Add zone task support for request-anim.

tools/dom/templates/html/impl/impl_Window.darttemplate

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of $LIBRARYNAME;
 
+typedef void RemoveFrameRequestMapping(int id);
+
+/**
+ * The task object representing animation-frame requests.
+ *
+ * For historical reasons, [Window.requestAnimationFrame] returns an integer
+ * to users. However, zone tasks must be unique objects, and an integer can
+ * therefore not be used as task object. The [Window] class thus keeps a mapping
+ * from the integer ID to the corresponding task object. All zone related
+ * operations work on this task object, whereas users of
+ * [Window.requestAnimationFrame] only see the integer ID.
+ *
+ * Since this mapping takes up space, it must be removed as soon as the
+ * animation-frame task has triggered. The default implementation does this
+ * automatically, but intercepted implementations of `requestAnimationFrame`
+ * must ensure to call the [AnimationFrameTask.removeMapping]
+ * function that is provided in the task specification.
+ */
+abstract class AnimationFrameTask {
+  /** The ID that is returned to users. */
+  int get id;
+
+  /** The function that is invoked when the user cancels the request. */

[Lasse Reichstein Nielsen, 2016/06/29 09:22:12]

-> A function which
and consider: when -> if 

Maybe say why it is exposed? A custom or mock implementation may intercept this
call. (I guess that's why it's here).

[floitsch, 2016/06/30 19:42:49]

Done.

+  void cancel(Window window);
+
+  /** The zone in which the task should run. */

[Lasse Reichstein Nielsen, 2016/06/29 09:22:12]

should -> will

[floitsch, 2016/06/30 19:42:49]

Done.

+  Zone get zone;
+
+  /**
+   * Maps animation-frame request IDs to their task objects.
+   */
+  static final Map<int, _AnimationFrameTask> _tasks = {};
+
+  /**
+   * The function that should be invoked by user-implemented animation-frame

[Lasse Reichstein Nielsen, 2016/06/29 09:22:12]

-> A function which must ...

[floitsch, 2016/06/30 19:42:49]

Reworded.

+   * tasks, before running [callback].
+   *
+   * See [AnimationFrameTask].
+   */
+  static void removeMapping(int id) {
+    _tasks.remove(id);
+  }
+}
+
+class _AnimationFrameTask implements AnimationFrameTask {
+  final int id;
+  final Zone zone;
+  final FrameRequestCallback _callback;
+
+  _AnimationFrameTask(this.id, this.zone, this._callback);
+
+  void cancel(Window window) {
+    window._cancelAnimationFrame(this.id);
+  }
+}
+
+/**
+ * The task specification for an animation-frame request.

[Lasse Reichstein Nielsen, 2016/06/29 09:22:12]

Is there anything more to say about this class? Perhaps when it's used or who
will use it.
Otherwise it's just repeating the name.

[floitsch, 2016/06/30 19:42:49]

I added an "experimental" note.

+ */
+class AnimationFrameRequestSpecification implements TaskSpecification {
+  /**
+   * The window on which [Window.requestAnimationFrame] was invoked.
+   */
+  final Window window;
+
+  /**
+   * The callback that should be executed when the animation-frame is ready.

[Lasse Reichstein Nielsen, 2016/06/29 09:22:12]

should -> will

[floitsch, 2016/06/30 19:42:49]

-> is.
done.

+   *
+   * Note that the callback hasn't been registered in any zone yet.

[Lasse Reichstein Nielsen, 2016/06/29 09:22:12]

"yet" isn't a good word for a final property which can be retained forever.

Maybe "hasn't been registered in a zone when this object is passed to the
`Zone.createTask` implementation".

[floitsch, 2016/06/30 19:42:49]

Reworded. The important thing is, that the create function receives an
unregistered function.

+   */
+  final FrameRequestCallback callback;
+
+  AnimationFrameRequestSpecification(this.window, this.callback);
+
+  String get name => "dart.html.request-animation-frame";
+  bool get isOneShot => true;
+}
+
 @DocsEditable()
 $if DART2JS
 $(ANNOTATIONS)@Native("Window,DOMWindow")
 $(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 $else
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS {
 $endif
 
   /**
    * Returns a Future that completes just before the window is about to
    * repaint so the user can draw an animation frame.
    *
    * If you need to later cancel this animation, use [requestAnimationFrame]
    * instead.
    *
    * The [Future] completes to a timestamp that represents a floating
    * point value of the number of milliseconds that have elapsed since the page
    * started to load (which is also the timestamp at this call to
    * animationFrame).
    *
    * Note: The code that runs when the future completes should call
    * [animationFrame] again for the animation to continue.
    */
   Future<num> get animationFrame {
     var completer = new Completer<num>.sync();
-    requestAnimationFrame((time) {
-      completer.complete(time);
-    });
+    requestAnimationFrame(completer.complete);
     return completer.future;
   }
 
 $if DART2JS
   /**
    * The newest document in this window.
    *
    * ## Other resources
    *
    * * [Loading web
@@ skipping 63 matching lines @@
    * request. This value only needs to be saved if you intend to call
    * [cancelAnimationFrame] so you can specify the particular animation to
    * cancel.
    *
    * Note: The supplied [callback] needs to call [requestAnimationFrame] again
    * for the animation to continue.
    */
   @DomName('Window.requestAnimationFrame')
   int requestAnimationFrame(FrameRequestCallback callback) {
     _ensureRequestAnimationFrame();
-    return _requestAnimationFrame(_wrapZone/*<dynamic, num>*/(callback));
+    if (identical(Zone.current, Zone.ROOT)) {
+      return _requestAnimationFrame(callback);
+    }
+    var spec = new AnimationFrameRequestSpecification(this, callback);
+    var task = Zone.current.createTask/*<AnimationFrameTask>*/(
+        _createAnimationFrameTask, spec);
+    AnimationFrameTask._tasks[task.id] = task;
+    return task.id;
+  }
+
+  static _AnimationFrameTask _createAnimationFrameTask(
+      AnimationFrameRequestSpecification spec, Zone zone) {
+    var task;
+    var id = spec.window._requestAnimationFrame((num time) {
+      AnimationFrameTask.removeMapping(task.id);
+      zone.runTask(_runAnimationFrame, task, time);
+    });
+    var callback = zone.registerUnaryCallback(spec.callback);
+    task = new _AnimationFrameTask(id, zone, callback);
+    return task;
+  }
+
+  static void _runAnimationFrame(_AnimationFrameTask task, num time) {
+    task._callback(time);
   }
 
   /**
    * Cancels an animation frame request.
    *
    * ## Other resources
    *
    * * [Window.cancelAnimationFrame](https://developer.mozilla.org/en-US/docs/Web/API/Window.cancelAnimationFrame)
    *   from MDN.
    */
   void cancelAnimationFrame(int id) {
     _ensureRequestAnimationFrame();
-    _cancelAnimationFrame(id);
+    var task = AnimationFrameTask._tasks.remove(id);
+    if (task == null) {
+      // Assume that the animation frame request wasn't intercepted by a zone.
+      _cancelAnimationFrame(id);
+      return;
+    }
+    task.cancel(this);
   }
 
   @JSName('requestAnimationFrame')
   int _requestAnimationFrame(FrameRequestCallback callback) native;
 
   @JSName('cancelAnimationFrame')
   void _cancelAnimationFrame(int id) native;
 
   _ensureRequestAnimationFrame() {
     if (JS('bool',
@@ skipping 233 matching lines @@
       {bool useCapture: false}) {
 $if DART2JS
     // Specify the generic type for _ElementEventStreamImpl only in dart2js to
     // avoid checked mode errors in dartium.
     return new _ElementListEventStreamImpl<BeforeUnloadEvent>(e, _eventType, useCapture);
 $else
     return new _ElementListEventStreamImpl(e, _eventType, useCapture);
 $endif
   }
 }