# ScrollArea Hook

JavaScript hook for custom styled scrollbars with draggable thumb support.

## Hook Name

```javascript
ScrollArea
```

## Used By Components

- `scroll_area`

## Features

- **Custom Scrollbars**: Replace native scrollbars with styled versions
- **Vertical Scrolling**: Custom vertical scrollbar
- **Horizontal Scrolling**: Custom horizontal scrollbar
- **Draggable Thumbs**: Click and drag to scroll
- **Scroll Sync**: Thumb position syncs with content
- **Auto-hide**: Optional auto-hiding scrollbars
- **Keyboard Support**: Focus and keyboard scroll

## Element Structure

The hook expects this DOM structure:

```html
<div id="scroll-1" phx-hook="ScrollArea" class="scroll-area-wrapper">
  <!-- Scrollable viewport -->
  <div class="scroll-viewport">
    <div class="scroll-content">
      <!-- Your content here -->
    </div>
  </div>

  <!-- Vertical scrollbar -->
  <div class="scrollbar-y">
    <div class="thumb-y"></div>
  </div>

  <!-- Horizontal scrollbar -->
  <div class="scrollbar-x">
    <div class="thumb-x"></div>
  </div>
</div>
```

## `<.scroll_area>` Attributes Seen in Examples

| Attribute | Example values | Notes |
|---|---|---|
| `id` | any string | required |
| `height` | `h-64`, `h-96`, `h-48`, `h-[400px]`, `h-[500px]`, `h-[600px]` | Tailwind height class |
| `width` | `w-64`, `w-48` | Tailwind width class |
| `horizontal` | `true` / `false` | enable horizontal scrollbar |
| `vertical` | `true` / `false` | enable vertical scrollbar |
| `scrollbar_width` | `w-1` | Tailwind width class for thumb thickness |
| `type` | `"hover"` | auto-hide scrollbars, shown on hover |
| `padding` | `"medium"`, `"large"` | inner content padding |
| `content_class` | e.g. `space-y-4` | extra classes on `.scroll-content` |
| `class` | any | classes on the wrapper |

## Usage Examples

### Basic / Fixed Height & Width

```heex
<.scroll_area id="content-scroll" height="h-64">
  <p>Long scrollable content here...</p>
</.scroll_area>

<.scroll_area id="sidebar-scroll" height="h-[400px]" width="w-64">
  <nav>
    <a :for={item <- @nav_items} href={item.url} class="block p-2">
      {item.label}
    </a>
  </nav>
</.scroll_area>
```

### Both Scrollbars / Horizontal Only

```heex
<.scroll_area id="code-scroll" height="h-96" horizontal={true} vertical={true}>
  <pre><code>{@code_content}</code></pre>
</.scroll_area>

<.scroll_area id="horizontal-scroll" horizontal={true} vertical={false} class="w-full">
  <div class="flex gap-4 w-max">
    <.card :for={item <- @items} class="w-64 shrink-0">
      {item.title}
    </.card>
  </div>
</.scroll_area>
```

### Custom Scrollbar Width & Auto-hide

```heex
<.scroll_area id="thin-scroll" height="h-48" scrollbar_width="w-1">
  <p>Content with thin scrollbar...</p>
</.scroll_area>

<.scroll_area id="auto-scroll" height="h-64" type="hover">
  <p>Scrollbars appear on hover...</p>
</.scroll_area>
```

### Padding & Content Class (Chat Messages)

```heex
<.scroll_area
  id="chat-messages"
  height="h-[500px]"
  class="border rounded-lg"
  padding="medium"
  content_class="space-y-4"
>
  <div :for={message <- @messages} class="mb-4">
    <div class="font-medium">{message.sender}</div>
    <div class="text-gray-600">{message.content}</div>
  </div>
</.scroll_area>
```

### Code Editor Panel (Multiple Scroll Areas)

```heex
<div class="flex gap-4">
  <.scroll_area id="file-tree" height="h-[600px]" width="w-48">
    <div :for={file <- @files} class="py-1 px-2 hover:bg-gray-100">
      {file.name}
    </div>
  </.scroll_area>

  <.scroll_area id="code-panel" height="h-[600px]" class="flex-1" horizontal={true}>
    <pre class="text-sm"><code>{@file_content}</code></pre>
  </.scroll_area>
</div>
```

## CSS Classes

| Class | Description |
|-------|-------------|
| `.scroll-area-wrapper` | Main container |
| `.scroll-viewport` | Scrollable area |
| `.scroll-content` | Inner content wrapper |
| `.scrollbar-y` | Vertical scrollbar track |
| `.scrollbar-x` | Horizontal scrollbar track |
| `.thumb-y` | Vertical scrollbar thumb |
| `.thumb-x` | Horizontal scrollbar thumb |

## Scrollbar Visibility

Native scrollbars are hidden:

```css
.scroll-viewport {
  scrollbar-width: none; /* Firefox */
}
.scroll-viewport::-webkit-scrollbar {
  display: none; /* Chrome, Safari */
}
```

## Thumb Behavior

- **Click track**: Scroll to position
- **Drag thumb**: Smooth scroll
- **Wheel scroll**: Updates thumb position
- **Keyboard**: Arrow keys when focused

## JavaScript Integration

Register the hook in your `app.js`:

```javascript
import ScrollArea from "./scrollArea"

let liveSocket = new LiveSocket("/live", Socket, {
  hooks: { ScrollArea }
})
```