Merge pull request #17098 from ckeditor/ck/16412

Feature (engine): Add `usePassive` option to the `DomEventObserver` that enables listening passive events. Closes #16412

packages/ckeditor5-engine/src/view/observer/domeventobserver.ts

@@ -56,6 +56,12 @@ export default abstract class DomEventObserver<
  */
  public useCapture: boolean = false;
 
+ /**
+ * If set to `true`, indicates that the function specified by listener will never call `preventDefault()`.
+ * Default value is `false`.
+ */
+ public usePassive: boolean = false;
+
  /**
  * Callback which should be called when the DOM event occurred. Note that the callback will not be called if
  * observer {@link #isEnabled is not enabled}.
@@ -75,7 +81,7 @@ export default abstract class DomEventObserver<
  if ( this.isEnabled && !this.checkShouldIgnoreEventFromTarget( domEvent.target as any ) ) {
  this.onDomEvent( domEvent );
  }
- }, { useCapture: this.useCapture } );
+ }, { useCapture: this.useCapture, usePassive: this.usePassive } );
  } );
  }
 

packages/ckeditor5-engine/tests/view/observer/domeventobserver.js

@@ -44,6 +44,14 @@ class ClickCapturingObserver extends ClickObserver {
  }
 }
 
+class ClickPassiveObserver extends ClickObserver {
+ constructor( view ) {
+ super( view );
+
+ this.usePassive = true;
+ }
+}
+
 describe( 'DomEventObserver', () => {
  let view, viewDocument;
 
@@ -184,6 +192,23 @@ describe( 'DomEventObserver', () => {
  childDomElement.dispatchEvent( domEvent );
  } );
 
+ it( 'should allow to listen passive events', () => {
+ const domElement = document.createElement( 'div' );
+ createViewRoot( viewDocument );
+ view.attachDomRoot( domElement );
+
+ const eventHandlerSpy = sinon.spy( ClickPassiveObserver.prototype, 'listenTo' );
+
+ view.addObserver( ClickPassiveObserver );
+
+ expect( eventHandlerSpy ).to.be.calledWith( domElement, 'click', sinon.match.func, {
+ useCapture: false,
+ usePassive: true
+ } );
+
+ eventHandlerSpy.restore();
+ } );
+
  describe( 'integration with UIElement', () => {
  let domRoot, domEvent, evtSpy, uiElement;