/
observer.ts
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/
observer.ts
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/**
* @license Copyright (c) 2003-2024, CKSource Holding sp. z o.o. 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';
import type Document from '../document.js';
import type View from '../view.js';
/**
* 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 a refresh on DOM events.
*/
export default abstract class Observer extends DomEmitterMixin() {
/**
* An instance of the view controller.
*/
public readonly view: View;
/**
* A reference to the {@link module:engine/view/document~Document} object.
*/
public readonly document: Document;
/**
* The state of the observer. If it is disabled, no events will be fired.
*/
private _isEnabled: boolean = false;
/**
* Creates an instance of the observer.
*/
constructor( view: View ) {
super();
this.view = view;
this.document = view.document;
}
/**
* The state of the observer. If it is disabled, no events will be fired.
*/
public get isEnabled(): boolean {
return this._isEnabled;
}
/**
* 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
*/
public enable(): void {
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
*/
public disable(): void {
this._isEnabled = false;
}
/**
* Disables and destroys the observer, among others removes event listeners created by the observer.
*/
public destroy(): void {
this.disable();
this.stopListening();
}
/**
* Checks whether a given DOM event should be ignored (should not be turned into a synthetic view document event).
*
* Currently, an event will be ignored only if its target or any of its ancestors has the `data-cke-ignore-events` attribute.
* This attribute can be used inside the structures generated by
* {@link module:engine/view/downcastwriter~DowncastWriter#createUIElement `DowncastWriter#createUIElement()`} to ignore events
* fired within a UI that should be excluded from CKEditor 5's realms.
*
* @param domTarget The DOM event target to check (usually an element, sometimes a text node and
* potentially sometimes a document, too).
* @returns Whether this event should be ignored by the observer.
*/
public checkShouldIgnoreEventFromTarget( domTarget: Node | null ): boolean {
if ( domTarget && domTarget.nodeType === 3 ) {
domTarget = domTarget.parentNode as any;
}
if ( !domTarget || domTarget.nodeType !== 1 ) {
return false;
}
return ( domTarget as any ).matches( '[data-cke-ignore-events], [data-cke-ignore-events] *' );
}
/**
* Starts observing given DOM element.
*
* @param domElement DOM element to observe.
* @param name The name of the related root element.
*/
public abstract observe( domElement: HTMLElement, name: string ): void;
/**
* Stops observing given DOM element.
*/
public abstract stopObserving( domElement: HTMLElement ): void;
}
/**
* The constructor of {@link ~Observer} subclass.
*/
export type ObserverConstructor = new ( view: View ) => Observer;