Combine window.setTimeout/setInterval with Timer and Timer.repeating. Also

samples/swarm/swarm_ui_lib/base/AnimationScheduler.dart

 // Copyright (c) 2011, 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 base;
 
 typedef void AnimationCallback(num currentTime);
 
 class CallbackData {
   final AnimationCallback callback;
@@ skipping 10 matching lines @@
       _nextId = 1;
     }
     id = _nextId++;
   }
 }
 
 /**
  * Animation scheduler implementing the functionality provided by
  * [:window.requestAnimationFrame:] for platforms that do not support it
  * or support it badly.  When multiple UI components are animating at once,
- * this approach yields superior performance to calling setTimeout directly as
- * all pieces of the UI will animate at the same time resulting in fewer
- * layouts.
+ * this approach yields superior performance to calling setTimeout/Timer
+ * directly as all pieces of the UI will animate at the same time resulting in
+ * fewer layouts.
  */
 // TODO(jacobr): use window.requestAnimationFrame when it is available and
 // 60fps for the current browser.
 class AnimationScheduler {
   static const FRAMES_PER_SECOND = 60;
   static const MS_PER_FRAME = 1000 ~/ FRAMES_PER_SECOND;
   static const USE_INTERVALS = false;
 
   /** List of callbacks to be executed next animation frame. */
   List<CallbackData> _callbacks;
-  int _intervalId;
   bool _isMobileSafari = false;
   CssStyleDeclaration _safariHackStyle;
   int _frameCount = 0;
   bool _webkitAnimationFrameMaybeAvailable = true;
 
   AnimationScheduler()
     : _callbacks = new List<CallbackData>() {
     if (_isMobileSafari) {
       // TODO(jacobr): find a better workaround for the issue that 3d transforms
       // sometimes don't render on iOS without forcing a layout.
@@ skipping 22 matching lines @@
   int requestAnimationFrame(AnimationCallback callback,
                             [Element element = null,
                              num minTime = null]) {
     final callbackData = new CallbackData(callback, minTime);
     _requestAnimationFrameHelper(callbackData);
     return callbackData.id;
   }
 
   void _requestAnimationFrameHelper(CallbackData callbackData) {
     _callbacks.add(callbackData);
-    if (_intervalId == null) {
+    if (_timer == null) {

[blois, 2013/02/13 03:09:24]

Is _timer declared somewhere?

[Emily Fortuna, 2013/02/13 20:19:44]

Done.

       _setupInterval();
     }
   }
 
   void _setupInterval() {
     // Assert that we never schedule multiple frames at once.
-    assert(_intervalId == null);
+    assert(__timer == null);
     if (USE_INTERVALS) {
-      _intervalId = window.setInterval(_step, MS_PER_FRAME);
+      _timer = new Timer.repeating(const Duration(milliseconds: MS_PER_FRAME),
+          _step);

[floitsch, 2013/02/13 10:03:07]

The original code doesn't look like it's repeating.

Timer.repeating takes a function with a Timer argument.
Please file a bug if you think that's not a good idea.

[Emily Fortuna, 2013/02/13 20:19:44]

setInterval fires repeatedly:
https://developer.mozilla.org/en-US/docs/DOM/window.setInterval 

     } else {
       if (_webkitAnimationFrameMaybeAvailable) {
         try {
           // TODO(jacobr): passing in document should not be required.
-          _intervalId = window.webkitRequestAnimationFrame(
+          window.webkitRequestAnimationFrame(
               (int ignored) { _step(); });
               // TODO(jacobr) fix this odd type error.
         } catch (e) {
           _webkitAnimationFrameMaybeAvailable = false;
         }
       }
       if (!_webkitAnimationFrameMaybeAvailable) {
-        _intervalId = window.setTimeout(() { _step(); }, MS_PER_FRAME);
+        _timer = new Timer(const Duration(milliseconds: MS_PER_FRAME),
+            () { _step(); });

[floitsch, 2013/02/13 10:03:07]

remove the closure. Just "_step".

[Emily Fortuna, 2013/02/13 20:19:44]

Done.

       }
     }
   }
 
   void _step() {
     if (_callbacks.isEmpty) {
       // Cancel the interval on the first frame where there aren't actually
       // any available callbacks.
-      assert(_intervalId != null);
+      assert(_timer != null);
       if (USE_INTERVALS) {
-        window.clearInterval(_intervalId);
+        _timer.cancel();
       }
-      _intervalId = null;
+      _timer = null;
     } else if (USE_INTERVALS == false) {
-      _intervalId = null;
+      _timer = null;
       _setupInterval();
     }
     int numRemaining = 0;
     int minTime = new DateTime.now().millisecondsSinceEpoch + MS_PER_FRAME;
 
     int len = _callbacks.length;
     for (final callback in _callbacks) {
       if (!callback.ready(minTime)) {
         numRemaining++;
       }
@@ skipping 24 matching lines @@
     _frameCount++;
     if (_isMobileSafari) {
       // Hack to work around an iOS bug where sometimes animations do not
       // render if only webkit transforms were modified.
       // TODO(jacobr): find a cleaner workaround.
       int offset = _frameCount % 2;
       _safariHackStyle.left = '${offset}px';
     }
   }
 }