
  return (
    <Art>
      {RINGS.map((r) => (
        <circle
          className="fill-none stroke-zinc-300 dark:stroke-zinc-700"
          cx="132"
          cy="188"
          key={r}
          r={r}
          strokeWidth="2"
        />
      ))}
      <circle cx="132" cy="188" r="14" style={ACCENT} />
      <circle className={INK} cx="244" cy="104" r="6" />
    </Art>
  );
}

const WINDOWS = Array.from({ length: 30 }, (_, i) => i);
const LIT = new Set([7, 16, 23]);

function NightArt() {
  return (
    <Art dark>
      {WINDOWS.map((i) => (
        <rect
          className={
            LIT.has(i) ? undefined : "fill-zinc-700 dark:fill-zinc-800"
          }
          height="30"
          key={i}
          rx="2"
          style={LIT.has(i) ? ACCENT : undefined}
          width="30"
          x={52 + (i % 5) * 46}
          y={52 + Math.floor(i / 5) * 40}
        />
      ))}
    </Art>
  );
}

function SaltArt() {
  return (
    <Art>
      <circle cx="96" cy="108" r="14" style={ACCENT} />
      <rect
        className="fill-zinc-200 dark:fill-zinc-700"
        height="148"
        width="320"
        y="172"
      />
      <polygon
        className="fill-zinc-300 dark:fill-zinc-600"
        points="214,172 40,196 40,200 218,173"
      />
      <rect className={INK} height="56" width="4" x="212" y="116" />
    </Art>
  );
}

const DEFAULT_CARDS: DeckCard[] = [
  {
    id: "low-sun",
    title: "Low Sun",
    subtitle: "Print 01 · Risograph",
    art: <LowSunArt />,
    description:
      "The last ten minutes of light over open water, pulled in two passes on warm cream stock.",
    specs: [
      { label: "Size", value: "A3" },
      { label: "Paper", value: "Cream 120g" },
      { label: "Edition", value: "of 50" },
    ],
    price: "$48",
  },
  {
    id: "ridge-line",
    title: "Ridge Line",
    subtitle: "Print 02 · Screen print",
    art: <RidgeArt />,
    description:
      "Two ranges, one sun. Hand-pulled in three layers, with a slight misregister on purpose.",
    specs: [
      { label: "Size", value: "50 × 70" },
      { label: "Paper", value: "Natural 300g" },
      { label: "Edition", value: "of 30" },
    ],
    price: "$72",
  },
  {
    id: "tide-pools",
    title: "Tide Pools",
    subtitle: "Print 03 · Risograph",
    art: <TideArt />,
    description:
      "Rings left by a single stone, printed as eight hairlines around one accent dot.",
    specs: [
      { label: "Size", value: "A3" },
      { label: "Paper", value: "White 120g" },
      { label: "Edition", value: "of 80" },
    ],
    price: "$40",
  },
  {
    id: "night-market",
    title: "Night Market",
    subtitle: "Print 04 · Giclée",
    art: <NightArt />,
    description:
      "A block of windows after closing time. Three are still lit; the rest have gone home.",
    specs: [
      { label: "Size", value: "40 × 50" },
      { label: "Paper", value: "Cotton 310g" },
      { label: "Edition", value: "Open" },
    ],
    price: "$56",
  },
  {
    id: "salt-flats",
    title: "Salt Flats",
    subtitle: "Print 05 · Screen print",
    art: <SaltArt />,
    description:
      "One marker post and its shadow across a dry lake bed. Mostly empty, which is the point.",
    specs: [
      { label: "Size", value: "50 × 70" },
      { label: "Paper", value: "Bright 300g" },
      { label: "Edition", value: "of 25" },
    ],
    price: "$64",
  },
];
```


---

# Momentum Rail
> A card rail you flick with momentum, snapping on a spring, with scroll-driven cover-flow depth and parallax.

Source: https://kokonutui.com/docs/cards/carousel-cards

## Installation

```bash
npx shadcn@latest add @kokonutui/carousel-cards
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Momentum Rail. A card rail you can flick with the mouse: the
 * release velocity projects an end point, a spring snaps to the nearest card
 * and the ends rubber-band. Scroll position drives a cover-flow depth, image
 * parallax and the centered card's details with CSS scroll-driven animations.
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { ChevronLeft, ChevronRight, Star } from "lucide-react";
import {
  type CSSProperties,
  type ReactNode,
  type RefObject,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export type RailScene =
  | "city"
  | "mountains"
  | "dunes"
  | "lake"
  | "islands"
  | "skyline"
  | "terraces"
  | "coast";

export interface RailItem {
  id: string;
  title: string;
  location: string;
  /** Photo URL, rendered with a plain <img>. Falls back to `scene`. */
  image?: string;
  /** Alt text for `image`. Empty by default: the title already names it. */
  imageAlt?: string;
  /** Built-in drawn artwork, used when there is no `image`. */
  scene?: RailScene;
  badge?: string;
  dates?: string;
  price: number;
  currency?: string;
  priceLabel?: string;
  rating?: number;
  reviewCount?: number;
  href?: string;
}

export type ToggleFavorite = (id: string, favorite: boolean) => void;

export interface CarouselCardsProps {
  items?: RailItem[];
  title?: string;
  eyebrow?: string;
  /** Ids saved on first render. */
  defaultFavorites?: string[];
  /** Called when a card's heart is toggled, with the item id and new state. */
  onToggleFavorite?: ToggleFavorite;
  /** Called when a card without an `href` is clicked or activated. */
  onSelect?: (item: RailItem) => void;
  className?: string;
}

const DEFAULT_ITEMS: RailItem[] = [
  {
    id: "lisbon",
    title: "Weekend in Lisbon",
    location: "Lisbon, Portugal",
    scene: "city",
    badge: "2 nights",
    dates: "Oct 24 – 26",
    price: 340,
    rating: 4.92,
    reviewCount: 318,
  },
  {
    id: "dolomites",
    title: "Slow days in the Dolomites",
    location: "Val Gardena, Italy",
    scene: "mountains",
    badge: "4 nights",
    dates: "Nov 3 – 7",
    price: 610,
    rating: 4.97,
    reviewCount: 142,
  },
  {
    id: "dunes",
    title: "Two nights in the dunes",
    location: "Merzouga, Morocco",
    scene: "dunes",
    badge: "2 nights",
    dates: "Nov 14 – 16",
    price: 280,
    rating: 4.88,
    reviewCount: 96,
  },
  {
    id: "lapland",
    title: "Lake cabin under the aurora",
    location: "Inari, Finland",
    scene: "lake",
    badge: "3 nights",
    dates: "Dec 5 – 8",
    price: 520,
    rating: 4.95,
    reviewCount: 210,
  },
  {
    id: "naxos",
    title: "Island hopping by ferry",
    location: "Naxos, Greece",
    scene: "islands",
    badge: "5 nights",
    dates: "May 9 – 14",
    price: 740,
    rating: 4.9,
    reviewCount: 187,
  },
  {
    id: "tokyo",
    title: "Late trains and night markets",
    location: "Tokyo, Japan",
    scene: "skyline",
    badge: "4 nights",
    dates: "Mar 20 – 24",
    price: 890,
    rating: 4.96,
    reviewCount: 402,
  },
  {
    id: "ubud",
    title: "Rice terraces at dawn",
    location: "Ubud, Indonesia",
    scene: "terraces",
    badge: "3 nights",
    dates: "Jan 12 – 15",
    price: 390,
    rating: 4.91,
    reviewCount: 133,
  },
  {
    id: "coast-road",
    title: "Coast road, windows down",
    location: "Big Sur, United States",
    scene: "coast",
    badge: "3 nights",
    dates: "Apr 2 – 5",
    price: 560,
    rating: 4.89,
    reviewCount: 158,
  },
];

/*
 * Depth runs off the main thread: each card is a view timeline on the inline
 * axis (0% entering on the right, 50% centered, 100% leaving on the left).
 * Browsers without scroll-driven animations get flat cards with every
 * detail visible. Reduced motion keeps only the details fade.
 */
const RAIL_CSS = `
@keyframes kokonutui-rail-tilt {
  0% { transform: perspective(900px) translateZ(-180px) rotateY(-14deg); }
  50% { transform: perspective(900px) translateZ(0) rotateY(0deg); }
  100% { transform: perspective(900px) translateZ(-180px) rotateY(14deg); }
}
@keyframes kokonutui-rail-parallax {
  from { transform: translate3d(calc(var(--rail-depth) * -1), 0, 0); }
  to { transform: translate3d(var(--rail-depth), 0, 0); }
}
@keyframes kokonutui-rail-details {
  0%, 32% { opacity: 0; transform: translate3d(0, 6px, 0); }
  45%, 55% { opacity: 1; transform: translate3d(0, 0, 0); }
  68%, 100% { opacity: 0; transform: translate3d(0, 6px, 0); }
}
@supports (animation-timeline: view()) {
  .kokonutui-rail-card { view-timeline: --kokonutui-rail inline; }
  .kokonutui-rail-details {
    animation: kokonutui-rail-details linear both;
    animation-timeline: --kokonutui-rail;
  }
  @media (prefers-reduced-motion: no-preference) {
    .kokonutui-rail-tilt {
      animation: kokonutui-rail-tilt linear both;
      animation-timeline: --kokonutui-rail;
    }
    .kokonutui-rail-layer {
      animation: kokonutui-rail-parallax linear both;
      animation-timeline: --kokonutui-rail;
    }
  }
}
`;

/* ------------------------------------------------------------------ */
/* Drawn scenes: flat zinc layers, each parallaxing by its own depth.  */
/* ------------------------------------------------------------------ */

const TONE = {
  sun: "fill-white dark:fill-zinc-400",
  far: "fill-zinc-300 dark:fill-zinc-800",
  mid: "fill-zinc-400 dark:fill-zinc-900",
  near: "fill-zinc-600 dark:fill-zinc-950",
  sky: "fill-zinc-200 dark:fill-zinc-700",
} as const;

interface SceneLayer {
  /** Parallax travel each way, as a share of the layer width. */
  depth: number;
  content: ReactNode;
}

const pines = (xs: number[], base: number, height: number) =>
  xs
    .map(
      (x, i) =>
        `M${x - 5} ${base}L${x} ${base - height - (i % 3) * 4}L${x + 5} ${base}Z`
    )
    .join("");

const windows = (
  x: number,
  y: number,
  cols: number,
  rows: number
): ReactNode[] => {
  const out: ReactNode[] = [];
  for (let r = 0; r < rows; r++) {
    for (let c = 0; c < cols; c++) {
      if ((r * 7 + c * 3) % 4 !== 0) {
        out.push(
          <rect
            className={TONE.sky}
            height="3"
            key={`${x}-${r}-${c}`}
            width="3"
            x={x + c * 7}
            y={y + r * 9}
          />
        );
      }
    }
  }
  return out;
};

const SCENES: Record<RailScene, SceneLayer[]> = {
  city: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="150" cy="56" r="16" />,
    },
    {
      depth: 4,
      content: (
        <path className={TONE.far} d="M0 128Q60 98 120 116T208 106V200H0Z" />
      ),
    },
    {
      depth: 7,
      content: (
        <path
          className={TONE.mid}
          d="M0 152H18V138L26 130L34 138V146H48V128H62V140H76V132L84 124L92 132V150H110V136H126V146H140V126L150 118L160 126V148H176V138H192V150H208V200H0Z"
        />
      ),
    },
    {
      depth: 11,
      content: (
        <>
          <path className={TONE.near} d="M0 180Q104 164 208 178V200H0Z" />
          <path
            className={TONE.near}
            d="M74 170V152Q74 148 78 148H118Q122 148 122 152V168Z"
          />
          <rect className={TONE.sky} height="7" width="8" x="80" y="152" />
          <rect className={TONE.sky} height="7" width="8" x="94" y="152" />
          <rect className={TONE.sky} height="7" width="8" x="108" y="152" />
        </>
      ),
    },
  ],
  mountains: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="54" cy="48" r="12" />,
    },
    {
      depth: 4,
      content: (
        <>
          <path
            className={TONE.far}
            d="M0 122L30 92L52 108L84 60L112 100L140 72L172 110L208 86V200H0Z"
          />
          <path className={TONE.sun} d="M74 75L84 60L94 75L88 71L83 77Z" />
          <path className={TONE.sun} d="M133 82L140 72L148 82L143 79Z" />
        </>
      ),
    },
    {
      depth: 7,
      content: (
        <path
          className={TONE.mid}
          d="M0 152L40 118L70 140L104 110L140 146L176 120L208 140V200H0Z"
        />
      ),
    },
    {
      depth: 11,
      content: (
        <path
          className={TONE.near}
          d={`M0 182Q60 164 120 174T208 168V200H0Z${pines([18, 30, 42, 162, 176, 190], 178, 20)}`}
        />
      ),
    },
  ],
  dunes: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="128" cy="66" r="22" />,
    },
    {
      depth: 4,
      content: (
        <path
          className={TONE.far}
          d="M0 128Q50 104 100 124Q150 142 208 112V200H0Z"
        />
      ),
    },
    {
      depth: 7,
      content: (
        <path
          className={TONE.mid}
          d="M0 158Q70 120 130 150Q170 168 208 146V200H0Z"
        />
      ),
    },
    {
      depth: 11,
      content: (
        <path
          className={TONE.near}
          d="M0 188Q40 160 96 176Q150 194 208 170V200H0Z"
        />
      ),
    },
  ],
  lake: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="160" cy="42" r="8" />,
    },
    {
      depth: 4,
      content: (
        <path
          className={TONE.far}
          d={`M0 142V130H208V142Z${pines([8, 20, 32, 44, 56, 68, 80, 92, 104, 116, 128, 140, 152, 164, 176, 188, 200], 132, 14)}`}
        />
      ),
    },
    {
      depth: 7,
      content: (
        <>
          <rect className={TONE.mid} height="58" width="208" x="0" y="142" />
          <path
            className={TONE.sky}
            d="M40 156H96V158H40ZM120 166H184V168H120ZM24 176H76V178H24Z"
          />
        </>
      ),
    },
    {
      depth: 11,
      content: (
        <>
          <path
            className={TONE.near}
            d="M0 184Q60 172 120 182T208 178V200H0Z"
          />
          <path className={TONE.near} d="M132 180V162L148 148L164 162V180Z" />
          <rect className={TONE.sun} height="6" width="6" x="145" y="166" />
        </>
      ),
    },
  ],
  islands: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="52" cy="54" r="14" />,
    },
    {
      depth: 4,
      content: (
        <>
          <rect className={TONE.mid} height="70" width="208" x="0" y="130" />
          <path className={TONE.far} d="M96 131Q130 104 176 126L188 131Z" />
          <path className={TONE.far} d="M10 131Q30 120 52 131Z" />
        </>
      ),
    },
    {
      depth: 7,
      content: (
        <>
          <path className={TONE.near} d="M52 160H88L82 167H58Z" />
          <path className={TONE.sun} d="M70 157V122L90 157Z" />
          <path className={TONE.sky} d="M66 157V130L54 157Z" />
          <path
            className={TONE.far}
            d="M20 178H60V180H20ZM110 172H170V174H110Z"
          />
        </>
      ),
    },
    {
      depth: 11,
      content: (
        <path
          className={TONE.near}
          d="M0 200V182Q20 170 44 180Q60 187 70 200ZM150 200Q170 176 208 176V200Z"
        />
      ),
    },
  ],
  skyline: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="40" cy="40" r="9" />,
    },
    {
      depth: 4,
      content: (
        <path
          className={TONE.far}
          d="M0 200V120H16V96H30V120H44V80H58V112H76V60H82V40H86V60H92V110H110V90H128V118H150V70H166V112H180V96H196V124H208V200Z"
        />
      ),
    },
    {
      depth: 7,
      content: (
        <>
          <path
            className={TONE.mid}
            d="M0 200V140H24V118H50V146H70V108H100V150H120V126H148V134H170V112H196V144H208V200Z"
          />
          {windows(74, 116, 3, 4)}
          {windows(174, 120, 3, 3)}
          {windows(28, 126, 3, 2)}
        </>
      ),
    },
    {
      depth: 11,
      content: (
        <path
          className={TONE.near}
          d="M0 170H208V178H0ZM10 178H18V200H10ZM70 178H78V200H70ZM130 178H138V200H130ZM190 178H198V200H190Z"
        />
      ),
    },
  ],
  terraces: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="104" cy="58" r="15" />,
    },
    {
      depth: 4,
      content: <path className={TONE.far} d="M0 108Q104 76 208 102V200H0Z" />,
    },
    {
      depth: 7,
      content: (
        <path
          className={TONE.mid}
          d="M0 136Q104 112 208 132V200H0ZM0 148Q104 126 208 146V150Q104 130 0 152ZM0 164Q104 142 208 162V166Q104 146 0 168Z"
        />
      ),
    },
    {
      depth: 11,
      content: (
        <path
          className={TONE.near}
          d="M0 184Q104 162 208 180V200H0ZM24 184Q20 166 27 148H30Q24 166 28 184ZM28 148Q15 140 6 148Q16 143 28 151ZM28 148Q41 138 51 146Q39 142 28 151ZM28 148Q23 134 12 132Q24 136 29 149ZM28 148Q35 134 45 132Q33 138 29 149Z"
        />
      ),
    },
  ],
  coast: [
    {
      depth: 2,
      content: <circle className={TONE.sun} cx="56" cy="92" r="13" />,
    },
    {
      depth: 4,
      content: (
        <>
          <rect className={TONE.mid} height="88" width="208" x="0" y="112" />
          <path className={TONE.far} d="M118 200V122Q150 96 208 98V200Z" />
        </>
      ),
    },
    {
      depth: 7,
      content: (
        <>
          <path
            className={TONE.near}
            d="M208 200V128Q172 132 150 160Q136 182 112 200Z"
          />
          <path
            className={TONE.sun}
            d="M208 146Q178 150 162 170Q150 186 136 200H140Q154 188 166 172Q182 154 208 150Z"
          />
        </>
      ),
    },
    {
      depth: 11,
      content: <path className={TONE.near} d="M0 200V172Q50 156 100 200Z" />,
    },
  ],
};

const LAYER_CLASS =
  "kokonutui-rail-layer absolute inset-y-0 -left-[15%] w-[130%]";

const Scene = ({ scene }: { scene: RailScene }) => (
  <div
    aria-hidden="true"
    className="absolute inset-0 bg-zinc-200 dark:bg-zinc-700"
  >
    {SCENES[scene].map((layer) => (
      <div
        className={LAYER_CLASS}
        key={layer.depth}
        style={{ "--rail-depth": `${layer.depth}%` } as CSSProperties}
      >
        <svg
          aria-hidden="true"
          className="h-full w-full"
          preserveAspectRatio="xMidYMax slice"
          viewBox="0 0 208 200"
        >
          {layer.content}
        </svg>
      </div>
    ))}
  </div>
);

/* ------------------------------------------------------------------ */
/* Heart: the fill rises from the base through a clip, no scale.       */
/* ------------------------------------------------------------------ */

const HEART =
  "M19 14c1.49-1.46 3-3.21 3-5.5A5.5 5.5 0 0 0 16.5 3c-1.76 0-3 .5-4.5 2-1.5-1.5-2.74-2-4.5-2A5.5 5.5 0 0 0 2 8.5c0 2.3 1.5 4.05 3 5.5l7 7Z";

const FavoriteButton = ({
  label,
  saved,
  onToggle,
}: {
  label: string;
  saved: boolean;
  onToggle: () => void;
}) => (
  <button
    aria-label={`Save ${label}`}
    aria-pressed={saved}
    className="absolute top-2.5 right-2.5 z-10 grid size-9 cursor-pointer place-items-center rounded-full bg-white text-zinc-900 shadow-sm ring-1 ring-black/5 transition-colors duration-150 ease-out hover:bg-zinc-100 focus-visible:outline-2 focus-visible:outline-zinc-900 focus-visible:outline-offset-2 dark:bg-zinc-950 dark:text-zinc-100 dark:ring-white/10 dark:focus-visible:outline-zinc-100 dark:hover:bg-zinc-900"
    onClick={onToggle}
    type="button"
  >
    <span className="relative size-[18px]">
      <svg
        aria-hidden="true"
        className={cn(
          "absolute inset-0 size-full transition-colors duration-200",
          saved && "text-rose-500"
        )}
        fill="none"
        stroke="currentColor"
        strokeLinejoin="round"
        strokeWidth="2"
        viewBox="0 0 24 24"
      >
        <path d={HEART} />
      </svg>
      <span
        className="absolute inset-0 transition-[clip-path] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none"
        style={{ clipPath: saved ? "inset(0 0 0 0)" : "inset(100% 0 0 0)" }}
      >
        <svg
          aria-hidden="true"
          className="size-full fill-rose-500 stroke-rose-500"
          strokeLinejoin="round"
          strokeWidth="2"
          viewBox="0 0 24 24"
        >
          <path d={HEART} />
        </svg>
      </span>
    </span>
  </button>
);

/* ------------------------------------------------------------------ */
/* Card                                                               */
/* ------------------------------------------------------------------ */

const CardDetails = ({ item }: { item: RailItem }) => (
  <div className="kokonutui-rail-details mt-2 flex items-center gap-1.5 text-xs">
    {item.rating !== undefined && (
      <span className="flex items-center gap-0.5 text-zinc-900 tabular-nums dark:text-zinc-100">
        <Star aria-hidden="true" className="size-3 fill-current" />
        {item.rating.toFixed(2)}
        {item.reviewCount !== undefined && (
          <span className="text-zinc-500 dark:text-zinc-400">
            ({item.reviewCount})
          </span>
        )}
      </span>
    )}
    {item.dates && (
      <span className="truncate text-zinc-500 dark:text-zinc-400">
        · {item.dates}
      </span>
    )}
    <span className="ml-auto shrink-0 font-medium text-zinc-900 tabular-nums dark:text-zinc-100">
      {item.currency ?? "€"}
      {item.price}
      <span className="font-normal text-zinc-500 dark:text-zinc-400">
        {" "}
        {item.priceLabel ?? "total"}
      </span>
    </span>
  </div>
);

const STRETCHED =
  "outline-none after:absolute after:inset-0 after:rounded-2xl after:content-['']";

const RailCard = ({
  item,
  saved,
  onToggleSaved,
  onSelect,
}: {
  item: RailItem;
  saved: boolean;
  onToggleSaved: (id: string) => void;
  onSelect?: (item: RailItem) => void;
}) => (
  <li className="kokonutui-rail-card w-(--rail-card) flex-none snap-center">
    <div className="kokonutui-rail-tilt group/rail-card relative">
      <div className="relative aspect-[4/5] overflow-hidden rounded-2xl bg-zinc-200 ring-zinc-900 ring-offset-2 ring-offset-white group-has-[[data-rail-link]:focus-visible]/rail-card:ring-2 dark:bg-zinc-800 dark:ring-zinc-100 dark:ring-offset-zinc-950">
        {item.image ? (
          <div className={cn(LAYER_CLASS, "[--rail-depth:8%]")}>
            {/* biome-ignore lint/performance/noImgElement: a plain img keeps the component free of next/image config */}
            <img
              alt={item.imageAlt ?? ""}
              className="h-full w-full object-cover"
              decoding="async"
              draggable={false}
              height={500}
              loading="lazy"
              src={item.image}
              width={520}
            />
          </div>
        ) : (
          <Scene scene={item.scene ?? "mountains"} />
        )}
        {item.badge && (
          <span className="absolute top-3 left-3 rounded-md bg-white px-1.5 py-0.5 font-medium text-[11px] text-zinc-900 shadow-sm dark:bg-zinc-950 dark:text-zinc-100">
            {item.badge}
          </span>
        )}
        <FavoriteButton
          label={item.title}
          onToggle={() => onToggleSaved(item.id)}
          saved={saved}
        />
      </div>

      <div className="px-0.5 pt-3">
        <h3 className="truncate font-medium text-sm text-zinc-900 tracking-tight dark:text-zinc-100">
          {/* The link is stretched over the card; the heart sits above it. */}
          {/* Without an href this is a button: a bare "#" link would navigate. */}
          {item.href ? (
            <a
              className={STRETCHED}
              data-rail-link=""
              draggable={false}
              href={item.href}
            >
              {item.title}
            </a>
          ) : (
            <button
              className={cn(STRETCHED, "cursor-pointer text-left")}
              data-rail-link=""
              onClick={() => onSelect?.(item)}
              type="button"
            >
              {item.title}
            </button>
          )}
        </h3>
        <p className="truncate text-xs text-zinc-500 dark:text-zinc-400">
          {item.location}
        </p>
        <CardDetails item={item} />
      </div>
    </div>
  </li>
);

/* ------------------------------------------------------------------ */
/* Momentum: drag, project, spring to a card, rubber-band at the ends. */
/* ------------------------------------------------------------------ */

const STIFFNESS = 170;
const DAMPING = 26; // about 2·√170: critically damped, so no bounce at the card
const DECELERATION = 0.997; // UIScrollView's normal rate, per ms
const DRAG_THRESHOLD = 4;

const rubber = (overshoot: number, size: number) =>
  Math.sign(overshoot) *
  (1 - 1 / ((Math.abs(overshoot) * 0.55) / size + 1)) *
  size;

const clamp = (v: number, min: number, max: number) =>
  Math.min(max, Math.max(min, v));

interface RailState {
  mode: "idle" | "pressing" | "dragging" | "spring";
  pointerId: number;
  startX: number;
  startPos: number;
  pos: number;
  vel: number;
  target: number;
  samples: { t: number; x: number }[];
  raf: number;
  last: number;
  suppressClick: boolean;
}

const maxScroll = (scroller: HTMLElement) =>
  scroller.scrollWidth - scroller.clientWidth;

const snapPoints = (scroller: HTMLElement, track: HTMLUListElement) => {
  const max = maxScroll(scroller);
  return Array.from(track.children, (child) => {
    const card = child as HTMLElement;
    const center = track.offsetLeft + card.offsetLeft + card.offsetWidth / 2;
    return clamp(center - scroller.clientWidth / 2, 0, max);
  });
};

const nearestIndex = (points: number[], pos: number) => {
  let best = 0;
  for (let i = 1; i < points.length; i++) {
    if (Math.abs(points[i] - pos) < Math.abs(points[best] - pos)) {
      best = i;
    }
  }
  return best;
};

// Release velocity in px/ms from the last 100ms of samples; a pause before
// letting go means no flick.
const releaseVelocity = (samples: RailState["samples"], now: number) => {
  const first = samples[0];
  const last = samples.at(-1) ?? first;
  const dt = last.t - first.t;
  if (dt <= 0 || now - last.t > 60) {
    return 0;
  }
  return -(last.x - first.x) / dt;
};

function useMomentumRail(
  scrollerRef: RefObject<HTMLElement | null>,
  trackRef: RefObject<HTMLUListElement | null>,
  onIndex: (index: number) => void
) {
  const state = useRef<RailState>({
    mode: "idle",
    pointerId: -1,
    startX: 0,
    startPos: 0,
    pos: 0,
    vel: 0,
    target: 0,
    samples: [],
    raf: 0,
    last: 0,
    suppressClick: false,
  });
  const onIndexRef = useRef(onIndex);
  onIndexRef.current = onIndex;

  // Write a virtual position: the in-range part scrolls natively, the rest
  // becomes a damped translate on the track (the rubber band).
  const apply = useCallback(
    (pos: number) => {
      const scroller = scrollerRef.current;
      const track = trackRef.current;
      if (!(scroller && track)) {
        return;
      }
      const inRange = clamp(pos, 0, maxScroll(scroller));
      scroller.scrollLeft = inRange;
      const over = pos - inRange;
      track.style.transform =
        Math.abs(over) > 0.1
          ? `translate3d(${(-rubber(over, scroller.clientWidth)).toFixed(2)}px,0,0)`
          : "";
    },
    [scrollerRef, trackRef]
  );

  // Native scroll snap is off while JS owns the position.
  const setFree = useCallback(
    (free: boolean) => {
      const scroller = scrollerRef.current;
      if (scroller) {
        scroller.dataset.free = String(free);
      }
    },
    [scrollerRef]
  );

  const step = useCallback(
    (now: number) => {
      const s = state.current;
      const dt = Math.min((now - s.last) / 1000, 1 / 30);
      s.last = now;
      // Semi-implicit Euler substeps keep the spring stable at any frame rate.
      const h = dt / 4;
      for (let i = 0; i < 4; i++) {
        const accel = -STIFFNESS * (s.pos - s.target) - DAMPING * s.vel;
        s.vel += accel * h;
        s.pos += s.vel * h;
      }
      if (Math.abs(s.pos - s.target) < 0.5 && Math.abs(s.vel) < 8) {
        s.pos = s.target;
        s.vel = 0;
        s.mode = "idle";
        apply(s.target);
        setFree(false);
        return;
      }
      apply(s.pos);
      s.raf = requestAnimationFrame(step);
    },
    [apply, setFree]
  );

  const springTo = useCallback(
    (target: number, velocity: number) => {
      const s = state.current;
      const scroller = scrollerRef.current;
      if (!scroller) {
        return;
      }
      cancelAnimationFrame(s.raf);
      if (s.mode !== "spring" && s.mode !== "dragging") {
        s.pos = scroller.scrollLeft;
      }
      s.target = target;
      s.vel = velocity;
      if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
        s.mode = "idle";
        s.pos = target;
        apply(target);
        setFree(false);
        return;
      }
      s.mode = "spring";
      setFree(true);
      s.last = performance.now();
      s.raf = requestAnimationFrame(step);
    },
    [apply, scrollerRef, setFree, step]
  );

  const goTo = useCallback(
    (index: number) => {
      const scroller = scrollerRef.current;
      const track = trackRef.current;
      if (!(scroller && track)) {
        return;
      }
      const s = state.current;
      const points = snapPoints(scroller, track);
      const i = clamp(index, 0, points.length - 1);
      springTo(points[i], s.mode === "spring" ? s.vel : 0);
    },
    [scrollerRef, springTo, trackRef]
  );

  const currentIndex = useCallback(() => {
    const scroller = scrollerRef.current;
    const track = trackRef.current;
    if (!(scroller && track)) {
      return 0;
    }
    const s = state.current;
    const pos = s.mode === "spring" ? s.target : scroller.scrollLeft;
    return nearestIndex(snapPoints(scroller, track), pos);
  }, [scrollerRef, trackRef]);

  useEffect(() => {
    const scroller = scrollerRef.current;
    const track = trackRef.current;
    if (!(scroller && track)) {
      return;
    }
    const s = state.current;
    let scrollRaf = 0;

    const onScroll = () => {
      cancelAnimationFrame(scrollRaf);
      scrollRaf = requestAnimationFrame(() => {
        onIndexRef.current(
          nearestIndex(snapPoints(scroller, track), scroller.scrollLeft)
        );
      });
    };

    const onPointerDown = (e: PointerEvent) => {
      if (e.pointerType !== "mouse" || e.button !== 0) {
        return;
      }
      if ((e.target as Element).closest("button:not([data-rail-link])")) {
        return;
      }
      cancelAnimationFrame(s.raf);
      // Catching a moving rail keeps its virtual position, overshoot included.
      s.pos = s.mode === "spring" ? s.pos : scroller.scrollLeft;
      s.mode = "pressing";
      s.pointerId = e.pointerId;
      s.startX = e.clientX;
      s.startPos = s.pos;
      s.samples = [{ t: e.timeStamp, x: e.clientX }];
    };

    const onPointerMove = (e: PointerEvent) => {
      if (e.pointerId !== s.pointerId) {
        return;
      }
      const dx = e.clientX - s.startX;
      if (s.mode === "pressing" && Math.abs(dx) > DRAG_THRESHOLD) {
        s.mode = "dragging";
        scroller.setPointerCapture(e.pointerId);
        scroller.dataset.dragging = "true";
        setFree(true);
      }
      if (s.mode !== "dragging") {
        return;
      }
      s.pos = s.startPos - dx;
      apply(s.pos);
      s.samples.push({ t: e.timeStamp, x: e.clientX });
      while (s.samples.length > 2 && e.timeStamp - s.samples[0].t > 100) {
        s.samples.shift();
      }
    };

    const onRelease = (e: PointerEvent) => {
      if (e.pointerId !== s.pointerId) {
        return;
      }
      s.pointerId = -1;
      if (s.mode !== "dragging") {
        // A press that never became a drag hands back to native snapping.
        s.mode = "idle";
        setFree(false);
        return;
      }
      scroller.dataset.dragging = "false";
      s.suppressClick = true;
      setTimeout(() => {
        s.suppressClick = false;
      }, 0);
      const v = releaseVelocity(s.samples, e.timeStamp);
      const projected = s.pos + (v * DECELERATION) / (1 - DECELERATION);
      const points = snapPoints(scroller, track);
      springTo(points[nearestIndex(points, projected)], v * 1000);
    };

    // A drag that ends over a card must not follow its link.
    const onClickCapture = (e: MouseEvent) => {
      if (s.suppressClick) {
        e.preventDefault();
        e.stopPropagation();
        s.suppressClick = false;
      }
    };

    // Wheel or touch takes over from a running spring.
    const onNativeInput = () => {
      if (s.mode !== "spring") {
        return;
      }
      cancelAnimationFrame(s.raf);
      s.mode = "idle";
      apply(clamp(s.pos, 0, maxScroll(scroller)));
      setFree(false);
    };

    // Arrow keys step one card; Home and End jump to the ends.
    const onKeyDown = (e: KeyboardEvent) => {
      if (e.target !== scroller) {
        return;
      }
      const last = track.children.length - 1;
      const index = nearestIndex(
        snapPoints(scroller, track),
        s.mode === "spring" ? s.target : scroller.scrollLeft
      );
      let next = -1;
      switch (e.key) {
        case "ArrowLeft":
          next = index - 1;
          break;
        case "ArrowRight":
          next = index + 1;
          break;
        case "Home":
          next = 0;
          break;
        case "End":
          next = last;
          break;
        default:
          return;
      }
      e.preventDefault();
      goTo(next);
    };

    scroller.addEventListener("keydown", onKeyDown);
    scroller.addEventListener("scroll", onScroll, { passive: true });
    scroller.addEventListener("pointerdown", onPointerDown);
    scroller.addEventListener("pointermove", onPointerMove);
    scroller.addEventListener("pointerup", onRelease);
    scroller.addEventListener("pointercancel", onRelease);
    scroller.addEventListener("lostpointercapture", onRelease);
    scroller.addEventListener("click", onClickCapture, true);
    scroller.addEventListener("wheel", onNativeInput, { passive: true });
    scroller.addEventListener("touchstart", onNativeInput, { passive: true });
    return () => {
      cancelAnimationFrame(scrollRaf);
      cancelAnimationFrame(s.raf);
      scroller.removeEventListener("keydown", onKeyDown);
      scroller.removeEventListener("scroll", onScroll);
      scroller.removeEventListener("pointerdown", onPointerDown);
      scroller.removeEventListener("pointermove", onPointerMove);
      scroller.removeEventListener("pointerup", onRelease);
      scroller.removeEventListener("pointercancel", onRelease);
      scroller.removeEventListener("lostpointercapture", onRelease);
      scroller.removeEventListener("click", onClickCapture, true);
      scroller.removeEventListener("wheel", onNativeInput);
      scroller.removeEventListener("touchstart", onNativeInput);
    };
  }, [apply, goTo, scrollerRef, setFree, springTo, trackRef]);

  return { goTo, currentIndex };
}

/* ------------------------------------------------------------------ */
/* Rail                                                               */
/* ------------------------------------------------------------------ */

// `aria-disabled` rather than `disabled` at the ends, so focus stays put.
const ARROW_CLASS =
  "grid size-8 cursor-pointer place-items-center rounded-full border border-zinc-200 bg-white text-zinc-900 transition-[background-color,opacity] duration-150 ease-out hover:bg-zinc-100 focus-visible:outline-2 focus-visible:outline-zinc-900 focus-visible:outline-offset-2 aria-disabled:cursor-default aria-disabled:opacity-40 aria-disabled:hover:bg-white dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100 dark:aria-disabled:hover:bg-zinc-950 dark:focus-visible:outline-zinc-100 dark:hover:bg-zinc-900";

export default function CarouselCards({
  items = DEFAULT_ITEMS,
  title = "Weekend escapes",
  eyebrow = "Picked for this autumn",
  defaultFavorites = [],
  onToggleFavorite,
  onSelect,
  className,
}: CarouselCardsProps) {
  const scrollerRef = useRef<HTMLElement>(null);
  const trackRef = useRef<HTMLUListElement>(null);
  const [active, setActive] = useState(0);
  const [saved, setSaved] = useState<ReadonlySet<string>>(
    () => new Set(defaultFavorites)
  );
  const { goTo, currentIndex } = useMomentumRail(
    scrollerRef,
    trackRef,
    setActive
  );

  const toggleSaved = (id: string) => {
    const next = !saved.has(id);
    setSaved((prev) => {
      const copy = new Set(prev);
      if (next) {
        copy.add(id);
      } else {
        copy.delete(id);
      }
      return copy;
    });
    onToggleFavorite?.(id, next);
  };

  const step = (delta: number) => goTo(currentIndex() + delta);

  return (
    <section
      aria-label={title}
      aria-roledescription="carousel"
      className={cn(
        "@container/rail w-full py-4 @3xl/rail:[--rail-card:16rem] @md/rail:[--rail-card:15rem] [--rail-card:13.5rem]",
        className
      )}
    >
      <div className="mb-2 flex items-end justify-between gap-4 px-4">
        <div className="min-w-0">
          <p className="text-xs text-zinc-500 dark:text-zinc-400">{eyebrow}</p>
          <h2 className="truncate font-semibold text-lg text-zinc-900 tracking-tight dark:text-zinc-100">
            {title}
          </h2>
        </div>
        <div className="flex shrink-0 items-center gap-2">
          <span
            aria-live="polite"
            className="mr-1 text-xs text-zinc-500 tabular-nums dark:text-zinc-400"
          >
            <span className="sr-only">Card </span>
            {String(active + 1).padStart(2, "0")}
            <span aria-hidden="true"> / </span>
            <span className="sr-only"> of </span>
            {String(items.length).padStart(2, "0")}
          </span>
          <button
            aria-disabled={active === 0}
            aria-label="Previous"
            className={ARROW_CLASS}
            onClick={() => step(-1)}
            type="button"
          >
            <ChevronLeft aria-hidden="true" className="size-4" />
          </button>
          <button
            aria-disabled={active === items.length - 1}
            aria-label="Next"
            className={ARROW_CLASS}
            onClick={() => step(1)}
            type="button"
          >
            <ChevronRight aria-hidden="true" className="size-4" />
          </button>
        </div>
      </div>

      <section
        aria-label={`${title}, use arrow keys to move`}
        className="relative snap-x snap-mandatory overflow-x-auto overscroll-x-contain py-6 outline-none [scrollbar-width:none] focus-visible:ring-2 focus-visible:ring-zinc-900 focus-visible:ring-inset data-[dragging=true]:cursor-grabbing data-[free=true]:snap-none dark:focus-visible:ring-zinc-100 [&::-webkit-scrollbar]:hidden [@media(pointer:fine)]:cursor-grab [@media(pointer:fine)]:select-none"
        ref={scrollerRef}
        // biome-ignore lint/a11y/noNoninteractiveTabindex: a focusable scroller is how keyboard users reach the arrow keys
        tabIndex={0}
      >
        <ul
          className="relative flex w-max gap-4 px-[calc(50cqw-var(--rail-card)/2)]"
          ref={trackRef}
        >
          {items.map((item) => (
            <RailCard
              item={item}
              key={item.id}
              onSelect={onSelect}
              onToggleSaved={toggleSaved}
              saved={saved.has(item.id)}
            />
          ))}
        </ul>
      </section>

      <style href="kokonutui-carousel-cards" precedence="default">
        {RAIL_CSS}
      </style>
    </section>
  );
}
```


---

# Currency Transfer
> Currency transfer card with odometer amounts, a live rate, a chip that carries the money across and a progress arc, built with React and Motion.

Source: https://kokonutui.com/docs/cards/currency-transfer

## Installation

```bash
npx shadcn@latest add @kokonutui/currency-transfer
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Currency Transfer
 * @version: 2.1.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  ArrowDownIcon,
  ArrowUpDown,
  ArrowUpIcon,
  InfoIcon,
  XIcon,
} from "lucide-react";
import {
  AnimatePresence,
  motion,
  type Transition,
  useReducedMotion,
  type Variants,
} from "motion/react";
import { type RefObject, useEffect, useRef, useState } from "react";
import { Card, CardContent } from "@/components/ui/card";
import {
  Tooltip,
  TooltipContent,
  TooltipProvider,
  TooltipTrigger,
} from "@/components/ui/tooltip";
import { cn } from "@/lib/utils";

export type TransferStatus = "processing" | "completed" | "failed";

export interface TransferAccount {
  /** Amount sent from / received into this account. */
  amount: number;
  /** ISO currency code, e.g. "USD". */
  currency: string;
  /** Short symbol shown in the badge, e.g. "$". Defaults to the currency's own symbol. */
  symbol?: string;
  /** Bank or account name, e.g. "Chase Bank". */
  bank: string;
  /** Last digits of the account number, shown masked. */
  last4?: string;
}

export interface CurrencyTransferProps {
  from?: TransferAccount;
  to?: TransferAccount;
  /** Units of `to.currency` per one unit of `from.currency`. */
  rate?: number;
  /** Transaction reference shown once the transfer completes. */
  txnId?: string;
  /** When the exchange rate was set, shown in the info tooltip (e.g. "10:45 AM"). */
  timestamp?: string;
  /**
   * Controlled status. When omitted, the card runs a demo: it starts as
   * "processing" and completes on its own after a short delay.
   */
  status?: TransferStatus;
  /** BCP 47 locale for amounts, symbols and the rate. */
  locale?: string;
  className?: string;
}

const DEFAULT_FROM: TransferAccount = {
  amount: 500,
  currency: "USD",
  symbol: "$",
  bank: "Chase Bank",
  last4: "4589",
};

const DEFAULT_TO: TransferAccount = {
  amount: 460,
  currency: "EUR",
  symbol: "€",
  bank: "Deutsche Bank",
  last4: "7823",
};

const DEMO_COMPLETE_DELAY_MS = 2600;

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const EASE_IN_OUT = [0.77, 0, 0.175, 1] as const;
const EASE_OUT_CSS = "cubic-bezier(0.23, 1, 0.32, 1)";
const EASE_IN_OUT_CSS = "cubic-bezier(0.77, 0, 0.175, 1)";

// While processing, the live rate wobbles by up to this fraction, this often.
const RATE_TICK_MS = 750;
const RATE_WOBBLE = 0.0008;
// The currency chip's trip from the From row to the To row.
const CHIP_MS = 600;
// Each digit column starts this much after the one to its right.
const DIGIT_STAGGER_MS = 40;
const DIGIT_ROLL_MS = 600;
// Progress arc: creeps towards 85% while processing, closes on completion.
const ARC_PENDING = 0.85;
const ARC_PENDING_MS = 4000;
const ARC_RADIUS = 48;
const ARC_LENGTH = 2 * Math.PI * ARC_RADIUS;

function formatNumber(value: number, locale: string, digits: number) {
  return new Intl.NumberFormat(locale, {
    minimumFractionDigits: digits,
    maximumFractionDigits: digits,
  }).format(value);
}

function getCurrencySymbol(currency: string, locale: string) {
  try {
    const parts = new Intl.NumberFormat(locale, {
      style: "currency",
      currency,
      currencyDisplay: "narrowSymbol",
    }).formatToParts(0);
    return (
      parts.find((part) => part.type === "currency")?.value ??
      currency.charAt(0)
    );
  } catch {
    // Not an ISO 4217 code.
    return currency.charAt(0);
  }
}

const symbolOf = (account: TransferAccount, locale: string) =>
  account.symbol ?? getCurrencySymbol(account.currency, locale);

/** Text that swaps between states: short rise in, short rise out. */
const swapVariants: Variants = {
  initial: { opacity: 0, y: 6 },
  animate: { opacity: 1, y: 0, transition: { duration: 0.2, ease: EASE_OUT } },
  exit: { opacity: 0, y: -6, transition: { duration: 0.15, ease: EASE_OUT } },
};

/**
 * Same swap without movement, for prefers-reduced-motion. `y` and `scale` are
 * pinned at rest so the server (which can't know the preference) and the
 * client render the same transform.
 */
const fadeVariants: Variants = {
  initial: { opacity: 0, y: 0, scale: 1 },
  animate: {
    opacity: 1,
    y: 0,
    scale: 1,
    transition: { duration: 0.2, ease: EASE_OUT },
  },
  exit: {
    opacity: 0,
    y: 0,
    scale: 1,
    transition: { duration: 0.15, ease: EASE_OUT },
  },
};

/** Status icon swap: never from scale(0), a slight 0.9 -> 1 settle. */
const iconVariants: Variants = {
  initial: { opacity: 0, scale: 0.9 },
  animate: {
    opacity: 1,
    scale: 1,
    transition: { duration: 0.25, ease: EASE_OUT },
  },
  exit: {
    opacity: 0,
    scale: 0.9,
    transition: { duration: 0.15, ease: EASE_OUT },
  },
};

/**
 * An odometer: each digit is a 0-9 strip in a one-digit window, moved with
 * translateY. Columns are keyed from the right so a changing length keeps
 * them aligned, and the right-most column moves first.
 */
function RollingNumber({ value }: { value: string }) {
  const chars = Array.from(value);
  return (
    <>
      <span className="sr-only">{value}</span>
      <span aria-hidden="true" className="inline-flex select-none tabular-nums">
        {chars.map((char, index) => {
          const fromRight = chars.length - index;
          const digit = Number.parseInt(char, 10);
          if (Number.isNaN(digit)) {
            return <span key={`s-${fromRight}`}>{char}</span>;
          }
          return (
            <span
              className="relative inline-block h-[1lh] overflow-hidden"
              key={`d-${fromRight}`}
            >
              {/* Sizes the window to one digit. */}
              <span className="invisible">0</span>
              <span
                // Reduced motion is handled in CSS: the server can't know the
                // preference, so it must not change the markup.
                className="absolute inset-x-0 top-0 flex flex-col motion-reduce:transition-none!"
                style={{
                  transform: `translateY(${-digit * 10}%)`,
                  transition: `transform ${DIGIT_ROLL_MS}ms ${EASE_OUT_CSS} ${(fromRight - 1) * DIGIT_STAGGER_MS}ms`,
                }}
              >
                {"0123456789".split("").map((n) => (
                  <span className="h-[1lh]" key={n}>
                    {n}
                  </span>
                ))}
              </span>
            </span>
          );
        })}
      </span>
    </>
  );
}

interface AccountRowProps {
  direction: "from" | "to";
  account: TransferAccount;
  /** The amount shown; the To row shows zero until the money lands. */
  amount: number;
  /** Rows join once the money has landed. */
  joined: boolean;
  /** Full colour once the amount is final. */
  settled: boolean;
  locale: string;
  reduceMotion: boolean;
  badgeRef: RefObject<HTMLSpanElement | null>;
}

function AccountRow({
  direction,
  account,
  amount,
  joined,
  settled,
  locale,
  reduceMotion,
  badgeRef,
}: AccountRowProps) {
  const isFrom = direction === "from";
  const DirectionIcon = isFrom ? ArrowUpIcon : ArrowDownIcon;
  // The two rows sit 12px apart; once joined each moves 6px toward the
  // other so they form one block (transform only, no layout animation).
  const joinOffset = isFrom ? 6 : -6;
  const transition: Transition = reduceMotion
    ? { duration: 0 }
    : { duration: 0.3, ease: EASE_IN_OUT };
  // The facing corners square off once the rows meet, not as they start
  // moving; they round again as soon as the rows start to part.
  const [hasMet, setHasMet] = useState(joined);
  const squared = joined && hasMet;

  return (
    <motion.div
      animate={{ y: joined ? joinOffset : 0 }}
      className={cn(
        "w-full rounded-xl border border-zinc-200 bg-zinc-50 p-2.5 dark:border-zinc-700/50 dark:bg-zinc-800/50",
        squared && isFrom && "rounded-b-none border-b-0",
        squared && !isFrom && "rounded-t-none border-t-0"
      )}
      initial={false}
      onAnimationComplete={() => setHasMet(joined)}
      transition={transition}
    >
      <div className="w-full space-y-1">
        <span className="flex items-center gap-1.5 font-medium text-xs text-zinc-500 dark:text-zinc-400">
          <DirectionIcon aria-hidden="true" className="h-3 w-3" />
          {isFrom ? "From" : "To"}
        </span>
        <div className="flex items-center gap-2.5">
          <span
            aria-hidden="true"
            className={cn(
              "inline-flex h-7 w-7 items-center justify-center rounded-lg border bg-white font-medium text-sm text-zinc-900 transition-colors duration-300 dark:bg-zinc-900 dark:text-zinc-100",
              !isFrom && settled
                ? "border-emerald-500/70"
                : "border-zinc-300 dark:border-zinc-700"
            )}
            ref={badgeRef}
          >
            {symbolOf(account, locale)}
          </span>
          <div className="flex flex-col items-start">
            <span
              className={cn(
                "font-medium tracking-tight transition-colors duration-200",
                settled
                  ? "text-zinc-900 dark:text-zinc-100"
                  : "text-zinc-500 dark:text-zinc-400"
              )}
            >
              <RollingNumber value={formatNumber(amount, locale, 2)} />{" "}
              {account.currency}
            </span>
            <span className="text-xs text-zinc-500 dark:text-zinc-400">
              {account.bank}
              {account.last4 ? ` ••••${account.last4}` : null}
            </span>
          </div>
        </div>
      </div>
    </motion.div>
  );
}

/**
 * The progress arc stands in for a spinner: it eases towards 85% while the
 * transfer is processing (an honest "almost"), then closes on completion.
 * On failure it turns red and only this badge shakes.
 */
function StatusBadge({
  status,
  reduceMotion,
}: {
  status: TransferStatus;
  reduceMotion: boolean;
}) {
  const badgeRef = useRef<HTMLDivElement>(null);
  // Starts empty on the server; the creep towards 85% begins on mount, and
  // again from empty each time the transfer goes back to processing (a
  // retry), instead of the arc unwinding from full.
  const [armed, setArmed] = useState(status !== "processing");
  const [armedFor, setArmedFor] = useState(status);
  if (armedFor !== status) {
    setArmedFor(status);
    if (status === "processing") {
      setArmed(false);
    }
  }
  useEffect(() => {
    if (armed) {
      return;
    }
    // Two frames: the empty arc has to be painted before the creep starts,
    // or the browser has nothing to transition from.
    let frame = requestAnimationFrame(() => {
      frame = requestAnimationFrame(() => setArmed(true));
    });
    return () => cancelAnimationFrame(frame);
  }, [armed]);

  const previous = useRef(status);
  useEffect(() => {
    const was = previous.current;
    previous.current = status;
    if (status !== "failed" || was === "failed" || reduceMotion) {
      return;
    }
    badgeRef.current?.animate(
      [
        { transform: "translateX(0)" },
        { transform: "translateX(-7px)" },
        { transform: "translateX(6px)" },
        { transform: "translateX(-4px)" },
        { transform: "translateX(2px)" },
        { transform: "translateX(0)" },
      ],
      { duration: 420, easing: "ease-out" }
    );
  }, [status, reduceMotion]);

  let progress = 1;
  let arcTransition = `stroke-dashoffset 350ms ${EASE_OUT_CSS}, color 200ms ease`;
  if (status === "processing") {
    progress = armed ? ARC_PENDING : 0;
    // Snap back to empty, then creep.
    arcTransition = armed
      ? `stroke-dashoffset ${ARC_PENDING_MS}ms cubic-bezier(0.1, 0.7, 0.3, 1)`
      : "none";
  }

  return (
    <div
      className="relative flex h-[100px] w-[100px] items-center justify-center"
      ref={badgeRef}
    >
      <svg
        aria-hidden="true"
        className="absolute inset-0 -rotate-90 [&_circle]:motion-reduce:transition-none!"
        height="100"
        viewBox="0 0 100 100"
        width="100"
      >
        <circle
          className="text-zinc-200 dark:text-zinc-800"
          cx="50"
          cy="50"
          fill="none"
          r={ARC_RADIUS}
          stroke="currentColor"
          strokeWidth="2.5"
        />
        <circle
          className={
            status === "failed"
              ? "text-red-500"
              : "text-emerald-500 dark:text-emerald-400"
          }
          cx="50"
          cy="50"
          fill="none"
          r={ARC_RADIUS}
          stroke="currentColor"
          strokeDasharray={ARC_LENGTH}
          strokeLinecap="round"
          strokeWidth="2.5"
          style={{
            strokeDashoffset: (1 - progress) * ARC_LENGTH,
            transition: arcTransition,
          }}
        />
      </svg>
      <AnimatePresence initial={false} mode="wait">
        <motion.div
          animate="animate"
          className="relative rounded-full p-5"
          exit="exit"
          initial="initial"
          key={status}
          variants={reduceMotion ? fadeVariants : iconVariants}
        >
          {status === "failed" && (
            <XIcon
              aria-hidden="true"
              className="h-10 w-10 text-red-500"
              strokeWidth={3}
            />
          )}
          {status === "completed" && (
            <svg
              aria-hidden="true"
              className="h-10 w-10 text-emerald-500 dark:text-emerald-400"
              fill="none"
              stroke="currentColor"
              strokeLinecap="round"
              strokeLinejoin="round"
              strokeWidth={3}
              viewBox="0 0 24 24"
            >
              <motion.path
                animate={{ pathLength: 1 }}
                d="M20 6 9 17l-5-5"
                initial={{ pathLength: reduceMotion ? 1 : 0 }}
                transition={{ duration: 0.3, delay: 0.15, ease: EASE_OUT }}
              />
            </svg>
          )}
          {status === "processing" && (
            <ArrowUpDown
              aria-hidden="true"
              className="h-10 w-10 text-emerald-500 dark:text-emerald-400"
            />
          )}
        </motion.div>
      </AnimatePresence>
    </div>
  );
}

const TITLES: Record<TransferStatus, string> = {
  processing: "Transfer in Progress",
  completed: "Transfer Completed",
  failed: "Transfer Failed",
};

/**
 * Wobbles the rate a little while the transfer is processing, as a live
 * quote would, and settles back on the agreed rate otherwise.
 */
function useLiveRate(rate: number, processing: boolean, reduceMotion: boolean) {
  const [live, setLive] = useState(rate);
  useEffect(() => {
    setLive(rate);
    if (!processing || reduceMotion) {
      return;
    }
    const timer = window.setInterval(() => {
      setLive(rate * (1 + (Math.random() * 2 - 1) * RATE_WOBBLE));
    }, RATE_TICK_MS);
    return () => window.clearInterval(timer);
  }, [rate, processing, reduceMotion]);
  return live;
}

/**
 * Plays the currency chip's trip from the From badge to the To badge when
 * the transfer completes. `landed` turns true when it arrives (at once
 * with reduced motion, or when the card first renders as completed).
 */
function useChipFlight(
  completed: boolean,
  reduceMotion: boolean,
  refs: {
    area: RefObject<HTMLDivElement | null>;
    fromBadge: RefObject<HTMLSpanElement | null>;
    toBadge: RefObject<HTMLSpanElement | null>;
    chip: RefObject<HTMLSpanElement | null>;
  }
) {
  const [landed, setLanded] = useState(completed);
  const { area, fromBadge, toBadge, chip } = refs;
  useEffect(() => {
    if (!completed) {
      setLanded(false);
      return;
    }
    const node = chip.current;
    const box = area.current?.getBoundingClientRect();
    const start = fromBadge.current?.getBoundingClientRect();
    const end = toBadge.current?.getBoundingClientRect();
    if (reduceMotion || !(node && box && start && end)) {
      setLanded(true);
      return;
    }
    node.style.left = `${start.left - box.left}px`;
    node.style.top = `${start.top - box.top}px`;
    const dy = end.top - start.top;
    // A slight bow to the right, as if handed over, not slid down a rail.
    const flight = node.animate(
      [
        { transform: "translate(0, 0)", opacity: 0, offset: 0 },
        { transform: "translate(0, 0)", opacity: 1, offset: 0.08 },
        {
          transform: `translate(14px, ${dy * 0.5}px)`,
          opacity: 1,
          offset: 0.5,
        },
        { transform: `translate(0, ${dy}px)`, opacity: 1, offset: 0.92 },
        { transform: `translate(0, ${dy}px)`, opacity: 0, offset: 1 },
      ],
      { duration: CHIP_MS, easing: EASE_IN_OUT_CSS }
    );
    // The symbol changes currency on the way.
    const [fromSymbol, toSymbol] = Array.from(node.children);
    const swap = { duration: CHIP_MS, easing: "linear" };
    fromSymbol?.animate(
      [
        { opacity: 1 },
        { opacity: 1, offset: 0.4 },
        { opacity: 0, offset: 0.6 },
      ],
      swap
    );
    toSymbol?.animate(
      [
        { opacity: 0 },
        { opacity: 0, offset: 0.4 },
        { opacity: 1, offset: 0.6 },
        { opacity: 1 },
      ],
      swap
    );
    let cancelled = false;
    flight.finished
      .then(() => {
        if (!cancelled) {
          setLanded(true);
        }
      })
      .catch(() => {
        // Cancelled by unmount.
      });
    return () => {
      cancelled = true;
      flight.cancel();
    };
  }, [completed, reduceMotion, area, fromBadge, toBadge, chip]);
  return landed && completed;
}

export default function CurrencyTransfer({
  from = DEFAULT_FROM,
  to = DEFAULT_TO,
  rate = 0.92,
  txnId = "TXN-DAB3UL494",
  timestamp = "10:45 AM",
  status,
  locale = "en-US",
  className,
}: CurrencyTransferProps = {}) {
  const reduceMotion = useReducedMotion() ?? false;
  const isControlled = status !== undefined;
  const [demoStatus, setDemoStatus] = useState<TransferStatus>("processing");
  const currentStatus = status ?? demoStatus;
  const completed = currentStatus === "completed";
  const failed = currentStatus === "failed";
  const processing = currentStatus === "processing";

  const liveRate = useLiveRate(rate, processing, reduceMotion);
  const areaRef = useRef<HTMLDivElement>(null);
  const fromBadgeRef = useRef<HTMLSpanElement>(null);
  const toBadgeRef = useRef<HTMLSpanElement>(null);
  const chipRef = useRef<HTMLSpanElement>(null);
  const landed = useChipFlight(completed, reduceMotion, {
    area: areaRef,
    fromBadge: fromBadgeRef,
    toBadge: toBadgeRef,
    chip: chipRef,
  });
  // Nothing has arrived until the chip lands; then the amount rolls up.
  const toAmount = landed ? to.amount : 0;

  // Demo mode only: auto-complete after a short delay. Controlled usage
  // (status passed in) never starts a timer.
  useEffect(() => {
    if (isControlled) {
      return;
    }
    const timer = setTimeout(() => {
      setDemoStatus("completed");
    }, DEMO_COMPLETE_DELAY_MS);
    return () => clearTimeout(timer);
  }, [isControlled]);

  const swap = reduceMotion ? fadeVariants : swapVariants;
  // The hidden pose is the same on server and client; reduced motion drops
  // the rise by giving `y` no duration.
  const entry: Variants = {
    hidden: { opacity: 0, y: 8 },
    visible: (i: number) => ({
      opacity: 1,
      y: 0,
      transition: {
        duration: 0.25,
        delay: i * 0.06,
        ease: EASE_OUT,
        y: reduceMotion ? { duration: 0 } : undefined,
      },
    }),
  };

  return (
    <TooltipProvider>
      {/* Sized by its content, so the icon and rows no longer overflow
          fixed slots into the card's padding. */}
      <Card
        className={cn(
          "mx-auto flex w-full max-w-sm flex-col border border-zinc-200/60 bg-white p-6 dark:border-zinc-800/60 dark:bg-zinc-900",
          className
        )}
      >
        <CardContent className="flex flex-1 flex-col justify-center space-y-4 py-0">
          <output aria-live="polite" className="sr-only">
            {completed && `Transfer completed. Transaction ID ${txnId}.`}
            {failed && "Transfer failed."}
            {processing && "Transfer in progress."}
          </output>

          <motion.div
            animate="visible"
            className="flex items-center justify-center"
            custom={0}
            initial="hidden"
            variants={entry}
          >
            <StatusBadge reduceMotion={reduceMotion} status={currentStatus} />
          </motion.div>

          <motion.div
            animate="visible"
            className="flex flex-col"
            custom={1}
            initial="hidden"
            variants={entry}
          >
            <div className="w-full space-y-2 text-center">
              <AnimatePresence initial={false} mode="wait">
                <motion.h2
                  animate="animate"
                  className="font-semibold text-lg text-zinc-900 uppercase tracking-wide dark:text-zinc-100"
                  exit="exit"
                  initial="initial"
                  key={`${currentStatus}-title`}
                  variants={swap}
                >
                  {TITLES[currentStatus]}
                </motion.h2>
              </AnimatePresence>
              <AnimatePresence initial={false} mode="wait">
                <motion.div
                  animate="animate"
                  className={cn(
                    "font-medium text-xs",
                    failed
                      ? "text-red-600 dark:text-red-400"
                      : "text-emerald-600 dark:text-emerald-400"
                  )}
                  exit="exit"
                  initial="initial"
                  key={`${currentStatus}-detail`}
                  variants={swap}
                >
                  {completed && `Transaction ID: ${txnId}`}
                  {failed && "Please try again"}
                  {processing && "Processing Transaction..."}
                </motion.div>
              </AnimatePresence>

              <div
                className="relative mt-4 flex flex-col items-start gap-3"
                ref={areaRef}
              >
                <AccountRow
                  account={from}
                  amount={from.amount}
                  badgeRef={fromBadgeRef}
                  direction="from"
                  joined={landed}
                  locale={locale}
                  reduceMotion={reduceMotion}
                  settled={landed}
                />
                <AccountRow
                  account={to}
                  amount={toAmount}
                  badgeRef={toBadgeRef}
                  direction="to"
                  joined={landed}
                  locale={locale}
                  reduceMotion={reduceMotion}
                  settled={landed}
                />
                {/* The money in transit: a copy of the From badge that
                    travels to the To badge, changing currency on the way. */}
                <span
                  aria-hidden="true"
                  className="pointer-events-none absolute z-10 grid h-7 w-7 place-items-center rounded-lg border border-emerald-500/70 bg-white font-medium text-sm text-zinc-900 opacity-0 shadow-sm dark:bg-zinc-900 dark:text-zinc-100"
                  ref={chipRef}
                >
                  <span className="col-start-1 row-start-1">
                    {symbolOf(from, locale)}
                  </span>
                  <span className="col-start-1 row-start-1 opacity-0">
                    {symbolOf(to, locale)}
                  </span>
                </span>
              </div>

              <div className="mt-2 flex items-center justify-center gap-2 text-xs text-zinc-500 tabular-nums dark:text-zinc-400">
                <span>
                  {processing ? "Live rate" : "Exchange Rate"}: 1{" "}
                  {from.currency} ={" "}
                  <RollingNumber value={formatNumber(liveRate, locale, 4)} />{" "}
                  {to.currency}
                </span>
                {/* Only once there is a rate to explain. The padding gives
                    the 12px icon a 24px target without moving the layout. */}
                {!processing && (
                  <Tooltip>
                    <TooltipTrigger
                      aria-label="Exchange rate details"
                      className="-m-1.5 rounded-sm p-1.5 focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-emerald-500/50"
                    >
                      <InfoIcon
                        aria-hidden="true"
                        className="h-3 w-3 text-zinc-400 transition-colors hover:text-zinc-600 dark:hover:text-zinc-300"
                      />
                    </TooltipTrigger>
                    <TooltipContent>
                      <p className="text-xs">Rate updated at {timestamp}</p>
                    </TooltipContent>
                  </Tooltip>
                )}
              </div>
            </div>
          </motion.div>
        </CardContent>
      </Card>
    </TooltipProvider>
  );
}
```

## Usage

With no props the card runs a demo: it shows "Transfer in Progress" and completes on its own. Pass `status` to drive it from your own transfer state.

```tsx
<CurrencyTransfer
  from={{ amount: 1200, currency: "GBP", symbol: "£", bank: "Monzo", last4: "1180" }}
  to={{ amount: 1404, currency: "USD", symbol: "$", bank: "Chase Bank", last4: "4589" }}
  rate={1.17}
  txnId="TXN-8F2K19QZ"
  timestamp="2:30 PM"
  status={isDone ? "completed" : "processing"}
/>
```

## Props

| Prop        | Type                                      | Default                            | Description                                               |
| ----------- | ----------------------------------------- | ---------------------------------- | --------------------------------------------------------- |
| `from`      | `TransferAccount`                         | 500.00 USD, Chase Bank ••••4589    | Sending account and amount.                               |
| `to`        | `TransferAccount`                         | 460.00 EUR, Deutsche Bank ••••7823 | Receiving account and amount.                             |
| `rate`      | `number`                                  | `0.92`                             | Units of `to.currency` per one `from.currency`.           |
| `txnId`     | `string`                                  | `"TXN-DAB3UL494"`                  | Transaction ID shown on completion.                       |
| `timestamp` | `string`                                  | `"10:45 AM"`                       | When the rate was set, shown in the info tooltip.         |
| `status`    | `"processing" \| "completed" \| "failed"` | —                                  | Controlled status. Omit it for the self-completing demo.  |
| `locale`    | `string`                                  | `"en-US"`                          | BCP 47 locale for amounts, currency symbols and the rate. |
| `className` | `string`                                  | —                                  | Extra classes for the card.                               |

`TransferAccount` is `{ amount: number; currency: string; symbol?: string; bank: string; last4?: string }`. Status changes are announced to screen readers, and with reduced motion the amounts and arc jump to their values and the chip and shake are skipped.


---

# Liquid Gauge
> A usage meter filled with liquid that sloshes, ripples and bubbles, built with React and a wave simulation.

Source: https://kokonutui.com/docs/cards/liquid-gauge

## Installation

```bash
npx shadcn@latest add @kokonutui/liquid-gauge
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Liquid Gauge
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// The surface is a row of columns joined by springs. Each column bobs
// around the fill line and pulls on its neighbours, so a push travels.
const COLUMNS = 28;
// Simulation, in px and seconds, on a fixed step.
const STEP = 1 / 120;
const SPREAD = 2600;
const RESTORE = 18;
const SURFACE_DAMPING = 2.2;
// The fill line follows the value on an underdamped spring, so a big change
// overshoots a little and settles, like a poured glass.
const LEVEL_STIFFNESS = 90;
const LEVEL_DAMPING = 11;
// How hard a sideways drag rocks the liquid, and how hard the pointer
// stirs it when moving through it.
const SLOSH = 4.5;
const STIR = 20;
const MAX_WAVE = 26;
// The meniscus: a lighter band riding just above the surface.
const RIM = 3;
// Bubbles rise while the level is climbing.
const BUBBLES = 10;
const BUBBLE_RATE = 0.06;
const REST_EPSILON = 0.02;

export interface LiquidGaugeProps {
  /** Controlled fill, 0 to 100. */
  value?: number;
  /** Initial fill when uncontrolled. */
  defaultValue?: number;
  onValueChange?: (value: number) => void;
  /** Turns the gauge into a read-only display. */
  readOnly?: boolean;
  label?: string;
  /** Capacity shown in the subline, in `unit`. */
  total?: number;
  unit?: string;
  /** From this fill on, the liquid turns red. */
  warnAt?: number;
  className?: string;
}

interface Bubble {
  x: number;
  y: number;
  r: number;
  speed: number;
  phase: number;
  alive: boolean;
}

const clamp = (v: number, min: number, max: number) =>
  Math.min(max, Math.max(min, v));

function haptic() {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(6);
  }
}

function surfacePolygon(
  heights: Float64Array,
  levelY: number,
  width: number,
  height: number,
  lift: number
) {
  let points = "";
  for (let i = 0; i < COLUMNS; i++) {
    const x = (i / (COLUMNS - 1)) * width;
    const y = clamp(levelY + heights[i] - lift, -40, height + 40);
    points += `${x.toFixed(1)}px ${y.toFixed(1)}px,`;
  }
  return `polygon(${points}${width}px ${height + 40}px,0px ${height + 40}px)`;
}

function flatPolygon(value: number, lift = 0) {
  const top = 100 - value;
  return `polygon(0% calc(${top}% - ${lift}px),100% calc(${top}% - ${lift}px),100% 100%,0% 100%)`;
}

function drawBubbles(
  bubbles: Bubble[],
  nodes: (HTMLSpanElement | null)[],
  time: number
) {
  bubbles.forEach((bubble, i) => {
    const node = nodes[i];
    if (!node) {
      return;
    }
    if (!bubble.alive) {
      node.style.opacity = "0";
      return;
    }
    const sway = Math.sin(time * 7 + bubble.phase) * 2.5;
    node.style.opacity = "1";
    node.style.transform = `translate3d(${(bubble.x + sway - bubble.r).toFixed(1)}px,${(bubble.y - bubble.r).toFixed(1)}px,0) scale(${(bubble.r / 4).toFixed(3)})`;
  });
}

function setText(nodes: (HTMLSpanElement | null)[], text: string) {
  for (const node of nodes) {
    if (node) {
      node.textContent = text;
    }
  }
}

function GaugeText({
  label,
  status,
  value,
  used,
  total,
  unit,
  percentRef,
  usedRef,
}: {
  label: string;
  status: string;
  value: number;
  used: string;
  total: number;
  unit: string;
  percentRef: (node: HTMLSpanElement | null) => void;
  usedRef: (node: HTMLSpanElement | null) => void;
}) {
  return (
    <>
      <div className="absolute inset-x-0 top-0 p-6">
        <p className="font-medium text-sm">{label}</p>
        <p className="mt-3 font-semibold text-6xl tabular-nums tracking-tight">
          <span ref={percentRef}>{Math.round(value)}</span>
          <span className="ml-0.5 font-medium text-3xl opacity-60">%</span>
        </p>
        <p className="mt-1 text-sm tabular-nums opacity-60">
          <span ref={usedRef}>{used}</span> of {total} {unit} used
        </p>
      </div>
      <p className="absolute bottom-6 left-6 font-medium text-sm">{status}</p>
      {/* Every ten percent, a short tick on the right wall. */}
      <div className="absolute inset-y-0 right-0 w-4">
        {[10, 20, 30, 40, 50, 60, 70, 80, 90].map((tick) => (
          <span
            className={cn(
              "absolute right-0 h-px bg-current opacity-30",
              tick === 50 ? "w-3" : "w-1.5"
            )}
            key={tick}
            style={{ top: `${100 - tick}%` }}
          />
        ))}
      </div>
    </>
  );
}

export default function LiquidGauge({
  value: valueProp,
  defaultValue = 72,
  onValueChange,
  readOnly = false,
  label = "Storage",
  total = 128,
  unit = "GB",
  warnAt = 90,
  className,
}: LiquidGaugeProps) {
  const [internal, setInternal] = useState(defaultValue);
  const value = clamp(valueProp ?? internal, 0, 100);
  const [dragging, setDragging] = useState(false);

  const rootRef = useRef<HTMLDivElement>(null);
  const liquidRef = useRef<HTMLDivElement>(null);
  const rimRef = useRef<HTMLDivElement>(null);
  const bubbleRefs = useRef<(HTMLSpanElement | null)[]>([]);
  const percentRefs = useRef<(HTMLSpanElement | null)[]>([]);
  const usedRefs = useRef<(HTMLSpanElement | null)[]>([]);

  const sim = useRef({
    heights: new Float64Array(COLUMNS),
    speeds: new Float64Array(COLUMNS),
    level: value,
    levelSpeed: 0,
    target: value,
    width: 0,
    height: 0,
    bubbles: Array.from(
      { length: BUBBLES },
      (): Bubble => ({ x: 0, y: 0, r: 0, speed: 0, phase: 0, alive: false })
    ),
    spawn: 0,
    shown: Math.round(value),
    raf: 0,
    last: 0,
    carry: 0,
    time: 0,
    pointerX: -1,
    pointerId: -1,
    visible: true,
    reduceMotion: false,
  });

  // Read inside the animation loop, which outlives the render it came from.
  const totalRef = useRef(total);
  totalRef.current = total;

  const setValue = useCallback(
    (next: number) => {
      const rounded = Math.round(clamp(next, 0, 100));
      if (valueProp === undefined) {
        setInternal(rounded);
      }
      onValueChange?.(rounded);
    },
    [valueProp, onValueChange]
  );

  const draw = useCallback(() => {
    const s = sim.current;
    const { width, height } = s;
    if (!(width && height)) {
      return;
    }
    const levelY = height * (1 - s.level / 100);
    if (liquidRef.current) {
      liquidRef.current.style.clipPath = surfacePolygon(
        s.heights,
        levelY,
        width,
        height,
        0
      );
    }
    if (rimRef.current) {
      rimRef.current.style.clipPath = surfacePolygon(
        s.heights,
        levelY,
        width,
        height,
        RIM
      );
    }
    drawBubbles(s.bubbles, bubbleRefs.current, s.time);
    const shown = Math.round(clamp(s.level, 0, 100));
    if (shown !== s.shown) {
      s.shown = shown;
      const used = ((shown / 100) * totalRef.current).toFixed(1);
      setText(percentRefs.current, String(shown));
      setText(usedRefs.current, used);
    }
  }, []);

  const spawnBubbles = useCallback((dt: number) => {
    const s = sim.current;
    // Only a climbing level makes bubbles, more the faster it climbs.
    s.spawn += Math.max(0, s.levelSpeed) * BUBBLE_RATE * dt;
    while (s.spawn >= 1) {
      s.spawn -= 1;
      const free = s.bubbles.find((b) => !b.alive);
      if (!free) {
        s.spawn = 0;
        break;
      }
      free.alive = true;
      free.x = s.width * (0.12 + Math.random() * 0.76);
      free.y = s.height - 6;
      free.r = 1.5 + Math.random() * 2.5;
      free.speed = 70 + Math.random() * 80;
      free.phase = Math.random() * Math.PI * 2;
    }
  }, []);

  const advanceBubbles = useCallback((dt: number) => {
    const s = sim.current;
    const levelY = s.height * (1 - s.level / 100);
    const column = (x: number) =>
      clamp(Math.round((x / s.width) * (COLUMNS - 1)), 0, COLUMNS - 1);
    let alive = 0;
    for (const bubble of s.bubbles) {
      if (!bubble.alive) {
        continue;
      }
      bubble.y -= bubble.speed * dt;
      const i = column(bubble.x);
      // At the surface it pops, and leaves a tiny dimple behind.
      if (bubble.y - bubble.r <= levelY + s.heights[i]) {
        bubble.alive = false;
        s.speeds[i] += bubble.r * 6;
      } else {
        alive++;
      }
    }
    return alive;
  }, []);

  const step = useCallback(() => {
    const s = sim.current;
    const { heights, speeds } = s;
    // Fill line spring.
    const force =
      (s.target - s.level) * LEVEL_STIFFNESS - s.levelSpeed * LEVEL_DAMPING;
    s.levelSpeed += force * STEP;
    s.level += s.levelSpeed * STEP;
    // Surface springs, with walls that reflect.
    let energy = Math.abs(s.target - s.level) + Math.abs(s.levelSpeed) * 0.1;
    for (let i = 0; i < COLUMNS; i++) {
      const left = heights[i > 0 ? i - 1 : i];
      const right = heights[i < COLUMNS - 1 ? i + 1 : i];
      const accel =
        (left + right - 2 * heights[i]) * SPREAD -
        heights[i] * RESTORE -
        speeds[i] * SURFACE_DAMPING;
      speeds[i] += accel * STEP;
    }
    for (let i = 0; i < COLUMNS; i++) {
      heights[i] = clamp(heights[i] + speeds[i] * STEP, -MAX_WAVE, MAX_WAVE);
      energy = Math.max(
        energy,
        Math.abs(heights[i]),
        Math.abs(speeds[i]) * 0.1
      );
    }
    s.time += STEP;
    return energy;
  }, []);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      s.carry += elapsed;
      let energy = 0;
      while (s.carry >= STEP) {
        energy = Math.max(energy, step());
        s.carry -= STEP;
      }
      spawnBubbles(elapsed);
      const bubbles = advanceBubbles(elapsed);
      draw();
      const busy = s.pointerId >= 0 || bubbles > 0 || energy > REST_EPSILON;
      if (busy && s.visible) {
        s.raf = requestAnimationFrame(tick);
      } else {
        s.last = 0;
        if (!busy) {
          // Settle exactly, so the resting surface is flat.
          s.level = s.target;
          s.levelSpeed = 0;
          s.heights.fill(0);
          s.speeds.fill(0);
          draw();
        }
      }
    },
    [advanceBubbles, draw, spawnBubbles, step]
  );

  const wake = useCallback(() => {
    const s = sim.current;
    if (!s.raf && s.visible) {
      s.raf = requestAnimationFrame(tick);
    }
  }, [tick]);

  // A new value: the spring takes it from here.
  useEffect(() => {
    const s = sim.current;
    if (s.target === value) {
      return;
    }
    s.target = value;
    if (s.reduceMotion) {
      s.level = value;
      s.levelSpeed = 0;
      draw();
      return;
    }
    wake();
  }, [value, draw, wake]);

  useEffect(() => {
    const s = sim.current;
    const root = rootRef.current;
    if (!root) {
      return;
    }
    const motion = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = motion.matches;
    const onMotion = () => {
      s.reduceMotion = motion.matches;
    };
    motion.addEventListener("change", onMotion);

    const resize = new ResizeObserver(([entry]) => {
      s.width = entry.contentRect.width;
      s.height = entry.contentRect.height;
      draw();
    });
    resize.observe(root);

    // Offscreen or in a background tab, the loop waits.
    const pause = () => {
      if (!s.visible && s.raf) {
        cancelAnimationFrame(s.raf);
        s.raf = 0;
        s.last = 0;
      } else if (s.visible) {
        wake();
      }
    };
    let onScreen = true;
    const intersection = new IntersectionObserver(([entry]) => {
      onScreen = entry.isIntersecting;
      s.visible = onScreen && !document.hidden;
      pause();
    });
    intersection.observe(root);
    const onVisibility = () => {
      s.visible = onScreen && !document.hidden;
      pause();
    };
    document.addEventListener("visibilitychange", onVisibility);

    return () => {
      motion.removeEventListener("change", onMotion);
      resize.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, [draw, wake]);

  const valueAt = (clientY: number) => {
    const rect = rootRef.current?.getBoundingClientRect();
    if (!rect) {
      return value;
    }
    return (1 - (clientY - rect.top) / rect.height) * 100;
  };

  // Push the columns around x by `amount`, fading out over a few columns.
  const disturb = (clientX: number, amount: number, reach = 3) => {
    const s = sim.current;
    const rect = rootRef.current?.getBoundingClientRect();
    if (!rect || s.reduceMotion) {
      return;
    }
    const center = ((clientX - rect.left) / rect.width) * (COLUMNS - 1);
    for (let i = 0; i < COLUMNS; i++) {
      const falloff = 1 - Math.abs(i - center) / reach;
      if (falloff > 0) {
        s.speeds[i] += amount * falloff;
      }
    }
  };

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    if (readOnly || (event.pointerType === "mouse" && event.button !== 0)) {
      return;
    }
    const s = sim.current;
    event.currentTarget.setPointerCapture(event.pointerId);
    s.pointerId = event.pointerId;
    s.pointerX = event.clientX;
    setDragging(true);
    // The press itself lands like a drop.
    disturb(event.clientX, 260, 2.5);
    setValue(valueAt(event.clientY));
    wake();
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    const dx = s.pointerX < 0 ? 0 : event.clientX - s.pointerX;
    s.pointerX = event.clientX;
    if (s.reduceMotion) {
      if (s.pointerId === event.pointerId) {
        setValue(valueAt(event.clientY));
      }
      return;
    }
    if (s.pointerId === event.pointerId) {
      // A sideways drag rocks the whole body: one side rises, the other
      // falls, and the springs carry it back and forth.
      for (let i = 0; i < COLUMNS; i++) {
        s.speeds[i] += ((i / (COLUMNS - 1)) * 2 - 1) * dx * SLOSH;
      }
      setValue(valueAt(event.clientY));
      wake();
      return;
    }
    // Hovering through the liquid stirs it, behind the cursor.
    const rect = rootRef.current?.getBoundingClientRect();
    if (event.pointerType !== "mouse" || !rect || dx === 0) {
      return;
    }
    const levelY = rect.height * (1 - s.level / 100);
    if (event.clientY - rect.top > levelY + 8) {
      disturb(event.clientX, Math.abs(dx) * STIR, 2);
      wake();
    }
  };

  const handlePointerUp = (event: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    if (s.pointerId !== event.pointerId) {
      return;
    }
    s.pointerId = -1;
    setDragging(false);
    haptic();
    wake();
  };

  const handlePointerLeave = () => {
    if (sim.current.pointerId < 0) {
      sim.current.pointerX = -1;
    }
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    if (readOnly) {
      return;
    }
    const steps: Record<string, number> = {
      ArrowUp: 1,
      ArrowRight: 1,
      ArrowDown: -1,
      ArrowLeft: -1,
      PageUp: 10,
      PageDown: -10,
    };
    let next: number | undefined;
    if (event.key in steps) {
      next = value + steps[event.key] * (event.shiftKey ? 10 : 1);
    } else if (event.key === "Home") {
      next = 0;
    } else if (event.key === "End") {
      next = 100;
    }
    if (next === undefined) {
      return;
    }
    event.preventDefault();
    // A keyed change still lands with a small ripple.
    const rect = rootRef.current?.getBoundingClientRect();
    if (rect) {
      disturb(rect.left + rect.width / 2, next > value ? 120 : -120, 4);
    }
    setValue(next);
    wake();
  };

  const warn = value >= warnAt;
  const status = warn ? "Almost full" : `${100 - Math.round(value)}% free`;
  const used = ((Math.round(value) / 100) * total).toFixed(1);
  const textProps = {
    label,
    status,
    value,
    used,
    total,
    unit,
  };

  return (
    <div
      aria-label={label}
      aria-readonly={readOnly || undefined}
      aria-valuemax={100}
      aria-valuemin={0}
      aria-valuenow={Math.round(value)}
      aria-valuetext={`${Math.round(value)}%, ${used} of ${total} ${unit} used`}
      className={cn(
        "relative h-[22.5rem] w-72 touch-none select-none overflow-hidden rounded-3xl border border-zinc-200 bg-white text-zinc-900 outline-none dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        "focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 dark:focus-visible:ring-offset-zinc-950",
        !readOnly && (dragging ? "cursor-grabbing" : "cursor-ns-resize"),
        className
      )}
      onKeyDown={handleKeyDown}
      onLostPointerCapture={handlePointerUp}
      onPointerCancel={handlePointerUp}
      onPointerDown={handlePointerDown}
      onPointerLeave={handlePointerLeave}
      onPointerMove={handlePointerMove}
      onPointerUp={handlePointerUp}
      ref={rootRef}
      role="slider"
      tabIndex={readOnly ? -1 : 0}
    >
      <GaugeText
        {...textProps}
        percentRef={(node) => {
          percentRefs.current[0] = node;
        }}
        usedRef={(node) => {
          usedRefs.current[0] = node;
        }}
      />

      {/* The meniscus, a lighter band just above the liquid. */}
      <div
        aria-hidden="true"
        className={cn(
          "pointer-events-none absolute inset-0 transition-colors duration-300 ease-out",
          warn ? "bg-red-300 dark:bg-red-900" : "bg-zinc-300 dark:bg-zinc-600"
        )}
        ref={rimRef}
        style={{ clipPath: flatPolygon(value, RIM) }}
      />

      {/* The liquid, with a second copy of the text in its own colour. */}
      <div
        aria-hidden="true"
        className={cn(
          "pointer-events-none absolute inset-0 transition-colors duration-300 ease-out",
          warn
            ? "bg-red-500 text-white"
            : "bg-zinc-900 text-white dark:bg-zinc-100 dark:text-zinc-900"
        )}
        ref={liquidRef}
        style={{ clipPath: flatPolygon(value) }}
      >
        <GaugeText
          {...textProps}
          percentRef={(node) => {
            percentRefs.current[1] = node;
          }}
          usedRef={(node) => {
            usedRefs.current[1] = node;
          }}
        />
        {Array.from({ length: BUBBLES }, (_, i) => (
          <span
            className="absolute top-0 left-0 size-2 rounded-full border border-current bg-current/20 opacity-0"
            key={`bubble-${i.toString()}`}
            ref={(node) => {
              bubbleRefs.current[i] = node;
            }}
          />
        ))}
      </div>
    </div>
  );
}
```


---

# Now Playing
> Music card with a spinning disc you can grab and turn to scrub, built with React and Tailwind CSS.

Source: https://kokonutui.com/docs/cards/liquid-glass-card

## Installation

```bash
npx shadcn@latest add @kokonutui/liquid-glass-card
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Now Playing - music card with a spinning, scrubbable disc
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { cva, type VariantProps } from "class-variance-authority";
import { Pause, Play, SkipBack, SkipForward } from "lucide-react";
import React from "react";
import { Button } from "@/components/ui/button";
import { Card } from "@/components/ui/card";
import { cn } from "@/lib/utils";

/* -------------------------------------------------------------------------- */
/*  Glass primitives, kept for existing installs; the glass is now opt-in.    */
/* -------------------------------------------------------------------------- */

const GLASS_SHADOW_LIGHT =
  "shadow-[0_0_6px_rgba(0,0,0,0.03),0_2px_6px_rgba(0,0,0,0.08),inset_3px_3px_0.5px_-3px_rgba(0,0,0,0.9),inset_-3px_-3px_0.5px_-3px_rgba(0,0,0,0.85),inset_1px_1px_1px_-0.5px_rgba(0,0,0,0.6),inset_-1px_-1px_1px_-0.5px_rgba(0,0,0,0.6),inset_0_0_6px_6px_rgba(0,0,0,0.12),inset_0_0_2px_2px_rgba(0,0,0,0.06),0_0_12px_rgba(255,255,255,0.15)]";

const GLASS_SHADOW_DARK =
  "dark:shadow-[0_0_8px_rgba(0,0,0,0.03),0_2px_6px_rgba(0,0,0,0.08),inset_3px_3px_0.5px_-3.5px_rgba(255,255,255,0.09),inset_-3px_-3px_0.5px_-3.5px_rgba(255,255,255,0.85),inset_1px_1px_1px_-0.5px_rgba(255,255,255,0.6),inset_-1px_-1px_1px_-0.5px_rgba(255,255,255,0.6),inset_0_0_6px_6px_rgba(255,255,255,0.12),inset_0_0_2px_2px_rgba(255,255,255,0.06),0_0_12px_rgba(0,0,0,0.15)]";

const GLASS_SHADOW = `${GLASS_SHADOW_LIGHT} ${GLASS_SHADOW_DARK}`;

const DEFAULT_GLASS_FILTER_SCALE = 30;
const BUTTON_GLASS_FILTER_SCALE = 70;

interface GlassFilterProps {
  id: string;
  scale?: number;
}

const GlassFilter = React.memo(
  ({ id, scale = DEFAULT_GLASS_FILTER_SCALE }: GlassFilterProps) => (
    <svg aria-hidden="true" className="hidden" focusable={false}>
      <defs>
        <filter
          colorInterpolationFilters="sRGB"
          height="200%"
          id={id}
          width="200%"
          x="-50%"
          y="-50%"
        >
          <feTurbulence
            baseFrequency="0.05 0.05"
            numOctaves="1"
            result="turbulence"
            seed="1"
            type="fractalNoise"
          />
          <feGaussianBlur
            in="turbulence"
            result="blurredNoise"
            stdDeviation="2"
          />
          <feDisplacementMap
            in="SourceGraphic"
            in2="blurredNoise"
            result="displaced"
            scale={scale}
            xChannelSelector="R"
            yChannelSelector="B"
          />
          <feGaussianBlur in="displaced" stdDeviation="4" />
        </filter>
      </defs>
    </svg>
  )
);
GlassFilter.displayName = "GlassFilter";

// Press feedback is colour only: no hover or press scale.
const liquidButtonVariants = cva(
  "relative transition-colors duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none",
  {
    variants: {
      liquidVariant: {
        default: "",
        none: "",
      },
    },
    defaultVariants: {
      liquidVariant: "default",
    },
  }
);

// No `asChild`: the glass layers are extra children, which Slot rejects.
export type LiquidButtonProps = Omit<
  React.ComponentProps<typeof Button>,
  "asChild"
> &
  VariantProps<typeof liquidButtonVariants> & {
    /** Adds the inset glass shadow and SVG refraction (Chromium only). */
    glassEffect?: boolean;
  };

function LiquidButton({
  className,
  liquidVariant = "default",
  glassEffect = false,
  children,
  ...props
}: LiquidButtonProps) {
  const filterId = React.useId();

  return (
    <>
      <Button
        className={cn(liquidButtonVariants({ liquidVariant }), className)}
        {...props}
      >
        {glassEffect && (
          <>
            <span
              className={cn(
                "pointer-events-none absolute inset-0 rounded-[inherit]",
                GLASS_SHADOW
              )}
            />
            {/* backdrop-filter: url() only renders in Chromium. */}
            <span
              className="pointer-events-none absolute inset-0 isolate -z-10 overflow-hidden rounded-[inherit]"
              style={{ backdropFilter: `url("#${filterId}")` }}
            />
          </>
        )}
        <span className="relative z-10 inline-flex items-center justify-center">
          {children}
        </span>
      </Button>
      {glassEffect && (
        <GlassFilter id={filterId} scale={BUTTON_GLASS_FILTER_SCALE} />
      )}
    </>
  );
}

const liquidGlassCardVariants = cva("relative overflow-hidden", {
  variants: {
    glassSize: {
      sm: "p-4",
      default: "p-6",
      lg: "p-8",
    },
  },
  defaultVariants: {
    glassSize: "default",
  },
});

export type LiquidGlassCardProps = React.HTMLAttributes<HTMLDivElement> &
  VariantProps<typeof liquidGlassCardVariants> & {
    /** Adds the inset glass shadow and SVG refraction (Chromium only). */
    glassEffect?: boolean;
  };

function LiquidGlassCard({
  className,
  glassSize,
  glassEffect = false,
  children,
  ...props
}: LiquidGlassCardProps) {
  const filterId = React.useId();

  return (
    <Card
      className={cn(
        liquidGlassCardVariants({ glassSize }),
        glassEffect && "bg-white/40 backdrop-blur-[2px] dark:bg-zinc-950/40",
        className
      )}
      {...props}
    >
      {glassEffect && (
        <>
          <div
            className={cn(
              "pointer-events-none absolute inset-0 rounded-[inherit]",
              GLASS_SHADOW
            )}
          />
          {/* backdrop-filter: url() only renders in Chromium. */}
          <div
            className="pointer-events-none absolute inset-0 -z-10 overflow-hidden rounded-[inherit]"
            style={{ backdropFilter: `url("#${filterId}")` }}
          />
          <GlassFilter id={filterId} scale={DEFAULT_GLASS_FILTER_SCALE} />
        </>
      )}
      <div className="relative z-10">{children}</div>
    </Card>
  );
}

/* -------------------------------------------------------------------------- */
/*  Now Playing                                                               */
/* -------------------------------------------------------------------------- */

export interface NowPlayingTrack {
  title: string;
  artist: string;
  /** Length in seconds. */
  duration: number;
  /** Which built-in label design is printed on the disc (0, 1 or 2). */
  artwork?: number;
}

const DEFAULT_TRACKS: NowPlayingTrack[] = [
  { title: "Low Tide", artist: "Pale Harbor", duration: 192, artwork: 0 },
  { title: "Static Bloom", artist: "Juniper Wire", duration: 167, artwork: 1 },
  {
    title: "Night Signal",
    artist: "The Quiet Hours",
    duration: 245,
    artwork: 2,
  },
];

// 33⅓ rpm is 200°/s, one turn every 1.8s.
const CRUISE = 200;
const CRUISE_MS = 1800;
// Fastest a flick may spin the disc (6 turns/s).
const MAX_OMEGA = 2160;
// Time constants (s) for the speed relaxing toward its target: back to
// cruise after a flick, up to speed on play, down to a stop on pause.
const COAST_TAU = 0.45;
const SPIN_UP_TAU = 0.22;
const SPIN_DOWN_TAU = 0.2;
const SETTLE_EPSILON = 2;
// Pointer movement this close to the centre gives wild angle jumps.
const DEAD_ZONE = 10;
const VELOCITY_WINDOW_MS = 80;
// A release this long after the last move is a release from rest.
const STALE_MOVE_MS = 60;
// A finger resting on the disc reads as zero speed within ~50ms.
const HOLD_SETTLE_S = 0.05;
// Level bars: resting height, the fall to rest on pause, and the attack.
const BAR_COUNT = 5;
const BAR_REST = 0.14;
const BAR_DECAY_S = 0.3;
const BAR_ATTACK_S = 0.08;
// Scrubber: how far (px) the rail may stretch past either end.
const RUBBER_MAX = 18;
const SEEK_STEP = 5;
const RESTART_THRESHOLD = 3;
const MAX_DT = 0.05;
const ROLL_MS = 220;
const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";
const RUBBER_RETURN = "transform 450ms cubic-bezier(0.34, 1.4, 0.64, 1)";

// Shipped with the component so it needs nothing in globals.css.
const ROLL_KEYFRAMES = `@keyframes now-playing-in-up{from{transform:translateY(90%);opacity:0}to{transform:none;opacity:1}}
@keyframes now-playing-out-up{from{transform:none;opacity:1}to{transform:translateY(-90%);opacity:0}}
@keyframes now-playing-in-down{from{transform:translateY(-90%);opacity:0}to{transform:none;opacity:1}}
@keyframes now-playing-out-down{from{transform:none;opacity:1}to{transform:translateY(90%);opacity:0}}
@media (prefers-reduced-motion:reduce){.now-playing-roll{animation:none!important}.now-playing-roll-prev{display:none}}`;

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), max);
}

function damp(distance: number, max: number) {
  return max * (1 - Math.exp(-distance / max));
}

function formatTime(seconds: number) {
  const s = Math.max(0, Math.floor(seconds));
  return `${Math.floor(s / 60)}:${(s % 60).toString().padStart(2, "0")}`;
}

// Deterministic 1D value noise. The meter is a function of track time, so
// scrubbing back over a passage replays the same levels.
function hash(n: number) {
  const s = Math.sin(n * 127.1) * 43_758.5453;
  return s - Math.floor(s);
}

function noise(x: number) {
  const i = Math.floor(x);
  const f = x - i;
  const u = f * f * (3 - 2 * f);
  return hash(i) * (1 - u) + hash(i + 1) * u;
}

function barLevel(index: number, t: number) {
  return (
    0.6 * noise(t * 4.3 + index * 17.3) +
    0.4 * noise(t * 9.1 + index * 31.7 + 100)
  );
}

// Up to cruise speed the disc maps 1:1 to the track like a real record;
// faster spins accelerate, so a hard flick can cross most of a song.
function scrubGain(speed: number) {
  const excess = Math.max(0, Math.abs(speed) - CRUISE) / CRUISE;
  return 1 + 1.5 * excess ** 1.5;
}

/** Seconds of track per second, at a disc speed in deg/s. */
function trackRate(omega: number) {
  return (omega / CRUISE) * scrubGain(omega);
}

function rotate(angle: number) {
  return `rotate(${Math.round((angle % 360) * 100) / 100}deg)`;
}

interface Engine {
  angle: number;
  omega: number;
  time: number;
  duration: number;
  playing: boolean;
  held: boolean;
  barDrag: boolean;
  /** The one pointer driving the disc or the bar; others are ignored. */
  pointerId: number | null;
  visible: boolean;
  reduced: boolean;
  /** Meter envelope, 0 (rest) to 1 (full). */
  env: number;
  /** Disc speed measured from the pointer while held (deg/s). */
  scrubOmega: number;
  pointerAngle: number;
  center: { x: number; y: number };
  lastMoveAt: number;
  samples: { t: number; a: number }[];
  cruise: Animation | null;
  cruiseAngle: number;
}

function createEngine(duration: number, playing: boolean): Engine {
  return {
    angle: 0,
    omega: playing ? CRUISE : 0,
    time: 0,
    duration,
    playing,
    held: false,
    barDrag: false,
    pointerId: null,
    visible: true,
    reduced: false,
    env: 0,
    scrubOmega: 0,
    pointerAngle: 0,
    center: { x: 0, y: 0 },
    lastMoveAt: 0,
    samples: [],
    cruise: null,
    cruiseAngle: 0,
  };
}

function readAngle(e: Engine) {
  if (e.cruise && e.cruise.currentTime !== null) {
    return e.cruiseAngle + (Number(e.cruise.currentTime) / CRUISE_MS) * 360;
  }
  return e.angle;
}

function stopCruise(e: Engine, disc: HTMLElement | null) {
  if (!e.cruise) {
    return;
  }
  e.angle = readAngle(e);
  // Pin the angle inline before cancelling so the disc doesn't flash back.
  if (disc) {
    disc.style.transform = rotate(e.angle);
  }
  e.cruise.cancel();
  e.cruise = null;
}

// Steady 33⅓ runs as a WAAPI animation on the compositor, so the disc keeps
// turning smoothly even when the main thread is busy.
function startCruise(e: Engine, disc: HTMLElement | null) {
  if (e.cruise || e.reduced || !disc || typeof disc.animate !== "function") {
    return;
  }
  e.angle %= 360;
  e.cruiseAngle = e.angle;
  e.cruise = disc.animate(
    [
      { transform: `rotate(${e.angle}deg)` },
      { transform: `rotate(${e.angle + 360}deg)` },
    ],
    { duration: CRUISE_MS, iterations: Number.POSITIVE_INFINITY }
  );
  if (!e.visible) {
    e.cruise.pause();
  }
}

// Free disc: the speed relaxes toward cruise (playing) or zero (paused) and
// the track follows however far the disc turned.
function integrateDisc(e: Engine, dt: number, disc: HTMLElement | null) {
  const target = e.playing ? CRUISE : 0;
  if (e.reduced) {
    e.omega = target;
    e.time += e.playing ? dt : 0;
    return;
  }
  if (e.cruise) {
    e.omega = CRUISE;
    e.time += dt;
    return;
  }
  let tau = SPIN_UP_TAU;
  if (Math.abs(e.omega) > Math.abs(target)) {
    tau = e.playing ? COAST_TAU : SPIN_DOWN_TAU;
  }
  e.omega = target + (e.omega - target) * Math.exp(-dt / tau);
  if (Math.abs(e.omega - target) < SETTLE_EPSILON) {
    e.omega = target;
  }
  e.angle += e.omega * dt;
  e.time += trackRate(e.omega) * dt;
  if (e.playing && e.omega === CRUISE) {
    startCruise(e, disc);
  }
}

function meterTarget(e: Engine) {
  if (e.held) {
    return clamp(Math.abs(e.scrubOmega) / CRUISE, 0, 1);
  }
  return clamp(Math.abs(e.omega) / CRUISE, 0, 1);
}

function updateMeter(e: Engine, dt: number, bars: (HTMLElement | null)[]) {
  const target = meterTarget(e);
  if (e.reduced) {
    e.env = e.playing ? 1 : 0;
  } else if (target > e.env) {
    e.env = Math.min(target, e.env + dt / BAR_ATTACK_S);
  } else {
    // A linear fall: a full meter takes 300ms to come to rest.
    e.env = Math.max(target, e.env - dt / BAR_DECAY_S);
  }
  // Reduced motion shows one still frame of the meter.
  const t = e.reduced ? 0.37 : e.time;
  for (const [i, bar] of bars.entries()) {
    if (bar) {
      const level = BAR_REST + (1 - BAR_REST) * barLevel(i, t) * e.env;
      bar.style.transform = `scaleY(${level.toFixed(3)})`;
    }
  }
}

function rpmLabel(e: Engine) {
  if (e.held) {
    return `${Math.round(e.scrubOmega / 6)} rpm`;
  }
  if (e.omega === CRUISE) {
    return "33⅓ rpm";
  }
  return `${Math.round(e.omega / 6)} rpm`;
}

function paint(
  e: Engine,
  disc: HTMLElement | null,
  fill: HTMLElement | null,
  rpm: HTMLElement | null
) {
  if (disc && !e.cruise) {
    disc.style.transform = rotate(e.angle);
  }
  if (fill) {
    const p = e.duration > 0 ? clamp(e.time / e.duration, 0, 1) : 0;
    fill.style.transform = `scaleX(${p.toFixed(4)})`;
  }
  const label = rpmLabel(e);
  if (rpm && rpm.textContent !== label) {
    rpm.textContent = label;
  }
}

/* ------------------------------ Rolling time ------------------------------ */

interface RollDigitProps {
  value: string;
  direction: 1 | -1;
}

function RollDigit({ value, direction }: RollDigitProps) {
  const [state, setState] = React.useState<{
    current: string;
    previous: string | null;
    count: number;
    direction: 1 | -1;
  }>({ current: value, previous: null, count: 0, direction });

  // Derived during render: the old digit rolls out as the new one rolls in.
  if (state.current !== value) {
    setState({
      current: value,
      previous: state.current,
      count: state.count + 1,
      direction,
    });
  }

  const up = state.direction > 0;
  const timing = `${ROLL_MS}ms ${EASE_OUT} both`;

  return (
    <span className="relative inline-block h-[1lh] overflow-hidden">
      {state.previous !== null && (
        <span
          className="now-playing-roll now-playing-roll-prev absolute inset-0"
          key={`p${state.count}`}
          style={{
            animation: `${up ? "now-playing-out-up" : "now-playing-out-down"} ${timing}`,
          }}
        >
          {state.previous}
        </span>
      )}
      <span
        className="now-playing-roll block"
        key={`c${state.count}`}
        style={
          state.count > 0
            ? {
                animation: `${up ? "now-playing-in-up" : "now-playing-in-down"} ${timing}`,
              }
            : undefined
        }
      >
        {state.current}
      </span>
    </span>
  );
}

interface RollingTimeProps {
  seconds: number;
  direction: 1 | -1;
}

function RollingTime({ seconds, direction }: RollingTimeProps) {
  // Slots are counted from the right so the seconds keep their identity
  // when the minutes gain a digit.
  const chars = formatTime(seconds).split("").reverse();
  return (
    <span aria-hidden="true" className="inline-flex flex-row-reverse">
      {chars.map((char, slot) =>
        char === ":" ? (
          <span key="colon">:</span>
        ) : (
          <RollDigit
            direction={direction}
            // biome-ignore lint/suspicious/noArrayIndexKey: digit slots are positional
            key={`slot-${slot}`}
            value={char}
          />
        )
      )}
    </span>
  );
}

/* --------------------------------- Artwork -------------------------------- */

const INK = "fill-zinc-900";
const ACCENT = "fill-(--now-playing-accent)";

const DOT_GRID = Array.from({ length: 25 }, (_, i) => ({
  x: 26 + (i % 5) * 12,
  y: 26 + Math.floor(i / 5) * 12,
  lit: i === 8,
}));

// Printed labels: flat zinc plus the accent, deliberately lopsided so the
// rotation reads at a glance.
function LabelArt({ variant }: { variant: number }) {
  if (variant === 1) {
    return (
      <g>
        <path className={ACCENT} d="M50 50 L50 8 A42 42 0 0 1 92 50 Z" />
        <path className={INK} d="M50 50 L8 50 A42 42 0 0 1 50 8 Z" />
        <rect className={INK} height="6" rx="1" width="30" x="50" y="62" />
        <rect className={INK} height="6" rx="1" width="20" x="50" y="72" />
      </g>
    );
  }
  if (variant === 2) {
    return (
      <g>
        {DOT_GRID.map((dot) => (
          <circle
            className={dot.lit ? ACCENT : INK}
            cx={dot.x}
            cy={dot.y}
            key={`${dot.x}-${dot.y}`}
            r={dot.lit ? 5.5 : 2.6}
          />
        ))}
      </g>
    );
  }
  return (
    <g>
      <circle className={ACCENT} cx="64" cy="36" r="20" />
      <rect className={INK} height="5" width="64" x="18" y="60" />
      <rect className={INK} height="5" width="52" x="18" y="70" />
      <rect className={INK} height="5" width="40" x="18" y="80" />
    </g>
  );
}

const GROOVES = [28, 31, 34, 37, 40, 43, 46];

function Disc({ artwork }: { artwork: number }) {
  const clipId = React.useId();
  return (
    <svg aria-hidden="true" className="size-full" viewBox="0 0 100 100">
      <circle
        className="fill-zinc-900 dark:fill-black"
        cx="50"
        cy="50"
        r="50"
      />
      {GROOVES.map((r) => (
        <circle
          className="fill-none stroke-white/[0.08]"
          cx="50"
          cy="50"
          key={r}
          r={r}
          strokeWidth="0.6"
        />
      ))}
      <circle
        className="fill-none stroke-white/[0.16]"
        cx="50"
        cy="50"
        r="49"
        strokeWidth="0.8"
      />
      <clipPath id={clipId}>
        <circle cx="50" cy="50" r="24" />
      </clipPath>
      <circle className="fill-zinc-100" cx="50" cy="50" r="24" />
      <g clipPath={`url(#${clipId})`} transform="translate(26 26) scale(0.48)">
        <LabelArt variant={artwork} />
      </g>
      <circle
        className="fill-white dark:fill-zinc-900"
        cx="50"
        cy="50"
        r="1.8"
      />
    </svg>
  );
}

function Tonearm({ down }: { down: boolean }) {
  return (
    <svg
      aria-hidden="true"
      className="pointer-events-none absolute -top-1 -right-4 h-[80%] w-auto origin-[77.5%_10%] transition-transform duration-500 ease-[cubic-bezier(0.77,0,0.175,1)] motion-reduce:transition-none"
      style={{ transform: down ? "rotate(11deg)" : "rotate(-8deg)" }}
      viewBox="0 0 40 110"
    >
      <circle
        className="fill-zinc-200 stroke-zinc-300 dark:fill-zinc-700 dark:stroke-zinc-600"
        cx="31"
        cy="11"
        r="8"
      />
      <circle className="fill-zinc-400" cx="31" cy="11" r="3" />
      <path
        className="fill-none stroke-zinc-400 dark:stroke-zinc-500"
        d="M31 11 L31 70 L18 92"
        strokeLinecap="round"
        strokeLinejoin="round"
        strokeWidth="2.5"
      />
      <rect
        className="fill-zinc-600 dark:fill-zinc-300"
        height="12"
        rx="1.5"
        transform="rotate(32 16 96)"
        width="7"
        x="12.5"
        y="90"
      />
    </svg>
  );
}

/* ------------------------------- Now Playing ------------------------------ */

export interface NowPlayingProps {
  tracks?: NowPlayingTrack[];
  /** Index of the track loaded first. */
  defaultTrack?: number;
  /** Start playing on mount. */
  autoPlay?: boolean;
  /** The one accent colour: meter, progress and label art. */
  accent?: string;
  /** Wraps the card in the glass shadow and SVG refraction (Chromium only). */
  glassEffect?: boolean;
  onTrackChange?: (index: number) => void;
  className?: string;
}

const ICON_BUTTON =
  "inline-flex size-10 items-center justify-center rounded-full text-zinc-600 transition-colors duration-150 hover:bg-zinc-100 hover:text-zinc-900 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 active:bg-zinc-200 dark:text-zinc-400 dark:active:bg-zinc-700 dark:hover:bg-zinc-800 dark:hover:text-zinc-100";

const FRAME =
  "@container/now-playing w-full max-w-sm rounded-3xl border border-zinc-200 p-5 shadow-sm dark:border-zinc-800";

export function NowPlaying({
  tracks = DEFAULT_TRACKS,
  defaultTrack = 0,
  autoPlay = true,
  accent = "#f97316",
  glassEffect = false,
  onTrackChange,
  className,
}: NowPlayingProps) {
  const list = tracks.length > 0 ? tracks : DEFAULT_TRACKS;
  const [trackIndex, setTrackIndex] = React.useState(() =>
    clamp(defaultTrack, 0, list.length - 1)
  );
  const track = list[trackIndex] ?? DEFAULT_TRACKS[0];
  const [playing, setPlaying] = React.useState(autoPlay);
  const [clock, setClock] = React.useState<{ s: number; dir: 1 | -1 }>({
    s: 0,
    dir: 1,
  });

  const engineRef = React.useRef<Engine | null>(null);
  if (engineRef.current === null) {
    engineRef.current = createEngine(track.duration, autoPlay);
  }
  const rootRef = React.useRef<HTMLDivElement>(null);
  const discRef = React.useRef<HTMLDivElement>(null);
  const fillRef = React.useRef<HTMLDivElement>(null);
  const railRef = React.useRef<HTMLDivElement>(null);
  const rpmRef = React.useRef<HTMLSpanElement>(null);
  const barRefs = React.useRef<(HTMLSpanElement | null)[]>([]);
  const wakeRef = React.useRef<() => void>(() => undefined);
  const clockRef = React.useRef(0);

  // Read through refs so the loop is set up once and never restarted.
  const listRef = React.useRef(list);
  listRef.current = list;
  const trackIndexRef = React.useRef(trackIndex);
  trackIndexRef.current = trackIndex;
  const onTrackChangeRef = React.useRef(onTrackChange);
  onTrackChangeRef.current = onTrackChange;

  const loadTrack = React.useCallback((index: number) => {
    const all = listRef.current;
    const nextIndex = ((index % all.length) + all.length) % all.length;
    const e = engineRef.current;
    if (e) {
      e.time = 0;
      e.duration = all[nextIndex]?.duration ?? 1;
    }
    trackIndexRef.current = nextIndex;
    setTrackIndex(nextIndex);
    onTrackChangeRef.current?.(nextIndex);
    wakeRef.current();
  }, []);

  // One rAF loop drives the clock, the meter and the disc whenever it is
  // off cruise. It sleeps once everything rests, and while off screen.
  React.useEffect(() => {
    const e = engineRef.current;
    if (!e) {
      return;
    }
    let raf = 0;
    let last = 0;

    const render = () => {
      paint(e, discRef.current, fillRef.current, rpmRef.current);
      const s = Math.floor(e.time);
      if (s !== clockRef.current) {
        const dir = s > clockRef.current ? 1 : -1;
        clockRef.current = s;
        setClock({ s, dir });
      }
    };

    const handleEnds = () => {
      if (e.time >= e.duration) {
        if (e.playing && !e.held && !e.barDrag) {
          loadTrack(trackIndexRef.current + 1);
          return;
        }
        e.time = e.duration;
      }
      if (e.time < 0) {
        e.time = 0;
      }
    };

    const isAwake = () =>
      e.playing || e.held || e.barDrag || e.omega !== 0 || e.env > 0;

    const tick = (now: number) => {
      const dt = last ? Math.min((now - last) / 1000, MAX_DT) : 0;
      last = now;
      if (e.held) {
        e.scrubOmega *= Math.exp(-dt / HOLD_SETTLE_S);
      } else if (!e.barDrag) {
        integrateDisc(e, dt, discRef.current);
      }
      handleEnds();
      updateMeter(e, dt, barRefs.current);
      render();
      if (isAwake() && e.visible) {
        raf = requestAnimationFrame(tick);
      } else {
        raf = 0;
        last = 0;
      }
    };

    const wake = () => {
      render();
      if (raf === 0 && e.visible) {
        last = 0;
        raf = requestAnimationFrame(tick);
      }
    };
    wakeRef.current = wake;

    let inView = true;
    const sync = () => {
      e.visible = inView && !document.hidden;
      if (e.visible) {
        e.cruise?.play();
        wake();
      } else {
        e.cruise?.pause();
        cancelAnimationFrame(raf);
        raf = 0;
      }
    };
    const observer = new IntersectionObserver(([entry]) => {
      inView = entry?.isIntersecting ?? true;
      sync();
    });
    if (rootRef.current) {
      observer.observe(rootRef.current);
    }
    document.addEventListener("visibilitychange", sync);

    const media = window.matchMedia("(prefers-reduced-motion: reduce)");
    const syncMotion = () => {
      e.reduced = media.matches;
      if (e.reduced) {
        stopCruise(e, discRef.current);
      }
      wake();
    };
    syncMotion();
    media.addEventListener("change", syncMotion);

    return () => {
      cancelAnimationFrame(raf);
      observer.disconnect();
      document.removeEventListener("visibilitychange", sync);
      media.removeEventListener("change", syncMotion);
      e.cruise?.cancel();
      e.cruise = null;
    };
  }, [loadTrack]);

  const togglePlay = () => {
    const e = engineRef.current;
    if (!e) {
      return;
    }
    const nextPlaying = !e.playing;
    if (nextPlaying && e.time >= e.duration) {
      e.time = 0;
    }
    e.playing = nextPlaying;
    if (!nextPlaying) {
      // Hand the disc back to the loop so it can spin down.
      stopCruise(e, discRef.current);
    }
    setPlaying(nextPlaying);
    wakeRef.current();
  };

  const previous = () => {
    const e = engineRef.current;
    if (e && e.time > RESTART_THRESHOLD) {
      e.time = 0;
      wakeRef.current();
      return;
    }
    loadTrack(trackIndexRef.current - 1);
  };

  const next = () => loadTrack(trackIndexRef.current + 1);

  /* ---------------------------- Disc scrubbing ---------------------------- */

  const pointerAngle = (e: Engine, clientX: number, clientY: number) => {
    const dx = clientX - e.center.x;
    const dy = clientY - e.center.y;
    return {
      angle: (Math.atan2(dy, dx) * 180) / Math.PI,
      distance: Math.hypot(dx, dy),
    };
  };

  const onDiscDown = (event: React.PointerEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (!e || event.button !== 0 || e.pointerId !== null) {
      return;
    }
    e.pointerId = event.pointerId;
    event.currentTarget.setPointerCapture(event.pointerId);
    const rect = event.currentTarget.getBoundingClientRect();
    e.center = { x: rect.left + rect.width / 2, y: rect.top + rect.height / 2 };
    // A finger on the record stops it dead, cruise animation included.
    stopCruise(e, discRef.current);
    e.held = true;
    e.omega = 0;
    e.scrubOmega = 0;
    e.pointerAngle = pointerAngle(e, event.clientX, event.clientY).angle;
    e.lastMoveAt = performance.now();
    e.samples = [{ t: e.lastMoveAt, a: e.angle }];
    wakeRef.current();
  };

  const onDiscMove = (event: React.PointerEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (!e?.held || e.pointerId !== event.pointerId) {
      return;
    }
    const { angle, distance } = pointerAngle(e, event.clientX, event.clientY);
    if (distance < DEAD_ZONE) {
      e.pointerAngle = angle;
      return;
    }
    // Unwrap across the ±180° seam.
    let delta = angle - e.pointerAngle;
    delta -= Math.round(delta / 360) * 360;
    e.pointerAngle = angle;

    const now = performance.now();
    const dt = Math.max(now - e.lastMoveAt, 1) / 1000;
    e.lastMoveAt = now;
    const instant = clamp(delta / dt, -MAX_OMEGA, MAX_OMEGA);
    e.scrubOmega += (instant - e.scrubOmega) * 0.35;

    // Track time follows the angle; faster turns cover more of the song.
    e.angle += delta;
    e.time = clamp(
      e.time + (delta / CRUISE) * scrubGain(e.scrubOmega),
      0,
      e.duration
    );

    e.samples.push({ t: now, a: e.angle });
    while (
      e.samples.length > 2 &&
      now - (e.samples[0]?.t ?? now) > VELOCITY_WINDOW_MS
    ) {
      e.samples.shift();
    }
    if (discRef.current) {
      discRef.current.style.transform = rotate(e.angle);
    }
  };

  const onDiscUp = (event: React.PointerEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (!e?.held || e.pointerId !== event.pointerId) {
      return;
    }
    e.pointerId = null;
    if (event.currentTarget.hasPointerCapture(event.pointerId)) {
      event.currentTarget.releasePointerCapture(event.pointerId);
    }
    e.held = false;
    const now = performance.now();
    const first = e.samples[0];
    let velocity = 0;
    if (first && now - e.lastMoveAt < STALE_MOVE_MS && now > first.t) {
      velocity = ((e.angle - first.a) / (now - first.t)) * 1000;
    }
    // It keeps the spin you gave it, then eases back to cruise.
    e.omega = e.reduced ? 0 : clamp(velocity, -MAX_OMEGA, MAX_OMEGA);
    e.scrubOmega = 0;
    wakeRef.current();
  };

  /* ----------------------------- Scrubber bar ----------------------------- */

  const seekFromPointer = (clientX: number) => {
    const e = engineRef.current;
    const rail = railRef.current;
    if (!(e && rail?.parentElement)) {
      return;
    }
    // The rail stretches, so measure its parent, which never moves.
    const rect = rail.parentElement.getBoundingClientRect();
    const x = clientX - rect.left;
    e.time = clamp(x / rect.width, 0, 1) * e.duration;

    // Past either end the rail stretches toward the pointer and thins,
    // giving less the further you pull.
    let over = 0;
    if (x < 0) {
      over = -damp(-x, RUBBER_MAX);
    } else if (x > rect.width) {
      over = damp(x - rect.width, RUBBER_MAX);
    }
    const stretch = 1 + Math.abs(over) / rect.width;
    const thin = 1 - (0.35 * Math.abs(over)) / RUBBER_MAX;
    rail.style.transition = "none";
    rail.style.transformOrigin = over < 0 ? "right center" : "left center";
    rail.style.transform =
      over === 0 ? "" : `scale(${stretch.toFixed(4)}, ${thin.toFixed(3)})`;
    wakeRef.current();
  };

  const onBarDown = (event: React.PointerEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (!e || event.button !== 0 || e.pointerId !== null) {
      return;
    }
    e.pointerId = event.pointerId;
    event.currentTarget.setPointerCapture(event.pointerId);
    e.barDrag = true;
    seekFromPointer(event.clientX);
  };

  const onBarMove = (event: React.PointerEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (e?.barDrag && e.pointerId === event.pointerId) {
      seekFromPointer(event.clientX);
    }
  };

  const onBarUp = (event: React.PointerEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (!e?.barDrag || e.pointerId !== event.pointerId) {
      return;
    }
    e.pointerId = null;
    e.barDrag = false;
    const rail = railRef.current;
    if (rail) {
      rail.style.transition = RUBBER_RETURN;
      rail.style.transform = "";
    }
    wakeRef.current();
  };

  const onBarKey = (event: React.KeyboardEvent<HTMLDivElement>) => {
    const e = engineRef.current;
    if (!e) {
      return;
    }
    const targets: Record<string, number> = {
      ArrowRight: e.time + SEEK_STEP,
      ArrowUp: e.time + SEEK_STEP,
      ArrowLeft: e.time - SEEK_STEP,
      ArrowDown: e.time - SEEK_STEP,
      Home: 0,
      End: e.duration - 1,
    };
    const target = targets[event.key];
    if (target === undefined) {
      return;
    }
    event.preventDefault();
    e.time = clamp(target, 0, e.duration);
    wakeRef.current();
  };

  const body = (
    <>
      <style>{ROLL_KEYFRAMES}</style>
      <div className="flex items-center gap-5">
        <div className="relative @[22rem]/now-playing:size-32 size-28 shrink-0">
          <div
            className="size-full cursor-grab touch-none select-none rounded-full shadow-[0_6px_16px_-6px_rgba(0,0,0,0.45)] active:cursor-grabbing"
            data-now-playing-disc=""
            onLostPointerCapture={onDiscUp}
            onPointerCancel={onDiscUp}
            onPointerDown={onDiscDown}
            onPointerMove={onDiscMove}
            onPointerUp={onDiscUp}
            ref={discRef}
            title="Spin to scrub"
          >
            <Disc artwork={track.artwork ?? trackIndex % 3} />
          </div>
          <Tonearm down={playing} />
        </div>

        <div className="min-w-0 flex-1">
          <div className="flex items-center gap-2">
            <span aria-hidden="true" className="flex h-3.5 items-end gap-0.5">
              {Array.from({ length: BAR_COUNT }, (_, i) => (
                <span
                  className="h-full w-[3px] origin-bottom rounded-[1px] bg-(--now-playing-accent)"
                  // biome-ignore lint/suspicious/noArrayIndexKey: fixed set of bars
                  key={i}
                  ref={(node) => {
                    barRefs.current[i] = node;
                  }}
                  style={{ transform: `scaleY(${BAR_REST})` }}
                />
              ))}
            </span>
            <span className="font-medium text-[11px] text-zinc-500 uppercase tracking-wider dark:text-zinc-400">
              Now playing
            </span>
          </div>
          <h3 className="mt-2 truncate font-semibold text-base text-zinc-900 dark:text-zinc-50">
            {track.title}
          </h3>
          <p className="truncate text-sm text-zinc-500 dark:text-zinc-400">
            {track.artist}
          </p>
          <span
            className="mt-2 inline-block font-mono text-[11px] text-zinc-400 tabular-nums dark:text-zinc-500"
            ref={rpmRef}
          >
            {autoPlay ? "33⅓ rpm" : "0 rpm"}
          </span>
        </div>
      </div>

      <div className="mt-5">
        <div
          aria-label="Seek"
          aria-valuemax={track.duration}
          aria-valuemin={0}
          aria-valuenow={clock.s}
          aria-valuetext={`${formatTime(clock.s)} of ${formatTime(track.duration)}`}
          className="group/seek -my-2 cursor-pointer touch-none py-2 outline-none"
          onKeyDown={onBarKey}
          onLostPointerCapture={onBarUp}
          onPointerCancel={onBarUp}
          onPointerDown={onBarDown}
          onPointerMove={onBarMove}
          onPointerUp={onBarUp}
          role="slider"
          tabIndex={0}
        >
          <div className="h-1.5">
            <div
              className="h-full overflow-hidden rounded-full bg-zinc-200 ring-zinc-400 ring-offset-2 ring-offset-white group-focus-visible/seek:ring-2 dark:bg-zinc-800 dark:ring-offset-zinc-900"
              ref={railRef}
            >
              <div
                className="h-full w-full origin-left bg-(--now-playing-accent)"
                ref={fillRef}
                style={{ transform: "scaleX(0)" }}
              />
            </div>
          </div>
        </div>
        <div className="mt-2 flex justify-between font-medium text-xs text-zinc-500 tabular-nums dark:text-zinc-400">
          <RollingTime direction={clock.dir} seconds={clock.s} />
          <span>{formatTime(track.duration)}</span>
        </div>
      </div>

      <div className="mt-3 flex items-center justify-center gap-3">
        <button
          aria-label="Previous track"
          className={ICON_BUTTON}
          onClick={previous}
          type="button"
        >
          <SkipBack className="size-5" fill="currentColor" />
        </button>
        <button
          aria-label={playing ? "Pause" : "Play"}
          className="inline-flex size-12 items-center justify-center rounded-full bg-zinc-900 text-white transition-colors duration-150 hover:bg-zinc-700 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 focus-visible:ring-offset-white active:bg-zinc-600 dark:bg-zinc-100 dark:text-zinc-900 dark:active:bg-zinc-300 dark:focus-visible:ring-offset-zinc-900 dark:hover:bg-white"
          onClick={togglePlay}
          type="button"
        >
          {playing ? (
            <Pause className="size-5" fill="currentColor" />
          ) : (
            <Play className="size-5 translate-x-px" fill="currentColor" />
          )}
        </button>
        <button
          aria-label="Next track"
          className={ICON_BUTTON}
          onClick={next}
          type="button"
        >
          <SkipForward className="size-5" fill="currentColor" />
        </button>
      </div>
    </>
  );

  const style = { "--now-playing-accent": accent } as React.CSSProperties;

  if (glassEffect) {
    return (
      <div className="w-full max-w-sm" ref={rootRef} style={style}>
        <LiquidGlassCard
          className={cn(FRAME, "bg-white/50 dark:bg-zinc-900/50", className)}
          glassEffect
          glassSize="sm"
        >
          {body}
        </LiquidGlassCard>
      </div>
    );
  }

  return (
    <div
      className={cn(FRAME, "bg-white dark:bg-zinc-900", className)}
      ref={rootRef}
      style={style}
    >
      {body}
    </div>
  );
}

export { LiquidButton, LiquidGlassCard, NowPlaying as NotificationCenter };
export default NowPlaying;
```


---

# Metric Card
> A KPI card whose number rolls to any day you scrub, with periods that reshape the line instead of swapping it.

Source: https://kokonutui.com/docs/cards/metric-card

## Installation

```bash
npx shadcn@latest add @kokonutui/metric-card
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Metric Card
 * @version: 1.0.0
 * @date: 2026-10-15
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  useCallback,
  useEffect,
  useId,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// The chart's drawing box; it stretches to the card's width.
const W = 400;
const H = 120;
const PAD_Y = 10;
// Every period is resampled to this many points, so one shape can morph
// into another.
const SAMPLES = 90;
const MORPH_MS = 420;
const DAY = 86_400_000;
const DIGIT = /\d/;

export interface MetricPoint {
  /** YYYY-MM-DD */
  date: string;
  value: number;
}

export interface MetricCardProps {
  label?: string;
  /** Daily values, oldest first. Needs twice the longest period, so each period has one to compare with. */
  data?: MetricPoint[];
  periods?: number[];
  defaultPeriod?: number;
  /** "currency" sums the period; "number" sums it too, without a symbol. */
  format?: "currency" | "number";
  currency?: string;
  className?: string;
}

const clamp = (v: number, lo: number, hi: number) =>
  Math.min(hi, Math.max(lo, v));

// Seeded, so server and browser draw the same chart.
function demoData(days: number, end: string): MetricPoint[] {
  let seed = 42;
  const random = () => {
    seed = (seed * 16_807) % 2_147_483_647;
    return seed / 2_147_483_647;
  };
  const last = Date.parse(`${end}T00:00:00Z`);
  const out: MetricPoint[] = [];
  let level = 1180;
  for (let i = 0; i < days; i++) {
    const t = last - (days - 1 - i) * DAY;
    const weekday = new Date(t).getUTCDay();
    const weekend = weekday === 0 || weekday === 6;
    level += 3.4 + (random() - 0.5) * 30;
    const promo = i > days - 40 && i < days - 34 ? 1.22 : 1;
    const value =
      level * (weekend ? 0.86 : 1) * promo * (0.94 + random() * 0.12);
    out.push({
      date: new Date(t).toISOString().slice(0, 10),
      value: Math.round(value),
    });
  }
  return out;
}

const DEFAULT_DATA = demoData(180, "2026-10-14");

const formatDay = (date: string) =>
  new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
    weekday: "short",
    month: "short",
    day: "numeric",
    timeZone: "UTC",
  });

const formatShort = (date: string) =>
  new Date(`${date}T00:00:00Z`).toLocaleDateString("en-US", {
    month: "short",
    day: "numeric",
    timeZone: "UTC",
  });

/** Linear resample of `values` to `count` evenly spaced points. */
function resample(values: number[], count: number) {
  const out = new Array<number>(count);
  for (let i = 0; i < count; i++) {
    const at = (i / (count - 1)) * (values.length - 1);
    const lo = Math.floor(at);
    const hi = Math.min(values.length - 1, lo + 1);
    out[i] = values[lo] + (values[hi] - values[lo]) * (at - lo);
  }
  return out;
}

/** Heights 0..1 to an SVG path, smoothed with a Catmull-Rom spline. */
function toPath(heights: number[]) {
  const pts = heights.map((h, i) => [
    (i / (heights.length - 1)) * W,
    PAD_Y + (1 - h) * (H - PAD_Y * 2),
  ]);
  let d = `M${pts[0][0].toFixed(2)} ${pts[0][1].toFixed(2)}`;
  for (let i = 0; i < pts.length - 1; i++) {
    const p0 = pts[i - 1] ?? pts[i];
    const p1 = pts[i];
    const p2 = pts[i + 1];
    const p3 = pts[i + 2] ?? p2;
    const c1x = p1[0] + (p2[0] - p0[0]) / 6;
    const c1y = p1[1] + (p2[1] - p0[1]) / 6;
    const c2x = p2[0] - (p3[0] - p1[0]) / 6;
    const c2y = p2[1] - (p3[1] - p1[1]) / 6;
    d += `C${c1x.toFixed(2)} ${c1y.toFixed(2)} ${c2x.toFixed(2)} ${c2y.toFixed(2)} ${p2[0].toFixed(2)} ${p2[1].toFixed(2)}`;
  }
  return d;
}

interface Shape {
  current: number[];
  previous: number[];
}

interface Paths {
  current: string;
  previous: string;
}

/** One period's numbers and its shape, normalised to the same scale. */
function buildPeriod(data: MetricPoint[], days: number) {
  const current = data.slice(-days);
  const previous = data.slice(-days * 2, -days);
  const values = [...current, ...previous].map((p) => p.value);
  const lo = Math.min(...values) * 0.92;
  const hi = Math.max(...values) * 1.04;
  const norm = (v: number) => (v - lo) / (hi - lo || 1);
  const total = current.reduce((s, p) => s + p.value, 0);
  const before = previous.reduce((s, p) => s + p.value, 0);
  return {
    current,
    previous,
    total,
    before,
    // Resampled to a common length for morphing between periods.
    shape: {
      current: resample(
        current.map((p) => norm(p.value)),
        SAMPLES
      ),
      previous: resample(
        previous.map((p) => norm(p.value)),
        SAMPLES
      ),
    } as Shape,
    // Drawn through the real days once it lands, so the dots sit on it.
    paths: {
      current: toPath(current.map((p) => norm(p.value))),
      previous: toPath(previous.map((p) => norm(p.value))),
    } as Paths,
    norm,
  };
}

const easeInOut = (t: number) =>
  t < 0.5 ? 4 * t * t * t : 1 - (-2 * t + 2) ** 3 / 2;

/** Each digit rolls on its own wheel; separators sit still. */
function RollingNumber({ value }: { value: string }) {
  const chars = value.split("");
  return (
    <span aria-hidden className="inline-flex tabular-nums">
      {chars.map((char, i) => {
        // Keyed from the right, so units stay put when the length changes.
        const key = chars.length - i;
        if (!DIGIT.test(char)) {
          return <span key={`s${key}`}>{char}</span>;
        }
        return (
          <span
            className="relative inline-block h-[1em] overflow-hidden leading-none"
            key={`d${key}`}
          >
            <span className="invisible">0</span>
            <span
              className="absolute inset-x-0 top-0 flex flex-col transition-transform duration-[380ms] ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none"
              style={{ transform: `translateY(-${Number(char) * 10}%)` }}
            >
              {DIGITS.map((d) => (
                <span className="block h-[1em] leading-none" key={d}>
                  {d}
                </span>
              ))}
            </span>
          </span>
        );
      })}
    </span>
  );
}

const DIGITS = ["0", "1", "2", "3", "4", "5", "6", "7", "8", "9"];

export default function MetricCard({
  label = "Revenue",
  data = DEFAULT_DATA,
  periods = [7, 30, 90],
  defaultPeriod = 30,
  format = "currency",
  currency = "USD",
  className,
}: MetricCardProps) {
  const clipId = `${useId().replace(/:/g, "")}-past`;
  const [period, setPeriod] = useState(defaultPeriod);
  const [scrub, setScrub] = useState<number | null>(null);
  const info = useMemo(() => buildPeriod(data, period), [data, period]);

  const currentRef = useRef<SVGPathElement>(null);
  const currentDimRef = useRef<SVGPathElement>(null);
  const previousRef = useRef<SVGPathElement>(null);
  const chartRef = useRef<HTMLDivElement>(null);
  const shown = useRef<Shape>(info.shape);
  const morph = useRef({ raf: 0 });

  const money = useMemo(
    () =>
      new Intl.NumberFormat("en-US", {
        style: format === "currency" ? "currency" : "decimal",
        currency,
        maximumFractionDigits: 0,
      }),
    [format, currency]
  );

  // A new period morphs the lines from where they are now.
  useEffect(() => {
    const from = shown.current;
    const to = info.shape;
    const m = morph.current;
    cancelAnimationFrame(m.raf);
    const paint = (paths: Paths) => {
      currentRef.current?.setAttribute("d", paths.current);
      currentDimRef.current?.setAttribute("d", paths.current);
      previousRef.current?.setAttribute("d", paths.previous);
    };
    const land = () => {
      shown.current = to;
      paint(info.paths);
    };
    if (
      from === to ||
      window.matchMedia("(prefers-reduced-motion: reduce)").matches
    ) {
      land();
      return;
    }
    const start = performance.now();
    const frame = (now: number) => {
      const t = easeInOut(Math.min(1, (now - start) / MORPH_MS));
      const mix = (a: number[], b: number[]) =>
        a.map((v, i) => v + (b[i] - v) * t);
      shown.current = {
        current: mix(from.current, to.current),
        previous: mix(from.previous, to.previous),
      };
      if (t < 1) {
        paint({
          current: toPath(shown.current.current),
          previous: toPath(shown.current.previous),
        });
        m.raf = requestAnimationFrame(frame);
      } else {
        land();
      }
    };
    m.raf = requestAnimationFrame(frame);
    return () => cancelAnimationFrame(m.raf);
  }, [info.shape, info.paths]);

  const indexAt = useCallback(
    (clientX: number) => {
      const rect = chartRef.current?.getBoundingClientRect();
      if (!rect) {
        return 0;
      }
      const t = clamp((clientX - rect.left) / rect.width, 0, 1);
      return Math.round(t * (info.current.length - 1));
    },
    [info.current.length]
  );

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    event.currentTarget.setPointerCapture(event.pointerId);
    setScrub(indexAt(event.clientX));
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    // Mouse scrubs on hover; touch only while pressed.
    if (
      event.pointerType === "mouse" ||
      event.currentTarget.hasPointerCapture(event.pointerId)
    ) {
      setScrub(indexAt(event.clientX));
    }
  };

  const release = (event: PointerEvent<HTMLDivElement>) => {
    if (event.pointerType !== "mouse") {
      setScrub(null);
    }
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    const last = info.current.length - 1;
    const moves: Record<string, number> = {
      ArrowLeft: -1,
      ArrowRight: 1,
      Home: -last,
      End: last,
    };
    if (event.key === "Escape") {
      setScrub(null);
      return;
    }
    const move = moves[event.key];
    if (move === undefined) {
      return;
    }
    event.preventDefault();
    setScrub((at) => clamp((at ?? last) + move, 0, last));
  };

  const choose = (days: number) => {
    setScrub(null);
    setPeriod(days);
  };

  const scrubbing = scrub !== null && scrub < info.current.length;
  const point = scrubbing ? info.current[scrub] : null;
  const twin = scrubbing ? info.previous[scrub] : null;
  const value = point ? point.value : info.total;
  const compare = twin ? twin.value : info.before;
  const delta = compare ? (value - compare) / compare : 0;
  const up = delta >= 0;
  const x = scrubbing ? (scrub / (info.current.length - 1)) * 100 : 100;
  const y = point ? PAD_Y + (1 - info.norm(point.value)) * (H - PAD_Y * 2) : 0;
  const yPrev = twin
    ? PAD_Y + (1 - info.norm(twin.value)) * (H - PAD_Y * 2)
    : 0;
  const first = info.current[0];
  const lastPoint = info.current.at(-1);
  const formatted = money.format(value);

  return (
    <div
      className={cn(
        "w-full max-w-md select-none rounded-3xl border border-zinc-200 bg-white p-5 text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
    >
      <div className="flex items-center justify-between gap-4">
        <p className="text-sm text-zinc-500 dark:text-zinc-400">{label}</p>
        <div className="flex rounded-full bg-zinc-100 p-0.5 text-xs dark:bg-zinc-900">
          {periods.map((days) => (
            <button
              aria-pressed={days === period}
              className={cn(
                "rounded-full px-2.5 py-1 font-medium tabular-nums outline-none transition-colors duration-200 ease-out focus-visible:ring-2 focus-visible:ring-zinc-400",
                days === period
                  ? "bg-white text-zinc-900 shadow-sm dark:bg-zinc-700 dark:text-zinc-50"
                  : "text-zinc-500 hover:text-zinc-900 dark:text-zinc-400 dark:hover:text-zinc-100"
              )}
              key={days}
              onClick={() => choose(days)}
              type="button"
            >
              {days}D
            </button>
          ))}
        </div>
      </div>

      <p className="mt-3 font-semibold text-4xl tracking-tight">
        <span className="sr-only">{formatted}</span>
        <RollingNumber value={formatted} />
      </p>
      <div className="mt-1.5 flex items-center gap-2 text-sm tabular-nums">
        <span
          className={cn(
            "font-medium",
            up
              ? "text-emerald-600 dark:text-emerald-400"
              : "text-rose-600 dark:text-rose-400"
          )}
        >
          {up ? "▲" : "▼"} {Math.abs(delta * 100).toFixed(1)}%
        </span>
        <span aria-live="polite" className="text-zinc-500 dark:text-zinc-400">
          {point
            ? `${formatDay(point.date)} vs ${formatShort(twin?.date ?? point.date)}`
            : `vs previous ${period} days`}
        </span>
      </div>

      <div
        aria-label={`${label} over the last ${period} days. Use the arrow keys to read each day.`}
        aria-valuemax={info.current.length}
        aria-valuemin={1}
        aria-valuenow={scrubbing ? scrub + 1 : info.current.length}
        aria-valuetext={
          point
            ? `${formatDay(point.date)}: ${money.format(point.value)}`
            : `${money.format(info.total)} in total`
        }
        className="relative mt-5 h-32 cursor-crosshair touch-pan-y rounded-lg outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-4 dark:focus-visible:ring-offset-zinc-950"
        onBlur={() => setScrub(null)}
        onKeyDown={handleKeyDown}
        onLostPointerCapture={release}
        onPointerCancel={release}
        onPointerDown={handlePointerDown}
        onPointerLeave={() => setScrub(null)}
        onPointerMove={handlePointerMove}
        onPointerUp={release}
        ref={chartRef}
        role="slider"
        tabIndex={0}
      >
        <svg
          aria-hidden="true"
          className="absolute inset-0 h-full w-full overflow-visible"
          preserveAspectRatio="none"
          viewBox={`0 0 ${W} ${H}`}
        >
          <defs>
            <clipPath id={clipId}>
              <rect height={H + 20} width={(x / 100) * W} x={0} y={-10} />
            </clipPath>
          </defs>
          <line
            className="stroke-zinc-200 dark:stroke-zinc-800"
            vectorEffect="non-scaling-stroke"
            x1={0}
            x2={W}
            y1={H - 0.5}
            y2={H - 0.5}
          />
          <path
            className="fill-none stroke-zinc-300 dark:stroke-zinc-700"
            d={info.paths.previous}
            ref={previousRef}
            strokeDasharray="3 4"
            strokeWidth={1.25}
            vectorEffect="non-scaling-stroke"
          />
          {/* After the scrubbed day the line fades back. */}
          <path
            className="fill-none stroke-zinc-900/25 dark:stroke-zinc-100/25"
            d={info.paths.current}
            ref={currentDimRef}
            strokeLinecap="round"
            strokeWidth={2}
            vectorEffect="non-scaling-stroke"
          />
          <path
            className="fill-none stroke-zinc-900 dark:stroke-zinc-100"
            clipPath={`url(#${clipId})`}
            d={info.paths.current}
            ref={currentRef}
            strokeLinecap="round"
            strokeWidth={2}
            vectorEffect="non-scaling-stroke"
          />
        </svg>

        {point && (
          <>
            <div
              aria-hidden
              className="pointer-events-none absolute top-0 bottom-0 w-px bg-zinc-200 dark:bg-zinc-800"
              style={{ left: `${x}%` }}
            />
            <div
              aria-hidden
              className="pointer-events-none absolute size-2 -translate-x-1/2 -translate-y-1/2 rounded-full border border-zinc-300 bg-white dark:border-zinc-600 dark:bg-zinc-950"
              style={{ left: `${x}%`, top: `${(yPrev / H) * 100}%` }}
            />
            <div
              aria-hidden
              className="pointer-events-none absolute size-2.5 -translate-x-1/2 -translate-y-1/2 rounded-full bg-zinc-900 ring-4 ring-white dark:bg-zinc-100 dark:ring-zinc-950"
              style={{ left: `${x}%`, top: `${(y / H) * 100}%` }}
            />
          </>
        )}
      </div>

      <div className="mt-2 flex justify-between text-xs text-zinc-400 tabular-nums dark:text-zinc-500">
        <span>{first ? formatShort(first.date) : ""}</span>
        <span className="flex items-center gap-1.5">
          <span className="h-px w-3 border-zinc-300 border-t border-dashed dark:border-zinc-700" />
          Previous period
        </span>
        <span>{lastPoint ? formatShort(lastPoint.date) : ""}</span>
      </div>
    </div>
  );
}
```


---

# Notification Stack
> Stacked notifications that fan out on hover and swipe away, built with React and Tailwind CSS.

Source: https://kokonutui.com/docs/cards/notification-stack

## Installation

```bash
npx shadcn@latest add @kokonutui/notification-stack
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Notification Stack
 * @version: 1.1.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { CalendarDays, CreditCard, Mail, MessageCircle, X } from "lucide-react";
import {
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface StackNotification {
  id: string;
  app: string;
  title: string;
  body: string;
  time: string;
  icon?: ReactNode;
}

const DEFAULT_NOTIFICATIONS: StackNotification[] = [
  {
    id: "n-1",
    app: "Messages",
    title: "Maya Chen",
    body: "Pushed the fix. Can you take a look before standup?",
    time: "now",
    icon: (
      <span className="flex size-8 items-center justify-center rounded-lg bg-emerald-500 text-white">
        <MessageCircle className="size-4" />
      </span>
    ),
  },
  {
    id: "n-2",
    app: "Calendar",
    title: "Design review in 10 min",
    body: "Room 4B · Kokonut UI roadmap",
    time: "9:50",
    icon: (
      <span className="flex size-8 items-center justify-center rounded-lg bg-red-500 text-white">
        <CalendarDays className="size-4" />
      </span>
    ),
  },
  {
    id: "n-3",
    app: "Mail",
    title: "Invoice #2041 paid",
    body: "Acme Inc. paid $1,280.00. The receipt is attached.",
    time: "9:12",
    icon: (
      <span className="flex size-8 items-center justify-center rounded-lg bg-sky-500 text-white">
        <Mail className="size-4" />
      </span>
    ),
  },
  {
    id: "n-4",
    app: "Wallet",
    title: "Card payment",
    body: "$4.50 at Blue Bottle Coffee",
    time: "8:31",
    icon: (
      <span className="flex size-8 items-center justify-center rounded-lg bg-zinc-900 text-white dark:bg-zinc-100 dark:text-zinc-900">
        <CreditCard className="size-4" />
      </span>
    ),
  },
];

// Collapsed: how much of each card behind the front one peeks out.
const PEEK = 10;
const VISIBLE_BEHIND = 2;
const GAP = 8;
// Used until a card has been measured, so server and client agree.
const FALLBACK_HEIGHT = 76;

// A swipe dismisses when it travels this far, or when it is a quick flick
// (px per ms), whichever comes first. A flick shouldn't need to go far.
const DISMISS_DISTANCE = 100;
const DISMISS_VELOCITY = 0.11;
// Movement before we decide whether the gesture is a horizontal swipe or a
// vertical scroll.
const AXIS_LOCK = 6;
// Snap-back spring (critically damped, so it never wobbles past rest but
// still carries the release momentum a little further before it turns).
const SPRING_STIFFNESS = 520;
const SPRING_DAMPING = 2 * Math.sqrt(SPRING_STIFFNESS);
// Dismiss flight: a released card keeps its own speed (px/s), never slower
// than this, and picks up a little speed as it goes.
const FLIGHT_MIN_SPEED = 1400;
const FLIGHT_ACCEL = 4200;
// Velocity is read from the last stretch of the gesture, not the average.
const VELOCITY_WINDOW_MS = 80;
const EXIT_MS = 200;
const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";

interface Drag {
  pointerId: number;
  startX: number;
  startY: number;
  /** Where the card already was when grabbed (mid snap-back). */
  originX: number;
  dx: number;
  axis: "x" | "y" | null;
  samples: { t: number; x: number }[];
}

const opacityFor = (x: number) => Math.max(1 - Math.abs(x) / 240, 0.3);

/** Release velocity in px/ms from the most recent pointer samples. */
function releaseVelocity(samples: { t: number; x: number }[]) {
  const last = samples.at(-1);
  if (!last) {
    return 0;
  }
  let first = last;
  for (let i = samples.length - 1; i >= 0; i--) {
    const sample = samples[i];
    if (last.t - sample.t > VELOCITY_WINDOW_MS) {
      break;
    }
    first = sample;
  }
  const dt = last.t - first.t;
  return dt > 0 ? (last.x - first.x) / dt : 0;
}

/**
 * Which way a released card leaves, or 0 to spring back. A flick counts
 * only when it moves away from rest; flicking a dragged card back toward
 * the middle returns it.
 */
function dismissDirection(dx: number, velocity: number): 1 | -1 | 0 {
  const flick =
    Math.abs(velocity) > DISMISS_VELOCITY &&
    Math.sign(velocity) === Math.sign(dx);
  if (Math.abs(dx) < DISMISS_DISTANCE && !flick) {
    return 0;
  }
  return (dx === 0 ? velocity : dx) > 0 ? 1 : -1;
}

const prefersReducedMotion = () =>
  typeof window !== "undefined" &&
  window.matchMedia("(prefers-reduced-motion: reduce)").matches;

export interface NotificationStackProps {
  /** Initial notifications, newest first. The stack tracks dismissals itself. */
  notifications?: StackNotification[];
  /** Called after a notification has been swiped or clicked away. */
  onDismiss?: (id: string) => void;
  className?: string;
}

export default function NotificationStack({
  notifications = DEFAULT_NOTIFICATIONS,
  onDismiss,
  className,
}: NotificationStackProps) {
  const [items, setItems] = useState(notifications);
  const [heights, setHeights] = useState<Record<string, number>>({});
  const [hovered, setHovered] = useState(false);
  const [focused, setFocused] = useState(false);
  const [pinned, setPinned] = useState(false);
  const [leaving, setLeaving] = useState<Set<string>>(() => new Set());

  const listRef = useRef<HTMLOListElement>(null);
  const swipeRefs = useRef(new Map<string, HTMLDivElement>());
  const drag = useRef<Drag | null>(null);
  const suppressClick = useRef(false);
  const timers = useRef<number[]>([]);
  // Where each card last sat, so a leaving card slides out from there.
  const lastY = useRef(new Map<string, number>());
  // Live horizontal offset of each card, and its running animation frame.
  const swipeX = useRef(new Map<string, number>());
  const frames = useRef(new Map<string, number>());
  // Cards already on their way out, so a repeated Delete or a double click
  // can't dismiss (and report) the same card twice.
  const dismissed = useRef(new Set<string>());
  // Ends a gesture whose pointer was released off the card before it was
  // captured (a vertical drag that left the card).
  const stopListening = useRef<(() => void) | null>(null);

  useEffect(() => {
    const pending = timers.current;
    const running = frames.current;
    return () => {
      for (const id of pending) {
        window.clearTimeout(id);
      }
      for (const frame of running.values()) {
        cancelAnimationFrame(frame);
      }
      stopListening.current?.();
    };
  }, []);

  // Measure each card once on mount, then only when it actually resizes
  // (text rewrapping), instead of reading layout on every render. Cards are
  // only ever removed, so the initial set is all there is to observe.
  useLayoutEffect(() => {
    const list = listRef.current;
    if (!list) {
      return;
    }
    const measure = (entries: { id?: string; height: number }[]) => {
      setHeights((prev) => {
        let next = prev;
        for (const { id, height } of entries) {
          if (id && height && prev[id] !== height) {
            next = next === prev ? { ...prev } : next;
            next[id] = height;
          }
        }
        return next;
      });
    };
    const cards = Array.from(list.children) as HTMLElement[];
    measure(
      cards.map((card) => ({ id: card.dataset.id, height: card.offsetHeight }))
    );
    const observer = new ResizeObserver((entries) => {
      measure(
        entries.map((entry) => ({
          id: (entry.target as HTMLElement).dataset.id,
          height: Math.round(entry.borderBoxSize[0]?.blockSize ?? 0),
        }))
      );
    });
    for (const card of cards) {
      observer.observe(card);
    }
    return () => observer.disconnect();
  }, []);

  const expanded = (hovered || focused || pinned) && items.length > 1;
  const heightOf = (id: string) => heights[id] ?? FALLBACK_HEIGHT;

  // Cards that are on their way out no longer take up room, so the rest
  // close the gap while the leaving card slides away.
  const laidOut = items.filter((item) => !leaving.has(item.id));
  const frontHeight = laidOut[0] ? heightOf(laidOut[0].id) : 0;
  const stackHeight = expanded
    ? laidOut.reduce((sum, item) => sum + heightOf(item.id), 0) +
      Math.max(laidOut.length - 1, 0) * GAP
    : frontHeight + Math.min(laidOut.length - 1, VISIBLE_BEHIND) * PEEK;

  const offsets: number[] = [];
  let running = 0;
  for (const item of laidOut) {
    offsets.push(running);
    running += heightOf(item.id) + GAP;
  }

  const stopFrame = (id: string) => {
    const frame = frames.current.get(id);
    if (frame !== undefined) {
      cancelAnimationFrame(frame);
      frames.current.delete(id);
    }
  };

  const paint = (id: string, x: number) => {
    swipeX.current.set(id, x);
    const node = swipeRefs.current.get(id);
    if (node) {
      node.style.transition = "none";
      node.style.transform = x === 0 ? "" : `translateX(${x}px)`;
      node.style.opacity = x === 0 ? "" : `${opacityFor(x)}`;
    }
  };

  /** Step a per-card simulation on rAF until it reports it is done. */
  const run = (
    id: string,
    step: (dt: number) => boolean,
    onDone?: () => void
  ) => {
    stopFrame(id);
    let last = performance.now();
    const tick = (now: number) => {
      // Clamp the step so a dropped frame or a background tab can't fling
      // the simulation.
      const dt = Math.min((now - last) / 1000, 1 / 30);
      last = now;
      if (step(dt)) {
        frames.current.delete(id);
        onDone?.();
        return;
      }
      frames.current.set(id, requestAnimationFrame(tick));
    };
    frames.current.set(id, requestAnimationFrame(tick));
  };

  /** Spring back to rest, starting with the speed the finger let go at. */
  const snapBack = (id: string, velocity: number) => {
    let x = swipeX.current.get(id) ?? 0;
    let v = velocity * 1000;
    if (prefersReducedMotion()) {
      paint(id, 0);
      return;
    }
    run(id, (dt) => {
      const force = -SPRING_STIFFNESS * x - SPRING_DAMPING * v;
      v += force * dt;
      x += v * dt;
      if (Math.abs(x) < 0.5 && Math.abs(v) < 10) {
        paint(id, 0);
        return true;
      }
      paint(id, x);
      return false;
    });
  };

  const finishDismiss = (id: string) => {
    setItems((prev) => prev.filter((item) => item.id !== id));
    lastY.current.delete(id);
    swipeX.current.delete(id);
    setLeaving((prev) => {
      const next = new Set(prev);
      next.delete(id);
      return next;
    });
    onDismiss?.(id);
  };

  /**
   * Throw the card off the side. A swipe keeps the speed it was released
   * at (so a hard flick leaves faster than a slow drag past the threshold);
   * a button or keyboard dismiss starts from rest at the minimum speed.
   */
  const dismiss = (id: string, direction: 1 | -1, velocity = 0) => {
    if (dismissed.current.has(id)) {
      return;
    }
    dismissed.current.add(id);
    setLeaving((prev) => new Set(prev).add(id));
    const node = swipeRefs.current.get(id);

    // Keyboard and button dismissals keep focus in the stack: it moves to
    // the next card (or the previous one, or the list once it is empty)
    // instead of dropping to the page when this card unmounts.
    if (node?.contains(document.activeElement)) {
      const at = laidOut.findIndex((item) => item.id === id);
      const next = laidOut[at + 1] ?? laidOut[at - 1];
      const target = next
        ? swipeRefs.current.get(next.id)?.querySelector("article")
        : listRef.current;
      target?.focus();
    }

    if (!node || prefersReducedMotion()) {
      stopFrame(id);
      if (node) {
        node.style.transition = `opacity ${EXIT_MS}ms ${EASE_OUT}`;
        node.style.opacity = "0";
      }
      const timer = window.setTimeout(() => finishDismiss(id), EXIT_MS);
      timers.current.push(timer);
      return;
    }

    const distance = node.offsetWidth * 1.1;
    let x = swipeX.current.get(id) ?? 0;
    let speed = Math.max(Math.abs(velocity) * 1000, FLIGHT_MIN_SPEED);
    run(
      id,
      (dt) => {
        speed += FLIGHT_ACCEL * dt;
        x += direction * speed * dt;
        const done = Math.abs(x) >= distance;
        paint(id, done ? direction * distance : x);
        node.style.opacity = `${Math.max(1 - Math.abs(x) / distance, 0)}`;
        return done;
      },
      () => finishDismiss(id)
    );
  };

  const handlePointerDown = (
    event: PointerEvent<HTMLDivElement>,
    index: number,
    id: string
  ) => {
    // Only the front card can be swiped while the stack is collapsed, and a
    // second finger never takes over a drag that is already running.
    if (drag.current || leaving.has(id) || (!expanded && index > 0)) {
      return;
    }
    suppressClick.current = false;
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    if ((event.target as HTMLElement).closest("button")) {
      return;
    }
    // Catch a card that is still springing back from the last swipe.
    stopFrame(id);
    const { pointerId } = event;
    const release = (up: globalThis.PointerEvent) => {
      if (up.pointerId !== pointerId) {
        return;
      }
      stopListening.current?.();
      // The card's own handlers run first; this only clears a gesture that
      // ended off the card, which would otherwise block the next one.
      if (drag.current?.pointerId === pointerId) {
        drag.current = null;
        if (swipeX.current.get(id)) {
          snapBack(id, 0);
        }
      }
    };
    stopListening.current?.();
    window.addEventListener("pointerup", release);
    window.addEventListener("pointercancel", release);
    stopListening.current = () => {
      window.removeEventListener("pointerup", release);
      window.removeEventListener("pointercancel", release);
      stopListening.current = null;
    };
    drag.current = {
      pointerId: event.pointerId,
      startX: event.clientX,
      startY: event.clientY,
      originX: swipeX.current.get(id) ?? 0,
      dx: 0,
      axis: null,
      samples: [],
    };
  };

  const handlePointerMove = (
    event: PointerEvent<HTMLDivElement>,
    id: string
  ) => {
    const current = drag.current;
    if (!current || current.pointerId !== event.pointerId) {
      return;
    }
    const dx = event.clientX - current.startX;
    const dy = event.clientY - current.startY;

    if (current.axis === null) {
      if (Math.abs(dx) < AXIS_LOCK && Math.abs(dy) < AXIS_LOCK) {
        return;
      }
      current.axis = Math.abs(dx) > Math.abs(dy) ? "x" : "y";
      if (current.axis === "x") {
        // Keep the swipe alive when the pointer leaves the card.
        event.currentTarget.setPointerCapture(event.pointerId);
      }
    }
    if (current.axis !== "x") {
      return;
    }

    current.dx = current.originX + dx;
    current.samples.push({ t: event.timeStamp, x: current.dx });
    if (current.samples.length > 12) {
      current.samples.shift();
    }
    // Written straight to the element: no re-render per pointer move.
    paint(id, current.dx);
  };

  const handlePointerUp = (event: PointerEvent<HTMLDivElement>, id: string) => {
    const current = drag.current;
    if (!current || current.pointerId !== event.pointerId) {
      return;
    }
    drag.current = null;
    if (current.axis !== "x") {
      // A tap or scroll that caught a card mid spring lets it finish.
      if (swipeX.current.get(id)) {
        snapBack(id, 0);
      }
      return;
    }
    suppressClick.current = true;

    const velocity = releaseVelocity(current.samples);
    const direction = dismissDirection(current.dx, velocity);
    if (direction === 0) {
      snapBack(id, velocity);
      return;
    }
    // Never carry speed that points back toward the stack into the flight.
    dismiss(id, direction, Math.sign(velocity) === direction ? velocity : 0);
  };

  const handleCardKeyDown = (event: KeyboardEvent<HTMLElement>, id: string) => {
    if (event.key === "Delete" || event.key === "Backspace") {
      event.preventDefault();
      // A held key would clear the next card too, now that focus moves to it.
      if (event.repeat) {
        return;
      }
      dismiss(id, 1);
    }
  };

  return (
    // biome-ignore lint/a11y: hover and focus only widen the stack; every action has its own button.
    <div
      className={cn("w-full max-w-sm", className)}
      onBlur={(event) => {
        if (!event.currentTarget.contains(event.relatedTarget as Node)) {
          setFocused(false);
        }
      }}
      onFocus={() => setFocused(true)}
      onPointerEnter={(event) => {
        // Touch screens fire pointerenter on tap; only a real hover expands.
        if (event.pointerType === "mouse") {
          setHovered(true);
        }
      }}
      onPointerLeave={(event) => {
        if (event.pointerType === "mouse") {
          setHovered(false);
        }
      }}
    >
      <div className="mb-3 flex h-7 items-center justify-between px-1">
        <p className="font-medium text-sm text-zinc-900 dark:text-zinc-100">
          Notifications
          <span className="ml-2 text-zinc-500 tabular-nums dark:text-zinc-400">
            {laidOut.length}
          </span>
        </p>
        {laidOut.length > 1 && (
          <button
            aria-expanded={expanded}
            className="rounded-md px-2 py-1 text-sm text-zinc-500 transition-colors duration-150 hover:bg-zinc-100 hover:text-zinc-900 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 dark:text-zinc-400 dark:hover:bg-zinc-800 dark:hover:text-zinc-100"
            onClick={() => setPinned((prev) => !prev)}
            type="button"
          >
            {expanded ? "Show less" : "Show all"}
          </button>
        )}
      </div>

      <ol
        aria-label="Notifications"
        className="relative outline-none transition-[height] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none"
        ref={listRef}
        style={{ height: stackHeight }}
        // Focus lands here when the last card is dismissed from the keyboard.
        tabIndex={-1}
      >
        {items.map((item) => {
          const index = laidOut.findIndex((card) => card.id === item.id);
          const isLeaving = index === -1;
          const depth = Math.max(index, 0);
          const hiddenBehind = !(expanded || depth <= VISIBLE_BEHIND);
          const scale = expanded || isLeaving ? 1 : 1 - depth * 0.05;
          // Bottom-align the cards behind so a strip of each peeks out below
          // the front card, whatever their own heights.
          const restingY = expanded
            ? offsets[depth]
            : frontHeight + depth * PEEK - heightOf(item.id) * scale;
          const y = isLeaving ? (lastY.current.get(item.id) ?? 0) : restingY;
          if (!isLeaving) {
            lastY.current.set(item.id, restingY);
          }

          return (
            <li
              className="absolute inset-x-0 top-0 origin-top transition-[transform,opacity] duration-300 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-opacity"
              data-id={item.id}
              key={item.id}
              style={{
                transform: `translateY(${y}px) scale(${scale})`,
                opacity: hiddenBehind ? 0 : 1,
                zIndex: items.length - depth,
                pointerEvents: hiddenBehind ? "none" : undefined,
              }}
            >
              <div
                className="touch-pan-y"
                onLostPointerCapture={(event) => {
                  // Touch starts with an implicit capture on the element
                  // under the finger; moving it to this card fires a
                  // bubbling lostpointercapture that is not the end of the
                  // swipe.
                  if (event.target === event.currentTarget) {
                    handlePointerUp(event, item.id);
                  }
                }}
                onPointerCancel={(event) => handlePointerUp(event, item.id)}
                onPointerDown={(event) =>
                  handlePointerDown(event, depth, item.id)
                }
                onPointerMove={(event) => handlePointerMove(event, item.id)}
                onPointerUp={(event) => handlePointerUp(event, item.id)}
                ref={(node) => {
                  if (node) {
                    swipeRefs.current.set(item.id, node);
                  } else {
                    swipeRefs.current.delete(item.id);
                  }
                }}
              >
                {/* biome-ignore lint/a11y: the card is focusable so Delete can dismiss it, and tapping it fans out the stack; both also have buttons. */}
                <article
                  aria-label={`${item.app}: ${item.title}. ${item.body}`}
                  className={cn(
                    "group/card relative flex select-none gap-3 rounded-2xl border border-zinc-200 bg-white p-3.5 shadow-sm outline-none dark:border-zinc-800 dark:bg-zinc-900",
                    "focus-visible:ring-2 focus-visible:ring-zinc-400",
                    !expanded &&
                      depth === 0 &&
                      laidOut.length > 1 &&
                      "cursor-pointer"
                  )}
                  onClick={() => {
                    if (suppressClick.current) {
                      suppressClick.current = false;
                      return;
                    }
                    if (!expanded) {
                      setPinned(true);
                    }
                  }}
                  onKeyDown={(event) => handleCardKeyDown(event, item.id)}
                  tabIndex={hiddenBehind ? -1 : 0}
                >
                  <NotificationContent
                    item={item}
                    muted={!expanded && depth > 0}
                    onDismiss={() => dismiss(item.id, 1)}
                    tabbable={!hiddenBehind}
                  />
                </article>
              </div>
            </li>
          );
        })}
      </ol>

      {laidOut.length === 0 && (
        <p className="py-6 text-center text-sm text-zinc-500 dark:text-zinc-400">
          You're all caught up.
        </p>
      )}
    </div>
  );
}

function NotificationContent({
  item,
  muted,
  tabbable,
  onDismiss,
}: {
  item: StackNotification;
  /** Cards behind the front one show only their edge, so their content
   * fades out instead of poking through. */
  muted: boolean;
  tabbable: boolean;
  onDismiss: () => void;
}) {
  return (
    <>
      <div
        className={cn(
          "flex min-w-0 flex-1 gap-3 transition-opacity duration-200",
          muted && "opacity-0"
        )}
      >
        <div className="shrink-0">{item.icon}</div>
        <div className="min-w-0 flex-1">
          <div className="flex items-baseline justify-between gap-2">
            <p className="truncate font-medium text-sm text-zinc-900 dark:text-zinc-100">
              {item.title}
            </p>
            <span className="shrink-0 text-xs text-zinc-400 tabular-nums">
              {item.time}
            </span>
          </div>
          <p className="line-clamp-2 text-sm text-zinc-500 dark:text-zinc-400">
            {item.body}
          </p>
        </div>
      </div>
      <button
        aria-label={`Dismiss ${item.title}`}
        className={cn(
          "absolute -top-2 -left-2 flex size-6 items-center justify-center rounded-full border border-zinc-200 bg-white text-zinc-500 opacity-0 transition-opacity duration-150 hover:text-zinc-900 focus-visible:opacity-100 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 group-hover/card:opacity-100 dark:border-zinc-700 dark:bg-zinc-800 dark:text-zinc-400 dark:hover:text-zinc-100",
          muted && "hidden"
        )}
        onClick={(event) => {
          event.stopPropagation();
          onDismiss();
        }}
        tabIndex={tabbable ? 0 : -1}
        type="button"
      >
        <X className="size-3" />
      </button>
    </>
  );
}
```


---

# Receipt Printer
> A receipt that prints line by line, then tears off and falls when you pull it, built with React.

Source: https://kokonutui.com/docs/cards/receipt-printer

## Installation

```bash
npx shadcn@latest add @kokonutui/receipt-printer
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Receipt Printer
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type PointerEvent,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// Where the paper comes out, from the top of the card.
const SLOT_Y = 64;
// The printer feeds a line at a time, with a short stop between lines.
const LINE = 15;
const FEED_RATE = 34;
const LINE_PAUSE = 0.055;
const LINE_JITTER = 0.05;
// Simulation, in px and seconds, on a fixed step.
const STEP = 1 / 120;
const GRAVITY = 2600;
const DAMPING = 0.996;
// While hanging from the slot, a pull stretches only this far, with
// growing resistance, and tears past this much drag.
const MAX_PULL = 18;
const TEAR_DRAG = 72;
// A sharp downward yank tears it too, in px per second.
const TEAR_SPEED = 900;
// A tilted sheet glides sideways as it falls.
const GLIDE = 0.35;
const REST_EPSILON = 0.02;

type Phase = "idle" | "printing" | "hanging" | "held" | "falling";

export interface ReceiptItem {
  name: string;
  quantity: number;
  price: number;
}

export interface ReceiptPrinterProps {
  merchant?: string;
  order?: string;
  date?: string;
  items?: ReceiptItem[];
  /** Tax rate, 0.08 for 8%. */
  tax?: number;
  currency?: string;
  /** Print as soon as the printer scrolls into view. */
  autoPrint?: boolean;
  onPrint?: () => void;
  onTear?: () => void;
  className?: string;
}

const DEFAULT_ITEMS: ReceiptItem[] = [
  { name: "Flat white", quantity: 2, price: 4.5 },
  { name: "Almond croissant", quantity: 1, price: 3.8 },
  { name: "Oat milk", quantity: 2, price: 0.6 },
  { name: "Banana bread", quantity: 1, price: 3.2 },
];

// Barcode bar widths, fixed so server and browser agree.
const BARS = [
  2, 1, 1, 3, 1, 2, 2, 1, 3, 1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 3, 2, 1, 1, 2, 1,
  3, 1, 1, 2, 2, 1, 1, 3, 1, 2,
];

function damp(distance: number, max: number) {
  return max * (1 - Math.exp(-distance / max));
}

function haptic(ms = 8) {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(ms);
  }
}

/** Local point p on a sheet turned by `angle`, relative to its corner. */
function turn(px: number, py: number, angle: number) {
  const cos = Math.cos(angle);
  const sin = Math.sin(angle);
  return [px * cos - py * sin, px * sin + py * cos];
}

function Receipt({
  merchant,
  order,
  date,
  items,
  tax,
  currency,
}: Required<
  Pick<
    ReceiptPrinterProps,
    "merchant" | "order" | "date" | "items" | "tax" | "currency"
  >
>) {
  const money = (n: number) => n.toFixed(2);
  const subtotal = items.reduce((sum, i) => sum + i.quantity * i.price, 0);
  const taxAmount = subtotal * tax;
  return (
    <div className="px-5 pt-6 pb-8 font-mono text-[11px] text-zinc-800 leading-[15px]">
      <p className="text-center font-semibold text-xs tracking-[0.2em]">
        {merchant.toUpperCase()}
      </p>
      <p className="text-center text-zinc-500">{date}</p>
      <p className="text-center text-zinc-500">Order {order}</p>
      <p
        aria-hidden="true"
        className="my-[7px] overflow-hidden whitespace-nowrap text-zinc-400"
      >
        {"- ".repeat(40)}
      </p>
      {items.map((item) => (
        <p className="flex justify-between gap-3" key={item.name}>
          <span className="truncate">
            {item.quantity} × {item.name}
          </span>
          <span className="tabular-nums">
            {money(item.quantity * item.price)}
          </span>
        </p>
      ))}
      <p
        aria-hidden="true"
        className="my-[7px] overflow-hidden whitespace-nowrap text-zinc-400"
      >
        {"- ".repeat(40)}
      </p>
      <p className="flex justify-between text-zinc-500">
        <span>Subtotal</span>
        <span className="tabular-nums">{money(subtotal)}</span>
      </p>
      <p className="flex justify-between text-zinc-500">
        <span>Tax {Math.round(tax * 100)}%</span>
        <span className="tabular-nums">{money(taxAmount)}</span>
      </p>
      <p className="mt-1 flex justify-between font-semibold text-[13px]">
        <span>Total</span>
        <span className="tabular-nums">
          {currency}
          {money(subtotal + taxAmount)}
        </span>
      </p>
      <div aria-hidden="true" className="mt-4 flex h-9 justify-center gap-px">
        {BARS.map((width, i) => (
          <span
            className={i % 2 ? "bg-transparent" : "bg-zinc-800"}
            key={`bar-${i.toString()}`}
            style={{ width }}
          />
        ))}
      </div>
      <p className="mt-3 text-center text-zinc-500">Thank you, come again</p>
    </div>
  );
}

// Serrated edges: the bottom was torn off the last receipt, and the top
// gets the same edge once this one is torn.
const TOOTH = 8;
const edge = (side: "top" | "bottom") =>
  `conic-gradient(from ${side === "bottom" ? "-45deg at 50% 100%" : "135deg at 50% 0"}, #0000, #000 1deg 89deg, #0000 90deg) 50% ${side === "bottom" ? "100%" : "0"} / ${TOOTH}px ${TOOTH / 2}px repeat-x`;
const FILL = `linear-gradient(#000 0 0) 0 ${TOOTH / 2}px / 100% calc(100% - ${TOOTH}px) no-repeat`;
const MASK_RESTING = `${edge("bottom")}, linear-gradient(#000 0 0) 0 0 / 100% calc(100% - ${TOOTH / 2}px) no-repeat`;
const MASK_TORN = `${edge("top")}, ${edge("bottom")}, ${FILL}`;

export default function ReceiptPrinter({
  merchant = "Kokonut Coffee",
  order = "#4182",
  date = "14 Oct 2026 · 08:42",
  items = DEFAULT_ITEMS,
  tax = 0.08,
  currency = "$",
  autoPrint = true,
  onPrint,
  onTear,
  className,
}: ReceiptPrinterProps) {
  const [phase, setPhase] = useState<Phase>("idle");
  const [torn, setTorn] = useState(false);

  const cardRef = useRef<HTMLDivElement>(null);
  const paperRef = useRef<HTMLDivElement>(null);
  const printerRef = useRef<HTMLDivElement>(null);

  const sim = useRef({
    phase: "idle" as Phase,
    width: 0,
    height: 0,
    slotX: 0,
    // Centre of mass, now and one step ago (Verlet), and the sheet's angle.
    cx: 0,
    cy: 0,
    pcx: 0,
    pcy: 0,
    angle: 0,
    spin: 0,
    // The hinge: a world point the sheet hangs from, and where on the
    // sheet it is.
    hx: 0,
    hy: 0,
    hingeX: 0,
    hingeY: 0,
    // Printing: how much paper is still inside the printer.
    hidden: 0,
    feedTarget: 0,
    pause: 0,
    // Dragging.
    pointerId: -1,
    grabX: 0,
    grabY: 0,
    startX: 0,
    startY: 0,
    samples: [] as { t: number; x: number; y: number }[],
    raf: 0,
    last: 0,
    carry: 0,
    visible: false,
    reduceMotion: false,
  });

  const callbacks = useRef({ onPrint, onTear });
  callbacks.current = { onPrint, onTear };

  const setPhaseBoth = useCallback((next: Phase) => {
    sim.current.phase = next;
    setPhase(next);
  }, []);

  const draw = useCallback(() => {
    const s = sim.current;
    const paper = paperRef.current;
    if (!paper) {
      return;
    }
    // Place the sheet so its centre of mass lands on (cx, cy), turned by
    // `angle` around its top-left corner.
    const [ox, oy] = turn(s.width / 2, s.height / 2, s.angle);
    const left = s.slotX - s.width / 2;
    const tx = s.cx - ox - left;
    const ty = s.cy - oy - SLOT_Y;
    paper.style.transform = `translate3d(${tx.toFixed(2)}px,${ty.toFixed(2)}px,0) rotate(${s.angle.toFixed(4)}rad)`;
  }, []);

  // The centre of mass for a sheet hanging from the hinge at `angle`.
  const hangAt = useCallback((angle: number) => {
    const s = sim.current;
    const [dx, dy] = turn(
      s.width / 2 - s.hingeX,
      s.height / 2 - s.hingeY,
      angle
    );
    return [s.hx + dx, s.hy + dy];
  }, []);

  const placeAtSlot = useCallback(
    (pull: number) => {
      const s = sim.current;
      s.hingeX = s.width / 2;
      s.hingeY = 0;
      s.hx = s.slotX;
      s.hy = SLOT_Y + pull;
      const [cx, cy] = hangAt(0);
      s.cx = cx;
      s.cy = cy;
      s.pcx = cx;
      s.pcy = cy;
      s.angle = 0;
    },
    [hangAt]
  );

  // A thermal printer moves in short bursts: feed a line, stop, feed.
  const stepPrinting = useCallback(
    (dt: number) => {
      const s = sim.current;
      if (s.pause > 0) {
        s.pause -= dt;
      } else if (s.feedTarget > 0) {
        s.feedTarget = Math.max(0, s.feedTarget - LINE);
        s.pause = LINE_PAUSE + Math.random() * LINE_JITTER;
      }
      s.hidden += (s.feedTarget - s.hidden) * Math.min(1, FEED_RATE * dt);
      if (Math.abs(s.hidden - s.feedTarget) < 0.05) {
        s.hidden = s.feedTarget;
      }
      placeAtSlot(-s.hidden);
      const printer = printerRef.current;
      if (printer) {
        // The housing buzzes while the motor runs.
        const buzz = s.pause > 0 ? 0 : Math.sin(performance.now() / 9) * 0.4;
        printer.style.transform = `translate3d(${buzz.toFixed(2)}px,0,0)`;
      }
      if (s.hidden === 0 && s.feedTarget === 0) {
        if (printer) {
          printer.style.transform = "";
        }
        setPhaseBoth("hanging");
        return 0;
      }
      return 1;
    },
    [placeAtSlot, setPhaseBoth]
  );

  // Hanging from a hinge: the centre of mass swings on a fixed-length
  // rod, and the sheet turns with it.
  const stepPendulum = useCallback(() => {
    const s = sim.current;
    const vx = (s.cx - s.pcx) * DAMPING;
    const vy = (s.cy - s.pcy) * DAMPING;
    s.pcx = s.cx;
    s.pcy = s.cy;
    s.cx += vx;
    s.cy += vy + GRAVITY * STEP * STEP;
    const rod = Math.hypot(s.width / 2 - s.hingeX, s.height / 2 - s.hingeY);
    const dx = s.cx - s.hx;
    const dy = s.cy - s.hy;
    const dist = Math.hypot(dx, dy) || 1;
    s.cx = s.hx + (dx / dist) * rod;
    s.cy = s.hy + (dy / dist) * rod;
    const rest = Math.atan2(s.height / 2 - s.hingeY, s.width / 2 - s.hingeX);
    s.angle = Math.atan2(s.cy - s.hy, s.cx - s.hx) - rest;
    return Math.abs(vx) + Math.abs(vy);
  }, []);

  // Free fall: gravity, a little air, and a tilted sheet drifts sideways.
  const stepFalling = useCallback(() => {
    const s = sim.current;
    let vx = (s.cx - s.pcx) * DAMPING;
    const vy = (s.cy - s.pcy) * DAMPING;
    vx += Math.sin(s.angle) * Math.max(vy, 0) * GLIDE * STEP * 10;
    s.pcx = s.cx;
    s.pcy = s.cy;
    s.cx += vx;
    s.cy += vy + GRAVITY * STEP * STEP;
    s.angle += s.spin * STEP;
    s.spin *= 0.995;
    // Off the bottom of the card: done.
    const card = cardRef.current;
    const floor =
      (card?.clientHeight ?? 400) + Math.hypot(s.width, s.height) / 2;
    return s.cy > floor ? 0 : 1;
  }, []);

  const stepPhysics = useCallback(
    (elapsed: number) => {
      const s = sim.current;
      let busy = 0;
      s.carry += elapsed;
      while (s.carry >= STEP) {
        s.carry -= STEP;
        if (s.phase === "falling") {
          busy = stepFalling();
        } else if (s.phase === "hanging" || s.phase === "held") {
          busy = stepPendulum();
        }
      }
      return busy;
    },
    [stepFalling, stepPendulum]
  );

  const finishFall = useCallback(() => {
    setPhaseBoth("idle");
  }, [setPhaseBoth]);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      const busy =
        s.phase === "printing" ? stepPrinting(elapsed) : stepPhysics(elapsed);
      draw();
      if (s.phase === "falling" && busy === 0) {
        finishFall();
        s.last = 0;
        return;
      }
      const keepGoing =
        s.phase === "printing" ||
        s.phase === "falling" ||
        s.pointerId >= 0 ||
        busy > REST_EPSILON;
      if (keepGoing && s.visible) {
        s.raf = requestAnimationFrame(tick);
      } else {
        s.last = 0;
      }
    },
    [draw, finishFall, stepPhysics, stepPrinting]
  );

  const wake = useCallback(() => {
    const s = sim.current;
    if (!s.raf && s.visible) {
      s.raf = requestAnimationFrame(tick);
    }
  }, [tick]);

  const measure = useCallback(() => {
    const s = sim.current;
    const card = cardRef.current;
    const paper = paperRef.current;
    if (!(card && paper)) {
      return;
    }
    s.width = paper.offsetWidth;
    s.height = paper.offsetHeight;
    s.slotX = card.clientWidth / 2;
  }, []);

  const print = useCallback(() => {
    const s = sim.current;
    measure();
    setTorn(false);
    callbacks.current.onPrint?.();
    if (s.reduceMotion) {
      placeAtSlot(0);
      draw();
      setPhaseBoth("hanging");
      return;
    }
    s.hidden = s.height;
    s.feedTarget = s.height;
    s.pause = 0.25;
    placeAtSlot(-s.hidden);
    draw();
    setPhaseBoth("printing");
    wake();
  }, [draw, measure, placeAtSlot, setPhaseBoth, wake]);

  const tear = useCallback(
    (held: boolean) => {
      const s = sim.current;
      setTorn(true);
      haptic(14);
      callbacks.current.onTear?.();
      const printer = printerRef.current;
      printer?.animate(
        [
          { transform: "translate3d(0,1.5px,0)" },
          { transform: "translate3d(0,0,0)" },
        ],
        { duration: 220, easing: "cubic-bezier(0.23, 1, 0.32, 1)" }
      );
      if (s.reduceMotion) {
        setPhaseBoth("idle");
        return;
      }
      setPhaseBoth(held ? "held" : "falling");
      wake();
    },
    [setPhaseBoth, wake]
  );

  // Print once it scrolls into view; pause the loop when it's offscreen.
  useEffect(() => {
    const s = sim.current;
    const card = cardRef.current;
    if (!card) {
      return;
    }
    s.reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    measure();
    placeAtSlot(-s.height);
    draw();
    let printed = false;
    let onScreen = false;
    const update = () => {
      s.visible = onScreen && !document.hidden;
      if (!s.visible) {
        cancelAnimationFrame(s.raf);
        s.raf = 0;
        s.last = 0;
        return;
      }
      if (autoPrint && !printed) {
        printed = true;
        print();
      }
      wake();
    };
    const intersection = new IntersectionObserver(
      ([entry]) => {
        onScreen = entry.isIntersecting;
        update();
      },
      { threshold: 0.4 }
    );
    intersection.observe(card);
    document.addEventListener("visibilitychange", update);
    return () => {
      intersection.disconnect();
      document.removeEventListener("visibilitychange", update);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, [autoPrint, draw, measure, placeAtSlot, print, wake]);

  const localPoint = (event: PointerEvent) => {
    const rect = cardRef.current?.getBoundingClientRect();
    return rect
      ? { x: event.clientX - rect.left, y: event.clientY - rect.top }
      : { x: 0, y: 0 };
  };

  // A world point to where it sits on the sheet.
  const toSheet = (x: number, y: number) => {
    const s = sim.current;
    const [ox, oy] = turn(s.width / 2, s.height / 2, s.angle);
    const cornerX = s.cx - ox;
    const cornerY = s.cy - oy;
    return turn(x - cornerX, y - cornerY, -s.angle);
  };

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    if (
      s.phase !== "hanging" ||
      (event.pointerType === "mouse" && event.button !== 0)
    ) {
      return;
    }
    const { x, y } = localPoint(event);
    event.currentTarget.setPointerCapture(event.pointerId);
    s.pointerId = event.pointerId;
    s.startX = x;
    s.startY = y;
    const [gx, gy] = toSheet(x, y);
    s.grabX = gx;
    s.grabY = gy;
    s.samples = [{ t: event.timeStamp, x, y }];
    wake();
  };

  // Still attached: the sheet turns about the slot so the grabbed point
  // follows the hand sideways, and stretches a little downward.
  const dragAttached = (x: number, y: number) => {
    const s = sim.current;
    const pull = damp(Math.max(0, y - s.startY), MAX_PULL);
    s.hingeX = s.width / 2;
    s.hingeY = 0;
    s.hx = s.slotX;
    s.hy = SLOT_Y + pull;
    const reach = Math.max(s.grabY, 24);
    const angle = -Math.atan2(x - s.slotX - (s.grabX - s.width / 2), reach);
    const [cx, cy] = hangAt(angle * 0.7);
    s.pcx = s.cx;
    s.pcy = s.cy;
    s.cx = cx;
    s.cy = cy;
    s.angle = angle * 0.7;
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    if (s.pointerId !== event.pointerId) {
      return;
    }
    const { x, y } = localPoint(event);
    s.samples.push({ t: event.timeStamp, x, y });
    if (s.samples.length > 5) {
      s.samples.shift();
    }
    if (s.phase === "hanging") {
      if (y - s.startY > TEAR_DRAG) {
        // It rips at the slot and stays in the hand, swinging from where
        // it was grabbed.
        s.hingeX = s.grabX;
        s.hingeY = s.grabY;
        s.hx = x;
        s.hy = y;
        tear(true);
      } else {
        dragAttached(x, y);
      }
    } else if (s.phase === "held") {
      s.hx = x;
      s.hy = y;
    }
    wake();
  };

  const releaseVelocity = () => {
    const s = sim.current;
    const first = s.samples[0];
    const last = s.samples.at(-1) ?? first;
    const dt = Math.max((last.t - first.t) / 1000, 0.016);
    return { vx: (last.x - first.x) / dt, vy: (last.y - first.y) / dt };
  };

  const handlePointerUp = (event: PointerEvent<HTMLDivElement>) => {
    const s = sim.current;
    if (s.pointerId !== event.pointerId) {
      return;
    }
    s.pointerId = -1;
    const { vx, vy } = releaseVelocity();
    if (s.phase === "held") {
      // Thrown: keep the hand's speed, and spin from the swing.
      const prevAngle = s.angle;
      stepPendulum();
      s.spin = (s.angle - prevAngle) / STEP + vx * 0.002;
      s.pcx = s.cx - vx * STEP * 0.6;
      s.pcy = s.cy - vy * STEP * 0.6;
      setPhaseBoth("falling");
    } else if (s.phase === "hanging" && vy > TEAR_SPEED) {
      // A sharp yank tears it straight off.
      s.pcx = s.cx - vx * STEP * 0.5;
      s.pcy = s.cy - vy * STEP * 0.5;
      s.spin = vx * 0.004;
      tear(false);
    } else if (s.phase === "hanging") {
      // Let go: it springs back up to the slot and the swing plays out.
      s.hy = SLOT_Y;
      s.pcx = s.cx;
      s.pcy = s.cy;
    }
    wake();
  };

  const handleTearKey = () => {
    const s = sim.current;
    if (s.phase === "hanging") {
      s.spin = 1.2;
      s.pcy = s.cy - 3;
      tear(false);
    }
  };

  const busy = phase === "printing";
  let status = "Ready";
  if (busy) {
    status = "Printing…";
  } else if (phase === "hanging") {
    status = "Pull down to tear";
  }

  return (
    <div
      className={cn(
        "relative h-[30rem] w-72 select-none overflow-hidden rounded-3xl border border-zinc-200 bg-zinc-50 text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      ref={cardRef}
    >
      {/* The sheet, clipped at the slot until it's torn free. */}
      <div
        className={cn(
          "absolute inset-x-0 bottom-0",
          torn ? "overflow-visible" : "overflow-hidden"
        )}
        style={{ top: SLOT_Y }}
      >
        <div
          aria-label={`Receipt from ${merchant}, order ${order}`}
          className={cn(
            "absolute top-0 w-56 bg-white shadow-[0_1px_2px_rgb(0_0_0/0.06),0_8px_24px_-12px_rgb(0_0_0/0.25)] outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 dark:bg-zinc-100",
            phase === "hanging" && "cursor-grab active:cursor-grabbing",
            phase === "held" && "cursor-grabbing",
            phase === "idle" && torn && "invisible"
          )}
          onLostPointerCapture={handlePointerUp}
          onPointerCancel={handlePointerUp}
          onPointerDown={handlePointerDown}
          onPointerMove={handlePointerMove}
          onPointerUp={handlePointerUp}
          ref={paperRef}
          role="document"
          style={{
            left: "50%",
            marginLeft: "-7rem",
            transformOrigin: "0 0",
            mask: torn ? MASK_TORN : MASK_RESTING,
            WebkitMask: torn ? MASK_TORN : MASK_RESTING,
            touchAction: "none",
          }}
        >
          <Receipt
            currency={currency}
            date={date}
            items={items}
            merchant={merchant}
            order={order}
            tax={tax}
          />
        </div>
      </div>

      {/* The printer housing, in front of the paper's top edge. */}
      <div
        className="absolute inset-x-0 top-0 h-16 border-zinc-200 border-b bg-white dark:border-zinc-800 dark:bg-zinc-900"
        ref={printerRef}
      >
        <div className="flex items-center justify-between px-5 pt-4 text-xs">
          <span className="font-medium">{merchant}</span>
          <span aria-live="polite" className="text-zinc-500 dark:text-zinc-400">
            {status}
          </span>
        </div>
        <div className="absolute inset-x-8 bottom-2 h-1 rounded-full bg-zinc-900 dark:bg-black" />
      </div>

      {phase === "hanging" && (
        <button
          className="sr-only focus:not-sr-only focus:absolute focus:right-4 focus:bottom-4 focus:rounded-full focus:bg-zinc-900 focus:px-3 focus:py-1.5 focus:text-white focus:text-xs dark:focus:bg-zinc-100 dark:focus:text-zinc-900"
          onClick={handleTearKey}
          type="button"
        >
          Tear off receipt
        </button>
      )}

      <div
        className={cn(
          "absolute inset-x-0 bottom-0 flex justify-center p-5 transition-opacity duration-200 ease-out",
          phase === "idle" ? "opacity-100" : "pointer-events-none opacity-0"
        )}
      >
        <button
          className="rounded-full bg-zinc-900 px-4 py-2 font-medium text-sm text-white outline-none transition-colors duration-150 ease-out hover:bg-zinc-700 focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 dark:bg-zinc-100 dark:text-zinc-900 dark:hover:bg-zinc-300"
          disabled={phase !== "idle"}
          onClick={print}
          tabIndex={phase === "idle" ? 0 : -1}
          type="button"
        >
          {torn ? "Print another" : "Print receipt"}
        </button>
      </div>
    </div>
  );
}
```


---

# Uptime Card
> A status page card with 90 days per service that swell under the cursor, and a day you click opens its incident log.

Source: https://kokonutui.com/docs/cards/uptime-card

## Installation

```bash
npx shadcn@latest add @kokonutui/uptime-card
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Uptime Card
 * @version: 1.0.0
 * @date: 2026-10-15
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { CircleCheck, TriangleAlert, X } from "lucide-react";
import {
  type KeyboardEvent,
  type PointerEvent,
  useCallback,
  useEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// How much wider the bar under the pointer gets, and how far the swell
// spreads, in bars.
const MAGNIFY = 5;
const SPREAD = 2.4;
// Bars ease toward their width at this rate, per second.
const EASE = 18;
const DAY = 86_400_000;

export type DayStatus = "up" | "degraded" | "down" | "none";

export interface IncidentUpdate {
  /** HH:MM, local to the status page. */
  time: string;
  label: string;
  note?: string;
}

export interface Incident {
  title: string;
  status: Exclude<DayStatus, "up" | "none">;
  /** Minutes of impact that day. */
  minutes: number;
  updates: IncidentUpdate[];
}

export interface UptimeService {
  name: string;
  /** Incidents by day index, 0 being the oldest day shown. */
  incidents?: Record<number, Incident>;
  /** Days with no data (before the service existed), from the start. */
  missing?: number;
}

export interface UptimeCardProps {
  title?: string;
  services?: UptimeService[];
  days?: number;
  /** The last day shown, as YYYY-MM-DD. */
  endDate?: string;
  className?: string;
}

const DEFAULT_SERVICES: UptimeService[] = [
  {
    name: "API",
    incidents: {
      19: {
        title: "Elevated error rates on writes",
        status: "degraded",
        minutes: 18,
        updates: [
          {
            time: "14:02",
            label: "Investigating",
            note: "5xx on POST rose to 2%.",
          },
          {
            time: "14:11",
            label: "Identified",
            note: "A bad config push to one region.",
          },
          {
            time: "14:20",
            label: "Resolved",
            note: "Rolled back; error rates normal.",
          },
        ],
      },
      84: {
        title: "Slow responses in eu-west",
        status: "degraded",
        minutes: 23,
        updates: [
          {
            time: "09:41",
            label: "Investigating",
            note: "p95 latency up 3x in eu-west.",
          },
          {
            time: "09:52",
            label: "Monitoring",
            note: "Added capacity to the pool.",
          },
          { time: "10:04", label: "Resolved" },
        ],
      },
    },
  },
  {
    name: "Dashboard",
    incidents: {
      43: {
        title: "Charts failed to load",
        status: "degraded",
        minutes: 12,
        updates: [
          { time: "18:30", label: "Investigating" },
          {
            time: "18:42",
            label: "Resolved",
            note: "A CDN cache rule was reverted.",
          },
        ],
      },
    },
  },
  {
    name: "Webhooks",
    incidents: {
      69: {
        title: "Deliveries delayed",
        status: "down",
        minutes: 48,
        updates: [
          {
            time: "02:15",
            label: "Investigating",
            note: "The delivery queue stopped draining.",
          },
          {
            time: "02:38",
            label: "Identified",
            note: "A worker deploy failed health checks.",
          },
          {
            time: "03:03",
            label: "Resolved",
            note: "Backlog delivered in order.",
          },
        ],
      },
    },
  },
  {
    name: "Database",
    missing: 6,
    incidents: {
      27: {
        title: "Failover to replica",
        status: "down",
        minutes: 9,
        updates: [
          {
            time: "22:07",
            label: "Investigating",
            note: "Primary stopped accepting writes.",
          },
          {
            time: "22:16",
            label: "Resolved",
            note: "Promoted the replica; no data lost.",
          },
        ],
      },
    },
  },
];

const clamp = (v: number, lo: number, hi: number) =>
  Math.min(hi, Math.max(lo, v));

const formatDay = (ms: number) =>
  new Date(ms).toLocaleDateString("en-US", {
    weekday: "short",
    month: "short",
    day: "numeric",
    timeZone: "UTC",
  });

function statusOf(service: UptimeService, day: number): DayStatus {
  if (day < (service.missing ?? 0)) {
    return "none";
  }
  return service.incidents?.[day]?.status ?? "up";
}

/** Downtime counts in full, degraded time at half. */
function uptimeOf(service: UptimeService, days: number) {
  const tracked = days - (service.missing ?? 0);
  let lost = 0;
  for (const incident of Object.values(service.incidents ?? {})) {
    lost += incident.minutes * (incident.status === "down" ? 1 : 0.5);
  }
  return 100 * (1 - lost / (tracked * 1440));
}

/** Target widths: a swell around the focus, flat without one. */
function swell(count: number, focus: number | null, out: Float64Array) {
  for (let i = 0; i < count; i++) {
    out[i] =
      focus === null
        ? 1
        : 1 + MAGNIFY * Math.exp(-(((i - focus) / SPREAD) ** 2));
  }
  return out;
}

/** The bar under x (0 to 1) when bars have these widths. */
function barAt(weights: Float64Array, x: number) {
  let total = 0;
  for (const w of weights) {
    total += w;
  }
  let at = x * total;
  for (let i = 0; i < weights.length; i++) {
    at -= weights[i];
    if (at <= 0) {
      return i;
    }
  }
  return weights.length - 1;
}

const BAR_COLOR: Record<DayStatus, string> = {
  up: "bg-emerald-500 dark:bg-emerald-400",
  degraded: "bg-amber-400 dark:bg-amber-300",
  down: "bg-rose-500 dark:bg-rose-400",
  none: "bg-zinc-200 dark:bg-zinc-800",
};

const STATUS_TEXT: Record<DayStatus, string> = {
  up: "Operational",
  degraded: "Degraded",
  down: "Outage",
  none: "No data",
};

export default function UptimeCard({
  title = "System status",
  services = DEFAULT_SERVICES,
  days = 90,
  endDate = "2026-10-14",
  className,
}: UptimeCardProps) {
  const [active, setActive] = useState<number | null>(null);
  const [pinned, setPinned] = useState<number | null>(null);
  const barsRef = useRef<HTMLDivElement>(null);
  const sim = useRef({
    weights: new Float64Array(days).fill(1),
    target: new Float64Array(days).fill(1),
    focus: null as number | null,
    raf: 0,
    last: 0,
    reduceMotion: false,
  });
  if (sim.current.weights.length !== days) {
    sim.current.weights = new Float64Array(days).fill(1);
    sim.current.target = new Float64Array(days).fill(1);
  }

  const end = Date.parse(`${endDate}T00:00:00Z`);
  const dateOf = useCallback(
    (day: number) => end - (days - 1 - day) * DAY,
    [end, days]
  );
  const uptimes = useMemo(
    () => services.map((s) => uptimeOf(s, days)),
    [services, days]
  );
  const openIssues = services.filter(
    (s) => statusOf(s, days - 1) !== "up" && statusOf(s, days - 1) !== "none"
  );

  // Widths are written straight to the bars, one flex-grow per bar.
  const paint = useCallback(() => {
    const rows = barsRef.current?.querySelectorAll<HTMLElement>("[data-row]");
    const { weights } = sim.current;
    for (const row of rows ?? []) {
      const bars = row.children;
      for (let i = 0; i < bars.length; i++) {
        (bars[i] as HTMLElement).style.flexGrow = weights[i].toFixed(3);
      }
    }
  }, []);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const dt = s.last ? Math.min((now - s.last) / 1000, 1 / 30) : 1 / 60;
      s.last = now;
      const k = 1 - Math.exp(-EASE * dt);
      let moving = false;
      for (let i = 0; i < s.weights.length; i++) {
        const gap = s.target[i] - s.weights[i];
        if (Math.abs(gap) > 0.002) {
          s.weights[i] += gap * k;
          moving = true;
        } else {
          s.weights[i] = s.target[i];
        }
      }
      paint();
      if (moving) {
        s.raf = requestAnimationFrame(tick);
      } else {
        s.last = 0;
      }
    },
    [paint]
  );

  const focusOn = useCallback(
    (focus: number | null) => {
      const s = sim.current;
      s.focus = focus;
      swell(s.weights.length, focus, s.target);
      if (s.reduceMotion) {
        s.weights.set(s.target);
        paint();
      } else if (!s.raf) {
        s.raf = requestAnimationFrame(tick);
      }
    },
    [paint, tick]
  );

  useEffect(() => {
    const s = sim.current;
    s.reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    return () => cancelAnimationFrame(s.raf);
  }, []);

  /** The day under the pointer, found against the swollen layout. */
  const dayAt = (clientX: number) => {
    const rect = barsRef.current?.getBoundingClientRect();
    if (!rect) {
      return 0;
    }
    const x = clamp((clientX - rect.left) / rect.width, 0, 1);
    const probe = new Float64Array(days);
    let day = Math.round(x * (days - 1));
    // Centre the swell on the bar that ends up under the pointer.
    for (let pass = 0; pass < 3; pass++) {
      day = barAt(swell(days, day, probe), x);
    }
    return day;
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    if (
      event.pointerType !== "mouse" &&
      !event.currentTarget.hasPointerCapture(event.pointerId)
    ) {
      return;
    }
    const day = dayAt(event.clientX);
    setActive(day);
    focusOn(day);
  };

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    if (event.pointerType !== "mouse") {
      event.currentTarget.setPointerCapture(event.pointerId);
    }
    const day = dayAt(event.clientX);
    setActive(day);
    focusOn(day);
  };

  const handleClick = () => {
    if (active !== null) {
      setPinned((p) => (p === active ? null : active));
    }
  };

  const leave = () => {
    setActive(null);
    focusOn(pinned);
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    const from = active ?? pinned ?? days - 1;
    const moves: Record<string, number> = {
      ArrowLeft: -1,
      ArrowRight: 1,
      Home: -days,
      End: days,
    };
    if (event.key === "Enter" || event.key === " ") {
      event.preventDefault();
      setPinned((p) => (p === from ? null : from));
      return;
    }
    if (event.key === "Escape") {
      setPinned(null);
      leave();
      return;
    }
    const move = moves[event.key];
    if (move === undefined) {
      return;
    }
    event.preventDefault();
    const day = clamp(from + move, 0, days - 1);
    setActive(day);
    focusOn(day);
  };

  const shownDay = active ?? pinned;
  const shownIncidents =
    shownDay === null
      ? []
      : services.flatMap((s) => {
          const incident = s.incidents?.[shownDay];
          return incident ? [{ service: s.name, incident }] : [];
        });
  let summary = "Hover a day to see what happened";
  if (shownDay !== null) {
    const first = shownIncidents[0];
    const what = first
      ? `${first.service} ${first.incident.status === "down" ? "down" : "degraded"} for ${first.incident.minutes} min${shownIncidents.length > 1 ? `, +${shownIncidents.length - 1} more` : ""}`
      : "No incidents";
    summary = `${formatDay(dateOf(shownDay))} · ${what}`;
  }
  const pinnedIncidents =
    pinned === null
      ? []
      : services.flatMap((s) => {
          const incident = s.incidents?.[pinned];
          return incident ? [{ service: s.name, incident }] : [];
        });

  return (
    <div
      className={cn(
        "w-full max-w-xl select-none rounded-3xl border border-zinc-200 bg-white p-5 text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
    >
      <div className="flex items-center justify-between gap-4">
        <p className="font-medium text-sm">{title}</p>
        {openIssues.length ? (
          <p className="flex items-center gap-1.5 text-amber-600 text-sm dark:text-amber-400">
            <TriangleAlert aria-hidden className="size-4" />
            {openIssues.length} service{openIssues.length > 1 ? "s" : ""}{" "}
            affected
          </p>
        ) : (
          <p className="flex items-center gap-1.5 text-emerald-600 text-sm dark:text-emerald-400">
            <CircleCheck aria-hidden className="size-4" />
            All systems operational
          </p>
        )}
      </div>
      <p
        aria-live="polite"
        className="mt-1 truncate text-sm text-zinc-500 tabular-nums dark:text-zinc-400"
      >
        {summary}
      </p>

      <div
        aria-label={`Daily status for the last ${days} days. Use the arrow keys to move between days and Enter to open one.`}
        aria-valuemax={days}
        aria-valuemin={1}
        aria-valuenow={(shownDay ?? days - 1) + 1}
        aria-valuetext={summary}
        className="mt-4 cursor-pointer touch-pan-y rounded-lg outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-4 dark:focus-visible:ring-offset-zinc-950"
        onClick={handleClick}
        onKeyDown={handleKeyDown}
        onLostPointerCapture={leave}
        onPointerDown={handlePointerDown}
        onPointerLeave={(event) => {
          if (event.pointerType === "mouse") {
            leave();
          }
        }}
        onPointerMove={handlePointerMove}
        ref={barsRef}
        role="slider"
        tabIndex={0}
      >
        {services.map((service, row) => (
          <div className={cn(row > 0 && "mt-3")} key={service.name}>
            <div className="mb-1.5 flex justify-between text-xs">
              <span className="font-medium">{service.name}</span>
              <span className="text-zinc-500 tabular-nums dark:text-zinc-400">
                {uptimes[row].toFixed(2)}%
              </span>
            </div>
            <div className="flex h-7 gap-px sm:gap-[2px]" data-row>
              {Array.from({ length: days }, (_, day) => {
                const status = statusOf(service, day);
                const lit = day === shownDay;
                return (
                  <div
                    className={cn(
                      "min-w-0 basis-0 rounded-[2px] transition-opacity duration-150 ease-out",
                      BAR_COLOR[status],
                      shownDay !== null && !lit && "opacity-60"
                    )}
                    // biome-ignore lint/suspicious/noArrayIndexKey: one bar per day, never reordered
                    key={day}
                    style={{ flexGrow: 1 }}
                  />
                );
              })}
            </div>
          </div>
        ))}
        <div className="mt-2 flex justify-between text-xs text-zinc-400 dark:text-zinc-500">
          <span>{days} days ago</span>
          <span>Today</span>
        </div>
      </div>

      {/* A pinned day opens its incident log. */}
      <div
        className={cn(
          "grid transition-[grid-template-rows,opacity] duration-[260ms] ease-[cubic-bezier(0.23,1,0.32,1)]",
          pinned === null
            ? "grid-rows-[0fr] opacity-0"
            : "grid-rows-[1fr] opacity-100"
        )}
      >
        <div className="overflow-hidden">
          {pinned !== null && (
            <div className="mt-4 rounded-2xl bg-zinc-50 p-4 dark:bg-zinc-900">
              <div className="flex items-center justify-between">
                <p className="font-medium text-sm">
                  {formatDay(dateOf(pinned))}
                </p>
                <button
                  aria-label="Close day"
                  className="rounded-full p-1 text-zinc-500 outline-none transition-colors duration-150 ease-out hover:bg-zinc-200 hover:text-zinc-900 focus-visible:ring-2 focus-visible:ring-zinc-400 dark:text-zinc-400 dark:hover:bg-zinc-800 dark:hover:text-zinc-100"
                  onClick={() => {
                    setPinned(null);
                    focusOn(null);
                  }}
                  type="button"
                >
                  <X aria-hidden className="size-3.5" />
                </button>
              </div>
              {pinnedIncidents.length === 0 && (
                <p className="mt-1 text-sm text-zinc-500 dark:text-zinc-400">
                  No incidents recorded. Every service was operational.
                </p>
              )}
              {pinnedIncidents.map(({ service, incident }) => (
                <div className="mt-3" key={service}>
                  <p className="flex flex-wrap items-center gap-2 text-sm">
                    <span
                      className={cn(
                        "rounded-full px-2 py-0.5 font-medium text-[11px]",
                        incident.status === "down"
                          ? "bg-rose-100 text-rose-700 dark:bg-rose-500/15 dark:text-rose-300"
                          : "bg-amber-100 text-amber-800 dark:bg-amber-400/15 dark:text-amber-200"
                      )}
                    >
                      {STATUS_TEXT[incident.status]}
                    </span>
                    <span className="font-medium">{service}</span>
                    <span className="text-zinc-500 dark:text-zinc-400">
                      {incident.title} · {incident.minutes} min
                    </span>
                  </p>
                  <ol className="mt-2.5 ml-1 border-zinc-200 border-l dark:border-zinc-800">
                    {incident.updates.map((update) => (
                      <li
                        className="relative pb-2.5 pl-4 text-sm last:pb-0"
                        key={`${update.time}-${update.label}`}
                      >
                        <span className="absolute top-[7px] -left-[3.5px] size-1.5 rounded-full bg-zinc-400 dark:bg-zinc-500" />
                        <span className="text-zinc-400 tabular-nums dark:text-zinc-500">
                          {update.time}
                        </span>{" "}
                        <span className="font-medium">{update.label}</span>
                        {update.note && (
                          <span className="text-zinc-500 dark:text-zinc-400">
                            {" "}
                            {update.note}
                          </span>
                        )}
                      </li>
                    ))}
                  </ol>
                </div>
              ))}
            </div>
          )}
        </div>
      </div>
    </div>
  );
}
```


---

# Command Palette
> ⌘K command palette with nested pages, fuzzy matching and in-row progress for running actions.

Source: https://kokonutui.com/docs/navigation/action-search-bar

## Installation

```bash
npx shadcn@latest add @kokonutui/action-search-bar
```

## Source

```tsx
"use client";

/**
 * @author: @kokonutui
 * @description: Command Palette with ⌘K, nested pages, fuzzy matching and in-row action progress
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  Activity,
  ArrowUpRight,
  BookOpen,
  Check,
  ChevronRight,
  Copy,
  FilePlus,
  FolderInput,
  History,
  Keyboard,
  Link2,
  LoaderCircle,
  Search,
  SunMoon,
  UserPlus,
} from "lucide-react";
import { animate, useReducedMotion } from "motion/react";
import {
  type ChangeEvent,
  type FocusEvent,
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface CommandItem {
  id: string;
  label: string;
  icon?: ReactNode;
  /** Section heading on its page, such as "Actions" or "Links". */
  group?: string;
  /** Extra words the row matches on, without being shown. */
  keywords?: string[];
  /** Keys shown at the end of the row, such as ["⌘", "N"]. */
  shortcut?: string[];
  /** Marks the row as a link. `onSelect` decides how to open it. */
  href?: string;
  /** Choosing the row opens these as a nested page instead of running it. */
  children?: CommandItem[];
  /** Input placeholder while this item's page is open. */
  placeholder?: string;
}

/** @deprecated Use `CommandItem`. */
export type Action = CommandItem;

export interface ActionSearchBarProps {
  items?: CommandItem[];
  /** Ids shown under "Recent" before anything is typed. Running a row adds it. */
  defaultRecent?: string[];
  /**
   * Called when a row without children is chosen. Return a Promise to show a
   * spinner in the row until it settles; a rejection leaves the palette open.
   */
  onSelect?: (item: CommandItem, path: CommandItem[]) => unknown;
  onOpenChange?: (open: boolean) => void;
  defaultOpen?: boolean;
  /**
   * ⌘K / Ctrl+K toggles the palette. By default it only does so while the
   * palette is focused or hovered, so the host page keeps its own ⌘K. Set
   * `true` to take ⌘K page-wide whenever the palette is on screen.
   */
  shortcut?: boolean;
  label?: string;
  placeholder?: string;
  className?: string;
}

interface Entry {
  item: CommandItem;
  /** Ancestors below the current page, shown as a "Parent ›" prefix. */
  path: CommandItem[];
}

interface Row extends Entry {
  key: string;
  matches: number[];
  score: number;
}

interface Section {
  key: string;
  label?: string;
  rows: Row[];
}

type InputSource = "keyboard" | "pointer";

const EASE_OUT = "cubic-bezier(0.23, 1, 0.32, 1)";
const HOLD_MS = 400;
const RECENT_LIMIT = 3;

const ICON = "size-4";

const sampleItems: CommandItem[] = [
  {
    id: "new-document",
    label: "New document",
    icon: <FilePlus className={ICON} />,
    group: "Actions",
    keywords: ["create", "page", "file"],
    shortcut: ["⌘", "N"],
  },
  {
    id: "duplicate",
    label: "Duplicate page",
    icon: <Copy className={ICON} />,
    group: "Actions",
    keywords: ["copy", "clone"],
    shortcut: ["⌘", "D"],
  },
  {
    id: "move",
    label: "Move to…",
    icon: <FolderInput className={ICON} />,
    group: "Actions",
    keywords: ["folder", "file"],
    placeholder: "Move to which folder?",
    children: [
      {
        id: "move-inbox",
        label: "Inbox",
        icon: <FolderInput className={ICON} />,
      },
      {
        id: "move-projects",
        label: "Projects",
        icon: <FolderInput className={ICON} />,
      },
      {
        id: "move-archive",
        label: "Archive",
        icon: <FolderInput className={ICON} />,
      },
    ],
  },
  {
    id: "theme",
    label: "Change theme",
    icon: <SunMoon className={ICON} />,
    group: "Actions",
    keywords: ["appearance", "dark", "light", "mode"],
    placeholder: "Choose a theme…",
    children: [
      { id: "theme-light", label: "Light", icon: <SunMoon className={ICON} /> },
      { id: "theme-dark", label: "Dark", icon: <SunMoon className={ICON} /> },
      {
        id: "theme-system",
        label: "Match system",
        icon: <SunMoon className={ICON} />,
      },
    ],
  },
  {
    id: "invite",
    label: "Invite member",
    icon: <UserPlus className={ICON} />,
    group: "Actions",
    keywords: ["team", "share", "add"],
  },
  {
    id: "copy-link",
    label: "Copy link",
    icon: <Link2 className={ICON} />,
    group: "Actions",
    keywords: ["url", "share"],
    shortcut: ["⌘", "L"],
  },
  {
    id: "docs",
    label: "Documentation",
    icon: <BookOpen className={ICON} />,
    group: "Links",
    keywords: ["help", "guide"],
    href: "/docs",
  },
  {
    id: "changelog",
    label: "Changelog",
    icon: <History className={ICON} />,
    group: "Links",
    keywords: ["release", "updates", "new"],
    href: "/changelog",
  },
  {
    id: "status",
    label: "Status page",
    icon: <Activity className={ICON} />,
    group: "Links",
    keywords: ["uptime", "incident"],
    href: "/status",
  },
  {
    id: "shortcuts",
    label: "Keyboard shortcuts",
    icon: <Keyboard className={ICON} />,
    group: "Links",
    keywords: ["keys", "hotkeys"],
    href: "/shortcuts",
  },
];

/* ---------------------------------------------------------------- matching */

const WORD_BREAK = /[\s\-_/.]/;
const WHITESPACE = /\s+/g;
const APPLE_PLATFORM = /mac|iphone|ipad/i;

const isWordStart = (text: string, i: number) =>
  i === 0 || WORD_BREAK.test(text[i - 1] ?? "");

/** The first word start at or after `from` that holds `ch`, else `from`. */
function nextWordStart(t: string, ch: string, from: number) {
  for (let j = from; j < t.length; j++) {
    if (t[j] === ch && isWordStart(t, j)) {
      return j;
    }
  }
  return from;
}

function subsequence(t: string, q: string, preferWordStarts: boolean) {
  const matches: number[] = [];
  let score = 0;
  let from = 0;
  for (const ch of q) {
    let i = t.indexOf(ch, from);
    if (i < 0) {
      return null;
    }
    const prev = matches.at(-1);
    // Unless it continues a run, jump ahead to a word start holding `ch`.
    if (preferWordStarts && (prev === undefined || i !== prev + 1)) {
      i = nextWordStart(t, ch, i);
    }
    score += prev !== undefined && i === prev + 1 ? 6 : 1;
    score += isWordStart(t, i) ? 8 : 0;
    score -= prev === undefined ? i * 0.5 : (i - prev - 1) * 0.2;
    matches.push(i);
    from = i + 1;
  }
  return { score, matches };
}

/**
 * Fuzzy match. Returns the matched character indices and a score that favours
 * contiguous runs, word starts and early matches; null when `query` is not a
 * subsequence of `text`.
 */
export function fuzzyMatch(
  text: string,
  query: string
): { score: number; matches: number[] } | null {
  const t = text.toLowerCase();
  const q = query.toLowerCase().replace(WHITESPACE, "");
  if (!q) {
    return { score: 0, matches: [] };
  }
  const at = t.indexOf(q);
  if (at >= 0) {
    const matches = Array.from({ length: q.length }, (_, k) => at + k);
    return { score: 100 - at + (isWordStart(t, at) ? 30 : 0), matches };
  }
  return subsequence(t, q, true) ?? subsequence(t, q, false);
}

function scoreEntry(entry: Entry, query: string) {
  const onLabel = fuzzyMatch(entry.item.label, query);
  if (onLabel) {
    return onLabel;
  }
  // Parent labels and keywords still find the row, ranked lower, unbolded.
  const extra = [
    ...entry.path.map((p) => p.label),
    ...(entry.item.keywords ?? []),
  ];
  let best: number | null = null;
  for (const word of extra) {
    const hit = fuzzyMatch(word, query);
    if (hit && (best === null || hit.score > best)) {
      best = hit.score;
    }
  }
  return best === null ? null : { score: best / 2, matches: [] };
}

/* ---------------------------------------------------------------- sections */

function flatten(items: CommandItem[], path: CommandItem[] = []): Entry[] {
  const out: Entry[] = [];
  for (const item of items) {
    out.push({ item, path });
    if (item.children) {
      out.push(...flatten(item.children, [...path, item]));
    }
  }
  return out;
}

function groupRows(rows: Row[], fallback?: string): Section[] {
  const byGroup = new Map<string, Row[]>();
  for (const row of rows) {
    const label = row.path[0]?.group ?? row.item.group ?? fallback ?? "";
    const list = byGroup.get(label) ?? [];
    list.push(row);
    byGroup.set(label, list);
  }
  return [...byGroup].map(([label, list]) => ({
    key: label || "items",
    label: label || undefined,
    rows: list,
  }));
}

function buildSections(
  page: CommandItem | undefined,
  rootItems: CommandItem[],
  query: string,
  recent: Entry[]
): Section[] {
  const items = page?.children ?? rootItems;
  const fallback = page?.label;

  if (!query.trim()) {
    const rows = items.map<Row>((item) => ({
      item,
      path: [],
      key: item.id,
      matches: [],
      score: 0,
    }));
    const sections = groupRows(rows, fallback);
    if (!page && recent.length > 0) {
      sections.unshift({
        key: "recent",
        label: "Recent",
        rows: recent.map((e) => ({
          ...e,
          key: `recent-${e.item.id}`,
          matches: [],
          score: 0,
        })),
      });
    }
    return sections;
  }

  // Searching from a page also reaches the rows nested inside it.
  const rows: Row[] = [];
  for (const entry of flatten(items)) {
    const hit = scoreEntry(entry, query);
    if (hit) {
      rows.push({ ...entry, key: entry.item.id, ...hit });
    }
  }
  const sections = groupRows(rows, fallback);
  for (const section of sections) {
    section.rows.sort((a, b) => b.score - a.score);
  }
  return sections;
}

function findEntry(items: CommandItem[], id: string): Entry | undefined {
  return flatten(items).find((e) => e.item.id === id);
}

/* ---------------------------------------------------------------- pieces */

function Highlighted({ text, matches }: { text: string; matches: number[] }) {
  if (matches.length === 0) {
    return <>{text}</>;
  }
  const hit = new Set(matches);
  const parts: { start: number; text: string; on: boolean }[] = [];
  for (let i = 0; i < text.length; i++) {
    const on = hit.has(i);
    const last = parts.at(-1);
    if (last && last.on === on) {
      last.text += text[i];
    } else {
      parts.push({ start: i, text: text[i] ?? "", on });
    }
  }
  return (
    <>
      {parts.map((p) =>
        p.on ? (
          <b
            className="font-semibold text-zinc-950 dark:text-white"
            key={p.start}
          >
            {p.text}
          </b>
        ) : (
          <span key={p.start}>{p.text}</span>
        )
      )}
    </>
  );
}

function Kbd({ children }: { children: ReactNode }) {
  return (
    <kbd className="inline-flex h-5 min-w-5 items-center justify-center rounded border border-zinc-200 bg-zinc-50 px-1 font-sans text-[11px] text-zinc-500 dark:border-zinc-800 dark:bg-zinc-900 dark:text-zinc-400">
      {children}
    </kbd>
  );
}

function RowEnd({
  item,
  status,
}: {
  item: CommandItem;
  status: "pending" | "done" | undefined;
}) {
  if (status === "pending") {
    return (
      <LoaderCircle
        aria-hidden="true"
        className="size-4 animate-spin text-zinc-500 dark:text-zinc-400"
      />
    );
  }
  if (status === "done") {
    return (
      <Check
        aria-hidden="true"
        className="size-4 text-zinc-900 dark:text-zinc-100"
      />
    );
  }
  if (item.children) {
    return <ChevronRight aria-hidden="true" className="size-4 text-zinc-400" />;
  }
  if (item.href) {
    return <ArrowUpRight aria-hidden="true" className="size-4 text-zinc-400" />;
  }
  if (item.shortcut) {
    return (
      <span aria-hidden="true" className="flex gap-0.5">
        {item.shortcut.map((key) => (
          <Kbd key={key}>{key}</Kbd>
        ))}
      </span>
    );
  }
  return null;
}

function isPaletteCombo(e: globalThis.KeyboardEvent) {
  return (
    (e.metaKey || e.ctrlKey) &&
    !e.altKey &&
    !e.shiftKey &&
    e.key.toLowerCase() === "k"
  );
}

/** Focus sits in an open modal dialog that does not hold the palette. */
function inOtherModal(focused: Element | null, root: HTMLElement) {
  const modal = focused?.closest('[aria-modal="true"]');
  return Boolean(modal && !modal.contains(root));
}

function useIsMac() {
  const [mac, setMac] = useState(true);
  useEffect(() => {
    setMac(APPLE_PLATFORM.test(navigator.userAgent));
  }, []);
  return mac;
}

/* ---------------------------------------------------------------- palette */

function ActionSearchBar({
  items = sampleItems,
  defaultRecent = ["copy-link", "theme-dark"],
  onSelect,
  onOpenChange,
  defaultOpen = false,
  shortcut = false,
  label = "Search commands",
  placeholder = "Search or jump to…",
  className,
}: ActionSearchBarProps) {
  const uid = useId();
  const inputId = `${uid}-input`;
  const listboxId = `${uid}-listbox`;
  const optionId = (index: number) => `${uid}-option-${index}`;

  const reduce = useReducedMotion();
  const isMac = useIsMac();

  const [open, setOpen] = useState(defaultOpen);
  const [query, setQuery] = useState("");
  const [stack, setStack] = useState<CommandItem[]>([]);
  const [activeIndex, setActiveIndex] = useState(0);
  const [running, setRunning] = useState<{
    key: string;
    phase: "pending" | "done";
  } | null>(null);
  const [recentIds, setRecentIds] = useState(defaultRecent);
  const [announcement, setAnnouncement] = useState("");

  const rootRef = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLInputElement>(null);
  const panelRef = useRef<HTMLDivElement>(null);
  const bodyRef = useRef<HTMLDivElement>(null);
  const contentRef = useRef<HTMLDivElement>(null);
  const listRef = useRef<HTMLDivElement>(null);
  const onScreenRef = useRef(true);
  const hoverRef = useRef(false);
  const fadeNextOpen = useRef(false);
  const slideNext = useRef<0 | 1 | -1>(0);
  const springUntil = useRef(0);
  const returnFocus = useRef<HTMLElement | null>(null);
  const holdTimer = useRef<number | undefined>(undefined);
  const runToken = useRef(0);

  const page = stack.at(-1);
  const recent = useMemo(
    () =>
      recentIds
        .map((id) => findEntry(items, id))
        .filter((e): e is Entry => e !== undefined && !e.item.children)
        .slice(0, RECENT_LIMIT),
    [recentIds, items]
  );
  const sections = useMemo(
    () => buildSections(page, items, query, recent),
    [page, items, query, recent]
  );
  const rows = useMemo(() => sections.flatMap((s) => s.rows), [sections]);
  const highlighted = Math.min(activeIndex, rows.length - 1);
  const activeRow = open ? rows[highlighted] : undefined;

  /* -- open / close -- */

  const setOpenState = useCallback(
    (next: boolean) => {
      setOpen(next);
      onOpenChange?.(next);
    },
    [onOpenChange]
  );

  const openPalette = useCallback(
    (source: InputSource) => {
      if (open) {
        return;
      }
      fadeNextOpen.current = source === "pointer";
      setActiveIndex(0);
      setOpenState(true);
    },
    [open, setOpenState]
  );

  const closePalette = useCallback(
    (restoreFocus: boolean) => {
      window.clearTimeout(holdTimer.current);
      runToken.current += 1;
      setRunning(null);
      setOpenState(false);
      setQuery("");
      setStack([]);
      setActiveIndex(0);
      const target = returnFocus.current;
      returnFocus.current = null;
      if (restoreFocus && target?.isConnected) {
        target.focus();
      }
    },
    [setOpenState]
  );

  useEffect(() => () => window.clearTimeout(holdTimer.current), []);

  /* -- ⌘K, only while the palette is on screen -- */

  useEffect(() => {
    const root = rootRef.current;
    if (!root) {
      return;
    }
    const io = new IntersectionObserver(([entry]) => {
      onScreenRef.current = entry?.isIntersecting ?? true;
    });
    io.observe(root);
    return () => io.disconnect();
  }, []);

  const hotkeyState = useRef({ open, openPalette, closePalette });
  useEffect(() => {
    hotkeyState.current = { open, openPalette, closePalette };
  });

  useEffect(() => {
    const onKey = (e: globalThis.KeyboardEvent) => {
      const root = rootRef.current;
      if (
        !(isPaletteCombo(e) && root && onScreenRef.current) ||
        e.defaultPrevented
      ) {
        return;
      }
      const focused = document.activeElement;
      const focusedInside = focused instanceof Node && root.contains(focused);
      if (!(shortcut || focusedInside || hoverRef.current)) {
        return;
      }
      if (inOtherModal(focused, root)) {
        return;
      }
      e.preventDefault();
      e.stopPropagation();
      const state = hotkeyState.current;
      if (state.open) {
        state.closePalette(true);
        return;
      }
      if (focused instanceof HTMLElement && !focusedInside) {
        returnFocus.current = focused;
      }
      inputRef.current?.focus();
      inputRef.current?.select();
      state.openPalette("keyboard");
    };
    // Capture, so the host page's ⌘K does not also fire when this one takes it.
    window.addEventListener("keydown", onKey, true);
    return () => window.removeEventListener("keydown", onKey, true);
  }, [shortcut]);

  /* -- motion: fade on pointer open; slide + spring on pointer page change -- */

  useLayoutEffect(() => {
    const panel = panelRef.current;
    if (!(open && panel && fadeNextOpen.current)) {
      return;
    }
    fadeNextOpen.current = false;
    panel.animate([{ opacity: 0 }, { opacity: 1 }], {
      duration: 120,
      easing: EASE_OUT,
    });
  }, [open]);

  useLayoutEffect(() => {
    const body = bodyRef.current;
    const content = contentRef.current;
    if (!(open && body && content)) {
      return;
    }
    let controls: ReturnType<typeof animate> | undefined;
    const fitHeight = () => {
      const h = `${content.offsetHeight}px`;
      controls?.stop();
      if (!reduce && performance.now() < springUntil.current) {
        controls = animate(
          body,
          { height: h },
          { type: "spring", bounce: 0, duration: 0.32 }
        );
      } else {
        body.style.height = h;
      }
    };
    fitHeight();
    const ro = new ResizeObserver(fitHeight);
    ro.observe(content);
    return () => {
      ro.disconnect();
      controls?.stop();
    };
  }, [open, reduce]);

  // biome-ignore lint/correctness/useExhaustiveDependencies: runs when the page changes
  useLayoutEffect(() => {
    const list = listRef.current;
    const dir = slideNext.current;
    slideNext.current = 0;
    if (!list || dir === 0) {
      return;
    }
    list.animate(
      [
        {
          transform: reduce ? "none" : `translateX(${dir * 14}px)`,
          opacity: 0,
        },
        { transform: "none", opacity: 1 },
      ],
      { duration: 200, easing: EASE_OUT }
    );
  }, [stack.length]);

  // Keep the highlighted row inside the list's scroll box (never the page).
  // biome-ignore lint/correctness/useExhaustiveDependencies: optionId is derived from uid
  useLayoutEffect(() => {
    const list = listRef.current;
    const row = document.getElementById(optionId(highlighted));
    if (!(open && list && row)) {
      return;
    }
    const top = row.offsetTop;
    const bottom = top + row.offsetHeight;
    if (top < list.scrollTop + 6) {
      list.scrollTop = top - 30;
    } else if (bottom > list.scrollTop + list.clientHeight - 6) {
      list.scrollTop = bottom - list.clientHeight + 6;
    }
  }, [open, highlighted, sections]);

  /* -- pages -- */

  const pushPage = (item: CommandItem, source: InputSource) => {
    if (source === "pointer") {
      slideNext.current = 1;
      springUntil.current = performance.now() + 150;
    }
    setStack((s) => [...s, item]);
    setQuery("");
    setActiveIndex(0);
    setAnnouncement(`${item.label}, ${item.children?.length ?? 0} options`);
  };

  const popPage = (source: InputSource) => {
    const left = stack.at(-1);
    if (!left) {
      return;
    }
    if (source === "pointer") {
      slideNext.current = -1;
      springUntil.current = performance.now() + 150;
    }
    const nextStack = stack.slice(0, -1);
    setStack(nextStack);
    setQuery("");
    // Land back on the row that opened the page.
    const back = buildSections(nextStack.at(-1), items, "", recent)
      .flatMap((s) => s.rows)
      .findIndex((r) => r.key === left.id);
    setActiveIndex(Math.max(0, back));
    setAnnouncement(nextStack.at(-1)?.label ?? "All commands");
    inputRef.current?.focus();
  };

  /* -- running -- */

  const finishRun = (row: Row, token: number) => {
    if (token !== runToken.current) {
      return;
    }
    setRunning({ key: row.key, phase: "done" });
    setAnnouncement(`${row.item.label}, done`);
    holdTimer.current = window.setTimeout(() => {
      if (token !== runToken.current) {
        return;
      }
      setRecentIds((ids) =>
        [row.item.id, ...ids.filter((id) => id !== row.item.id)].slice(
          0,
          RECENT_LIMIT
        )
      );
      closePalette(returnFocus.current !== null);
    }, HOLD_MS);
  };

  const runRow = (row: Row) => {
    runToken.current += 1;
    const token = runToken.current;
    const result = onSelect?.(row.item, [...stack, ...row.path]);
    if (!(result instanceof Promise)) {
      finishRun(row, token);
      return;
    }
    setRunning({ key: row.key, phase: "pending" });
    setAnnouncement(`Running ${row.item.label}`);
    result.then(
      () => finishRun(row, token),
      () => {
        if (token === runToken.current) {
          setRunning(null);
          setAnnouncement(`${row.item.label} failed`);
        }
      }
    );
  };

  const choose = (row: Row, source: InputSource) => {
    if (running) {
      return;
    }
    if (row.item.children) {
      pushPage(row.item, source);
    } else {
      runRow(row);
    }
  };

  /* -- input -- */

  const moveHighlight = (step: number) => {
    const count = rows.length;
    if (count > 0) {
      setActiveIndex((Math.max(highlighted, 0) + step + count) % count);
    }
  };

  const handleNavKey = (e: KeyboardEvent<HTMLInputElement>) => {
    if (!open) {
      e.preventDefault();
      openPalette("keyboard");
      return;
    }
    if (rows.length === 0) {
      return;
    }
    e.preventDefault();
    if (e.key === "Home" || e.key === "End") {
      setActiveIndex(e.key === "Home" ? 0 : rows.length - 1);
    } else {
      moveHighlight(e.key === "ArrowDown" ? 1 : -1);
    }
  };

  const handleEnter = (e: KeyboardEvent<HTMLInputElement>) => {
    e.preventDefault();
    if (!open) {
      openPalette("keyboard");
    } else if (activeRow) {
      choose(activeRow, "keyboard");
    }
  };

  const handleEscape = (e: KeyboardEvent<HTMLInputElement>) => {
    if (open) {
      e.preventDefault();
      closePalette(true);
    } else if (query) {
      setQuery("");
    }
  };

  const handleKeyDown = (e: KeyboardEvent<HTMLInputElement>) => {
    if (running && e.key !== "Tab") {
      e.preventDefault();
      return;
    }
    switch (e.key) {
      case "ArrowDown":
      case "ArrowUp":
      case "Home":
      case "End":
        handleNavKey(e);
        break;
      case "Enter":
        handleEnter(e);
        break;
      case "Backspace":
        if (open && query === "" && stack.length > 0) {
          e.preventDefault();
          popPage("keyboard");
        }
        break;
      case "Escape":
        handleEscape(e);
        break;
      default:
        break;
    }
  };

  const handleChange = (e: ChangeEvent<HTMLInputElement>) => {
    setQuery(e.target.value);
    setActiveIndex(0);
    openPalette("keyboard");
  };

  const handleInputPointerDown = (e: PointerEvent<HTMLInputElement>) => {
    if (e.button === 0) {
      openPalette("pointer");
    }
  };

  // Close when focus leaves the whole palette (Tab away, click outside).
  const handleBlur = (e: FocusEvent<HTMLDivElement>) => {
    const next = e.relatedTarget;
    if (open && !(next instanceof Node && e.currentTarget.contains(next))) {
      returnFocus.current = null;
      closePalette(false);
    }
  };

  const pagePlaceholder = page
    ? (page.placeholder ?? `Search ${page.label.toLowerCase()}…`)
    : placeholder;

  let rowIndex = -1;

  return (
    // biome-ignore lint/a11y/noStaticElementInteractions: focusout from the whole palette closes it
    // biome-ignore lint/a11y/noNoninteractiveElementInteractions: same focusout handler
    <div
      className={cn("relative h-[46px] w-full max-w-md", className)}
      onBlur={handleBlur}
      onPointerEnter={(e) => {
        hoverRef.current = e.pointerType === "mouse";
      }}
      onPointerLeave={() => {
        hoverRef.current = false;
      }}
      ref={rootRef}
    >
      <div
        className={cn(
          "@container/palette absolute inset-x-0 top-0 z-30 overflow-hidden rounded-xl border border-zinc-200 bg-white dark:border-zinc-800 dark:bg-zinc-950",
          open
            ? "shadow-[0_16px_40px_-16px_rgb(0_0_0/0.2)] dark:shadow-[0_16px_40px_-16px_rgb(0_0_0/0.7)]"
            : "shadow-xs"
        )}
      >
        <div className="flex h-11 items-center gap-2 px-3">
          <Search
            aria-hidden="true"
            className="size-4 shrink-0 text-zinc-400 dark:text-zinc-500"
          />
          {stack.map((p, i) => (
            <button
              aria-label={`Back from ${p.label}`}
              className="inline-flex h-6 shrink-0 items-center rounded-md bg-zinc-100 px-2 font-medium text-xs text-zinc-700 hover:bg-zinc-200 dark:bg-zinc-800 dark:text-zinc-200 dark:hover:bg-zinc-700"
              key={p.id}
              onClick={() => {
                if (i === stack.length - 1 && !running) {
                  popPage("pointer");
                }
              }}
              // Keep focus in the input; Backspace is the keyboard path.
              onPointerDown={(e) => e.preventDefault()}
              tabIndex={-1}
              type="button"
            >
              {p.label}
            </button>
          ))}
          <label className="sr-only" htmlFor={inputId}>
            {label}
          </label>
          <input
            aria-activedescendant={
              activeRow ? optionId(highlighted) : undefined
            }
            aria-autocomplete="list"
            aria-controls={open ? listboxId : undefined}
            aria-expanded={open}
            autoComplete="off"
            className="h-full min-w-0 flex-1 bg-transparent text-sm text-zinc-900 outline-none placeholder:text-zinc-400 dark:text-zinc-100 dark:placeholder:text-zinc-500"
            id={inputId}
            onChange={handleChange}
            onKeyDown={handleKeyDown}
            onPointerDown={handleInputPointerDown}
            placeholder={pagePlaceholder}
            readOnly={running !== null}
            ref={inputRef}
            role="combobox"
            spellCheck={false}
            type="text"
            value={query}
          />
          {!open && (
            <span aria-hidden="true" className="flex shrink-0 gap-0.5">
              <Kbd>{isMac ? "⌘" : "Ctrl"}</Kbd>
              <Kbd>K</Kbd>
            </span>
          )}
        </div>

        {open && (
          <div
            // Keep focus in the input while pressing inside the list, so its
            // blur never closes the palette before the click lands.
            onPointerDown={(e) => e.preventDefault()}
            ref={panelRef}
          >
            <div className="border-zinc-100 border-t dark:border-zinc-800/80" />
            <div className="overflow-hidden" ref={bodyRef}>
              <div ref={contentRef}>
                <div
                  aria-busy={running?.phase === "pending"}
                  aria-label={page ? page.label : "Commands"}
                  className="relative max-h-72 overflow-y-auto overscroll-contain p-1.5"
                  id={listboxId}
                  ref={listRef}
                  role="listbox"
                >
                  {sections.map((section) => (
                    // biome-ignore lint/a11y/useSemanticElements: ARIA listbox groups, not a form fieldset
                    <div
                      aria-labelledby={
                        section.label ? `${uid}-${section.key}` : undefined
                      }
                      key={section.key}
                      role="group"
                    >
                      {section.label && (
                        <div
                          className="px-2 pt-2 pb-1 font-medium text-[11px] text-zinc-500 dark:text-zinc-400"
                          id={`${uid}-${section.key}`}
                          role="presentation"
                        >
                          {section.label}
                        </div>
                      )}
                      {section.rows.map((row) => {
                        rowIndex += 1;
                        const index = rowIndex;
                        const status =
                          running?.key === row.key ? running.phase : undefined;
                        return (
                          // biome-ignore lint/a11y/useFocusableInteractive: combobox pattern, focus stays in the input (aria-activedescendant)
                          // biome-ignore lint/a11y/useKeyWithClickEvents: keys are handled by the input
                          <div
                            aria-disabled={running !== null && !status}
                            aria-selected={index === highlighted}
                            className="group/row flex h-9 cursor-default items-center gap-2.5 rounded-md px-2 text-sm text-zinc-700 aria-disabled:opacity-50 aria-selected:bg-zinc-100 dark:text-zinc-300 dark:aria-selected:bg-zinc-800/70"
                            id={optionId(index)}
                            key={row.key}
                            onClick={() => choose(row, "pointer")}
                            onPointerMove={(e) => {
                              if (
                                e.pointerType === "mouse" &&
                                !running &&
                                index !== highlighted
                              ) {
                                setActiveIndex(index);
                              }
                            }}
                            role="option"
                          >
                            <span
                              aria-hidden="true"
                              className="flex size-4 shrink-0 items-center justify-center text-zinc-400 group-aria-selected/row:text-zinc-700 dark:text-zinc-500 dark:group-aria-selected/row:text-zinc-200"
                            >
                              {row.item.icon}
                            </span>
                            <span className="min-w-0 flex-1 truncate">
                              {row.path.map((p) => (
                                <span
                                  className="text-zinc-400 dark:text-zinc-500"
                                  key={p.id}
                                >
                                  {p.label}
                                  <span aria-hidden="true"> › </span>
                                </span>
                              ))}
                              <Highlighted
                                matches={row.matches}
                                text={row.item.label}
                              />
                              {row.item.children && (
                                <span className="sr-only">, opens a page</span>
                              )}
                            </span>
                            <span className="flex shrink-0 items-center">
                              <RowEnd item={row.item} status={status} />
                            </span>
                          </div>
                        );
                      })}
                    </div>
                  ))}
                </div>
                {rows.length === 0 && (
                  <p className="px-3 pt-1 pb-6 text-center text-sm text-zinc-500 dark:text-zinc-400">
                    No results for “{query.trim()}”
                  </p>
                )}
              </div>
            </div>
            <div className="flex items-center justify-between gap-3 border-zinc-100 border-t px-3 py-2 text-[11px] text-zinc-500 dark:border-zinc-800/80 dark:text-zinc-400">
              <span className="flex items-center gap-1.5">
                <span className="@xs/palette:flex hidden items-center gap-1.5">
                  <Kbd>↑</Kbd>
                  <Kbd>↓</Kbd>
                  <span className="mr-1.5">Navigate</span>
                </span>
                <Kbd>↵</Kbd>
                <span>{activeRow?.item.children ? "Open" : "Run"}</span>
              </span>
              <span className="flex items-center gap-1.5">
                {stack.length > 0 && (
                  <>
                    <Kbd>⌫</Kbd>
                    <span className="mr-1.5">Back</span>
                  </>
                )}
                <Kbd>esc</Kbd>
                <span>Close</span>
              </span>
            </div>
          </div>
        )}
      </div>
      <span aria-live="polite" className="sr-only">
        {announcement}
      </span>
    </div>
  );
}

export default ActionSearchBar;
```


---

# Marking Menu
> A radial menu you hold to open or flick to pick blind, built with React and Motion.

Source: https://kokonutui.com/docs/navigation/marking-menu

## Installation

```bash
npx shadcn@latest add @kokonutui/marking-menu
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Marking Menu
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  CalendarDays,
  Folder,
  House,
  Inbox,
  type LucideIcon,
  PenLine,
  Search,
  Settings,
  User,
} from "lucide-react";
import { AnimatePresence, animate, motion, useMotionValue } from "motion/react";
import {
  type KeyboardEvent as ReactKeyboardEvent,
  type MouseEvent as ReactMouseEvent,
  type ReactNode,
  type PointerEvent as ReactPointerEvent,
  useCallback,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface MarkingMenuItem {
  id: string;
  label: string;
  icon: LucideIcon;
}

export interface MarkingMenuProps {
  /** Up to eight destinations, laid out clockwise from the top. */
  items?: MarkingMenuItem[];
  /** Called with the item picked, by menu, flick or keyboard. */
  onSelect?: (item: MarkingMenuItem) => void;
  /** The surface the menu opens over. Defaults to a small demo page. */
  children?: ReactNode;
  className?: string;
}

const DEFAULT_ITEMS: MarkingMenuItem[] = [
  { id: "home", label: "Home", icon: House },
  { id: "inbox", label: "Inbox", icon: Inbox },
  { id: "calendar", label: "Calendar", icon: CalendarDays },
  { id: "files", label: "Files", icon: Folder },
  { id: "search", label: "Search", icon: Search },
  { id: "compose", label: "Compose", icon: PenLine },
  { id: "profile", label: "Profile", icon: User },
  { id: "settings", label: "Settings", icon: Settings },
];

// Hold this long without moving and the menu appears under the finger.
// Move further than FLICK first and it never does: the stroke alone picks.
const HOLD_MS = 180;
const FLICK = 36;
// Inside this radius nothing is picked; letting go there cancels.
const DEAD_ZONE = 24;
// Geometry of the disc, in px.
const DISC = 112;
const RING = 78;
const HUB = 30;
// Selected items lean towards the pointer by this much.
const LEAN = 7;
// How long the stroke's tail stays on screen.
const TRAIL_MS = 260;
const EASE_OUT = [0.23, 1, 0.32, 1] as const;

// Arrow keys walk round the ring: right and down go clockwise.
const MOVE_KEYS: Record<string, number> = {
  ArrowRight: 1,
  ArrowDown: 1,
  ArrowLeft: -1,
  ArrowUp: -1,
};

type Mode = "press" | "sticky";

interface OpenMenu {
  // Where the disc is drawn: the press point, nudged inside the surface.
  x: number;
  y: number;
  mode: Mode;
  fromKeyboard: boolean;
}

interface Gesture {
  id: number;
  x: number;
  y: number;
  stage: "pending" | "menu" | "flick";
  timer: number;
}

const round = (n: number) => Math.round(n * 100) / 100;

/** Item index for a direction, clockwise from the top, or -1 if too short. */
function pick(dx: number, dy: number, count: number) {
  if (Math.hypot(dx, dy) < DEAD_ZONE) {
    return -1;
  }
  const angle = (Math.atan2(dy, dx) * 180) / Math.PI + 90;
  const step = 360 / count;
  return Math.round((((angle % 360) + 360) % 360) / step) % count;
}

/** A ring sector pointing up, spanning `span` degrees. */
function sectorPath(span: number) {
  const half = ((span / 2 - 1.5) * Math.PI) / 180;
  const inner = HUB + 5;
  const outer = DISC - 5;
  const point = (r: number, a: number) =>
    `${round(r * Math.sin(a))} ${round(-r * Math.cos(a))}`;
  return [
    `M${point(inner, -half)}`,
    `L${point(outer, -half)}`,
    `A${outer} ${outer} 0 0 1 ${point(outer, half)}`,
    `L${point(inner, half)}`,
    `A${inner} ${inner} 0 0 0 ${point(inner, -half)}`,
    "Z",
  ].join(" ");
}

function haptic() {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(4);
  }
}

export default function MarkingMenu({
  items = DEFAULT_ITEMS,
  onSelect,
  children,
  className,
}: MarkingMenuProps) {
  const list = items.slice(0, 8);
  const count = list.length;
  const step = 360 / count;
  const menuId = useId();

  const surfaceRef = useRef<HTMLDivElement>(null);
  const triggerRef = useRef<HTMLButtonElement>(null);
  const menuRef = useRef<HTMLDivElement>(null);
  const aimRef = useRef<HTMLDivElement>(null);
  const trailRef = useRef<SVGPathElement>(null);
  const gestureRef = useRef<Gesture | null>(null);
  const trailPoints = useRef<{ x: number; y: number; t: number }[]>([]);
  const trailFrame = useRef(0);

  const [open, setOpen] = useState<OpenMenu | null>(null);
  const [selected, setSelected] = useState(-1);
  const [current, setCurrent] = useState(list[0]);
  const [flash, setFlash] = useState<{
    item: MarkingMenuItem;
    x: number;
    y: number;
    key: number;
  } | null>(null);

  // Live mirrors for pointer handlers, which must not wait for a render.
  const openRef = useRef(open);
  openRef.current = open;
  const selectedRef = useRef(selected);
  selectedRef.current = selected;

  // The highlight swings round to the picked slice on a spring, always the
  // short way.
  const wedge = useMotionValue(0);

  useEffect(() => {
    if (selected < 0) {
      return;
    }
    const from = wedge.get();
    const to = selected * step;
    const delta = ((((to - from) % 360) + 540) % 360) - 180;
    const controls = animate(wedge, from + delta, {
      type: "spring",
      stiffness: 520,
      damping: 36,
    });
    return () => controls.stop();
  }, [selected, step, wedge]);

  const local = useCallback((event: { clientX: number; clientY: number }) => {
    const rect = surfaceRef.current?.getBoundingClientRect();
    return {
      x: event.clientX - (rect?.left ?? 0),
      y: event.clientY - (rect?.top ?? 0),
    };
  }, []);

  /** Where to draw the disc so it stays inside the surface. */
  const place = useCallback((x: number, y: number) => {
    const rect = surfaceRef.current?.getBoundingClientRect();
    const w = rect?.width ?? 0;
    const h = rect?.height ?? 0;
    const pad = DISC + 8;
    return {
      x: w > pad * 2 ? Math.min(Math.max(x, pad), w - pad) : w / 2,
      y: h > pad * 2 ? Math.min(Math.max(y, pad), h - pad) : h / 2,
    };
  }, []);

  const select = useCallback((index: number) => {
    if (index !== selectedRef.current) {
      selectedRef.current = index;
      setSelected(index);
      if (index >= 0) {
        haptic();
      }
    }
  }, []);

  /** Point the aim tick at the pointer and pick the slice it is in. */
  const aim = useCallback(
    (x: number, y: number) => {
      const menu = openRef.current;
      if (!menu) {
        return;
      }
      const dx = x - menu.x;
      const dy = y - menu.y;
      const tick = aimRef.current;
      if (tick) {
        const away = Math.hypot(dx, dy) >= DEAD_ZONE;
        tick.style.opacity = away ? "1" : "0";
        tick.style.transform = `rotate(${Math.atan2(dy, dx) + Math.PI / 2}rad)`;
      }
      select(pick(dx, dy, count));
    },
    [count, select]
  );

  const close = useCallback(() => {
    const menu = openRef.current;
    openRef.current = null;
    setOpen(null);
    select(-1);
    if (menu?.fromKeyboard) {
      triggerRef.current?.focus();
    }
  }, [select]);

  const commit = useCallback(
    (index: number, at?: { x: number; y: number }) => {
      const item = list[index];
      if (item) {
        setCurrent(item);
        onSelect?.(item);
        if (at) {
          setFlash({ item, ...at, key: performance.now() });
        }
      }
      close();
    },
    [list, onSelect, close]
  );

  const show = useCallback(
    (x: number, y: number, mode: Mode, fromKeyboard = false) => {
      const at = place(x, y);
      const menu = { ...at, mode, fromKeyboard };
      openRef.current = menu;
      setOpen(menu);
      select(fromKeyboard ? 0 : -1);
    },
    [place, select]
  );

  // The stroke the pointer leaves while pressed, eaten from its tail.
  const drawTrail = useCallback(() => {
    trailFrame.current = 0;
    const now = performance.now();
    const points = trailPoints.current;
    while (points.length > 0 && now - points[0].t > TRAIL_MS) {
      points.shift();
    }
    const path = trailRef.current;
    if (path) {
      path.setAttribute(
        "d",
        points
          .map((p, i) => `${i === 0 ? "M" : "L"}${round(p.x)} ${round(p.y)}`)
          .join("")
      );
    }
    if (points.length > 0) {
      trailFrame.current = requestAnimationFrame(drawTrail);
    }
  }, []);

  const addTrail = useCallback(
    (x: number, y: number) => {
      trailPoints.current.push({ x, y, t: performance.now() });
      if (!trailFrame.current) {
        trailFrame.current = requestAnimationFrame(drawTrail);
      }
    },
    [drawTrail]
  );

  useEffect(
    () => () => {
      cancelAnimationFrame(trailFrame.current);
      window.clearTimeout(gestureRef.current?.timer);
    },
    []
  );

  const onPointerDown = (event: ReactPointerEvent<HTMLDivElement>) => {
    if (event.button !== 0 || gestureRef.current) {
      return;
    }
    if ((event.target as HTMLElement).closest("[data-marking-trigger]")) {
      return;
    }
    const p = local(event);
    const menu = openRef.current;
    if (menu?.mode === "sticky") {
      // A sticky menu (right click, keyboard) is picked with a click.
      aim(p.x, p.y);
      commit(selectedRef.current);
      return;
    }
    event.preventDefault();
    event.currentTarget.setPointerCapture(event.pointerId);
    const gesture: Gesture = {
      id: event.pointerId,
      x: p.x,
      y: p.y,
      stage: "pending",
      timer: window.setTimeout(() => {
        if (gestureRef.current === gesture && gesture.stage === "pending") {
          gesture.stage = "menu";
          show(gesture.x, gesture.y, "press");
        }
      }, HOLD_MS),
    };
    gestureRef.current = gesture;
    addTrail(p.x, p.y);
  };

  const onPointerMove = (event: ReactPointerEvent<HTMLDivElement>) => {
    const p = local(event);
    const gesture = gestureRef.current;
    if (!gesture) {
      if (openRef.current?.mode === "sticky") {
        aim(p.x, p.y);
      }
      return;
    }
    if (event.pointerId !== gesture.id) {
      return;
    }
    addTrail(p.x, p.y);
    if (
      gesture.stage === "pending" &&
      Math.hypot(p.x - gesture.x, p.y - gesture.y) > FLICK
    ) {
      // Moving off before the menu shows: an expert stroke. No menu, the
      // direction alone decides.
      window.clearTimeout(gesture.timer);
      gesture.stage = "flick";
    }
    if (gesture.stage === "menu") {
      aim(p.x, p.y);
    }
  };

  const onPointerUp = (event: ReactPointerEvent<HTMLDivElement>) => {
    const gesture = gestureRef.current;
    if (!gesture || event.pointerId !== gesture.id) {
      return;
    }
    gestureRef.current = null;
    window.clearTimeout(gesture.timer);
    const p = local(event);
    if (gesture.stage === "menu") {
      aim(p.x, p.y);
      commit(selectedRef.current);
    } else if (gesture.stage === "flick") {
      commit(pick(p.x - gesture.x, p.y - gesture.y, count), p);
    }
  };

  const onPointerCancel = (event: ReactPointerEvent<HTMLDivElement>) => {
    const gesture = gestureRef.current;
    if (gesture && event.pointerId === gesture.id) {
      window.clearTimeout(gesture.timer);
      gestureRef.current = null;
      close();
    }
  };

  const onContextMenu = (event: ReactMouseEvent<HTMLDivElement>) => {
    event.preventDefault();
    const gesture = gestureRef.current;
    if (gesture) {
      window.clearTimeout(gesture.timer);
      gestureRef.current = null;
    }
    const p = local(event);
    show(p.x, p.y, "sticky");
  };

  const openFromKeyboard = () => {
    const rect = surfaceRef.current?.getBoundingClientRect();
    show((rect?.width ?? 0) / 2, (rect?.height ?? 0) / 2, "sticky", true);
  };

  useEffect(() => {
    if (open?.fromKeyboard) {
      menuRef.current?.focus();
    }
  }, [open]);

  const onMenuKeyDown = (event: ReactKeyboardEvent<HTMLDivElement>) => {
    const index = selectedRef.current;
    const move = MOVE_KEYS[event.key];
    const digit = Number.parseInt(event.key, 10);
    if (move) {
      event.preventDefault();
      // From nothing picked, the first step lands on the top item.
      let from = index;
      if (index < 0) {
        from = move > 0 ? -1 : 1;
      }
      select((from + move + count) % count);
    } else if (event.key === "Enter" || event.key === " ") {
      event.preventDefault();
      commit(index);
    } else if (event.key === "Escape" || event.key === "Tab") {
      close();
    } else if (digit >= 1 && digit <= count) {
      event.preventDefault();
      commit(digit - 1);
    }
  };

  const Current = current?.icon ?? House;
  const active = selected >= 0 ? list[selected] : undefined;

  return (
    // biome-ignore lint/a11y/noStaticElementInteractions: a gesture surface; the Menu button is its keyboard path.
    // biome-ignore lint/a11y/noNoninteractiveElementInteractions: same as above.
    <div
      className={cn(
        "relative h-[440px] w-full touch-none select-none overflow-hidden rounded-2xl border border-zinc-200 bg-zinc-50 text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        open ? "cursor-default" : "cursor-crosshair",
        className
      )}
      onContextMenu={onContextMenu}
      onPointerCancel={onPointerCancel}
      onPointerDown={onPointerDown}
      onPointerMove={onPointerMove}
      onPointerUp={onPointerUp}
      ref={surfaceRef}
    >
      {children ?? (
        <div className="pointer-events-none absolute inset-0 flex flex-col p-5">
          <div className="flex items-center gap-2.5">
            <span className="flex size-8 items-center justify-center rounded-lg border border-zinc-200 bg-white dark:border-zinc-800 dark:bg-zinc-900">
              <Current className="size-4" strokeWidth={1.75} />
            </span>
            <AnimatePresence initial={false} mode="popLayout">
              <motion.span
                animate={{ opacity: 1, filter: "blur(0px)" }}
                className="font-medium text-sm"
                exit={{ opacity: 0, filter: "blur(2px)" }}
                initial={{ opacity: 0, filter: "blur(2px)" }}
                key={current?.id}
                transition={{ duration: 0.18, ease: EASE_OUT }}
              >
                {current?.label}
              </motion.span>
            </AnimatePresence>
          </div>
          <div className="flex flex-1 flex-col items-center justify-center gap-1.5 text-center">
            <p className="text-sm text-zinc-500 dark:text-zinc-400">
              Press and hold anywhere, or flick
            </p>
            <p className="text-xs text-zinc-400 dark:text-zinc-500">
              Right click opens it too
            </p>
          </div>
        </div>
      )}

      <svg
        aria-hidden="true"
        className="pointer-events-none absolute inset-0 h-full w-full text-zinc-400 dark:text-zinc-600"
      >
        <path
          fill="none"
          ref={trailRef}
          stroke="currentColor"
          strokeLinecap="round"
          strokeLinejoin="round"
          strokeWidth={2}
        />
      </svg>

      <button
        aria-controls={open ? menuId : undefined}
        aria-expanded={Boolean(open)}
        aria-haspopup="menu"
        className="absolute top-4 right-4 rounded-lg border border-zinc-200 bg-white px-2.5 py-1.5 font-medium text-xs text-zinc-600 transition-colors duration-150 ease-out hover:text-zinc-900 focus-visible:outline-2 focus-visible:outline-zinc-400 focus-visible:outline-offset-2 dark:border-zinc-800 dark:bg-zinc-900 dark:text-zinc-400 dark:hover:text-zinc-100"
        data-marking-trigger=""
        onClick={openFromKeyboard}
        ref={triggerRef}
        type="button"
      >
        Menu
      </button>

      <AnimatePresence>
        {open ? (
          <motion.div
            animate={{ opacity: 1, scale: 1 }}
            aria-activedescendant={
              active ? `${menuId}-${active.id}` : undefined
            }
            aria-label="Go to"
            className="absolute outline-none"
            exit={{ opacity: 0, scale: 0.97, transition: { duration: 0.12 } }}
            id={menuId}
            initial={{ opacity: 0, scale: 0.94 }}
            key="menu"
            onKeyDown={onMenuKeyDown}
            ref={menuRef}
            role="menu"
            style={{
              left: open.x - DISC,
              top: open.y - DISC,
              width: DISC * 2,
              height: DISC * 2,
            }}
            tabIndex={-1}
            transition={{ duration: 0.16, ease: EASE_OUT }}
          >
            <div className="absolute inset-0 rounded-full border border-zinc-200 bg-white shadow-[0_8px_30px_rgb(0_0_0/0.08)] dark:border-zinc-800 dark:bg-zinc-900 dark:shadow-[0_8px_30px_rgb(0_0_0/0.5)]" />
            <motion.div
              animate={{ opacity: selected >= 0 ? 1 : 0 }}
              aria-hidden="true"
              className="absolute inset-0"
              initial={{ opacity: 0 }}
              style={{ rotate: wedge }}
              transition={{ duration: 0.12 }}
            >
              <svg
                aria-hidden="true"
                className="overflow-visible"
                height={DISC * 2}
                viewBox={`${-DISC} ${-DISC} ${DISC * 2} ${DISC * 2}`}
                width={DISC * 2}
              >
                <path
                  className="fill-zinc-100 dark:fill-zinc-800"
                  d={sectorPath(step)}
                />
              </svg>
            </motion.div>

            {list.map((item, index) => {
              const angle = ((index * step - 90) * Math.PI) / 180;
              const cos = Math.cos(angle);
              const sin = Math.sin(angle);
              const isSelected = index === selected;
              const Icon = item.icon;
              return (
                <motion.div
                  animate={{
                    opacity: 1,
                    x: round(cos * (RING + (isSelected ? LEAN : 0))),
                    y: round(sin * (RING + (isSelected ? LEAN : 0))),
                  }}
                  aria-label={item.label}
                  className={cn(
                    "absolute top-1/2 left-1/2 -mt-5 -ml-5 flex size-10 items-center justify-center rounded-full transition-colors duration-150 ease-out",
                    isSelected
                      ? "text-zinc-900 dark:text-white"
                      : "text-zinc-400 dark:text-zinc-500"
                  )}
                  id={`${menuId}-${item.id}`}
                  initial={{
                    opacity: 0,
                    x: round(cos * RING * 0.55),
                    y: round(sin * RING * 0.55),
                  }}
                  key={item.id}
                  role="menuitem"
                  transition={{
                    type: "spring",
                    stiffness: 600,
                    damping: 34,
                    delay: open.mode === "press" ? index * 0.015 : 0,
                  }}
                >
                  <Icon className="size-[18px]" strokeWidth={1.75} />
                </motion.div>
              );
            })}

            {/* The hub names the slice; the tick on its rim follows the
                pointer exactly, while the highlight springs after it. */}
            <div
              className="absolute top-1/2 left-1/2 flex items-center justify-center rounded-full border border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-950"
              style={{
                width: HUB * 2,
                height: HUB * 2,
                marginLeft: -HUB,
                marginTop: -HUB,
              }}
            >
              <div
                className="absolute inset-0 opacity-0 transition-opacity duration-100"
                ref={aimRef}
              >
                <span className="absolute top-[3px] left-1/2 size-1 -translate-x-1/2 rounded-full bg-zinc-900 dark:bg-zinc-100" />
              </div>
              <AnimatePresence initial={false} mode="popLayout">
                <motion.span
                  animate={{ opacity: 1, filter: "blur(0px)" }}
                  className="font-medium text-[11px] text-zinc-600 dark:text-zinc-300"
                  exit={{ opacity: 0, filter: "blur(2px)" }}
                  initial={{ opacity: 0, filter: "blur(2px)" }}
                  key={active?.id ?? "none"}
                  transition={{ duration: 0.12, ease: EASE_OUT }}
                >
                  {active?.label ?? ""}
                </motion.span>
              </AnimatePresence>
            </div>
          </motion.div>
        ) : null}
      </AnimatePresence>

      {/* After a flick, the pick shows briefly where the stroke ended, so
          the hand learns the direction without ever seeing the menu. */}
      <AnimatePresence>
        {flash ? (
          <motion.div
            animate={{ opacity: [0, 1, 1, 0], y: [4, 0, 0, -4] }}
            className="pointer-events-none absolute flex items-center gap-1.5 rounded-full border border-zinc-200 bg-white px-2.5 py-1 font-medium text-xs shadow-sm dark:border-zinc-800 dark:bg-zinc-900"
            key={flash.key}
            onAnimationComplete={() => setFlash(null)}
            style={{ left: flash.x + 12, top: flash.y - 32 }}
            transition={{ duration: 0.9, times: [0, 0.15, 0.7, 1] }}
          >
            <flash.item.icon className="size-3.5" strokeWidth={1.75} />
            {flash.item.label}
          </motion.div>
        ) : null}
      </AnimatePresence>
    </div>
  );
}
```


---

# Split Nav
> Navigation bar that splits around the active link, with drag-to-scrub, flick projection and an optional compact fold.

Source: https://kokonutui.com/docs/navigation/morphic-navbar

## Installation

```bash
npx shadcn@latest add @kokonutui/morphic-navbar
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Split Nav
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  animate,
  type MotionValue,
  motion,
  motionValue,
  useMotionValue,
  useReducedMotion,
  useTransform,
} from "motion/react";
import Link from "next/link";
import { usePathname } from "next/navigation";
import {
  type FocusEvent,
  type KeyboardEvent,
  type MouseEvent,
  type PointerEvent,
  type Ref,
  useEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface NavItem {
  name: string;
}

export interface MorphicNavbarProps {
  /** Links keyed by their href, in display order. */
  items?: Record<string, NavItem>;
  /**
   * Initially active path. Defaults to the first item's path. When an item's
   * path matches the current route, that item is active instead.
   */
  defaultPath?: string;
  /**
   * After 80px of page scroll, fold the bar down to the active link plus a
   * chevron that opens it again.
   */
  compact?: boolean;
  className?: string;
}

// The demo links to in-page anchors so it never navigates away. Use route
// paths ("/", "/works", ...) as keys in a real app.
const DEFAULT_NAV_ITEMS: Record<string, NavItem> = {
  "#home": { name: "Home" },
  "#work": { name: "Work" },
  "#notes": { name: "Notes" },
  "#blog": { name: "Blog" },
  "#about": { name: "About" },
};

/** Gap opened on each side of the active link, in px. */
const SPLIT = 8;
/** Gap a hovered link opens around itself, in px. */
const HOVER_SPLIT = 2;
/** Movement before a press turns into a scrub, in px. */
const DRAG_SLOP = 4;
/** Seconds of release velocity added to where a flick lands. */
const PROJECTION = 0.16;
/** Pointer samples older than this (ms) do not count toward release velocity. */
const VELOCITY_WINDOW = 90;
/** Page scroll past which `compact` folds the bar, in px. */
const COMPACT_AFTER = 80;
const CHEVRON_SIZE = 36;
const CHEVRON_GAP = 4;

const SPRING = { type: "spring", bounce: 0.15, visualDuration: 0.32 } as const;

const round2 = (v: number) => Math.round(v * 100) / 100;
const clamp = (v: number, min: number, max: number) =>
  Math.min(max, Math.max(min, v));

const matchesPath = (path: string, current: string) =>
  path === current || (path !== "/" && current.startsWith(`${path}/`));

/** The longest item path that matches, so "/docs/a" beats "/docs". */
const findItemPath = (paths: string[], current: string | null) => {
  let match: string | undefined;
  for (const path of paths) {
    if (
      current &&
      matchesPath(path, current) &&
      (!match || path.length > match.length)
    ) {
      match = path;
    }
  }
  return match;
};

/** How much link `k` is "the split one" when the split sits at `focus`. */
const bump = (focus: number, k: number) => Math.max(0, 1 - Math.abs(focus - k));

/**
 * x offset of every link for a split centred on `focus`, which may be
 * fractional while scrubbing. Offsets are centred so the bar grows evenly on
 * both sides.
 */
const splitOffsets = (count: number, focus: number, hover: number | null) => {
  const cumulative = [0];
  let total = 0;
  for (let joint = 0; joint < count - 1; joint++) {
    let gap = SPLIT * Math.max(bump(focus, joint), bump(focus, joint + 1));
    const hoverJoint =
      hover !== null &&
      hover !== Math.round(focus) &&
      (joint === hover - 1 || joint === hover);
    if (hoverJoint) {
      gap = Math.max(gap, HOVER_SPLIT);
    }
    total += gap;
    cumulative.push(total);
  }
  return cumulative.map((x) => round2(x - total / 2));
};

interface BarLayout {
  centers: number[];
  widths: number[];
  rowWidth: number;
}

/**
 * Folded: the active link slides to the middle with the chevron beside it,
 * the rest tuck in behind it.
 */
const foldedOffsets = (layout: BarLayout, active: number) => {
  const { centers, widths, rowWidth } = layout;
  const activeWidth = widths[active] ?? 0;
  const groupWidth = activeWidth + CHEVRON_GAP + CHEVRON_SIZE;
  const activeCenter = rowWidth / 2 - groupWidth / 2 + activeWidth / 2;
  const xs = centers.map((center) => round2(activeCenter - center));
  const chevron = round2(
    activeCenter + activeWidth / 2 + CHEVRON_GAP + CHEVRON_SIZE / 2
  );
  return { xs, chevron };
};

/** Fractional link index under a row-local x, from the links' centres. */
const indexAt = (centers: number[], x: number) => {
  const last = centers.length - 1;
  if (last <= 0 || x <= (centers[0] ?? 0)) {
    return 0;
  }
  for (let k = 0; k < last; k++) {
    const a = centers[k] ?? 0;
    const b = centers[k + 1] ?? a;
    if (x < b) {
      return k + (x - a) / Math.max(1, b - a);
    }
  }
  return last;
};

interface DragState {
  pointerId: number;
  startX: number;
  rowLeft: number;
  scrubbing: boolean;
  focus: number;
  samples: { x: number; t: number }[];
}

const releaseVelocity = (samples: DragState["samples"], now: number) => {
  const recent = samples.filter((s) => now - s.t <= VELOCITY_WINDOW);
  const first = recent[0];
  const last = recent.at(-1);
  if (!(first && last) || last.t === first.t) {
    return 0;
  }
  return ((last.x - first.x) / (last.t - first.t)) * 1000;
};

/** A square patch that hides a rounded corner while the neighbour touches. */
const capScale = (gap: number, fold: number) =>
  `scaleX(${round2(clamp(1 - gap / 1.5, 0, 1) * (1 - clamp(fold * 4, 0, 1)))})`;

/** Where each key sends keyboard focus, from index `i` of `n` links. */
const KEY_MOVES: Record<string, (i: number, n: number) => number> = {
  ArrowLeft: (i) => i - 1,
  ArrowRight: (i) => i + 1,
  Home: () => 0,
  End: (_, n) => n - 1,
};

const SURFACE = "bg-zinc-900 dark:bg-zinc-100";
const FOCUS_RING =
  "outline-none focus-visible:ring-2 focus-visible:ring-orange-500 focus-visible:ring-inset";

/**
 * In-page anchors scroll to their target and record the hash with
 * pushState. A native fragment navigation fires popstate, which routers
 * that animate page changes (view transitions) treat as a new page, and
 * re-clicking the current hash never settles one. A hash with no element
 * (like the demo's) only moves the split.
 */
const followHash = (event: MouseEvent<HTMLAnchorElement>, href: string) => {
  if (
    event.defaultPrevented ||
    event.metaKey ||
    event.ctrlKey ||
    event.shiftKey ||
    event.altKey
  ) {
    return;
  }
  event.preventDefault();
  const target = document.getElementById(decodeURIComponent(href.slice(1)));
  if (!target) {
    return;
  }
  target.scrollIntoView();
  if (window.location.hash !== href) {
    window.history.pushState(null, "", href);
  }
};

function ChevronIcon() {
  return (
    <svg
      aria-hidden="true"
      className="size-4"
      fill="none"
      stroke="currentColor"
      strokeLinecap="round"
      strokeLinejoin="round"
      strokeWidth={2}
      viewBox="0 0 24 24"
    >
      <path d="m6 9 6 6 6-6" />
    </svg>
  );
}

interface SegmentProps {
  href: string;
  name: string;
  x: MotionValue<number>;
  prevX?: MotionValue<number>;
  nextX?: MotionValue<number>;
  fold: MotionValue<number>;
  /** Stays visible when the bar folds. */
  pinned: boolean;
  hidden: boolean;
  highlighted: boolean;
  current: boolean;
  linkRef: Ref<HTMLAnchorElement>;
  onSelect: () => void;
  onFocus: (event: FocusEvent<HTMLAnchorElement>) => void;
  onHover: (event: PointerEvent<HTMLDivElement>, entering: boolean) => void;
}

function Segment({
  href,
  name,
  x,
  prevX,
  nextX,
  fold,
  pinned,
  hidden,
  highlighted,
  current,
  linkRef,
  onSelect,
  onFocus,
  onHover,
}: SegmentProps) {
  const transform = useTransform(() => `translate3d(${x.get()}px,0,0)`);
  const opacity = useTransform(() =>
    pinned ? 1 : round2(clamp(1 - fold.get() * 1.8, 0, 1))
  );
  const leftCap = useTransform(() =>
    prevX ? capScale(x.get() - prevX.get(), fold.get()) : "scaleX(0)"
  );
  const rightCap = useTransform(() =>
    nextX ? capScale(nextX.get() - x.get(), fold.get()) : "scaleX(0)"
  );
  // Next's Link scrolls the page when a hash matches no element, so in-page
  // anchors use a plain <a>, handled by `followHash`.
  const isHash = href.startsWith("#");
  const NavLink = isHash ? "a" : Link;

  return (
    <motion.div
      className={cn(
        "relative",
        pinned ? "z-20" : "z-10",
        hidden && "pointer-events-none"
      )}
      onPointerEnter={(event) => onHover(event, true)}
      onPointerLeave={(event) => onHover(event, false)}
      style={{ transform, opacity }}
    >
      <NavLink
        aria-current={current ? "page" : undefined}
        className={cn(
          "relative flex h-9 items-center rounded-xl px-4 font-medium text-sm transition-colors duration-150",
          SURFACE,
          FOCUS_RING,
          highlighted
            ? "text-white dark:text-zinc-950"
            : "text-zinc-400 hover:text-zinc-100 dark:text-zinc-500 dark:hover:text-zinc-800"
        )}
        draggable={false}
        href={href}
        inert={hidden}
        onClick={(event: MouseEvent<HTMLAnchorElement>) => {
          onSelect();
          if (isHash) {
            followHash(event, href);
          }
        }}
        onDragStart={(event: MouseEvent) => event.preventDefault()}
        onFocus={onFocus}
        ref={linkRef}
      >
        {prevX ? (
          <motion.span
            aria-hidden="true"
            className={cn(
              "absolute inset-y-0 -left-px w-3 origin-left",
              SURFACE
            )}
            style={{ transform: leftCap }}
          />
        ) : null}
        {nextX ? (
          <motion.span
            aria-hidden="true"
            className={cn(
              "absolute inset-y-0 -right-px w-3 origin-right",
              SURFACE
            )}
            style={{ transform: rightCap }}
          />
        ) : null}
        <span className="relative">{name}</span>
        <span
          aria-hidden="true"
          className={cn(
            "absolute bottom-1.5 left-1/2 h-0.5 w-3 -translate-x-1/2 rounded-full bg-orange-500 transition-transform duration-200 ease-[cubic-bezier(0.23,1,0.32,1)] motion-reduce:transition-none",
            highlighted ? "scale-x-100" : "scale-x-0"
          )}
        />
      </NavLink>
    </motion.div>
  );
}

/** True once the page has scrolled past `COMPACT_AFTER`, when enabled. */
function useScrolledPast(enabled: boolean) {
  const [past, setPast] = useState(false);
  useEffect(() => {
    if (!enabled) {
      setPast(false);
      return;
    }
    let frame = 0;
    const update = () => {
      frame = 0;
      setPast(window.scrollY > COMPACT_AFTER);
    };
    const onScroll = () => {
      if (!frame) {
        frame = requestAnimationFrame(update);
      }
    };
    update();
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => {
      window.removeEventListener("scroll", onScroll);
      cancelAnimationFrame(frame);
    };
  }, [enabled]);
  return past;
}

/** Opened by the chevron; folds again after another `COMPACT_AFTER` of scroll. */
function useUserOpen(scrolledPast: boolean) {
  const [openedAt, setOpenedAt] = useState<number | null>(null);
  useEffect(() => {
    if (openedAt === null) {
      return;
    }
    const onScroll = () => {
      if (Math.abs(window.scrollY - openedAt) > COMPACT_AFTER) {
        setOpenedAt(null);
      }
    };
    window.addEventListener("scroll", onScroll, { passive: true });
    return () => window.removeEventListener("scroll", onScroll);
  }, [openedAt]);
  if (!scrolledPast && openedAt !== null) {
    setOpenedAt(null);
  }
  return [openedAt !== null, () => setOpenedAt(window.scrollY)] as const;
}

export function MorphicNavbar({
  items = DEFAULT_NAV_ITEMS,
  defaultPath,
  compact = false,
  className,
}: MorphicNavbarProps) {
  const entries = Object.entries(items);
  const paths = entries.map(([path]) => path);
  const count = entries.length;
  const pathname = usePathname();
  const [activePath, setActivePath] = useState(
    () => findItemPath(paths, pathname) ?? defaultPath ?? paths[0] ?? "/"
  );

  // Follow the route when it changes to one of the items, so the active link
  // stays right after the back button or navigation from elsewhere. Clicks
  // still update it right away. In-page anchors (the demo) never match.
  const [syncedPathname, setSyncedPathname] = useState(pathname);
  if (pathname !== syncedPathname) {
    setSyncedPathname(pathname);
    const routePath = findItemPath(paths, pathname);
    if (routePath) {
      setActivePath(routePath);
    }
  }

  const activeIndex = paths.indexOf(findItemPath(paths, activePath) ?? "");
  /** Where a scrub or keyboard focus has moved the split, before committing. */
  const [previewIndex, setPreviewIndex] = useState<number | null>(null);
  const [hoverIndex, setHoverIndex] = useState<number | null>(null);
  const [keyboardInside, setKeyboardInside] = useState(false);
  const [scrubbing, setScrubbing] = useState(false);

  const scrolledPast = useScrolledPast(compact);
  const [userOpen, openBar] = useUserOpen(scrolledPast);
  const folded =
    compact &&
    scrolledPast &&
    !userOpen &&
    !keyboardInside &&
    !scrubbing &&
    activeIndex >= 0;

  const highlightIndex = previewIndex ?? activeIndex;

  // One spring-driven offset per link, rebuilt only when the count changes.
  // biome-ignore lint/correctness/useExhaustiveDependencies: the first split only seeds new values; later moves animate them
  const xs = useMemo(
    () => splitOffsets(count, activeIndex, null).map((x) => motionValue(x)),
    [count]
  );
  const fold = useMotionValue(0);
  const chevronX = useMotionValue(0);
  const chevronTransform = useTransform(
    () => `translate3d(${chevronX.get()}px,0,0)`
  );

  const rowRef = useRef<HTMLDivElement>(null);
  const linkRefs = useRef<(HTMLAnchorElement | null)[]>([]);
  const layoutRef = useRef<BarLayout | null>(null);
  const dragRef = useRef<DragState | null>(null);
  const instantRef = useRef(false);
  const suppressClickRef = useRef(false);
  const reduceMotion = useReducedMotion();
  const reduceRef = useRef(false);
  reduceRef.current = reduceMotion === true;

  const live = { activeIndex, highlightIndex, hoverIndex, folded, count };
  const liveRef = useRef(live);
  liveRef.current = live;

  // Measures the links' natural (untransformed) positions.
  useEffect(() => {
    const row = rowRef.current;
    if (!row) {
      return;
    }
    const measure = () => {
      const boxes = linkRefs.current
        .slice(0, count)
        .map((el) => el?.parentElement);
      layoutRef.current = {
        centers: boxes.map((box) =>
          box ? box.offsetLeft + box.offsetWidth / 2 : 0
        ),
        widths: boxes.map((box) => box?.offsetWidth ?? 0),
        rowWidth: row.offsetWidth,
      };
    };
    measure();
    const observer = new ResizeObserver(measure);
    observer.observe(row);
    return () => observer.disconnect();
  }, [count]);

  /** Sends every offset towards where the current state says it belongs. */
  const retargetRef = useRef<(instant: boolean) => void>(() => undefined);
  retargetRef.current = (instant) => {
    const state = liveRef.current;
    const drag = dragRef.current;
    const jump = instant || reduceRef.current;
    const to = (value: MotionValue<number>, target: number) => {
      if (jump) {
        value.jump(target);
      } else {
        animate(value, target, SPRING);
      }
    };
    const layout = layoutRef.current;
    let targets: number[];
    let chevron: number;
    if (state.folded && layout) {
      const result = foldedOffsets(layout, state.activeIndex);
      targets = result.xs;
      chevron = result.chevron;
    } else {
      const focus = drag?.scrubbing ? drag.focus : state.highlightIndex;
      targets = splitOffsets(
        state.count,
        focus,
        drag?.scrubbing ? null : state.hoverIndex
      );
      // Unfolded, the chevron waits tucked behind the active link.
      const anchor = Math.max(0, state.activeIndex);
      chevron = (layout?.centers[anchor] ?? 0) + (targets[anchor] ?? 0);
    }
    for (const [i, value] of xs.entries()) {
      to(value, targets[i] ?? 0);
    }
    to(chevronX, round2(chevron - CHEVRON_SIZE / 2));
    to(fold, state.folded ? 1 : 0);
  };

  // biome-ignore lint/correctness/useExhaustiveDependencies: these are the inputs retarget reads through liveRef
  useEffect(() => {
    retargetRef.current(instantRef.current);
    instantRef.current = false;
  }, [activeIndex, highlightIndex, hoverIndex, folded, count]);

  const selectIndex = (index: number) => {
    const path = paths[index];
    if (path !== undefined) {
      setActivePath(path);
    }
  };

  const toFocus = (clientX: number, drag: DragState) =>
    clamp(
      indexAt(layoutRef.current?.centers ?? [], clientX - drag.rowLeft),
      0,
      count - 1
    );

  const onPointerDown = (event: PointerEvent<HTMLDivElement>) => {
    const target = event.target as HTMLElement;
    if (event.button !== 0 || folded || target.closest("[data-chevron]")) {
      return;
    }
    dragRef.current = {
      pointerId: event.pointerId,
      startX: event.clientX,
      rowLeft: event.currentTarget.getBoundingClientRect().left,
      scrubbing: false,
      focus: highlightIndex,
      samples: [{ x: event.clientX, t: event.timeStamp }],
    };
  };

  const onPointerMove = (event: PointerEvent<HTMLDivElement>) => {
    const drag = dragRef.current;
    if (!drag || drag.pointerId !== event.pointerId) {
      return;
    }
    if (!drag.scrubbing) {
      if (Math.abs(event.clientX - drag.startX) < DRAG_SLOP) {
        return;
      }
      drag.scrubbing = true;
      event.currentTarget.setPointerCapture(event.pointerId);
      setScrubbing(true);
      setHoverIndex(null);
    }
    drag.samples.push({ x: event.clientX, t: event.timeStamp });
    if (drag.samples.length > 12) {
      drag.samples.shift();
    }
    drag.focus = toFocus(event.clientX, drag);
    setPreviewIndex(Math.round(drag.focus));
    retargetRef.current(false);
  };

  const endDrag = (event: PointerEvent<HTMLDivElement>, commit: boolean) => {
    const drag = dragRef.current;
    if (!drag || drag.pointerId !== event.pointerId) {
      return;
    }
    dragRef.current = null;
    if (!drag.scrubbing) {
      return;
    }
    setScrubbing(false);
    setPreviewIndex(null);
    if (!commit) {
      retargetRef.current(false);
      return;
    }
    // A flick lands where its velocity would carry it, so it can skip links.
    const velocity = releaseVelocity(drag.samples, event.timeStamp);
    const index = Math.round(
      toFocus(event.clientX + velocity * PROJECTION, drag)
    );
    // The browser still sends a click for this press; swallow it and fire
    // the chosen link's own click so Next's router (or the anchor) handles it.
    suppressClickRef.current = true;
    setTimeout(() => {
      suppressClickRef.current = false;
    }, 0);
    selectIndex(index);
    linkRefs.current[index]?.click();
  };

  const onClickCapture = (event: MouseEvent<HTMLDivElement>) => {
    if (suppressClickRef.current && event.isTrusted) {
      suppressClickRef.current = false;
      event.preventDefault();
      event.stopPropagation();
    }
  };

  const onKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    const move = KEY_MOVES[event.key];
    const from = linkRefs.current.indexOf(
      document.activeElement as HTMLAnchorElement
    );
    if (!move || from < 0) {
      return;
    }
    event.preventDefault();
    const next = clamp(move(from, count), 0, count - 1);
    instantRef.current = true;
    setPreviewIndex(next);
    linkRefs.current[next]?.focus();
  };

  const onLinkFocus = (index: number, event: FocusEvent<HTMLAnchorElement>) => {
    if (event.currentTarget.matches(":focus-visible")) {
      // Keyboard moves are instant: no spring for something done this often.
      instantRef.current = true;
      setKeyboardInside(true);
      setPreviewIndex(index);
    }
  };

  const onRowBlur = (event: FocusEvent<HTMLDivElement>) => {
    if (!event.currentTarget.contains(event.relatedTarget as Node | null)) {
      instantRef.current = true;
      setKeyboardInside(false);
      setPreviewIndex(null);
    }
  };

  const onHover = (
    index: number,
    event: PointerEvent<HTMLDivElement>,
    entering: boolean
  ) => {
    if (event.pointerType !== "mouse" || dragRef.current?.scrubbing) {
      return;
    }
    setHoverIndex((current) => {
      if (entering) {
        return index;
      }
      return current === index ? null : current;
    });
  };

  const openFolded = () => {
    openBar();
    linkRefs.current[activeIndex]?.focus({ preventScroll: true });
  };

  return (
    <nav
      aria-label="Main"
      className={cn("flex justify-center px-4 py-2", className)}
    >
      {/* biome-ignore lint/a11y/noNoninteractiveElementInteractions: the row only adds scrubbing and arrow keys on top of real links */}
      {/* biome-ignore lint/a11y/noStaticElementInteractions: same as above */}
      <div
        className="relative flex touch-pan-y select-none items-center"
        onBlur={onRowBlur}
        onClickCapture={onClickCapture}
        onKeyDown={onKeyDown}
        onPointerCancel={(event) => endDrag(event, false)}
        onPointerDown={onPointerDown}
        onPointerMove={onPointerMove}
        onPointerUp={(event) => endDrag(event, true)}
        ref={rowRef}
      >
        {entries.map(([path, { name }], index) => (
          <Segment
            current={index === activeIndex}
            fold={fold}
            hidden={folded && index !== activeIndex}
            highlighted={index === highlightIndex}
            href={path}
            key={`${count}-${path}`}
            linkRef={(el) => {
              linkRefs.current[index] = el;
            }}
            name={name}
            nextX={xs[index + 1]}
            onFocus={(event) => onLinkFocus(index, event)}
            onHover={(event, entering) => onHover(index, event, entering)}
            onSelect={() => selectIndex(index)}
            pinned={index === activeIndex}
            prevX={xs[index - 1]}
            x={xs[index] ?? fold}
          />
        ))}
        {compact ? (
          <motion.button
            aria-expanded={!folded}
            aria-hidden={!folded}
            aria-label="Show all links"
            className={cn(
              "absolute top-0 left-0 flex size-9 items-center justify-center rounded-xl text-zinc-400 transition-colors duration-150 hover:text-zinc-100 dark:text-zinc-500 dark:hover:text-zinc-800",
              SURFACE,
              FOCUS_RING,
              folded ? "z-30" : "pointer-events-none z-0"
            )}
            data-chevron=""
            onClick={openFolded}
            style={{ transform: chevronTransform, opacity: fold }}
            tabIndex={folded ? 0 : -1}
            type="button"
          >
            <ChevronIcon />
          </motion.button>
        ) : null}
      </div>
    </nav>
  );
}

export default MorphicNavbar;
```


---

# Account Menu
> An account card that morphs into its own menu, with account switching, status, theme and hold-to-sign-out.

Source: https://kokonutui.com/docs/navigation/profile-dropdown

## Installation

```bash
npx shadcn@latest add @kokonutui/profile-dropdown
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Account Menu
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  Check,
  ChevronLeft,
  ChevronRight,
  ChevronsUpDown,
  CreditCard,
  LogOut,
  Monitor,
  Moon,
  Plus,
  Settings,
  Sun,
  User,
} from "lucide-react";
import {
  animate,
  motion,
  type Transition,
  useMotionTemplate,
  useMotionValue,
  useReducedMotion,
} from "motion/react";
import {
  type HTMLAttributes,
  type KeyboardEvent,
  type MouseEvent,
  type PointerEvent,
  type ReactNode,
  useEffect,
  useId,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface Account {
  id: string;
  name: string;
  email: string;
  /** Shown in the avatar. Defaults to the first letters of `name`. */
  initials?: string;
  /** Plain label shown in the menu header, such as "Pro". */
  plan?: string;
}

export type AccountStatus = "online" | "away" | "busy";
export type AccountTheme = "light" | "dark" | "system";

export interface ProfileMenuItem {
  label: string;
  icon?: ReactNode;
  /** Quiet text on the right, such as a plan name or a shortcut. */
  value?: string;
  /** Renders the item as a link. Without it the item is a button. */
  href?: string;
  /** Opens `href` in a new tab. */
  external?: boolean;
  onSelect?: () => void;
}

interface ProfileDropdownProps
  extends Omit<HTMLAttributes<HTMLDivElement>, "onChange"> {
  accounts?: Account[];
  defaultAccountId?: string;
  onAccountChange?: (account: Account) => void;
  onAddAccount?: () => void;
  /** Menu entries between the settings rows and Switch account. */
  items?: ProfileMenuItem[];
  /** Controlled theme. Leave it out to keep the choice in local state. */
  theme?: AccountTheme;
  defaultTheme?: AccountTheme;
  onThemeChange?: (theme: AccountTheme) => void;
  status?: AccountStatus;
  defaultStatus?: AccountStatus;
  onStatusChange?: (status: AccountStatus) => void;
  /** Called once Sign out has been held for `holdDuration` ms. */
  onSignOut?: () => void;
  holdDuration?: number;
}

const SAMPLE_ACCOUNTS: Account[] = [
  { id: "personal", name: "Maya Ortega", email: "maya@ortega.me", plan: "Pro" },
  {
    id: "studio",
    name: "Fieldwork Studio",
    email: "team@fieldwork.studio",
    plan: "Team",
  },
  {
    id: "side",
    name: "Night Shift",
    email: "hello@nightshift.dev",
    plan: "Free",
  },
];

const SAMPLE_ITEMS: ProfileMenuItem[] = [
  { label: "Profile", icon: <User className="size-4" /> },
  { label: "Settings", icon: <Settings className="size-4" />, value: "⌘," },
  { label: "Billing", icon: <CreditCard className="size-4" /> },
];

const STATUSES: {
  id: AccountStatus;
  label: string;
  name: string;
  dot: string;
}[] = [
  { id: "online", label: "Online", name: "Online", dot: "bg-emerald-500" },
  { id: "away", label: "Away", name: "Away", dot: "bg-amber-400" },
  { id: "busy", label: "DND", name: "Do not disturb", dot: "bg-red-500" },
];

const THEMES = [
  { id: "light", label: "Light", Icon: Sun },
  { id: "dark", label: "Dark", Icon: Moon },
  { id: "system", label: "System", Icon: Monitor },
] as const;

const AVATAR_TONES = [
  "bg-zinc-900 text-white dark:bg-zinc-100 dark:text-zinc-900",
  "bg-zinc-200 text-zinc-700 dark:bg-zinc-700 dark:text-zinc-100",
  "bg-zinc-100 text-zinc-500 ring-1 ring-zinc-200 ring-inset dark:bg-zinc-800 dark:text-zinc-300 dark:ring-zinc-700",
];

const WHITESPACE = /\s+/;
const PANEL_W = 288;
const RADIUS = 16;
const SPRING: Transition = { type: "spring", duration: 0.3, bounce: 0 };
const INDICATOR_SPRING: Transition = {
  type: "spring",
  duration: 0.25,
  bounce: 0,
};
const INSTANT: Transition = { duration: 0 };
const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const NAV_KEYS = new Set([
  "ArrowDown",
  "ArrowUp",
  "ArrowLeft",
  "ArrowRight",
  "Home",
  "End",
]);

const ITEM_CLASS =
  "flex w-full cursor-default items-center gap-2.5 rounded-[10px] px-2.5 py-2 text-left text-sm text-zinc-700 outline-none transition-colors duration-100 focus:bg-zinc-100 focus:text-zinc-950 dark:text-zinc-300 dark:focus:bg-zinc-800 dark:focus:text-zinc-50";

type Phase = "closed" | "open" | "closing";
type Page = "main" | "accounts";
type Via = "pointer" | "keyboard";

function initialsOf(account: Account) {
  if (account.initials) {
    return account.initials;
  }
  return account.name
    .split(WHITESPACE)
    .slice(0, 2)
    .map((part) => part[0] ?? "")
    .join("")
    .toUpperCase();
}

function viaOf(event: MouseEvent): Via {
  // A click fired by Enter or Space carries no pointer detail.
  return event.detail === 0 ? "keyboard" : "pointer";
}

function menuItems(root: HTMLElement | null) {
  if (!root) {
    return [];
  }
  return Array.from(root.querySelectorAll<HTMLElement>("[data-menu-item]"));
}

function sideTarget(items: HTMLElement[], current: HTMLElement, step: number) {
  const row = items.filter((item) => item.dataset.row === current.dataset.row);
  if (row.length < 2) {
    return;
  }
  const index = row.indexOf(current);
  return row[(index + step + row.length) % row.length];
}

function rowTarget(items: HTMLElement[], current: HTMLElement, step: number) {
  const rows = [...new Set(items.map((item) => item.dataset.row))];
  const index = rows.indexOf(current.dataset.row);
  const next = rows[(index + step + rows.length) % rows.length];
  const candidates = items.filter((item) => item.dataset.row === next);
  return (
    candidates.find((item) => item.getAttribute("aria-checked") === "true") ??
    candidates[0]
  );
}

/** Where arrow keys move focus: rows go up and down, radios left and right. */
function nextTarget(
  items: HTMLElement[],
  active: Element | null,
  key: string
): HTMLElement | undefined {
  if (key === "Home") {
    return items[0];
  }
  if (key === "End") {
    return items.at(-1);
  }
  const current = items.find((item) => item === active);
  if (!current) {
    return key === "ArrowUp" ? items.at(-1) : items[0];
  }
  if (key === "ArrowLeft" || key === "ArrowRight") {
    return sideTarget(items, current, key === "ArrowRight" ? 1 : -1);
  }
  return rowTarget(items, current, key === "ArrowDown" ? 1 : -1);
}

function useControllable<T>(
  value: T | undefined,
  fallback: T,
  onChange?: (next: T) => void
) {
  const [local, setLocal] = useState(fallback);
  const set = (next: T) => {
    setLocal(next);
    onChange?.(next);
  };
  return [value ?? local, set] as const;
}

function Avatar({
  account,
  tone,
  status,
  className,
}: {
  account: Account;
  tone: number;
  status?: AccountStatus;
  className?: string;
}) {
  const dot = STATUSES.find((entry) => entry.id === status)?.dot;
  return (
    <span
      aria-hidden="true"
      className={cn(
        "relative grid shrink-0 select-none place-items-center rounded-full font-medium text-[11px] tracking-wide",
        AVATAR_TONES[tone % AVATAR_TONES.length],
        className
      )}
    >
      {initialsOf(account)}
      {dot ? (
        <span
          className={cn(
            "absolute right-0 bottom-0 size-2.5 rounded-full ring-2 ring-white transition-colors duration-200 dark:ring-zinc-900",
            dot
          )}
        />
      ) : null}
    </span>
  );
}

/**
 * The avatar, name and email. Rendered in the trigger while the menu is
 * closed and in the menu header while it is open; shared layout ids let the
 * three pieces travel between the two places.
 */
function Identity({
  uid,
  shared,
  account,
  tone,
  status,
  transition,
  stacked,
}: {
  uid: string;
  shared: boolean;
  account: Account;
  tone: number;
  status: AccountStatus;
  transition: Transition;
  stacked: boolean;
}) {
  const hidden = shared ? undefined : "invisible";
  return (
    <span
      className={cn(
        "flex min-w-0",
        stacked ? "flex-col items-start gap-3" : "items-center gap-2.5"
      )}
    >
      <motion.span
        className={cn("relative z-20 block", hidden)}
        key={shared ? "avatar-shared" : "avatar-static"}
        layoutId={shared ? `${uid}-avatar` : undefined}
        transition={transition}
      >
        <Avatar
          account={account}
          className={stacked ? "size-10" : "size-8"}
          status={status}
          tone={tone}
        />
      </motion.span>
      <span className="flex min-w-0 flex-col text-left">
        <motion.span
          className={cn(
            "relative z-20 block truncate font-medium text-sm text-zinc-900 leading-5 dark:text-zinc-100",
            hidden
          )}
          key={shared ? "name-shared" : "name-static"}
          layoutId={shared ? `${uid}-name` : undefined}
          transition={transition}
        >
          {account.name}
        </motion.span>
        <motion.span
          className={cn(
            "relative z-20 block truncate text-xs text-zinc-500 leading-4 dark:text-zinc-400",
            hidden
          )}
          key={shared ? "email-shared" : "email-static"}
          layoutId={shared ? `${uid}-email` : undefined}
          transition={transition}
        >
          {account.email}
        </motion.span>
      </span>
    </span>
  );
}

function Separator() {
  return (
    <hr className="mx-2.5 my-1.5 h-px border-0 bg-zinc-100 dark:bg-zinc-800" />
  );
}

function HoldSignOut({
  duration,
  onComplete,
}: {
  duration: number;
  onComplete: (via: Via) => void;
}) {
  const [holding, setHolding] = useState(false);
  const [done, setDone] = useState(false);
  const [nudge, setNudge] = useState(false);
  const timer = useRef<number | undefined>(undefined);
  const nudgeTimer = useRef<number | undefined>(undefined);

  useEffect(
    () => () => {
      window.clearTimeout(timer.current);
      window.clearTimeout(nudgeTimer.current);
    },
    []
  );

  const start = (via: Via) => {
    if (timer.current !== undefined || done) {
      return;
    }
    window.clearTimeout(nudgeTimer.current);
    setNudge(false);
    setHolding(true);
    timer.current = window.setTimeout(() => {
      timer.current = undefined;
      setHolding(false);
      setDone(true);
      onComplete(via);
    }, duration);
  };

  const cancel = () => {
    if (timer.current === undefined) {
      return;
    }
    window.clearTimeout(timer.current);
    timer.current = undefined;
    setHolding(false);
    setNudge(true);
    nudgeTimer.current = window.setTimeout(() => setNudge(false), 1400);
  };

  const label = (
    <>
      <LogOut className="size-4" />
      <span className="flex-1">Sign out</span>
      <span className="text-xs opacity-60">
        {nudge ? "Keep holding" : "Hold"}
      </span>
    </>
  );

  return (
    <button
      className={cn(ITEM_CLASS, "relative touch-none select-none")}
      data-menu-item=""
      data-row="sign-out"
      onBlur={cancel}
      onClick={(event) => event.preventDefault()}
      onContextMenu={(event) => event.preventDefault()}
      onKeyDown={(event) => {
        if (event.key === "Enter" || event.key === " ") {
          event.preventDefault();
          if (!event.repeat) {
            start("keyboard");
          }
        }
      }}
      onKeyUp={(event) => {
        if (event.key === "Enter" || event.key === " ") {
          event.preventDefault();
          cancel();
        }
      }}
      onPointerCancel={cancel}
      onPointerDown={(event) => {
        if (event.button !== 0) {
          return;
        }
        event.currentTarget.setPointerCapture(event.pointerId);
        start("pointer");
      }}
      onPointerUp={cancel}
      role="menuitem"
      tabIndex={-1}
      type="button"
    >
      {label}
      <span className="sr-only">, press and hold to confirm</span>
      {/* The fill: an inverted copy of the row, revealed left to right. */}
      <span
        aria-hidden="true"
        className="absolute inset-0 flex items-center gap-2.5 rounded-[10px] bg-zinc-900 px-2.5 text-zinc-50 dark:bg-zinc-100 dark:text-zinc-900"
        style={{
          clipPath:
            holding || done
              ? "inset(0 0 0 0 round 10px)"
              : "inset(0 100% 0 0 round 10px)",
          transition: holding
            ? `clip-path ${duration}ms linear`
            : "clip-path 240ms cubic-bezier(0.23, 1, 0.32, 1)",
        }}
      >
        {label}
      </span>
    </button>
  );
}

function StatusRow({
  status,
  onChange,
}: {
  status: AccountStatus;
  onChange: (status: AccountStatus) => void;
}) {
  return (
    <fieldset
      aria-label="Status"
      className="m-0 flex min-w-0 items-center justify-between border-0 py-1 pr-1 pl-2.5"
    >
      <span className="text-sm text-zinc-500 dark:text-zinc-400">Status</span>
      <span className="flex">
        {STATUSES.map((entry) => {
          const checked = entry.id === status;
          return (
            <button
              aria-checked={checked}
              aria-label={entry.name}
              className="flex items-center gap-1.5 rounded-lg px-2 py-1.5 text-xs text-zinc-500 outline-none transition-colors duration-100 focus:bg-zinc-100 aria-checked:text-zinc-900 dark:text-zinc-400 dark:aria-checked:text-zinc-100 dark:focus:bg-zinc-800"
              data-menu-item=""
              data-row="status"
              key={entry.id}
              onClick={() => onChange(entry.id)}
              role="menuitemradio"
              tabIndex={-1}
              type="button"
            >
              <span
                className={cn(
                  "size-2 rounded-full transition-colors duration-200",
                  checked ? entry.dot : "bg-zinc-300 dark:bg-zinc-600"
                )}
              />
              {entry.label}
            </button>
          );
        })}
      </span>
    </fieldset>
  );
}

function ThemeRow({
  uid,
  theme,
  onChange,
  reduced,
}: {
  uid: string;
  theme: AccountTheme;
  onChange: (theme: AccountTheme) => void;
  reduced: boolean;
}) {
  return (
    <fieldset
      aria-label="Theme"
      className="m-0 flex min-w-0 items-center justify-between border-0 py-1 pr-1 pl-2.5"
    >
      <span className="text-sm text-zinc-500 dark:text-zinc-400">Theme</span>
      <span className="flex rounded-[10px] bg-zinc-100 p-0.5 dark:bg-zinc-800">
        {THEMES.map(({ id, label, Icon }) => {
          const checked = id === theme;
          return (
            <button
              aria-checked={checked}
              aria-label={label}
              className="relative grid h-7 w-9 place-items-center rounded-lg text-zinc-500 outline-none transition-colors duration-150 hover:text-zinc-800 focus-visible:ring-2 focus-visible:ring-zinc-400 aria-checked:text-zinc-900 dark:text-zinc-400 dark:aria-checked:text-zinc-50 dark:hover:text-zinc-200"
              data-menu-item=""
              data-row="theme"
              key={id}
              onClick={() => onChange(id)}
              role="menuitemradio"
              tabIndex={-1}
              type="button"
            >
              {checked ? (
                <motion.span
                  className="absolute inset-0 rounded-lg bg-white shadow-[0_1px_2px_rgb(0_0_0/0.08)] dark:bg-zinc-700"
                  layoutId={`${uid}-theme`}
                  transition={reduced ? INSTANT : INDICATOR_SPRING}
                />
              ) : null}
              <Icon className="relative size-3.5" />
            </button>
          );
        })}
      </span>
    </fieldset>
  );
}

function LinkItem({
  item,
  index,
  onSelect,
}: {
  item: ProfileMenuItem;
  index: number;
  onSelect: (event: MouseEvent, run?: () => void) => void;
}) {
  const inner = (
    <>
      <span className="text-zinc-400 dark:text-zinc-500">{item.icon}</span>
      <span className="flex-1">{item.label}</span>
      {item.value ? (
        <span className="text-xs text-zinc-400 dark:text-zinc-500">
          {item.value}
        </span>
      ) : null}
    </>
  );
  const common = {
    className: ITEM_CLASS,
    "data-menu-item": "",
    "data-row": `item-${index}`,
    onClick: (event: MouseEvent) => onSelect(event, item.onSelect),
    role: "menuitem",
    tabIndex: -1,
  } as const;
  if (item.href) {
    return (
      <a
        {...common}
        href={item.href}
        {...(item.external && { rel: "noopener noreferrer", target: "_blank" })}
      >
        {inner}
      </a>
    );
  }
  return (
    <button {...common} type="button">
      {inner}
    </button>
  );
}

export default function ProfileDropdown({
  accounts = SAMPLE_ACCOUNTS,
  defaultAccountId,
  onAccountChange,
  onAddAccount,
  items = SAMPLE_ITEMS,
  theme: themeProp,
  defaultTheme = "system",
  onThemeChange,
  status: statusProp,
  defaultStatus = "online",
  onStatusChange,
  onSignOut,
  holdDuration = 1200,
  className,
  ...props
}: ProfileDropdownProps) {
  const uid = useId();
  const reduced = useReducedMotion() === true;
  const [phase, setPhase] = useState<Phase>("closed");
  const [instant, setInstant] = useState(false);
  const [page, setPage] = useState<Page>("main");
  const [openSeq, setOpenSeq] = useState(0);
  const [accountId, setAccountId] = useState(
    defaultAccountId ?? accounts[0]?.id
  );
  const [theme, setTheme] = useControllable(
    themeProp,
    defaultTheme,
    onThemeChange
  );
  const [status, setStatus] = useControllable(
    statusProp,
    defaultStatus,
    onStatusChange
  );

  const wrapperRef = useRef<HTMLDivElement>(null);
  const triggerRef = useRef<HTMLButtonElement>(null);
  const mainRef = useRef<HTMLDivElement>(null);
  const accountsRef = useRef<HTMLDivElement>(null);
  const phaseRef = useRef<Phase>("closed");
  phaseRef.current = phase;
  const openIntent = useRef<{
    focus: "first" | "last" | "menu";
    resume: boolean;
  }>({ focus: "menu", resume: false });
  const pageFocus = useRef<"first" | "switch" | null>(null);
  const closeSeq = useRef(0);
  const targetH = useRef(0);

  // The panel's visible box. The two surface layers (border and fill) and the
  // content all clip to it, so the menu grows out of the trigger's own
  // rectangle without any layout work per frame.
  const w = useMotionValue(0);
  const h = useMotionValue(0);
  const pageX = useMotionValue(0);
  const bodyOpacity = useMotionValue(1);
  const outerClip = useMotionTemplate`inset(0px 0px calc(100% - ${h}px) calc(100% - ${w}px) round ${RADIUS}px)`;
  const innerClip = useMotionTemplate`inset(1px 1px calc(100% - ${h}px + 1px) calc(100% - ${w}px + 1px) round ${RADIUS - 1}px)`;
  const pageTransform = useMotionTemplate`translate3d(${pageX}px, 0, 0)`;

  const account = accounts.find((entry) => entry.id === accountId) ??
    accounts[0] ?? { id: "guest", name: "Guest", email: "" };
  const tone = Math.max(0, accounts.indexOf(account));
  const others = accounts.filter((entry) => entry.id !== account.id);
  const sharedTransition = instant ? INSTANT : SPRING;
  const sharedInPanel = phase === "open";
  const menuId = `${uid}-menu`;

  const pageEl = (target: Page) =>
    target === "main" ? mainRef.current : accountsRef.current;

  const openMenu = (via: Via, focus: "first" | "last" | "menu") => {
    if (phaseRef.current === "open") {
      return;
    }
    openIntent.current = { focus, resume: phaseRef.current === "closing" };
    closeSeq.current += 1;
    setInstant(via === "keyboard" || reduced);
    setPage("main");
    setPhase("open");
    setOpenSeq((seq) => seq + 1);
  };

  const closeMenu = (via: Via, returnFocus: boolean) => {
    if (phaseRef.current !== "open") {
      return;
    }
    const trigger = triggerRef.current;
    if (returnFocus) {
      trigger?.focus({ preventScroll: true });
    }
    if (via === "keyboard" || reduced || !trigger) {
      setInstant(true);
      setPhase("closed");
      return;
    }
    setInstant(false);
    setPhase("closing");
    const seq = ++closeSeq.current;
    animate(bodyOpacity, 0, { duration: 0.12, ease: EASE_OUT });
    animate(w, trigger.offsetWidth, SPRING);
    animate(h, trigger.offsetHeight, SPRING).then(() => {
      if (closeSeq.current === seq) {
        setPhase("closed");
      }
    });
  };

  const goTo = (target: Page) => {
    pageFocus.current = target === "accounts" ? "first" : "switch";
    setPage(target);
  };

  const select = (event: MouseEvent, run?: () => void) => {
    run?.();
    closeMenu(viaOf(event), true);
  };

  // Opening: size the clip to the trigger, then spring it out to the menu.
  // A keyboard open skips straight to the end.
  // biome-ignore lint/correctness/useExhaustiveDependencies: runs once per open
  useLayoutEffect(() => {
    const trigger = triggerRef.current;
    const main = mainRef.current;
    if (openSeq === 0 || phaseRef.current !== "open" || !trigger || !main) {
      return;
    }
    pageX.jump(0);
    targetH.current = main.offsetHeight;
    if (instant) {
      w.jump(PANEL_W);
      h.jump(targetH.current);
      bodyOpacity.jump(1);
    } else {
      if (!openIntent.current.resume) {
        w.jump(trigger.offsetWidth);
        h.jump(trigger.offsetHeight);
        bodyOpacity.jump(0);
      }
      animate(w, PANEL_W, SPRING);
      animate(h, targetH.current, SPRING);
      animate(bodyOpacity, 1, { duration: 0.2, delay: 0.05, ease: EASE_OUT });
    }
    const list = menuItems(main);
    const targets = {
      first: list[0],
      last: list.at(-1),
      menu: main.querySelector<HTMLElement>("[role=menu]"),
    };
    targets[openIntent.current.focus]?.focus({ preventScroll: true });
  }, [openSeq]);

  // Switching pages: push sideways and spring the height to the new page.
  // biome-ignore lint/correctness/useExhaustiveDependencies: keyed on page
  useEffect(() => {
    const el = pageEl(page);
    if (phaseRef.current !== "open" || !el) {
      return;
    }
    const x = page === "main" ? 0 : -PANEL_W;
    targetH.current = el.offsetHeight;
    if (reduced) {
      pageX.jump(x);
      h.jump(targetH.current);
    } else {
      animate(pageX, x, SPRING);
      animate(h, targetH.current, SPRING);
    }
    const intent = pageFocus.current;
    pageFocus.current = null;
    if (intent === "first") {
      const list = menuItems(el);
      const checked = list.find(
        (item) => item.getAttribute("aria-checked") === "true"
      );
      (checked ?? list[0])?.focus({ preventScroll: true });
    } else if (intent === "switch") {
      el.querySelector<HTMLElement>("[data-switch]")?.focus({
        preventScroll: true,
      });
    }
  }, [page]);

  // Keep the height in step if a page's content changes size while open.
  // biome-ignore lint/correctness/useExhaustiveDependencies: observers read refs
  useEffect(() => {
    if (phase !== "open") {
      return;
    }
    const observer = new ResizeObserver(() => {
      const el = pageEl(page);
      if (!el || phaseRef.current !== "open") {
        return;
      }
      const next = el.offsetHeight;
      if (Math.abs(next - targetH.current) < 0.5) {
        return;
      }
      targetH.current = next;
      animate(h, next, reduced ? INSTANT : SPRING);
    });
    for (const el of [mainRef.current, accountsRef.current]) {
      if (el) {
        observer.observe(el);
      }
    }
    return () => observer.disconnect();
  }, [phase, page]);

  // A press anywhere outside closes, with the morph.
  // biome-ignore lint/correctness/useExhaustiveDependencies: closeMenu reads refs
  useEffect(() => {
    if (phase !== "open") {
      return;
    }
    const onDown = (event: globalThis.PointerEvent) => {
      if (!wrapperRef.current?.contains(event.target as Node)) {
        closeMenu("pointer", false);
      }
    };
    document.addEventListener("pointerdown", onDown, true);
    return () => document.removeEventListener("pointerdown", onDown, true);
  }, [phase]);

  const onPanelKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    if (event.key === "Escape" || event.key === "Tab") {
      event.preventDefault();
      closeMenu("keyboard", true);
      return;
    }
    if (page === "accounts" && event.key === "Backspace") {
      event.preventDefault();
      goTo("main");
      return;
    }
    if (!NAV_KEYS.has(event.key)) {
      return;
    }
    event.preventDefault();
    const active = document.activeElement;
    const target = nextTarget(menuItems(pageEl(page)), active, event.key);
    if (target) {
      target.focus({ preventScroll: true });
    } else if (page === "accounts" && event.key === "ArrowLeft") {
      goTo("main");
    } else if (
      event.key === "ArrowRight" &&
      active instanceof HTMLElement &&
      active.dataset.switch !== undefined
    ) {
      goTo("accounts");
    }
  };

  // Hovering an item focuses it, so pointer and keyboard share one highlight.
  const onPanelPointerMove = (event: PointerEvent<HTMLDivElement>) => {
    if (event.pointerType !== "mouse") {
      return;
    }
    const item = (event.target as HTMLElement).closest<HTMLElement>(
      "[data-menu-item]"
    );
    if (item && document.activeElement !== item) {
      item.focus({ preventScroll: true });
    }
  };

  return (
    <div
      className={cn(
        "relative isolate inline-block",
        phase !== "closed" && "z-50",
        className
      )}
      ref={wrapperRef}
      {...props}
    >
      <button
        aria-controls={sharedInPanel ? menuId : undefined}
        aria-expanded={sharedInPanel}
        aria-haspopup="menu"
        className="flex w-60 items-center gap-2.5 rounded-2xl border border-zinc-200 bg-white p-2 pr-3 text-left outline-none transition-colors duration-150 hover:border-zinc-300 hover:bg-zinc-50 focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-2 focus-visible:ring-offset-white dark:border-zinc-800 dark:bg-zinc-900 dark:focus-visible:ring-zinc-500 dark:focus-visible:ring-offset-zinc-950 dark:hover:border-zinc-700 dark:hover:bg-zinc-800/60"
        onClick={(event) => {
          const via = viaOf(event);
          openMenu(via, via === "keyboard" ? "first" : "menu");
        }}
        onKeyDown={(event) => {
          if (event.key === "ArrowDown" || event.key === "ArrowUp") {
            event.preventDefault();
            openMenu("keyboard", event.key === "ArrowDown" ? "first" : "last");
          }
        }}
        ref={triggerRef}
        type="button"
      >
        <span className="min-w-0 flex-1">
          <Identity
            account={account}
            shared={!sharedInPanel}
            stacked={false}
            status={status}
            tone={tone}
            transition={sharedTransition}
            uid={uid}
          />
        </span>
        <ChevronsUpDown
          aria-hidden="true"
          className={cn(
            "size-4 shrink-0 text-zinc-400 transition-opacity duration-150 dark:text-zinc-500",
            phase !== "closed" && "opacity-0"
          )}
        />
      </button>

      {phase === "closed" ? null : (
        <div
          className="pointer-events-none absolute top-0 right-0 z-10"
          style={{ width: PANEL_W }}
        >
          <div
            aria-hidden="true"
            className="absolute inset-0 [filter:drop-shadow(0_12px_24px_rgb(0_0_0/0.08))_drop-shadow(0_2px_4px_rgb(0_0_0/0.04))] dark:[filter:drop-shadow(0_12px_28px_rgb(0_0_0/0.5))]"
          >
            <motion.div
              className="absolute inset-0 bg-zinc-200 dark:bg-zinc-800"
              style={{ clipPath: outerClip }}
            />
            <motion.div
              className="absolute inset-0 bg-white dark:bg-zinc-900"
              style={{ clipPath: innerClip }}
            />
          </div>
          <motion.div
            className={cn("relative", sharedInPanel && "pointer-events-auto")}
            onKeyDown={onPanelKeyDown}
            onPointerMove={onPanelPointerMove}
            style={{ clipPath: innerClip }}
          >
            <motion.div
              className="flex w-max items-start"
              style={{ transform: pageTransform }}
            >
              <div
                className={cn(
                  "shrink-0 p-1.5 transition-opacity duration-300 ease-[cubic-bezier(0.23,1,0.32,1)]",
                  page !== "main" && "opacity-0"
                )}
                inert={page !== "main"}
                ref={mainRef}
                style={{ width: PANEL_W }}
              >
                <div className="flex items-start justify-between px-2.5 pt-2.5 pb-3">
                  <Identity
                    account={account}
                    shared={sharedInPanel}
                    stacked
                    status={status}
                    tone={tone}
                    transition={sharedTransition}
                    uid={uid}
                  />
                  {account.plan ? (
                    <motion.span
                      className="shrink-0 pt-0.5 text-xs text-zinc-400 dark:text-zinc-500"
                      style={{ opacity: bodyOpacity }}
                    >
                      {account.plan}
                    </motion.span>
                  ) : null}
                </div>
                <motion.div
                  aria-label={account.name}
                  className="outline-none"
                  id={menuId}
                  role="menu"
                  style={{ opacity: bodyOpacity }}
                  tabIndex={-1}
                >
                  <StatusRow onChange={setStatus} status={status} />
                  <ThemeRow
                    onChange={setTheme}
                    reduced={reduced}
                    theme={theme}
                    uid={uid}
                  />
                  <Separator />
                  {items.map((item, index) => (
                    <LinkItem
                      index={index}
                      item={item}
                      key={item.label}
                      onSelect={select}
                    />
                  ))}
                  {accounts.length > 1 ? (
                    <button
                      aria-expanded={page === "accounts"}
                      aria-haspopup="menu"
                      className={ITEM_CLASS}
                      data-menu-item=""
                      data-row="switch"
                      data-switch=""
                      onClick={() => goTo("accounts")}
                      role="menuitem"
                      tabIndex={-1}
                      type="button"
                    >
                      <span className="flex -space-x-1.5">
                        {others.slice(0, 2).map((entry) => (
                          <Avatar
                            account={entry}
                            className="size-5 text-[7px] tracking-normal ring-2 ring-white dark:ring-zinc-900"
                            key={entry.id}
                            tone={accounts.indexOf(entry)}
                          />
                        ))}
                      </span>
                      <span className="flex-1">Switch account</span>
                      <ChevronRight className="size-4 text-zinc-400 dark:text-zinc-500" />
                    </button>
                  ) : null}
                  <Separator />
                  <HoldSignOut
                    duration={holdDuration}
                    onComplete={(via) => {
                      onSignOut?.();
                      closeMenu(via, true);
                    }}
                  />
                </motion.div>
              </div>

              <div
                className={cn(
                  "shrink-0 p-1.5 transition-opacity duration-300 ease-[cubic-bezier(0.23,1,0.32,1)]",
                  page !== "accounts" && "opacity-0"
                )}
                inert={page !== "accounts"}
                ref={accountsRef}
                style={{ width: PANEL_W }}
              >
                <motion.div
                  aria-label="Switch account"
                  className="outline-none"
                  role="menu"
                  style={{ opacity: bodyOpacity }}
                  tabIndex={-1}
                >
                  <button
                    className={cn(ITEM_CLASS, "gap-1.5 pl-1.5 font-medium")}
                    data-menu-item=""
                    data-row="back"
                    onClick={() => goTo("main")}
                    role="menuitem"
                    tabIndex={-1}
                    type="button"
                  >
                    <ChevronLeft className="size-4 text-zinc-400 dark:text-zinc-500" />
                    <span className="sr-only">Back to </span>
                    Switch account
                  </button>
                  <Separator />
                  {accounts.map((entry, index) => {
                    const checked = entry.id === account.id;
                    return (
                      <button
                        aria-checked={checked}
                        className={ITEM_CLASS}
                        data-menu-item=""
                        data-row={`account-${entry.id}`}
                        key={entry.id}
                        onClick={() => {
                          if (!checked) {
                            setAccountId(entry.id);
                            onAccountChange?.(entry);
                          }
                          goTo("main");
                        }}
                        role="menuitemradio"
                        tabIndex={-1}
                        type="button"
                      >
                        <Avatar
                          account={entry}
                          className="size-7"
                          status={checked ? status : undefined}
                          tone={index}
                        />
                        <span className="flex min-w-0 flex-1 flex-col">
                          <span className="truncate text-zinc-900 dark:text-zinc-100">
                            {entry.name}
                          </span>
                          <span className="truncate text-xs text-zinc-500 dark:text-zinc-400">
                            {entry.email}
                          </span>
                        </span>
                        {checked ? (
                          <Check className="size-4 text-zinc-900 dark:text-zinc-100" />
                        ) : null}
                      </button>
                    );
                  })}
                  <Separator />
                  <button
                    className={ITEM_CLASS}
                    data-menu-item=""
                    data-row="add"
                    onClick={(event) => select(event, onAddAccount)}
                    role="menuitem"
                    tabIndex={-1}
                    type="button"
                  >
                    <span className="grid size-7 place-items-center rounded-full border border-zinc-300 border-dashed text-zinc-400 dark:border-zinc-700 dark:text-zinc-500">
                      <Plus className="size-3.5" />
                    </span>
                    Add account
                  </button>
                </motion.div>
              </div>
            </motion.div>
          </motion.div>
        </div>
      )}
    </div>
  );
}
```


---

# Scroll Index
> A section rail for long pages, with a tick per heading that you can hover, click or drag to scrub, built with React.

Source: https://kokonutui.com/docs/navigation/scroll-index

## Installation

```bash
npx shadcn@latest add @kokonutui/scroll-index
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Scroll Index
 * @version: 1.0.0
 * @date: 2026-10-15
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type ReactNode,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface ScrollIndexProps {
  /** The content to index. Defaults to a sample article. */
  children?: ReactNode;
  /** Which headings get a tick. */
  selector?: string;
  /**
   * `self`: the component scrolls its own box (default).
   * `window`: the page scrolls and the rail sticks beside the content.
   */
  scroller?: "self" | "window";
  className?: string;
}

interface Section {
  el: HTMLElement;
  text: string;
  level: number;
  /** Scroll position that brings the heading to the top. */
  at: number;
  /** Where its tick sits on the rail, 0 to 1. */
  pos: number;
}

// The rail is this tall at most, in px; ticks sit at the scroll position of
// their heading, so long sections leave long gaps.
const RAIL = 280;
// Headings land this far below the top edge when jumped to.
const OFFSET = 16;
// Ticks swell near the pointer like a dock: peak width and reach, in px.
const SWELL = 1.6;
const REACH = 26;
// A drag let go this close to a tick (after its momentum) settles on it.
const SNAP = 18;
// How long the flashed section name stays up after scrolling into it.
const FLASH = 900;

function easeInOut(t: number) {
  return t < 0.5 ? 8 * t ** 4 : 1 - (-2 * t + 2) ** 4 / 2;
}

export default function ScrollIndex({
  children,
  selector = "h2, h3",
  scroller = "self",
  className,
}: ScrollIndexProps) {
  const boxRef = useRef<HTMLDivElement>(null);
  const contentRef = useRef<HTMLDivElement>(null);
  const railRef = useRef<HTMLDivElement>(null);
  const headRef = useRef<HTMLSpanElement>(null);
  const labelRef = useRef<HTMLSpanElement>(null);
  const tickRefs = useRef<(HTMLButtonElement | null)[]>([]);
  const [sections, setSections] = useState<
    { text: string; level: number; pos: number }[]
  >([]);
  // The effect below reads and writes these without re-rendering.
  const api = useRef<{
    jump: (index: number) => void;
    show: (i: number) => void;
  }>({ jump: () => undefined, show: () => undefined });

  useEffect(() => {
    const box = boxRef.current;
    const content = contentRef.current;
    const rail = railRef.current;
    const head = headRef.current;
    const label = labelRef.current;
    if (!(box && content && rail && head && label)) {
      return;
    }
    const usesWindow = scroller === "window";
    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;

    let list: Section[] = [];
    let start = 0;
    let end = 1;
    let active = -1;
    let height = RAIL;
    let raf = 0;
    let tween = 0;
    let flashTimer = 0;
    let painted = false;
    let hover: number | null = null;
    let drag: {
      id: number;
      moved: boolean;
      y: number;
      t: number;
      v: number;
    } | null = null;
    const swell: number[] = [];

    const getScroll = () => (usesWindow ? window.scrollY : box.scrollTop);
    const setScroll = (value: number) => {
      if (usesWindow) {
        window.scrollTo(0, value);
      } else {
        box.scrollTop = value;
      }
    };

    const measure = () => {
      const scroll = getScroll();
      if (usesWindow) {
        const top = content.getBoundingClientRect().top + scroll;
        start = Math.max(top - OFFSET, 0);
        end = Math.max(
          top + content.offsetHeight - window.innerHeight,
          start + 1
        );
      } else {
        start = 0;
        end = Math.max(box.scrollHeight - box.clientHeight, 1);
      }
      const origin = usesWindow ? 0 : box.getBoundingClientRect().top - scroll;
      list = Array.from(content.querySelectorAll<HTMLElement>(selector)).map(
        (el) => {
          const at = Math.min(
            Math.max(
              el.getBoundingClientRect().top + scroll - origin - OFFSET,
              start
            ),
            end
          );
          return {
            el,
            text: el.textContent?.trim() ?? "",
            level: Number(el.tagName.slice(1)) || 2,
            at,
            pos: (at - start) / (end - start),
          };
        }
      );
      height = rail.clientHeight || RAIL;
      setSections(list.map(({ text, level, pos }) => ({ text, level, pos })));
    };

    const fraction = () =>
      Math.min(Math.max((getScroll() - start) / (end - start), 0), 1);

    const nearest = (y: number) => {
      let best = -1;
      let distance = Number.POSITIVE_INFINITY;
      list.forEach((s, i) => {
        const d = Math.abs(s.pos * height - y);
        if (d < distance) {
          distance = d;
          best = i;
        }
      });
      return { index: best, distance };
    };

    const placeLabel = (index: number, visible: boolean) => {
      const section = list[index];
      if (!section) {
        label.style.opacity = "0";
        return;
      }
      if (label.textContent !== section.text) {
        label.textContent = section.text;
      }
      label.style.transform = `translate3d(0, ${(section.pos * height).toFixed(1)}px, 0) translateY(-50%)`;
      label.style.opacity = visible ? "1" : "0";
    };

    /** Section the reader is in: the last heading at or above the top. */
    const current = () => {
      const scroll = getScroll() + 1;
      let index = -1;
      for (let i = 0; i < list.length; i++) {
        if (list[i].at <= scroll) {
          index = i;
        }
      }
      return index;
    };

    const paint = () => {
      raf = 0;
      head.style.transform = `translate3d(0, ${(fraction() * height).toFixed(1)}px, 0)`;
      const now = current();
      if (now !== active) {
        active = now;
        tickRefs.current.forEach((tick, i) => {
          if (tick) {
            tick.dataset.passed = i <= active ? "true" : "false";
          }
        });
        // Scrolling into a new section names it briefly.
        if (painted && hover === null && !drag && active >= 0) {
          placeLabel(active, true);
          window.clearTimeout(flashTimer);
          flashTimer = window.setTimeout(() => {
            if (hover === null && !drag) {
              label.style.opacity = "0";
            }
          }, FLASH);
        }
      }
      // Ticks ease toward their swell, so the magnification follows the
      // pointer smoothly instead of jumping.
      let moving = false;
      tickRefs.current.forEach((tick, i) => {
        if (!tick) {
          return;
        }
        const y = (list[i]?.pos ?? 0) * height;
        const target =
          hover === null || reduceMotion
            ? 1
            : 1 + SWELL * Math.exp(-((hover - y) ** 2) / (2 * REACH * REACH));
        const value = (swell[i] ?? 1) + (target - (swell[i] ?? 1)) * 0.35;
        swell[i] = Math.abs(value - target) < 0.005 ? target : value;
        moving ||= swell[i] !== target;
        tick.style.setProperty("--swell", swell[i].toFixed(3));
      });
      painted = true;
      if (moving) {
        schedule();
      }
    };

    function schedule() {
      if (!raf) {
        raf = requestAnimationFrame(paint);
      }
    }

    const stopTween = () => {
      cancelAnimationFrame(tween);
      tween = 0;
    };

    const scrollTo = (target: number) => {
      stopTween();
      const from = getScroll();
      const to = Math.min(Math.max(target, 0), usesWindow ? 1e9 : end);
      if (reduceMotion || Math.abs(to - from) < 2) {
        setScroll(to);
        return;
      }
      const duration = Math.min(
        Math.max(260 + Math.abs(to - from) * 0.12, 300),
        650
      );
      const begin = performance.now();
      const step = (now: number) => {
        const t = Math.min((now - begin) / duration, 1);
        setScroll(from + (to - from) * easeInOut(t));
        tween = t < 1 ? requestAnimationFrame(step) : 0;
      };
      tween = requestAnimationFrame(step);
    };

    api.current = {
      jump: (index) => {
        const section = list[index];
        if (section) {
          scrollTo(section.at);
        }
      },
      show: (index) => {
        hover = (list[index]?.pos ?? 0) * height;
        placeLabel(index, true);
        schedule();
      },
    };

    const railY = (event: PointerEvent) =>
      Math.min(
        Math.max(event.clientY - rail.getBoundingClientRect().top, 0),
        height
      );

    const scrub = (y: number) =>
      setScroll(start + (y / height) * (end - start));

    const onDown = (event: PointerEvent) => {
      if (drag || event.button !== 0) {
        return;
      }
      event.preventDefault();
      rail.setPointerCapture(event.pointerId);
      stopTween();
      const y = railY(event);
      drag = { id: event.pointerId, moved: false, y, t: event.timeStamp, v: 0 };
      hover = y;
      rail.dataset.dragging = "";
      placeLabel(nearest(y).index, true);
      schedule();
    };

    const onMove = (event: PointerEvent) => {
      const y = railY(event);
      if (drag && event.pointerId === drag.id) {
        const dt = Math.max(event.timeStamp - drag.t, 1);
        drag.v = drag.v * 0.4 + ((y - drag.y) / dt) * 0.6;
        drag.moved ||= Math.abs(y - drag.y) > 3;
        drag.y = y;
        drag.t = event.timeStamp;
        if (drag.moved) {
          // Dragging the rail scrubs the page under it.
          scrub(y);
        }
      } else if (event.pointerType !== "mouse") {
        return;
      }
      hover = y;
      placeLabel(nearest(y).index, true);
      schedule();
    };

    const onUp = (event: PointerEvent) => {
      if (!drag || event.pointerId !== drag.id) {
        return;
      }
      const { moved, y, v } = drag;
      drag = null;
      delete rail.dataset.dragging;
      if (event.pointerType !== "mouse") {
        hover = null;
        placeLabel(-1, false);
      }
      // Where the flick was heading, then the tick nearest that.
      const projected = moved ? y + v * 120 : y;
      const hit = nearest(projected);
      if (hit.index >= 0 && (!moved || hit.distance < SNAP)) {
        api.current.jump(hit.index);
      }
      schedule();
    };

    const onLeave = () => {
      if (drag) {
        return;
      }
      hover = null;
      placeLabel(-1, false);
      schedule();
    };

    const scrollTarget: HTMLElement | Window = usesWindow ? window : box;
    const onScroll = () => schedule();
    // Any scroll input of the reader's own cancels a jump in progress.
    const onInput = () => stopTween();

    measure();
    paint();
    const resize = new ResizeObserver(() => {
      measure();
      schedule();
    });
    resize.observe(content);
    resize.observe(box);
    scrollTarget.addEventListener("scroll", onScroll, { passive: true });
    scrollTarget.addEventListener("wheel", onInput, { passive: true });
    scrollTarget.addEventListener("touchstart", onInput, { passive: true });
    rail.addEventListener("pointerdown", onDown);
    rail.addEventListener("pointermove", onMove);
    rail.addEventListener("pointerup", onUp);
    rail.addEventListener("pointercancel", onUp);
    rail.addEventListener("pointerleave", onLeave);

    return () => {
      cancelAnimationFrame(raf);
      stopTween();
      window.clearTimeout(flashTimer);
      resize.disconnect();
      scrollTarget.removeEventListener("scroll", onScroll);
      scrollTarget.removeEventListener("wheel", onInput);
      scrollTarget.removeEventListener("touchstart", onInput);
      rail.removeEventListener("pointerdown", onDown);
      rail.removeEventListener("pointermove", onMove);
      rail.removeEventListener("pointerup", onUp);
      rail.removeEventListener("pointercancel", onUp);
      rail.removeEventListener("pointerleave", onLeave);
    };
  }, [selector, scroller]);

  const onTickKey = (index: number, event: KeyboardEvent) => {
    if (event.key !== "ArrowDown" && event.key !== "ArrowUp") {
      return;
    }
    event.preventDefault();
    const next = Math.min(
      Math.max(index + (event.key === "ArrowDown" ? 1 : -1), 0),
      sections.length - 1
    );
    tickRefs.current[next]?.focus();
  };

  const self = scroller === "self";

  return (
    <div
      className={cn(
        "relative w-full",
        self &&
          "h-[520px] overflow-hidden rounded-2xl border border-zinc-200 bg-white dark:border-zinc-800 dark:bg-zinc-950",
        !self && "grid grid-cols-[minmax(0,1fr)_3rem] gap-6",
        className
      )}
    >
      <div
        className={cn(self && "h-full overflow-y-auto overscroll-contain")}
        ref={boxRef}
      >
        <div
          className={cn(self && "py-8 pr-16 pl-6 sm:pl-10")}
          ref={contentRef}
        >
          {children ?? <SampleArticle />}
        </div>
      </div>

      <nav
        aria-label="Sections"
        className={cn(
          "z-10 flex w-12 justify-end",
          self
            ? "absolute top-1/2 right-3 -translate-y-1/2"
            : "sticky top-[calc(50vh-140px)] h-fit self-start"
        )}
      >
        <div
          className="relative w-full cursor-pointer touch-none select-none data-[dragging]:cursor-grabbing"
          ref={railRef}
          style={{ height: RAIL }}
        >
          {sections.map((section, index) => (
            <button
              aria-label={section.text}
              className={cn(
                "absolute right-0 h-4 -translate-y-1/2 rounded-sm outline-none focus-visible:ring-2 focus-visible:ring-zinc-400",
                section.level <= 2 ? "w-3.5" : "w-2"
              )}
              data-passed="false"
              key={`${index}-${section.text}`}
              onBlur={() => labelRef.current?.style.setProperty("opacity", "0")}
              onClick={(event) => {
                // Pointer clicks are handled by the rail; this is the keyboard.
                if (event.detail === 0) {
                  api.current.jump(index);
                }
              }}
              onFocus={() => api.current.show(index)}
              onKeyDown={(event) => onTickKey(index, event)}
              ref={(el) => {
                tickRefs.current[index] = el;
              }}
              style={{ top: `${(section.pos * 100).toFixed(3)}%` }}
              tabIndex={0}
              type="button"
            >
              <span className="absolute top-1/2 right-0 h-[1.5px] w-full origin-right -translate-y-1/2 scale-x-[var(--swell,1)] rounded-full bg-zinc-300 in-data-[passed=true]:bg-zinc-900 transition-colors duration-200 ease-out dark:bg-zinc-700 dark:in-data-[passed=true]:bg-zinc-100" />
            </button>
          ))}
          {/* Where the reader is, between ticks too. */}
          <span
            aria-hidden="true"
            className="pointer-events-none absolute top-0 right-0 h-[2px] w-6 -translate-y-1/2 rounded-full bg-zinc-900 will-change-transform dark:bg-zinc-100"
            ref={headRef}
          />
          <span
            aria-hidden="true"
            className="pointer-events-none absolute top-0 right-9 whitespace-nowrap rounded-md border border-zinc-200 bg-white px-2 py-1 font-medium text-xs text-zinc-700 opacity-0 shadow-sm transition-[opacity,transform] duration-150 ease-out dark:border-zinc-800 dark:bg-zinc-900 dark:text-zinc-200"
            ref={labelRef}
          />
        </div>
      </nav>
    </div>
  );
}

function SampleArticle() {
  const p = "mt-3 text-[15px] text-zinc-600 leading-relaxed dark:text-zinc-400";
  const h2 =
    "mt-12 font-semibold text-xl text-zinc-900 tracking-tight first:mt-0 dark:text-zinc-100";
  const h3 = "mt-8 font-medium text-base text-zinc-900 dark:text-zinc-100";
  return (
    <article className="mx-auto max-w-xl">
      <p className="font-medium text-xs text-zinc-400 dark:text-zinc-500">
        Field notes · 8 min read
      </p>
      <h2 className={cn(h2, "mt-2 text-2xl")}>Building a component library</h2>
      <p className={p}>
        A component library is a promise: that the next screen will be faster to
        build than the last, and that it will feel like the same product. These
        notes cover what we learned keeping that promise for two years.
      </p>
      <p className={p}>
        Most of it is about saying no. Every prop is a decision someone else has
        to make, and every variant is a screen that drifts.
      </p>
      <h2 className={h2}>Principles</h2>
      <p className={p}>
        Three rules settled most arguments before they started. Write them down
        early, and point to them often.
      </p>
      <h3 className={h3}>Restraint</h3>
      <p className={p}>
        Ship the smallest component that solves the problem in front of you. A
        button with four sizes is easier to live with than one with nine, and
        nobody has ever asked for the fifth.
      </p>
      <h3 className={h3}>Motion with a purpose</h3>
      <p className={p}>
        Animation explains where something came from and where it went. Anything
        else is decoration, and decoration ages quickly. Keep interface motion
        under 300 ms and let people interrupt it.
      </p>
      <h2 className={h2}>Tokens</h2>
      <p className={p}>
        Tokens are the vocabulary. Color, type, spacing and radius live in one
        place, so a rebrand is a pull request rather than a quarter.
      </p>
      <h3 className={h3}>Color</h3>
      <p className={p}>
        Name colors by job, not by hue. A surface, a border and a muted label
        survive a palette change; a gray-150 never does.
      </p>
      <h3 className={h3}>Type</h3>
      <p className={p}>
        Two families and five sizes cover nearly everything. Line height is part
        of the size, never a separate choice.
      </p>
      <h2 className={h2}>Components</h2>
      <p className={p}>
        Build from the inside out: primitives first, then the pieces that
        compose them. A dialog is a portal, a focus trap and a surface before it
        is ever a confirmation box.
      </p>
      <p className={p}>
        Keep the API close to the platform. If it behaves like a button, it is a
        button element, with every attribute a button takes.
      </p>
      <h2 className={h2}>Accessibility</h2>
      <p className={p}>
        Keyboard first. If a component can't be used without a mouse, it is not
        finished. Test with a screen reader before review, not after launch, and
        treat reduced motion as a real setting.
      </p>
      <h2 className={h2}>Shipping</h2>
      <p className={p}>
        Release small and often. A changelog people actually read is worth more
        than a migration guide nobody finds.
      </p>
      <p className={p}>
        Every release gets a short note: what changed, why, and what to do about
        it, in that order.
      </p>
      <h2 className={h2}>What's next</h2>
      <p className={p}>
        Theming per product, a token pipeline that feeds design and code from
        the same file, and fewer components, not more.
      </p>
      <p className={cn(p, "pb-40")}>
        Thanks for reading. Drag the rail on the right to move through these
        notes, or hover it to see where each section starts.
      </p>
    </article>
  );
}
```


---

# Smooth Drawer
> Bottom drawer with spring-based slide-in and staggered content reveal, built on Vaul with React, Motion, and Tailwind CSS.

Source: https://kokonutui.com/docs/navigation/smooth-drawer

## Installation

```bash
npx shadcn@latest add @kokonutui/smooth-drawer
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Smooth Drawer
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { Fingerprint } from "lucide-react";
import { motion, useReducedMotion, type Variants } from "motion/react";
import Image from "next/image";
import Link from "next/link";
import type * as React from "react";
import { Button } from "@/components/ui/button";
import {
  Drawer,
  DrawerClose,
  DrawerContent,
  DrawerDescription,
  DrawerFooter,
  DrawerHeader,
  DrawerTitle,
  DrawerTrigger,
} from "@/components/ui/drawer";

interface PriceTagProps {
  price: number;
  discountedPrice: number;
}

function PriceTag({ price, discountedPrice }: PriceTagProps) {
  return (
    <div className="mx-auto flex max-w-fit items-center justify-around gap-4">
      <div className="flex items-baseline gap-2">
        <span className="font-bold text-4xl text-zinc-900 dark:text-white">
          ${discountedPrice}
        </span>
        <span className="text-lg text-zinc-400 line-through dark:text-zinc-500">
          ${price}
        </span>
      </div>
      <div className="flex flex-col items-center gap-0.5">
        <span className="font-medium text-sm text-zinc-900 dark:text-zinc-100">
          Lifetime access
        </span>
        <span className="text-xs text-zinc-700 dark:text-zinc-300">
          One-time payment
        </span>
      </div>
    </div>
  );
}

interface SmoothDrawerProps extends React.HTMLAttributes<HTMLDivElement> {
  title?: string;
  description?: string;
  primaryButtonText?: string;
  secondaryButtonText?: string;
  onPrimaryAction?: () => void;
  /** Link for the primary button. Defaults to the demo's pricing page. */
  primaryHref?: string;
  onSecondaryAction?: () => void;
  price?: number;
  discountedPrice?: number;
}

const EASE_OUT = [0.23, 1, 0.32, 1] as const;

// vaul already slides the sheet in, so the content only staggers a short
// fade-up instead of sliding in a second time.
const drawerVariants = {
  hidden: {},
  visible: {
    transition: { staggerChildren: 0.04 },
  },
} satisfies Variants;

const itemVariants = {
  hidden: { y: 8, opacity: 0 },
  visible: {
    y: 0,
    opacity: 1,
    transition: { duration: 0.2, ease: EASE_OUT },
  },
} satisfies Variants;

const reducedItemVariants = {
  hidden: { opacity: 0 },
  visible: {
    opacity: 1,
    transition: { duration: 0.2, ease: EASE_OUT },
  },
} satisfies Variants;

// Hovering the CTA sweeps the shine across once and wiggles the icon once;
// leaving snaps the shine back out of view instead of sweeping it back.
const shineVariants = {
  rest: { x: "-100%", transition: { duration: 0 } },
  hover: { x: "100%", transition: { duration: 1.5, ease: "easeInOut" } },
} satisfies Variants;

const fingerprintVariants = {
  rest: { rotate: 0, y: 0, transition: { duration: 0.2, ease: EASE_OUT } },
  hover: {
    rotate: [0, 15, -15, 0],
    y: [0, -2, 2, 0],
    transition: { duration: 0.6, ease: "easeInOut" },
  },
} satisfies Variants;

export default function SmoothDrawer({
  title = "KokonutUI - Pro",
  description = "100+ collection of UI Components and templates built for React, Next.js, and Tailwind CSS. Spend no time on design and focus on shipping.",
  primaryButtonText = "Buy Now",
  secondaryButtonText = "Maybe Later",
  onPrimaryAction,
  primaryHref = "https://kokonutui.pro/#pricing",
  onSecondaryAction,
  price = 169,
  discountedPrice = 99,
}: SmoothDrawerProps) {
  const shouldReduceMotion = useReducedMotion();
  const item = shouldReduceMotion ? reducedItemVariants : itemVariants;

  return (
    <Drawer>
      <DrawerTrigger asChild>
        <Button variant="outline">Open Drawer</Button>
      </DrawerTrigger>
      <DrawerContent className="mx-auto max-w-fit rounded-2xl p-6 shadow-xl data-[vaul-drawer-direction=bottom]:rounded-t-2xl">
        <motion.div
          animate="visible"
          className="mx-auto w-full max-w-[340px] space-y-6"
          initial="hidden"
          variants={drawerVariants}
        >
          <motion.div variants={item}>
            <DrawerHeader className="space-y-2.5 px-0">
              <DrawerTitle className="flex items-center gap-2.5 font-semibold text-2xl tracking-tighter">
                {/* Spans: a heading only allows phrasing content. */}
                <motion.span className="block" variants={item}>
                  <span className="block rounded-xl bg-gradient-to-br from-zinc-100 to-zinc-200 p-1.5 shadow-inner dark:from-zinc-800 dark:to-zinc-900">
                    <Image
                      alt=""
                      height={32}
                      src="https://kokonutui.com/logo.svg"
                      unoptimized
                      width={32}
                    />
                  </span>
                </motion.span>
                <motion.span variants={item}>{title}</motion.span>
              </DrawerTitle>
              <motion.div variants={item}>
                <DrawerDescription className="text-sm text-zinc-600 leading-relaxed dark:text-zinc-400">
                  {description}
                </DrawerDescription>
              </motion.div>
            </DrawerHeader>
          </motion.div>

          <motion.div variants={item}>
            <PriceTag discountedPrice={discountedPrice} price={price} />
          </motion.div>

          <motion.div variants={item}>
            <DrawerFooter className="flex flex-col gap-3 px-0">
              <motion.div
                animate="rest"
                className="w-full"
                initial="rest"
                whileHover={shouldReduceMotion ? undefined : "hover"}
              >
                <Link
                  className="group relative inline-flex h-11 w-full items-center justify-center overflow-hidden rounded-xl bg-gradient-to-r from-rose-500 to-pink-500 font-semibold text-sm text-white shadow-lg shadow-rose-500/20 transition-[--tw-gradient-from,--tw-gradient-to,box-shadow,scale] duration-200 ease-out hover:from-rose-600 hover:to-pink-600 hover:shadow-rose-500/30 hover:shadow-xl motion-safe:active:scale-[0.97] dark:from-rose-600 dark:to-pink-600 dark:hover:from-rose-500 dark:hover:to-pink-500"
                  href={primaryHref}
                  onClick={onPrimaryAction}
                  target="_blank"
                >
                  <motion.span
                    className="absolute inset-0 bg-gradient-to-r from-transparent via-white/20 to-transparent"
                    variants={shineVariants}
                  />
                  <div className="relative flex items-center gap-2">
                    {primaryButtonText}
                    <motion.div variants={fingerprintVariants}>
                      <Fingerprint className="h-4 w-4" />
                    </motion.div>
                  </div>
                </Link>
              </motion.div>
              <DrawerClose asChild>
                <Button
                  className="h-11 w-full rounded-xl border-zinc-200 font-semibold text-sm transition-colors hover:bg-zinc-100 dark:border-zinc-800 dark:hover:bg-zinc-800/80"
                  onClick={onSecondaryAction}
                  variant="outline"
                >
                  {secondaryButtonText}
                </Button>
              </DrawerClose>
            </DrawerFooter>
          </motion.div>
        </motion.div>
      </DrawerContent>
    </Drawer>
  );
}
```


---

# Swipe Tabs
> Tabs with a swipeable panel, a drag-tracked indicator and spring physics.

Source: https://kokonutui.com/docs/navigation/smooth-tab

## Installation

```bash
npx shadcn@latest add @kokonutui/smooth-tab
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Swipe Tabs
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import type { LucideIcon } from "lucide-react";
import {
  type AnimationPlaybackControls,
  animate,
  useMotionValue,
} from "motion/react";
import {
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface SwipeTabItem {
  id: string;
  title: string;
  /** Shown before the title in the tab. */
  icon?: LucideIcon;
  /** The panel shown for this tab. */
  content?: ReactNode;
}

export interface SmoothTabProps {
  items?: SwipeTabItem[];
  defaultTabId?: string;
  /** The selected tab id, for a controlled tab. Pair it with `onChange`. */
  value?: string;
  onChange?: (tabId: string) => void;
  className?: string;
  /** Background classes for the indicator: the one accent. */
  activeColor?: string;
  /** Text color classes for the label sitting on the indicator. */
  activeTextColor?: string;
  /** Accessible name for the tab list. */
  label?: string;
}

// Past the first or last tab the panel moves this fraction of the drag.
const RUBBER_BAND = 0.35;
// A release this fast (px per ms) changes tab however short the drag was.
const SWIPE_VELOCITY = 0.11;
// Movement before deciding between a horizontal swipe and a vertical scroll.
const AXIS_LOCK = 6;
// Release velocity is measured over the last stretch of the drag only.
const VELOCITY_WINDOW = 100;
// A panel one full width away sits at this opacity, so the neighbour reads
// as "next" while it slides in.
const NEIGHBOUR_OPACITY = 0.35;
// Just under critical damping: a firm settle, a hint of overshoot only after
// a fast flick.
const SPRING = { type: "spring", stiffness: 420, damping: 38 } as const;
const EASE_OUT = [0.23, 1, 0.32, 1] as const;

interface TabRect {
  left: number;
  width: number;
  top: number;
  height: number;
}

interface Drag {
  pointerId: number;
  startX: number;
  startY: number;
  startProgress: number;
  axis: "x" | "y" | null;
  width: number;
  samples: { x: number; t: number }[];
}

const lerp = (a: number, b: number, t: number) => a + (b - a) * t;
const clamp = (v: number, min: number, max: number) =>
  Math.min(Math.max(v, min), max);

/** The indicator rectangle at a fractional tab position. */
function indicatorRect(rects: TabRect[], progress: number): TabRect | null {
  const last = rects.length - 1;
  if (last < 0) {
    return null;
  }
  const p = clamp(progress, 0, last);
  const i = Math.min(Math.floor(p), Math.max(last - 1, 0));
  const a = rects[i];
  const b = rects[Math.min(i + 1, last)];
  const t = p - i;
  let left = lerp(a.left, b.left, t);
  let width = lerp(a.width, b.width, t);
  // Rubber-banding past an end: the pill presses against the wall and gives
  // on the far side instead of sliding out of the track.
  const over = progress < 0 ? -progress : progress - last;
  if (over > 0) {
    const squash = width * Math.min(over, 0.5) * 0.4;
    width -= squash;
    if (progress > last) {
      left += squash;
    }
  }
  return { left, width, top: a.top, height: a.height };
}

/** Rubber-bands a raw position that runs past the first or last tab. */
function rubberBand(raw: number, last: number): number {
  if (raw < 0) {
    return raw * RUBBER_BAND;
  }
  if (raw > last) {
    return last + (raw - last) * RUBBER_BAND;
  }
  return raw;
}

function Stat({ label, value }: { label: string; value: string }) {
  return (
    <div className="rounded-lg bg-zinc-100 px-3 py-2.5 dark:bg-zinc-900">
      <p className="text-[11px] text-zinc-500 dark:text-zinc-400">{label}</p>
      <p className="mt-0.5 font-medium text-sm text-zinc-900 tabular-nums dark:text-zinc-100">
        {value}
      </p>
    </div>
  );
}

const BARS = [38, 52, 44, 61, 57, 72, 66, 80, 74, 88, 69, 92];

const ACTIVITY = [
  ["Deploy #418 promoted to production", "2m"],
  ["Preview built for fix/auth-redirect", "14m"],
  ["Environment variable rotated", "1h"],
  ["Domain app.example.com verified", "3h"],
];

const MEMBERS = [
  ["AL", "Avery Lane", "Owner"],
  ["JR", "Jordan Reyes", "Admin"],
  ["SK", "Sam Kato", "Developer"],
  ["RM", "Riley Moss", "Viewer"],
];

const DEFAULT_TABS: SwipeTabItem[] = [
  {
    id: "overview",
    title: "Overview",
    content: (
      <div className="flex h-full flex-col gap-4">
        <div className="grid grid-cols-3 gap-2">
          <Stat label="Requests" value="24.1k" />
          <Stat label="Errors" value="0.12%" />
          <Stat label="p95" value="182 ms" />
        </div>
        <div aria-hidden="true" className="flex h-24 items-end gap-1.5">
          {BARS.map((h, i) => (
            <span
              className={cn(
                "flex-1 rounded-sm",
                i === BARS.length - 1
                  ? "bg-zinc-900 dark:bg-zinc-100"
                  : "bg-zinc-200 dark:bg-zinc-800"
              )}
              key={`bar-${i.toString()}`}
              style={{ height: `${h}%` }}
            />
          ))}
        </div>
      </div>
    ),
  },
  {
    id: "activity",
    title: "Activity",
    content: (
      <ol className="flex flex-col divide-y divide-zinc-200 dark:divide-zinc-800">
        {ACTIVITY.map(([text, time]) => (
          <li
            className="flex items-center justify-between gap-3 py-2.5 first:pt-0"
            key={text}
          >
            <span className="truncate text-sm text-zinc-700 dark:text-zinc-300">
              {text}
            </span>
            <span className="shrink-0 text-xs text-zinc-400 tabular-nums">
              {time}
            </span>
          </li>
        ))}
      </ol>
    ),
  },
  {
    id: "members",
    title: "Members",
    content: (
      <ul className="flex flex-col gap-3">
        {MEMBERS.map(([initials, name, role]) => (
          <li className="flex items-center gap-3" key={name}>
            <span className="flex size-8 shrink-0 items-center justify-center rounded-full bg-zinc-100 font-medium text-[11px] text-zinc-600 dark:bg-zinc-900 dark:text-zinc-300">
              {initials}
            </span>
            <span className="flex-1 truncate text-sm text-zinc-800 dark:text-zinc-200">
              {name}
            </span>
            <span className="text-xs text-zinc-500 dark:text-zinc-400">
              {role}
            </span>
          </li>
        ))}
      </ul>
    ),
  },
  {
    id: "billing",
    title: "Billing",
    content: (
      <div className="flex h-full flex-col gap-5">
        <div className="flex items-baseline justify-between">
          <p className="font-medium text-sm text-zinc-900 dark:text-zinc-100">
            Pro plan
          </p>
          <p className="text-sm text-zinc-500 tabular-nums dark:text-zinc-400">
            $20 / month
          </p>
        </div>
        <div>
          <div className="mb-1.5 flex justify-between text-xs text-zinc-500 dark:text-zinc-400">
            <span>Bandwidth</span>
            <span className="tabular-nums">64 / 100 GB</span>
          </div>
          <div className="h-1.5 overflow-hidden rounded-full bg-zinc-100 dark:bg-zinc-900">
            <div className="h-full w-[64%] rounded-full bg-zinc-900 dark:bg-zinc-100" />
          </div>
        </div>
        <p className="mt-auto text-xs text-zinc-500 dark:text-zinc-400">
          Next invoice on Nov 1 · Card ending 4242
        </p>
      </div>
    ),
  },
];

export default function SmoothTab({
  items = DEFAULT_TABS,
  defaultTabId,
  value,
  onChange,
  className,
  activeColor = "bg-zinc-900 dark:bg-zinc-100",
  activeTextColor = "text-white dark:text-zinc-900",
  label = "Sections",
}: SmoothTabProps) {
  const count = items.length;
  const indexOf = (id: string | undefined) =>
    Math.max(
      items.findIndex((item) => item.id === id),
      0
    );

  const [uncontrolled, setUncontrolled] = useState(() => indexOf(defaultTabId));
  const selected =
    value === undefined
      ? clamp(uncontrolled, 0, Math.max(count - 1, 0))
      : indexOf(value);
  // Captured once, so React never rewrites the imperatively painted styles.
  const [initial] = useState(selected);

  // Fractional tab position: 0 … count - 1, beyond while rubber-banding.
  // It drives the panel track, the indicator and the label clip directly,
  // so a drag never re-renders React.
  const progress = useMotionValue(selected);

  const baseId = useId();
  const tablistRef = useRef<HTMLDivElement>(null);
  const overlayRef = useRef<HTMLDivElement>(null);
  const trackRef = useRef<HTMLDivElement>(null);
  const tabRefs = useRef<(HTMLButtonElement | null)[]>([]);
  const panelRefs = useRef<(HTMLDivElement | null)[]>([]);
  const rects = useRef<TabRect[]>([]);
  const size = useRef({ width: 0, height: 0 });
  const anim = useRef<AnimationPlaybackControls | null>(null);
  const target = useRef(selected);
  const drag = useRef<Drag | null>(null);
  const suppressClick = useRef(false);
  const reducedMotion = useRef(false);
  const latest = useRef({ count, items, selected, onChange });
  latest.current = { count, items, selected, onChange };

  const paint = useCallback(
    (p: number) => {
      const track = trackRef.current;
      if (track) {
        track.style.transform = `translate3d(${(-p * 100) / count}%, 0, 0)`;
      }
      panelRefs.current.forEach((panel, i) => {
        if (panel) {
          const d = Math.min(Math.abs(p - i), 1);
          panel.style.opacity = String(1 - d * (1 - NEIGHBOUR_OPACITY));
        }
      });
      const overlay = overlayRef.current;
      const r = indicatorRect(rects.current, p);
      if (overlay && r) {
        const right = size.current.width - r.left - r.width;
        const bottom = size.current.height - r.top - r.height;
        overlay.style.clipPath = `inset(${r.top}px ${right}px ${bottom}px ${r.left}px round ${r.height / 2}px)`;
      }
    },
    [count]
  );

  // Measure the tabs before paint, and again on resize and font load.
  useLayoutEffect(() => {
    const tablist = tablistRef.current;
    if (!tablist) {
      return;
    }
    let alive = true;
    const measure = () => {
      if (!alive) {
        return;
      }
      // Sub-pixel rects, so the clip lines up with the labels exactly.
      // Divided by the list's scale in case an ancestor is transformed.
      const box = tablist.getBoundingClientRect();
      const ratio = box.width / (tablist.offsetWidth || 1);
      // offsetWidth is rounded: only a real transform counts as a scale.
      const scale = Math.abs(ratio - 1) < 0.01 ? 1 : ratio;
      size.current = { width: box.width / scale, height: box.height / scale };
      rects.current = tabRefs.current.slice(0, count).map((tab) => {
        const r = tab?.getBoundingClientRect();
        return r
          ? {
              left: (r.left - box.left) / scale,
              width: r.width / scale,
              top: (r.top - box.top) / scale,
              height: r.height / scale,
            }
          : { left: 0, width: 0, top: 0, height: 0 };
      });
      paint(progress.get());
    };
    measure();
    const observer = new ResizeObserver(measure);
    observer.observe(tablist);
    document.fonts.ready.then(measure).catch(() => undefined);
    return () => {
      alive = false;
      observer.disconnect();
    };
  }, [count, paint, progress]);

  useEffect(() => {
    const unsubscribe = progress.on("change", paint);
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    const sync = () => {
      reducedMotion.current = query.matches;
    };
    sync();
    query.addEventListener("change", sync);
    return () => {
      unsubscribe();
      query.removeEventListener("change", sync);
      anim.current?.stop();
    };
  }, [paint, progress]);

  /** Moves the position to a tab. `velocity` is in tabs per second. */
  const settle = useCallback(
    (index: number, opts: { instant?: boolean; velocity?: number } = {}) => {
      target.current = index;
      anim.current?.stop();
      anim.current = null;
      if (opts.instant) {
        progress.jump(index);
        return;
      }
      anim.current = reducedMotion.current
        ? animate(progress, index, { duration: 0.15, ease: EASE_OUT })
        : animate(progress, index, { ...SPRING, velocity: opts.velocity ?? 0 });
    },
    [progress]
  );

  const select = useCallback(
    (index: number, opts?: { instant?: boolean; velocity?: number }) => {
      const { count: n, items: list, selected: current } = latest.current;
      const next = clamp(index, 0, n - 1);
      settle(next, opts);
      if (next !== current) {
        setUncontrolled(next);
        latest.current.onChange?.(list[next].id);
      }
    },
    [settle]
  );

  // A controlled `value` changed from outside: follow it.
  useEffect(() => {
    if (selected !== target.current && !drag.current) {
      settle(selected);
    }
  }, [selected, settle]);

  const handleKeyDown = (e: KeyboardEvent<HTMLButtonElement>, i: number) => {
    const keys: Record<string, number> = {
      ArrowRight: (i + 1) % count,
      ArrowLeft: (i - 1 + count) % count,
      Home: 0,
      End: count - 1,
    };
    const next = keys[e.key];
    if (next === undefined) {
      return;
    }
    e.preventDefault();
    tabRefs.current[next]?.focus();
    // A held key repeats faster than any spring settles: jump instead.
    select(next, { instant: e.repeat });
  };

  const onPointerDown = (e: PointerEvent<HTMLDivElement>) => {
    if (count < 2 || (e.pointerType === "mouse" && e.button !== 0)) {
      return;
    }
    drag.current = {
      pointerId: e.pointerId,
      startX: e.clientX,
      startY: e.clientY,
      startProgress: progress.get(),
      axis: null,
      width: e.currentTarget.clientWidth || 1,
      samples: [{ x: e.clientX, t: e.timeStamp }],
    };
  };

  const lockAxis = (current: Drag, e: PointerEvent<HTMLDivElement>) => {
    const dx = e.clientX - current.startX;
    const dy = e.clientY - current.startY;
    if (Math.max(Math.abs(dx), Math.abs(dy)) < AXIS_LOCK) {
      return;
    }
    // Vertical wins ties: the page scroll is what most people are after.
    current.axis = Math.abs(dx) > Math.abs(dy) ? "x" : "y";
    if (current.axis === "x") {
      // Catch the panel mid-flight, and keep the swipe alive when the
      // pointer leaves the panel.
      anim.current?.stop();
      current.startProgress = progress.get();
      current.startX = e.clientX;
      current.samples = [{ x: e.clientX, t: e.timeStamp }];
      e.currentTarget.setPointerCapture(e.pointerId);
      e.currentTarget.dataset.dragging = "";
    }
  };

  const onPointerMove = (e: PointerEvent<HTMLDivElement>) => {
    const current = drag.current;
    if (!current || current.pointerId !== e.pointerId) {
      return;
    }
    if (current.axis === null) {
      lockAxis(current, e);
    }
    if (current.axis !== "x") {
      return;
    }
    current.samples.push({ x: e.clientX, t: e.timeStamp });
    while (
      current.samples.length > 2 &&
      e.timeStamp - current.samples[0].t > VELOCITY_WINDOW
    ) {
      current.samples.shift();
    }
    const raw =
      current.startProgress - (e.clientX - current.startX) / current.width;
    progress.set(rubberBand(raw, count - 1));
  };

  const endDrag = (e: PointerEvent<HTMLDivElement>, cancelled: boolean) => {
    const current = drag.current;
    if (!current || current.pointerId !== e.pointerId) {
      return;
    }
    drag.current = null;
    delete e.currentTarget.dataset.dragging;
    if (current.axis !== "x") {
      return;
    }
    // Swallow the click this release may send. A touch swipe sends none,
    // so the flag clears on the next tick instead of eating a later tap.
    if (!cancelled) {
      suppressClick.current = true;
      window.setTimeout(() => {
        suppressClick.current = false;
      }, 0);
    }
    const first = current.samples[0];
    // px per ms; negative is a swipe towards the next tab.
    const vx = (e.clientX - first.x) / Math.max(e.timeStamp - first.t, 1);
    const p = progress.get();
    let next = Math.round(p);
    if (!cancelled && Math.abs(vx) > SWIPE_VELOCITY) {
      next = vx < 0 ? Math.floor(p) + 1 : Math.ceil(p) - 1;
    }
    // The spring starts at the finger's speed, so the hand-off is seamless.
    select(next, { velocity: (-vx * 1000) / current.width });
  };

  const tabId = (i: number) => `${baseId}-tab-${i}`;
  const panelId = (i: number) => `${baseId}-panel-${i}`;

  return (
    <div className={cn("flex w-full max-w-md flex-col gap-3", className)}>
      <div className="flex justify-center">
        <div
          aria-label={label}
          className="relative inline-flex max-w-full rounded-full bg-zinc-100 p-1 dark:bg-zinc-900"
          ref={tablistRef}
          role="tablist"
        >
          {items.map((item, i) => {
            const Icon = item.icon;
            const isSelected = i === selected;
            return (
              <button
                aria-controls={panelId(i)}
                aria-selected={isSelected}
                className={cn(
                  "relative flex shrink-0 items-center gap-1.5 rounded-full px-3.5 py-1.5 font-medium text-sm",
                  "text-zinc-500 transition-colors duration-150 ease-out hover:text-zinc-900 dark:text-zinc-400 dark:hover:text-zinc-100",
                  "outline-none focus-visible:outline-2 focus-visible:outline-zinc-400 focus-visible:outline-offset-2"
                )}
                id={tabId(i)}
                key={item.id}
                onClick={() => select(i)}
                onKeyDown={(e) => handleKeyDown(e, i)}
                ref={(el) => {
                  tabRefs.current[i] = el;
                }}
                role="tab"
                tabIndex={isSelected ? 0 : -1}
                type="button"
              >
                {Icon && <Icon aria-hidden="true" className="size-4" />}
                <span className="whitespace-nowrap">{item.title}</span>
              </button>
            );
          })}
          {/* The same labels in the active color, clipped to the indicator,
              so each label is exactly right at every point of the slide with
              no color tween. */}
          <div
            aria-hidden="true"
            className={cn(
              "pointer-events-none absolute inset-0 flex p-1",
              activeColor
            )}
            ref={overlayRef}
            style={{ clipPath: "inset(0 100% 0 0)" }}
          >
            {items.map((item) => {
              const Icon = item.icon;
              return (
                <span
                  className={cn(
                    "flex shrink-0 items-center gap-1.5 px-3.5 py-1.5 font-medium text-sm",
                    activeTextColor
                  )}
                  key={item.id}
                >
                  {Icon && <Icon className="size-4" />}
                  <span className="whitespace-nowrap">{item.title}</span>
                </span>
              );
            })}
          </div>
        </div>
      </div>

      <div
        className="relative touch-pan-y select-none overflow-hidden rounded-2xl border border-zinc-200 bg-white data-dragging:cursor-grabbing dark:border-zinc-800 dark:bg-zinc-950"
        onClickCapture={(e) => {
          if (suppressClick.current) {
            suppressClick.current = false;
            e.preventDefault();
            e.stopPropagation();
          }
        }}
        onLostPointerCapture={(e) => endDrag(e, false)}
        onPointerCancel={(e) => endDrag(e, true)}
        onPointerDown={onPointerDown}
        onPointerMove={onPointerMove}
        onPointerUp={(e) => endDrag(e, false)}
      >
        <div
          className="flex will-change-transform"
          ref={trackRef}
          style={{
            width: `${count * 100}%`,
            transform: `translate3d(${(-initial * 100) / count}%, 0, 0)`,
          }}
        >
          {items.map((item, i) => (
            <div
              aria-labelledby={tabId(i)}
              className="min-h-[220px] p-5 outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-inset"
              id={panelId(i)}
              inert={i !== selected}
              key={item.id}
              ref={(el) => {
                panelRefs.current[i] = el;
              }}
              role="tabpanel"
              style={{
                width: `${100 / count}%`,
                opacity: i === initial ? 1 : NEIGHBOUR_OPACITY,
              }}
              tabIndex={i === selected ? 0 : -1}
            >
              {item.content}
            </div>
          ))}
        </div>
      </div>
    </div>
  );
}
```


---

# Tool Dock
> An editor tool dock with a sliding selection plate, shortcut tooltips and flyouts that you can throw to any edge.

Source: https://kokonutui.com/docs/navigation/toolbar

## Installation

```bash
npx shadcn@latest add @kokonutui/toolbar
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Tool Dock
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  Circle,
  GripHorizontal,
  GripVertical,
  Hand,
  type LucideIcon,
  MessageCircle,
  MousePointer2,
  PenTool,
  Slash,
  Square,
  Type,
} from "lucide-react";
import {
  AnimatePresence,
  type AnimationPlaybackControls,
  animate,
  motion,
  type Transition,
  useMotionValue,
  useReducedMotion,
  useTransform,
} from "motion/react";
import {
  type FocusEvent,
  type KeyboardEvent,
  type PointerEvent,
  type ReactNode,
  type RefObject,
  useCallback,
  useEffect,
  useId,
  useLayoutEffect,
  useMemo,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export type DockEdge = "top" | "right" | "bottom" | "left";

export interface DockTool {
  id: string;
  label: string;
  icon: LucideIcon;
  /** A single key that picks this tool, such as "V". */
  shortcut?: string;
  /** CSS cursor for the canvas while this tool is active. */
  cursor?: string;
  /** Sub-tools, shown in a flyout. The button shows the last one picked. */
  tools?: DockTool[];
}

export interface ToolbarProps {
  tools?: DockTool[];
  /** The active tool id, for a controlled dock. */
  value?: string;
  defaultValue?: string;
  onValueChange?: (toolId: string) => void;
  /** The edge of the canvas the dock starts on. */
  defaultEdge?: DockEdge;
  onEdgeChange?: (edge: DockEdge) => void;
  /**
   * When single-key shortcuts work. `scoped` (default) listens only while
   * focus is inside the canvas, or the pointer is over it and nothing else
   * has focus; `global` always listens. Never while typing.
   */
  shortcuts?: "scoped" | "global" | "off";
  /** Accessible name for the toolbar. */
  ariaLabel?: string;
  /** Classes for the canvas, the box the dock lives in. */
  className?: string;
  /** Classes for the dock itself. */
  dockClassName?: string;
  /** Canvas content drawn behind the dock. Defaults to a dot grid. */
  children?: ReactNode;
}

const DEFAULT_TOOLS: DockTool[] = [
  {
    id: "select",
    label: "Select",
    icon: MousePointer2,
    shortcut: "V",
    cursor: "default",
  },
  { id: "hand", label: "Hand", icon: Hand, shortcut: "H", cursor: "grab" },
  {
    id: "shapes",
    label: "Shapes",
    icon: Square,
    tools: [
      {
        id: "rectangle",
        label: "Rectangle",
        icon: Square,
        shortcut: "R",
        cursor: "crosshair",
      },
      {
        id: "ellipse",
        label: "Ellipse",
        icon: Circle,
        shortcut: "O",
        cursor: "crosshair",
      },
      {
        id: "line",
        label: "Line",
        icon: Slash,
        shortcut: "L",
        cursor: "crosshair",
      },
    ],
  },
  {
    id: "pen",
    label: "Pen",
    icon: PenTool,
    shortcut: "P",
    cursor: "crosshair",
  },
  { id: "text", label: "Text", icon: Type, shortcut: "T", cursor: "text" },
  {
    id: "comment",
    label: "Comment",
    icon: MessageCircle,
    shortcut: "C",
    cursor: "crosshair",
  },
];

/** Gap between the dock and the canvas edge, in px (Tailwind `3`). */
const EDGE_GAP = 12;
const TIP_DELAY = 400;
/** How long the tooltip group stays warm after a tooltip hides. */
const TIP_WARM = 300;
const TIP_OFFSET = 8;
const LONG_PRESS = 350;
/** iOS scroll deceleration; projects a flick about half a second ahead. */
const DECELERATION = 0.998;
const PROJECTION = DECELERATION / (1 - DECELERATION);
const VELOCITY_WINDOW = 100;

const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const INSTANT: Transition = { duration: 0 };
const PLATE_SPRING: Transition = { type: "spring", bounce: 0, duration: 0.25 };
const REFLOW_SPRING: Transition = { type: "spring", bounce: 0, duration: 0.4 };
/** Slightly underdamped: the dock carries its throw into the edge. */
const DOCK_SPRING = { type: "spring", stiffness: 380, damping: 32 } as const;
const DOCK_TWEEN = { duration: 0.2, ease: EASE_OUT } as const;

const NEXT_EDGE: Record<DockEdge, DockEdge> = {
  bottom: "left",
  left: "top",
  top: "right",
  right: "bottom",
};

/** Where the dock rests before it has measured the canvas (SSR). */
const RESTING: Record<DockEdge, string> = {
  bottom: "bottom-3 left-1/2 -translate-x-1/2",
  top: "top-3 left-1/2 -translate-x-1/2",
  left: "left-3 top-1/2 -translate-y-1/2",
  right: "right-3 top-1/2 -translate-y-1/2",
};

/** Popovers open away from the edge, growing out of the dock. */
const ORIGIN: Record<DockEdge, string> = {
  bottom: "50% 100%",
  top: "50% 0%",
  left: "0% 50%",
  right: "100% 50%",
};

const TIP_SHIFT: Record<DockEdge, string> = {
  bottom: "-translate-x-1/2 -translate-y-full",
  top: "-translate-x-1/2",
  left: "-translate-y-1/2",
  right: "-translate-x-full -translate-y-1/2",
};

const FLYOUT_SIDE: Record<DockEdge, string> = {
  bottom: "bottom-full left-1/2 mb-3 -translate-x-1/2",
  top: "top-full left-1/2 mt-3 -translate-x-1/2",
  left: "left-full top-1/2 ml-3 -translate-y-1/2",
  right: "right-full top-1/2 mr-3 -translate-y-1/2",
};

const FOCUS_RING =
  "outline-none focus-visible:ring-2 focus-visible:ring-zinc-400 dark:focus-visible:ring-zinc-500";

const isVertical = (edge: DockEdge) => edge === "left" || edge === "right";

const clamp = (v: number, min: number, max: number) =>
  min > max ? (min + max) / 2 : Math.min(max, Math.max(min, v));

function edgeTarget(
  edge: DockEdge,
  width: number,
  height: number,
  dockW: number,
  dockH: number
) {
  switch (edge) {
    case "top":
      return { x: width / 2, y: EDGE_GAP + dockH / 2 };
    case "left":
      return { x: EDGE_GAP + dockW / 2, y: height / 2 };
    case "right":
      return { x: width - EDGE_GAP - dockW / 2, y: height / 2 };
    default:
      return { x: width / 2, y: height - EDGE_GAP - dockH / 2 };
  }
}

function nearestEdge(
  x: number,
  y: number,
  width: number,
  height: number
): DockEdge {
  const distances: [DockEdge, number][] = [
    ["bottom", height - y],
    ["top", y],
    ["left", x],
    ["right", width - x],
  ];
  let best = distances[0];
  for (const entry of distances) {
    if (entry[1] < best[1]) {
      best = entry;
    }
  }
  return best[0];
}

const dockTransform = (x: number, y: number) =>
  `translate3d(${x}px, ${y}px, 0) translate(-50%, -50%)`;

/**
 * Where a dock that just changed orientation starts its spring: the side that
 * faces its new wall stays put, so the reflow grows away from the wall.
 */
function reflowStart(
  edge: DockEdge,
  x: number,
  y: number,
  from: { w: number; h: number },
  to: { w: number; h: number },
  width: number,
  height: number
) {
  let nx = x;
  let ny = y;
  if (edge === "left") {
    nx = x - from.w / 2 + to.w / 2;
  } else if (edge === "right") {
    nx = x + from.w / 2 - to.w / 2;
  } else if (edge === "top") {
    ny = y - from.h / 2 + to.h / 2;
  } else {
    ny = y + from.h / 2 - to.h / 2;
  }
  return {
    x: clamp(nx, to.w / 2, width - to.w / 2),
    y: clamp(ny, to.h / 2, height - to.h / 2),
  };
}

/** Tooltip anchor, relative to the dock box, on the side facing the canvas. */
function tipPosition(edge: DockEdge, button: DOMRect, dock: DOMRect) {
  const midX = Math.round(button.left + button.width / 2 - dock.left);
  const midY = Math.round(button.top + button.height / 2 - dock.top);
  switch (edge) {
    case "top":
      return { x: midX, y: Math.round(dock.height + TIP_OFFSET) };
    case "left":
      return { x: Math.round(dock.width + TIP_OFFSET), y: midY };
    case "right":
      return { x: -TIP_OFFSET, y: midY };
    default:
      return { x: midX, y: -TIP_OFFSET };
  }
}

const TEXT_ROLES = new Set(["textbox", "searchbox", "combobox", "spinbutton"]);

function isEditable(target: EventTarget | null | undefined) {
  if (!(target instanceof HTMLElement)) {
    return false;
  }
  return (
    target.isContentEditable ||
    target.tagName === "INPUT" ||
    target.tagName === "TEXTAREA" ||
    target.tagName === "SELECT" ||
    TEXT_ROLES.has(target.getAttribute("role") ?? "")
  );
}

/** True while the person is typing, including inside shadow roots. */
function isTyping(e: globalThis.KeyboardEvent) {
  return (
    e.isComposing ||
    isEditable(e.composedPath()[0]) ||
    isEditable(document.activeElement)
  );
}

function flatten(tools: DockTool[]) {
  const leaves: DockTool[] = [];
  const parentOf = new Map<string, string>();
  for (const tool of tools) {
    if (tool.tools?.length) {
      for (const sub of tool.tools) {
        leaves.push(sub);
        parentOf.set(sub.id, tool.id);
      }
    } else {
      leaves.push(tool);
    }
  }
  return { leaves, parentOf };
}

function Kbd({ children }: { children: ReactNode }) {
  return (
    <kbd className="min-w-4 rounded border border-current/20 px-1 text-center font-mono font-normal text-[10px] leading-4 opacity-70">
      {children}
    </kbd>
  );
}

interface TipState {
  label: string;
  shortcut?: string;
  x: number;
  y: number;
  animated: boolean;
}

interface Hint {
  show: (el: HTMLElement, label: string, shortcut?: string) => void;
  hide: () => void;
}

interface FlyoutProps {
  tool: DockTool;
  current: string;
  edge: DockEdge;
  focusOnOpen: boolean;
  reduced: boolean;
  onPick: (id: string) => void;
  onClose: (returnFocus: boolean) => void;
}

function menuStep(key: string, i: number, n: number) {
  switch (key) {
    case "ArrowDown":
      return (i + 1) % n;
    case "ArrowUp":
      return (i - 1 + n) % n;
    case "Home":
      return 0;
    case "End":
      return n - 1;
    default:
      return -1;
  }
}

function Flyout({
  tool,
  current,
  edge,
  focusOnOpen,
  reduced,
  onPick,
  onClose,
}: FlyoutProps) {
  const menuRef = useRef<HTMLDivElement>(null);
  const items = useCallback(
    () =>
      Array.from(
        menuRef.current?.querySelectorAll<HTMLElement>(
          '[role="menuitemradio"]'
        ) ?? []
      ),
    []
  );

  useEffect(() => {
    if (!focusOnOpen) {
      return;
    }
    const all = items();
    (
      all.find((el) => el.getAttribute("aria-checked") === "true") ?? all[0]
    )?.focus();
  }, [focusOnOpen, items]);

  const onKeyDown = (e: KeyboardEvent<HTMLDivElement>) => {
    if (e.key === "Escape") {
      e.preventDefault();
      e.stopPropagation();
      onClose(true);
      return;
    }
    if (e.key === "Tab") {
      onClose(false);
      return;
    }
    const all = items();
    const next = menuStep(
      e.key,
      all.indexOf(e.target as HTMLElement),
      all.length
    );
    if (next !== -1) {
      e.preventDefault();
      e.stopPropagation();
      all[next]?.focus();
    }
  };

  return (
    <div className={cn("absolute z-30", FLYOUT_SIDE[edge])}>
      <motion.div
        animate={{ opacity: 1, scale: 1 }}
        aria-label={tool.label}
        className="w-44 rounded-xl border border-zinc-200 bg-white p-1 shadow-lg dark:border-zinc-800 dark:bg-zinc-900"
        exit={{
          opacity: 0,
          scale: reduced ? 1 : 0.96,
          transition: { duration: 0.1, ease: EASE_OUT },
        }}
        initial={{ opacity: 0, scale: reduced ? 1 : 0.96 }}
        onKeyDown={onKeyDown}
        ref={menuRef}
        role="menu"
        style={{ transformOrigin: ORIGIN[edge] }}
        transition={{ duration: 0.15, ease: EASE_OUT }}
      >
        {tool.tools?.map((sub) => {
          const checked = sub.id === current;
          return (
            <button
              aria-checked={checked}
              aria-keyshortcuts={sub.shortcut}
              className={cn(
                "flex w-full items-center gap-2.5 rounded-lg px-2 py-1.5 text-left text-sm",
                "transition-colors duration-150",
                FOCUS_RING,
                checked
                  ? "bg-zinc-100 text-zinc-900 dark:bg-zinc-800 dark:text-zinc-50"
                  : "text-zinc-600 hover:bg-zinc-100 hover:text-zinc-900 dark:text-zinc-400 dark:hover:bg-zinc-800 dark:hover:text-zinc-50"
              )}
              key={sub.id}
              onClick={() => onPick(sub.id)}
              role="menuitemradio"
              tabIndex={-1}
              type="button"
            >
              <sub.icon aria-hidden className="size-4" strokeWidth={1.75} />
              <span className="flex-1">{sub.label}</span>
              {sub.shortcut ? <Kbd>{sub.shortcut}</Kbd> : null}
            </button>
          );
        })}
      </motion.div>
    </div>
  );
}

interface SlotProps {
  tool: DockTool;
  current: string;
  choice?: string;
  edge: DockEdge;
  tabbable: boolean;
  plateId: string;
  plateTransition: Transition;
  reflow: Transition;
  reduced: boolean;
  flyout: { open: boolean; byKey: boolean };
  hint: Hint;
  onPick: (id: string) => void;
  onFlyout: (id: string | null, byKey?: boolean) => void;
}

/** One tool: the button, the shared plate when active, and its flyout. */
function ToolSlot({
  tool,
  current,
  choice,
  edge,
  tabbable,
  plateId,
  plateTransition,
  reflow,
  reduced,
  flyout,
  hint,
  onPick,
  onFlyout,
}: SlotProps) {
  const subs = tool.tools?.length ? tool.tools : undefined;
  const shown =
    subs?.find((t) => t.id === current) ??
    subs?.find((t) => t.id === choice) ??
    subs?.[0] ??
    tool;
  const selected = shown.id === current;
  const vertical = isVertical(edge);
  const buttonRef = useRef<HTMLButtonElement>(null);
  const press = useRef<{
    timer?: ReturnType<typeof setTimeout>;
    x: number;
    y: number;
    fired: boolean;
  }>({ x: 0, y: 0, fired: false });

  useEffect(() => {
    const p = press.current;
    return () => clearTimeout(p.timer);
  }, []);

  const cancelPress = () => clearTimeout(press.current.timer);

  // A long press on a tool with sub-tools opens its flyout.
  const onPointerDown = (e: PointerEvent<HTMLButtonElement>) => {
    hint.hide();
    if (!subs || e.button !== 0) {
      return;
    }
    const p = press.current;
    p.fired = false;
    p.x = e.clientX;
    p.y = e.clientY;
    clearTimeout(p.timer);
    p.timer = setTimeout(() => {
      p.fired = true;
      onFlyout(tool.id);
    }, LONG_PRESS);
  };

  const onPointerMove = (e: PointerEvent<HTMLButtonElement>) => {
    const p = press.current;
    if (Math.hypot(e.clientX - p.x, e.clientY - p.y) > 6) {
      cancelPress();
    }
  };

  const onClick = () => {
    if (press.current.fired) {
      press.current.fired = false;
      return;
    }
    onPick(shown.id);
  };

  // The arrow across the dock opens the flyout; arrows along it rove.
  const onKeyDown = (e: KeyboardEvent<HTMLButtonElement>) => {
    const across = vertical
      ? e.key === "ArrowLeft" || e.key === "ArrowRight"
      : e.key === "ArrowUp" || e.key === "ArrowDown";
    if (subs && across) {
      e.preventDefault();
      onFlyout(tool.id, true);
    }
  };

  const close = (returnFocus: boolean) => {
    onFlyout(null);
    if (returnFocus) {
      buttonRef.current?.focus();
    }
  };

  return (
    <motion.div
      className="relative size-9 shrink-0"
      data-slot={tool.id}
      layout
      layoutDependency={vertical}
      transition={reflow}
    >
      {selected ? (
        <motion.span
          aria-hidden
          className="absolute inset-0 bg-zinc-900 dark:bg-zinc-100"
          layoutDependency={vertical}
          layoutId={plateId}
          style={{ borderRadius: 10 }}
          transition={plateTransition}
        />
      ) : null}
      <button
        aria-keyshortcuts={shown.shortcut}
        aria-label={shown.label}
        aria-pressed={selected}
        className={cn(
          "relative flex size-9 items-center justify-center rounded-[10px]",
          "transition-colors duration-150 ease-out",
          FOCUS_RING,
          selected
            ? "text-white dark:text-zinc-900"
            : "text-zinc-500 hover:bg-zinc-100 hover:text-zinc-900 dark:text-zinc-400 dark:hover:bg-zinc-800 dark:hover:text-zinc-50"
        )}
        data-dock-item
        onBlur={hint.hide}
        onClick={onClick}
        onContextMenu={subs ? (e) => e.preventDefault() : undefined}
        onFocus={(e) => {
          if (e.currentTarget.matches(":focus-visible")) {
            hint.show(e.currentTarget, shown.label, shown.shortcut);
          }
        }}
        onKeyDown={onKeyDown}
        onPointerCancel={cancelPress}
        onPointerDown={onPointerDown}
        onPointerEnter={(e) =>
          hint.show(e.currentTarget, shown.label, shown.shortcut)
        }
        onPointerLeave={() => {
          cancelPress();
          hint.hide();
        }}
        onPointerMove={onPointerMove}
        onPointerUp={cancelPress}
        ref={buttonRef}
        tabIndex={tabbable ? 0 : -1}
        type="button"
      >
        <shown.icon aria-hidden className="size-[18px]" strokeWidth={1.75} />
      </button>
      {subs ? (
        <button
          aria-expanded={flyout.open}
          aria-haspopup="menu"
          aria-label={`More ${tool.label.toLowerCase()}`}
          className={cn(
            "absolute right-[5px] bottom-[5px] flex size-2.5 items-end justify-end",
            "before:absolute before:-inset-1.5 before:content-['']",
            "transition-colors duration-150",
            selected
              ? "text-white/70 hover:text-white dark:text-zinc-900/60 dark:hover:text-zinc-900"
              : "text-zinc-400 hover:text-zinc-900 dark:text-zinc-500 dark:hover:text-zinc-50"
          )}
          onClick={() => onFlyout(flyout.open ? null : tool.id)}
          onPointerDown={hint.hide}
          tabIndex={-1}
          type="button"
        >
          <svg aria-hidden="true" className="size-[5px]" viewBox="0 0 5 5">
            <path d="M5 0V5H0Z" fill="currentColor" />
          </svg>
        </button>
      ) : null}
      <AnimatePresence>
        {subs && flyout.open ? (
          <Flyout
            current={current}
            edge={edge}
            focusOnOpen={flyout.byKey}
            key="flyout"
            onClose={close}
            onPick={(id) => {
              onPick(id);
              close(flyout.byKey);
            }}
            reduced={reduced}
            tool={tool}
          />
        ) : null}
      </AnimatePresence>
    </motion.div>
  );
}

function DotGrid() {
  const id = `dots${useId().replace(/[^a-zA-Z0-9]/g, "")}`;
  return (
    <svg
      aria-hidden="true"
      className="pointer-events-none absolute inset-0 size-full text-zinc-300 dark:text-zinc-800"
    >
      <defs>
        <pattern height="20" id={id} patternUnits="userSpaceOnUse" width="20">
          <circle cx="1" cy="1" fill="currentColor" r="1" />
        </pattern>
      </defs>
      <rect fill={`url(#${id})`} height="100%" width="100%" />
    </svg>
  );
}

interface DragState {
  dx: number;
  dy: number;
  left: number;
  top: number;
  /** Recent pointer-driven positions: `x`/`y` unclamped, `cx`/`cy` as drawn. */
  samples: { t: number; x: number; y: number; cx: number; cy: number }[];
}

/** Release velocity in px/ms: of the pointer (intent) and of the dock (as drawn). */
function releaseVelocity(samples: DragState["samples"], now: number) {
  const recent = samples.filter((s) => now - s.t <= VELOCITY_WINDOW);
  const first = recent[0];
  const last = recent.at(-1);
  if (!(first && last) || recent.length < 2) {
    return { x: 0, y: 0, cx: 0, cy: 0 };
  }
  const dt = Math.max(1, last.t - first.t);
  return {
    x: (last.x - first.x) / dt,
    y: (last.y - first.y) / dt,
    cx: (last.cx - first.cx) / dt,
    cy: (last.cy - first.cy) / dt,
  };
}

function rovingStep(key: string, vertical: boolean, i: number, n: number) {
  if (key === (vertical ? "ArrowDown" : "ArrowRight")) {
    return (i + 1) % n;
  }
  if (key === (vertical ? "ArrowUp" : "ArrowLeft")) {
    return (i - 1 + n) % n;
  }
  if (key === "Home") {
    return 0;
  }
  if (key === "End") {
    return n - 1;
  }
  return -1;
}

interface GripProps {
  vertical: boolean;
  dragging: boolean;
  tabbable: boolean;
  reflow: Transition;
  hint: Hint;
  onDown: (e: PointerEvent<HTMLButtonElement>) => void;
  onMove: (e: PointerEvent<HTMLButtonElement>) => void;
  onUp: (e: PointerEvent<HTMLButtonElement>) => void;
  onNextEdge: () => void;
}

/** The drag handle, followed by the divider that sets it apart. */
function DockGrip({
  vertical,
  dragging,
  tabbable,
  reflow,
  hint,
  onDown,
  onMove,
  onUp,
  onNextEdge,
}: GripProps) {
  const GripIcon = vertical ? GripHorizontal : GripVertical;
  return (
    <>
      <motion.div
        className="shrink-0"
        layout
        layoutDependency={vertical}
        transition={reflow}
      >
        <button
          aria-label="Move toolbar"
          className={cn(
            "flex touch-none items-center justify-center rounded-md text-zinc-400 transition-colors duration-150 hover:text-zinc-700 dark:text-zinc-500 dark:hover:text-zinc-200",
            vertical ? "h-5 w-9" : "h-9 w-5",
            dragging ? "cursor-grabbing" : "cursor-grab",
            FOCUS_RING
          )}
          data-dock-item
          onBlur={hint.hide}
          onFocus={(e) => {
            if (e.currentTarget.matches(":focus-visible")) {
              hint.show(e.currentTarget, "Drag, or Enter to move");
            }
          }}
          onKeyDown={(e) => {
            if (e.key === "Enter" || e.key === " ") {
              e.preventDefault();
              onNextEdge();
            }
          }}
          onLostPointerCapture={onUp}
          onPointerDown={onDown}
          onPointerEnter={(e) => hint.show(e.currentTarget, "Drag to dock")}
          onPointerLeave={hint.hide}
          onPointerMove={onMove}
          tabIndex={tabbable ? 0 : -1}
          type="button"
        >
          <GripIcon aria-hidden className="size-4" strokeWidth={1.75} />
        </button>
      </motion.div>
      <motion.div
        aria-hidden
        className={cn(
          "shrink-0 bg-zinc-200 dark:bg-zinc-800",
          vertical ? "my-0.5 h-px w-5" : "mx-0.5 h-5 w-px"
        )}
        layout
        layoutDependency={vertical}
        transition={reflow}
      />
    </>
  );
}

function TipBubble({
  tip,
  edge,
  reduced,
}: {
  tip: TipState;
  edge: DockEdge;
  reduced: boolean;
}) {
  return (
    <div
      aria-hidden
      className={cn("pointer-events-none absolute z-20", TIP_SHIFT[edge])}
      style={{ left: tip.x, top: tip.y }}
    >
      <motion.div
        animate={{ opacity: 1, scale: 1 }}
        className="flex items-center gap-2 whitespace-nowrap rounded-md bg-zinc-900 px-2 py-1 font-medium text-white text-xs shadow-sm dark:bg-zinc-100 dark:text-zinc-900"
        initial={
          tip.animated ? { opacity: 0, scale: reduced ? 1 : 0.96 } : false
        }
        style={{ transformOrigin: ORIGIN[edge] }}
        transition={{ duration: 0.15, ease: EASE_OUT }}
      >
        {tip.label}
        {tip.shortcut ? <Kbd>{tip.shortcut}</Kbd> : null}
      </motion.div>
    </div>
  );
}

/** Shows a tooltip group: the first tooltip waits, the rest are instant. */
function useTooltipGroup(
  dockRef: RefObject<HTMLDivElement | null>,
  edgeRef: RefObject<DockEdge>,
  blocked: RefObject<unknown>
) {
  const [tip, setTip] = useState<TipState | null>(null);
  const timer = useRef<ReturnType<typeof setTimeout> | undefined>(undefined);
  const open = useRef(false);
  const warmUntil = useRef(0);

  const hide = useCallback(() => {
    clearTimeout(timer.current);
    if (open.current) {
      warmUntil.current = performance.now() + TIP_WARM;
    }
    open.current = false;
    setTip(null);
  }, []);

  const show = useCallback(
    (el: HTMLElement, label: string, shortcut?: string) => {
      if (blocked.current) {
        return;
      }
      clearTimeout(timer.current);
      const reveal = (animated: boolean) => {
        const dock = dockRef.current;
        if (!dock) {
          return;
        }
        const pos = tipPosition(
          edgeRef.current,
          el.getBoundingClientRect(),
          dock.getBoundingClientRect()
        );
        open.current = true;
        setTip({ label, shortcut, ...pos, animated });
      };
      if (open.current || performance.now() < warmUntil.current) {
        reveal(false);
      } else {
        timer.current = setTimeout(() => reveal(true), TIP_DELAY);
      }
    },
    [dockRef, edgeRef, blocked]
  );

  useEffect(() => () => clearTimeout(timer.current), []);

  const hint = useMemo<Hint>(() => ({ show, hide }), [show, hide]);
  return { tip, hint };
}

/** A tool dock in the style of Figma or tldraw: one plate slides between tools, it can be thrown to any edge of its canvas, and it turns vertical on the sides. */
export function Toolbar({
  tools = DEFAULT_TOOLS,
  value,
  defaultValue,
  onValueChange,
  defaultEdge = "bottom",
  onEdgeChange,
  shortcuts = "scoped",
  ariaLabel = "Tools",
  className,
  dockClassName,
  children,
}: ToolbarProps) {
  const uid = useId();
  const reduced = useReducedMotion() ?? false;
  const { leaves, parentOf } = useMemo(() => flatten(tools), [tools]);
  const [innerValue, setInnerValue] = useState(
    () => defaultValue ?? leaves[0]?.id ?? ""
  );
  const current = value ?? innerValue;
  const [choices, setChoices] = useState<Record<string, string>>({});
  const [jump, setJump] = useState(false);
  const [edge, setEdge] = useState<DockEdge>(defaultEdge);
  const [measured, setMeasured] = useState(false);
  const [dragging, setDragging] = useState(false);
  const [flyout, setFlyout] = useState<{ id: string; byKey: boolean } | null>(
    null
  );
  const [focusIndex, setFocusIndex] = useState(() => {
    const top = parentOf.get(current) ?? current;
    return (
      Math.max(
        0,
        tools.findIndex((t) => t.id === top)
      ) + 1
    );
  });
  const vertical = isVertical(edge);

  const stageRef = useRef<HTMLDivElement>(null);
  const dockRef = useRef<HTMLDivElement>(null);
  const toolbarRef = useRef<HTMLDivElement>(null);
  const hoverRef = useRef(false);
  const dragRef = useRef<DragState | null>(null);
  const animsRef = useRef<AnimationPlaybackControls[]>([]);
  const pendingVelocity = useRef({ x: 0, y: 0 });
  /** The dock's size before it changed edge, to reflow from. */
  const fromSize = useRef<{ w: number; h: number } | null>(null);
  const mountedRef = useRef(false);
  const edgeRef = useRef(edge);
  edgeRef.current = edge;
  const reducedRef = useRef(reduced);
  reducedRef.current = reduced;

  const cx = useMotionValue(0);
  const cy = useMotionValue(0);
  /** Canvas and dock sizes; the drawn position never leaves the canvas. */
  const boundsRef = useRef({ W: 0, H: 0, w: 0, h: 0 });
  const transform = useTransform([cx, cy], ([x, y]: number[]) => {
    const b = boundsRef.current;
    return dockTransform(
      clamp(x ?? 0, b.w / 2, b.W - b.w / 2),
      clamp(y ?? 0, b.h / 2, b.H - b.h / 2)
    );
  });

  const { tip, hint } = useTooltipGroup(dockRef, edgeRef, dragRef);

  // ---- Selection ----
  const select = (id: string, viaKey: boolean) => {
    setJump(viaKey);
    setInnerValue(id);
    const parent = parentOf.get(id);
    if (parent) {
      setChoices((c) => ({ ...c, [parent]: id }));
    }
    if (id !== current) {
      onValueChange?.(id);
    }
  };
  const selectRef = useRef(select);
  selectRef.current = select;

  const shortcutMap = useMemo(() => {
    const map = new Map<string, string>();
    for (const leaf of leaves) {
      if (leaf.shortcut) {
        map.set(leaf.shortcut.toLowerCase(), leaf.id);
      }
    }
    return map;
  }, [leaves]);
  const keysRef = useRef({ shortcutMap, shortcuts });
  keysRef.current = { shortcutMap, shortcuts };

  // Single-key shortcuts. Keyboard actions never animate.
  useEffect(() => {
    const onKey = (e: globalThis.KeyboardEvent) => {
      const { shortcutMap: map, shortcuts: mode } = keysRef.current;
      if (e.key === "Escape") {
        setFlyout(null);
        return;
      }
      if (
        mode === "off" ||
        e.metaKey ||
        e.ctrlKey ||
        e.altKey ||
        e.repeat ||
        e.defaultPrevented ||
        isTyping(e)
      ) {
        return;
      }
      // Scoped: focus is in the stage, or the pointer is over it while
      // nothing else on the page holds focus.
      const focused = document.activeElement;
      const idle = !focused || focused === document.body;
      const inside =
        Boolean(stageRef.current?.contains(focused)) ||
        (hoverRef.current && idle);
      const id = map.get(e.key.toLowerCase());
      if (id && (mode === "global" || inside)) {
        e.preventDefault();
        selectRef.current(id, true);
      }
    };
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, []);

  // Close the flyout on a press outside its slot.
  useEffect(() => {
    if (!flyout) {
      return;
    }
    const onDown = (e: globalThis.PointerEvent) => {
      const slot =
        e.target instanceof Element ? e.target.closest("[data-slot]") : null;
      if (slot?.getAttribute("data-slot") !== flyout.id) {
        setFlyout(null);
      }
    };
    document.addEventListener("pointerdown", onDown);
    return () => document.removeEventListener("pointerdown", onDown);
  }, [flyout]);

  // ---- Docking ----
  const stopAnims = useCallback(() => {
    for (const a of animsRef.current) {
      a.stop();
    }
    animsRef.current = [];
  }, []);

  /** Moves the dock to its edge: springing with `velocity` (px/s), or at once. */
  const settle = useCallback(
    (velocity: { x: number; y: number } | null) => {
      const stage = stageRef.current;
      const dock = dockRef.current;
      if (!(stage && dock)) {
        return;
      }
      const size = { w: dock.offsetWidth, h: dock.offsetHeight };
      const W = stage.clientWidth;
      const H = stage.clientHeight;
      boundsRef.current = { W, H, ...size };
      const edgeNow = edgeRef.current;
      const target = edgeTarget(edgeNow, W, H, size.w, size.h);
      stopAnims();
      if (!velocity) {
        cx.set(target.x);
        cy.set(target.y);
        return;
      }
      const from = fromSize.current;
      fromSize.current = null;
      if (from && (from.w !== size.w || from.h !== size.h)) {
        // Turned: keep the side facing the wall where it was, and write the
        // transform now so the layout animation measures the new box there.
        const start = reflowStart(
          edgeNow,
          cx.get(),
          cy.get(),
          from,
          size,
          W,
          H
        );
        cx.set(start.x);
        cy.set(start.y);
        dock.style.transform = dockTransform(start.x, start.y);
      }
      const opts = reducedRef.current ? DOCK_TWEEN : DOCK_SPRING;
      animsRef.current = [
        animate(cx, target.x, { ...opts, velocity: velocity.x }),
        animate(cy, target.y, { ...opts, velocity: velocity.y }),
      ];
    },
    [cx, cy, stopAnims]
  );

  // Runs after the dock re-renders for its new edge, so a dock that turned
  // vertical is measured at its new size before it springs there.
  // biome-ignore lint/correctness/useExhaustiveDependencies: re-runs on each new edge
  useLayoutEffect(() => {
    if (!mountedRef.current) {
      mountedRef.current = true;
      settle(null);
      setMeasured(true);
      return;
    }
    settle(pendingVelocity.current);
    pendingVelocity.current = { x: 0, y: 0 };
  }, [edge, settle]);

  useEffect(() => {
    const stage = stageRef.current;
    if (!stage) {
      return;
    }
    const ro = new ResizeObserver(() => {
      if (!dragRef.current) {
        settle(null);
      }
    });
    ro.observe(stage);
    return () => {
      ro.disconnect();
      stopAnims();
    };
  }, [settle, stopAnims]);

  const dockTo = (next: DockEdge, velocity: { x: number; y: number }) => {
    if (next === edgeRef.current) {
      settle(velocity);
      return;
    }
    pendingVelocity.current = velocity;
    const dock = dockRef.current;
    fromSize.current = dock
      ? { w: dock.offsetWidth, h: dock.offsetHeight }
      : null;
    setJump(false);
    setEdge(next);
    onEdgeChange?.(next);
  };

  const onGripDown = (e: PointerEvent<HTMLButtonElement>) => {
    const stage = stageRef.current;
    if (e.button !== 0 || !stage) {
      return;
    }
    e.preventDefault();
    e.currentTarget.setPointerCapture(e.pointerId);
    stopAnims();
    const r = stage.getBoundingClientRect();
    // Pick up the dock where it is drawn, even mid-bounce against a wall.
    const b = boundsRef.current;
    const x = clamp(cx.get(), b.w / 2, b.W - b.w / 2);
    const y = clamp(cy.get(), b.h / 2, b.H - b.h / 2);
    cx.set(x);
    cy.set(y);
    dragRef.current = {
      dx: e.clientX - r.left - x,
      dy: e.clientY - r.top - y,
      left: r.left,
      top: r.top,
      samples: [{ t: e.timeStamp, x, y, cx: x, cy: y }],
    };
    hint.hide();
    setFlyout(null);
    setDragging(true);
  };

  const onGripMove = (e: PointerEvent<HTMLButtonElement>) => {
    const d = dragRef.current;
    const stage = stageRef.current;
    const dock = dockRef.current;
    if (!(d && stage && dock)) {
      return;
    }
    const hw = dock.offsetWidth / 2;
    const hh = dock.offsetHeight / 2;
    const x = e.clientX - d.left - d.dx;
    const y = e.clientY - d.top - d.dy;
    const drawnX = clamp(x, hw, stage.clientWidth - hw);
    const drawnY = clamp(y, hh, stage.clientHeight - hh);
    cx.set(drawnX);
    cy.set(drawnY);
    d.samples.push({ t: e.timeStamp, x, y, cx: drawnX, cy: drawnY });
    if (d.samples.length > 8) {
      d.samples.shift();
    }
  };

  // Project where the throw was headed (from the pointer, so a dock pinned
  // against a wall can still be thrown along it) and dock on the nearest edge.
  const onGripUp = (e: PointerEvent<HTMLButtonElement>) => {
    const d = dragRef.current;
    const stage = stageRef.current;
    if (!(d && stage)) {
      return;
    }
    dragRef.current = null;
    setDragging(false);
    const v = releaseVelocity(d.samples, e.timeStamp);
    const w = stage.clientWidth;
    const h = stage.clientHeight;
    const from = d.samples.at(-1) ?? { x: cx.get(), y: cy.get() };
    const px = clamp(from.x + v.x * PROJECTION, 0, w);
    const py = clamp(from.y + v.y * PROJECTION, 0, h);
    dockTo(nearestEdge(px, py, w, h), { x: v.cx * 1000, y: v.cy * 1000 });
  };

  // ---- Roving focus ----
  const dockItems = () =>
    Array.from(
      toolbarRef.current?.querySelectorAll<HTMLElement>("[data-dock-item]") ??
        []
    );

  const onToolbarKeyDown = (e: KeyboardEvent<HTMLDivElement>) => {
    const items = dockItems();
    const i = items.indexOf(e.target as HTMLElement);
    if (i === -1) {
      return;
    }
    const to = rovingStep(e.key, vertical, i, items.length);
    if (to !== -1) {
      e.preventDefault();
      items[to]?.focus();
    }
  };

  const onToolbarFocus = (e: FocusEvent<HTMLDivElement>) => {
    const i = dockItems().indexOf(e.target as HTMLElement);
    if (i !== -1) {
      setFocusIndex(i);
    }
  };

  const onFlyout = useCallback(
    (id: string | null, byKey = false) => {
      hint.hide();
      setFlyout(id ? { id, byKey } : null);
    },
    [hint]
  );

  const activeLeaf = leaves.find((l) => l.id === current);
  const plateTransition = jump || reduced ? INSTANT : PLATE_SPRING;
  const reflow = reduced ? INSTANT : REFLOW_SPRING;

  return (
    <div
      className={cn(
        "relative h-[360px] w-full overflow-hidden rounded-xl border border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-950",
        className
      )}
      data-tool={current}
      onPointerEnter={(e) => {
        hoverRef.current = e.pointerType !== "touch";
      }}
      onPointerLeave={() => {
        hoverRef.current = false;
      }}
      ref={stageRef}
      style={{ cursor: dragging ? "grabbing" : activeLeaf?.cursor }}
    >
      {children ?? <DotGrid />}
      <motion.div
        className={cn(
          "absolute z-10 cursor-auto",
          measured ? "top-0 left-0" : RESTING[edge]
        )}
        data-edge={edge}
        ref={dockRef}
        style={measured ? { transform } : undefined}
      >
        <motion.div
          aria-label={ariaLabel}
          aria-orientation={vertical ? "vertical" : "horizontal"}
          className={cn(
            "flex items-center gap-0.5 border border-zinc-200 bg-white p-1 dark:border-zinc-800 dark:bg-zinc-900",
            "transition-shadow duration-200 ease-out",
            vertical && "flex-col",
            dragging
              ? "shadow-[0_12px_32px_-8px_rgb(0_0_0/0.25)]"
              : "shadow-[0_4px_16px_-6px_rgb(0_0_0/0.15)]",
            jump && "[&_*]:transition-none",
            dockClassName
          )}
          layout
          layoutDependency={vertical}
          onFocus={onToolbarFocus}
          onKeyDown={onToolbarKeyDown}
          ref={toolbarRef}
          role="toolbar"
          style={{ borderRadius: 14 }}
          transition={reflow}
        >
          <DockGrip
            dragging={dragging}
            hint={hint}
            onDown={onGripDown}
            onMove={onGripMove}
            onNextEdge={() =>
              dockTo(NEXT_EDGE[edgeRef.current], { x: 0, y: 0 })
            }
            onUp={onGripUp}
            reflow={reflow}
            tabbable={focusIndex === 0}
            vertical={vertical}
          />
          {tools.map((tool, index) => (
            <ToolSlot
              choice={choices[tool.id]}
              current={current}
              edge={edge}
              flyout={{
                open: flyout?.id === tool.id,
                byKey: flyout?.id === tool.id && flyout.byKey,
              }}
              hint={hint}
              key={tool.id}
              onFlyout={onFlyout}
              onPick={(id) => select(id, false)}
              plateId={`${uid}-plate`}
              plateTransition={plateTransition}
              reduced={reduced}
              reflow={reflow}
              tabbable={focusIndex === index + 1}
              tool={tool}
            />
          ))}
        </motion.div>

        {tip ? <TipBubble edge={edge} reduced={reduced} tip={tip} /> : null}
      </motion.div>
    </div>
  );
}

export default Toolbar;
```


---

# Cradle Text
> A headline hung like a Newton's cradle, so a knock on one letter clacks through the word, built with React and pendulum physics.

Source: https://kokonutui.com/docs/texts/cradle-text

## Installation

```bash
npx shadcn@latest add @kokonutui/cradle-text
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Cradle Text
 * @version: 1.0.0
 * @date: 2026-10-15
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface CradleTextProps {
  /** The line of letters hung from the rail. Keep it to one line. */
  text?: string;
  className?: string;
  /** Lift the first letter and let it go once, the first time it's seen. */
  intro?: boolean;
  /** How much speed a collision keeps, 0 to 1. Steel is about 0.95. */
  bounce?: number;
}

// Every letter hangs from the rail on a thread, a pendulum of the same
// length, so it swings like the balls of a Newton's cradle: letters that
// touch pass the knock along, and the one at the far end flies out.
const SUBSTEPS = 8;
const ITERATIONS = 3;
// One full swing takes this long, whatever the font size: a desk toy with
// strings about 12 cm long.
const PERIOD = 0.72;
// Air drag, per second. Most of the energy is lost in the clacks; the last
// small sway is damped harder so the cradle comes to rest in seconds.
const DRAG = 0.3;
const SETTLE_DRAG = 1.6;
const SETTLE_BELOW = 0.02;
// Furthest a letter can be pulled out, in radians.
const MAX_ANGLE = 1.15;
// A cursor sweeping through a letter knocks it, per px/s of its speed.
const SWEEP_PUSH = 0.22;
const MAX_SWEEP = 900;
// A tap sends a letter out to about this angle.
const TAP_ANGLE = 0.38;
// The intro pulls the first letter out this far, then lets go.
const INTRO_ANGLE = 0.62;
const INTRO_PULL = 520;
// Below this energy (radians, roughly) the cradle is at rest.
const REST = 0.0004;

interface Bob {
  el: HTMLElement;
  /** Ink edges and centre, in stage px, with the letter hanging still. */
  left: number;
  right: number;
  center: number;
  top: number;
  bottom: number;
  /** Where the letter's own box sits, to rotate it about its pivot. */
  boxLeft: number;
  boxTop: number;
  /** Space to the next letter at rest; they collide when it closes. */
  gap: number;
  phi: number;
  omega: number;
  held: boolean;
}

function clamp(x: number, min: number, max: number) {
  return Math.min(Math.max(x, min), max);
}

function easeOut(t: number) {
  return 1 - (1 - t) ** 4;
}

export default function CradleText({
  text = "Momentum",
  className,
  intro = true,
  bounce = 0.97,
}: CradleTextProps) {
  const stageRef = useRef<HTMLDivElement>(null);
  const lettersRef = useRef<HTMLSpanElement>(null);
  const railRef = useRef<HTMLSpanElement>(null);

  useEffect(() => {
    const stage = stageRef.current;
    const lettersEl = lettersRef.current;
    const rail = railRef.current;
    const ink = document.createElement("canvas").getContext("2d");
    if (!(stage && lettersEl && rail && ink)) {
      return;
    }

    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const spans = Array.from(
      lettersEl.querySelectorAll<HTMLElement>("[data-letter]")
    );
    const restitution = clamp(bounce, 0, 1);
    const w0 = (2 * Math.PI) / PERIOD;

    let bobs: Bob[] = [];
    // Pivot height and the swing radius, measured to the letters' middle.
    let railY = 0;
    let radius = 1;
    let raf = 0;
    let last = 0;
    let visible = true;
    let pull: { bob: Bob; start: number; to: number } | null = null;
    let hand: {
      id: number;
      bob: Bob;
      startX: number;
      startTime: number;
      moved: boolean;
      prev: number;
      prevTime: number;
      spin: number;
    } | null = null;
    let sweep: { x: number; t: number; over: Bob | null } | null = null;

    const measure = () => {
      const stageBox = stage.getBoundingClientRect();
      const probe = lettersEl.lastElementChild as HTMLElement;
      const baseline = probe.getBoundingClientRect().bottom - stageBox.top;
      const style = getComputedStyle(lettersEl);
      const em = Number.parseFloat(style.fontSize);
      ink.font = style.font;
      railY = rail.getBoundingClientRect().top - stageBox.top + 0.5;
      radius = Math.max(baseline - em * 0.35 - railY, 1);
      bobs = spans.map((el) => {
        el.style.transform = "";
        const box = el.getBoundingClientRect();
        const m = ink.measureText(el.dataset.letter ?? "");
        const boxLeft = box.left - stageBox.left;
        const left = boxLeft - m.actualBoundingBoxLeft;
        const right = boxLeft + m.actualBoundingBoxRight;
        const top = baseline - m.actualBoundingBoxAscent;
        const center = (left + right) / 2;
        // The thread runs from the rail to the top of the ink.
        const thread = el.firstElementChild as HTMLElement;
        thread.style.left = `${center - boxLeft - 0.5}px`;
        thread.style.top = `${railY - (box.top - stageBox.top)}px`;
        thread.style.height = `${Math.max(top - railY, 0)}px`;
        return {
          el,
          left,
          right,
          center,
          top,
          bottom: baseline + m.actualBoundingBoxDescent,
          boxLeft,
          boxTop: box.top - stageBox.top,
          gap: 0,
          phi: 0,
          omega: 0,
          held: false,
        };
      });
      for (let i = 0; i + 1 < bobs.length; i++) {
        bobs[i].gap = Math.max(bobs[i + 1].left - bobs[i].right, 0);
      }
      pull = null;
      hand = null;
    };

    const draw = () => {
      for (const bob of bobs) {
        if (bob.phi === 0) {
          bob.el.style.transform = "";
          continue;
        }
        const px = bob.center - bob.boxLeft;
        const py = railY - bob.boxTop;
        // Swinging right turns the letter counter-clockwise about the rail.
        bob.el.style.transform = `translate3d(${px.toFixed(2)}px, ${py.toFixed(2)}px, 0) rotate(${(-bob.phi).toFixed(4)}rad) translate3d(${(-px).toFixed(2)}px, ${(-py).toFixed(2)}px, 0)`;
      }
    };

    const energy = () =>
      bobs.reduce(
        (e, b) => e + (b.omega / w0) ** 2 + 2 * (1 - Math.cos(b.phi)),
        0
      );

    /** Bounce two touching letters apart if they're closing. */
    const bounceApart = (a: Bob, b: Bob, wa: number, wb: number) => {
      const ca = Math.max(Math.cos(a.phi), 0.2);
      const cb = Math.max(Math.cos(b.phi), 0.2);
      const va = a.omega * radius * ca;
      const vb = b.omega * radius * cb;
      const closing = va - vb;
      if (closing <= 0) {
        return;
      }
      const impulse = ((1 + restitution) * closing) / (wa + wb);
      // A held letter (weight 0) keeps the hand's speed.
      a.omega = (va - wa * impulse) / (radius * ca);
      b.omega = (vb + wb * impulse) / (radius * cb);
    };

    /** Separate two letters that overlap and bounce them if they're closing. */
    const collide = (a: Bob, b: Bob) => {
      const xa = radius * Math.sin(a.phi);
      const xb = radius * Math.sin(b.phi);
      const depth = xa - xb - a.gap;
      const wa = a.held ? 0 : 1;
      const wb = b.held ? 0 : 1;
      if (depth <= 0 || wa + wb === 0) {
        return;
      }
      const share = depth / (wa + wb);
      a.phi = Math.asin(clamp((xa - wa * share) / radius, -1, 1));
      b.phi = Math.asin(clamp((xb + wb * share) / radius, -1, 1));
      bounceApart(a, b, wa, wb);
    };

    const swing = (h: number, drag: number) => {
      for (const bob of bobs) {
        if (!bob.held) {
          bob.omega -= w0 * w0 * Math.sin(bob.phi) * h;
          bob.omega *= 1 - drag * h;
          bob.phi += bob.omega * h;
        }
      }
    };

    const step = (dt: number) => {
      const h = dt / SUBSTEPS;
      const drag = energy() < SETTLE_BELOW ? SETTLE_DRAG : DRAG;
      for (let s = 0; s < SUBSTEPS; s++) {
        swing(h, drag);
        // Sweep both ways so a knock travels the whole row in one step,
        // the way it does through a real cradle.
        for (let it = 0; it < ITERATIONS; it++) {
          for (let i = 0; i + 1 < bobs.length; i++) {
            collide(bobs[i], bobs[i + 1]);
          }
          for (let i = bobs.length - 2; i >= 0; i--) {
            collide(bobs[i], bobs[i + 1]);
          }
        }
      }
    };

    const runPull = (now: number) => {
      if (!pull) {
        return;
      }
      const t = (now - pull.start) / INTRO_PULL;
      if (t >= 1.25) {
        pull.bob.held = false;
        pull.bob.omega = 0;
        pull = null;
        return;
      }
      pull.bob.held = true;
      pull.bob.phi = pull.to * easeOut(Math.min(t, 1));
      pull.bob.omega = 0;
    };

    const frame = (now: number) => {
      raf = 0;
      if (!visible) {
        return;
      }
      const dt = last ? Math.min((now - last) / 1000, 1 / 30) : 1 / 60;
      last = now;
      runPull(now);
      step(dt);
      draw();
      if (hand || pull || energy() > REST) {
        raf = requestAnimationFrame(frame);
        return;
      }
      for (const bob of bobs) {
        bob.phi = 0;
        bob.omega = 0;
      }
      draw();
    };

    const start = () => {
      if (!raf && visible) {
        last = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    /** Pointer in stage px. */
    const local = (event: PointerEvent) => {
      const r = stage.getBoundingClientRect();
      return { x: event.clientX - r.left, y: event.clientY - r.top };
    };

    /** The letter under the pointer, where it hangs right now. */
    const bobAt = (x: number, y: number, slack: number) =>
      bobs.find((bob) => {
        const shift = radius * Math.sin(bob.phi);
        return (
          x > bob.left + shift - slack &&
          x < bob.right + shift + slack &&
          y > bob.top - slack &&
          y < bob.bottom + slack
        );
      });

    const onDown = (event: PointerEvent) => {
      if (hand || event.button !== 0) {
        return;
      }
      const p = local(event);
      const em = Number.parseFloat(getComputedStyle(lettersEl).fontSize);
      const bob = bobAt(p.x, p.y, em * 0.1);
      if (!bob) {
        return;
      }
      stage.setPointerCapture(event.pointerId);
      pull = null;
      bob.held = true;
      bob.omega = 0;
      hand = {
        id: event.pointerId,
        bob,
        startX: p.x - radius * Math.sin(bob.phi),
        startTime: event.timeStamp,
        moved: false,
        prev: bob.phi,
        prevTime: event.timeStamp,
        spin: 0,
      };
      stage.dataset.grabbing = "";
      start();
    };

    const onMove = (event: PointerEvent) => {
      const p = local(event);
      if (hand && event.pointerId === hand.id) {
        const dx = p.x - hand.startX;
        if (Math.abs(dx) > 3) {
          hand.moved = true;
        }
        // The letter follows the finger sideways along its arc.
        const phi = Math.asin(
          clamp(dx / radius, -Math.sin(MAX_ANGLE), Math.sin(MAX_ANGLE))
        );
        const dt = Math.max(event.timeStamp - hand.prevTime, 8) / 1000;
        const spin = (phi - hand.prev) / dt;
        hand.spin = hand.spin * 0.4 + spin * 0.6;
        hand.prev = phi;
        hand.prevTime = event.timeStamp;
        hand.bob.phi = phi;
        // Carried into its neighbours, the hand pushes them along.
        hand.bob.omega = hand.spin;
        start();
        return;
      }
      if (event.pointerType !== "mouse") {
        sweep = null;
        return;
      }
      const over = bobAt(p.x, p.y, 0) ?? null;
      if (sweep && over && over !== sweep.over && !over.held) {
        // Brushing through a letter knocks it the way the cursor moved.
        const dt = Math.max(event.timeStamp - sweep.t, 8) / 1000;
        const vx = clamp((p.x - sweep.x) / dt, -MAX_SWEEP, MAX_SWEEP);
        over.omega += (SWEEP_PUSH * vx) / radius;
        pull = null;
        start();
      }
      sweep = { x: p.x, t: event.timeStamp, over };
    };

    const onUp = (event: PointerEvent) => {
      if (!hand || event.pointerId !== hand.id) {
        return;
      }
      const { bob } = hand;
      bob.held = false;
      delete stage.dataset.grabbing;
      if (hand.moved) {
        // Let go from still if the hand stopped before releasing.
        const idle = event.timeStamp - hand.prevTime > 60;
        bob.omega = idle ? 0 : clamp(hand.spin, -w0 * 1.5, w0 * 1.5);
      } else {
        // A tap knocks the letter away from the side it was tapped on.
        const p = local(event);
        const side = p.x < bob.center + radius * Math.sin(bob.phi) ? 1 : -1;
        bob.omega += side * w0 * TAP_ANGLE;
      }
      hand = null;
      start();
    };

    const onLeave = () => {
      sweep = null;
    };

    measure();
    draw();

    let width = stage.clientWidth;
    const resizeObserver = new ResizeObserver(() => {
      if (stage.clientWidth === width) {
        return;
      }
      width = stage.clientWidth;
      measure();
      draw();
    });
    resizeObserver.observe(stage);
    document.fonts?.ready.then(() => {
      measure();
      draw();
    });

    let greeted = !intro || reduceMotion;
    let greetTimer = 0;
    const intersection = new IntersectionObserver(
      ([entry]) => {
        visible =
          entry.isIntersecting && document.visibilityState === "visible";
        if (!visible) {
          return;
        }
        if (!greeted && entry.intersectionRatio > 0.6) {
          greeted = true;
          greetTimer = window.setTimeout(() => {
            const first = bobs[0];
            if (first && !hand) {
              pull = { bob: first, start: performance.now(), to: -INTRO_ANGLE };
              start();
            }
          }, 400);
        }
        start();
      },
      { threshold: [0, 0.6] }
    );
    intersection.observe(stage);
    const onVisibility = () => {
      visible = document.visibilityState === "visible";
      if (visible) {
        start();
      }
    };
    document.addEventListener("visibilitychange", onVisibility);

    if (!reduceMotion) {
      stage.addEventListener("pointerdown", onDown);
      stage.addEventListener("pointermove", onMove);
      stage.addEventListener("pointerup", onUp);
      stage.addEventListener("pointercancel", onUp);
      stage.addEventListener("pointerleave", onLeave);
    }

    return () => {
      cancelAnimationFrame(raf);
      window.clearTimeout(greetTimer);
      resizeObserver.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      stage.removeEventListener("pointerdown", onDown);
      stage.removeEventListener("pointermove", onMove);
      stage.removeEventListener("pointerup", onUp);
      stage.removeEventListener("pointercancel", onUp);
      stage.removeEventListener("pointerleave", onLeave);
    };
  }, [intro, bounce]);

  return (
    <div className={cn("@container flex w-full justify-center", className)}>
      <div
        className="relative cursor-grab touch-pan-y select-none px-[0.9em] pt-[1.5em] pb-[0.45em] font-semibold text-[clamp(2rem,11cqi,6rem)] text-zinc-900 leading-none tracking-tight data-[grabbing]:cursor-grabbing dark:text-zinc-100"
        ref={stageRef}
      >
        <span className="sr-only">{text}</span>
        {/* The rail the letters hang from. */}
        <span
          aria-hidden="true"
          className="pointer-events-none absolute inset-x-0 top-[0.3em] h-px bg-zinc-300 dark:bg-zinc-700"
          ref={railRef}
        />
        <span
          aria-hidden="true"
          className="relative block whitespace-pre"
          ref={lettersRef}
        >
          {Array.from(text).map((char, index) =>
            char === " " ? (
              // biome-ignore lint/suspicious/noArrayIndexKey: letters repeat; their position is their identity.
              <span className="inline-block w-[0.32em]" key={index} />
            ) : (
              <span
                className="relative inline-block origin-top-left will-change-transform"
                data-letter={char}
                // biome-ignore lint/suspicious/noArrayIndexKey: letters repeat; their position is their identity.
                key={index}
              >
                <span className="absolute w-px bg-zinc-300 dark:bg-zinc-600" />
                {char}
              </span>
            )
          )}
          <span className="inline-block h-0 w-0" />
        </span>
      </div>
    </div>
  );
}
```


---

# Dynamic Text
> Morphing text where shared letters travel, old ones fall and new ones land, with decode and cycle modes.

Source: https://kokonutui.com/docs/texts/dynamic-text

## Installation

```bash
npx shadcn@latest add @kokonutui/dynamic-text
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Dynamic Text. Morphing text where letters are physical
 * objects: shared letters travel to their new place on a spring arc, leaving
 * letters fall off the baseline, entering letters drop in and land, and digits
 * roll like a counter. Also has a `decode` mode (cells scramble and lock left
 * to right) and a `cycle` mode (the greeting rhythm).
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type RefObject,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface Greeting {
  text: string;
  /** BCP 47 language tag, so screen readers pronounce each word correctly. */
  lang?: string;
}

export type DynamicTextMode = "morph" | "decode" | "cycle";

export interface DynamicTextProps {
  /**
   * `morph`: letters travel, fall and land. `decode`: monospace cells scramble
   * and lock left to right. `cycle`: morphs through `words` with a greeting
   * rhythm (a long first word, faster middle words, a hold on the last).
   */
  mode?: DynamicTextMode;
  /** The string to show. Change it to animate. When set, `words` is ignored. */
  text?: string;
  /** Words to rotate through when `text` is not set. */
  words?: (string | Greeting)[];
  /**
   * Milliseconds each word holds. In `cycle` mode this is the first word's
   * hold; the middle words speed up from there.
   */
  interval?: number;
  /** Start over after the last word. Defaults to true, except in `cycle`. */
  loop?: boolean;
  /** Called once the last word is shown. Never called when looping. */
  onComplete?: () => void;
  className?: string;
}

const MORPH_WORDS = ["Create", "Iterate", "Repeat", "Ship"];
const DECODE_WORDS = ["Hello, world", "Build 4096 ready", "All systems go"];
const GREETINGS: Greeting[] = [
  { text: "Hello", lang: "en" },
  { text: "こんにちは", lang: "ja" },
  { text: "Bonjour", lang: "fr" },
  { text: "Hola", lang: "es" },
  { text: "안녕하세요", lang: "ko" },
  { text: "Ciao", lang: "it" },
  { text: "Hallo", lang: "de" },
  { text: "Hello", lang: "en" },
];

const DEFAULT_WORDS: Record<DynamicTextMode, (string | Greeting)[]> = {
  morph: MORPH_WORDS,
  decode: DECODE_WORDS,
  cycle: GREETINGS,
};
const DEFAULT_INTERVAL: Record<DynamicTextMode, number> = {
  morph: 2200,
  decode: 2800,
  cycle: 900,
};

/* Text helpers ---------------------------------------------------------- */

const segmenter =
  typeof Intl !== "undefined" && "Segmenter" in Intl
    ? new Intl.Segmenter(undefined, { granularity: "grapheme" })
    : null;

/** Splits into user-perceived characters, so emoji and Hangul stay whole. */
function splitGraphemes(value: string): string[] {
  return segmenter
    ? Array.from(segmenter.segment(value), (s) => s.segment)
    : Array.from(value);
}

const isDigit = (char: string) => char >= "0" && char <= "9";
const isBlank = (char: string) => char.trim() === "";
const clamp01 = (n: number) => Math.min(1, Math.max(0, n));

function toGreeting(word: string | Greeting): Greeting {
  return typeof word === "string" ? { text: word } : word;
}

/** How long word `index` of `count` holds before the next one. */
function holdFor(
  mode: DynamicTextMode,
  index: number,
  count: number,
  interval: number
) {
  if (mode !== "cycle") {
    return interval;
  }
  if (index === 0) {
    return interval;
  }
  if (index === count - 1) {
    return interval * 2;
  }
  // The middle words accelerate, like someone getting into the rhythm.
  return Math.max(90, interval * 0.36 * 0.8 ** (index - 1));
}

function useReducedMotionRef() {
  const ref = useRef(false);
  useEffect(() => {
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    const sync = () => {
      ref.current = query.matches;
    };
    sync();
    query.addEventListener("change", sync);
    return () => query.removeEventListener("change", sync);
  }, []);
  return ref;
}

/** True while the element is on screen and the tab is visible. */
function useRunning(ref: RefObject<HTMLElement | null>) {
  const [running, setRunning] = useState(false);
  useEffect(() => {
    const el = ref.current;
    if (!el) {
      return;
    }
    let inView = false;
    const sync = () =>
      setRunning(inView && document.visibilityState === "visible");
    const observer = new IntersectionObserver((entries) => {
      inView = entries.some((e) => e.isIntersecting);
      sync();
    });
    observer.observe(el);
    document.addEventListener("visibilitychange", sync);
    return () => {
      observer.disconnect();
      document.removeEventListener("visibilitychange", sync);
    };
  }, [ref]);
  return running;
}

/* Morph physics --------------------------------------------------------- */

type Phase = "rest" | "travel" | "drop" | "fall" | "roll" | "fade";

interface Glyph {
  id: number;
  char: string;
  digit: boolean;
  /** Digit position counted from the right, so prices roll like counters. */
  slot: number;
  el: HTMLSpanElement | null;
  phase: Phase;
  leaving: boolean;
  delay: number;
  x: number;
  vx: number;
  tx: number;
  x0: number;
  arc: number;
  y: number;
  vy: number;
  ty: number;
  r: number;
  vr: number;
  tr: number;
  sq: number;
  vsq: number;
  o: number;
}

interface Token {
  char: string;
  x: number;
  digit: boolean;
  slot: number;
}

interface GlyphView {
  id: number;
  char: string;
}

const STEP = 1 / 120;
const damping = (k: number, zeta: number) => 2 * zeta * Math.sqrt(k);
const TRAVEL_K = 140;
const TRAVEL_C = damping(TRAVEL_K, 0.8);
const LIFT_K = 300;
const LIFT_C = damping(LIFT_K, 0.9);
const ROLL_K = 200;
const ROLL_C = damping(ROLL_K, 0.86);
const SQUASH_K = 1400;
const SQUASH_C = damping(SQUASH_K, 0.6);
const TILT_K = 140;
const TILT_C = damping(TILT_K, 0.7);
const WIDTH_K = 220;
const WIDTH_C = damping(WIDTH_K, 1);
/** Distances below are in em, so the motion scales with the font. */
const GRAVITY = 32;
const DROP = 0.7;
const FALL_FADE = 0.9;
const ROLL = 0.75;
const LAND_SQUASH = -0.16;
const ENTER_STAGGER = 0.035;
/** Long strings share this much stagger, so the last letter isn't late. */
const MAX_ENTER_SPREAD = 0.45;
const FADE_RATE = 7;

function paint(g: Glyph) {
  if (!g.el) {
    return;
  }
  const sy = 1 + g.sq;
  const sx = 1 - g.sq * 0.6;
  g.el.style.transform = `translate3d(${g.x.toFixed(2)}px, ${g.y.toFixed(2)}px, 0) rotate(${g.r.toFixed(2)}deg) scale(${sx.toFixed(3)}, ${sy.toFixed(3)})`;
  g.el.style.opacity = g.o.toFixed(3);
}

function stepSquash(g: Glyph, h: number) {
  if (g.sq === 0 && g.vsq === 0) {
    return;
  }
  g.vsq += (-SQUASH_K * g.sq - SQUASH_C * g.vsq) * h;
  g.sq += g.vsq * h;
  if (Math.abs(g.sq) < 0.001 && Math.abs(g.vsq) < 0.01) {
    g.sq = 0;
    g.vsq = 0;
  }
}

function stepTravel(g: Glyph, h: number) {
  // Lift along a shallow arc that peaks halfway, so crossing letters pass
  // over and under each other instead of through.
  const span = Math.abs(g.tx - g.x0);
  const p = span < 0.5 ? 1 : clamp01(1 - Math.abs(g.tx - g.x) / span);
  g.ty = g.arc * 4 * p * (1 - p);
  g.vx += (-TRAVEL_K * (g.x - g.tx) - TRAVEL_C * g.vx) * h;
  g.x += g.vx * h;
  g.vy += (-LIFT_K * (g.y - g.ty) - LIFT_C * g.vy) * h;
  g.y += g.vy * h;
  g.o = Math.min(1, g.o + FADE_RATE * h);
}

function stepDrop(g: Glyph, h: number, em: number) {
  g.vy += GRAVITY * em * h;
  g.y += g.vy * h;
  if (g.y >= 0) {
    // Landing: one squash, then the spring takes it back.
    g.y = 0;
    g.vy = 0;
    g.sq = LAND_SQUASH;
    g.phase = "rest";
  }
  g.o = clamp01(1 + g.y / (DROP * em));
}

function stepFall(g: Glyph, h: number, em: number) {
  g.vy += GRAVITY * em * h;
  g.y += g.vy * h;
  g.x += g.vx * h;
  g.vr += (-TILT_K * (g.r - g.tr) - TILT_C * g.vr) * h;
  g.r += g.vr * h;
  g.o = Math.min(g.o, clamp01(1 - g.y / (FALL_FADE * em)));
}

function stepRoll(g: Glyph, h: number, em: number) {
  g.vy += (-ROLL_K * (g.y - g.ty) - ROLL_C * g.vy) * h;
  g.y += g.vy * h;
  g.o = clamp01(1 - Math.abs(g.y) / (ROLL * em));
}

function stepFade(g: Glyph, h: number) {
  g.o = clamp01(g.o + (g.leaving ? -FADE_RATE : FADE_RATE) * h);
}

function stepGlyph(g: Glyph, h: number, em: number) {
  switch (g.phase) {
    case "travel":
      stepTravel(g, h);
      break;
    case "drop":
      stepDrop(g, h, em);
      break;
    case "fall":
      stepFall(g, h, em);
      break;
    case "roll":
      stepRoll(g, h, em);
      break;
    case "fade":
      stepFade(g, h);
      break;
    default:
      break;
  }
  stepSquash(g, h);
}

const isGone = (g: Glyph) => g.leaving && g.o <= 0.002;

/** Moves a glyph into rest once it has arrived. Returns true while moving. */
function settle(g: Glyph): boolean {
  if (g.leaving) {
    return !isGone(g);
  }
  const arrived =
    Math.abs(g.x - g.tx) < 0.05 &&
    Math.abs(g.vx) < 0.5 &&
    Math.abs(g.y) < 0.05 &&
    Math.abs(g.vy) < 0.5;
  const done =
    (g.phase === "travel" && arrived) ||
    (g.phase === "roll" && arrived) ||
    (g.phase === "fade" && g.o >= 1);
  if (done) {
    g.x = g.tx;
    g.y = 0;
    g.vx = 0;
    g.vy = 0;
    g.o = 1;
    g.phase = "rest";
  }
  return g.phase !== "rest" || g.sq !== 0;
}

/** Direction digits roll: 1 when the number grew (old goes up, new comes up). */
function rollDirection(previous: Glyph[], tokens: Token[]) {
  const before = Number(
    previous
      .filter((g) => g.digit)
      .map((g) => g.char)
      .join("")
  );
  const after = Number(
    tokens
      .filter((t) => t.digit)
      .map((t) => t.char)
      .join("")
  );
  return after < before ? -1 : 1;
}

/** Squeezes the entering stagger so a long string doesn't trickle in. */
function capStagger(glyphs: Glyph[], entering: number) {
  const spread = entering * ENTER_STAGGER;
  if (spread <= MAX_ENTER_SPREAD) {
    return;
  }
  for (const g of glyphs) {
    g.delay *= MAX_ENTER_SPREAD / spread;
  }
}

class MorphEngine {
  glyphs: Glyph[] = [];
  /** The glyphs that spell the current text, in order. */
  order: Glyph[] = [];
  root: HTMLSpanElement | null = null;
  onChange: (() => void) | null = null;
  reduced = false;
  started = false;
  em = 16;
  w = 0;
  vw = 0;
  tw = 0;
  private nextId = 0;
  private raf = 0;
  private last = 0;
  private readonly refs = new Map<
    number,
    (el: HTMLSpanElement | null) => void
  >();

  views(): GlyphView[] {
    return this.glyphs.map((g) => ({ id: g.id, char: g.char }));
  }

  refFor(id: number) {
    let ref = this.refs.get(id);
    if (!ref) {
      ref = (el: HTMLSpanElement | null) => {
        const glyph = this.glyphs.find((g) => g.id === id);
        if (glyph) {
          glyph.el = el;
          paint(glyph);
        }
      };
      this.refs.set(id, ref);
    }
    return ref;
  }

  private create(t: Token): Glyph {
    const glyph: Glyph = {
      id: this.nextId++,
      char: t.char,
      digit: t.digit,
      slot: t.slot,
      el: null,
      phase: "rest",
      leaving: false,
      delay: 0,
      x: t.x,
      vx: 0,
      tx: t.x,
      x0: t.x,
      arc: 0,
      y: 0,
      vy: 0,
      ty: 0,
      r: 0,
      vr: 0,
      tr: 0,
      sq: 0,
      vsq: 0,
      o: 1,
    };
    this.glyphs.push(glyph);
    return glyph;
  }

  private move(g: Glyph, t: Token, instant: boolean) {
    g.slot = t.slot;
    g.tx = t.x;
    if (instant) {
      g.x = t.x;
      g.y = 0;
      g.vx = 0;
      g.vy = 0;
      g.phase = g.o < 1 ? "fade" : "rest";
      return;
    }
    if (g.phase === "rest" && Math.abs(t.x - g.x) < 0.5) {
      g.x = t.x;
      return;
    }
    // Redirects keep the current position and velocity: no restart.
    g.x0 = g.x;
    g.delay = 0;
    const distance = t.x - g.x;
    g.arc =
      -Math.sign(distance) *
      Math.min(0.22 * this.em, Math.abs(distance) * 0.14);
    g.phase = "travel";
  }

  private enter(g: Glyph, dir: number, instant: boolean, index: number) {
    g.o = 0;
    if (instant) {
      g.phase = "fade";
      return;
    }
    if (g.digit) {
      g.y = dir * ROLL * this.em;
      g.ty = 0;
      g.phase = "roll";
      return;
    }
    g.y = -DROP * this.em;
    g.phase = "drop";
    g.delay = index * ENTER_STAGGER;
  }

  private leave(g: Glyph, dir: number, instant: boolean) {
    g.leaving = true;
    g.delay = 0;
    if (instant) {
      g.phase = "fade";
      return;
    }
    if (g.digit) {
      g.phase = "roll";
      g.ty = -dir * ROLL * 1.2 * this.em;
      return;
    }
    // Tip toward the side it sits on, 5-15°, and drift that way a little.
    const side = g.x + this.em * 0.3 < this.tw / 2 ? -1 : 1;
    g.tr = side * (5 + ((g.id * 7) % 11));
    g.vx = side * 0.4 * this.em;
    g.vy = Math.max(g.vy, 0);
    g.phase = "fall";
  }

  /** Re-places the current text after a resize or a font load. */
  place(tokens: Token[], width: number) {
    if (tokens.length !== this.order.length) {
      return;
    }
    tokens.forEach((t, i) => {
      const g = this.order[i];
      if (g) {
        g.tx = t.x;
        if (g.phase === "rest") {
          g.x = t.x;
          paint(g);
        }
      }
    });
    this.tw = width;
    if (!this.raf) {
      this.w = width;
      this.paintWidth();
    }
  }

  update(tokens: Token[], width: number) {
    if (!this.started) {
      // First paint: put everything in place, no animation.
      this.started = true;
      this.order = tokens.map((t) => this.create(t));
      this.w = width;
      this.tw = width;
      this.paintWidth();
      return;
    }
    const instant = this.reduced;
    const letters = new Map<string, Glyph[]>();
    const slots = new Map<number, Glyph>();
    for (const g of this.order) {
      if (g.digit) {
        slots.set(g.slot, g);
      } else {
        letters.set(g.char, [...(letters.get(g.char) ?? []), g]);
      }
    }
    const dir = rollDirection(this.order, tokens);
    const next: Glyph[] = [];
    let entering = 0;
    for (const t of tokens) {
      let old: Glyph | undefined;
      if (t.digit) {
        old = slots.get(t.slot);
        slots.delete(t.slot);
      } else {
        old = letters.get(t.char)?.shift();
      }
      if (old && old.char === t.char) {
        this.move(old, t, instant);
        next.push(old);
        continue;
      }
      if (old) {
        this.leave(old, dir, instant);
      }
      const g = this.create(t);
      this.enter(g, dir, instant, entering++);
      next.push(g);
    }
    capStagger(next, entering);
    for (const list of letters.values()) {
      for (const g of list) {
        this.leave(g, dir, instant);
      }
    }
    for (const g of slots.values()) {
      this.leave(g, dir, instant);
    }
    this.order = next;
    this.tw = width;
    if (instant) {
      this.w = width;
      this.vw = 0;
      this.paintWidth();
    }
  }

  private paintWidth() {
    if (this.root) {
      this.root.style.width = `${this.w.toFixed(2)}px`;
    }
  }

  private stepWidth(dt: number) {
    if (Math.abs(this.w - this.tw) < 0.1 && Math.abs(this.vw) < 0.1) {
      if (this.w !== this.tw) {
        this.w = this.tw;
        this.vw = 0;
        this.paintWidth();
      }
      return false;
    }
    let t = dt;
    while (t > 1e-6) {
      const h = Math.min(STEP, t);
      this.vw += (-WIDTH_K * (this.w - this.tw) - WIDTH_C * this.vw) * h;
      this.w += this.vw * h;
      t -= h;
    }
    this.paintWidth();
    return true;
  }

  private stepAll(dt: number) {
    let moving = false;
    for (const g of this.glyphs) {
      if (g.delay > 0) {
        g.delay -= dt;
        moving = true;
        continue;
      }
      let t = dt;
      while (t > 1e-6) {
        const h = Math.min(STEP, t);
        stepGlyph(g, h, this.em);
        t -= h;
      }
      if (settle(g)) {
        moving = true;
      }
      paint(g);
    }
    return moving;
  }

  private readonly tick = (now: number) => {
    const dt = this.last ? Math.min(0.05, (now - this.last) / 1000) : 1 / 60;
    this.last = now;
    const moving = this.stepAll(dt);
    const resizing = this.stepWidth(dt);
    if (this.glyphs.some(isGone)) {
      for (const g of this.glyphs) {
        if (isGone(g)) {
          this.refs.delete(g.id);
        }
      }
      this.glyphs = this.glyphs.filter((g) => !isGone(g));
      this.onChange?.();
    }
    // Sleep once everything has settled.
    this.raf = moving || resizing ? requestAnimationFrame(this.tick) : 0;
  };

  kick() {
    if (!this.raf) {
      this.last = 0;
      this.raf = requestAnimationFrame(this.tick);
    }
  }

  stop() {
    cancelAnimationFrame(this.raf);
    this.raf = 0;
  }
}

/** Reads where each character of `text` sits, from the hidden measure row. */
function measureTokens(measure: HTMLElement, text: string) {
  const chars = splitGraphemes(text);
  const cells = measure.children;
  const tokens: Token[] = [];
  chars.forEach((char, i) => {
    const cell = cells[i] as HTMLElement | undefined;
    if (!cell || isBlank(char)) {
      return;
    }
    tokens.push({ char, x: cell.offsetLeft, digit: isDigit(char), slot: 0 });
  });
  let slot = 0;
  for (let i = tokens.length - 1; i >= 0; i--) {
    const t = tokens[i];
    if (t?.digit) {
      t.slot = slot++;
    }
  }
  return { tokens, width: measure.offsetWidth };
}

function MorphLayer({
  text,
  reducedRef,
}: {
  text: string;
  reducedRef: RefObject<boolean>;
}) {
  const chars = splitGraphemes(text);
  const rootRef = useRef<HTMLSpanElement>(null);
  const measureRef = useRef<HTMLSpanElement>(null);
  const engineRef = useRef<MorphEngine | null>(null);
  if (!engineRef.current) {
    engineRef.current = new MorphEngine();
  }
  const engine = engineRef.current;
  // Server and first client render lay the text out in flow; after mount the
  // glyphs switch to absolutely positioned, physics-driven spans.
  const [live, setLive] = useState(false);
  const [views, setViews] = useState<GlyphView[]>([]);

  useLayoutEffect(() => {
    engine.root = rootRef.current;
    engine.onChange = () => setViews(engine.views());
    setLive(true);
    return () => engine.stop();
  }, [engine]);

  useLayoutEffect(() => {
    const root = rootRef.current;
    const measure = measureRef.current;
    if (!(live && root && measure)) {
      return;
    }
    engine.em = Number.parseFloat(getComputedStyle(root).fontSize) || 16;
    engine.reduced = reducedRef.current;
    const { tokens, width } = measureTokens(measure, text);
    engine.update(tokens, width);
    setViews(engine.views());
    engine.kick();
  }, [engine, live, text, reducedRef]);

  // Fonts loading or the font size changing move the letters: re-place them.
  useEffect(() => {
    const root = rootRef.current;
    const measure = measureRef.current;
    if (!(live && root && measure)) {
      return;
    }
    const observer = new ResizeObserver(() => {
      engine.em = Number.parseFloat(getComputedStyle(root).fontSize) || 16;
      const { tokens, width } = measureTokens(measure, text);
      engine.place(tokens, width);
    });
    observer.observe(measure);
    return () => observer.disconnect();
  }, [engine, live, text]);

  return (
    <span className="relative inline-block align-baseline" ref={rootRef}>
      <span
        aria-hidden="true"
        className="pointer-events-none invisible absolute top-0 left-0"
        ref={measureRef}
      >
        {chars.map((char, i) => (
          // biome-ignore lint/suspicious/noArrayIndexKey: characters are positional.
          <span key={i}>{char}</span>
        ))}
      </span>
      {live ? (
        <>
          <span aria-hidden="true" className="inline-block w-0">
            {"​"}
          </span>
          {views.map((view) => (
            <span
              aria-hidden="true"
              className="absolute top-0 left-0 origin-[50%_80%]"
              key={view.id}
              ref={engine.refFor(view.id)}
            >
              {view.char}
            </span>
          ))}
        </>
      ) : (
        <span aria-hidden="true">
          {chars.map((char, i) => (
            // biome-ignore lint/suspicious/noArrayIndexKey: characters are positional.
            <span key={i}>{char}</span>
          ))}
        </span>
      )}
    </span>
  );
}

/* Decode ---------------------------------------------------------------- */

const UPPER = "ABCDEFGHIJKLMNOPQRSTUVWXYZ#%&*+=<>/";
const LOWER = "abcdefghijklmnopqrstuvwxyz#%&*+=<>/";
const DIGITS = "0123456789";
const SWAP_EVERY = 0.05;
const FLASH_FOR = 0.05;

function poolFor(char: string) {
  if (isDigit(char)) {
    return DIGITS;
  }
  return char.toLowerCase() === char ? LOWER : UPPER;
}

const randomFrom = (pool: string) =>
  pool[Math.floor(Math.random() * pool.length)] ?? "";

function writeCell(cell: Element | undefined, char: string) {
  const node = cell?.firstChild;
  if (node && node.nodeValue !== char) {
    node.nodeValue = char;
  }
}

interface DecodeCell {
  el: HTMLElement;
  char: string;
  lockAt: number;
  swapAt: number;
  state: "scramble" | "flash" | "done";
}

function stepCell(cell: DecodeCell, t: number) {
  if (cell.state === "flash") {
    if (t >= cell.lockAt + FLASH_FOR) {
      cell.el.removeAttribute("data-flash");
      cell.state = "done";
    }
    return;
  }
  if (t >= cell.lockAt) {
    writeCell(cell.el, cell.char);
    cell.el.removeAttribute("data-scramble");
    cell.el.setAttribute("data-flash", "");
    cell.state = "flash";
    return;
  }
  if (t >= cell.swapAt) {
    writeCell(cell.el, randomFrom(poolFor(cell.char)));
    cell.swapAt = t + SWAP_EVERY;
  }
}

function DecodeLayer({
  text,
  running,
  reducedRef,
}: {
  text: string;
  running: boolean;
  reducedRef: RefObject<boolean>;
}) {
  const chars = splitGraphemes(text);
  const hostRef = useRef<HTMLSpanElement>(null);
  /** What the cells settled on last time, so only changed cells scramble. */
  const shownRef = useRef<string[] | null>(null);

  useEffect(() => {
    const host = hostRef.current;
    if (!(host && running)) {
      return;
    }
    const next = splitGraphemes(text);
    const previous = shownRef.current;
    shownRef.current = next;
    const els = Array.from(host.children) as HTMLElement[];
    // A previous run may have left scrambled glyphs behind: reset to the text.
    els.forEach((el, i) => {
      writeCell(el, next[i] ?? "");
      el.removeAttribute("data-scramble");
      el.removeAttribute("data-flash");
    });
    const changed = next
      .map((char, i) => ({ char, i }))
      .filter(({ char, i }) => !isBlank(char) && previous?.[i] !== char);
    if (changed.length === 0) {
      return;
    }
    if (reducedRef.current) {
      host.animate([{ opacity: 0 }, { opacity: 1 }], {
        duration: 160,
        easing: "ease-out",
      });
      return;
    }
    const stagger = Math.min(0.05, 0.75 / changed.length);
    const cells: DecodeCell[] = [];
    changed.forEach(({ char, i }, rank) => {
      const el = els[i];
      if (el) {
        el.setAttribute("data-scramble", "");
        cells.push({
          el,
          char,
          lockAt: 0.15 + rank * stagger,
          swapAt: 0,
          state: "scramble",
        });
      }
    });
    // One rAF writes every cell: no React render per tick, no layout shift.
    let raf = 0;
    let start = 0;
    const tick = (now: number) => {
      start ||= now;
      const t = (now - start) / 1000;
      for (const cell of cells) {
        stepCell(cell, t);
      }
      raf = cells.every((c) => c.state === "done")
        ? 0
        : requestAnimationFrame(tick);
    };
    raf = requestAnimationFrame(tick);
    return () => {
      cancelAnimationFrame(raf);
      for (const cell of cells) {
        writeCell(cell.el, cell.char);
        cell.el.removeAttribute("data-scramble");
        cell.el.removeAttribute("data-flash");
      }
    };
  }, [text, running, reducedRef]);

  return (
    <span aria-hidden="true" className="font-mono" ref={hostRef}>
      {chars.map((char, i) => (
        <span
          className="inline-block w-[1ch] text-center data-flash:text-(--dynamic-text-accent) data-scramble:opacity-45"
          // biome-ignore lint/suspicious/noArrayIndexKey: cells are positional.
          key={i}
        >
          {char}
        </span>
      ))}
    </span>
  );
}

/* Component ------------------------------------------------------------- */

const DynamicText = ({
  mode = "morph",
  text,
  words,
  interval,
  loop,
  onComplete,
  className,
}: DynamicTextProps) => {
  const list = (words ?? DEFAULT_WORDS[mode]).map(toGreeting);
  const count = list.length;
  const hold = interval ?? DEFAULT_INTERVAL[mode];
  const repeat = loop ?? mode !== "cycle";
  const controlled = text !== undefined;
  const rootRef = useRef<HTMLSpanElement>(null);
  const reducedRef = useReducedMotionRef();
  const running = useRunning(rootRef);
  // Counts every advance; the shown word is derived from it.
  const [step, setStep] = useState(0);
  const index = repeat ? step % Math.max(count, 1) : Math.min(step, count - 1);
  const isLast = index === count - 1;
  const isDone = !(controlled || repeat) && isLast;
  const onCompleteRef = useRef(onComplete);

  useEffect(() => {
    onCompleteRef.current = onComplete;
  }, [onComplete]);

  useEffect(() => {
    if (controlled || isDone || !running || count < 2) {
      return;
    }
    const id = setTimeout(
      () => setStep((s) => s + 1),
      holdFor(mode, index, count, hold)
    );
    return () => clearTimeout(id);
  }, [controlled, isDone, running, count, mode, index, hold]);

  useEffect(() => {
    if (isDone) {
      onCompleteRef.current?.();
    }
  }, [isDone]);

  const current: Greeting = controlled
    ? { text }
    : (list[index] ?? { text: "" });

  return (
    <span
      className={cn(
        "inline-block whitespace-pre tabular-nums [--dynamic-text-accent:var(--color-emerald-600)] dark:[--dynamic-text-accent:var(--color-emerald-400)]",
        className
      )}
      lang={current.lang}
      ref={rootRef}
    >
      {/* Rapid cycling would flood a screen reader, so cycle stays quiet. */}
      <span aria-live={mode === "cycle" ? "off" : "polite"} className="sr-only">
        {current.text}
      </span>
      {mode === "decode" ? (
        <DecodeLayer
          reducedRef={reducedRef}
          running={running}
          text={current.text}
        />
      ) : (
        <MorphLayer reducedRef={reducedRef} text={current.text} />
      )}
    </span>
  );
};

export default DynamicText;
```


---

# Glitch Text
> Flat text that cuts into hard-shifted bands with a thin red/cyan split, on idle, hover or text change.

Source: https://kokonutui.com/docs/texts/glitch-text

## Installation

```bash
npx shadcn@latest add @kokonutui/glitch-text
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Glitch Text (Signal Text). Flat text that bursts into hard-cut
 * horizontal bands with a thin red/cyan channel split, on idle, hover, or as
 * the transition to new text.
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import type { CSSProperties, PointerEvent } from "react";
import {
  useCallback,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

/**
 * - `idle`: a burst every 4-9s while on screen, plus on text changes.
 * - `hover`: a burst on pointer enter (or tap), plus on text changes.
 * - `change`: only text changes glitch; the burst is the transition.
 */
export type GlitchTextTrigger = "idle" | "hover" | "change";

export type GlitchTextIntensity = "subtle" | "medium" | "strong";

export interface GlitchTextProps {
  /** Text to render. Changing it glitches over to the new text. */
  text?: string;
  /** What starts a burst. Defaults to `idle`. */
  trigger?: GlitchTextTrigger;
  /** Band count, displacement and channel split. Defaults to `medium`. */
  intensity?: GlitchTextIntensity;
  /** Color of the leading channel during a burst. The other one is cyan. */
  accent?: string;
  className?: string;
  /** Root element. A span by default, so it also fits inside a heading. */
  as?: "span" | "div" | "p" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6";
}

interface Settings {
  /** Horizontal bands the text is cut into. */
  bands: number;
  /** Max sideways jump of a band, in em (so it scales with the font). */
  shift: number;
  /** Max red/cyan channel offset, in px. */
  split: number;
  /** Hard-cut frames per burst. */
  frames: number;
  /** Length of one frame, in ms. */
  frame: number;
}

const INTENSITY: Record<GlitchTextIntensity, Settings> = {
  subtle: { bands: 3, shift: 0.05, split: 1, frames: 5, frame: 55 },
  medium: { bands: 4, shift: 0.12, split: 2, frames: 6, frame: 55 },
  strong: { bands: 5, shift: 0.18, split: 3, frames: 7, frame: 50 },
};

const MAX_BANDS = 5;
const BAND_IDS = Array.from({ length: MAX_BANDS }, (_, i) => `band-${i}`);
const DEFAULT_ACCENT = "oklch(0.63 0.24 25)";
const CYAN = "oklch(0.78 0.14 205)";
// Each keyframe holds until the next one: a glitch cuts, it doesn't glide.
const HOLD = "steps(1, end)";
const FIRST_IDLE = 1200;
const IDLE_MIN = 4000;
const IDLE_SPREAD = 5000;
// Chance that a band stays put on a given frame, so the cut reads as broken
// signal rather than a uniform shake.
const STILL_CHANCE = 0.3;

const round = (n: number) => Math.round(n * 1000) / 1000;

const prefersReducedMotion = () =>
  window.matchMedia("(prefers-reduced-motion: reduce)").matches;

/** Keyframes that hold each value for one frame, then end on the last one. */
const held = (frames: Keyframe[]): Keyframe[] => [
  ...frames.map((k, i) => ({ ...k, offset: i / frames.length, easing: HOLD })),
  { ...frames.at(-1), offset: 1 },
];

/** Random band boundaries from 0 to 100%, no band much thinner than another. */
const randomCuts = (count: number) => {
  const weights = Array.from({ length: count }, () => 0.55 + Math.random());
  const total = weights.reduce((a, b) => a + b, 0);
  const cuts = [0];
  for (const w of weights) {
    cuts.push(round((cuts.at(-1) ?? 0) + (w / total) * 100));
  }
  return cuts;
};

const jump = (max: number) => {
  if (Math.random() < STILL_CHANCE) {
    return 0;
  }
  const sign = Math.random() < 0.5 ? -1 : 1;
  return round(sign * (0.25 + 0.75 * Math.random()) * max);
};

/** Sideways positions of one band: off on frame one, home on the last. */
const bandPath = (s: Settings, forceMove: boolean) =>
  Array.from({ length: s.frames }, (_, f) => {
    if (f === s.frames - 1) {
      return 0;
    }
    const x = jump(s.shift);
    return f === 0 && forceMove && x === 0 ? round(s.shift * 0.6) : x;
  });

interface Shown {
  /** Text the bands show first during a change burst. */
  from: string | null;
  to: string;
  /** Bumped on every text change. */
  id: number;
}

const LAYER = "col-start-1 row-start-1 grid";
const TEXT = "col-start-1 row-start-1";
const GHOST = "pointer-events-none select-none opacity-0";

function LayerText({ from, to }: { from: string | null; to: string }) {
  return (
    <>
      {from !== null && (
        <span className={cn(TEXT, "opacity-0")} data-text="from">
          {from}
        </span>
      )}
      <span className={TEXT} data-text="to">
        {to}
      </span>
    </>
  );
}

const GlitchText = ({
  text = "Signal Text",
  trigger = "idle",
  intensity = "medium",
  accent = DEFAULT_ACCENT,
  className,
  as: Root = "span",
}: GlitchTextProps) => {
  const layersRef = useRef<HTMLSpanElement>(null);
  const animsRef = useRef<Animation[]>([]);
  const runningRef = useRef(false);
  const intensityRef = useRef(intensity);
  intensityRef.current = intensity;

  const [shown, setShown] = useState<Shown>({ from: null, to: text, id: 0 });
  if (shown.to !== text) {
    setShown({ from: shown.to, to: text, id: shown.id + 1 });
  }

  const stop = useCallback(() => {
    for (const a of animsRef.current) {
      a.cancel();
    }
    animsRef.current = [];
    runningRef.current = false;
  }, []);

  /** Runs one burst. With `swap`, the bands cut from old text to new midway. */
  const burst = useCallback(
    (swap: boolean, onDone?: () => void) => {
      const root = layersRef.current;
      if (!root) {
        return;
      }
      stop();
      const s = INTENSITY[intensityRef.current];
      const opts: KeyframeAnimationOptions = {
        duration: s.frames * s.frame,
        fill: "none",
      };
      const anims: Animation[] = [];
      const run = (el: Element, frames: Keyframe[]) => {
        anims.push(el.animate(held(frames), opts));
      };

      const base = root.querySelector('[data-layer="base"]');
      if (base) {
        run(base, [{ opacity: 0 }]);
      }

      // The bands tile the text top to bottom, so at rest they rebuild it.
      // The outer edges reach past the box to keep ascenders and descenders.
      const cuts = randomCuts(s.bands);
      const bands = root.querySelectorAll<HTMLElement>('[data-layer="band"]');
      const mover = Math.floor(Math.random() * s.bands);
      bands.forEach((band, i) => {
        if (i >= s.bands) {
          return;
        }
        const top = i === 0 ? -50 : cuts[i];
        const bottom = i === s.bands - 1 ? -50 : round(100 - cuts[i + 1]);
        band.style.clipPath = `inset(${top}% -25% ${bottom}% -25%)`;
        run(
          band,
          bandPath(s, i === mover).map((x) => ({
            opacity: 1,
            transform: `translate3d(${x}em, 0, 0)`,
          }))
        );
      });

      // Red and cyan copies sit behind the bands and peek out on either side.
      const channels = root.querySelectorAll('[data-layer="channel"]');
      const offsets = Array.from({ length: s.frames }, () =>
        Math.max(1, Math.ceil(Math.random() * s.split))
      );
      channels.forEach((channel, c) => {
        const dir = c === 0 ? -1 : 1;
        run(
          channel,
          offsets.map((d, f) => ({
            opacity: f === s.frames - 1 ? 0 : 1,
            transform: `translate3d(${dir * d}px, 0, 0)`,
          }))
        );
      });

      if (swap) {
        const half = Math.ceil(s.frames / 2);
        const flip = (selector: string, before: number) => {
          for (const el of root.querySelectorAll(selector)) {
            run(
              el,
              Array.from({ length: s.frames }, (_, f) => ({
                opacity: f < half ? before : 1 - before,
              }))
            );
          }
        };
        flip('[data-layer]:not([data-layer="base"]) [data-text="from"]', 1);
        flip('[data-layer]:not([data-layer="base"]) [data-text="to"]', 0);
      }

      animsRef.current = anims;
      runningRef.current = true;
      const last = anims.at(-1);
      if (last) {
        last.onfinish = () => {
          animsRef.current = [];
          runningRef.current = false;
          onDone?.();
        };
      }
    },
    [stop]
  );

  // Text changed: the burst is the transition. A layout effect, so the new
  // text never paints clean before the bands take over.
  useLayoutEffect(() => {
    if (shown.from === null) {
      return;
    }
    const id = shown.id;
    const settle = () =>
      setShown((s) => (s.id === id ? { ...s, from: null } : s));
    if (prefersReducedMotion()) {
      settle();
      return;
    }
    burst(true, settle);
  }, [shown.from, shown.id, burst]);

  // Idle: a rare burst every 4-9s, only while on screen and the tab is visible.
  useEffect(() => {
    const root = layersRef.current;
    if (trigger !== "idle" || !root) {
      return;
    }
    let visible = false;
    let timer: ReturnType<typeof setTimeout> | undefined;
    const schedule = (delay: number) => {
      clearTimeout(timer);
      timer = setTimeout(() => {
        if (
          !(document.hidden || runningRef.current || prefersReducedMotion())
        ) {
          burst(false);
        }
        schedule(IDLE_MIN + Math.random() * IDLE_SPREAD);
      }, delay);
    };
    const update = () => {
      if (visible && !document.hidden) {
        if (timer === undefined) {
          schedule(FIRST_IDLE);
        }
      } else {
        clearTimeout(timer);
        timer = undefined;
      }
    };
    const io = new IntersectionObserver(([entry]) => {
      visible = entry?.isIntersecting ?? false;
      update();
    });
    io.observe(root);
    document.addEventListener("visibilitychange", update);
    return () => {
      io.disconnect();
      document.removeEventListener("visibilitychange", update);
      clearTimeout(timer);
    };
  }, [trigger, burst]);

  useEffect(() => stop, [stop]);

  const onPointer = (e: PointerEvent) => {
    // Mouse bursts on enter; touch and pen burst on press, since they can't hover.
    const isMouse = e.pointerType === "mouse";
    if (
      trigger !== "hover" ||
      (e.type === "pointerenter") !== isMouse ||
      runningRef.current ||
      prefersReducedMotion()
    ) {
      return;
    }
    burst(false);
  };

  const { from, to } = shown;

  return (
    <Root
      className={cn(
        "relative inline-block text-zinc-900 dark:text-zinc-100",
        className
      )}
      onPointerDown={onPointer}
      onPointerEnter={onPointer}
      style={{ "--glitch-accent": accent } as CSSProperties}
    >
      <span className="sr-only">{text}</span>
      <span aria-hidden="true" className="relative inline-grid" ref={layersRef}>
        <span
          className={cn(LAYER, GHOST)}
          data-layer="channel"
          style={{ color: "var(--glitch-accent)" }}
        >
          <LayerText from={from} to={to} />
        </span>
        <span
          className={cn(LAYER, GHOST)}
          data-layer="channel"
          style={{ color: CYAN }}
        >
          <LayerText from={from} to={to} />
        </span>
        <span className={LAYER} data-layer="base">
          <LayerText from={from} to={to} />
        </span>
        {BAND_IDS.map((id) => (
          <span className={cn(LAYER, GHOST)} data-layer="band" key={id}>
            <LayerText from={from} to={to} />
          </span>
        ))}
      </span>
    </Root>
  );
};

export default GlitchText;
```


---

# Plucked Text
> A headline sitting on a string you can pluck, strum and let ring, built with React and real string physics.

Source: https://kokonutui.com/docs/texts/plucked-text

## Installation

```bash
npx shadcn@latest add @kokonutui/plucked-text
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Plucked Text
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

export interface PluckedTextProps {
  /** The line of text that sits on the string. Keep it to one line. */
  text?: string;
  className?: string;
  /** How taut the string is. Higher rings faster and settles sooner. */
  tension?: number;
  /** Strum the string when the cursor sweeps across it, not only on drag. */
  strum?: boolean;
}

// The string is simulated as a sum of its standing waves (modes), each one a
// damped oscillator solved exactly, so it can't blow up at any frame rate.
const MAX_MODES = 24;
// No mode may vibrate faster than this many times a second; above it, a
// 60 Hz screen would alias it into jitter.
const MAX_MODE_HZ = 22;
// Wave speed along the string, in px per second, at tension 1. A real
// string keeps its wave speed, so a longer one rings lower.
const WAVE_SPEED = 1500;
// Damping: every mode loses some energy, high ones much faster, so a pluck
// starts sharp and rounds off into a slow sway, as a real string does.
const DAMP_BASE = 0.9;
const DAMP_HIGH = 0.012;
// Sample spacing along the string for the drawn path, in px.
const STEP = 6;
// Displacements flatten out past this fraction of the font size, so a
// hard pull bends the line without throwing letters off it.
const MAX_SWING = 0.6;
// How much of a sweep's vertical speed reaches the string.
const STRUM_GAIN = 0.55;
const MAX_STRUM_SPEED = 2400;
// Below this energy the string is at rest and the loop stops.
const REST_ENERGY = 0.02;
// Letters tilt with the string, a little less than its full slope.
const TILT = 0.85;

interface Mode {
  q: number;
  v: number;
  omega: number;
  gamma: number;
  damped: number;
}

/** Advance one damped oscillator by `dt` seconds, exactly. */
function stepMode(mode: Mode, dt: number) {
  const { q, v, omega, gamma, damped } = mode;
  const decay = Math.exp(-gamma * dt);
  const c = Math.cos(damped * dt);
  const s = Math.sin(damped * dt);
  mode.q = decay * (q * c + ((v + gamma * q) / damped) * s);
  mode.v = decay * (v * c - ((omega * omega * q + gamma * v) / damped) * s);
}

/**
 * The string pulled into a V with its apex at `apex` and height `height`,
 * written as standing waves. Cutting the series short rounds the corner.
 */
function triangleModes(
  modes: Mode[],
  length: number,
  apex: number,
  height: number
) {
  const d = Math.min(Math.max(apex, 1), length - 1);
  modes.forEach((mode, index) => {
    const n = index + 1;
    mode.q =
      ((2 * height * length * length) /
        (n * n * Math.PI * Math.PI * d * (length - d))) *
      Math.sin((n * Math.PI * d) / length);
    mode.v = 0;
  });
}

/** Rubber band: grows like `x` near zero and never past `max`. */
function soften(x: number, max: number) {
  return max * Math.tanh(x / max);
}

export default function PluckedText({
  text = "Good vibrations",
  className,
  tension = 1,
  strum = true,
}: PluckedTextProps) {
  const stageRef = useRef<HTMLDivElement>(null);
  const lettersRef = useRef<HTMLSpanElement>(null);
  const svgRef = useRef<SVGSVGElement>(null);
  const pathRef = useRef<SVGPathElement>(null);
  const ghostRef = useRef<SVGPathElement>(null);

  useEffect(() => {
    const stage = stageRef.current;
    const lettersEl = lettersRef.current;
    const svg = svgRef.current;
    const path = pathRef.current;
    const ghost = ghostRef.current;
    if (!(stage && lettersEl && svg && path && ghost)) {
      return;
    }

    const reduceMotion = window.matchMedia(
      "(prefers-reduced-motion: reduce)"
    ).matches;
    const letters = Array.from(lettersEl.children).slice(
      0,
      -1
    ) as HTMLElement[];

    let length = 0;
    let swing = 0;
    let modes: Mode[] = [];
    // Precomputed sin and cos of every mode at every sample and letter.
    let pathBasis: Float64Array[] = [];
    let letterBasis: { sin: Float64Array; cos: Float64Array }[] = [];
    let raf = 0;
    let last = 0;
    let visible = true;
    let lastPath = "";

    // Pointer state: a grab holds the string in a V; otherwise the last
    // position is kept to notice the cursor sweeping across the line.
    let grab: { id: number; x: number; y: number } | null = null;
    let release: { from: Float64Array; start: number } | null = null;
    let prev: { x: number; y: number; t: number } | null = null;

    const measure = () => {
      // The string sits on the text's baseline, found with an empty
      // inline-block, whose bottom edge rests on it.
      const probe = lettersEl.lastElementChild as HTMLElement;
      stage.style.setProperty(
        "--pluck-baseline",
        `${lettersEl.offsetTop + probe.offsetTop + probe.offsetHeight}px`
      );
      const svgBox = svg.getBoundingClientRect();
      const lettersLeft = lettersEl.getBoundingClientRect().left - svgBox.left;
      length = svgBox.width;
      swing = Number.parseFloat(getComputedStyle(stage).fontSize) * MAX_SWING;
      const f0 = (WAVE_SPEED * tension) / (2 * length);
      const count = Math.max(
        4,
        Math.min(MAX_MODES, Math.floor(MAX_MODE_HZ / f0))
      );
      const old = modes;
      modes = Array.from({ length: count }, (_, index) => {
        const n = index + 1;
        const omega = 2 * Math.PI * f0 * n;
        const gamma = (DAMP_BASE + DAMP_HIGH * n * n) * Math.sqrt(tension);
        return {
          q: old[index]?.q ?? 0,
          v: old[index]?.v ?? 0,
          omega,
          gamma,
          damped: Math.sqrt(Math.max(omega * omega - gamma * gamma, 1)),
        };
      });
      const samples = Math.ceil(length / STEP) + 1;
      pathBasis = Array.from({ length: samples }, (_, i) => {
        const x = Math.min(i * STEP, length);
        return Float64Array.from(modes, (_m, index) =>
          Math.sin(((index + 1) * Math.PI * x) / length)
        );
      });
      letterBasis = letters.map((letter) => {
        // Offsets ignore the transform the loop applies.
        const x = lettersLeft + letter.offsetLeft + letter.offsetWidth / 2;
        const k = (index: number) => ((index + 1) * Math.PI) / length;
        return {
          sin: Float64Array.from(modes, (_m, index) => Math.sin(k(index) * x)),
          cos: Float64Array.from(
            modes,
            (_m, index) => k(index) * Math.cos(k(index) * x)
          ),
        };
      });
    };

    /** Displacement of the string where `basis` was sampled. */
    const sum = (basis: Float64Array) => {
      let y = 0;
      for (let i = 0; i < modes.length; i++) {
        y += modes[i].q * basis[i];
      }
      return y;
    };

    const draw = () => {
      let d = "";
      for (let i = 0; i < pathBasis.length; i++) {
        const x = Math.min(i * STEP, length);
        const y = soften(sum(pathBasis[i]), swing);
        d += `${i === 0 ? "M" : "L"}${x.toFixed(1)} ${y.toFixed(2)}`;
      }
      // The previous frame stays behind faintly: a vibrating string blurs.
      ghost.setAttribute("d", lastPath || d);
      path.setAttribute("d", d);
      lastPath = d;
      for (let i = 0; i < letters.length; i++) {
        const { sin, cos } = letterBasis[i];
        const raw = sum(sin);
        const y = soften(raw, swing);
        // Slope of the softened curve, so tilt eases off with the swing.
        const t = Math.tanh(raw / swing);
        const slope = sum(cos) * (1 - t * t);
        const angle = Math.atan(slope) * TILT;
        letters[i].style.transform =
          `translate3d(0, ${y.toFixed(2)}px, 0) rotate(${angle.toFixed(4)}rad)`;
      }
    };

    const energy = () =>
      modes.reduce((e, m) => e + m.v * m.v + m.omega * m.omega * m.q * m.q, 0);

    const settle = () => {
      for (const mode of modes) {
        mode.q = 0;
        mode.v = 0;
      }
    };

    /** Reduced motion: no ringing, the line just eases back flat. */
    const easeBack = (now: number) => {
      if (!release) {
        return;
      }
      const t = Math.min((now - release.start) / 260, 1);
      const left = (1 - t) ** 3;
      const from = release.from;
      modes.forEach((mode, index) => {
        mode.q = from[index] * left;
      });
      if (t >= 1) {
        release = null;
        settle();
      }
    };

    const advance = (now: number, dt: number) => {
      if (release) {
        easeBack(now);
      } else if (!grab) {
        for (const mode of modes) {
          stepMode(mode, dt);
        }
      }
    };

    const frame = (now: number) => {
      raf = 0;
      if (!visible) {
        return;
      }
      const dt = last ? Math.min((now - last) / 1000, 1 / 30) : 1 / 60;
      last = now;
      advance(now, dt);
      draw();
      if (grab || release || energy() > REST_ENERGY) {
        raf = requestAnimationFrame(frame);
        return;
      }
      settle();
      draw();
      ghost.setAttribute("d", path.getAttribute("d") ?? "");
    };

    const start = () => {
      if (!raf && visible) {
        last = 0;
        raf = requestAnimationFrame(frame);
      }
    };

    /** Pointer position along the string and above or below it. */
    const local = (event: PointerEvent) => {
      const r = svg.getBoundingClientRect();
      return { x: event.clientX - r.left, y: event.clientY - r.top };
    };

    const lineAt = (x: number) => {
      let y = 0;
      for (let i = 0; i < modes.length; i++) {
        y += modes[i].q * Math.sin(((i + 1) * Math.PI * x) / length);
      }
      return soften(y, swing);
    };

    const onDown = (event: PointerEvent) => {
      if (grab || event.button !== 0) {
        return;
      }
      const point = local(event);
      if (point.x < 0 || point.x > length) {
        return;
      }
      event.preventDefault();
      stage.setPointerCapture(event.pointerId);
      release = null;
      grab = { id: event.pointerId, x: point.x, y: point.y };
      stage.dataset.grabbing = "";
      triangleModes(modes, length, point.x, lineAt(point.x));
      start();
    };

    const onMove = (event: PointerEvent) => {
      const point = local(event);
      if (grab && event.pointerId === grab.id) {
        // Follow the hand along the string, and up or down with a pull
        // that stiffens the further it goes.
        grab.x = Math.min(Math.max(point.x, 0), length);
        grab.y = soften(point.y, swing * 1.6);
        triangleModes(modes, length, grab.x, grab.y);
        start();
        return;
      }
      if (!(strum && event.pointerType === "mouse") || reduceMotion) {
        prev = null;
        return;
      }
      const now = event.timeStamp;
      if (prev && point.x >= 0 && point.x <= length) {
        // Did the cursor cross the line since the last move? Then it
        // strums it there, as hard as it was moving.
        const before = prev.y - lineAt(prev.x);
        const after = point.y - lineAt(point.x);
        if (before * after < 0) {
          const dt = Math.max(now - prev.t, 8) / 1000;
          const speed = Math.max(
            -MAX_STRUM_SPEED,
            Math.min(MAX_STRUM_SPEED, (point.y - prev.y) / dt)
          );
          const where =
            prev.x + (point.x - prev.x) * (before / (before - after));
          modes.forEach((mode, index) => {
            const n = index + 1;
            mode.v +=
              ((STRUM_GAIN * speed * 80) / length) *
              Math.sin((n * Math.PI * where) / length) *
              Math.exp(-((n / 14) ** 2));
          });
          start();
        }
      }
      prev = { x: point.x, y: point.y, t: now };
    };

    const onUp = (event: PointerEvent) => {
      if (!grab || event.pointerId !== grab.id) {
        return;
      }
      grab = null;
      delete stage.dataset.grabbing;
      if (reduceMotion) {
        release = {
          from: Float64Array.from(modes, (mode) => mode.q),
          start: performance.now(),
        };
      }
      start();
    };

    const onLeave = () => {
      prev = null;
    };

    measure();
    draw();

    const resizeObserver = new ResizeObserver(() => {
      measure();
      draw();
    });
    resizeObserver.observe(stage);
    // Letter widths change when a web font arrives.
    document.fonts?.ready.then(() => {
      measure();
      draw();
    });

    // One soft strum the first time the line scrolls into view, so it
    // shows it can move.
    let greeted = reduceMotion;
    const intersection = new IntersectionObserver(
      ([entry]) => {
        visible =
          entry.isIntersecting && document.visibilityState === "visible";
        if (!visible) {
          return;
        }
        if (!greeted && entry.intersectionRatio > 0.6) {
          greeted = true;
          triangleModes(modes, length, length * 0.3, -swing * 0.5);
        }
        start();
      },
      { threshold: [0, 0.6] }
    );
    intersection.observe(stage);
    const onVisibility = () => {
      visible = document.visibilityState === "visible";
      if (visible) {
        start();
      }
    };
    document.addEventListener("visibilitychange", onVisibility);

    stage.addEventListener("pointerdown", onDown);
    stage.addEventListener("pointermove", onMove);
    stage.addEventListener("pointerup", onUp);
    stage.addEventListener("pointercancel", onUp);
    stage.addEventListener("pointerleave", onLeave);

    return () => {
      cancelAnimationFrame(raf);
      resizeObserver.disconnect();
      intersection.disconnect();
      document.removeEventListener("visibilitychange", onVisibility);
      stage.removeEventListener("pointerdown", onDown);
      stage.removeEventListener("pointermove", onMove);
      stage.removeEventListener("pointerup", onUp);
      stage.removeEventListener("pointercancel", onUp);
      stage.removeEventListener("pointerleave", onLeave);
    };
  }, [tension, strum]);

  return (
    <div className={cn("@container flex w-full justify-center", className)}>
      <div
        className="group/pluck relative cursor-grab touch-none select-none px-[0.5em] py-[0.7em] font-semibold text-[clamp(2rem,11cqi,6rem)] text-zinc-900 leading-none tracking-tight data-[grabbing]:cursor-grabbing dark:text-zinc-100"
        ref={stageRef}
      >
        <span className="sr-only">{text}</span>
        <span
          aria-hidden="true"
          className="relative block whitespace-pre"
          ref={lettersRef}
        >
          {Array.from(text).map((char, index) => (
            <span
              className="inline-block origin-[50%_100%] will-change-transform"
              // biome-ignore lint/suspicious/noArrayIndexKey: letters repeat; their position is their identity.
              key={index}
            >
              {char}
            </span>
          ))}
          <span className="inline-block h-0 w-0" />
        </span>
        {/* The string runs along the baseline, pinned at both ends. */}
        <svg
          aria-hidden="true"
          className="pointer-events-none absolute left-[0.25em] h-px w-[calc(100%-0.5em)] overflow-visible text-zinc-400 dark:text-zinc-600"
          ref={svgRef}
          style={{ top: "var(--pluck-baseline, 1.56em)" }}
        >
          <path
            className="opacity-30"
            fill="none"
            ref={ghostRef}
            stroke="currentColor"
            strokeLinecap="round"
            strokeWidth={1.5}
          />
          <path
            fill="none"
            ref={pathRef}
            stroke="currentColor"
            strokeLinecap="round"
            strokeWidth={1.5}
          />
        </svg>
        <span
          aria-hidden="true"
          className="pointer-events-none absolute left-[0.25em] size-[0.12em] -translate-x-1/2 -translate-y-1/2 rounded-full bg-zinc-400 dark:bg-zinc-600"
          style={{ top: "var(--pluck-baseline, 1.56em)" }}
        />
        <span
          aria-hidden="true"
          className="pointer-events-none absolute right-[0.25em] size-[0.12em] translate-x-1/2 -translate-y-1/2 rounded-full bg-zinc-400 dark:bg-zinc-600"
          style={{ top: "var(--pluck-baseline, 1.56em)" }}
        />
      </div>
    </div>
  );
}
```


---

# Extruded Text
> Zinc 3D extruded text lit by your pointer, with letters that press in like keycaps.

Source: https://kokonutui.com/docs/texts/swoosh-text

## Installation

```bash
npx shadcn@latest add @kokonutui/swoosh-text
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Extruded Text
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { type HTMLAttributes, type RefObject, useEffect, useRef } from "react";
import { cn } from "@/lib/utils";

interface SwooshTextProps
  extends Omit<HTMLAttributes<HTMLElement>, "children"> {
  text?: string;
  /** Element to render, e.g. "h1" for a heading. */
  as?: "div" | "span" | "p" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6";
  /** Stacked layers behind each letter (clamped to 6-16). */
  depth?: number;
  /** Total extrusion length, in em. */
  length?: number;
  /** Optional color for the deepest layer only, e.g. "#f97316". */
  accent?: string;
}

// Spring for the light direction. Under-damped on purpose: a fast flick
// swings the extrusion past its target before it settles.
const LIGHT_STIFFNESS = 170;
const LIGHT_DAMPING = 13;
// How much of the pointer's velocity is carried into the spring.
const LIGHT_KICK = 9;
const LIGHT_MAX_SPEED = 30;
const LIGHT_MAX_LENGTH = 1.35;
// Spring for each keycap, close to critical so letters sink without wobble.
const KEY_STIFFNESS = 420;
const KEY_DAMPING = 34;
// How far a fully pressed key sinks into its extrusion (fraction of depth).
const MAX_SINK = 0.72;
// Falloff radius of the press wave, in multiples of the font size.
const PRESS_RADIUS = 0.75;
// Rest: light from the top-left, extrusion toward the bottom-right (45°).
const REST = Math.SQRT1_2;
const EPSILON = 0.0008;
const WHITESPACE = /\s+/;

const segmenter =
  typeof Intl !== "undefined" && "Segmenter" in Intl
    ? new Intl.Segmenter(undefined, { granularity: "grapheme" })
    : null;

/** Splits into user-perceived characters, so emoji and accents stay whole. */
function splitGraphemes(value: string): string[] {
  return segmenter
    ? Array.from(segmenter.segment(value), (s) => s.segment)
    : Array.from(value);
}

interface Key {
  x: number;
  y: number;
  p: number;
  v: number;
  // Layers deepest first, then the face (index 0) last.
  layers: HTMLSpanElement[];
  // Last value written, so unchanged keys are skipped.
  drawn: string;
}

interface Sim {
  lx: number;
  ly: number;
  vx: number;
  vy: number;
  tx: number;
  ty: number;
  // Pointer in client coordinates, or null when it is away.
  px: number | null;
  py: number | null;
  pressed: number;
  fontSize: number;
  depth: number;
  step: number;
  keys: Key[];
}

function round(value: number) {
  return Math.round(value * 10_000) / 10_000;
}

function clamp(value: number, max: number) {
  return Math.max(-max, Math.min(max, value));
}

function lightTarget(sim: Sim, rect: DOMRect): [number, number] {
  if (sim.px === null || sim.py === null) {
    return [REST, REST];
  }
  // The extrusion points away from the light (the pointer). Near the centre
  // the light is overhead, so the extrusion shortens instead of flipping.
  const dx = rect.left + rect.width / 2 - sim.px;
  const dy = rect.top + rect.height / 2 - sim.py;
  const reach = Math.max(Math.hypot(dx, dy), sim.fontSize * 0.9);
  return [dx / reach, dy / reach];
}

function stepLight(sim: Sim, dt: number) {
  sim.vx += ((sim.tx - sim.lx) * LIGHT_STIFFNESS - sim.vx * LIGHT_DAMPING) * dt;
  sim.vy += ((sim.ty - sim.ly) * LIGHT_STIFFNESS - sim.vy * LIGHT_DAMPING) * dt;
  sim.lx += sim.vx * dt;
  sim.ly += sim.vy * dt;
  // Keep a wild flick from stretching the extrusion too far.
  const length = Math.hypot(sim.lx, sim.ly);
  if (length > LIGHT_MAX_LENGTH) {
    sim.lx = (sim.lx / length) * LIGHT_MAX_LENGTH;
    sim.ly = (sim.ly / length) * LIGHT_MAX_LENGTH;
  }
  const moving =
    Math.abs(sim.tx - sim.lx) > EPSILON ||
    Math.abs(sim.ty - sim.ly) > EPSILON ||
    Math.hypot(sim.vx, sim.vy) > EPSILON;
  if (!moving) {
    sim.lx = sim.tx;
    sim.ly = sim.ty;
    sim.vx = 0;
    sim.vy = 0;
  }
  return moving;
}

function keyTarget(sim: Sim, index: number, dx: number, dy: number) {
  if (index === sim.pressed) {
    return 1;
  }
  if (sim.px === null) {
    return 0;
  }
  const distance = Math.hypot(dx, dy) / (sim.fontSize * PRESS_RADIUS);
  return distance > 2.5 ? 0 : Math.exp(-distance * distance);
}

function stepKeys(sim: Sim, dt: number, rect: DOMRect) {
  let moving = false;
  const x = (sim.px ?? 0) - rect.left;
  const y = (sim.py ?? 0) - rect.top;
  for (let i = 0; i < sim.keys.length; i++) {
    const key = sim.keys[i];
    const target = keyTarget(sim, i, x - key.x, y - key.y) * MAX_SINK;
    key.v += ((target - key.p) * KEY_STIFFNESS - key.v * KEY_DAMPING) * dt;
    key.p += key.v * dt;
    if (Math.abs(target - key.p) < EPSILON && Math.abs(key.v) < EPSILON) {
      key.p = target;
      key.v = 0;
    } else {
      moving = true;
    }
  }
  return moving;
}

// Layer `index` sits `index` steps deep. As the key sinks (p → 1) the
// column compresses toward the deepest layer, which never moves.
function layerTransform(
  index: number,
  depth: number,
  step: number,
  light: [number, number],
  p: number
) {
  const offset = (index + (depth - index) * p) * step;
  return `translate3d(${round(light[0] * offset)}em, ${round(light[1] * offset)}em, 0)`;
}

// Writes transforms straight onto each layer. Changing a custom property on
// the root instead would restyle every descendant each frame (~10x slower).
function drawKeys(sim: Sim) {
  const light: [number, number] = [round(sim.lx), round(sim.ly)];
  for (const key of sim.keys) {
    const p = round(Math.max(0, key.p));
    const signature = `${light[0]},${light[1]},${p}`;
    if (signature === key.drawn) {
      continue;
    }
    key.drawn = signature;
    const count = key.layers.length;
    for (let j = 0; j < count; j++) {
      key.layers[j].style.transform = layerTransform(
        count - 1 - j,
        sim.depth,
        sim.step,
        light,
        p
      );
    }
  }
}

const REST_LIGHT: [number, number] = [REST, REST];

function layerColor(index: number, depth: number, accent?: string) {
  if (index === depth && accent) {
    return accent;
  }
  const t = Math.round(((index - 1) / Math.max(1, depth - 1)) * 100);
  return `color-mix(in oklab, var(--ex-far) ${t}%, var(--ex-near))`;
}

function Letter({
  char,
  depth,
  step,
  accent,
}: {
  char: string;
  depth: number;
  step: number;
  accent?: string;
}) {
  // Deepest layer first so the face paints on top.
  const layers = Array.from({ length: depth }, (_, i) => depth - i);
  return (
    <span className="relative inline-block" data-key="">
      {layers.map((i) => (
        <span
          className="absolute inset-0"
          key={i}
          style={{
            color: layerColor(i, depth, accent),
            transform: layerTransform(i, depth, step, REST_LIGHT, 0),
          }}
        >
          {char}
        </span>
      ))}
      <span
        className="relative inline-block text-[var(--ex-face)]"
        style={{ transform: layerTransform(0, depth, step, REST_LIGHT, 0) }}
      >
        {char}
      </span>
    </span>
  );
}

function measureKeys(root: HTMLElement, sim: Sim) {
  const rect = root.getBoundingClientRect();
  sim.fontSize = Number.parseFloat(getComputedStyle(root).fontSize) || 16;
  const els = root.querySelectorAll<HTMLSpanElement>("[data-key]");
  sim.keys = Array.from(els, (el, i) => {
    const r = el.getBoundingClientRect();
    const previous = sim.keys[i];
    return {
      layers: Array.from(el.children) as HTMLSpanElement[],
      drawn: "",
      x: r.left - rect.left + r.width / 2,
      y: r.top - rect.top + r.height / 2,
      p: previous?.p ?? 0,
      v: previous?.v ?? 0,
    };
  });
}

function nearestKey(sim: Sim, x: number, y: number) {
  let best = -1;
  let bestDistance = sim.fontSize * 0.8;
  for (let i = 0; i < sim.keys.length; i++) {
    const d = Math.hypot(sim.keys[i].x - x, sim.keys[i].y - y);
    if (d < bestDistance) {
      best = i;
      bestDistance = d;
    }
  }
  return best;
}

function createSim(depth: number, step: number): Sim {
  return {
    lx: REST,
    ly: REST,
    vx: 0,
    vy: 0,
    tx: REST,
    ty: REST,
    px: null,
    py: null,
    pressed: -1,
    fontSize: 16,
    depth,
    step,
    keys: [],
  };
}

function useExtrusion(
  rootRef: RefObject<HTMLElement | null>,
  text: string,
  depth: number,
  step: number
) {
  useEffect(() => {
    const root = rootRef.current;
    // `text` is read so the effect re-runs (and re-measures) when it changes.
    if (!root || text === "") {
      return;
    }
    // Reduced motion keeps the fixed 45° extrusion from the first render.
    if (window.matchMedia("(prefers-reduced-motion: reduce)").matches) {
      return;
    }

    const sim = createSim(depth, step);
    let frame = 0;
    let last = 0;
    let visible = true;
    let onScreen = true;

    const tick = (now: number) => {
      frame = 0;
      const dt = last ? Math.min((now - last) / 1000, 1 / 30) : 1 / 60;
      last = now;
      const rect = root.getBoundingClientRect();
      [sim.tx, sim.ty] = lightTarget(sim, rect);
      const lightMoving = stepLight(sim, dt);
      const keysMoving = stepKeys(sim, dt, rect);
      drawKeys(sim);
      // Sleep once everything has settled, or while offscreen.
      if ((lightMoving || keysMoving) && visible) {
        frame = requestAnimationFrame(tick);
      } else {
        last = 0;
      }
    };

    const wake = () => {
      if (!frame && visible) {
        frame = requestAnimationFrame(tick);
      }
    };

    const onMove = (event: PointerEvent) => {
      if (!visible) {
        return;
      }
      const rect = root.getBoundingClientRect();
      const [ax, ay] = lightTarget(sim, rect);
      sim.px = event.clientX;
      sim.py = event.clientY;
      const [bx, by] = lightTarget(sim, rect);
      // Carry the pointer's velocity into the spring so a flick swings it.
      sim.vx = clamp(sim.vx + (bx - ax) * LIGHT_KICK, LIGHT_MAX_SPEED);
      sim.vy = clamp(sim.vy + (by - ay) * LIGHT_KICK, LIGHT_MAX_SPEED);
      wake();
    };

    const onLeave = () => {
      sim.px = null;
      sim.py = null;
      sim.pressed = -1;
      wake();
    };

    const onDown = (event: PointerEvent) => {
      const rect = root.getBoundingClientRect();
      sim.pressed = nearestKey(
        sim,
        event.clientX - rect.left,
        event.clientY - rect.top
      );
      sim.px = event.clientX;
      sim.py = event.clientY;
      wake();
    };

    const onUp = (event: PointerEvent) => {
      sim.pressed = -1;
      // Touch has no hover: once the finger lifts, the light goes home.
      if (event.pointerType !== "mouse") {
        sim.px = null;
        sim.py = null;
      }
      wake();
    };

    const onVisibility = () => {
      visible = onScreen && !document.hidden;
      wake();
    };

    const measure = () => measureKeys(root, sim);
    measure();
    const resize = new ResizeObserver(measure);
    resize.observe(root);
    document.fonts?.ready.then(measure).catch(() => undefined);

    const intersection = new IntersectionObserver(([entry]) => {
      onScreen = entry.isIntersecting;
      visible = onScreen && !document.hidden;
      wake();
    });
    intersection.observe(root);

    window.addEventListener("pointermove", onMove, { passive: true });
    document.documentElement.addEventListener("pointerleave", onLeave);
    root.addEventListener("pointerdown", onDown);
    window.addEventListener("pointerup", onUp);
    window.addEventListener("pointercancel", onUp);
    document.addEventListener("visibilitychange", onVisibility);

    return () => {
      cancelAnimationFrame(frame);
      resize.disconnect();
      intersection.disconnect();
      window.removeEventListener("pointermove", onMove);
      document.documentElement.removeEventListener("pointerleave", onLeave);
      root.removeEventListener("pointerdown", onDown);
      window.removeEventListener("pointerup", onUp);
      window.removeEventListener("pointercancel", onUp);
      document.removeEventListener("visibilitychange", onVisibility);
    };
  }, [rootRef, text, depth, step]);
}

export default function SwooshText({
  text = "Extruded",
  as: Tag = "div",
  depth = 12,
  length = 0.2,
  accent,
  className,
  style,
  ...props
}: SwooshTextProps) {
  const rootRef = useRef<HTMLElement | null>(null);
  const layers = Math.round(Math.min(16, Math.max(6, depth)));
  const step = length / layers;
  useExtrusion(rootRef, text, layers, step);

  const words = text.split(WHITESPACE).filter(Boolean);

  return (
    <Tag
      className={cn(
        "relative touch-manipulation select-none font-bold text-5xl tracking-tight",
        "[--ex-face:var(--color-zinc-900)] [--ex-far:var(--color-zinc-600)] [--ex-near:var(--color-zinc-300)]",
        "dark:[--ex-face:var(--color-zinc-50)] dark:[--ex-far:var(--color-zinc-700)] dark:[--ex-near:var(--color-zinc-400)]",
        className
      )}
      ref={(node: HTMLElement | null) => {
        rootRef.current = node;
      }}
      style={style}
      {...props}
    >
      <span className="sr-only">{text}</span>
      <span aria-hidden="true">
        {words.map((word, w) => (
          // biome-ignore lint/suspicious/noArrayIndexKey: words can repeat
          <span key={w}>
            {w > 0 ? " " : null}
            <span className="inline-block whitespace-nowrap">
              {splitGraphemes(word).map((char, c) => (
                <Letter
                  accent={accent}
                  char={char}
                  depth={layers}
                  // biome-ignore lint/suspicious/noArrayIndexKey: letters repeat
                  key={c}
                  step={step}
                />
              ))}
            </span>
          </span>
        ))}
      </span>
    </Tag>
  );
}
```


---

# Typing Text
> Typewriter text that makes the odd typo and corrects it, erases by selecting, and blinks its caret only when idle, built with React and Motion.

Source: https://kokonutui.com/docs/texts/type-writer

## Installation

```bash
npx shadcn@latest add @kokonutui/type-writer
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Typewriter
 * @version: 1.1.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { motion, useInView, useReducedMotion } from "motion/react";
import { type Ref, useEffect, useRef, useState } from "react";
import { cn } from "@/lib/utils";

interface TypewriterSequence {
  text: string;
  deleteAfter?: boolean;
  pauseAfter?: number;
}

type TypewriterElement = "div" | "p" | "span" | "h1" | "h2" | "h3";

interface TypewriterTitleProps {
  sequences?: TypewriterSequence[];
  typingSpeed?: number;
  startDelay?: number;
  autoLoop?: boolean;
  loopDelay?: number;
  deleteSpeed?: number;
  pauseBeforeDelete?: number;
  naturalVariance?: boolean;
  /**
   * How a phrase is erased. `"backspace"` removes it one character at a
   * time; `"select"` highlights it right to left, as with Shift+Home, then
   * cuts it in one go.
   */
  deleteMode?: "backspace" | "select";
  /**
   * Hit a neighbouring key now and then, pause, backspace and correct it.
   * `true` is about a 4% chance per letter; a number sets the chance.
   */
  typos?: boolean | number;
  /** Seed for the variance and typos, so every visit types the same way. */
  seed?: number;
  /**
   * Stops the typing where it is. Wire it to a pause control to let users
   * stop the endless loop (WCAG 2.2.2). It also pauses while off screen.
   */
  paused?: boolean;
  /** Element to render, e.g. `h1` when it is the page title. */
  as?: TypewriterElement;
  /** Classes for the wrapper. Its width sets the font size. */
  className?: string;
  /** Classes for the text itself, e.g. to fix the font size. */
  textClassName?: string;
}

const DEFAULT_SEQUENCES: TypewriterSequence[] = [
  { text: "Typewriter", deleteAfter: true },
  { text: "Multiple Words", deleteAfter: true },
  { text: "Auto Loop", deleteAfter: false },
];

const NEXT_SEQUENCE_DELAY = 100;
// The caret stays solid while keys are being hit and only starts blinking
// once typing has stopped for this long, as in a text editor.
const CARET_IDLE_MS = 500;
// A wrong key: noticed after this pause, then backspaced and retyped.
const TYPO_NOTICE_MS = 250;
const DEFAULT_TYPO_RATE = 0.04;
// Select-to-delete: the highlight sweeps the phrase in this long, holds
// for a moment, then the text is cut.
const SELECT_SWEEP_MS = 120;
const SELECT_HOLD_MS = 220;

// The blink is a CSS animation so it runs off the main thread: solid for
// the first third of the cycle, fades out, then stays hidden.
const CARET_KEYFRAMES =
  "@keyframes kokonutui-typewriter-caret { 0%, 33.333% { opacity: 1; } 66.667%, 100% { opacity: 0; } }";

const KEY_ROWS = ["qwertyuiop", "asdfghjkl", "zxcvbnm"];

/** The keys around a letter on a QWERTY keyboard, in the same case. */
function neighbours(char: string) {
  const lower = char.toLowerCase();
  const row = KEY_ROWS.findIndex((keys) => keys.includes(lower));
  if (row === -1) {
    return "";
  }
  const col = KEY_ROWS[row].indexOf(lower);
  const around = [
    KEY_ROWS[row][col - 1],
    KEY_ROWS[row][col + 1],
    KEY_ROWS[row - 1]?.[col],
    KEY_ROWS[row + 1]?.[col],
  ]
    .filter(Boolean)
    .join("");
  return char === lower ? around : around.toUpperCase();
}

/** Small seeded generator (Park-Miller), 0 to 1. */
function createRandom(seed: number) {
  let state = (Math.abs(Math.floor(seed)) % 2_147_483_646) + 1;
  return () => {
    state = (state * 16_807) % 2_147_483_647;
    return (state - 1) / 2_147_483_646;
  };
}

function getTypingDelay(
  typingSpeed: number,
  naturalVariance: boolean,
  random: () => number
) {
  if (!naturalVariance) {
    return typingSpeed;
  }
  const roll = random();
  // 10% chance of a hesitation, 10% chance of a burst.
  if (roll < 0.1) {
    return typingSpeed * 2;
  }
  if (roll > 0.9) {
    return typingSpeed * 0.5;
  }
  // Otherwise +/- 40%.
  return typingSpeed * (0.6 + random() * 0.8);
}

class Stopped extends Error {}

interface Position {
  sequence: number;
  char: number;
  deleting: boolean;
}

interface Screen {
  text: string;
  /** Characters at the end of `text` shown as selected. */
  selected: number;
}

export default function TypewriterTitle({
  sequences = DEFAULT_SEQUENCES,
  typingSpeed = 50,
  startDelay = 200,
  autoLoop = true,
  loopDelay = 1000,
  deleteSpeed = 30,
  pauseBeforeDelete = 1000,
  naturalVariance = true,
  deleteMode = "backspace",
  typos = false,
  seed = 7,
  paused = false,
  as: Component = "div",
  className,
  textClassName,
}: TypewriterTitleProps) {
  const [screen, setScreen] = useState<Screen>({ text: "", selected: 0 });
  const ref = useRef<HTMLSpanElement>(null);
  const caretRef = useRef<HTMLSpanElement>(null);
  const isInView = useInView(ref);
  const isRunning = !paused && isInView;
  const shouldReduceMotion = useReducedMotion();
  const position = useRef<Position>({ sequence: 0, char: 0, deleting: false });
  const random = useRef<() => number>(createRandom(seed));

  const sequencesRef = useRef(sequences);
  useEffect(() => {
    sequencesRef.current = sequences;
  }, [sequences]);

  useEffect(() => {
    random.current = createRandom(seed);
  }, [seed]);

  // Reduced motion: show the final phrase, no typing loop. Keyed on the
  // phrase itself so new `sequences` still update the text.
  const finalText = sequences.at(-1)?.text ?? "";
  useEffect(() => {
    if (shouldReduceMotion) {
      setScreen({ text: finalText, selected: 0 });
    }
  }, [shouldReduceMotion, finalText]);

  useEffect(() => {
    if (shouldReduceMotion) {
      return;
    }
    // Paused or off screen: keep the current text. `position` remembers
    // where it was, so typing resumes there.
    if (!isRunning) {
      return;
    }

    let typoRate = 0;
    if (typeof typos === "number") {
      typoRate = typos;
    } else if (typos) {
      typoRate = DEFAULT_TYPO_RATE;
    }
    const pos = position.current;
    const timers = new Set<ReturnType<typeof setTimeout>>();
    let idleTimer: ReturnType<typeof setTimeout> | undefined;
    let stopped = false;

    const wait = (ms: number) =>
      new Promise<void>((resolve, reject) => {
        if (stopped) {
          reject(new Stopped());
          return;
        }
        const timer = setTimeout(() => {
          timers.delete(timer);
          if (stopped) {
            reject(new Stopped());
          } else {
            resolve();
          }
        }, ms);
        timers.add(timer);
      });

    // Every keystroke holds the caret solid; it blinks again once idle.
    const keystroke = () => {
      const caret = caretRef.current;
      if (!caret) {
        return;
      }
      caret.dataset.idle = "false";
      clearTimeout(idleTimer);
      idleTimer = setTimeout(() => {
        caret.dataset.idle = "true";
      }, CARET_IDLE_MS);
    };
    const show = (text: string, selected = 0) => {
      setScreen({ text, selected });
    };

    const typeChar = async (text: string) => {
      const wrongKeys = neighbours(text[pos.char]);
      if (wrongKeys && random.current() < typoRate) {
        const wrong =
          wrongKeys[Math.floor(random.current() * wrongKeys.length)];
        show(text.slice(0, pos.char) + wrong);
        keystroke();
        await wait(TYPO_NOTICE_MS + typingSpeed);
        show(text.slice(0, pos.char));
        keystroke();
        await wait(typingSpeed * 1.5);
      }
      pos.char += 1;
      show(text.slice(0, pos.char));
      keystroke();
      await wait(getTypingDelay(typingSpeed, naturalVariance, random.current));
    };

    const erase = async (text: string) => {
      if (deleteMode === "select") {
        const length = pos.char;
        const step = SELECT_SWEEP_MS / Math.max(length, 1);
        for (let selected = 1; selected <= length; selected++) {
          show(text.slice(0, length), selected);
          keystroke();
          await wait(step);
        }
        await wait(SELECT_HOLD_MS);
        pos.char = 0;
        show("");
        keystroke();
        return;
      }
      while (pos.char > 0) {
        pos.char -= 1;
        show(text.slice(0, pos.char));
        keystroke();
        await wait(deleteSpeed);
      }
    };

    /** Move on to the next phrase. False when the run is over. */
    const advance = async (delay: number) => {
      const isLast = pos.sequence >= sequencesRef.current.length - 1;
      if (isLast && !autoLoop) {
        return false;
      }
      // Advance first, so pausing during the wait can't retype this one.
      pos.sequence = isLast ? 0 : pos.sequence + 1;
      pos.char = 0;
      pos.deleting = false;
      await wait(isLast ? loopDelay : delay);
      show("");
      return true;
    };

    const phrase = async () => {
      const list = sequencesRef.current;
      // `sequences` may have shrunk past the current phrase: start over.
      if (pos.sequence >= list.length) {
        pos.sequence = 0;
        pos.char = 0;
        pos.deleting = false;
      }
      const sequence = list[pos.sequence];
      if (!sequence) {
        return false;
      }
      const { text } = sequence;
      pos.char = Math.min(pos.char, text.length);
      // Resuming after a pause: put the screen back in step.
      show(text.slice(0, pos.char));

      if (!pos.deleting) {
        while (pos.char < text.length) {
          await typeChar(text);
        }
        const pause = sequence.pauseAfter ?? pauseBeforeDelete;
        const isLast = pos.sequence === list.length - 1;
        // Looping deletes the last phrase too, instead of it vanishing.
        if (!(sequence.deleteAfter || (isLast && autoLoop))) {
          return advance(pause);
        }
        await wait(pause);
        pos.deleting = true;
      }
      await erase(text);
      return advance(NEXT_SEQUENCE_DELAY);
    };

    const run = async () => {
      try {
        await wait(startDelay);
        while (await phrase()) {
          // On to the next phrase.
        }
      } catch (error) {
        if (!(error instanceof Stopped)) {
          throw error;
        }
      }
    };
    run();

    const caret = caretRef.current;
    return () => {
      stopped = true;
      for (const timer of timers) {
        clearTimeout(timer);
      }
      clearTimeout(idleTimer);
      if (caret) {
        caret.dataset.idle = "true";
      }
    };
  }, [
    // Content comes through sequencesRef, so a new array with the same
    // phrases doesn't restart the effect.
    typingSpeed,
    deleteSpeed,
    pauseBeforeDelete,
    autoLoop,
    loopDelay,
    startDelay,
    naturalVariance,
    deleteMode,
    typos,
    shouldReduceMotion,
    isRunning,
  ]);

  const kept = screen.text.slice(0, screen.text.length - screen.selected);
  const selected = screen.text.slice(kept.length);

  return (
    <Component
      className={cn(
        "@container flex w-full items-center justify-center font-mono text-black tracking-tight dark:text-white",
        className
      )}
    >
      <style href="kokonutui-type-writer" precedence="default">
        {CARET_KEYFRAMES}
      </style>
      {/* Screen readers get every phrase once instead of whatever partial
          string is on screen. */}
      <span className="sr-only">
        {sequences.map((sequence) => sequence.text).join(", ")}
      </span>
      <motion.span
        animate={{ opacity: 1 }}
        aria-hidden="true"
        className={cn(
          // Every phrase sits invisibly in the same grid cell, so the box is
          // as wide as the widest one as rendered (proportional fonts, CJK)
          // and the text grows from a fixed left edge.
          "inline-grid justify-items-start whitespace-pre pr-[0.25em] @2xl:text-6xl @lg:text-5xl text-4xl leading-[1.2]",
          textClassName
        )}
        initial={{ opacity: 0 }}
        ref={ref}
        transition={{ duration: 0.5 }}
      >
        {sequences.map((sequence, index) => (
          <span
            className="invisible col-start-1 row-start-1"
            // biome-ignore lint/suspicious/noArrayIndexKey: phrases can repeat; the list is static.
            key={index}
          >
            {sequence.text}
          </span>
        ))}
        <span className="col-start-1 row-start-1 min-h-[1.2em]">
          {kept}
          <Caret caretRef={caretRef} />
          {selected && (
            <span className="rounded-[0.08em] bg-sky-500/25 dark:bg-sky-400/30">
              {selected}
            </span>
          )}
        </span>
      </motion.span>
    </Component>
  );
}

/**
 * Takes no room, so the text never shifts when the caret moves to the start
 * of a selection. Solid while typing; blinks once idle.
 */
function Caret({ caretRef }: { caretRef: Ref<HTMLSpanElement> }) {
  return (
    <span className="relative inline-block w-0">
      <span
        className="absolute bottom-[-0.1em] left-[0.04em] h-[1.05em] w-[0.08em] min-w-[2px] bg-current motion-safe:data-[idle=true]:animate-[kokonutui-typewriter-caret_1s_linear_infinite]"
        data-idle="true"
        ref={caretRef}
      />
    </span>
  );
}
```


---

# Avatar Picker
> Generated avatars from a name, morphing as you type, on a 3D coin you can flick, tap or shuffle.

Source: https://kokonutui.com/docs/inputs/avatar-picker

## Installation

```bash
npx shadcn@latest add @kokonutui/avatar-picker
```

## Source

```tsx
// biome-ignore-all lint/suspicious/noBitwiseOperators: the seed hash and PRNG are bitwise by design.
"use client";

/**
 * @author: @dorianbaffier
 * @description: Avatar Picker
 * @version: 2.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { ArrowRight, Dices } from "lucide-react";
import {
  type AnimationPlaybackControls,
  animate,
  LayoutGroup,
  MotionConfig,
  type MotionValue,
  motion,
  useMotionValue,
  useMotionValueEvent,
  useReducedMotion,
  useSpring,
  useTransform,
} from "motion/react";
import {
  type KeyboardEvent,
  type PointerEvent,
  type RefObject,
  useCallback,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

/* ----------------------------------------------------------------------------
 * Face generation
 *
 * Every avatar is a pure function of a seed string. The seed is hashed into a
 * PRNG, which picks continuous feature values (head proportions, hair, eyes,
 * brows, mouth) and a few colors from small muted palettes. Because features
 * are numbers rather than parts picked from a list, two faces can be blended,
 * which is what makes the live morph possible.
 * ------------------------------------------------------------------------- */

type RGB = readonly [number, number, number];

const BACKGROUNDS: readonly { name: string; rgb: RGB }[] = [
  { name: "gray", rgb: [228, 228, 231] },
  { name: "sand", rgb: [233, 226, 214] },
  { name: "sage", rgb: [217, 225, 213] },
  { name: "slate", rgb: [218, 225, 233] },
  { name: "clay", rgb: [235, 221, 214] },
  { name: "mist", rgb: [226, 223, 233] },
];
const SKINS: readonly RGB[] = [
  [246, 233, 222],
  [236, 210, 187],
  [214, 176, 142],
  [176, 128, 96],
  [128, 88, 66],
];
const HAIRS: readonly RGB[] = [
  [39, 39, 42],
  [63, 45, 36],
  [113, 84, 62],
  [161, 161, 170],
  [82, 82, 91],
];
const SHIRTS: readonly RGB[] = [
  [39, 39, 42],
  [82, 82, 91],
  [113, 113, 122],
  [244, 244, 245],
];
const INK = "#18181b";

const SHAPE_KEYS = [
  "headW",
  "headH",
  "headSquare",
  "chin",
  "hairVolume",
  "hairFringe",
  "hairPart",
  "hairLength",
  "eyeGap",
  "eyeY",
  "eyeRx",
  "eyeRy",
  "browTilt",
  "browLift",
  "browWeight",
  "mouthW",
  "mouthCurve",
  "mouthOpen",
  "nose",
  "glasses",
  "cheeks",
  "shoulders",
] as const;

type ShapeKey = (typeof SHAPE_KEYS)[number];

export interface Face {
  shape: Record<ShapeKey, number>;
  bg: RGB;
  skin: RGB;
  hair: RGB;
  shirt: RGB;
  /** Plain-language summary, used for screen-reader labels. */
  description: string;
}

function hashString(input: string) {
  let h = 2_166_136_261;
  for (let i = 0; i < input.length; i++) {
    h ^= input.charCodeAt(i);
    h = Math.imul(h, 16_777_619);
  }
  return h >>> 0;
}

function mulberry32(seed: number) {
  let a = seed;
  return () => {
    a = (a + 0x6d_2b_79_f5) | 0;
    let t = Math.imul(a ^ (a >>> 15), 1 | a);
    t ^= t + Math.imul(t ^ (t >>> 7), 61 | t);
    return ((t ^ (t >>> 14)) >>> 0) / 4_294_967_296;
  };
}

const round2 = (v: number) => Math.round(v * 100) / 100;

function pick<T>(list: readonly T[], r: number): T {
  return list[Math.min(list.length - 1, Math.floor(r * list.length))] as T;
}

function describe(shape: Face["shape"], bgName: string) {
  let hair = "short hair";
  if (shape.hairLength > 0.62) {
    hair = "long hair";
  } else if (shape.hairVolume < 0.22) {
    hair = "cropped hair";
  }
  let mouth = "a slight smile";
  if (shape.mouthOpen > 0.5) {
    mouth = "an open smile";
  } else if (shape.mouthCurve > 3.2) {
    mouth = "a wide smile";
  } else if (shape.mouthCurve < 1) {
    mouth = "a calm expression";
  }
  const face = shape.headSquare > 0.55 ? "Square face" : "Round face";
  const glasses = shape.glasses > 0.5 ? ", glasses" : "";
  return `${face}, ${hair}${glasses}, ${mouth}, on ${bgName}`;
}

/** Deterministic face for a seed. Same seed, same face, server and client. */
export function createFace(seed: string): Face {
  const r = mulberry32(hashString(seed));
  const bg = pick(BACKGROUNDS, r());
  const shape: Face["shape"] = {
    headW: 18 + r() * 5,
    headH: 22 + r() * 4,
    headSquare: r(),
    chin: 0.75 + r() * 0.25,
    hairVolume: r(),
    hairFringe: r(),
    hairPart: r() * 2 - 1,
    hairLength: r() ** 1.6,
    eyeGap: 7.5 + r() * 3,
    eyeY: -2 + r() * 4,
    eyeRx: 1.7 + r() * 0.9,
    eyeRy: 1.9 + r() * 1.4,
    browTilt: -2 + r() * 4,
    browLift: 4.2 + r() * 2,
    browWeight: r() < 0.65 ? 1.3 + r() * 0.8 : 0,
    mouthW: 3.5 + r() * 3,
    mouthCurve: r() * 4.5,
    mouthOpen: r() < 0.3 ? 0.6 + r() * 0.4 : 0,
    nose: r(),
    glasses: r() < 0.25 ? 1 : 0,
    cheeks: r(),
    shoulders: r(),
  };
  for (const key of SHAPE_KEYS) {
    shape[key] = round2(shape[key]);
  }
  return {
    shape,
    bg: bg.rgb,
    skin: pick(SKINS, r()),
    hair: pick(HAIRS, r()),
    shirt: pick(SHIRTS, r()),
    description: describe(shape, bg.name),
  };
}

const lerp = (a: number, b: number, t: number) => a + (b - a) * t;

function lerpRgb(a: RGB, b: RGB, t: number): RGB {
  const c = (i: 0 | 1 | 2) =>
    Math.max(0, Math.min(255, Math.round(lerp(a[i], b[i], t))));
  return [c(0), c(1), c(2)];
}

function lerpFace(a: Face, b: Face, t: number): Face {
  const shape = { ...b.shape };
  for (const key of SHAPE_KEYS) {
    shape[key] = lerp(a.shape[key], b.shape[key], t);
  }
  // Colors stop at the target; only shapes may overshoot with the spring.
  const ct = Math.min(1, t);
  return {
    shape,
    bg: lerpRgb(a.bg, b.bg, ct),
    skin: lerpRgb(a.skin, b.skin, ct),
    hair: lerpRgb(a.hair, b.hair, ct),
    shirt: lerpRgb(a.shirt, b.shirt, ct),
    description: b.description,
  };
}

const rgb = (c: RGB, k = 1) =>
  `rgb(${Math.round(c[0] * k)} ${Math.round(c[1] * k)} ${Math.round(c[2] * k)})`;

const n = round2;

/** Rounded blob: `square` blends between an ellipse and a squircle. */
function blobPath(
  cx: number,
  cy: number,
  w: number,
  top: number,
  bottom: number,
  square: number,
  chin = 1
) {
  const k = 0.552 + square * 0.28;
  const kb = k * chin;
  return [
    `M${n(cx)} ${n(cy - top)}`,
    `C${n(cx + k * w)} ${n(cy - top)} ${n(cx + w)} ${n(cy - k * top)} ${n(cx + w)} ${n(cy)}`,
    `C${n(cx + w)} ${n(cy + kb * bottom)} ${n(cx + kb * w)} ${n(cy + bottom)} ${n(cx)} ${n(cy + bottom)}`,
    `C${n(cx - kb * w)} ${n(cy + bottom)} ${n(cx - w)} ${n(cy + kb * bottom)} ${n(cx - w)} ${n(cy)}`,
    `C${n(cx - w)} ${n(cy - k * top)} ${n(cx - k * w)} ${n(cy - top)} ${n(cx)} ${n(cy - top)}Z`,
  ].join("");
}

function hairFrontPath(s: Face["shape"], cx: number, cy: number) {
  const w = s.headW;
  const h = s.headH;
  const v = s.hairVolume;
  const temple = cy - h * 0.12;
  const crown = cy - h - 1.5 - v * 4;
  const side = w + 1.5 + v * 2.5;
  const k = 0.552 + s.headSquare * 0.28;
  const fringeY = cy - h * (0.66 - s.hairFringe * 0.36);
  const partX = cx + s.hairPart * w * 0.55;
  return [
    `M${n(cx - side)} ${n(temple)}`,
    `C${n(cx - side)} ${n(cy - h * k - v * 3)} ${n(cx - k * side)} ${n(crown)} ${n(cx)} ${n(crown)}`,
    `C${n(cx + k * side)} ${n(crown)} ${n(cx + side)} ${n(cy - h * k - v * 3)} ${n(cx + side)} ${n(temple)}`,
    `L${n(cx + w - 1)} ${n(temple)}`,
    `Q${n(cx + w * 0.75)} ${n(fringeY + 1 - s.hairPart * 5)} ${n(partX)} ${n(fringeY - 2.5)}`,
    `Q${n(cx - w * 0.75)} ${n(fringeY + 1 + s.hairPart * 5)} ${n(cx - w + 1)} ${n(temple)}Z`,
  ].join("");
}

function mouthPath(s: Face["shape"], cx: number, y: number) {
  const curve = s.mouthCurve * 2;
  const open = s.mouthOpen * 5;
  return [
    `M${n(cx - s.mouthW)} ${n(y)}`,
    `Q${n(cx)} ${n(y + curve)} ${n(cx + s.mouthW)} ${n(y)}`,
    `Q${n(cx)} ${n(y + curve + open)} ${n(cx - s.mouthW)} ${n(y)}Z`,
  ].join("");
}

interface FaceArtProps {
  face: Face;
  /** Pointer-follow offset for the eyes, in face units. */
  look?: { x: MotionValue<number>; y: MotionValue<number> };
  blinkRef?: RefObject<SVGGElement | null>;
  className?: string;
}

/** The face itself: one SVG, 100×100 units, every number rounded. */
function FaceArt({ face, look, blinkRef, className }: FaceArtProps) {
  const s = face.shape;
  const cx = 50;
  const cy = 50;
  const eyeY = cy + s.eyeY;
  const mouthY = cy + s.headH * 0.5;
  const glassR = Math.max(s.eyeRx, s.eyeRy) + 3.2;
  const neckTop = cy + s.headH - 6;
  const shoulderTop = cy + s.headH + 3;
  const sw = 30 + s.shoulders * 8;

  return (
    <svg
      aria-hidden="true"
      className={cn("block h-full w-full", className)}
      viewBox="12 14 76 76"
    >
      <rect fill={rgb(face.bg)} height="100" width="100" />
      {/* Long hair sits behind the head. */}
      <path
        d={blobPath(
          cx,
          cy - s.headH * 0.15,
          s.headW + 1 + s.hairVolume * 2.5,
          s.headH * 0.85 + s.hairVolume * 4,
          s.headH * 0.15 + s.hairLength * (s.headH + 14),
          s.headSquare * 0.6
        )}
        fill={rgb(face.hair, 0.9)}
      />
      <path
        d={`M${n(cx - sw)} 100C${n(cx - sw)} ${n(shoulderTop + 6)} ${n(cx - sw * 0.55)} ${n(shoulderTop)} ${cx} ${n(shoulderTop)}C${n(cx + sw * 0.55)} ${n(shoulderTop)} ${n(cx + sw)} ${n(shoulderTop + 6)} ${n(cx + sw)} 100Z`}
        fill={rgb(face.shirt)}
      />
      <rect
        fill={rgb(face.skin, 0.9)}
        height={n(shoulderTop - neckTop + 3)}
        rx="3"
        width="12"
        x={cx - 6}
        y={n(neckTop)}
      />
      <ellipse
        cx={n(cx - s.headW)}
        cy={n(cy + 2)}
        fill={rgb(face.skin, 0.95)}
        rx="3"
        ry="4.5"
      />
      <ellipse
        cx={n(cx + s.headW)}
        cy={n(cy + 2)}
        fill={rgb(face.skin, 0.95)}
        rx="3"
        ry="4.5"
      />
      <path
        d={blobPath(cx, cy, s.headW, s.headH, s.headH, s.headSquare, s.chin)}
        fill={rgb(face.skin)}
      />
      <path d={hairFrontPath(s, cx, cy)} fill={rgb(face.hair)} />
      <g fill={INK} opacity={n(0.045 * s.cheeks)}>
        <circle cx={n(cx - s.eyeGap - 3)} cy={n(eyeY + 7)} r="3.4" />
        <circle cx={n(cx + s.eyeGap + 3)} cy={n(eyeY + 7)} r="3.4" />
      </g>
      <g
        stroke={INK}
        strokeLinecap="round"
        strokeOpacity="0.85"
        strokeWidth={n(Math.max(0, s.browWeight))}
      >
        <path
          d={`M${n(cx - s.eyeGap - 3.2)} ${n(eyeY - s.browLift + s.browTilt)}L${n(cx - s.eyeGap + 3.2)} ${n(eyeY - s.browLift - s.browTilt)}`}
        />
        <path
          d={`M${n(cx + s.eyeGap - 3.2)} ${n(eyeY - s.browLift - s.browTilt)}L${n(cx + s.eyeGap + 3.2)} ${n(eyeY - s.browLift + s.browTilt)}`}
        />
      </g>
      <motion.g style={look ? { x: look.x, y: look.y } : undefined}>
        <g
          className="transition-transform duration-75 ease-out"
          ref={blinkRef}
          style={{ transformBox: "fill-box", transformOrigin: "center" }}
        >
          <ellipse
            cx={n(cx - s.eyeGap)}
            cy={n(eyeY)}
            fill={INK}
            rx={n(s.eyeRx)}
            ry={n(s.eyeRy)}
          />
          <ellipse
            cx={n(cx + s.eyeGap)}
            cy={n(eyeY)}
            fill={INK}
            rx={n(s.eyeRx)}
            ry={n(s.eyeRy)}
          />
        </g>
      </motion.g>
      <path
        d={`M${n(cx - 1.5 - s.nose)} ${n(eyeY + 8 + s.nose * 1.5)}Q${cx} ${n(eyeY + 9.5 + s.nose * 1.5)} ${n(cx + 1.5 + s.nose)} ${n(eyeY + 8 + s.nose * 1.5)}`}
        fill="none"
        stroke={INK}
        strokeLinecap="round"
        strokeOpacity="0.35"
        strokeWidth="1.2"
      />
      <path
        d={mouthPath(s, cx, mouthY)}
        fill={INK}
        stroke={INK}
        strokeLinecap="round"
        strokeLinejoin="round"
        strokeWidth="1.6"
      />
      <g
        fill="none"
        opacity={n(Math.max(0, Math.min(1, s.glasses)))}
        stroke={INK}
        strokeWidth="1.2"
      >
        <circle cx={n(cx - s.eyeGap)} cy={n(eyeY)} r={n(glassR)} />
        <circle cx={n(cx + s.eyeGap)} cy={n(eyeY)} r={n(glassR)} />
        <path
          d={`M${n(cx - s.eyeGap + glassR)} ${n(eyeY)}Q${cx} ${n(eyeY - 2)} ${n(cx + s.eyeGap - glassR)} ${n(eyeY)}`}
        />
      </g>
    </svg>
  );
}

const MORPH = { type: "spring", bounce: 0.22, visualDuration: 0.42 } as const;

/**
 * Renders the face for `seed` and, when the seed changes, eases every feature
 * from where it is now to the new values instead of crossfading.
 */
function MorphingFace({
  seed,
  morph = true,
  ...rest
}: Omit<FaceArtProps, "face"> & { seed: string; morph?: boolean }) {
  const [face, setFace] = useState(() => createFace(seed));
  const shownRef = useRef(face);
  const reduceMotion = useReducedMotion();

  useEffect(() => {
    const target = createFace(seed);
    if (!morph || reduceMotion) {
      shownRef.current = target;
      setFace(target);
      return;
    }
    const from = shownRef.current;
    const controls = animate(0, 1, {
      ...MORPH,
      onUpdate: (t) => {
        const next = lerpFace(from, target, t);
        shownRef.current = next;
        setFace(next);
      },
    });
    return () => controls.stop();
  }, [seed, morph, reduceMotion]);

  return <FaceArt face={face} {...rest} />;
}

/* ----------------------------------------------------------------------------
 * Picker
 * ------------------------------------------------------------------------- */

export interface AvatarValue {
  /** The name the faces are generated from. */
  displayName: string;
  /** Which face for that name. Any integer works; each one is a new face. */
  variant: number;
}

export interface AvatarPickerProps {
  /** Controlled value. */
  value?: AvatarValue;
  /** Initial value when uncontrolled. */
  defaultValue?: Partial<AvatarValue>;
  /** Called when the name changes or a face lands. */
  onChange?: (
    value: AvatarValue & { seed: string; description: string }
  ) => void;
  /** Called by the submit button. */
  onComplete?: (value: AvatarValue & { seed: string }) => void;
  /** Form field name; a hidden input carries the avatar seed. */
  name?: string;
  title?: string;
  description?: string;
  submitLabel?: string;
  className?: string;
}

const SLOT_COUNT = 5;
const COIN = 128;
const BEZEL = 176;
const TICKS = 60;
// One face per half turn. Dragging the coin its own width turns it half a turn.
const DEG_PER_PX = 180 / COIN;
const MAX_FLICK_STEPS = 10;
const TAP_SLOP = 4;
const DRAG_SPRING = { type: "spring", stiffness: 140, damping: 22 } as const;
const SHUFFLE_SPRING = { type: "spring", stiffness: 50, damping: 11 } as const;
const FLY = { type: "spring", bounce: 0.18, visualDuration: 0.45 } as const;
const MIN_NAME = 2;

/** The seed string for a name and variant; feed it to `createFace`. */
export function avatarSeed(displayName: string, variant: number) {
  return `${displayName.trim().toLowerCase()}:${variant}`;
}

const pad3 = (v: number) => String(((v % 1000) + 1000) % 1000).padStart(3, "0");

// Bezel tick marks, rounded so server and client markup match.
const TICK_LINES = Array.from({ length: TICKS }, (_, i) => {
  const a = (i / TICKS) * Math.PI * 2;
  const long = i % 5 === 0;
  const r1 = BEZEL / 2 - 3;
  const r0 = r1 - (long ? 7 : 4);
  const c = BEZEL / 2;
  return {
    key: i,
    long,
    x1: round2(c + Math.sin(a) * r0),
    y1: round2(c - Math.cos(a) * r0),
    x2: round2(c + Math.sin(a) * r1),
    y2: round2(c - Math.cos(a) * r1),
  };
});

function useInView(ref: RefObject<HTMLElement | null>) {
  const [active, setActive] = useState(false);
  useEffect(() => {
    const el = ref.current;
    if (!el) {
      return;
    }
    let onScreen = false;
    const update = () => setActive(onScreen && !document.hidden);
    const io = new IntersectionObserver(([entry]) => {
      onScreen = Boolean(entry?.isIntersecting);
      update();
    });
    io.observe(el);
    document.addEventListener("visibilitychange", update);
    return () => {
      io.disconnect();
      document.removeEventListener("visibilitychange", update);
    };
  }, [ref]);
  return active;
}

/** Eyes drift toward the pointer and blink now and then, only while visible. */
function useLivingEyes(
  coinRef: RefObject<HTMLDivElement | null>,
  active: boolean
) {
  const reduceMotion = useReducedMotion();
  const x = useSpring(0, { stiffness: 180, damping: 18 });
  const y = useSpring(0, { stiffness: 180, damping: 18 });
  const blinkRef = useRef<SVGGElement>(null);

  useEffect(() => {
    if (!active || reduceMotion) {
      return;
    }
    const onMove = (e: globalThis.PointerEvent) => {
      const el = coinRef.current;
      if (!el) {
        return;
      }
      const box = el.getBoundingClientRect();
      const dx = e.clientX - (box.left + box.width / 2);
      const dy = e.clientY - (box.top + box.height / 2);
      const dist = Math.hypot(dx, dy) || 1;
      const reach = Math.min(1, dist / 220);
      x.set((dx / dist) * reach * 1.8);
      y.set((dy / dist) * reach * 1.3);
    };
    let timer = 0;
    let open = 0;
    const blink = () => {
      const g = blinkRef.current;
      if (g) {
        g.style.transform = "scaleY(0.1)";
        open = window.setTimeout(() => {
          g.style.transform = "";
        }, 120);
      }
      timer = window.setTimeout(blink, 2600 + Math.random() * 3400);
    };
    timer = window.setTimeout(blink, 1800);
    window.addEventListener("pointermove", onMove, { passive: true });
    return () => {
      window.clearTimeout(timer);
      window.clearTimeout(open);
      if (blinkRef.current) {
        blinkRef.current.style.transform = "";
      }
      window.removeEventListener("pointermove", onMove);
    };
  }, [active, reduceMotion, coinRef, x, y]);

  return { look: { x, y }, blinkRef };
}

interface CoinProps {
  layoutId: string;
  seed: string;
  angle: MotionValue<number>;
  spinning: boolean;
  label: string;
  look: { x: MotionValue<number>; y: MotionValue<number> };
  blinkRef: RefObject<SVGGElement | null>;
  coinRef: RefObject<HTMLDivElement | null>;
  onPointerDown: (e: PointerEvent<HTMLDivElement>) => void;
  onPointerMove: (e: PointerEvent<HTMLDivElement>) => void;
  onPointerUp: (e: PointerEvent<HTMLDivElement>) => void;
  onPointerCancel: (e: PointerEvent<HTMLDivElement>) => void;
}

/**
 * The preview is a coin with real thickness: a stack of discs in 3D. It turns
 * around its vertical axis and swaps faces as it passes edge-on, so a spin
 * reads like a slot reel without any crossfade.
 */
function Coin({
  layoutId,
  seed,
  angle,
  spinning,
  label,
  look,
  blinkRef,
  coinRef,
  ...handlers
}: CoinProps) {
  // Fold the running angle into -90..90 so the front always faces us.
  const tilt = useTransform(angle, (a) => a - 180 * Math.round(a / 180));
  const transform = useTransform(tilt, (t) => `rotateY(${round2(t)}deg)`);
  const shade = useTransform(tilt, (t) => round2((Math.abs(t) / 90) * 0.35));

  return (
    <motion.div
      className="relative z-10 cursor-grab touch-pan-y select-none rounded-full active:cursor-grabbing"
      layoutId={layoutId}
      ref={coinRef}
      style={{ width: COIN, height: COIN, perspective: 600 }}
      transition={FLY}
      {...handlers}
    >
      <motion.div
        aria-label={label}
        className="relative h-full w-full"
        role="img"
        style={{ transform, transformStyle: "preserve-3d" }}
      >
        {[6, 5, 4, 3, 2, 1].map((z) => (
          <div
            aria-hidden="true"
            className="absolute inset-0 rounded-full bg-zinc-300 dark:bg-zinc-600"
            key={z}
            style={{ transform: `translateZ(-${z}px)` }}
          />
        ))}
        <div className="absolute inset-0 overflow-hidden rounded-full ring-1 ring-black/10 ring-inset">
          <MorphingFace
            blinkRef={blinkRef}
            look={look}
            morph={!spinning}
            seed={seed}
          />
          <motion.div
            aria-hidden="true"
            className="absolute inset-0 bg-black"
            style={{ opacity: shade }}
          />
        </div>
      </motion.div>
    </motion.div>
  );
}

function useSpinner(onLand: (steps: number) => void) {
  const angle = useMotionValue(0);
  const [step, setStep] = useState(0);
  const [spinning, setSpinning] = useState(false);
  const controls = useRef<AnimationPlaybackControls | null>(null);
  const stepRef = useRef(0);
  const onLandRef = useRef(onLand);
  onLandRef.current = onLand;

  useMotionValueEvent(angle, "change", (a) => {
    const s = Math.round(a / 180);
    if (s !== stepRef.current) {
      stepRef.current = s;
      setStep(s);
    }
  });

  const land = useCallback(() => {
    controls.current = null;
    const s = Math.round(angle.get() / 180);
    angle.jump(0);
    stepRef.current = 0;
    setStep(0);
    setSpinning(false);
    if (s !== 0) {
      onLandRef.current(s);
    }
  }, [angle]);

  const stop = useCallback(() => {
    controls.current?.stop();
    controls.current = null;
  }, []);

  const spinTo = useCallback(
    (
      steps: number,
      transition: { stiffness: number; damping: number; velocity: number }
    ) => {
      stop();
      setSpinning(true);
      controls.current = animate(angle, steps * 180, {
        type: "spring",
        ...transition,
        restDelta: 0.5,
        restSpeed: 4,
        onComplete: land,
      });
    },
    [angle, land, stop]
  );

  const jumpBy = useCallback(
    (steps: number) => {
      stop();
      angle.jump(steps * 180);
      land();
    },
    [angle, land, stop]
  );

  return { angle, step, spinning, setSpinning, spinTo, jumpBy, stop, land };
}

type Spinner = ReturnType<typeof useSpinner>;

interface DragState {
  id: number;
  x: number;
  start: number;
  moved: boolean;
  samples: { x: number; t: number }[];
}

function releaseTarget(d: DragState, current: number, x: number, t: number) {
  const first = d.samples[0] ?? { x, t };
  const dt = Math.max(16, t - first.t) / 1000;
  const velocity = ((x - first.x) / dt) * DEG_PER_PX;
  const start = Math.round(d.start / 180);
  const projected = Math.round((current + velocity * 0.28) / 180);
  const target = Math.max(
    start - MAX_FLICK_STEPS,
    Math.min(start + MAX_FLICK_STEPS, projected)
  );
  return { target, velocity };
}

/** Drag the coin sideways to turn it; let go and it coasts with momentum. */
function useDragSpin(spinner: Spinner, reduceMotion: boolean | null) {
  const drag = useRef<DragState | null>(null);

  const onPointerDown = (e: PointerEvent<HTMLDivElement>) => {
    if (e.button !== 0) {
      return;
    }
    spinner.stop();
    spinner.setSpinning(true);
    e.currentTarget.setPointerCapture(e.pointerId);
    drag.current = {
      id: e.pointerId,
      x: e.clientX,
      start: spinner.angle.get(),
      moved: false,
      samples: [{ x: e.clientX, t: e.timeStamp }],
    };
  };

  const onPointerMove = (e: PointerEvent<HTMLDivElement>) => {
    const d = drag.current;
    if (!d || d.id !== e.pointerId) {
      return;
    }
    const dx = e.clientX - d.x;
    if (Math.abs(dx) > TAP_SLOP) {
      d.moved = true;
    }
    spinner.angle.set(d.start + dx * DEG_PER_PX);
    d.samples.push({ x: e.clientX, t: e.timeStamp });
    if (d.samples.length > 6) {
      d.samples.shift();
    }
  };

  const onPointerUp = (e: PointerEvent<HTMLDivElement>) => {
    const d = drag.current;
    if (!d || d.id !== e.pointerId) {
      return;
    }
    drag.current = null;
    const current = spinner.angle.get();
    // A tap turns to the next face; a drag coasts on its release speed.
    const { target, velocity } = d.moved
      ? releaseTarget(d, current, e.clientX, e.timeStamp)
      : { target: Math.round(current / 180) + 1, velocity: 900 };
    if (reduceMotion) {
      spinner.jumpBy(target);
    } else {
      spinner.spinTo(target, { ...DRAG_SPRING, velocity });
    }
  };

  return {
    onPointerDown,
    onPointerMove,
    onPointerUp,
    onPointerCancel: onPointerUp,
  };
}

/**
 * Onboarding avatar picker. Faces are generated from the display name, morph
 * live as it is typed, and can be spun like a coin: drag or flick it sideways,
 * tap it, or press shuffle. Five slots keep options to compare; picking one
 * flies it into the preview and sends the previous face back to its slot.
 */
export default function AvatarPicker({
  value,
  defaultValue,
  onChange,
  onComplete,
  name,
  title = "Pick your avatar",
  description = "Made from your name. Spin it or pick one.",
  submitLabel = "Continue",
  className,
}: AvatarPickerProps) {
  const uid = useId();
  const reduceMotion = useReducedMotion();
  const startVariant = defaultValue?.variant ?? 0;
  const [internalName, setInternalName] = useState(
    defaultValue?.displayName ?? "Robin Vale"
  );
  const [slots, setSlots] = useState(() =>
    Array.from({ length: SLOT_COUNT }, (_, i) => startVariant + i * 7)
  );
  const [selected, setSelected] = useState(0);
  const [focusIndex, setFocusIndex] = useState(0);
  const [announcement, setAnnouncement] = useState("");
  const rootRef = useRef<HTMLDivElement>(null);
  const coinRef = useRef<HTMLDivElement>(null);
  const slotRefs = useRef<(HTMLButtonElement | null)[]>([]);

  const displayName = value?.displayName ?? internalName;
  const variant = value?.variant ?? slots[selected] ?? 0;
  const latest = useRef({ displayName, variant, selected });
  latest.current = { displayName, variant, selected };

  // Keep the selected slot in step with a controlled variant.
  const controlledVariant = value?.variant;
  useEffect(() => {
    if (controlledVariant === undefined) {
      return;
    }
    setSlots((prev) =>
      prev[selected] === controlledVariant
        ? prev
        : prev.map((v, i) => (i === selected ? controlledVariant : v))
    );
  }, [controlledVariant, selected]);

  const emit = (next: AvatarValue, announce: boolean) => {
    const seed = avatarSeed(next.displayName, next.variant);
    const face = createFace(seed);
    onChange?.({ ...next, seed, description: face.description });
    if (announce) {
      setAnnouncement(`Avatar: ${face.description}`);
    }
  };

  const spinner = useSpinner((steps) => {
    const {
      displayName: current,
      variant: from,
      selected: slot,
    } = latest.current;
    const next = from + steps;
    setSlots((prev) => prev.map((v, i) => (i === slot ? next : v)));
    emit({ displayName: current, variant: next }, true);
  });
  const dragHandlers = useDragSpin(spinner, reduceMotion);
  const active = useInView(rootRef);
  const { look, blinkRef } = useLivingEyes(coinRef, active);

  const shownVariant = variant + spinner.step;
  const seed = avatarSeed(displayName, shownVariant);

  const shuffle = () => {
    const current = Math.round(spinner.angle.get() / 180);
    const steps = 5 + Math.floor(Math.random() * 4);
    if (reduceMotion) {
      spinner.jumpBy(current + steps);
      return;
    }
    spinner.spinTo(current + steps, {
      ...SHUFFLE_SPRING,
      velocity: steps * 180 * 1.6,
    });
  };

  const choose = (index: number) => {
    if (index === selected) {
      return;
    }
    if (spinner.spinning) {
      spinner.stop();
      spinner.land();
    }
    setSelected(index);
    setFocusIndex(index);
    emit(
      { displayName: latest.current.displayName, variant: slots[index] ?? 0 },
      true
    );
  };

  const onSlotKeyDown = (e: KeyboardEvent<HTMLButtonElement>) => {
    const moves: Record<string, number> = {
      ArrowRight: focusIndex + 1,
      ArrowDown: focusIndex + 1,
      ArrowLeft: focusIndex - 1,
      ArrowUp: focusIndex - 1,
      Home: 0,
      End: SLOT_COUNT - 1,
    };
    const target = moves[e.key];
    if (target === undefined) {
      return;
    }
    e.preventDefault();
    const next = (target + SLOT_COUNT) % SLOT_COUNT;
    setFocusIndex(next);
    slotRefs.current[next]?.focus();
  };

  const setName = (next: string) => {
    if (value === undefined) {
      setInternalName(next);
    }
    emit({ displayName: next, variant }, false);
  };

  const nameOk = displayName.trim().length >= MIN_NAME;
  const bezelRotate = useTransform(
    spinner.angle,
    (a) => `rotate(${round2(a / 15)}deg)`
  );
  const diceRotate = useTransform(
    spinner.angle,
    (a) => `rotate(${round2(a / 4)}deg)`
  );

  return (
    <MotionConfig reducedMotion="user">
      <div
        className={cn(
          "mx-auto w-full max-w-[360px] rounded-2xl border border-zinc-200 bg-white p-5 text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
          className
        )}
        ref={rootRef}
      >
        <div className="space-y-1">
          <h2 className="font-semibold text-base tracking-tight">{title}</h2>
          <p className="text-sm text-zinc-500 dark:text-zinc-400">
            {description}
          </p>
        </div>

        <LayoutGroup id={uid}>
          <div className="mt-5 flex flex-col items-center">
            <div
              className="relative grid place-items-center"
              style={{ width: BEZEL, height: BEZEL }}
            >
              <motion.svg
                aria-hidden="true"
                className="absolute inset-0 text-zinc-300 dark:text-zinc-700"
                style={{ transform: bezelRotate }}
                viewBox={`0 0 ${BEZEL} ${BEZEL}`}
              >
                {TICK_LINES.map((t) => (
                  <line
                    key={t.key}
                    stroke="currentColor"
                    strokeLinecap="round"
                    strokeOpacity={t.long ? 1 : 0.6}
                    strokeWidth={t.long ? 1.5 : 1}
                    x1={t.x1}
                    x2={t.x2}
                    y1={t.y1}
                    y2={t.y2}
                  />
                ))}
              </motion.svg>
              {/* Fixed index mark the bezel turns under. */}
              <div
                aria-hidden="true"
                className="absolute top-0 left-1/2 h-3 w-0.5 -translate-x-1/2 rounded-full bg-zinc-900 dark:bg-zinc-100"
              />
              <Coin
                angle={spinner.angle}
                blinkRef={blinkRef}
                coinRef={coinRef}
                key={selected}
                label={`Selected avatar: ${createFace(seed).description}`}
                layoutId={`face-${selected}`}
                look={look}
                seed={seed}
                spinning={spinner.spinning}
                {...dragHandlers}
              />
            </div>

            <div className="mt-2 flex items-baseline gap-2 text-xs">
              <span className="max-w-[180px] truncate font-medium">
                {displayName.trim() || "Anonymous"}
              </span>
              <span className="font-mono text-zinc-400 tabular-nums dark:text-zinc-500">
                No. {pad3(shownVariant)}
              </span>
            </div>
          </div>

          <div className="mt-5 flex items-center justify-between gap-3">
            <div
              aria-label="Avatar options"
              className="flex gap-2"
              role="toolbar"
            >
              {slots.map((slotVariant, i) => {
                const isSelected = i === selected;
                const slotSeed = avatarSeed(displayName, slotVariant);
                return (
                  <button
                    aria-label={`Option ${i + 1}: ${createFace(slotSeed).description}`}
                    aria-pressed={isSelected}
                    className="group/slot relative size-10 rounded-full outline-none focus-visible:ring-2 focus-visible:ring-zinc-900 focus-visible:ring-offset-2 focus-visible:ring-offset-white dark:focus-visible:ring-zinc-100 dark:focus-visible:ring-offset-zinc-950"
                    // biome-ignore lint/suspicious/noArrayIndexKey: slots are fixed positions.
                    key={i}
                    onClick={() => choose(i)}
                    onFocus={() => setFocusIndex(i)}
                    onKeyDown={onSlotKeyDown}
                    ref={(el) => {
                      slotRefs.current[i] = el;
                    }}
                    tabIndex={i === focusIndex ? 0 : -1}
                    type="button"
                  >
                    {/* The socket stays put; the face flies in and out of it. */}
                    <span
                      aria-hidden="true"
                      className={cn(
                        "absolute inset-0 rounded-full border transition-colors duration-150 ease-out",
                        isSelected
                          ? "border-zinc-300 border-dashed bg-zinc-50 dark:border-zinc-700 dark:bg-zinc-900"
                          : "border-transparent"
                      )}
                    />
                    {isSelected ? (
                      <span
                        aria-hidden="true"
                        className="absolute inset-0 m-auto size-1.5 rounded-full bg-zinc-400 dark:bg-zinc-500"
                      />
                    ) : (
                      <motion.span
                        className="absolute inset-0 overflow-hidden rounded-full ring-1 ring-black/10 ring-inset transition-shadow duration-150 ease-out group-hover/slot:shadow-[0_0_0_2px_rgb(212_212_216)] dark:group-hover/slot:shadow-[0_0_0_2px_rgb(63_63_70)]"
                        layoutId={`face-${i}`}
                        transition={FLY}
                      >
                        <MorphingFace seed={slotSeed} />
                      </motion.span>
                    )}
                  </button>
                );
              })}
            </div>

            <button
              aria-label="Shuffle avatar"
              className="grid size-10 shrink-0 place-items-center rounded-full border border-zinc-200 text-zinc-600 outline-none transition-colors duration-150 ease-out hover:bg-zinc-100 hover:text-zinc-900 focus-visible:ring-2 focus-visible:ring-zinc-900 focus-visible:ring-offset-2 focus-visible:ring-offset-white dark:border-zinc-800 dark:text-zinc-400 dark:focus-visible:ring-zinc-100 dark:focus-visible:ring-offset-zinc-950 dark:hover:bg-zinc-900 dark:hover:text-zinc-100"
              onClick={shuffle}
              title="Shuffle"
              type="button"
            >
              <motion.span
                className="grid place-items-center"
                style={{ transform: diceRotate }}
              >
                <Dices aria-hidden="true" className="size-4" />
              </motion.span>
            </button>
          </div>
        </LayoutGroup>

        <div className="mt-5 space-y-2">
          <label
            className="block font-medium text-sm"
            htmlFor={`${uid}-display-name`}
          >
            Display name
          </label>
          <input
            autoComplete="name"
            className="h-10 w-full rounded-lg border border-zinc-200 bg-transparent px-3 text-sm outline-none transition-colors duration-150 ease-out placeholder:text-zinc-400 focus-visible:border-zinc-400 focus-visible:ring-2 focus-visible:ring-zinc-900/10 dark:border-zinc-800 dark:focus-visible:border-zinc-600 dark:focus-visible:ring-zinc-100/10"
            id={`${uid}-display-name`}
            maxLength={32}
            onChange={(e) => setName(e.target.value)}
            placeholder="Your name"
            spellCheck={false}
            type="text"
            value={displayName}
          />
        </div>

        {name ? (
          <input
            name={name}
            type="hidden"
            value={avatarSeed(displayName, variant)}
          />
        ) : null}

        <button
          className="group/submit mt-4 flex h-10 w-full items-center justify-center gap-1.5 rounded-lg bg-zinc-900 font-medium text-sm text-white outline-none transition-colors duration-150 ease-out hover:bg-zinc-800 focus-visible:ring-2 focus-visible:ring-zinc-900 focus-visible:ring-offset-2 disabled:cursor-not-allowed disabled:opacity-40 dark:bg-zinc-100 dark:text-zinc-900 dark:focus-visible:ring-zinc-100 dark:focus-visible:ring-offset-zinc-950 dark:hover:bg-white"
          disabled={!nameOk}
          onClick={() =>
            onComplete?.({
              displayName: displayName.trim(),
              variant,
              seed: avatarSeed(displayName, variant),
            })
          }
          type="button"
        >
          {submitLabel}
          <ArrowRight
            aria-hidden="true"
            className="size-4 transition-transform duration-150 ease-out group-hover/submit:translate-x-0.5"
          />
        </button>

        <p aria-live="polite" className="sr-only">
          {announcement}
        </p>
      </div>
    </MotionConfig>
  );
}
```


---

# Detent Dial
> Rotary knob that clicks from notch to notch and coasts when flicked, built with React and Motion.

Source: https://kokonutui.com/docs/inputs/detent-dial

## Installation

```bash
npx shadcn@latest add @kokonutui/detent-dial
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Detent Dial
 * @version: 1.0.0
 * @date: 2026-10-13
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  AnimatePresence,
  type AnimationPlaybackControls,
  animate,
  motion,
  useMotionValue,
  useMotionValueEvent,
  useReducedMotion,
  useTransform,
  type Variants,
} from "motion/react";
import {
  type KeyboardEvent,
  type PointerEvent,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// The dial sweeps 270°, from 7:30 to 4:30 on a clock face.
const SWEEP = 270;
const START_ANGLE = -135;
// How far (deg) the knob can be wound past either end. The pull flattens
// out as it approaches this, so it slows down instead of hitting a wall.
const MAX_OVERSHOOT = 16;
// While dragging, the knob is pulled this much toward the nearest notch,
// which is what makes it feel like it clicks from one step to the next.
const DETENT_PULL = 0.65;
const MAX_TICKS = 56;
// The swell that follows the indicator round the ring: extra length (px)
// at its peak, and how many degrees it spreads either side.
const WAVE_HEIGHT = 9;
const WAVE_WIDTH = 12;
// Pointer movement this close to the centre gives wild angle jumps.
const DEAD_ZONE = 14;
// Below this speed (fraction of the range per second) a release just
// settles into the nearest notch instead of coasting.
const FLICK_THRESHOLD = 0.4;
const VELOCITY_WINDOW_MS = 80;
// Seconds of travel a flick is worth: release speed × COAST = distance coasted.
const COAST = 0.3;
const SETTLE_SPRING = { type: "spring", duration: 0.35, bounce: 0.2 } as const;
const EASE_OUT = [0.23, 1, 0.32, 1] as const;

function damp(distance: number, max: number) {
  return max * (1 - Math.exp(-distance / max));
}

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), max);
}

function snap(value: number, min: number, step: number) {
  return Number((Math.round((value - min) / step) * step + min).toFixed(10));
}

function polar(cx: number, cy: number, radius: number, angle: number) {
  const rad = (angle * Math.PI) / 180;
  // Rounded so the server and the browser, whose trig can differ in the
  // last digits, render identical markup.
  return {
    x: Math.round((cx + radius * Math.sin(rad)) * 100) / 100,
    y: Math.round((cy - radius * Math.cos(rad)) * 100) / 100,
  };
}

function pointerAngle(event: PointerEvent, rect: DOMRect) {
  const dx = event.clientX - (rect.left + rect.width / 2);
  const dy = event.clientY - (rect.top + rect.height / 2);
  return {
    angle: (Math.atan2(dx, -dy) * 180) / Math.PI,
    distance: Math.hypot(dx, dy),
  };
}

// navigator.vibrate is a no-op where unsupported (iOS, desktop). On
// Android it gives each notch a faint tick under the finger.
function hapticTick() {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(1);
  }
}

export interface DetentDialProps {
  /** Accessible name, also shown inside the knob. */
  label?: string;
  min?: number;
  max?: number;
  step?: number;
  /** Initial value when uncontrolled. Double-clicking the knob returns here. */
  defaultValue?: number;
  /** Controlled value. */
  value?: number;
  onValueChange?: (value: number) => void;
  /** Formats the readout, the end labels and `aria-valuetext`. */
  formatValue?: (value: number) => string;
  /** Diameter in px. */
  size?: number;
  disabled?: boolean;
  className?: string;
}

export default function DetentDial({
  label = "Temperature",
  min = 16,
  max = 30,
  step = 0.5,
  defaultValue = 21,
  value: valueProp,
  onValueChange,
  formatValue = (v) => `${v.toFixed(1)}°`,
  size = 240,
  disabled = false,
  className,
}: DetentDialProps) {
  const labelId = useId();
  const knobRef = useRef<HTMLDivElement>(null);
  const tickRefs = useRef<(SVGLineElement | null)[]>([]);
  // The length last written to each tick, so a frame only touches the few
  // ticks the swell is actually passing over.
  const tickLengths = useRef<number[]>([]);
  const reduceMotion = useReducedMotion();
  const range = max - min;

  const initial = clamp(valueProp ?? defaultValue, min, max);
  const [value, setValue] = useState(initial);
  const [direction, setDirection] = useState<1 | -1>(1);
  const [grabbing, setGrabbing] = useState(false);
  const committed = useRef(initial);
  const pointerType = useRef("mouse");

  // The raw, unsnapped position in value units. It can run past min/max
  // while winding; everything visual is derived from it.
  const raw = useMotionValue(initial);
  const animation = useRef<AnimationPlaybackControls | null>(null);
  const drag = useRef<{
    id: number;
    // Measured once on grab: reading layout on every move forces the
    // browser to recalculate it after each frame's writes.
    rect: DOMRect;
    lastAngle: number;
    samples: { t: number; v: number }[];
  } | null>(null);

  const rotation = useTransform(raw, (r) => {
    const degPerUnit = range === 0 ? 0 : SWEEP / range;
    if (r < min) {
      return START_ANGLE - damp((min - r) * degPerUnit, MAX_OVERSHOOT);
    }
    if (r > max) {
      return START_ANGLE + SWEEP + damp((r - max) * degPerUnit, MAX_OVERSHOOT);
    }
    const notch = snap(r, min, step);
    const pulled = notch + (r - notch) * (1 - DETENT_PULL);
    return START_ANGLE + (pulled - min) * degPerUnit;
  });

  // Only re-render when the dial crosses into a new notch, not per frame.
  useMotionValueEvent(raw, "change", (r) => {
    const next = clamp(snap(r, min, step), min, max);
    if (next === committed.current) {
      return;
    }
    setDirection(next > committed.current ? 1 : -1);
    committed.current = next;
    setValue(next);
    onValueChange?.(next);
    if (pointerType.current === "touch") {
      hapticTick();
    }
  });

  // Follow a controlled value when the parent changes it.
  useEffect(() => {
    if (valueProp === undefined || drag.current) {
      return;
    }
    const next = clamp(valueProp, min, max);
    if (next !== committed.current) {
      animation.current?.stop();
      committed.current = next;
      setValue(next);
      raw.jump(next);
    }
  }, [valueProp, min, max, raw]);

  useEffect(() => () => animation.current?.stop(), []);

  const settleTo = (target: number) => {
    animation.current?.stop();
    animation.current = animate(
      raw,
      target,
      reduceMotion ? { duration: 0 } : SETTLE_SPRING
    );
  };

  // Keyboard and wheel steps jump straight to the value. They repeat fast,
  // and an animation on each would trail behind the input.
  const stepBy = (delta: number) => {
    animation.current?.stop();
    const target = clamp(snap(committed.current + delta, min, step), min, max);
    pointerType.current = "keyboard";
    raw.jump(target);
  };

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    if (disabled || drag.current) {
      return;
    }
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    const rect = event.currentTarget.getBoundingClientRect();
    const { angle } = pointerAngle(event, rect);
    animation.current?.stop();
    pointerType.current = event.pointerType;
    event.currentTarget.setPointerCapture(event.pointerId);
    drag.current = {
      id: event.pointerId,
      rect,
      lastAngle: angle,
      samples: [{ t: event.timeStamp, v: raw.get() }],
    };
    setGrabbing(true);
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    const current = drag.current;
    if (!current || current.id !== event.pointerId) {
      return;
    }
    const { angle, distance } = pointerAngle(event, current.rect);
    if (distance < DEAD_ZONE) {
      current.lastAngle = angle;
      return;
    }
    // Unwrap so crossing 6 o'clock doesn't read as a 360° jump.
    let delta = angle - current.lastAngle;
    if (delta > 180) {
      delta -= 360;
    } else if (delta < -180) {
      delta += 360;
    }
    current.lastAngle = angle;
    const next = raw.get() + (delta / SWEEP) * range;
    raw.set(next);
    current.samples.push({ t: event.timeStamp, v: next });
    while (
      current.samples.length > 2 &&
      event.timeStamp - current.samples[0].t > VELOCITY_WINDOW_MS
    ) {
      current.samples.shift();
    }
  };

  const handlePointerUp = (event: PointerEvent<HTMLDivElement>) => {
    const current = drag.current;
    if (!current || current.id !== event.pointerId) {
      return;
    }
    drag.current = null;
    setGrabbing(false);

    const first = current.samples[0];
    const last = current.samples.at(-1) ?? first;
    const elapsed = (last.t - first.t) / 1000;
    // Holding still before letting go is a placement, not a flick.
    const paused = event.timeStamp - last.t > VELOCITY_WINDOW_MS;
    const velocity = elapsed > 0 && !paused ? (last.v - first.v) / elapsed : 0;
    const position = raw.get();
    const inBounds = position >= min && position <= max;

    if (
      reduceMotion ||
      !inBounds ||
      Math.abs(velocity) < range * FLICK_THRESHOLD
    ) {
      settleTo(clamp(snap(position, min, step), min, max));
      return;
    }
    // A flick coasts, slows down, and lands on a notch. If it runs out of
    // room it bounces off the end instead of stopping dead.
    animation.current?.stop();
    // Project where the flick would coast to, land that on a notch, then
    // spring there carrying the release velocity. If the projection runs
    // past an end, the spring overshoots it a little and settles back.
    const target = clamp(
      snap(position + velocity * COAST, min, step),
      min,
      max
    );
    animation.current = animate(raw, target, {
      type: "spring",
      velocity,
      stiffness: 140,
      damping: 24,
      restDelta: 0.005,
    });
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    if (disabled) {
      return;
    }
    const big = Math.max(step, snap(range / 10, 0, step));
    const keySteps: Record<string, number> = {
      ArrowUp: step,
      ArrowRight: step,
      ArrowDown: -step,
      ArrowLeft: -step,
      PageUp: big,
      PageDown: -big,
      Home: min - committed.current,
      End: max - committed.current,
    };
    if (!(event.key in keySteps)) {
      return;
    }
    event.preventDefault();
    stepBy(keySteps[event.key]);
  };

  // The wheel only turns the dial once it has focus, so scrolling the page
  // past it never changes the value by accident. The listener is attached
  // once and reads the latest props through a ref.
  const wheelStep = useRef({ disabled, step, stepBy });
  wheelStep.current = { disabled, step, stepBy };
  useEffect(() => {
    const knob = knobRef.current;
    if (!knob) {
      return;
    }
    let accumulated = 0;
    const onWheel = (event: WheelEvent) => {
      const latest = wheelStep.current;
      if (latest.disabled || document.activeElement !== knob) {
        return;
      }
      event.preventDefault();
      accumulated += event.deltaY;
      // Trackpads send many tiny deltas; one notch per ~40px of scroll.
      while (Math.abs(accumulated) >= 40) {
        const sign = Math.sign(accumulated);
        accumulated -= sign * 40;
        latest.stepBy(-sign * latest.step);
      }
    };
    knob.addEventListener("wheel", onWheel, { passive: false });
    return () => knob.removeEventListener("wheel", onWheel);
  }, []);

  const center = size / 2;
  const tickCount = Math.max(1, Math.min(Math.round(range / step), MAX_TICKS));
  const valueFraction = range === 0 ? 0 : (value - min) / range;
  const activeTick = Math.round(valueFraction * tickCount);
  const knobSize = size * 0.64;
  const outer = size / 2 - 6;

  // Ticks swell as the indicator passes them, following its exact angle
  // (not the snapped value), so a wave travels round the ring as you turn.
  function tickLength(i: number, indicatorAngle: number) {
    const angle = START_ANGLE + (i / tickCount) * SWEEP;
    const major = i === 0 || i === tickCount || i % 5 === 0;
    const distance = (angle - indicatorAngle) / WAVE_WIDTH;
    // Rounded to a tenth of a pixel: finer changes aren't visible, and
    // skipping them leaves most ticks untouched on any given frame.
    return (
      Math.round(
        ((major ? 10 : 6) + WAVE_HEIGHT * Math.exp(-distance * distance)) * 10
      ) / 10
    );
  }

  function tickGeometry(i: number, length: number) {
    const angle = START_ANGLE + (i / tickCount) * SWEEP;
    return {
      a: polar(center, center, outer - length, angle),
      b: polar(center, center, outer, angle),
    };
  }

  // Written straight to the lines each frame; no re-render while turning.
  useMotionValueEvent(rotation, "change", (indicatorAngle) => {
    for (let i = 0; i <= tickCount; i++) {
      const line = tickRefs.current[i];
      const length = tickLength(i, indicatorAngle);
      if (!line || tickLengths.current[i] === length) {
        continue;
      }
      tickLengths.current[i] = length;
      const { a } = tickGeometry(i, length);
      line.setAttribute("x1", String(a.x));
      line.setAttribute("y1", String(a.y));
    }
  });
  const minLabel = polar(center, center, outer + 2, START_ANGLE - 12);
  const maxLabel = polar(center, center, outer + 2, START_ANGLE + SWEEP + 12);

  return (
    <div
      className={cn(
        "relative select-none",
        disabled && "opacity-50",
        className
      )}
      style={{ width: size, height: size }}
    >
      <svg
        aria-hidden="true"
        className="absolute inset-0"
        height={size}
        viewBox={`0 0 ${size} ${size}`}
        width={size}
      >
        {Array.from({ length: tickCount + 1 }, (_, i) => {
          const lit = i <= activeTick;
          const length = tickLength(i, rotation.get());
          tickLengths.current[i] = length;
          const { a, b } = tickGeometry(i, length);
          return (
            <line
              className={cn(
                "transition-[stroke] duration-150",
                lit
                  ? "stroke-zinc-900 dark:stroke-zinc-100"
                  : "stroke-zinc-300 dark:stroke-zinc-700"
              )}
              // biome-ignore lint/suspicious/noArrayIndexKey: ticks are positional.
              key={i}
              ref={(node) => {
                tickRefs.current[i] = node;
              }}
              strokeLinecap="round"
              strokeWidth={1.5}
              x1={a.x}
              x2={b.x}
              y1={a.y}
              y2={b.y}
            />
          );
        })}
      </svg>

      <span
        aria-hidden="true"
        className="absolute -translate-x-1/2 text-[11px] text-zinc-400 tabular-nums"
        style={{ left: minLabel.x, top: minLabel.y }}
      >
        {formatValue(min)}
      </span>
      <span
        aria-hidden="true"
        className="absolute -translate-x-1/2 text-[11px] text-zinc-400 tabular-nums"
        style={{ left: maxLabel.x, top: maxLabel.y }}
      >
        {formatValue(max)}
      </span>

      <div
        aria-disabled={disabled || undefined}
        aria-labelledby={labelId}
        aria-valuemax={max}
        aria-valuemin={min}
        aria-valuenow={value}
        aria-valuetext={formatValue(value)}
        className={cn(
          "absolute top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 touch-none rounded-full outline-none",
          "border border-zinc-200 bg-white shadow-[0_1px_2px_rgb(0_0_0/0.06),0_12px_32px_-12px_rgb(0_0_0/0.25)] dark:border-zinc-800 dark:bg-zinc-900 dark:shadow-[0_1px_2px_rgb(0_0_0/0.4),0_12px_32px_-12px_rgb(0_0_0/0.8)]",
          "transition-[border-color] duration-150 focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-offset-4 focus-visible:ring-offset-white dark:focus-visible:ring-offset-zinc-950",
          grabbing
            ? "cursor-grabbing border-zinc-300 dark:border-zinc-700"
            : "cursor-grab",
          disabled && "cursor-not-allowed"
        )}
        onDoubleClick={() => {
          if (!disabled) {
            pointerType.current = "mouse";
            settleTo(clamp(defaultValue, min, max));
          }
        }}
        onKeyDown={handleKeyDown}
        onLostPointerCapture={handlePointerUp}
        onPointerCancel={handlePointerUp}
        onPointerDown={handlePointerDown}
        onPointerMove={handlePointerMove}
        onPointerUp={handlePointerUp}
        ref={knobRef}
        role="slider"
        style={{ width: knobSize, height: knobSize }}
        tabIndex={disabled ? -1 : 0}
      >
        {/* Only the indicator turns; the readout stays upright. */}
        <motion.div
          aria-hidden="true"
          className="absolute inset-0"
          style={{ rotate: rotation }}
        >
          <span className="absolute top-2.5 left-1/2 h-3 w-[3px] -translate-x-1/2 rounded-full bg-zinc-900 dark:bg-zinc-100" />
        </motion.div>

        <div className="pointer-events-none absolute inset-0 flex flex-col items-center justify-center">
          <span
            className="text-xs text-zinc-500 dark:text-zinc-400"
            id={labelId}
          >
            {label}
          </span>
          <RollingValue
            direction={direction}
            reduceMotion={Boolean(reduceMotion)}
            text={formatValue(value)}
          />
        </div>
      </div>
    </div>
  );
}

/**
 * Each character rolls on its own, so going from 21.5 to 22.0 only moves
 * the digits that changed. A touch of blur hides the overlap between the
 * outgoing and incoming glyph.
 */
// `custom` is the signed offset of the latest change. AnimatePresence hands
// the current value to the leaving glyph too, so it always exits opposite to
// the one coming in.
const rollVariants: Variants = {
  // A full transform string rather than `y`, so Motion can hand the roll to
  // the compositor instead of stepping it on the main thread.
  enter: (offset: number) => ({
    opacity: 0,
    transform: `translateY(${offset}px)`,
    filter: offset === 0 ? "blur(0px)" : "blur(2px)",
  }),
  center: { opacity: 1, transform: "translateY(0px)", filter: "blur(0px)" },
  exit: (offset: number) => ({
    opacity: 0,
    transform: `translateY(${-offset}px)`,
    filter: offset === 0 ? "blur(0px)" : "blur(2px)",
  }),
};

function RollingValue({
  text,
  direction,
  reduceMotion,
}: {
  text: string;
  direction: 1 | -1;
  reduceMotion: boolean;
}) {
  const offset = reduceMotion ? 0 : direction * 10;
  return (
    <span
      aria-hidden="true"
      className="relative flex font-medium text-3xl text-zinc-900 tabular-nums tracking-tight dark:text-zinc-100"
    >
      {text.split("").map((char, index) => (
        <span
          className="relative inline-flex overflow-hidden"
          // Position is the identity: the same slot keeps its node.
          // biome-ignore lint/suspicious/noArrayIndexKey: characters are positional.
          key={index}
        >
          <AnimatePresence custom={offset} initial={false} mode="popLayout">
            <motion.span
              animate="center"
              custom={offset}
              exit="exit"
              initial="enter"
              key={char}
              transition={{ duration: 0.16, ease: EASE_OUT }}
              variants={rollVariants}
            >
              {char}
            </motion.span>
          </AnimatePresence>
        </span>
      ))}
    </span>
  );
}
```


---

# File Upload
> Drag and drop file upload with animated progress, file validation and error states. Built with React, Tailwind CSS and Motion animations.

Source: https://kokonutui.com/docs/inputs/file-upload

## Installation

```bash
npx shadcn@latest add @kokonutui/file-upload
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: File Upload
 * @version: 1.0.0
 * @date: 2025-06-26
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { UploadCloud } from "lucide-react";
import { AnimatePresence, motion, useReducedMotion } from "motion/react";
import {
  type DragEvent,
  useCallback,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

type FileStatus = "idle" | "dragging" | "uploading" | "error";

interface FileError {
  message: string;
  code: string;
}

interface UploadHelpers {
  /** Report upload progress from 0 to 100. */
  onProgress: (percent: number) => void;
  /** Aborted when the user cancels or the component unmounts. */
  signal: AbortSignal;
}

interface FileUploadProps {
  /**
   * Performs the real upload. Resolve to report success, reject to report an
   * error. When omitted, the upload is simulated over `uploadDelay`.
   */
  onUpload?: (file: File, helpers: UploadHelpers) => Promise<void>;
  onUploadSuccess?: (file: File) => void;
  onUploadError?: (error: FileError) => void;
  acceptedFileTypes?: string[];
  maxFileSize?: number;
  currentFile?: File | null;
  onFileRemove?: () => void;
  /** Duration in milliseconds of the simulated upload used without `onUpload`. Defaults to 2000ms; 0 completes immediately. */
  uploadDelay?: number;
  validateFile?: (file: File) => FileError | null;
  className?: string;
}

const DEFAULT_MAX_FILE_SIZE = 5 * 1024 * 1024; // 5MB
const UPLOAD_STEP_SIZE = 5;
const ERROR_RESET_DELAY = 3000;
const PROGRESS_MASK_RADIUS = 60;
const PROGRESS_MASK_CIRCUMFERENCE = 2 * Math.PI * PROGRESS_MASK_RADIUS;
const FILE_SIZES = [
  "Bytes",
  "KB",
  "MB",
  "GB",
  "TB",
  "PB",
  "EB",
  "ZB",
  "YB",
] as const;

// Accepts exact MIME types ("image/png"), wildcards ("image/*") and
// extensions (".pdf"), like the input's `accept` attribute.
const matchesAcceptedType = (file: File, acceptedType: string): boolean => {
  const accepted = acceptedType.trim().toLowerCase();
  if (!accepted) {
    return false;
  }
  if (accepted.startsWith(".")) {
    return file.name.toLowerCase().endsWith(accepted);
  }
  const fileType = file.type.toLowerCase();
  if (accepted.endsWith("/*")) {
    return fileType.startsWith(accepted.slice(0, -1));
  }
  return fileType === accepted;
};

// Labels for the hint line: ".pdf" -> "PDF", "image/svg+xml" -> "SVG",
// "image/*" -> "any image".
const describeAcceptedType = (acceptedType: string): string => {
  const accepted = acceptedType.trim();
  if (accepted.startsWith(".")) {
    return accepted.slice(1).toUpperCase();
  }
  const [kind = "", subtype = ""] = accepted.split("/");
  if (subtype === "*") {
    return `any ${kind.toLowerCase()}`;
  }
  return subtype.split("+")[0].toUpperCase();
};

const describeAcceptedTypes = (acceptedTypes: string[]): string => {
  const labels = acceptedTypes.map(describeAcceptedType).filter(Boolean);
  const text = labels.length ? labels.join(", ") : "any file";
  return text.charAt(0).toUpperCase() + text.slice(1);
};

const clampProgress = (value: number) => Math.min(Math.max(value, 0), 100);

// Module constant, so the default does not change identity every render.
const NO_ACCEPTED_TYPES: string[] = [];

const formatBytes = (bytes: number, decimals = 2): string => {
  if (!+bytes) {
    return "0 Bytes";
  }
  const k = 1024;
  const dm = decimals < 0 ? 0 : decimals;
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  const unit = FILE_SIZES[i] || FILE_SIZES.at(-1);
  return `${Number.parseFloat((bytes / k ** i).toFixed(dm))} ${unit}`;
};

const EASE_OUT = [0.23, 1, 0.32, 1] as const;

// The illustration rests on its first frame and only bobs while a file is
// dragged over the card. SMIL ignores prefers-reduced-motion, so that is
// checked here too. Pausing happens in an effect, so markup is unaffected.
const UploadIllustration = ({ animate }: { animate: boolean }) => {
  const svgRef = useRef<SVGSVGElement>(null);
  const shouldReduceMotion = useReducedMotion();

  useEffect(() => {
    const svg = svgRef.current;
    if (!svg) {
      return;
    }
    if (animate && !shouldReduceMotion) {
      svg.unpauseAnimations();
    } else {
      svg.pauseAnimations();
      svg.setCurrentTime(0);
    }
  }, [animate, shouldReduceMotion]);

  return (
    <div className="relative h-16 w-16">
      <svg
        aria-hidden="true"
        className="h-full w-full"
        fill="none"
        ref={svgRef}
        viewBox="0 0 100 100"
        xmlns="http://www.w3.org/2000/svg"
      >
        <circle
          className="stroke-gray-200 dark:stroke-gray-700"
          cx="50"
          cy="50"
          r="45"
          strokeDasharray="4 4"
          strokeWidth="2"
        >
          <animateTransform
            attributeName="transform"
            dur="60s"
            from="0 50 50"
            repeatCount="indefinite"
            to="360 50 50"
            type="rotate"
          />
        </circle>

        <path
          className="fill-blue-100 stroke-blue-500 dark:fill-blue-900/30 dark:stroke-blue-400"
          d="M30 35H70C75 35 75 40 75 40V65C75 70 70 70 70 70H30C25 70 25 65 25 65V40C25 35 30 35 30 35Z"
          strokeWidth="2"
        >
          <animate
            attributeName="d"
            dur="2s"
            repeatCount="indefinite"
            values="
                        M30 35H70C75 35 75 40 75 40V65C75 70 70 70 70 70H30C25 70 25 65 25 65V40C25 35 30 35 30 35Z;
                        M30 38H70C75 38 75 43 75 43V68C75 73 70 73 70 73H30C25 73 25 68 25 68V43C25 38 30 38 30 38Z;
                        M30 35H70C75 35 75 40 75 40V65C75 70 70 70 70 70H30C25 70 25 65 25 65V40C25 35 30 35 30 35Z"
          />
        </path>

        <path
          className="stroke-blue-500 dark:stroke-blue-400"
          d="M30 35C30 35 35 35 40 35C45 35 45 30 50 30C55 30 55 35 60 35C65 35 70 35 70 35"
          fill="none"
          strokeWidth="2"
        />

        <g className="translate-y-2">
          <line
            className="stroke-blue-500 dark:stroke-blue-400"
            strokeLinecap="round"
            strokeWidth="2"
            x1="50"
            x2="50"
            y1="45"
            y2="60"
          >
            <animate
              attributeName="y2"
              dur="2s"
              repeatCount="indefinite"
              values="60;55;60"
            />
          </line>
          <polyline
            className="stroke-blue-500 dark:stroke-blue-400"
            fill="none"
            points="42,52 50,45 58,52"
            strokeLinecap="round"
            strokeLinejoin="round"
            strokeWidth="2"
          >
            <animate
              attributeName="points"
              dur="2s"
              repeatCount="indefinite"
              values="42,52 50,45 58,52;42,47 50,40 58,47;42,52 50,45 58,52"
            />
          </polyline>
        </g>
      </svg>
    </div>
  );
};

// Concentric rings that spin in alternating directions, phase-shifted by a
// short delay. The progress mask reveals them as the upload advances.
const PROGRESS_RINGS = [
  { r: 120, stroke: "#FF3D71", delay: 0 },
  { r: 110, stroke: "#4ADE80", delay: 0.2 },
  { r: 100, stroke: "#2196F3", delay: 0.3 },
  { r: 90, stroke: "#FFA726", delay: 0.2 },
  { r: 80, stroke: "#FF1493", delay: 0.5 },
  { r: 70, stroke: "#FFEB3B", delay: 0.3 },
  { r: 60, stroke: "#00BCD4", delay: 0.7 },
  { r: 50, stroke: "#FF4081", delay: 0.2 },
  { r: 40, stroke: "#76FF03", delay: 0.3 },
  { r: 30, stroke: "#448AFF", delay: 0.5 },
  { r: 20, stroke: "#FF3D00", delay: 0 },
] as const;

const UploadingAnimation = ({
  progress,
  maskId,
}: {
  progress: number;
  maskId: string;
}) => (
  <div
    aria-label="Upload progress"
    aria-valuemax={100}
    aria-valuemin={0}
    aria-valuenow={Math.round(progress)}
    className="relative h-16 w-16"
    role="progressbar"
  >
    <svg
      aria-hidden="true"
      className="h-full w-full"
      fill="none"
      viewBox="0 0 240 240"
      xmlns="http://www.w3.org/2000/svg"
    >
      <defs>
        <mask id={maskId}>
          <rect fill="black" height="240" width="240" />
          {/* Dim track so the rings stay visible before progress is reported */}
          <circle cx="120" cy="120" fill="white" opacity="0.2" r="120" />
          {/* A stroke as wide as the disk turns the dash into a growing pie slice */}
          <circle
            cx="120"
            cy="120"
            fill="none"
            r={PROGRESS_MASK_RADIUS}
            stroke="white"
            strokeDasharray={`${(clampProgress(progress) / 100) * PROGRESS_MASK_CIRCUMFERENCE} ${PROGRESS_MASK_CIRCUMFERENCE}`}
            strokeWidth={PROGRESS_MASK_RADIUS * 2}
            transform="rotate(-90 120 120)"
          />
        </mask>
      </defs>

      <g mask={`url(#${maskId})`} strokeDasharray="18% 40%" strokeWidth="10">
        {PROGRESS_RINGS.map((ring, i) => (
          <circle
            className="origin-[120px_120px] animate-spin motion-reduce:animate-none"
            cx="120"
            cy="120"
            key={ring.r}
            opacity="0.95"
            r={ring.r}
            stroke={ring.stroke}
            style={{
              animationDelay: `${ring.delay}s`,
              animationDirection: i % 2 === 0 ? "normal" : "reverse",
              animationDuration: "8s",
            }}
          />
        ))}
      </g>
    </svg>
  </div>
);

export default function FileUpload({
  onUpload,
  onUploadSuccess,
  onUploadError,
  acceptedFileTypes = NO_ACCEPTED_TYPES,
  maxFileSize = DEFAULT_MAX_FILE_SIZE,
  currentFile: initialFile = null,
  onFileRemove,
  uploadDelay = 2000,
  validateFile,
  className,
}: FileUploadProps) {
  const [file, setFile] = useState<File | null>(initialFile);
  const [status, setStatus] = useState<FileStatus>("idle");
  const [progress, setProgress] = useState(0);
  const [error, setError] = useState<FileError | null>(null);
  const fileInputRef = useRef<HTMLInputElement>(null);
  const progressMaskId = useId();
  const uploadIntervalRef = useRef<ReturnType<typeof setInterval> | null>(null);
  const uploadAbortRef = useRef<AbortController | null>(null);
  const errorTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(null);

  const clearUploadInterval = useCallback(() => {
    if (uploadIntervalRef.current) {
      clearInterval(uploadIntervalRef.current);
      uploadIntervalRef.current = null;
    }
  }, []);

  const cancelUpload = useCallback(() => {
    clearUploadInterval();
    uploadAbortRef.current?.abort();
    uploadAbortRef.current = null;
  }, [clearUploadInterval]);

  const clearErrorTimeout = useCallback(() => {
    if (errorTimeoutRef.current) {
      clearTimeout(errorTimeoutRef.current);
      errorTimeoutRef.current = null;
    }
  }, []);

  useEffect(
    () => () => {
      cancelUpload();
      clearErrorTimeout();
    },
    [cancelUpload, clearErrorTimeout]
  );

  const validateFileSize = useCallback(
    (file: File): FileError | null => {
      if (file.size > maxFileSize) {
        return {
          message: `File size exceeds ${formatBytes(maxFileSize)}`,
          code: "FILE_TOO_LARGE",
        };
      }
      return null;
    },
    [maxFileSize]
  );

  const validateFileType = useCallback(
    (file: File): FileError | null => {
      if (!acceptedFileTypes?.length) {
        return null;
      }

      if (!acceptedFileTypes.some((type) => matchesAcceptedType(file, type))) {
        return {
          message: `File type must be ${acceptedFileTypes.join(", ")}`,
          code: "INVALID_FILE_TYPE",
        };
      }
      return null;
    },
    [acceptedFileTypes]
  );

  const handleError = useCallback(
    (error: FileError) => {
      clearErrorTimeout();
      setError(error);
      setStatus("error");
      onUploadError?.(error);

      errorTimeoutRef.current = setTimeout(() => {
        errorTimeoutRef.current = null;
        setError(null);
        setStatus("idle");
      }, ERROR_RESET_DELAY);
    },
    [clearErrorTimeout, onUploadError]
  );

  const startUpload = useCallback(
    (uploadingFile: File) => {
      cancelUpload();
      const controller = new AbortController();
      uploadAbortRef.current = controller;

      // Never report success for an upload that was cancelled or replaced.
      const completeUpload = () => {
        if (controller.signal.aborted) {
          return;
        }
        uploadAbortRef.current = null;
        setProgress(0);
        setStatus("idle");
        setFile(null);
        onUploadSuccess?.(uploadingFile);
      };

      const failUpload = (uploadError: unknown) => {
        if (controller.signal.aborted) {
          return;
        }
        uploadAbortRef.current = null;
        handleError({
          message:
            uploadError instanceof Error && uploadError.message
              ? uploadError.message
              : "Upload failed",
          code: "UPLOAD_FAILED",
        });
      };

      if (onUpload) {
        const onProgress = (percent: number) => {
          if (!controller.signal.aborted) {
            setProgress(clampProgress(percent));
          }
        };
        Promise.resolve()
          .then(() =>
            onUpload(uploadingFile, { onProgress, signal: controller.signal })
          )
          .then(completeUpload, failUpload);
        return;
      }

      // Demo fallback: simulate an upload over `uploadDelay`.
      if (uploadDelay <= 0) {
        completeUpload();
        return;
      }
      let currentProgress = 0;
      uploadIntervalRef.current = setInterval(
        () => {
          currentProgress += UPLOAD_STEP_SIZE;
          if (currentProgress >= 100) {
            clearUploadInterval();
            completeUpload();
          } else {
            setProgress(currentProgress);
          }
        },
        uploadDelay / (100 / UPLOAD_STEP_SIZE)
      );
    },
    [
      cancelUpload,
      clearUploadInterval,
      handleError,
      onUpload,
      onUploadSuccess,
      uploadDelay,
    ]
  );

  const handleFileSelect = useCallback(
    (selectedFile: File | null) => {
      if (!selectedFile) {
        return;
      }

      // Reset error state
      clearErrorTimeout();
      setError(null);

      const sizeError = validateFileSize(selectedFile);
      if (sizeError) {
        handleError(sizeError);
        return;
      }

      const typeError = validateFileType(selectedFile);
      if (typeError) {
        handleError(typeError);
        return;
      }

      const customError = validateFile?.(selectedFile);
      if (customError) {
        handleError(customError);
        return;
      }

      setFile(selectedFile);
      setStatus("uploading");
      setProgress(0);
      startUpload(selectedFile);
    },
    [
      clearErrorTimeout,
      startUpload,
      validateFileSize,
      validateFileType,
      validateFile,
      handleError,
    ]
  );

  // The drag handlers sit on the always-mounted card so `preventDefault` runs
  // in every state; otherwise dropping during an upload makes the browser
  // open the file. The drop zone stays usable while an error shows.
  const canDrop = status !== "uploading";

  const handleDragOver = useCallback(
    (e: DragEvent<HTMLDivElement>) => {
      e.preventDefault();
      e.stopPropagation();
      e.dataTransfer.dropEffect = canDrop ? "copy" : "none";
      if (status === "idle" || status === "error") {
        setStatus("dragging");
      }
    },
    [canDrop, status]
  );

  const handleDragLeave = useCallback((e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    // Moving onto a child element also fires dragleave; ignore it.
    if (
      e.relatedTarget instanceof Node &&
      e.currentTarget.contains(e.relatedTarget)
    ) {
      return;
    }
    setStatus((prev) => (prev === "dragging" ? "idle" : prev));
  }, []);

  const handleDrop = useCallback(
    (e: DragEvent<HTMLDivElement>) => {
      e.preventDefault();
      e.stopPropagation();
      if (!canDrop) {
        return;
      }
      setStatus("idle");
      const droppedFile = e.dataTransfer.files?.[0];
      if (droppedFile) {
        handleFileSelect(droppedFile);
      }
    },
    [canDrop, handleFileSelect]
  );

  const handleFileInputChange = useCallback(
    (e: React.ChangeEvent<HTMLInputElement>) => {
      const selectedFile = e.target.files?.[0];
      handleFileSelect(selectedFile || null);
      if (e.target) {
        e.target.value = "";
      }
    },
    [handleFileSelect]
  );

  const triggerFileInput = useCallback(() => {
    if (status === "uploading") {
      return;
    }
    fileInputRef.current?.click();
  }, [status]);

  const resetState = useCallback(() => {
    cancelUpload();
    setFile(null);
    setStatus("idle");
    setProgress(0);
    onFileRemove?.();
  }, [cancelUpload, onFileRemove]);

  return (
    <div className={cn("relative mx-auto w-full max-w-sm", className)}>
      {/* biome-ignore lint/a11y/noStaticElementInteractions lint/a11y/noNoninteractiveElementInteractions: pointer drop target; keyboard users have the Upload File button */}
      <div
        className="group relative w-full rounded-xl bg-white p-0.5 ring-1 ring-gray-200 dark:bg-black dark:ring-white/10"
        onDragEnter={handleDragOver}
        onDragLeave={handleDragLeave}
        onDragOver={handleDragOver}
        onDrop={handleDrop}
      >
        <div className="absolute inset-x-0 -top-px h-px w-full bg-gradient-to-r from-transparent via-blue-500/20 to-transparent" />

        <div className="relative w-full rounded-[10px] bg-gray-50/50 p-1.5 dark:bg-white/[0.02]">
          <div
            className={cn(
              "relative mx-auto w-full overflow-hidden rounded-lg border border-gray-100 bg-white dark:border-white/[0.08] dark:bg-black/50",
              error && "border-red-500/50 dark:border-red-500/50"
            )}
          >
            <div
              className={cn(
                "absolute inset-0 transition-opacity duration-150",
                status === "dragging" ? "opacity-100" : "opacity-0"
              )}
            >
              <div className="absolute inset-x-0 top-0 h-[20%] bg-gradient-to-b from-blue-500/10 to-transparent" />
              <div className="absolute inset-x-0 bottom-0 h-[20%] bg-gradient-to-t from-blue-500/10 to-transparent" />
              <div className="absolute inset-y-0 left-0 w-[20%] bg-gradient-to-r from-blue-500/10 to-transparent" />
              <div className="absolute inset-y-0 right-0 w-[20%] bg-gradient-to-l from-blue-500/10 to-transparent" />
              <div className="absolute inset-[20%] rounded-lg bg-blue-500/5" />
            </div>

            <div className="relative h-[240px]">
              <AnimatePresence mode="wait">
                {status !== "uploading" && (
                  <motion.div
                    animate={{
                      opacity: status === "dragging" ? 0.8 : 1,
                      y: 0,
                      scale: status === "dragging" ? 0.98 : 1,
                    }}
                    className="motion-reduce:transform-none! absolute inset-0 flex flex-col items-center justify-center p-6"
                    exit={{
                      opacity: 0,
                      y: -10,
                      transition: { duration: 0.12, ease: EASE_OUT },
                    }}
                    initial={{ opacity: 0, y: 10 }}
                    key="dropzone"
                    transition={{ duration: 0.2, ease: EASE_OUT }}
                  >
                    <div className="mb-4">
                      <UploadIllustration animate={status === "dragging"} />
                    </div>

                    <div className="mb-4 space-y-1.5 text-center">
                      <h3 className="font-semibold text-gray-900 text-lg tracking-tight dark:text-white">
                        Drag and drop or
                      </h3>
                      <p className="text-gray-500 text-xs dark:text-gray-400">
                        {describeAcceptedTypes(acceptedFileTypes)}
                        {maxFileSize > 0 &&
                          Number.isFinite(maxFileSize) &&
                          ` up to ${formatBytes(maxFileSize)}`}
                      </p>
                    </div>

                    <button
                      className="group/button flex w-4/5 items-center justify-center gap-2 rounded-lg bg-gray-100 px-4 py-2.5 font-semibold text-gray-900 text-sm transition-[color,background-color,scale] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] hover:bg-gray-200 motion-safe:active:scale-[0.97] dark:bg-white/10 dark:text-white dark:hover:bg-white/20"
                      onClick={triggerFileInput}
                      type="button"
                    >
                      <span>Upload File</span>
                      <UploadCloud className="h-4 w-4 transition-transform duration-200 motion-safe:group-hover/button:scale-110" />
                    </button>

                    {/* The error replaces this line, so the drop zone stays
                        usable and the layout does not shift. */}
                    {error ? (
                      <p
                        className="mt-3 text-center text-red-500 text-xs dark:text-red-400"
                        role="alert"
                      >
                        {error.message}
                      </p>
                    ) : (
                      <p className="mt-3 text-gray-500 text-xs dark:text-gray-400">
                        or drag and drop your file here
                      </p>
                    )}

                    {/* Hidden: the Upload File button opens it, so it adds
                        no extra tab stop. */}
                    <input
                      accept={acceptedFileTypes.join(",")}
                      className="hidden"
                      onChange={handleFileInputChange}
                      ref={fileInputRef}
                      type="file"
                    />
                  </motion.div>
                )}
                {status === "uploading" && (
                  <motion.div
                    animate={{ opacity: 1, scale: 1 }}
                    className="motion-reduce:transform-none! absolute inset-0 flex flex-col items-center justify-center p-6"
                    exit={{
                      opacity: 0,
                      scale: 0.95,
                      transition: { duration: 0.12, ease: EASE_OUT },
                    }}
                    initial={{ opacity: 0, scale: 0.95 }}
                    key="uploading"
                    transition={{ duration: 0.2, ease: EASE_OUT }}
                  >
                    <div className="mb-4">
                      <UploadingAnimation
                        maskId={progressMaskId}
                        progress={progress}
                      />
                    </div>

                    <div className="mb-4 space-y-1.5 text-center">
                      <h3 className="truncate font-semibold text-gray-900 text-sm dark:text-white">
                        {file?.name}
                      </h3>
                      <div className="flex items-center justify-center gap-2 text-xs">
                        <span className="text-gray-500 dark:text-gray-400">
                          {formatBytes(file?.size || 0)}
                        </span>
                        <span className="font-medium text-blue-500">
                          {Math.round(progress)}%
                        </span>
                      </div>
                    </div>

                    <button
                      className="flex w-4/5 items-center justify-center gap-2 rounded-lg bg-gray-100 px-4 py-2.5 font-semibold text-gray-900 text-sm transition-[color,background-color,scale] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] hover:bg-gray-200 motion-safe:active:scale-[0.97] dark:bg-white/10 dark:text-white dark:hover:bg-white/20"
                      onClick={resetState}
                      type="button"
                    >
                      Cancel
                    </button>
                  </motion.div>
                )}
              </AnimatePresence>
            </div>
          </div>
        </div>
      </div>
    </div>
  );
}

FileUpload.displayName = "FileUpload";
```


---

# Liquid Slider
> A vertical slider you fill like a glass, with a sloshing surface and rising bubbles.

Source: https://kokonutui.com/docs/inputs/liquid-slider

## Installation

```bash
npx shadcn@latest add @kokonutui/liquid-slider
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Liquid Slider
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  useCallback,
  useEffect,
  useId,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

const WIDTH = 280;
const HEIGHT = 360;
// The glass is a cylinder seen from a little above: its rim and floor are
// ellipses RY tall, its walls run from LEFT to RIGHT.
const LEFT = 84;
const RIGHT = 196;
const CX = (LEFT + RIGHT) / 2;
const RADIUS = (RIGHT - LEFT) / 2;
const RY = 9;
const RIM_Y = 104;
const FLOOR_Y = 312;
// Where the surface sits when the glass is empty and when it is full.
const EMPTY_Y = FLOOR_Y;
const FULL_Y = RIM_Y + 16;

// The surface is a row of columns that each bob up and down and pull on
// their neighbours: a 1D wave. Heights in px, time in seconds.
const COLUMNS = 34;
const STEP = 1 / 120;
const SPREAD = 2600;
const TENSION = 30;
const DAMPING = 2.4;
// Neighbouring columns drag on each other's speed, which smooths out
// the short, jagged ripples and leaves the long sloshes.
const VISCOSITY = 22;
const MAX_WAVE = 16;
// While dragging, the surface under the finger is pulled towards it this
// hard, and the finger's sideways speed piles the liquid up ahead of it.
const GRAB = 900;
const GRAB_REACH = 2.6;
const GRAB_MAX = 14;
const STIR = 0.55;
// The level chases its target on a spring: fast, but not instant, so a quick
// drag leaves the liquid behind the finger for a moment.
const LEVEL_STIFFNESS = 220;
const LEVEL_DAMPING = 26;
const MAX_BUBBLES = 14;
const REST_EPSILON = 0.02;

interface Bubble {
  x: number;
  y: number;
  r: number;
  speed: number;
  phase: number;
}

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), max);
}

function haptic() {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(4);
  }
}

// How far in front of / behind the centre line the surface ellipse reaches at
// each column, precomputed and rounded so server and browser markup match.
const COLUMN_X: number[] = [];
const DEPTH: number[] = [];
for (let i = 0; i < COLUMNS; i++) {
  const t = i / (COLUMNS - 1);
  const x = LEFT + t * (RIGHT - LEFT);
  COLUMN_X.push(Math.round(x * 100) / 100);
  const u = (x - CX) / RADIUS;
  DEPTH.push(Math.round(RY * Math.sqrt(Math.max(0, 1 - u * u)) * 100) / 100);
}

function levelToY(level: number) {
  return EMPTY_Y - level * (EMPTY_Y - FULL_Y);
}

function f(n: number) {
  return n.toFixed(2);
}

/** The top of the liquid: from the back edge across, then the front back. */
function surfacePath(levelY: number, heights: Float64Array) {
  let d = "";
  for (let i = 0; i < COLUMNS; i++) {
    const y = Math.min(levelY + heights[i] - DEPTH[i], FLOOR_Y);
    d += `${i === 0 ? "M" : "L"}${f(COLUMN_X[i])} ${f(y)}`;
  }
  for (let i = COLUMNS - 1; i >= 0; i--) {
    const y = Math.min(levelY + heights[i] + DEPTH[i], FLOOR_Y + DEPTH[i]);
    d += `L${f(COLUMN_X[i])} ${f(y)}`;
  }
  return `${d}Z`;
}

/** The body: the front edge of the surface, down the wall, along the floor. */
function bodyPath(levelY: number, heights: Float64Array) {
  let d = "";
  for (let i = 0; i < COLUMNS; i++) {
    const y = Math.min(levelY + heights[i] + DEPTH[i], FLOOR_Y + DEPTH[i]);
    d += `${i === 0 ? "M" : "L"}${f(COLUMN_X[i])} ${f(y)}`;
  }
  d += `L${RIGHT} ${FLOOR_Y} A${RADIUS} ${RY} 0 0 1 ${LEFT} ${FLOOR_Y}Z`;
  return d;
}

/** A thin line along the front lip, where light catches the surface. */
function lipPath(levelY: number, heights: Float64Array) {
  let d = "";
  for (let i = 1; i < COLUMNS - 1; i++) {
    const y = Math.min(levelY + heights[i] + DEPTH[i], FLOOR_Y + DEPTH[i]);
    d += `${i === 1 ? "M" : "L"}${f(COLUMN_X[i])} ${f(y)}`;
  }
  return d;
}

/** Surface height (px from the level) at an x, between two columns. */
function heightAt(heights: Float64Array, x: number) {
  const t = clamp((x - LEFT) / (RIGHT - LEFT), 0, 1) * (COLUMNS - 1);
  const i = Math.floor(t);
  const j = Math.min(i + 1, COLUMNS - 1);
  return heights[i] + (heights[j] - heights[i]) * (t - i);
}

const FLAT = new Float64Array(COLUMNS);

export interface LiquidSliderProps {
  value?: number;
  defaultValue?: number;
  onValueChange?: (value: number) => void;
  min?: number;
  max?: number;
  step?: number;
  /** Shown after the number. */
  unit?: string;
  label?: string;
  /** Formats the readout and `aria-valuetext`. */
  formatValue?: (value: number) => string;
  className?: string;
}

const defaultFormat = (value: number) => value.toLocaleString("en-US");

export default function LiquidSlider({
  value: valueProp,
  defaultValue = 1250,
  onValueChange,
  min = 0,
  max = 2000,
  step = 50,
  unit = "ml",
  label = "Water today",
  formatValue = defaultFormat,
  className,
}: LiquidSliderProps) {
  const [internal, setInternal] = useState(defaultValue);
  const value = clamp(valueProp ?? internal, min, max);
  const [dragging, setDragging] = useState(false);
  const labelId = useId();

  const surfaceRef = useRef<SVGPathElement>(null);
  const bodyRef = useRef<SVGPathElement>(null);
  const lipRef = useRef<SVGPathElement>(null);
  const bubblesRef = useRef<(SVGCircleElement | null)[]>([]);
  const svgRef = useRef<SVGSVGElement>(null);

  const fraction = (max - min > 0 ? (value - min) / (max - min) : 0) || 0;
  const initialY = levelToY(fraction);

  const sim = useRef({
    heights: new Float64Array(COLUMNS),
    speeds: new Float64Array(COLUMNS),
    accels: new Float64Array(COLUMNS),
    level: fraction,
    levelSpeed: 0,
    target: fraction,
    bubbles: [] as Bubble[],
    raf: 0,
    last: 0,
    carry: 0,
    // Pointer, while held: where it is, in drawing units, and its sideways
    // speed.
    held: false,
    px: 0,
    py: 0,
    pvx: 0,
    lastPx: 0,
    lastT: 0,
    reduceMotion: false,
    seed: 1,
  });

  // Handlers outlive the render they came from; read the props here.
  const latest = useRef({ value, min, max, step, onValueChange });
  latest.current = { value, min, max, step, onValueChange };

  const commit = useCallback(
    (next: number) => {
      const { min: lo, max: hi, step: inc } = latest.current;
      const snapped = clamp(
        Number((Math.round((next - lo) / inc) * inc + lo).toFixed(10)),
        lo,
        hi
      );
      if (snapped === latest.current.value) {
        return;
      }
      // A light tick each time the level crosses a quarter.
      const quarter = (hi - lo) / 4;
      if (
        Math.floor((snapped - lo) / quarter) !==
        Math.floor((latest.current.value - lo) / quarter)
      ) {
        haptic();
      }
      latest.current.value = snapped;
      if (valueProp === undefined) {
        setInternal(snapped);
      }
      latest.current.onValueChange?.(snapped);
    },
    [valueProp]
  );

  const random = useCallback(() => {
    // Deterministic, so bubbles never depend on Math.random during render.
    const s = sim.current;
    s.seed = (s.seed * 16_807) % 2_147_483_647;
    return s.seed / 2_147_483_647;
  }, []);

  const draw = useCallback(() => {
    const s = sim.current;
    const y = levelToY(s.level);
    surfaceRef.current?.setAttribute("d", surfacePath(y, s.heights));
    bodyRef.current?.setAttribute("d", bodyPath(y, s.heights));
    lipRef.current?.setAttribute("d", lipPath(y, s.heights));
    for (let i = 0; i < MAX_BUBBLES; i++) {
      const el = bubblesRef.current[i];
      const b = s.bubbles[i];
      if (!el) {
        continue;
      }
      if (b) {
        const wobble = Math.sin(b.phase) * 1.6;
        el.setAttribute("cx", f(b.x + wobble));
        el.setAttribute("cy", f(b.y));
        el.setAttribute("r", f(b.r));
        el.style.opacity = "1";
      } else {
        el.style.opacity = "0";
      }
    }
  }, []);

  // The level rides a spring towards its target. When it rises fast, the
  // pour drags bubbles in from the floor.
  const stepLevel = useCallback(() => {
    const s = sim.current;
    const force =
      (s.target - s.level) * LEVEL_STIFFNESS - s.levelSpeed * LEVEL_DAMPING;
    s.levelSpeed += force * STEP;
    s.level += s.levelSpeed * STEP;
    if (
      s.levelSpeed > 0.5 &&
      s.bubbles.length < MAX_BUBBLES &&
      random() < s.levelSpeed * 0.05
    ) {
      s.bubbles.push({
        x: LEFT + 10 + random() * (RIGHT - LEFT - 20),
        y: FLOOR_Y + 2,
        r: 1.2 + random() * 2,
        speed: 40 + random() * 50,
        phase: random() * Math.PI * 2,
      });
    }
  }, [random]);

  // One step of the wave: each column accelerates towards its neighbours'
  // average and back to rest, then the volume is re-levelled so the waves
  // only move liquid around.
  const stepWaves = useCallback(() => {
    const s = sim.current;
    const { heights: h, speeds: v, accels: a } = s;
    const levelY = levelToY(s.level);
    let mean = 0;
    for (let i = 0; i < COLUMNS; i++) {
      const l = i === 0 ? 0 : i - 1;
      const r = i === COLUMNS - 1 ? i : i + 1;
      let accel =
        SPREAD * (h[l] + h[r] - 2 * h[i]) +
        VISCOSITY * (v[l] + v[r] - 2 * v[i]) -
        TENSION * h[i] -
        DAMPING * v[i];
      if (s.held) {
        const reach = (COLUMN_X[i] - s.px) / ((RIGHT - LEFT) / COLUMNS);
        const weight = Math.exp(-(reach * reach) / (GRAB_REACH * GRAB_REACH));
        const pull = clamp(s.py - (levelY + h[i]), -GRAB_MAX, GRAB_MAX);
        accel += GRAB * pull * weight * 0.05;
        accel -= STIR * s.pvx * ((i - (COLUMNS - 1) / 2) / COLUMNS) * 60;
      }
      a[i] = accel;
    }
    for (let i = 0; i < COLUMNS; i++) {
      v[i] += a[i] * STEP;
      h[i] = clamp(h[i] + v[i] * STEP, -MAX_WAVE, MAX_WAVE);
      mean += h[i];
    }
    mean /= COLUMNS;
    let energy = 0;
    for (let i = 0; i < COLUMNS; i++) {
      h[i] -= mean;
      energy += Math.abs(h[i]) + Math.abs(v[i]) * STEP;
    }
    return energy / COLUMNS;
  }, []);

  // Bubbles rise with a wobble and pop at the surface, leaving a ripple.
  const stepBubbles = useCallback(() => {
    const s = sim.current;
    const levelY = levelToY(s.level);
    for (let i = s.bubbles.length - 1; i >= 0; i--) {
      const b = s.bubbles[i];
      b.y -= b.speed * STEP;
      b.phase += STEP * 9;
      if (b.y <= levelY + heightAt(s.heights, b.x) + 1) {
        const col = Math.round(((b.x - LEFT) / (RIGHT - LEFT)) * (COLUMNS - 1));
        s.speeds[clamp(col, 0, COLUMNS - 1)] -= 30 * b.r;
        s.bubbles.splice(i, 1);
      }
    }
  }, []);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      s.carry += elapsed;
      let energy = 0;
      while (s.carry >= STEP) {
        stepLevel();
        energy = stepWaves();
        stepBubbles();
        s.carry -= STEP;
      }
      // The sideways speed fades when the pointer stops moving.
      s.pvx *= 0.85;
      draw();
      const settled =
        !s.held &&
        energy < REST_EPSILON &&
        Math.abs(s.target - s.level) < 0.0005 &&
        Math.abs(s.levelSpeed) < 0.001 &&
        s.bubbles.length === 0;
      if (settled) {
        s.level = s.target;
        s.heights.fill(0);
        s.speeds.fill(0);
        s.last = 0;
        draw();
        return;
      }
      s.raf = requestAnimationFrame(tick);
    },
    [draw, stepBubbles, stepLevel, stepWaves]
  );

  const wake = useCallback(() => {
    const s = sim.current;
    if (s.reduceMotion) {
      s.level = s.target;
      s.levelSpeed = 0;
      s.heights.fill(0);
      s.speeds.fill(0);
      s.bubbles.length = 0;
      draw();
      return;
    }
    if (!s.raf) {
      s.raf = requestAnimationFrame(tick);
    }
  }, [draw, tick]);

  useEffect(() => {
    const s = sim.current;
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = query.matches;
    const onChange = () => {
      s.reduceMotion = query.matches;
    };
    query.addEventListener("change", onChange);
    // Pause while the tab is hidden; the loop picks up again on return.
    const onVisibility = () => {
      if (document.hidden && s.raf) {
        cancelAnimationFrame(s.raf);
        s.raf = 0;
        s.last = 0;
      } else if (!document.hidden) {
        wake();
      }
    };
    document.addEventListener("visibilitychange", onVisibility);
    return () => {
      query.removeEventListener("change", onChange);
      document.removeEventListener("visibilitychange", onVisibility);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, [wake]);

  // A value set from outside (a controlled prop, or a keypress) moves the
  // target; the liquid follows on its own.
  useEffect(() => {
    const s = sim.current;
    if (s.held) {
      return;
    }
    if (Math.abs(s.target - fraction) > 1e-6) {
      s.target = fraction;
      wake();
    }
  }, [fraction, wake]);

  const localPoint = (event: PointerEvent) => {
    const rect = svgRef.current?.getBoundingClientRect();
    if (!rect) {
      return { x: 0, y: 0 };
    }
    return {
      x: ((event.clientX - rect.left) / rect.width) * WIDTH,
      y: ((event.clientY - rect.top) / rect.height) * HEIGHT,
    };
  };

  const follow = (event: PointerEvent) => {
    const s = sim.current;
    const point = localPoint(event);
    const now = event.timeStamp;
    if (s.lastT && now > s.lastT) {
      const vx = ((point.x - s.lastPx) / (now - s.lastT)) * 1000;
      s.pvx = s.pvx * 0.6 + clamp(vx, -900, 900) * 0.4;
    }
    s.lastPx = point.x;
    s.lastT = now;
    s.px = clamp(point.x, LEFT, RIGHT);
    s.py = clamp(point.y, FULL_Y, EMPTY_Y);
    const raw = clamp((EMPTY_Y - point.y) / (EMPTY_Y - FULL_Y), 0, 1);
    s.target = raw;
    const { min: lo, max: hi } = latest.current;
    commit(lo + raw * (hi - lo));
    wake();
  };

  const handlePointerDown = (event: PointerEvent<SVGSVGElement>) => {
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    event.preventDefault();
    // Focus without scrolling, so the keyboard picks up where the hand left.
    (event.currentTarget.parentElement as HTMLElement | null)?.focus({
      preventScroll: true,
    });
    event.currentTarget.setPointerCapture(event.pointerId);
    const s = sim.current;
    s.held = true;
    s.lastT = 0;
    s.pvx = 0;
    setDragging(true);
    follow(event);
  };

  const handlePointerMove = (event: PointerEvent<SVGSVGElement>) => {
    if (sim.current.held) {
      follow(event);
    }
  };

  const handlePointerUp = () => {
    const s = sim.current;
    if (!s.held) {
      return;
    }
    s.held = false;
    setDragging(false);
    // Settle on the step the readout shows.
    const { value: v, min: lo, max: hi } = latest.current;
    s.target = hi - lo > 0 ? (v - lo) / (hi - lo) : 0;
    wake();
  };

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    const { min: lo, max: hi, step: inc } = latest.current;
    const big = Math.max(inc, (hi - lo) / 10);
    const moves: Record<string, number> = {
      ArrowUp: value + inc,
      ArrowRight: value + inc,
      ArrowDown: value - inc,
      ArrowLeft: value - inc,
      PageUp: value + big,
      PageDown: value - big,
      Home: lo,
      End: hi,
    };
    const next = Object.hasOwn(moves, event.key) ? moves[event.key] : null;
    if (next === null) {
      return;
    }
    event.preventDefault();
    commit(next);
    // A drop in the middle, so the key gets a ripple too.
    const s = sim.current;
    if (!s.reduceMotion) {
      s.speeds[Math.floor(COLUMNS / 2)] += next > value ? -90 : 90;
      wake();
    }
  };

  const ticks = [0, 0.25, 0.5, 0.75, 1];
  const initialSurface = surfacePath(initialY, FLAT);
  const initialBody = bodyPath(initialY, FLAT);
  const initialLip = lipPath(initialY, FLAT);

  return (
    <div
      aria-labelledby={labelId}
      aria-orientation="vertical"
      aria-valuemax={max}
      aria-valuemin={min}
      aria-valuenow={value}
      aria-valuetext={`${formatValue(value)} ${unit}`.trim()}
      className={cn(
        "relative select-none overflow-hidden rounded-3xl border border-zinc-200 bg-white text-zinc-900 outline-none focus-visible:outline-2 focus-visible:outline-zinc-400 focus-visible:outline-offset-2 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      onKeyDown={handleKeyDown}
      role="slider"
      style={{ width: WIDTH, height: HEIGHT }}
      tabIndex={0}
    >
      <div className="pointer-events-none absolute inset-x-0 top-0 p-6">
        <p className="text-sm text-zinc-500" id={labelId}>
          {label}
        </p>
        <p className="mt-0.5 font-medium text-2xl tabular-nums tracking-tight">
          {formatValue(value)}
          <span className="ml-1 text-base text-zinc-400">{unit}</span>
        </p>
      </div>

      <svg
        aria-hidden="true"
        className={cn(
          "absolute inset-0 touch-none",
          dragging ? "cursor-grabbing" : "cursor-grab"
        )}
        height={HEIGHT}
        onLostPointerCapture={handlePointerUp}
        onPointerCancel={handlePointerUp}
        onPointerDown={handlePointerDown}
        onPointerMove={handlePointerMove}
        onPointerUp={handlePointerUp}
        ref={svgRef}
        viewBox={`0 0 ${WIDTH} ${HEIGHT}`}
        width={WIDTH}
      >
        <defs>
          <clipPath id={`${labelId}-glass`}>
            <path
              d={`M${LEFT} ${RIM_Y} L${RIGHT} ${RIM_Y} L${RIGHT} ${FLOOR_Y} A${RADIUS} ${RY} 0 0 1 ${LEFT} ${FLOOR_Y} Z`}
            />
          </clipPath>
        </defs>

        {/* The back of the glass. */}
        <path
          className="fill-zinc-50 dark:fill-zinc-900/60"
          d={`M${LEFT} ${RIM_Y} A${RADIUS} ${RY} 0 0 1 ${RIGHT} ${RIM_Y} L${RIGHT} ${FLOOR_Y} A${RADIUS} ${RY} 0 0 1 ${LEFT} ${FLOOR_Y} Z`}
        />
        <path
          className="fill-none stroke-zinc-200 dark:stroke-zinc-800"
          d={`M${LEFT} ${FLOOR_Y} A${RADIUS} ${RY} 0 0 1 ${RIGHT} ${FLOOR_Y}`}
          strokeWidth={1}
        />

        <g clipPath={`url(#${labelId}-glass)`}>
          <path className="fill-sky-500" d={initialBody} ref={bodyRef} />
          {Array.from({ length: MAX_BUBBLES }, (_, i) => (
            <circle
              className="fill-white/25 stroke-white/70"
              cx={CX}
              cy={FLOOR_Y}
              // biome-ignore lint/suspicious/noArrayIndexKey: a fixed pool of circles reused by index
              key={i}
              r={1}
              ref={(el) => {
                bubblesRef.current[i] = el;
              }}
              strokeWidth={0.75}
              style={{ opacity: 0 }}
            />
          ))}
          <path
            className="fill-sky-300 dark:fill-sky-400"
            d={initialSurface}
            ref={surfaceRef}
          />
          <path
            className="fill-none stroke-white/60"
            d={initialLip}
            ref={lipRef}
            strokeLinecap="round"
            strokeWidth={1}
          />
        </g>

        {/* Graduations, printed on the front of the glass. */}
        {ticks.map((t) => {
          const y = Math.round(levelToY(t) + RY * 0.55);
          const tickValue = min + t * (max - min);
          return (
            <g key={t}>
              <line
                className="stroke-zinc-900/25 dark:stroke-white/30"
                strokeWidth={1}
                x1={RIGHT - 14}
                x2={RIGHT - 4}
                y1={y}
                y2={y}
              />
              <text
                className="fill-zinc-400 text-[10px] tabular-nums dark:fill-zinc-500"
                dominantBaseline="middle"
                x={RIGHT + 8}
                y={y}
              >
                {formatValue(tickValue)}
              </text>
            </g>
          );
        })}

        {/* The glass itself: rim, walls and the front of the floor. */}
        <ellipse
          className="fill-none stroke-zinc-300 dark:stroke-zinc-700"
          cx={CX}
          cy={RIM_Y}
          rx={RADIUS}
          ry={RY}
          strokeWidth={1.5}
        />
        <path
          className="fill-none stroke-zinc-300 dark:stroke-zinc-700"
          d={`M${LEFT} ${RIM_Y} L${LEFT} ${FLOOR_Y} A${RADIUS} ${RY} 0 0 0 ${RIGHT} ${FLOOR_Y} L${RIGHT} ${RIM_Y}`}
          strokeWidth={1.5}
        />
        {/* A strip of reflection down the left wall. */}
        <line
          className="stroke-white/50 dark:stroke-white/10"
          strokeLinecap="round"
          strokeWidth={3}
          x1={LEFT + 9}
          x2={LEFT + 9}
          y1={RIM_Y + 22}
          y2={FLOOR_Y - 14}
        />
      </svg>
    </div>
  );
}
```


---

# Loader
> Animated loading indicator with rotating gradient rings, size variants and customizable title text. Built with React and Tailwind CSS.

Source: https://kokonutui.com/docs/inputs/loader

## Installation

```bash
npx shadcn@latest add @kokonutui/loader
```

## Source

```tsx
import type { CSSProperties } from "react";
import { cn } from "@/lib/utils";

interface LoaderProps
  extends Omit<React.HTMLAttributes<HTMLDivElement>, "title" | "children"> {
  title?: string;
  /** Pass an empty string to show the title alone. */
  subtitle?: string;
  size?: "sm" | "md" | "lg";
}

const SIZE_CONFIG = {
  sm: {
    container: "size-20",
    titleClass: "text-sm font-medium",
    subtitleClass: "text-xs",
    spacing: "space-y-2",
    maxWidth: "max-w-48",
  },
  md: {
    container: "size-32",
    titleClass: "text-base font-medium",
    subtitleClass: "text-sm",
    spacing: "space-y-3",
    maxWidth: "max-w-56",
  },
  lg: {
    container: "size-40",
    titleClass: "text-lg font-semibold",
    subtitleClass: "text-base",
    spacing: "space-y-4",
    maxWidth: "max-w-64",
  },
} as const;

const ringMask = (stops: string) =>
  `radial-gradient(circle at 50% 50%, ${stops})`;

// Rings are tinted with `currentColor`, so one set covers light and dark mode
// and the loader can be recoloured with any `text-*` class.
const RINGS: { id: string; style: CSSProperties }[] = [
  {
    id: "outer",
    style: {
      background:
        "conic-gradient(from 0deg, transparent 0deg, currentColor 90deg, transparent 180deg)",
      mask: ringMask("transparent 35%, black 37%, black 39%, transparent 41%"),
      WebkitMask: ringMask(
        "transparent 35%, black 37%, black 39%, transparent 41%"
      ),
      opacity: 0.8,
      animationDuration: "3s",
    },
  },
  {
    id: "primary",
    style: {
      background:
        "conic-gradient(from 0deg, transparent 0deg, currentColor 120deg, color-mix(in srgb, currentColor 50%, transparent) 240deg, transparent 360deg)",
      mask: ringMask("transparent 42%, black 44%, black 48%, transparent 50%"),
      WebkitMask: ringMask(
        "transparent 42%, black 44%, black 48%, transparent 50%"
      ),
      opacity: 0.9,
      animationDuration: "1.2s",
    },
  },
  {
    id: "counter",
    style: {
      background:
        "conic-gradient(from 180deg, transparent 0deg, color-mix(in srgb, currentColor 60%, transparent) 45deg, transparent 90deg)",
      mask: ringMask("transparent 52%, black 54%, black 56%, transparent 58%"),
      WebkitMask: ringMask(
        "transparent 52%, black 54%, black 56%, transparent 58%"
      ),
      opacity: 0.35,
      animationDuration: "4s",
      animationDirection: "reverse",
    },
  },
  {
    id: "accent",
    style: {
      background:
        "conic-gradient(from 270deg, transparent 0deg, color-mix(in srgb, currentColor 40%, transparent) 20deg, transparent 40deg)",
      mask: ringMask("transparent 61%, black 62%, black 63%, transparent 64%"),
      WebkitMask: ringMask(
        "transparent 61%, black 62%, black 63%, transparent 64%"
      ),
      opacity: 0.5,
      animationDuration: "3.5s",
    },
  },
];

export default function Loader({
  title = "Configuring your account...",
  subtitle = "Please wait while we prepare everything for you",
  size = "md",
  className,
  ...props
}: LoaderProps) {
  const config = SIZE_CONFIG[size];

  return (
    <div
      className={cn(
        "flex flex-col items-center justify-center gap-8 p-8",
        className
      )}
      {...props}
    >
      <div
        aria-hidden="true"
        className={cn("relative text-black dark:text-white", config.container)}
      >
        {RINGS.map((ring) => (
          <div
            className="absolute inset-0 rounded-full motion-safe:animate-spin motion-reduce:animate-pulse"
            key={ring.id}
            style={ring.style}
          />
        ))}
      </div>

      <output
        aria-live="polite"
        className={cn(
          "block text-center starting:opacity-0 transition-opacity duration-200 ease-out",
          config.spacing,
          config.maxWidth
        )}
      >
        <span
          className={cn(
            config.titleClass,
            "block text-black/90 leading-[1.15] tracking-[-0.02em] antialiased dark:text-white/90"
          )}
        >
          {title}
        </span>
        {subtitle && (
          <span
            className={cn(
              config.subtitleClass,
              "block font-normal text-black/60 leading-[1.45] tracking-[-0.01em] antialiased dark:text-white/60"
            )}
          >
            {subtitle}
          </span>
        )}
      </output>
    </div>
  );
}
```


---

# Signature Pad
> A signature field with a sprung pen tip, speed-weighted ink and SVG output.

Source: https://kokonutui.com/docs/inputs/signature-pad

## Installation

```bash
npx shadcn@latest add @kokonutui/signature-pad
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Signature Pad
 * @version: 1.0.0
 * @date: 2026-10-14
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type KeyboardEvent,
  type PointerEvent,
  useCallback,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

// The pen tip trails the pointer on a spring, which irons out the jitter of
// a hand on a trackpad and gives strokes the swing of real ink. Units are
// px and seconds; the simulation runs at a fixed step.
const STEP = 1 / 240;
const TIP_STIFFNESS = 2600;
const TIP_DAMPING = 78;
// Line width follows speed, like a nib: slow is heavy, fast is light.
const MAX_WIDTH = 3.6;
const MIN_WIDTH = 1.1;
const SPEED_FOR_MIN = 1800;
const WIDTH_EASE = 0.08;
// A new point is laid down once the tip has moved this far.
const MIN_GAP = 0.6;
// Strokes start and end thin, over this many points.
const TAPER = 7;
const CLEAR_MS = 420;
// Ballpoint blue. In dark mode the canvas is inverted and hue-rotated, which
// keeps it blue and makes it light.
const INK = "#1e3a8a";

interface Point {
  x: number;
  y: number;
  w: number;
}

type Stroke = Point[];

function clamp(value: number, min: number, max: number) {
  return Math.min(Math.max(value, min), max);
}

/** Width at point i of a stroke, thinned at both ends. */
function taperedWidth(stroke: Stroke, i: number, open: boolean) {
  const n = stroke.length;
  const start = Math.min(1, (i + 1) / TAPER);
  const end = open ? 1 : Math.min(1, (n - i) / TAPER);
  return stroke[i].w * (0.35 + 0.65 * Math.min(start, end));
}

/** Adds a quad to the path, wound the same way as `arc`, so one fill unions them. */
function quad(ctx: CanvasRenderingContext2D, pts: number[]) {
  let area = 0;
  for (let k = 0; k < 8; k += 2) {
    const j = (k + 2) % 8;
    area += pts[k] * pts[j + 1] - pts[j] * pts[k + 1];
  }
  const order = area >= 0 ? [0, 2, 4, 6] : [6, 4, 2, 0];
  ctx.moveTo(pts[order[0]], pts[order[0] + 1]);
  for (let k = 1; k < 4; k++) {
    ctx.lineTo(pts[order[k]], pts[order[k] + 1]);
  }
  ctx.closePath();
}

/**
 * Draws points [from, to) of a stroke as rounded segments, filled as one
 * shape so the joins don't show seams.
 */
function paint(
  ctx: CanvasRenderingContext2D,
  stroke: Stroke,
  from: number,
  to: number,
  open: boolean
) {
  ctx.beginPath();
  for (let i = Math.max(from, 0); i < to; i++) {
    const p = stroke[i];
    // A lone dot gets a little more ink than a taper would give it.
    const w =
      stroke.length === 1 && !open ? p.w * 0.8 : taperedWidth(stroke, i, open);
    if (i > 0) {
      const q = stroke[i - 1];
      const qw = taperedWidth(stroke, i - 1, open);
      const dx = p.x - q.x;
      const dy = p.y - q.y;
      const len = Math.hypot(dx, dy) || 1;
      const nx = -dy / len;
      const ny = dx / len;
      quad(ctx, [
        q.x + (nx * qw) / 2,
        q.y + (ny * qw) / 2,
        p.x + (nx * w) / 2,
        p.y + (ny * w) / 2,
        p.x - (nx * w) / 2,
        p.y - (ny * w) / 2,
        q.x - (nx * qw) / 2,
        q.y - (ny * qw) / 2,
      ]);
    }
    ctx.moveTo(p.x + w / 2, p.y);
    ctx.arc(p.x, p.y, w / 2, 0, Math.PI * 2);
  }
  ctx.fill();
}

/** The signature as standalone SVG, one filled outline per stroke. */
function toSvg(strokes: Stroke[], width: number, height: number) {
  const paths = strokes
    .map((stroke) => {
      if (stroke.length === 1) {
        const [p] = stroke;
        return `<circle cx="${p.x.toFixed(1)}" cy="${p.y.toFixed(1)}" r="${(p.w * 0.4).toFixed(2)}"/>`;
      }
      const left: string[] = [];
      const right: string[] = [];
      for (let i = 0; i < stroke.length; i++) {
        const p = stroke[i];
        const q = stroke[Math.max(i - 1, 0)];
        const r = stroke[Math.min(i + 1, stroke.length - 1)];
        const dx = r.x - q.x;
        const dy = r.y - q.y;
        const len = Math.hypot(dx, dy) || 1;
        const w = taperedWidth(stroke, i, false) / 2;
        left.push(
          `${(p.x - (dy / len) * w).toFixed(1)} ${(p.y + (dx / len) * w).toFixed(1)}`
        );
        right.push(
          `${(p.x + (dy / len) * w).toFixed(1)} ${(p.y - (dx / len) * w).toFixed(1)}`
        );
      }
      return `<path d="M${left.join("L")}L${right.reverse().join("L")}Z"/>`;
    })
    .join("");
  return `<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ${Math.round(width)} ${Math.round(height)}" fill="${INK}">${paths}</svg>`;
}

export interface SignaturePadProps {
  /** Called after each stroke, undo or clear, with the signature as SVG, or null once it's empty. */
  onChange?: (svg: string | null) => void;
  /** Accessible name of the drawing area. */
  label?: string;
  className?: string;
}

export default function SignaturePad({
  onChange,
  label = "Signature",
  className,
}: SignaturePadProps) {
  const wrapRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const [count, setCount] = useState(0);
  const [drawing, setDrawing] = useState(false);
  const [clearing, setClearing] = useState(false);

  const sim = useRef({
    strokes: [] as Stroke[],
    // Points of the current stroke already on the canvas.
    painted: 0,
    held: false,
    pressure: 0.5,
    usesPressure: false,
    targetX: 0,
    targetY: 0,
    x: 0,
    y: 0,
    vx: 0,
    vy: 0,
    width: MAX_WIDTH,
    raf: 0,
    last: 0,
    carry: 0,
    reduceMotion: false,
    size: { width: 0, height: 0 },
  });

  const latest = useRef({ onChange });
  latest.current = { onChange };

  const context = useCallback(() => {
    const ctx = canvasRef.current?.getContext("2d");
    if (ctx) {
      ctx.fillStyle = INK;
    }
    return ctx ?? null;
  }, []);

  /** Repaints every stroke, or only the first `fraction` of all the ink. */
  const redraw = useCallback(
    (fraction = 1) => {
      const ctx = context();
      const s = sim.current;
      if (!ctx) {
        return;
      }
      ctx.clearRect(0, 0, s.size.width, s.size.height);
      const total = s.strokes.reduce((sum, st) => sum + st.length, 0);
      let budget = Math.round(total * fraction);
      for (let k = 0; k < s.strokes.length && budget > 0; k++) {
        const stroke = s.strokes[k];
        const open = s.held && k === s.strokes.length - 1;
        paint(ctx, stroke, 0, Math.min(stroke.length, budget), open);
        budget -= stroke.length;
      }
    },
    [context]
  );

  const emit = useCallback(() => {
    const s = sim.current;
    setCount(s.strokes.length);
    latest.current.onChange?.(
      s.strokes.length ? toSvg(s.strokes, s.size.width, s.size.height) : null
    );
  }, []);

  // Size the canvas to its box at the screen's pixel density.
  useEffect(() => {
    const wrap = wrapRef.current;
    const canvas = canvasRef.current;
    if (!(wrap && canvas)) {
      return;
    }
    const s = sim.current;
    const fitCanvas = () => {
      const rect = wrap.getBoundingClientRect();
      const dpr = Math.min(window.devicePixelRatio || 1, 3);
      s.size = { width: rect.width, height: rect.height };
      canvas.width = Math.round(rect.width * dpr);
      canvas.height = Math.round(rect.height * dpr);
      canvas.getContext("2d")?.setTransform(dpr, 0, 0, dpr, 0, 0);
      redraw();
    };
    fitCanvas();
    const observer = new ResizeObserver(fitCanvas);
    observer.observe(wrap);
    const query = window.matchMedia("(prefers-reduced-motion: reduce)");
    s.reduceMotion = query.matches;
    const onMotion = () => {
      s.reduceMotion = query.matches;
    };
    query.addEventListener("change", onMotion);
    return () => {
      observer.disconnect();
      query.removeEventListener("change", onMotion);
      cancelAnimationFrame(s.raf);
      s.raf = 0;
    };
  }, [redraw]);

  // One step of the pen: the tip springs towards the pointer, and lays down
  // a point when it has travelled far enough, sized by its speed.
  const stepPen = useCallback(() => {
    const s = sim.current;
    const ax = (s.targetX - s.x) * TIP_STIFFNESS - s.vx * TIP_DAMPING;
    const ay = (s.targetY - s.y) * TIP_STIFFNESS - s.vy * TIP_DAMPING;
    s.vx += ax * STEP;
    s.vy += ay * STEP;
    s.x += s.vx * STEP;
    s.y += s.vy * STEP;
    const speed = Math.hypot(s.vx, s.vy);
    const pressure = s.usesPressure ? 0.45 + s.pressure * 0.9 : 1;
    const goal =
      (MAX_WIDTH -
        (MAX_WIDTH - MIN_WIDTH) * clamp(speed / SPEED_FOR_MIN, 0, 1)) *
      pressure;
    s.width += (goal - s.width) * WIDTH_EASE;
    const stroke = s.strokes.at(-1);
    const prev = stroke?.at(-1);
    if (stroke && prev && Math.hypot(s.x - prev.x, s.y - prev.y) >= MIN_GAP) {
      stroke.push({ x: s.x, y: s.y, w: s.width });
    }
    return speed;
  }, []);

  const tick = useCallback(
    (now: number) => {
      const s = sim.current;
      s.raf = 0;
      const elapsed = s.last ? Math.min((now - s.last) / 1000, 0.05) : STEP;
      s.last = now;
      s.carry += elapsed;
      let speed = 0;
      while (s.carry >= STEP) {
        speed = stepPen();
        s.carry -= STEP;
      }
      const ctx = context();
      const stroke = s.strokes.at(-1);
      if (ctx && stroke) {
        // Only the new ink; the point before it is repainted to join up.
        paint(ctx, stroke, s.painted - 1, stroke.length, true);
        s.painted = stroke.length;
      }
      const caughtUp =
        Math.hypot(s.targetX - s.x, s.targetY - s.y) < 0.3 && speed < 5;
      if (s.held || !caughtUp) {
        s.raf = requestAnimationFrame(tick);
        return;
      }
      // The pen has lifted and caught up: close the stroke with its tail
      // taper, and report the signature.
      s.last = 0;
      redraw();
      emit();
    },
    [context, emit, redraw, stepPen]
  );

  const localPoint = (event: PointerEvent) => {
    const rect = wrapRef.current?.getBoundingClientRect();
    return rect
      ? { x: event.clientX - rect.left, y: event.clientY - rect.top }
      : { x: 0, y: 0 };
  };

  const handlePointerDown = (event: PointerEvent<HTMLCanvasElement>) => {
    const s = sim.current;
    if (clearing || (event.pointerType === "mouse" && event.button !== 0)) {
      return;
    }
    event.preventDefault();
    event.currentTarget.setPointerCapture(event.pointerId);
    if (s.raf) {
      // Still settling the last stroke: finish it at once.
      cancelAnimationFrame(s.raf);
      s.raf = 0;
      s.last = 0;
      emit();
    }
    const p = localPoint(event);
    s.held = true;
    s.usesPressure = event.pointerType === "pen";
    s.pressure = event.pressure || 0.5;
    s.x = p.x;
    s.y = p.y;
    s.targetX = p.x;
    s.targetY = p.y;
    s.vx = 0;
    s.vy = 0;
    s.width = MAX_WIDTH;
    s.strokes.push([{ x: p.x, y: p.y, w: MAX_WIDTH }]);
    s.painted = 0;
    redraw();
    setDrawing(true);
    s.raf = requestAnimationFrame(tick);
  };

  const handlePointerMove = (event: PointerEvent<HTMLCanvasElement>) => {
    const s = sim.current;
    if (!s.held) {
      return;
    }
    const p = localPoint(event);
    s.targetX = p.x;
    s.targetY = p.y;
    if (s.usesPressure) {
      s.pressure = event.pressure;
    }
    if (s.reduceMotion) {
      // No trailing tip: the ink goes exactly where the pointer is.
      s.x = p.x;
      s.y = p.y;
      s.vx = 0;
      s.vy = 0;
    }
  };

  const handlePointerUp = () => {
    const s = sim.current;
    if (!s.held) {
      return;
    }
    s.held = false;
    setDrawing(false);
    if (!s.raf) {
      s.raf = requestAnimationFrame(tick);
    }
  };

  const undo = useCallback(() => {
    const s = sim.current;
    if (s.held || !s.strokes.length) {
      return;
    }
    s.strokes.pop();
    redraw();
    emit();
  }, [emit, redraw]);

  // The ink lifts off in the reverse of the order it went down.
  const clear = useCallback(() => {
    const s = sim.current;
    if (s.held || !s.strokes.length) {
      return;
    }
    const done = () => {
      s.strokes = [];
      redraw();
      setClearing(false);
      emit();
    };
    if (s.reduceMotion) {
      done();
      return;
    }
    setClearing(true);
    const start = performance.now();
    const frame = (now: number) => {
      const t = clamp((now - start) / CLEAR_MS, 0, 1);
      // ease-in-out, so the last strokes don't snap away.
      const eased = t < 0.5 ? 4 * t * t * t : 1 - (-2 * t + 2) ** 3 / 2;
      redraw(1 - eased);
      if (t < 1) {
        s.raf = requestAnimationFrame(frame);
      } else {
        s.raf = 0;
        done();
      }
    };
    s.raf = requestAnimationFrame(frame);
  }, [emit, redraw]);

  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    if (event.key === "z" && (event.metaKey || event.ctrlKey)) {
      event.preventDefault();
      undo();
    } else if (event.key === "Backspace" || event.key === "Delete") {
      event.preventDefault();
      clear();
    }
  };

  const empty = count === 0 && !drawing;

  return (
    // biome-ignore lint/a11y/noNoninteractiveElementInteractions: keyboard shortcuts for undo and clear while the pad has focus
    // biome-ignore lint/a11y/noStaticElementInteractions: as above
    <div
      className={cn(
        "w-full max-w-[380px] select-none overflow-hidden rounded-2xl border border-zinc-200 bg-white text-zinc-900 dark:border-zinc-800 dark:bg-zinc-950 dark:text-zinc-100",
        className
      )}
      onKeyDown={handleKeyDown}
    >
      <div className="relative h-[200px]" ref={wrapRef}>
        {/* The line to sign on. */}
        <div
          aria-hidden="true"
          className="pointer-events-none absolute inset-x-6 bottom-12 flex items-end gap-2 border-zinc-300 border-b pb-1.5 dark:border-zinc-700"
        >
          <span className="text-lg text-zinc-400 leading-none dark:text-zinc-600">
            ×
          </span>
          <span
            className={cn(
              "text-sm text-zinc-400 transition-[opacity,filter] duration-200 ease-out dark:text-zinc-600",
              empty ? "opacity-100 blur-0" : "opacity-0 blur-[2px]"
            )}
          >
            Sign here
          </span>
        </div>
        <canvas
          aria-label={`${label}${count ? `, ${count} stroke${count === 1 ? "" : "s"}` : ", empty"}`}
          className={cn(
            "absolute inset-0 h-full w-full touch-none dark:hue-rotate-180 dark:invert",
            "cursor-crosshair"
          )}
          onLostPointerCapture={handlePointerUp}
          onPointerCancel={handlePointerUp}
          onPointerDown={handlePointerDown}
          onPointerMove={handlePointerMove}
          onPointerUp={handlePointerUp}
          ref={canvasRef}
          role="img"
          tabIndex={0}
        />
      </div>
      <div className="flex items-center justify-between gap-3 border-zinc-200 border-t px-4 py-2.5 dark:border-zinc-800">
        <p aria-live="polite" className="truncate text-sm text-zinc-500">
          {count ? "Signed" : "Draw your signature"}
        </p>
        <div className="flex shrink-0 gap-1">
          <button
            className="rounded-md px-2.5 py-1 text-sm text-zinc-600 transition-colors duration-150 ease-out hover:bg-zinc-100 hover:text-zinc-900 focus-visible:outline-2 focus-visible:outline-zinc-400 disabled:pointer-events-none disabled:opacity-40 dark:text-zinc-400 dark:hover:bg-zinc-900 dark:hover:text-zinc-100"
            disabled={!count || clearing}
            onClick={undo}
            type="button"
          >
            Undo
          </button>
          <button
            className="rounded-md px-2.5 py-1 text-sm text-zinc-600 transition-colors duration-150 ease-out hover:bg-zinc-100 hover:text-zinc-900 focus-visible:outline-2 focus-visible:outline-zinc-400 disabled:pointer-events-none disabled:opacity-40 dark:text-zinc-400 dark:hover:bg-zinc-900 dark:hover:text-zinc-100"
            disabled={!count || clearing}
            onClick={clear}
            type="button"
          >
            Clear
          </button>
        </div>
      </div>
    </div>
  );
}
```


---

# Team Selector
> Animated team size selector with stacked overlapping avatars, spring transitions and increment controls. Built with React, Tailwind CSS and Motion.

Source: https://kokonutui.com/docs/inputs/team-selector

## Installation

```bash
npx shadcn@latest add @kokonutui/team-selector
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Team Selector
 * @version: 3.0.0
 * @date: 2026-04-23
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import { Minus, Plus } from "lucide-react";
import {
  AnimatePresence,
  MotionConfig,
  motion,
  useReducedMotion,
  type Variants,
} from "motion/react";
import Image from "next/image";
import { useEffect, useRef, useState } from "react";
import { cn } from "@/lib/utils";

const AVATAR_OVERLAP = 12;
const COUNTER_DISTANCE = 10;
const SHAKE_DURATION_MS = 280;
const EASE_OUT = [0.23, 1, 0.32, 1] as const;
const DICEBEAR_STYLE = "notionists-neutral";
const dicebearUrl = (seed: string) =>
  `https://api.dicebear.com/9.x/${DICEBEAR_STYLE}/svg?seed=${encodeURIComponent(seed)}&backgroundColor=f4f4f5,e4e4e7,d4d4d8,a1a1aa`;

export interface TeamMember {
  id: string;
  name: string;
  avatarUrl: string;
}

const DEFAULT_MEMBERS: TeamMember[] = [
  { id: "member-1", name: "Alex Rivera", avatarUrl: dicebearUrl("Alex") },
  { id: "member-2", name: "Blair Kim", avatarUrl: dicebearUrl("Blair") },
  { id: "member-3", name: "Casey Lin", avatarUrl: dicebearUrl("Casey") },
  { id: "member-4", name: "Devon Marsh", avatarUrl: dicebearUrl("Devon") },
];

const animations = {
  avatar: {
    visible: {
      opacity: 1,
      scale: 1,
      transition: {
        type: "spring",
        stiffness: 260,
        damping: 22,
        mass: 0.6,
      },
    },
    hidden: {
      opacity: 0,
      scale: 0.85,
      transition: { duration: 0.18, ease: EASE_OUT },
    },
  } satisfies Variants,
  vibration: {
    idle: { x: 0 },
    shake: {
      x: [-3, 3, -2, 2, 0] as const,
      transition: { duration: SHAKE_DURATION_MS / 1000, ease: EASE_OUT },
    },
  } satisfies Variants,
  // `custom` is the signed offset of the latest step. AnimatePresence hands
  // the current value to the leaving number too, so it always exits opposite
  // to the one coming in.
  counter: {
    enter: (offset: number) => ({ opacity: 0, y: offset }),
    center: {
      opacity: 1,
      y: 0,
      transition: { duration: 0.2, ease: EASE_OUT },
    },
    exit: (offset: number) => ({
      opacity: 0,
      y: -offset,
      transition: { duration: 0.12, ease: EASE_OUT },
    }),
  } satisfies Variants,
} as const;

const STEPPER_BUTTON_CLASS =
  "flex size-9 items-center justify-center rounded-xl border border-zinc-200/80 bg-white text-zinc-500 transition-[color,background-color,border-color,opacity,scale] duration-150 ease-[cubic-bezier(0.23,1,0.32,1)] hover:border-zinc-300 hover:bg-zinc-50 hover:text-zinc-900 focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-zinc-400/40 focus-visible:ring-offset-2 active:scale-[0.97] active:bg-zinc-100 aria-disabled:cursor-not-allowed aria-disabled:opacity-40 aria-disabled:hover:bg-white motion-reduce:active:scale-100 dark:border-white/8 dark:bg-zinc-900 dark:text-zinc-400 dark:active:bg-zinc-800/80 dark:focus-visible:ring-zinc-500/40 dark:focus-visible:ring-offset-zinc-900 dark:hover:border-white/16 dark:hover:bg-zinc-800 dark:hover:text-zinc-100 dark:aria-disabled:hover:bg-zinc-900";

interface TeamSelectorProps {
  members?: TeamMember[];
  defaultValue?: number;
  /** Controlled team size. Pair it with `onChange`. */
  value?: number;
  /** Smallest allowed team size. Defaults to 1. */
  min?: number;
  onChange?: (size: number) => void;
  label?: string;
  className?: string;
}

export default function TeamSelector({
  members = DEFAULT_MEMBERS,
  defaultValue = 1,
  value,
  min = 1,
  onChange,
  label = "Team Size",
  className,
}: TeamSelectorProps) {
  const maxTeamSize = members.length;
  const clampCount = (count: number) =>
    Math.min(Math.max(count, min), maxTeamSize);
  const [internalCount, setInternalCount] = useState(() =>
    clampCount(defaultValue)
  );
  const peopleCount = clampCount(value ?? internalCount);
  const [direction, setDirection] = useState<1 | -1>(1);
  // Direction follows every change, including a controlled `value` set from
  // outside (state adjusted during render, as React recommends).
  const [previousCount, setPreviousCount] = useState(peopleCount);
  if (peopleCount !== previousCount) {
    setPreviousCount(peopleCount);
    setDirection(peopleCount > previousCount ? 1 : -1);
  }
  const [isVibrating, setIsVibrating] = useState(false);
  const vibrationTimeoutRef = useRef<ReturnType<typeof setTimeout> | null>(
    null
  );
  const prefersReducedMotion = useReducedMotion();

  useEffect(
    () => () => {
      if (vibrationTimeoutRef.current) {
        clearTimeout(vibrationTimeoutRef.current);
      }
    },
    []
  );

  const triggerVibration = () => {
    if (prefersReducedMotion || vibrationTimeoutRef.current) {
      return;
    }
    setIsVibrating(true);
    vibrationTimeoutRef.current = setTimeout(() => {
      setIsVibrating(false);
      vibrationTimeoutRef.current = null;
    }, SHAKE_DURATION_MS);
  };

  const changeCount = (newCount: number) => {
    if (value === undefined) {
      setInternalCount(newCount);
    }
    onChange?.(newCount);
  };

  const handleIncrement = () => {
    if (peopleCount < maxTeamSize) {
      changeCount(peopleCount + 1);
    } else {
      triggerVibration();
    }
  };

  const handleDecrement = () => {
    if (peopleCount > min) {
      changeCount(peopleCount - 1);
    } else {
      triggerVibration();
    }
  };

  const counterOffset =
    direction * (prefersReducedMotion ? 0 : COUNTER_DISTANCE);
  const memberLabel = peopleCount === 1 ? "member" : "members";

  return (
    <div
      className={cn(
        "flex w-full flex-col items-center justify-center",
        className
      )}
    >
      <div className="w-full max-w-xs rounded-2xl border border-zinc-200/80 bg-white p-5 shadow-[0_1px_4px_rgba(0,0,0,0.04)] dark:border-white/8 dark:bg-zinc-900/60">
        <fieldset>
          <legend className="mb-5 w-full font-medium text-[11px] text-zinc-400 uppercase tracking-[0.14em] dark:text-zinc-500">
            {label}
          </legend>

          {/* Only the selected avatars render, so the row stays centred; the
              others slide over (layout) as one enters or leaves. Under reduced
              motion the avatars fade without scaling or sliding. */}
          <MotionConfig reducedMotion="user">
            <div className="mb-7 flex min-h-11 justify-center">
              <div className="flex items-center">
                <AnimatePresence initial={false}>
                  {members.slice(0, peopleCount).map((member, index) => (
                    <motion.div
                      animate="visible"
                      className="flex items-center justify-center"
                      exit="hidden"
                      initial="hidden"
                      key={member.id}
                      layout
                      style={{
                        marginLeft: index === 0 ? 0 : -AVATAR_OVERLAP,
                        zIndex: maxTeamSize - index,
                      }}
                      transition={{ layout: { duration: 0.2, ease: EASE_OUT } }}
                      variants={animations.avatar}
                    >
                      <Image
                        alt={member.name}
                        className="size-11 rounded-full border-2 border-white bg-zinc-100 object-cover shadow-[0_2px_8px_rgba(0,0,0,0.08)] ring-1 ring-black/5 dark:border-zinc-900 dark:bg-zinc-800 dark:ring-white/5"
                        height={88}
                        src={member.avatarUrl}
                        unoptimized
                        width={88}
                      />
                    </motion.div>
                  ))}
                </AnimatePresence>
              </div>
            </div>
          </MotionConfig>

          <motion.div
            animate={isVibrating ? "shake" : "idle"}
            className="flex items-center justify-center gap-5"
            initial="idle"
            variants={animations.vibration}
          >
            {/* aria-disabled rather than disabled: focus stays on the button at
                the bound and the click still reaches the shake feedback. */}
            <button
              aria-disabled={peopleCount <= min}
              aria-label="Decrease team size"
              className={STEPPER_BUTTON_CLASS}
              onClick={handleDecrement}
              type="button"
            >
              <Minus aria-hidden="true" className="size-3.5" strokeWidth={2} />
            </button>

            <output aria-live="polite" className="sr-only">
              {peopleCount} {memberLabel}
            </output>
            <div
              aria-hidden="true"
              className="flex min-w-16 flex-col items-center"
            >
              <div className="relative h-9 overflow-hidden">
                <AnimatePresence
                  custom={counterOffset}
                  initial={false}
                  mode="popLayout"
                >
                  <motion.span
                    animate="center"
                    className="block select-none font-semibold text-3xl text-zinc-900 tabular-nums dark:text-zinc-100"
                    custom={counterOffset}
                    exit="exit"
                    initial="enter"
                    key={peopleCount}
                    variants={animations.counter}
                  >
                    {peopleCount}
                  </motion.span>
                </AnimatePresence>
              </div>
              <span className="text-[11px] text-zinc-400 dark:text-zinc-500">
                {memberLabel}
              </span>
            </div>

            <button
              aria-disabled={peopleCount >= maxTeamSize}
              aria-label="Increase team size"
              className={STEPPER_BUTTON_CLASS}
              onClick={handleIncrement}
              type="button"
            >
              <Plus aria-hidden="true" className="size-3.5" strokeWidth={2} />
            </button>
          </motion.div>
        </fieldset>
      </div>
    </div>
  );
}
```


---

# Wheel Picker
> iOS-style 3D drum picker with flick momentum, built with React and Motion.

Source: https://kokonutui.com/docs/inputs/wheel-picker

## Installation

```bash
npx shadcn@latest add @kokonutui/wheel-picker
```

## Source

```tsx
"use client";

/**
 * @author: @dorianbaffier
 * @description: Wheel Picker
 * @version: 1.0.0
 * @date: 2026-10-13
 * @license: MIT
 * @website: https://kokonutui.com
 * @github: https://github.com/kokonut-labs/kokonutui
 */

import {
  type AnimationPlaybackControls,
  animate,
  type MotionValue,
  motion,
  useMotionValue,
  useMotionValueEvent,
  useReducedMotion,
  useTransform,
} from "motion/react";
import {
  type KeyboardEvent,
  type PointerEvent,
  useEffect,
  useRef,
  useState,
} from "react";
import { cn } from "@/lib/utils";

export interface WheelOption {
  value: string;
  label: string;
}

export interface WheelColumn {
  id: string;
  /** Accessible name of the column, e.g. "Hours". */
  label: string;
  options: WheelOption[];
  /** Wrap around from the last option to the first. */
  loop?: boolean;
  /** Tailwind width class for the column. */
  className?: string;
}

const range = (count: number, format: (i: number) => string) =>
  Array.from({ length: count }, (_, i) => ({
    value: String(i),
    label: format(i),
  }));

const DEFAULT_COLUMNS: WheelColumn[] = [
  {
    id: "hour",
    label: "Hours",
    loop: true,
    className: "w-16",
    options: range(12, (i) => String(i + 1)),
  },
  {
    id: "minute",
    label: "Minutes",
    loop: true,
    className: "w-16",
    options: range(60, (i) => String(i).padStart(2, "0")),
  },
  {
    id: "period",
    label: "AM or PM",
    className: "w-16",
    options: [
      { value: "am", label: "AM" },
      { value: "pm", label: "PM" },
    ],
  },
];

const DEFAULT_VALUE: Record<string, string> = {
  hour: "8",
  minute: "41",
  period: "am",
};

const ITEM_HEIGHT = 36;
// Each row sits this many degrees further round the drum.
const ITEM_ANGLE = 20;
// Drum radius that makes neighbouring rows touch exactly.
// Rounded so server and browser trig can't disagree in the markup.
const RADIUS =
  Math.round(
    (ITEM_HEIGHT / 2 / Math.tan((ITEM_ANGLE / 2) * (Math.PI / 180))) * 100
  ) / 100;
// Rows past ±90° face away; render a few either side of that and no more.
const WINDOW = Math.ceil(90 / ITEM_ANGLE);
const VIEW_HEIGHT = Math.round(RADIUS * 2) + ITEM_HEIGHT / 2;
// A non-looping wheel can be dragged this many rows past either end.
const MAX_OVERSCROLL = 1.2;
const VELOCITY_WINDOW_MS = 80;
const TAP_SLOP = 4;
// Seconds of travel a flick is worth: release speed × COAST = rows coasted.
const COAST = 0.32;

const mod = (n: number, m: number) => ((n % m) + m) % m;

function damp(distance: number, max: number) {
  return max * (1 - Math.exp(-distance / max));
}

function hapticTick() {
  if (typeof navigator !== "undefined" && "vibrate" in navigator) {
    navigator.vibrate(1);
  }
}

export interface WheelPickerProps {
  columns?: WheelColumn[];
  /** Controlled selection, keyed by column id. */
  value?: Record<string, string>;
  /** Initial selection when uncontrolled. */
  defaultValue?: Record<string, string>;
  /** Called once a wheel comes to rest on a new option. */
  onValueChange?: (value: Record<string, string>) => void;
  /** Accessible name for the whole picker. */
  label?: string;
  className?: string;
}

/**
 * An iOS-style drum picker. Each column is a real 3D cylinder: rows are
 * placed round it with `rotateX() translateZ()` and the whole drum turns
 * with a single transform, so a frame costs one style write per column.
 *
 * The drum is drawn twice. The bottom copy is muted; the top copy is in full
 * color and clipped to the selection band. Text turns dark exactly as it
 * crosses the band's edge, the way the native picker does.
 */
export default function WheelPicker({
  columns = DEFAULT_COLUMNS,
  value: valueProp,
  defaultValue = DEFAULT_VALUE,
  onValueChange,
  label = "Time",
  className,
}: WheelPickerProps) {
  const [internal, setInternal] = useState(defaultValue);
  const value = valueProp ?? internal;

  const select = (columnId: string, optionValue: string) => {
    if (value[columnId] === optionValue) {
      return;
    }
    const next = { ...value, [columnId]: optionValue };
    if (valueProp === undefined) {
      setInternal(next);
    }
    onValueChange?.(next);
  };

  return (
    // biome-ignore lint/a11y/useSemanticElements: a fieldset would add a border and legend layout the picker doesn't want.
    <div
      aria-label={label}
      className={cn(
        "relative flex select-none justify-center rounded-2xl border border-zinc-200 bg-white px-3 dark:border-zinc-800 dark:bg-zinc-950",
        className
      )}
      role="group"
    >
      {/* The selection band, shared by every column. */}
      <div
        aria-hidden="true"
        className="pointer-events-none absolute inset-x-2 top-1/2 -translate-y-1/2 rounded-lg bg-zinc-100 dark:bg-zinc-800/70"
        style={{ height: ITEM_HEIGHT }}
      />
      {columns.map((column) => (
        <WheelColumnView
          column={column}
          key={column.id}
          onSelect={(optionValue) => select(column.id, optionValue)}
          selected={value[column.id]}
        />
      ))}
    </div>
  );
}

function WheelColumnView({
  column,
  selected,
  onSelect,
}: {
  column: WheelColumn;
  selected: string | undefined;
  onSelect: (value: string) => void;
}) {
  const { options, loop = false } = column;
  const count = options.length;
  const selectedIndex = Math.max(
    options.findIndex((option) => option.value === selected),
    0
  );
  const reduceMotion = useReducedMotion();

  // Position on the drum in rows. A looping wheel uses an unbounded
  // "virtual" index so it can spin forever; the option is index mod count.
  const position = useMotionValue(selectedIndex);
  const [center, setCenter] = useState(selectedIndex);
  const animation = useRef<AnimationPlaybackControls | null>(null);
  const pointerType = useRef("mouse");
  const drag = useRef<{
    id: number;
    startY: number;
    startPosition: number;
    moved: boolean;
    samples: { t: number; v: number }[];
  } | null>(null);
  const columnRef = useRef<HTMLDivElement>(null);

  const drum = useTransform(
    position,
    (p) => `translateZ(${-RADIUS}px) rotateX(${p * ITEM_ANGLE}deg)`
  );

  const optionAt = (index: number) => options[mod(index, count)];

  useMotionValueEvent(position, "change", (p) => {
    const rounded = Math.round(p);
    if (rounded !== center) {
      setCenter(rounded);
      if (pointerType.current === "touch") {
        hapticTick();
      }
    }
  });

  // Follow the selection when it changes from outside (controlled value,
  // keyboard, another column re-rendering the parent).
  useEffect(() => {
    if (drag.current || animation.current) {
      return;
    }
    const current = mod(Math.round(position.get()), count);
    if (current === selectedIndex) {
      return;
    }
    // Take the short way round on a looping wheel.
    let delta = selectedIndex - current;
    if (loop && Math.abs(delta) > count / 2) {
      delta -= Math.sign(delta) * count;
    }
    position.jump(Math.round(position.get()) + delta);
  }, [selectedIndex, count, loop, position]);

  useEffect(() => () => animation.current?.stop(), []);

  const settle = () => {
    animation.current = null;
    onSelect(optionAt(Math.round(position.get())).value);
  };

  const clampIndex = (index: number) =>
    loop ? index : Math.min(Math.max(index, 0), count - 1);

  const goTo = (target: number) => {
    animation.current?.stop();
    animation.current = null;
    if (reduceMotion) {
      position.jump(target);
      settle();
      return;
    }
    animation.current = animate(position, target, {
      type: "spring",
      duration: 0.4,
      bounce: 0.15,
      restDelta: 0.001,
      onComplete: settle,
    });
  };

  // Past the ends of a non-looping wheel the drum keeps following the
  // finger, but less and less, then springs back on release.
  const withOverscroll = (raw: number) => {
    if (loop) {
      return raw;
    }
    if (raw < 0) {
      return -damp(-raw, MAX_OVERSCROLL);
    }
    if (raw > count - 1) {
      return count - 1 + damp(raw - (count - 1), MAX_OVERSCROLL);
    }
    return raw;
  };

  const handlePointerDown = (event: PointerEvent<HTMLDivElement>) => {
    if (drag.current) {
      return;
    }
    if (event.pointerType === "mouse" && event.button !== 0) {
      return;
    }
    animation.current?.stop();
    animation.current = null;
    pointerType.current = event.pointerType;
    event.currentTarget.setPointerCapture(event.pointerId);
    drag.current = {
      id: event.pointerId,
      startY: event.clientY,
      startPosition: position.get(),
      moved: false,
      samples: [{ t: event.timeStamp, v: position.get() }],
    };
  };

  const handlePointerMove = (event: PointerEvent<HTMLDivElement>) => {
    const current = drag.current;
    if (!current || current.id !== event.pointerId) {
      return;
    }
    const dy = event.clientY - current.startY;
    if (!current.moved && Math.abs(dy) < TAP_SLOP) {
      return;
    }
    current.moved = true;
    const raw = current.startPosition - dy / ITEM_HEIGHT;
    position.set(withOverscroll(raw));
    current.samples.push({ t: event.timeStamp, v: raw });
    while (
      current.samples.length > 2 &&
      event.timeStamp - current.samples[0].t > VELOCITY_WINDOW_MS
    ) {
      current.samples.shift();
    }
  };

  const handlePointerUp = (event: PointerEvent<HTMLDivElement>) => {
    const current = drag.current;
    if (!current || current.id !== event.pointerId) {
      return;
    }
    drag.current = null;

    if (!current.moved) {
      // A tap: turn to the row under the finger. asin undoes the drum's
      // foreshortening, so rows near the edges are hit accurately too.
      const rect = event.currentTarget.getBoundingClientRect();
      const offsetY = event.clientY - (rect.top + rect.height / 2);
      const ratio = Math.max(-1, Math.min(1, offsetY / RADIUS));
      const rows = Math.round((Math.asin(ratio) * 180) / Math.PI / ITEM_ANGLE);
      goTo(clampIndex(Math.round(position.get()) + rows));
      return;
    }

    const first = current.samples[0];
    const last = current.samples.at(-1) ?? first;
    const elapsed = (last.t - first.t) / 1000;
    // Holding still before letting go is a placement, not a flick.
    const paused = event.timeStamp - last.t > VELOCITY_WINDOW_MS;
    const velocity = elapsed > 0 && !paused ? (last.v - first.v) / elapsed : 0;
    const p = position.get();
    const outOfBounds = !loop && (p < 0 || p > count - 1);

    if (reduceMotion || outOfBounds || Math.abs(velocity) < 2) {
      goTo(clampIndex(Math.round(p)));
      return;
    }
    // A flick spins the drum, slows down, and lands exactly on a row. On a
    // non-looping wheel it bounces off the end if it runs out of options.
    animation.current?.stop();
    // Project where the flick would coast to, land that on a whole row,
    // then spring there carrying the release velocity. Critically damped, so
    // it decelerates smoothly; past a non-looping end it overshoots slightly
    // and settles back, which reads as a bounce.
    const target = clampIndex(Math.round(p + velocity * COAST));
    animation.current = animate(position, target, {
      type: "spring",
      velocity,
      stiffness: 140,
      damping: 24,
      restDelta: 0.005,
      onComplete: settle,
    });
  };

  // Keyboard steps are instant: they repeat quickly, and a spin per press
  // would always be a step behind.
  const handleKeyDown = (event: KeyboardEvent<HTMLDivElement>) => {
    const index = Math.round(position.get());
    const moves: Record<string, number> = {
      ArrowUp: 1,
      ArrowDown: -1,
      PageUp: 5,
      PageDown: -5,
    };
    let target: number;
    if (event.key === "Home") {
      target = index - mod(index, count);
    } else if (event.key === "End") {
      target = index - mod(index, count) + count - 1;
    } else if (event.key in moves) {
      target = clampIndex(index + moves[event.key]);
    } else {
      return;
    }
    event.preventDefault();
    animation.current?.stop();
    pointerType.current = "keyboard";
    position.jump(target);
    settle();
  };

  // Wheel and trackpad scrolling turn the drum, then it settles on the
  // nearest row once the scrolling stops. The listener is attached once and
  // reads the latest props through a ref, so a re-render mid-scroll (the
  // drum crossing a row) can't drop the pending settle.
  const wheel = useRef({ loop, count, goTo, clampIndex });
  wheel.current = { loop, count, goTo, clampIndex };
  useEffect(() => {
    const node = columnRef.current;
    if (!node) {
      return;
    }
    let timer: number | undefined;
    const onWheel = (event: WheelEvent) => {
      event.preventDefault();
      const latest = wheel.current;
      animation.current?.stop();
      animation.current = null;
      pointerType.current = "mouse";
      const raw = position.get() + (event.deltaY / ITEM_HEIGHT) * 0.4;
      position.set(
        latest.loop
          ? raw
          : Math.min(Math.max(raw, -0.4), latest.count - 1 + 0.4)
      );
      window.clearTimeout(timer);
      timer = window.setTimeout(() => {
        const settled = wheel.current;
        settled.goTo(settled.clampIndex(Math.round(position.get())));
      }, 120);
    };
    node.addEventListener("wheel", onWheel, { passive: false });
    return () => {
      node.removeEventListener("wheel", onWheel);
      window.clearTimeout(timer);
    };
  }, [position]);

  const rows: number[] = [];
  for (let i = center - WINDOW; i <= center + WINDOW; i++) {
    if (loop || (i >= 0 && i < count)) {
      rows.push(i);
    }
  }

  return (
    <div
      aria-label={column.label}
      aria-valuemax={count - 1}
      aria-valuemin={0}
      aria-valuenow={selectedIndex}
      aria-valuetext={options[selectedIndex]?.label}
      className={cn(
        "relative cursor-grab touch-none rounded-lg outline-none active:cursor-grabbing",
        "focus-visible:ring-2 focus-visible:ring-zinc-400 focus-visible:ring-inset",
        column.className ?? "w-16"
      )}
      onKeyDown={handleKeyDown}
      onLostPointerCapture={handlePointerUp}
      onPointerCancel={handlePointerUp}
      onPointerDown={handlePointerDown}
      onPointerMove={handlePointerMove}
      onPointerUp={handlePointerUp}
      ref={columnRef}
      role="spinbutton"
      style={{ height: VIEW_HEIGHT }}
      tabIndex={0}
    >
      {/* The fade sits on an inner layer so the focus ring stays crisp. */}
      <div
        className="absolute inset-0"
        style={{
          maskImage:
            "linear-gradient(to bottom, transparent, #000 34%, #000 66%, transparent)",
        }}
      >
        <Drum
          drum={drum}
          optionAt={optionAt}
          rowClassName="text-zinc-400 dark:text-zinc-500"
          rows={rows}
        />
        <Drum
          clip
          drum={drum}
          optionAt={optionAt}
          rowClassName="font-medium text-zinc-900 dark:text-zinc-50"
          rows={rows}
        />
      </div>
    </div>
  );
}

function Drum({
  drum,
  rows,
  optionAt,
  rowClassName,
  clip = false,
}: {
  drum: MotionValue<string>;
  rows: number[];
  optionAt: (index: number) => WheelOption;
  rowClassName: string;
  clip?: boolean;
}) {
  return (
    <div
      aria-hidden="true"
      className="pointer-events-none absolute inset-0"
      style={{
        perspective: 1000,
        clipPath: clip
          ? `inset(calc(50% - ${ITEM_HEIGHT / 2}px) 0 calc(50% - ${ITEM_HEIGHT / 2}px) 0)`
          : undefined,
      }}
    >
      <motion.div
        className="absolute inset-x-0 top-1/2"
        style={{ transform: drum, transformStyle: "preserve-3d" }}
      >
        {rows.map((index) => (
          <div
            className={cn(
              "absolute inset-x-0 flex items-center justify-center text-xl tabular-nums [backface-visibility:hidden]",
              rowClassName
            )}
            key={index}
            style={{
              top: -ITEM_HEIGHT / 2,
              height: ITEM_HEIGHT,
              transform: `rotateX(${-index * ITEM_ANGLE}deg) translateZ(${RADIUS}px)`,
            }}
          >
            {optionAt(index).label}
          </div>
        ))}
      </motion.div>
    </div>
  );
}
```