Merge pull request #94 from ckeditor/t/ckeditor5-image/241

Feature: Introduced image widget resizer. See ckeditor/ckeditor5-image#241.

package.json

@@ -12,7 +12,8 @@
     "@ckeditor/ckeditor5-core": "^12.2.1",
     "@ckeditor/ckeditor5-engine": "^13.2.1",
     "@ckeditor/ckeditor5-ui": "^13.0.2",
-    "@ckeditor/ckeditor5-utils": "^13.0.1"
+    "@ckeditor/ckeditor5-utils": "^13.0.1",
+    "lodash-es": "^4.17.10"
   },
   "devDependencies": {
     "@ckeditor/ckeditor5-basic-styles": "^11.1.3",

src/widgetresize.js

@@ -0,0 +1,162 @@
+/**
+ * @license Copyright (c) 2003-2019, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/**
+ * @module widget/widgetresize
+ */
+
+import Plugin from '@ckeditor/ckeditor5-core/src/plugin';
+import Resizer from './widgetresize/resizer';
+import DomEmitterMixin from '@ckeditor/ckeditor5-utils/src/dom/emittermixin';
+import global from '@ckeditor/ckeditor5-utils/src/dom/global';
+import { throttle } from 'lodash-es';
+
+/**
+ * Widget resize feature plugin.
+ *
+ * Use the {@link module:widget/widgetresize~WidgetResize#attachTo} method to create a resizer for the specified widget.
+ *
+ * @extends module:core/plugin~Plugin
+ */
+export default class WidgetResize extends Plugin {
+	/**
+	 * @inheritDoc
+	 */
+	static get pluginName() {
+		return 'WidgetResize';
+	}
+
+	init() {
+		this.resizers = [];
+		this.activeResizer = null;
+
+		const domDocument = global.window.document;
+		const THROTTLE_THRESHOLD = 16; // 16ms = ~60fps
+
+		this.editor.model.schema.setAttributeProperties( 'width', {
+			isFormatting: true
+		} );
+
+		this._observer = Object.create( DomEmitterMixin );
+
+		this._observer.listenTo( domDocument, 'mousedown', ( event, domEventData ) => {
+			if ( !Resizer.isResizeHandle( domEventData.target ) ) {
+				return;
+			}
+
+			const resizeHandle = domEventData.target;
+
+			this.activeResizer = this._getResizerByHandle( resizeHandle );
+
+			if ( this.activeResizer ) {
+				this.activeResizer.begin( resizeHandle );
+			}
+		} );
+
+		this._observer.listenTo( domDocument, 'mousemove', throttle( ( event, domEventData ) => {
+			if ( this.activeResizer ) {
+				this.activeResizer.updateSize( domEventData );
+			}
+		}, THROTTLE_THRESHOLD ) );
+
+		this._observer.listenTo( domDocument, 'mouseup', () => {
+			if ( this.activeResizer ) {
+				this.activeResizer.commit();
+
+				this.activeResizer = null;
+			}
+		} );
+
+		const redrawResizers = throttle( () => {
+			for ( const context of this.resizers ) {
+				context.redraw();
+			}
+		}, THROTTLE_THRESHOLD );
+
+		// Redrawing on any change of the UI of the editor (including content changes).
+		this.editor.ui.on( 'update', redrawResizers );
+
+		// Resizers need to be redrawn upon window resize, because new window might shrink resize host.
+		this._observer.listenTo( global.window, 'resize', redrawResizers );
+	}
+
+	destroy() {
+		this._observer.stopListening();
+	}
+
+	/**
+	 * @param {module:widget/widgetresize~ResizerOptions} [options] Resizer options.
+	 * @returns {module:widget/widgetresize/resizer~Resizer}
+	 */
+	attachTo( options ) {
+		const resizer = new Resizer( options );
+
+		resizer.attach();
+
+		this.editor.editing.view.once( 'render', () => resizer.redraw() );
+
+		this.resizers.push( resizer );
+
+		return resizer;
+	}
+
+	_getResizerByHandle( domResizeHandle ) {
+		for ( const resizer of this.resizers ) {
+			if ( resizer.containsHandle( domResizeHandle ) ) {
+				return resizer;
+			}
+		}
+	}
+}
+
+/**
+ * Interface describing a resizer. It allows to specify resizing host, custom logic for calculating aspect ratio etc.
+ *
+ * @interface ResizerOptions
+ */
+
+/**
+ * @member {module:engine/model/element~Element} module:widget/widgetresize~ResizerOptions#modelElement
+ */
+
+/**
+ * @member {module:engine/view/containerelement~ContainerElement} module:widget/widgetresize~ResizerOptions#viewElement
+ */
+
+/**
+ * @member {module:engine/view/downcastwriter~DowncastWriter} module:widget/widgetresize~ResizerOptions#downcastWriter
+ */
+
+/**
+ * A callback to be executed once resizing process is done.
+ *
+ * It receives a `Number` (`newValue`) as a parameter.
+ *
+ * For example, {@link module:image/imageresize~ImageResize} uses it to execute image resize command,
+ * which puts new value into the model.
+ *
+ * ```js
+ * {
+ *	modelElement: data.item,
+ *	viewElement: widget,
+ *	downcastWriter: conversionApi.writer,
+ *
+ *	onCommit( newValue ) {
+ *		editor.execute( 'imageResize', { width: newValue } );
+ *	}
+ * };
+ * ```
+ *
+ *
+ * @member {Function} module:widget/widgetresize~ResizerOptions#onCommit
+ */
+
+/**
+ * @member {Function} module:widget/widgetresize~ResizerOptions#getResizeHost
+ */
+
+/**
+ * @member {Function} module:widget/widgetresize~ResizerOptions#isCentered
+ */