feat: add multiline text plugin with auto-expand editor

Features:
- Multiline text display with word wrapping
- Contenteditable-based editor for multiline editing
- Auto-expand editor height based on content
- Keyboard shortcuts (Shift+Enter for newline, Enter to save, Esc to cancel)
- Text normalization (trim whitespace, normalize line endings)

Implementation:
- Created src/plugins/jsmind.multiline-text.js plugin
- Added createMultilineRender() function for custom node rendering
- Overrode edit_node_begin/end for contenteditable editor
- Editor matches node dimensions with no border
- Auto-expands height on input without scrollbar

Configuration:
- text_width: Maximum width for multiline text nodes (default: 200)
- line_height: Line height for text (default: '1.5')

Documentation:
- Added English documentation (docs/en/plugin-multiline-text.md)
- Added Chinese documentation (docs/zh/plugin-multiline-text.md)
- Integrated plugin into example/demo.html

Build:
- Added plugin to rollup.config.js
- Fixed external dependency to prevent bundling jsMind core
- Generated UMD build (es6/jsmind.multiline-text.js)

Breaking Changes:
- Removed standalone multiline-text-demo.html (integrated into demo.html)
- Removed .d.ts file (using JSDoc instead)

Author: UmbraCi

.config/rollup.config.js

@@ -73,4 +73,29 @@ export default [
             }),
         ],
     },
+    {
+        input: 'src/plugins/jsmind.multiline-text.js',
+        output: {
+            name: 'jsMindMultilineText',
+            file: 'es6/jsmind.multiline-text.js',
+            format: 'umd',
+            banner: '/**\n* @license BSD-3-Clause\n* @copyright 2014-2025 [email protected]\n*\n* Project Home:\n*   https://github.com/hizzgdev/jsmind/\n*/',
+            sourcemap: true,
+            globals: {
+                jsmind: 'jsMind',
+            },
+            exports: 'named',
+        },
+        external: ['jsmind'],
+        plugins: [
+            cleanup({
+                comments: 'none',
+            }),
+            terser({
+                output: {
+                    comments: 'all',
+                },
+            }),
+        ],
+    },
 ];

docs/en/plugin-multiline-text.md

@@ -0,0 +1,315 @@
+# Multiline Text Plugin
+
+The Multiline Text Plugin provides complete multiline text support for jsMind, including display and editing capabilities.
+
+## Features
+
+- ✅ **Multiline Text Display**: Display multiline text in nodes
+- ✅ **Multiline Text Editing**: Rich text editor using `contentEditable`
+- ✅ **Auto Word Wrap**: Automatic line wrapping when text exceeds maximum width
+- ✅ **Auto Height Expansion**: Editor height automatically adjusts to content
+- ✅ **Keyboard Shortcuts**:
+  - `Shift + Enter`: Insert line break
+  - `Enter`: Save changes
+  - `Esc`: Cancel editing
+  - `Tab`: Save changes
+- ✅ **Text Normalization**: Automatically trim whitespace, normalize line endings, limit consecutive blank lines
+
+## Installation
+
+### Method 1: UMD (Browser)
+
+```html
+<script src="es6/jsmind.js"></script>
+<script src="es6/jsmind.multiline-text.js"></script>
+```
+
+### Method 2: ES6 Module
+
+```javascript
+import jsMind from './es6/jsmind.js';
+import { createMultilineRender } from './es6/jsmind.multiline-text.js';
+```
+
+## Usage
+
+### Basic Usage
+
+```javascript
+// UMD (Browser)
+const options = {
+    container: 'jsmind_container',
+    editable: true,
+    view: {
+        // Use the custom render function provided by the plugin
+        custom_node_render: jsMindMultilineText.createMultilineRender({
+            text_width: 200,
+            line_height: '1.5',
+        })
+    },
+    plugin: {
+        multiline_text: {
+            text_width: 200,
+            line_height: '1.5',
+        }
+    }
+};
+
+const jm = new jsMind(options);
+jm.show(mind_data);
+```
+
+### ES6 Module Usage
+
+```javascript
+import jsMind from './es6/jsmind.js';
+import { createMultilineRender } from './es6/jsmind.multiline-text.js';
+
+const options = {
+    container: 'jsmind_container',
+    editable: true,
+    view: {
+        custom_node_render: createMultilineRender({
+            text_width: 200,
+            line_height: '1.5',
+        })
+    },
+    plugin: {
+        multiline_text: {
+            text_width: 200,
+            line_height: '1.5',
+        }
+    }
+};
+
+const jm = new jsMind(options);
+jm.show(mind_data);
+```
+
+## Configuration Options
+
+### `createMultilineRender(options)`
+
+Create a custom node render function for multiline text.
+
+**Parameters:**
+
+| Option | Type | Default | Description |
+|--------|------|---------|-------------|
+| `text_width` | `number` | `200` | Maximum width for multiline text nodes (px) |
+| `line_height` | `string` | `'1.5'` | Line height for text |
+
+**Returns:** `function(jsMind, HTMLElement, Node): boolean`
+
+**Example:**
+
+```javascript
+const customRender = createMultilineRender({
+    text_width: 250,
+    line_height: '1.6',
+});
+```
+
+### Plugin Options
+
+Configure the plugin behavior in `options.plugin.multiline_text`:
+
+```javascript
+{
+    plugin: {
+        multiline_text: {
+            text_width: 200,      // Maximum width for multiline text
+            line_height: '1.5',   // Line height
+        }
+    }
+}
+```
+
+## How It Works
+
+### 1. Node Rendering
+
+The plugin provides a custom render function that:
+
+1. Detects if node topic contains newline characters (`\n`)
+2. If yes, applies multiline styles:
+   - `white-space: pre-wrap` - Preserve line breaks and spaces
+   - `word-break: break-word` - Break long words
+   - `max-width: {text_width}px` - Limit maximum width
+3. If no, uses default rendering
+
+### 2. Node Editing
+
+When editing a node, the plugin:
+
+1. Creates a `<div contenteditable="plaintext-only">` editor
+2. Sets editor styles to match the node element:
+   - Width = node width
+   - Min-height = node height
+   - Auto-expands height based on content
+3. Handles keyboard events:
+   - `Shift + Enter`: Insert line break
+   - `Enter`: Save changes
+   - `Esc`: Cancel editing
+   - `Tab`: Save changes
+4. Auto-expands height on input
+5. Saves changes on blur (with 100ms delay)
+
+### 3. Text Normalization
+
+When saving, the plugin normalizes the text:
+
+```javascript
+const topic = (editor.textContent || '')
+    .trim()                      // Remove leading/trailing whitespace
+    .replace(/\r\n/g, '\n')      // Normalize Windows line endings
+    .replace(/\r/g, '\n')        // Normalize Mac line endings
+    .replace(/\n{3,}/g, '\n\n'); // Limit consecutive blank lines to 2
+```
+
+## Examples
+
+### Example 1: Basic Multiline Text
+
+```javascript
+const mind = {
+    meta: { name: 'Demo', author: 'jsMind', version: '1.0' },
+    format: 'node_tree',
+    data: {
+        id: 'root',
+        topic: 'Multiline Text\nMind Map',
+        children: [
+            {
+                id: 'node1',
+                topic: 'Line 1\nLine 2\nLine 3',
+            },
+        ],
+    },
+};
+
+jm.show(mind);
+```
+
+### Example 2: Programmatically Add Multiline Node
+
+```javascript
+// Add a multiline child node
+jm.add_node(
+    'parent_node_id',
+    'new_node_id',
+    'First line\nSecond line\nThird line'
+);
+```
+
+### Example 3: Update Node to Multiline
+
+```javascript
+// Update existing node to multiline text
+jm.update_node('node_id', 'New line 1\nNew line 2');
+```
+
+## Editor Behavior
+
+### Auto Height Expansion
+
+The editor automatically expands its height based on content:
+
+```javascript
+const autoExpand = () => {
+    editor.style.height = 'auto';
+    editor.style.height = editor.scrollHeight + 'px';
+};
+$.on(editor, 'input', autoExpand);
+setTimeout(autoExpand, 0);  // Initial expand
+```
+
+**Behavior:**
+- Initial height = node height
+- Expands when content exceeds initial height
+- Shrinks when content is deleted (but not below initial height)
+- No scrollbar (overflow: hidden)
+
+### Editor Styles
+
+```css
+.jsmind-multiline-editor {
+    width: {node.clientWidth}px;
+    min-height: {node.clientHeight}px;
+    line-height: {opts.line_height};
+    border: none;
+    outline: none;
+    white-space: pre-wrap;
+    word-break: break-word;
+    box-sizing: border-box;
+    overflow: hidden;
+}
+```
+
+## API Reference
+
+### `createMultilineRender(options)`
+
+Create a custom node render function.
+
+**Type:**
+```typescript
+function createMultilineRender(options?: {
+    text_width?: number;
+    line_height?: string;
+}): (jm: jsMind, element: HTMLElement, node: Node) => boolean
+```
+
+**Example:**
+```javascript
+const render = createMultilineRender({
+    text_width: 250,
+    line_height: '1.6',
+});
+```
+
+## Browser Compatibility
+
+- ✅ Chrome 60+
+- ✅ Firefox 55+
+- ✅ Safari 11+
+- ✅ Edge 79+
+
+**Note:** Requires `contenteditable="plaintext-only"` support.
+
+## Troubleshooting
+
+### Issue: Plugin not working
+
+**Solution:**
+1. Make sure the plugin script is loaded after jsMind core
+2. Check that `custom_node_render` is set in options
+3. Check that `plugin.multiline_text` is configured
+4. Open browser console and look for `[Multiline Plugin] Initializing...`
+
+### Issue: Editor not showing
+
+**Solution:**
+1. Check that the node is editable (`options.editable = true`)
+2. Check browser console for errors
+3. Verify that `contenteditable` is supported in your browser
+
+### Issue: Height not expanding
+
+**Solution:**
+1. Check that `overflow: hidden` is set on the editor
+2. Verify that the `input` event is firing
+3. Check browser console for JavaScript errors
+
+## License
+
+BSD-3-Clause
+
+## Author
+
+UmbraCi
+
+## Links
+
+- [GitHub Repository](https://github.com/hizzgdev/jsmind/)
+- [Documentation](https://hizzgdev.github.io/jsmind/)
+