Implementing a custom editor creator

import { Editor, getDataFromElement, setDataInElement } from 'ckeditor5';

/**
 * The multi-root editor implementation. It provides inline editables and a single toolbar.
 *
 * Unlike other editors, the toolbar is not rendered automatically and needs to be attached to the DOM manually.
 *
 * This type of an editor is dedicated to integrations which require a customized UI with an open
 * structure, allowing developers to specify the exact location of the interface.
 *
 * @implements module:core/editor/editorwithui~EditorWithUI
 * @extends module:core/editor/editor~Editor
 */
class MultirootEditor extends Editor {
	/**
	* Creates an instance of the multi-root editor.
	*
	* **Note:** Do not use the constructor to create editor instances. Use the static `MultirootEditor.create()` method instead.
	*
	* @protected
	* @param {Object.<String,HTMLElement>} sourceElements The list of DOM elements that will be the source
	* for the created editor (on which the editor will be initialized).
	* @param {module:core/editor/editorconfig~EditorConfig} config The editor configuration.
	*/
	constructor( sourceElements, config ) {
		super( config );

		if ( this.config.get( 'initialData' ) === undefined ) {
			// Create initial data object containing data from all roots.
			const initialData = {};

			for ( const rootName of Object.keys( sourceElements ) ) {
				initialData[ rootName ] = getDataFromElement( sourceElements[ rootName ] );
			}

			this.config.set( 'initialData', initialData );
		}

		// Create root and UIView element for each editable container.
		for ( const rootName of Object.keys( sourceElements ) ) {
			this.model.document.createRoot( '$root', rootName );
		}

		this.ui = new MultirootEditorUI( this, new MultirootEditorUIView( this.locale, this.editing.view, sourceElements ) );
	}

	/**
	* @inheritDoc
	*/
	destroy() {
		// Cache the data and editable DOM elements, then destroy.
		// It's safe to assume that the model->view conversion will not work after super.destroy(),
		// same as `ui.getEditableElement()` method will not return editables.
		const data = {};
		const editables = {};
		const editablesNames = Array.from( this.ui.getEditableElementsNames() );

		for ( const rootName of editablesNames ) {
			data[ rootName ] = this.getData( { rootName } );
			editables[ rootName ] = this.ui.getEditableElement( rootName );
		}

		this.ui.destroy();

		return super.destroy()
			.then( () => {
				for ( const rootName of editablesNames ) {
					setDataInElement( editables[ rootName ], data[ rootName ] );
				}
			} );
	}

	/**
	* Creates a multi-root editor instance.
	*
	* @param {Object.<String,HTMLElement>} sourceElements The list of DOM elements that will be the source
	* for the created editor (on which the editor will be initialized).
	* @param {module:core/editor/editorconfig~EditorConfig} config The editor configuration.
	* @returns {Promise} A promise resolved once the editor is ready. The promise returns the created multi-root editor instance.
	*/
	static create( sourceElements, config ) {
		return new Promise( resolve => {
			const editor = new this( sourceElements, config );

			resolve(
				editor.initPlugins()
					.then( () => editor.ui.init() )
					.then( () => editor.data.init( editor.config.get( 'initialData' ) ) )
					.then( () => editor.fire( 'ready' ) )
					.then( () => editor )
			);
		} );
	}
}

import { EditorUI, enablePlaceholder } from 'ckeditor5';

/**
 * The multi-root editor UI class.
 *
 * @extends module:ui/editorui/editorui~EditorUI
 */
class MultirootEditorUI extends EditorUI {
	/**
	* Creates an instance of the multi-root editor UI class.
	*
	* @param {module:core/editor/editor~Editor} editor The editor instance.
	* @param {module:ui/editorui/editoruiview~EditorUIView} view The view of the UI.
	*/
	constructor( editor, view ) {
		super( editor );

		/**
		* The main (top–most) view of the editor UI.
		*
		* @readonly
		* @member {module:ui/editorui/editoruiview~EditorUIView} #view
		*/
		this.view = view;
	}

	/**
	* Initializes the UI.
	*/
	init() {
		const view = this.view;
		const editor = this.editor;
		const editingView = editor.editing.view;

		let lastFocusedEditableElement;

		view.render();

		// Keep track of the last focused editable element. Knowing which one was focused
		// is useful when the focus moves from editable to other UI components like balloons
		// (especially inputs) but the editable remains the "focus context" (e.g. link balloon
		// attached to a link in an editable). In this case, the editable should preserve visual
		// focus styles.
		this.focusTracker.on( 'change:focusedElement', ( evt, name, focusedElement ) => {
			for ( const editable of this.view.editables ) {
				if ( editable.element === focusedElement ) {
					lastFocusedEditableElement = editable.element;
				}
			}
		} );

		// If the focus tracker loses focus, stop tracking the last focused editable element.
		// Wherever the focus is restored, it will no longer be in the context of that editable
		// because the focus "came from the outside", as opposed to the focus moving from one element
		// to another within the editor UI.
		this.focusTracker.on( 'change:isFocused', ( evt, name, isFocused ) => {
			if ( !isFocused ) {
				lastFocusedEditableElement = null;
			}
		} );

		for ( const editable of this.view.editables ) {
			// The editable UI element in DOM is available for sure only after the editor UI view has been rendered.
			// But it can be available earlier if a DOM element has been passed to MultirootEditor.create().
			const editableElement = editable.element;

			// Register each editable UI view in the editor.
			this.setEditableElement( editable.name, editableElement );

			// Let the editable UI element respond to the changes in the global editor focus
			// tracker. It has been added to the same tracker a few lines above but, in reality, there are
			// many focusable areas in the editor, like balloons, toolbars or dropdowns and as long
			// as they have focus, the editable should act like it is focused too (although technically
			// it isn't), e.g. by setting the proper CSS class, visually announcing focus to the user.
			// Doing otherwise will result in editable focus styles disappearing, once e.g. the
			// toolbar gets focused.
			editable.bind( 'isFocused' ).to( this.focusTracker, 'isFocused', this.focusTracker, 'focusedElement',
				( isFocused, focusedElement ) => {
					// When the focus tracker is blurred, it means the focus moved out of the editor UI.
					// No editable will maintain focus then.
					if ( !isFocused ) {
						return false;
					}

					// If the focus tracker says the editor UI is focused and currently focused element
					// is the editable, then the editable should be visually marked as focused too.
					if ( focusedElement === editableElement ) {
						return true;
					}
					// If the focus tracker says the editor UI is focused but the focused element is
					// not an editable, it is possible that the editable is still (context–)focused.
					// For instance, the focused element could be an input inside of a balloon attached
					// to the content in the editable. In such case, the editable should remain _visually_
					// focused even though technically the focus is somewhere else. The focus moved from
					// the editable to the input but the focus context remained the same.
					else {
						return lastFocusedEditableElement === editableElement;
					}
				} );

			// Bind the editable UI element to the editing view, making it an end– and entry–point
			// of the editor's engine. This is where the engine meets the UI.
			editingView.attachDomRoot( editableElement, editable.name );
		}

		this._initPlaceholder();
		this._initToolbar();
		this.fire( 'ready' );
	}

	/**
	* @inheritDoc
	*/
	destroy() {
		super.destroy();

		const view = this.view;
		const editingView = this.editor.editing.view;

		for ( const editable of this.view.editables ) {
			editingView.detachDomRoot( editable.name );
		}

		view.destroy();
	}

	/**
	* Initializes the editor main toolbar and its panel.
	*
	* @private
	*/
	_initToolbar() {
		const editor = this.editor;
		const view = this.view;
		const toolbar = view.toolbar;

		toolbar.fillFromConfig( editor.config.get( 'toolbar' ), this.componentFactory );

		// Register the toolbar so it becomes available for Alt+F10 and Esc navigation.
		this.addToolbar( view.toolbar );
	}

	/**
	* Enable the placeholder text on the editing root, if any was configured.
	*
	* @private
	*/
	_initPlaceholder() {
		const editor = this.editor;
		const editingView = editor.editing.view;

		for ( const editable of this.view.editables ) {
			const editingRoot = editingView.document.getRoot( editable.name );
			const sourceElement = this.getEditableElement( editable.name );

			const placeholderText = editor.config.get( 'placeholder' )[ editable.name ] ||
				sourceElement && sourceElement.tagName.toLowerCase() === 'textarea' && sourceElement.getAttribute( 'placeholder' );

			if ( placeholderText ) {
				editingRoot.placeholder = placeholderText;

				enablePlaceholder( {
					view: editingView,
					element: editingRoot,
					isDirectHost: false,
					keepOnFocus: true
				} );
			}
		}
	}
}

import { EditorUIView, InlineEditableUIView, Template, ToolbarView } from 'ckeditor5';

/**
 * The multi-root editor UI view. It is a virtual view providing an inline editable, but without
 * any specific arrangement of the components in the DOM.
 *
 * @extends module:ui/editorui/editoruiview~EditorUIView
 */
class MultirootEditorUIView extends EditorUIView {
	/**
	* Creates an instance of the multi-root editor UI view.
	*
	* @param {module:utils/locale~Locale} locale The locale instance.
	* @param {module:engine/view/view~View} editingView The editing view instance this view is related to.
	* @param {Object.<String,HTMLElement>} editableElements The list of editable elements, containing name and html element
	* for each editable.
	*/
	constructor( locale, editingView, editableElements ) {
		super( locale );

		/**
		* The main toolbar of the multi-root editor UI.
		*
		* @readonly
		* @member {module:ui/toolbar/toolbarview~ToolbarView}
		*/
		this.toolbar = new ToolbarView( locale );

		/**
		* The editables of the multi-root editor UI.
		*
		* @readonly
		* @member {Array.<module:ui/editableui/inline/inlineeditableuiview~InlineEditableUIView>}
		*/
		this.editables = [];

		// Create InlineEditableUIView instance for each editable.
		for ( const editableName of Object.keys( editableElements ) ) {
			const editable = new InlineEditableUIView( locale, editingView, editableElements[ editableName ] );

			editable.name = editableName;
			this.editables.push( editable );
		}

		// This toolbar may be placed anywhere in the page so things like font size need to be reset in it.
		// Because of the above, make sure the toolbar supports rounded corners.
		// Also, make sure the toolbar has the proper dir attribute because its ancestor may not have one
		// and some toolbar item styles depend on this attribute.
		Template.extend( this.toolbar.template, {
			attributes: {
				class: [
					'ck-reset_all',
					'ck-rounded-corners'
				],
				dir: locale.uiLanguageDirection
			}
		} );
	}

	/**
	* @inheritDoc
	*/
	render() {
		super.render();

		this.registerChild( this.editables );
		this.registerChild( [ this.toolbar ] );
	}
}