/** * @license Copyright (c) 2003-2015, CKSource - Frederico Knabben. All rights reserved. * For licensing, see LICENSE.md. */ /** * @module engine/view/observer/observer */ import DomEmitterMixin from 'ckeditor5-utils/src/dom/emittermixin'; import mix from 'ckeditor5-utils/src/mix'; /** * Abstract base observer class. Observers are classes which observe changes on DOM elements, do the preliminary * processing and fire events on the {@link module:engine/view/document~Document} objects. Observers can also add features to the view, * for instance by updating its status or marking elements which need refresh on DOM events. * * @abstract */ export default class Observer { /** * Creates an instance of the observer. * * @param {module:engine/view/document~Document} document */ constructor( document ) { /** * Reference to the {@link module:engine/view/document~Document} object. * * @readonly * @member {module:engine/view/document~Document} */ this.document = document; /** * State of the observer. If it is disabled events will not be fired. * * @readonly * @member {Boolean} */ this.isEnabled = false; } /** * Enables the observer. This method is called when then observer is registered to the * {@link module:engine/view/document~Document} and after {@link module:engine/view/document~Document#render rendering} * (all observers are {@link #disable disabled} before rendering). * * A typical use case for disabling observers is that mutation observers need to be disabled for the rendering. * However, a child class may not need to be disabled, so it can implement an empty method. * * @see module:engine/view/observer/observer~Observer#disable */ enable() { this.isEnabled = true; } /** * Disables the observer. This method is called before * {@link module:engine/view/document~Document#render rendering} to prevent firing events during rendering. * * @see module:engine/view/observer/observer~Observer#enable */ disable() { this.isEnabled = false; } /** * Disables and destroys the observer, among others removes event listeners created by the observer. */ destroy() { this.disable(); this.stopListening(); } /** * Starts observing the given root element. * * @method #observe * @param {HTMLElement} domElement * @param {String} name The name of the root element. */ } mix( Observer, DomEmitterMixin );