1 import { AsyncAction } from './AsyncAction';
2 import { AnimationFrameScheduler } from './AnimationFrameScheduler';
3 import { SchedulerAction } from '../types';
6 * We need this JSDoc comment for affecting ESDoc.
10 export class AnimationFrameAction<T> extends AsyncAction<T> {
12 constructor(protected scheduler: AnimationFrameScheduler,
13 protected work: (this: SchedulerAction<T>, state?: T) => void) {
14 super(scheduler, work);
17 protected requestAsyncId(scheduler: AnimationFrameScheduler, id?: any, delay: number = 0): any {
18 // If delay is greater than 0, request as an async action.
19 if (delay !== null && delay > 0) {
20 return super.requestAsyncId(scheduler, id, delay);
22 // Push the action to the end of the scheduler queue.
23 scheduler.actions.push(this);
24 // If an animation frame has already been requested, don't request another
25 // one. If an animation frame hasn't been requested yet, request one. Return
26 // the current animation frame request id.
27 return scheduler.scheduled || (scheduler.scheduled = requestAnimationFrame(
28 () => scheduler.flush(null)));
30 protected recycleAsyncId(scheduler: AnimationFrameScheduler, id?: any, delay: number = 0): any {
31 // If delay exists and is greater than 0, or if the delay is null (the
32 // action wasn't rescheduled) but was originally scheduled as an async
33 // action, then recycle as an async action.
34 if ((delay !== null && delay > 0) || (delay === null && this.delay > 0)) {
35 return super.recycleAsyncId(scheduler, id, delay);
37 // If the scheduler queue is empty, cancel the requested animation frame and
38 // set the scheduled flag to undefined so the next AnimationFrameAction will
40 if (scheduler.actions.length === 0) {
41 cancelAnimationFrame(id);
42 scheduler.scheduled = undefined;
44 // Return undefined so the action knows to request a new async id if it's rescheduled.