NathanWalker · Nov 12, 2020 · Sep 25, 2020 · Sep 25, 2020 · Sep 25, 2020 · Sep 28, 2020
diff --git a/packages/core/animation-frame/index.ts b/packages/core/animation-frame/index.ts
@@ -1,12 +1,18 @@
+import { queueMacrotask } from '../utils/macrotask-scheduler';
 import { FPSCallback } from '../fps-meter/fps-native';
 import { getTimeInFrameBase } from './animation-native';
+import { Trace } from 'trace';
 
 export interface FrameRequestCallback {
 	(time: number): void;
 }
 
+type AnimationFrameCallbacks = { [key: string]: FrameRequestCallback };
+
 let animationId = 0;
-let nextFrameAnimationCallbacks: { [key: string]: FrameRequestCallback } = {};
+let currentFrameAnimationCallbacks: AnimationFrameCallbacks = {}; // requests that were scheduled in this frame and must be called ASAP
+let currentFrameScheduled = false;
+let nextFrameAnimationCallbacks: AnimationFrameCallbacks = {}; // requests there were scheduled in another request and must be called in the next frame
 let shouldStop = true;
 let inAnimationFrame = false;
 let fpsCallback: FPSCallback;
@@ -23,40 +29,67 @@ function ensureNative() {
 	fpsCallback = new FPSCallback(doFrame);
 }
 
-function doFrame(currentTimeMillis: number) {
-	lastFrameTime = currentTimeMillis;
-	shouldStop = true;
-	const thisFrameCbs = nextFrameAnimationCallbacks;
-	nextFrameAnimationCallbacks = {};
+function callAnimationCallbacks(thisFrameCbs: AnimationFrameCallbacks, frameTime: number): void {
 	inAnimationFrame = true;
 	for (const animationId in thisFrameCbs) {
 		if (thisFrameCbs[animationId]) {
-			thisFrameCbs[animationId](lastFrameTime);
+			try {
+				thisFrameCbs[animationId](frameTime);
+			} catch (err) {
+				const msg = err ? err.stack || err : err;
+				Trace.write(`Error in requestAnimationFrame: ${msg}`, Trace.categories.Error, Trace.messageType.error);
+			}
 		}
 	}
 	inAnimationFrame = false;
+}
+
+function doCurrentFrame() {
+	// if we're not getting accurate frame times
+	// set last frame time as the current time
+	if (!fpsCallback || !fpsCallback.running) {
+		lastFrameTime = getTimeInFrameBase();
+	}
+	currentFrameScheduled = false;
+	const thisFrameCbs = currentFrameAnimationCallbacks;
+	currentFrameAnimationCallbacks = {};
+	callAnimationCallbacks(thisFrameCbs, lastFrameTime);
+}
+
+function doFrame(currentTimeMillis: number) {
+	lastFrameTime = currentTimeMillis;
+	shouldStop = true;
+	const thisFrameCbs = nextFrameAnimationCallbacks;
+	nextFrameAnimationCallbacks = {};
+	callAnimationCallbacks(thisFrameCbs, lastFrameTime);
 	if (shouldStop) {
 		fpsCallback.stop(); // TODO: check performance without stopping to allow consistent frame times
 	}
 }
 
+function ensureCurrentFrameScheduled() {
+	if (!currentFrameScheduled) {
+		currentFrameScheduled = true;
+		queueMacrotask(doCurrentFrame);
+	}
+}
+
 export function requestAnimationFrame(cb: FrameRequestCallback): number {
+	const animId = getNewId();
 	if (!inAnimationFrame) {
-		inAnimationFrame = true;
-		zonedCallback(cb)(getTimeInFrameBase()); // TODO: store and use lastFrameTime
-		inAnimationFrame = false;
-
-		return getNewId();
+		ensureCurrentFrameScheduled();
+		currentFrameAnimationCallbacks[animId] = zonedCallback(cb) as FrameRequestCallback;
+		return animId;
 	}
 	ensureNative();
-	const animId = getNewId();
 	nextFrameAnimationCallbacks[animId] = zonedCallback(cb) as FrameRequestCallback;
 	shouldStop = false;
 	fpsCallback.start();
 
 	return animId;
 }
 
-export function cancelAnimationFrame(id: number) {
+export function cancelAnimationFrame(id: number): void {
+	delete currentFrameAnimationCallbacks[id];
 	delete nextFrameAnimationCallbacks[id];
 }
diff --git a/packages/core/index.ts b/packages/core/index.ts
@@ -110,7 +110,7 @@ export * from './trace';
 
 export * from './ui';
 
-import { GC, isFontIconURI, isDataURI, isFileOrResourcePath, executeOnMainThread, mainThreadify, isMainThread, dispatchToMainThread, releaseNativeObject, getModuleName, openFile, openUrl, isRealDevice, layout, ad as androidUtils, iOSNativeHelper as iosUtils, Source, RESOURCE_PREFIX, FILE_PREFIX } from './utils';
+import { GC, isFontIconURI, isDataURI, isFileOrResourcePath, executeOnMainThread, mainThreadify, isMainThread, dispatchToMainThread, queueMacrotask, releaseNativeObject, getModuleName, openFile, openUrl, isRealDevice, layout, ad as androidUtils, iOSNativeHelper as iosUtils, Source, RESOURCE_PREFIX, FILE_PREFIX } from './utils';
 import { ClassInfo, getClass, getBaseClasses, getClassInfo, isBoolean, isDefined, isFunction, isNullOrUndefined, isNumber, isObject, isString, isUndefined, toUIString, verifyCallback } from './utils/types';
 
 export const Utils = {
@@ -124,6 +124,7 @@ export const Utils = {
 	mainThreadify,
 	isMainThread,
 	dispatchToMainThread,
+	queueMacrotask,
 	releaseNativeObject,
 
 	getModuleName,

diff --git a/packages/core/utils/index.d.ts b/packages/core/utils/index.d.ts
@@ -1,6 +1,7 @@
 import { dip, px } from '../ui/core/view';
 
 export * from './mainthread-helper';
+export * from './macrotask-scheduler';
 export { Source } from './debug';
 
 export * from './native-helper';
@@ -192,6 +193,12 @@ export function GC();
  */
 export function releaseNativeObject(object: any /*java.lang.Object | NSObject*/);
 
+/**
+ * Queues the passed function to be ran in a macroTask
+ * @param task the function to execute as a macroTask
+ */
+export function queueMacrotask(task: () => void): void;
+
 /**
  * Checks if the current thread is the main thread. Directly calls the passed function
  * if it is, or dispatches it to the main thread otherwise.

diff --git a/packages/core/utils/macrotask-scheduler.d.ts b/packages/core/utils/macrotask-scheduler.d.ts
@@ -0,0 +1,5 @@
+/**
+ * Queues the passed function to be ran in a macroTask
+ * @param task the function to execute as a macroTask
+ */
+export function queueMacrotask(task: () => void): void;
diff --git a/packages/core/utils/macrotask-scheduler.ts b/packages/core/utils/macrotask-scheduler.ts
@@ -0,0 +1,27 @@
+import { Trace } from 'trace';
+import { dispatchToMainThread } from './mainthread-helper';
+
+let scheduled = false;
+let macroTaskQueue: Array<() => void> = [];
+
+function drainMacrotaskQueue() {
+	const currentQueue = macroTaskQueue;
+	macroTaskQueue = [];
+	scheduled = false;
+	currentQueue.forEach((task) => {
+		try {
+			task();
+		} catch (err) {
+			const msg = err ? err.stack || err : err;
+			Trace.write(`Error in macroTask: ${msg}`, Trace.categories.Error, Trace.messageType.error);
+		}
+	});
+}
+
+export function queueMacrotask(task: () => void): void {
+	macroTaskQueue.push(task);
+	if (!scheduled) {
+		scheduled = true;
+		dispatchToMainThread(drainMacrotaskQueue);
+	}
+}
diff --git a/packages/core/utils/utils-common.ts b/packages/core/utils/utils-common.ts
@@ -5,6 +5,7 @@ import * as layout from './layout-helper';
 
 export { layout };
 export * from './mainthread-helper';
+export * from './macrotask-scheduler';
 
 export const RESOURCE_PREFIX = 'res://';
 export const FILE_PREFIX = 'file:///';