Use the breadcrumb as the draggable handle

docs/reference/deprecated.md

@@ -7,6 +7,7 @@ Gutenberg's deprecation policy is intended to support backwards-compatibility fo
 
 ## 3.7.0
 
+ - `wp.components.Draggable` has been deprecated. Please, use `wp.components.withDraggable` instead.
  - `wp.components.withAPIData` has been removed. Please use the Core Data module or `wp.apiFetch` directly instead.
  - `wp.data.dispatch("core").receiveTerms` has been deprecated. Please use `wp.data.dispatch("core").receiveEntityRecords` instead.
  - `getCategories` resolvers has been deprecated. Please use `getEntityRecords` resolver instead.

edit-post/assets/stylesheets/_z-index.scss

@@ -9,7 +9,7 @@ $z-layers: (
 	".editor-block-list__block {core/image aligned left or right}": 20,
 	".editor-block-list__block {core/image aligned wide or fullwide}": 20,
 	".freeform-toolbar": 10,
-	".editor-block-list__breadcrumb": 1,
+	".editor-block-list__breadcrumb": 1000000000, // used as a drag handler, we want it to be shown above the entire UI
 	".components-form-toggle__input": 1,
 	".editor-inserter__tabs": 1,
 	".editor-inserter__tab.is-active": 1,
@@ -34,10 +34,7 @@ $z-layers: (
 	// Active pill button
 	".components-button.is-button {:focus or .is-primary}": 1,
 
-	// Should have lower index than anything else positioned inside the block containers
-	".editor-block-list__block-draggable": 0,
-
-	// The draggable element should show up above the entire UI
+	// The drag image should show up above the entire UI
 	".components-draggable__clone": 1000000000,
 
 	// Should have higher index than the inset/underlay used for dragging

packages/components/src/dashicon/index.js

@@ -15,12 +15,13 @@ export default class Dashicon extends Component {
 		return (
 			this.props.icon !== nextProps.icon ||
 			this.props.size !== nextProps.size ||
+			this.props.viewBox !== nextProps.viewBox ||
 			this.props.className !== nextProps.className
 		);
 	}
 
 	render() {
-		const { icon, className, size = 20 } = this.props;
+		const { icon, className, size = 20, viewBox = 20 } = this.props;
 		let path;
 
 		switch ( icon ) {
@@ -893,7 +894,7 @@ export default class Dashicon extends Component {
 				xmlns="http://www.w3.org/2000/svg"
 				width={ size }
 				height={ size }
-				viewBox="0 0 20 20"
+				viewBox={ '0 0 ' + viewBox + ' ' + viewBox } // TODO: if we like this approach, remove this hack and implement upstream
 			>
 				<path d={ path } />
 			</svg>

packages/components/src/draggable/index.js

@@ -9,6 +9,7 @@ import classnames from 'classnames';
  */
 import { Component } from '@wordpress/element';
 import { withSafeTimeout } from '@wordpress/compose';
+import deprecated from '@wordpress/deprecated';
 
 const dragImageClass = 'components-draggable__invisible-drag-image';
 const cloneWrapperClass = 'components-draggable__clone';
@@ -19,6 +20,11 @@ class Draggable extends Component {
 	constructor() {
 		super( ...arguments );
 
+		deprecated( 'wp.components.Draggable', {
+			version: 3.7,
+			alternative: 'wp.components.withDraggable',
+		} );
+
 		this.onDragStart = this.onDragStart.bind( this );
 		this.onDragOver = this.onDragOver.bind( this );
 		this.onDragEnd = this.onDragEnd.bind( this );

packages/components/src/higher-order/with-draggable/README.md

@@ -0,0 +1,79 @@
+# withDraggable
+
+`withDraggable` is a Higher-Order Component that provides a way to set up a cross-browser (including IE) customisable drag image, and the transfer data for the drag event. It decouples the drag handle and the element to drag: it wraps the component that will be the drag handle, and it should be provided the DOM ID of the element to drag.
+
+Note that the drag handle needs to declare the `draggable="true"` property. The `withDraggable` component only takes care of the logic to setup the drag image and the transfer data, but is not concerned with creating an actual DOM element that is draggable.
+
+## Props
+
+The component injects the following props into the wrapped component:
+
+### initDragging
+
+A function that initializes the drag event, setting up the transfer data and creating the drag image. It returns a function to be called on the `dragstart` DOM event.
+
+- Type: `Function`
+- Required: Yes
+- Arguments:
+	- `elementId`: DOM id of the element to be dragged
+	- `data`: the [data](https://developer.mozilla.org/en-US/docs/Web/API/DragEvent/dataTransfer) to be transfered by the event
+
+## Usage
+
+```jsx
+import { Dashicon, Panel, PanelBody, withDraggable } from '@wordpress/components';
+
+const MyDraggable = ( { initDragging } ) => (
+	<div id="draggable-panel">
+		<Panel header="Draggable panel" >
+			<PanelBody>
+					<Dashicon
+						icon="move"
+						draggable="true"
+						onDragStart={ initDragging( "draggable-panel", {} ) } />
+			</PanelBody>
+		</Panel>
+	</div>
+);
+
+export default withDraggable( MyDraggable );
+```
+
+If the wrapped element would want to inject their own logic into the `dragstart` event, it should initialize the `initDragging` prop provided by `withDraggable` in that event handler. For example:
+
+```jsx
+
+import { Dashicon, Panel, PanelBody, withDraggable } from '@wordpress/components';
+
+const class MyDraggable extends Component {
+
+	constructor() {
+		super( ...arguments );
+		this.myDragStart = this.myDragStart.bind( this );
+	}
+
+	myDragStart( event ){
+		this.props.initDragging( 'draggable-panel', {} )( event );
+
+		// can do whatever is necessary after the event has been set up
+	}
+
+	render( ) {
+		return (
+			<div id="draggable-panel">
+				<Panel header="Draggable panel" >
+					<PanelBody>
+						<Dashicon
+							icon="move"
+							draggable="true"
+							onDragStart={ myDragStart }
+							/>
+					</PanelBody>
+				</Panel>
+			</div>
+		);
+	}
+}
+
+export default withDraggable( MyDraggable );
+```

packages/components/src/higher-order/with-draggable/index.js

@@ -0,0 +1,154 @@
+/**
+ * WordPress Dependencies
+ */
+import { Component } from '@wordpress/element';
+import { createHigherOrderComponent } from '@wordpress/compose';
+
+const dragImageClass = 'components-draggable__invisible-drag-image';
+const cloneWrapperClass = 'components-draggable__clone';
+const cloneHeightTransformationBreakpoint = 700;
+const clonePadding = 20;
+
+const withDraggable = createHigherOrderComponent(
+	( OriginalComponent ) => {
+		return class extends Component {
+			constructor() {
+				super( ...arguments );
+				this.onDragStart = this.onDragStart.bind( this );
+				this.onDragOver = this.onDragOver.bind( this );
+				this.onDragEnd = this.onDragEnd.bind( this );
+				this.resetDragState = this.resetDragState.bind( this );
+			}
+
+			componentWillUnmount() {
+				this.resetDragState();
+			}
+
+			/**
+			 * Function that creates the dragstart event handler.
+			 *
+			 * @param  {string} elementId The HTML id of the element to be dragged.
+			 * @param  {Object} data The data to be set to the event's dataTransfer - to be accessible in any later drop logic.
+			 * @return {function} A function for wrapped components to use as their onDragStart handler.
+			 */
+			onDragStart( elementId, data ) {
+				return ( event ) => {
+					const element = document.getElementById( elementId );
+					if ( ! element || ! data ) {
+						event.preventDefault();
+						return;
+					}
+
+					event.dataTransfer.setData( 'text', JSON.stringify( data ) );
+
+					// Set a fake drag image to avoid browser defaults. Remove from DOM
+					// right after. event.dataTransfer.setDragImage is not supported yet in
+					// IE, we need to check for its existence first.
+					if ( 'function' === typeof event.dataTransfer.setDragImage ) {
+						const dragImage = document.createElement( 'div' );
+						dragImage.id = `drag-image-${ elementId }`;
+						dragImage.classList.add( dragImageClass );
+						document.body.appendChild( dragImage );
+						event.dataTransfer.setDragImage( dragImage, 0, 0 );
+						setTimeout( () => {
+							document.body.removeChild( dragImage );
+						} );
+					}
+
+					// Prepare element clone and append to element wrapper.
+					const elementRect = element.getBoundingClientRect();
+					const elementWrapper = element.parentNode;
+					const elementTopOffset = parseInt( elementRect.top, 10 );
+					const elementLeftOffset = parseInt( elementRect.left, 10 );
+					const clone = element.cloneNode( true );
+					clone.id = `clone-${ elementId }`;
+					this.cloneWrapper = document.createElement( 'div' );
+					this.cloneWrapper.classList.add( cloneWrapperClass );
+					this.cloneWrapper.style.width = `${ elementRect.width + ( clonePadding * 2 ) }px`;
+
+					if ( elementRect.height > cloneHeightTransformationBreakpoint ) {
+						// Scale down clone if original element is larger than 700px.
+						this.cloneWrapper.style.transform = 'scale(0.5)';
+						this.cloneWrapper.style.transformOrigin = 'top left';
+						// Position clone near the cursor.
+						this.cloneWrapper.style.top = `${ event.clientY - 100 }px`;
+						this.cloneWrapper.style.left = `${ event.clientX }px`;
+					} else {
+						// Position clone right over the original element (20px padding).
+						this.cloneWrapper.style.top = `${ elementTopOffset - clonePadding }px`;
+						this.cloneWrapper.style.left = `${ elementLeftOffset - clonePadding }px`;
+					}
+
+					// Hack: Remove iFrames as it's causing the embeds drag clone to freeze
+					[ ...clone.querySelectorAll( 'iframe' ) ].forEach( ( child ) => child.parentNode.removeChild( child ) );
+
+					this.cloneWrapper.appendChild( clone );
+					elementWrapper.appendChild( this.cloneWrapper );
+
+					// Mark the current cursor coordinates.
+					this.cursorLeft = event.clientX;
+					this.cursorTop = event.clientY;
+					// Update cursor to 'grabbing', document wide.
+					document.body.classList.add( 'is-dragging-components-draggable' );
+
+					// connect listeners
+					document.addEventListener( 'dragover', this.onDragOver );
+					document.addEventListener( 'dragend', this.onDragEnd );
+				};
+			}
+
+			/**
+			 * Updates positioning of element clone based on mouse movement during dragging.
+			 * @param  {Object} event     The non-custom DragEvent.
+			 */
+			onDragOver( event ) {
+				this.cloneWrapper.style.top =
+					`${ parseInt( this.cloneWrapper.style.top, 10 ) + event.clientY - this.cursorTop }px`;
+				this.cloneWrapper.style.left =
+					`${ parseInt( this.cloneWrapper.style.left, 10 ) + event.clientX - this.cursorLeft }px`;
+
+				// Update cursor coordinates.
+				this.cursorLeft = event.clientX;
+				this.cursorTop = event.clientY;
+			}
+
+			/**
+			 * Removes the element clone, resets cursor, and removes drag listener.
+			 */
+			onDragEnd( ) {
+				this.resetDragState();
+			}
+
+			/**
+			 * Cleans up drag state when drag has completed, or component unmounts
+			 * while dragging.
+			 */
+			resetDragState() {
+				// Remove listeners
+				document.removeEventListener( 'dragover', this.onDragOver );
+				document.removeEventListener( 'dragend', this.onDragEnd );
+
+				// Remove drag clone
+				if ( this.cloneWrapper && this.cloneWrapper.parentNode ) {
+					this.cloneWrapper.parentNode.removeChild( this.cloneWrapper );
+					this.cloneWrapper = null;
+				}
+
+				// Reset cursor.
+				document.body.classList.remove( 'is-dragging-components-draggable' );
+			}
+
+			render() {
+				return (
+					<OriginalComponent
+						initDragging={ this.onDragStart }
+						{ ...this.props }
+					/>
+				);
+			}
+		};
+	},
+	'withDraggable'
+);
+
+export default withDraggable;

packages/components/src/higher-order/with-draggable/style.scss

@@ -0,0 +1,20 @@
+body.is-dragging-components-draggable {
+	cursor: move;/* Fallback for IE/Edge < 14 */
+	cursor: grabbing !important;
+}
+
+.components-draggable__invisible-drag-image {
+	position: fixed;
+	left: -1000px;
+	height: 50px;
+	width: 50px;
+}
+
+.components-draggable__clone {
+	position: fixed;
+	padding: 20px;
+	background: transparent;
+	pointer-events: none;
+	z-index: z-index(".components-draggable__clone");
+	opacity: 0.8;
+}

packages/components/src/index.js

@@ -62,6 +62,7 @@ export { default as navigateRegions } from './higher-order/navigate-regions';
 export { default as withAPIData } from './higher-order/with-api-data';
 export { default as withContext } from './higher-order/with-context';
 export { default as withConstrainedTabbing } from './higher-order/with-constrained-tabbing';
+export { default as withDraggable } from './higher-order/with-draggable';
 export { default as withFallbackStyles } from './higher-order/with-fallback-styles';
 export { default as withFilters } from './higher-order/with-filters';
 export { default as withFocusOutside } from './higher-order/with-focus-outside';