src/view/observer/observer.js
/**
* @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
*/
/**
* @module engine/view/observer/observer
*/
import DomEmitterMixin from '@ckeditor/ckeditor5-utils/src/dom/emittermixin';
import mix from '@ckeditor/ckeditor5-utils/src/mix';
/**
* Abstract base observer class. Observers are classes which listen to DOM events, 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/view~View} view
*/
constructor( view ) {
/**
* Instance of the view controller.
*
* @readonly
* @member {module:engine/view/view~View}
*/
this.view = view;
/**
* Reference to the {@link module:engine/view/document~Document} object.
*
* @readonly
* @member {module:engine/view/document~Document}
*/
this.document = view.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 the observer is registered to the
* {@link module:engine/view/view~View} and after {@link module:engine/view/view~View#forceRender 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/view~View#forceRender 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 );