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import { EventEmitter, NgZone } from "@angular/core"; | |
import { Observable, throttle } from "rxjs"; | |
export class NoopNgZone implements NgZone { | |
readonly hasPendingMicrotasks = false; | |
readonly hasPendingMacrotasks = false; | |
readonly isStable = true; | |
readonly onUnstable = new EventEmitter<any>(); | |
readonly onError = new EventEmitter<any>(); | |
private readonly onStableEmitter = new EventEmitter<any>(); | |
private readonly onMicrotaskEmptyEmitter = new EventEmitter<any>(); | |
private readonly schedule = getCallbackScheduler(); | |
get onMicrotaskEmpty() { | |
this.schedule(() => this.onMicrotaskEmptyEmitter.emit({})); | |
return this.onMicrotaskEmptyEmitter.pipe( | |
// coalescing - remove this line if it brings issues | |
throttle(() => getObservableScheduler(this.schedule), { leading: true, trailing: false }), | |
) as EventEmitter<any>; | |
} | |
get onStable() { | |
this.schedule(() => this.onStableEmitter.emit({})); | |
return this.onStableEmitter.pipe( | |
// coalescing - remove this line if it brings issues | |
throttle(() => getObservableScheduler(this.schedule), { leading: true, trailing: false }), | |
) as EventEmitter<any>; | |
} | |
run<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any): T { | |
return fn.apply(applyThis, applyArgs); | |
} | |
runGuarded<T>( | |
fn: (...args: any[]) => any, | |
applyThis?: any, | |
applyArgs?: any | |
): T { | |
return fn.apply(applyThis, applyArgs); | |
} | |
runOutsideAngular<T>(fn: (...args: any[]) => T): T { | |
return fn(); | |
} | |
runTask<T>( | |
fn: (...args: any[]) => T, | |
applyThis?: any, | |
applyArgs?: any, | |
_name?: string | |
): T { | |
return fn.apply(applyThis, applyArgs); | |
} | |
emitOnStable() { | |
this.onStableEmitter.emit({}); | |
} | |
emitOnMicrotaskEmpty() { | |
this.onMicrotaskEmptyEmitter.emit({}); | |
} | |
} | |
export function provideNoopNgZone() { | |
return { provide: NgZone, useClass: NoopNgZone }; | |
} | |
export function getObservableScheduler(scheduler: Function): Observable<boolean> { | |
return new Observable<boolean>((subscriber) => { | |
scheduler(() => subscriber.next(true)); | |
}); | |
} | |
const global: any = globalThis; | |
/** | |
* In this file, code below is copied from: | |
* https://github.com/angular/angular/blob/5328be6660b7ef388720edab4b3f2d0fa2699203/packages/core/src/util/callback_scheduler.ts | |
* | |
* @license | |
* Copyright Google LLC All Rights Reserved. | |
* | |
* Use of this source code is governed by an MIT-style license that can be | |
* found in the LICENSE file at https://angular.io/license | |
* | |
* Gets a scheduling function that runs the callback after the first of setTimeout and | |
* requestAnimationFrame resolves. | |
* | |
* - `requestAnimationFrame` ensures that change detection runs ahead of a browser repaint. | |
* This ensures that the create and update passes of a change detection always happen | |
* in the same frame. | |
* - When the browser is resource-starved, `rAF` can execute _before_ a `setTimeout` because | |
* rendering is a very high priority process. This means that `setTimeout` cannot guarantee | |
* same-frame create and update pass, when `setTimeout` is used to schedule the update phase. | |
* - While `rAF` gives us the desirable same-frame updates, it has two limitations that | |
* prevent it from being used alone. First, it does not run in background tabs, which would | |
* prevent Angular from initializing an application when opened in a new tab (for example). | |
* Second, repeated calls to requestAnimationFrame will execute at the refresh rate of the | |
* hardware (~16ms for a 60Hz display). This would cause significant slowdown of tests that | |
* are written with several updates and asserts in the form of "update; await stable; assert;". | |
* - Both `setTimeout` and `rAF` are able to "coalesce" several events from a single user | |
* interaction into a single change detection. Importantly, this reduces view tree traversals when | |
* compared to an alternative timing mechanism like `queueMicrotask`, where change detection would | |
* then be interleaves between each event. | |
* | |
* By running change detection after the first of `setTimeout` and `rAF` to execute, we get the | |
* best of both worlds. | |
*/ | |
export function getCallbackScheduler(): (callback: Function) => void { | |
// Note: the `getNativeRequestAnimationFrame` is used in the `NgZone` class, but we cannot use the | |
// `inject` function. The `NgZone` instance may be created manually, and thus the injection | |
// context will be unavailable. This might be enough to check whether `requestAnimationFrame` is | |
// available because otherwise, we'll fall back to `setTimeout`. | |
const hasRequestAnimationFrame = typeof global['requestAnimationFrame'] === 'function'; | |
let nativeRequestAnimationFrame = | |
hasRequestAnimationFrame ? global['requestAnimationFrame'] : null; | |
let nativeSetTimeout = global['setTimeout']; | |
// @ts-ignore | |
if (typeof Zone !== 'undefined') { | |
// Note: zone.js sets original implementations on patched APIs behind the | |
// `__zone_symbol__OriginalDelegate` key (see `attachOriginToPatched`). Given the following | |
// example: `window.requestAnimationFrame.__zone_symbol__OriginalDelegate`; this would return an | |
// unpatched implementation of the `requestAnimationFrame`, which isn't intercepted by the | |
// Angular zone. We use the unpatched implementation to avoid another change detection when | |
// coalescing tasks. | |
// @ts-ignore | |
const ORIGINAL_DELEGATE_SYMBOL = (Zone as any).__symbol__('OriginalDelegate'); | |
if (nativeRequestAnimationFrame) { | |
nativeRequestAnimationFrame = | |
(nativeRequestAnimationFrame as any)[ORIGINAL_DELEGATE_SYMBOL] ?? | |
nativeRequestAnimationFrame; | |
} | |
nativeSetTimeout = (nativeSetTimeout as any)[ORIGINAL_DELEGATE_SYMBOL] ?? nativeSetTimeout; | |
} | |
return (callback: Function) => { | |
let executeCallback = true; | |
nativeSetTimeout(() => { | |
if (!executeCallback) { | |
return; | |
} | |
executeCallback = false; | |
callback(); | |
}); | |
nativeRequestAnimationFrame?.(() => { | |
if (!executeCallback) { | |
return; | |
} | |
executeCallback = false; | |
callback(); | |
}); | |
}; | |
} |
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