Move client/{base, observable, layout, touch, util, view} to samples/ui_lib .

client/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.
-
-typedef void AnimationCallback(num currentTime);
-
-class CallbackData {
-  final AnimationCallback callback;
-  final num minTime;
-  int id;
-
-  static int _nextId;
-
-  bool ready(num time) => minTime === null || minTime <= time;
-
-  CallbackData(this.callback, this.minTime) {
-    // TODO(jacobr): static init needs cleanup, see http://b/4161827
-    if (_nextId === null) {
-      _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.
- */
-// TODO(jacobr): use window.requestAnimationFrame when it is available and
-// 60fps for the current browser.
-class AnimationScheduler {
-  static final FRAMES_PER_SECOND = 60;
-  static final MS_PER_FRAME = 1000 ~/ FRAMES_PER_SECOND;
-  static final 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.
-      final element = new Element.tag('div');
-      document.body.nodes.add(element);
-      _safariHackStyle = element.style;
-      _safariHackStyle.position = 'absolute';
-    }
-  }
-
-  /**
-   * Cancel the pending callback matching the specified [id].
-   * This is not heavily optimized as typically users don't cancel animation
-   * frames.
-   */
-  void cancelRequestAnimationFrame(int id) {
-    _callbacks = _callbacks.filter((CallbackData e) => e.id != id);
-  }
-
-  /**
-   * Schedule [callback] to execute at the next animation frame that occurs
-   * at or after [minTime].  If [minTime] is not specified, the first available
-   * animation frame is used.  Returns an id that can be used to cancel the
-   * pending callback.
-   */
-  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) {
-      _setupInterval();
-    }
-  }
-
-  void _setupInterval() {
-    // Assert that we never schedule multiple frames at once.
-    assert(_intervalId === null);
-    if (USE_INTERVALS) {
-      _intervalId = window.setInterval(_step, MS_PER_FRAME);
-    } else {
-      if (_webkitAnimationFrameMaybeAvailable) {
-        try {
-          // TODO(jacobr): passing in document should not be required.
-          _intervalId = window.webkitRequestAnimationFrame(
-              (int ignored) { _step(); }, document);
-              // TODO(jacobr) fix this odd type error.
-        } catch (var e) {
-          _webkitAnimationFrameMaybeAvailable = false;
-        }
-      }
-      if (!_webkitAnimationFrameMaybeAvailable) {
-        _intervalId = window.setTimeout(() { _step(); }, MS_PER_FRAME);
-      }
-    }
-  }
-
-  void _step() {
-    if (_callbacks.isEmpty()) {
-      // Cancel the interval on the first frame where there aren't actually
-      // any available callbacks.
-      assert(_intervalId != null);
-      if (USE_INTERVALS) {
-        window.clearInterval(_intervalId);
-      }
-      _intervalId = null;
-    } else if (USE_INTERVALS == false) {
-      _intervalId = null;
-      _setupInterval();
-    }
-    int numRemaining = 0;
-    int minTime = new Date.now().value + MS_PER_FRAME;
-
-    int len = _callbacks.length;
-    for (final callback in _callbacks) {
-      if (!callback.ready(minTime)) {
-        numRemaining++;
-      }
-    }
-
-    if (numRemaining == len) {
-      // TODO(jacobr): we could be more clever about this case if delayed
-      // requests really become the main use case...
-      return;
-    }
-    // Some callbacks need to be executed.
-    final currentCallbacks = _callbacks;
-    _callbacks = new List<CallbackData>();
-
-    for (final callbackData in currentCallbacks) {
-      if (callbackData.ready(minTime)) {
-        try {
-          (callbackData.callback)(minTime);
-        } catch (var e) {
-          final msg = e.toString();
-          print('Suppressed exception ${msg} triggered by callback');
-        }
-      } else {
-        _callbacks.add(callbackData);
-      }
-    }
-
-    _frameCount++;
-    if (_isMobileSafari) {
-      // Hack to work around an iOS bug where sometimes animations do not
-      // render if only webkit transforms were modified.
-      // TODO(jacobr): find a cleaner workaround.
-      int offset = _frameCount % 2;
-      _safariHackStyle.left = '${offset}px';
-    }
-  }
-}