Remove Performance and AnimatedValue

This patch removes Performance and AnimationValue now that we've ported the
framework over to AnimationController and Tween. This patch also cleans up the
names of the AnimationController classes now that they don't have to avoid
conflicts with the old animation API. Specifically, I've made the following
renames:

 * Animated -> Animation
 * Evaluatable -> Animatable
 * PerformanceStatus -> AnimationStatus

This patch is just renames and moving code around. There aren't any changes in
behavior.

examples/material_gallery/lib/demo/progress_indicator_demo.dart

@@ -21,13 +21,13 @@ class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo> {
       parent: controller,
       curve: new Interval(0.0, 0.9, curve: Curves.ease),
       reverseCurve: Curves.ease
-    )..addStatusListener((PerformanceStatus status) {
-      if (status == PerformanceStatus.dismissed || status == PerformanceStatus.completed)
+    )..addStatusListener((AnimationStatus status) {
+      if (status == AnimationStatus.dismissed || status == AnimationStatus.completed)
         reverseValueAnimationDirection();
     });
   }
 
-  Animated<double> animation;
+  Animation<double> animation;
   AnimationController controller;
 
   void handleTap() {

examples/widgets/smooth_resize.dart

@@ -33,10 +33,10 @@ class CardTransition extends StatelessComponent {
   });
 
   final Widget child;
-  final Animated<double> animation;
-  final Evaluatable<double> x;
-  final Evaluatable<double> opacity;
-  final Evaluatable<double> scale;
+  final Animation<double> animation;
+  final Animatable<double> x;
+  final Animatable<double> opacity;
+  final Animatable<double> scale;
 
   Widget build(BuildContext context) {
     return new AnimatedBuilder(
@@ -63,7 +63,7 @@ class SmoothBlockState extends State<SmoothBlock> {
 
   double _height = 100.0;
 
-  Widget _handleEnter(Animated<double> animation, Widget child) {
+  Widget _handleEnter(Animation<double> animation, Widget child) {
     return new CardTransition(
       x: new Tween<double>(begin: -200.0, end: 0.0),
       opacity: new Tween<double>(begin: 0.0, end: 1.0),
@@ -73,7 +73,7 @@ class SmoothBlockState extends State<SmoothBlock> {
     );
   }
 
-  Widget _handleExit(Animated<double> animation, Widget child) {
+  Widget _handleExit(Animation<double> animation, Widget child) {
     return new CardTransition(
       x: new Tween<double>(begin: 0.0, end: 200.0),
       opacity: new Tween<double>(begin: 1.0, end: 0.0),

packages/flutter/lib/animation.dart

@@ -7,13 +7,13 @@
 /// This library depends only on core Dart libraries and the `newton` package.
 library animation;
 
-export 'src/animation/animated_value.dart';
+export 'src/animation/animation.dart';
+export 'src/animation/animation_controller.dart';
 export 'src/animation/animations.dart';
 export 'src/animation/clamped_simulation.dart';
 export 'src/animation/curves.dart';
 export 'src/animation/forces.dart';
 export 'src/animation/listener_helpers.dart';
-export 'src/animation/performance.dart';
 export 'src/animation/scroll_behavior.dart';
 export 'src/animation/simulation_stepper.dart';
 export 'src/animation/ticker.dart';

packages/flutter/lib/src/animation/animated_value.dart

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'dart:ui' show Color, Size, Rect;
-
-import 'curves.dart';
-
-/// The direction in which an animation is running.
-enum AnimationDirection {
-  /// The animation is running from beginning to end.
-  forward,
-
-  /// The animation is running backwards, from end to beginning.
-  reverse
-}
-
-/// An interface describing a variable that changes as an animation progresses.
-///
-/// Animatable objects, by convention, must be cheap to create. This allows them
-/// to be used in build functions in Widgets.
-abstract class Animatable {
-  // TODO(ianh): replace mentions of this class with just mentioning AnimatedValue directly
-  /// Update the variable to a given time in an animation that is running in the given direction
-  void setProgress(double t, AnimationDirection direction);
-}
-
-/// An animated variable with a concrete type.
-class AnimatedValue<T extends dynamic> implements Animatable {
-  AnimatedValue(this.begin, { this.end, this.curve, this.reverseCurve }) {
-    value = begin;
-  }
-
-  /// The current value of this variable.
-  T value;
-
-  /// The value this variable has at the beginning of the animation.
-  T begin;
-
-  /// The value this variable has at the end of the animation.
-  T end;
-
-  /// Returns the value this variable has at the given animation clock value.
-  T lerp(double t) => begin + (end - begin) * t;
-
-  /// The curve to use in the forward direction.
-  Curve curve;
-
-  /// The curve to use in the reverse direction.
-  ///
-  /// If this field is null, uses [curve] in both directions.
-  Curve reverseCurve;
-
-  Curve _getActiveCurve(AnimationDirection direction) {
-    if (direction == AnimationDirection.forward || reverseCurve == null)
-      return curve;
-    return reverseCurve;
-  }
-
-  double transform(double t, AnimationDirection direction) {
-    Curve activeCurve = _getActiveCurve(direction);
-    if (activeCurve == null)
-      return t;
-    if (t == 0.0 || t == 1.0) {
-      assert(activeCurve.transform(t).round() == t);
-      return t;
-    }
-    return activeCurve.transform(t);
-  }
-
-  /// Updates the value of this variable according to the given animation clock
-  /// value and direction.
-  void setProgress(double t, AnimationDirection direction) {
-    if (end != null) {
-      t = transform(t, direction);
-      if (t == 0.0)
-        value = begin;
-      else if (t == 1.0)
-        value = end;
-      else
-        value = lerp(t);
-    }
-  }
-
-  String toString() => 'AnimatedValue(begin=$begin, end=$end, value=$value)';
-}
-
-/// An animated variable containing a color.
-///
-/// This class specializes the interpolation of AnimatedValue<Color> to be
-/// appropriate for colors.
-class AnimatedColorValue extends AnimatedValue<Color> {
-  AnimatedColorValue(Color begin, { Color end, Curve curve, Curve reverseCurve })
-    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
-
-  Color lerp(double t) => Color.lerp(begin, end, t);
-}
-
-/// An animated variable containing a size.
-///
-/// This class specializes the interpolation of AnimatedValue<Size> to be
-/// appropriate for rectangles.
-class AnimatedSizeValue extends AnimatedValue<Size> {
-  AnimatedSizeValue(Size begin, { Size end, Curve curve, Curve reverseCurve })
-    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
-
-  Size lerp(double t) => Size.lerp(begin, end, t);
-}
-
-/// An animated variable containing a rectangle.
-///
-/// This class specializes the interpolation of AnimatedValue<Rect> to be
-/// appropriate for rectangles.
-class AnimatedRectValue extends AnimatedValue<Rect> {
-  AnimatedRectValue(Rect begin, { Rect end, Curve curve, Curve reverseCurve })
-    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
-
-  Rect lerp(double t) => Rect.lerp(begin, end, t);
-}
-
-/// An animated variable containing a int.
-class AnimatedIntValue extends AnimatedValue<int> {
-  AnimatedIntValue(int begin, { int end, Curve curve, Curve reverseCurve })
-    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
-
-  // The inherited lerp() function doesn't work with ints because it multiplies
-  // the begin and end types by a double, and int * double returns a double.
-  int lerp(double t) => (begin + (end - begin) * t).round();
-}

packages/flutter/lib/src/animation/animation.dart

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:ui' show Color, Size, Rect, VoidCallback, lerpDouble;
+
+/// The direction in which an animation is running.
+enum AnimationDirection {
+  /// The animation is running from beginning to end.
+  forward,
+
+  /// The animation is running backwards, from end to beginning.
+  reverse
+}
+
+/// The status of an animation
+enum AnimationStatus {
+  /// The animation is stopped at the beginning
+  dismissed,
+
+  /// The animation is running from beginning to end
+  forward,
+
+  /// The animation is running backwards, from end to beginning
+  reverse,
+
+  /// The animation is stopped at the end
+  completed,
+}
+
+typedef void AnimationStatusListener(AnimationStatus status);
+
+abstract class Animation<T> {
+  const Animation();
+
+  /// Calls the listener every time the value of the animation changes.
+  void addListener(VoidCallback listener);
+  /// Stop calling the listener every time the value of the animation changes.
+  void removeListener(VoidCallback listener);
+  /// Calls listener every time the status of the animation changes.
+  void addStatusListener(AnimationStatusListener listener);
+  /// Stops calling the listener every time the status of the animation changes.
+  void removeStatusListener(AnimationStatusListener listener);
+
+  /// The current status of this animation.
+  AnimationStatus get status;
+
+  /// The current direction of the animation.
+  AnimationDirection get direction;
+
+  /// The current value of the animation.
+  T get value;
+
+  /// Whether this animation is stopped at the beginning.
+  bool get isDismissed => status == AnimationStatus.dismissed;
+
+  /// Whether this animation is stopped at the end.
+  bool get isCompleted => status == AnimationStatus.completed;
+
+  String toString() {
+    return '$runtimeType(${toStringDetails()})';
+  }
+  String toStringDetails() {
+    assert(status != null);
+    assert(direction != null);
+    String icon;
+    switch (status) {
+      case AnimationStatus.forward:
+        icon = '\u25B6'; // >
+        break;
+      case AnimationStatus.reverse:
+        icon = '\u25C0'; // <
+        break;
+      case AnimationStatus.completed:
+        switch (direction) {
+          case AnimationDirection.forward:
+            icon = '\u23ED'; // >>|
+            break;
+          case AnimationDirection.reverse:
+            icon = '\u29CF'; // <|
+            break;
+        }
+        break;
+      case AnimationStatus.dismissed:
+        switch (direction) {
+          case AnimationDirection.forward:
+            icon = '\u29D0'; // |>
+            break;
+          case AnimationDirection.reverse:
+            icon = '\u23EE'; // |<<
+            break;
+        }
+        break;
+    }
+    assert(icon != null);
+    return '$icon';
+  }
+}

packages/flutter/lib/src/animation/animation_controller.dart

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:ui' show Color, Size, Rect, VoidCallback, lerpDouble;
+
+import 'package:newton/newton.dart';
+
+import 'animation.dart';
+import 'forces.dart';
+import 'listener_helpers.dart';
+import 'simulation_stepper.dart';
+
+class AnimationController extends Animation<double>
+  with EagerListenerMixin, LocalPerformanceListenersMixin, LocalPerformanceStatusListenersMixin {
+  AnimationController({ this.duration, double value, this.debugLabel }) {
+    _timeline = new SimulationStepper(_tick);
+    if (value != null)
+      _timeline.value = value.clamp(0.0, 1.0);
+  }
+
+  /// A label that is used in the [toString] output. Intended to aid with
+  /// identifying animation controller instances in debug output.
+  final String debugLabel;
+
+  /// Returns a [Animated<double>] for this animation controller,
+  /// so that a pointer to this object can be passed around without
+  /// allowing users of that pointer to mutate the AnimationController state.
+  Animation<double> get view => this;
+
+  /// The length of time this animation should last.
+  Duration duration;
+
+  SimulationStepper _timeline;
+  AnimationDirection get direction => _direction;
+  AnimationDirection _direction = AnimationDirection.forward;
+
+  /// The progress of this animation along the timeline.
+  ///
+  /// Note: Setting this value stops the current animation.
+  double get value => _timeline.value.clamp(0.0, 1.0);
+  void set value(double t) {
+    stop();
+    _timeline.value = t.clamp(0.0, 1.0);
+    _checkStatusChanged();
+  }
+
+  /// Whether this animation is currently animating in either the forward or reverse direction.
+  bool get isAnimating => _timeline.isAnimating;
+
+  AnimationStatus get status {
+    if (!isAnimating && value == 1.0)
+      return AnimationStatus.completed;
+    if (!isAnimating && value == 0.0)
+      return AnimationStatus.dismissed;
+    return _direction == AnimationDirection.forward ?
+        AnimationStatus.forward :
+        AnimationStatus.reverse;
+  }
+
+  /// Starts running this animation forwards (towards the end).
+  Future forward() => play(AnimationDirection.forward);
+
+  /// Starts running this animation in reverse (towards the beginning).
+  Future reverse() => play(AnimationDirection.reverse);
+
+  /// Starts running this animation in the given direction.
+  Future play(AnimationDirection direction) {
+    _direction = direction;
+    return resume();
+  }
+
+  /// Resumes this animation in the most recent direction.
+  Future resume() {
+    return _animateTo(_direction == AnimationDirection.forward ? 1.0 : 0.0);
+  }
+
+  /// Stops running this animation.
+  void stop() {
+    _timeline.stop();
+  }
+
+  /// Releases any resources used by this object.
+  ///
+  /// Same as stop().
+  void dispose() {
+    stop();
+  }
+
+  ///
+  /// Flings the timeline with an optional force (defaults to a critically
+  /// damped spring) and initial velocity. If velocity is positive, the
+  /// animation will complete, otherwise it will dismiss.
+  Future fling({double velocity: 1.0, Force force}) {
+    force ??= kDefaultSpringForce;
+    _direction = velocity < 0.0 ? AnimationDirection.reverse : AnimationDirection.forward;
+    return _timeline.animateWith(force.release(value, velocity));
+  }
+
+  /// Starts running this animation in the forward direction, and
+  /// restarts the animation when it completes.
+  Future repeat({ double min: 0.0, double max: 1.0, Duration period }) {
+    period ??= duration;
+    return _timeline.animateWith(new _RepeatingSimulation(min, max, period));
+  }
+
+  AnimationStatus _lastStatus = AnimationStatus.dismissed;
+  void _checkStatusChanged() {
+    AnimationStatus currentStatus = status;
+    if (currentStatus != _lastStatus)
+      notifyStatusListeners(status);
+    _lastStatus = currentStatus;
+  }
+
+  Future _animateTo(double target) {
+    Duration remainingDuration = duration * (target - _timeline.value).abs();
+    _timeline.stop();
+    if (remainingDuration == Duration.ZERO)
+      return new Future.value();
+    return _timeline.animateTo(target, duration: remainingDuration);
+  }
+
+  void _tick(double t) {
+    notifyListeners();
+    _checkStatusChanged();
+  }
+
+  String toStringDetails() {
+    String paused = _timeline.isAnimating ? '' : '; paused';
+    String label = debugLabel == null ? '' : '; for $debugLabel';
+    String more = '${super.toStringDetails()} ${value.toStringAsFixed(3)}';
+    return '$more$paused$label';
+  }
+}
+
+class _RepeatingSimulation extends Simulation {
+  _RepeatingSimulation(this.min, this.max, Duration period)
+    : _periodInSeconds = period.inMicroseconds / Duration.MICROSECONDS_PER_SECOND {
+    assert(_periodInSeconds > 0.0);
+  }
+
+  final double min;
+  final double max;
+
+  final double _periodInSeconds;
+
+  double x(double timeInSeconds) {
+    assert(timeInSeconds >= 0.0);
+    final double t = (timeInSeconds / _periodInSeconds) % 1.0;
+    return lerpDouble(min, max, t);
+  }
+
+  double dx(double timeInSeconds) => 1.0;
+
+  bool isDone(double timeInSeconds) => false;
+}

packages/flutter/lib/src/animation/animations.dart

@@ -4,56 +4,81 @@
 
 import 'dart:ui' show VoidCallback;
 
-import 'animated_value.dart';
+import 'animation.dart';
+import 'curves.dart';
 import 'listener_helpers.dart';
-import 'tween.dart';
 
-class AlwaysCompleteAnimation extends Animated<double> {
+class AlwaysCompleteAnimation extends Animation<double> {
   const AlwaysCompleteAnimation();
 
   void addListener(VoidCallback listener) { }
   void removeListener(VoidCallback listener) { }
-  void addStatusListener(PerformanceStatusListener listener) { }
-  void removeStatusListener(PerformanceStatusListener listener) { }
-  PerformanceStatus get status => PerformanceStatus.completed;
+  void addStatusListener(AnimationStatusListener listener) { }
+  void removeStatusListener(AnimationStatusListener listener) { }
+  AnimationStatus get status => AnimationStatus.completed;
   AnimationDirection get direction => AnimationDirection.forward;
   double get value => 1.0;
 }
 
 const AlwaysCompleteAnimation kAlwaysCompleteAnimation = const AlwaysCompleteAnimation();
 
-class AlwaysDismissedAnimation extends Animated<double> {
+class AlwaysDismissedAnimation extends Animation<double> {
   const AlwaysDismissedAnimation();
 
   void addListener(VoidCallback listener) { }
   void removeListener(VoidCallback listener) { }
-  void addStatusListener(PerformanceStatusListener listener) { }
-  void removeStatusListener(PerformanceStatusListener listener) { }
-  PerformanceStatus get status => PerformanceStatus.dismissed;
+  void addStatusListener(AnimationStatusListener listener) { }
+  void removeStatusListener(AnimationStatusListener listener) { }
+  AnimationStatus get status => AnimationStatus.dismissed;
   AnimationDirection get direction => AnimationDirection.forward;
   double get value => 0.0;
 }
 
 const AlwaysDismissedAnimation kAlwaysDismissedAnimation = const AlwaysDismissedAnimation();
 
-class ProxyAnimation extends Animated<double>
+class AlwaysStoppedAnimation extends Animation<double> {
+  const AlwaysStoppedAnimation(this.value);
+
+  final double value;
+
+  void addListener(VoidCallback listener) { }
+  void removeListener(VoidCallback listener) { }
+  void addStatusListener(AnimationStatusListener listener) { }
+  void removeStatusListener(AnimationStatusListener listener) { }
+  AnimationStatus get status => AnimationStatus.forward;
+  AnimationDirection get direction => AnimationDirection.forward;
+}
+
+abstract class ProxyAnimatedMixin {
+  Animation<double> get parent;
+
+  void addListener(VoidCallback listener) => parent.addListener(listener);
+  void removeListener(VoidCallback listener) => parent.removeListener(listener);
+  void addStatusListener(AnimationStatusListener listener) => parent.addStatusListener(listener);
+  void removeStatusListener(AnimationStatusListener listener) => parent.removeStatusListener(listener);
+
+  AnimationStatus get status => parent.status;
+  AnimationDirection get direction => parent.direction;
+}
+
+class ProxyAnimation extends Animation<double>
   with LazyListenerMixin, LocalPerformanceListenersMixin, LocalPerformanceStatusListenersMixin {
-  ProxyAnimation([Animated<double> animation]) {
+  ProxyAnimation([Animation<double> animation]) {
     _masterAnimation = animation;
     if (_masterAnimation == null) {
-      _status = PerformanceStatus.dismissed;
+      _status = AnimationStatus.dismissed;
       _direction = AnimationDirection.forward;
       _value = 0.0;
     }
   }
 
-  PerformanceStatus _status;
+  AnimationStatus _status;
   AnimationDirection _direction;
   double _value;
 
-  Animated<double> get masterAnimation => _masterAnimation;
-  Animated<double> _masterAnimation;
-  void set masterAnimation(Animated<double> value) {
+  Animation<double> get masterAnimation => _masterAnimation;
+  Animation<double> _masterAnimation;
+  void set masterAnimation(Animation<double> value) {
     if (value == _masterAnimation)
       return;
     if (_masterAnimation != null) {
@@ -91,16 +116,16 @@ class ProxyAnimation extends Animated<double>
     }
   }
 
-  PerformanceStatus get status => _masterAnimation != null ? _masterAnimation.status : _status;
+  AnimationStatus get status => _masterAnimation != null ? _masterAnimation.status : _status;
   AnimationDirection get direction => _masterAnimation != null ? _masterAnimation.direction : _direction;
   double get value => _masterAnimation != null ? _masterAnimation.value : _value;
 }
 
-class ReverseAnimation extends Animated<double>
+class ReverseAnimation extends Animation<double>
   with LazyListenerMixin, LocalPerformanceStatusListenersMixin {
   ReverseAnimation(this.masterAnimation);
 
-  final Animated<double> masterAnimation;
+  final Animation<double> masterAnimation;
 
   void addListener(VoidCallback listener) {
     didRegisterListener();
@@ -119,20 +144,20 @@ class ReverseAnimation extends Animated<double>
     masterAnimation.removeStatusListener(_statusChangeHandler);
   }
 
-  void _statusChangeHandler(PerformanceStatus status) {
+  void _statusChangeHandler(AnimationStatus status) {
     notifyStatusListeners(_reverseStatus(status));
   }
 
-  PerformanceStatus get status => _reverseStatus(masterAnimation.status);
+  AnimationStatus get status => _reverseStatus(masterAnimation.status);
   AnimationDirection get direction => _reverseDirection(masterAnimation.direction);
   double get value => 1.0 - masterAnimation.value;
 
-  PerformanceStatus _reverseStatus(PerformanceStatus status) {
+  AnimationStatus _reverseStatus(AnimationStatus status) {
     switch (status) {
-      case PerformanceStatus.forward: return PerformanceStatus.reverse;
-      case PerformanceStatus.reverse: return PerformanceStatus.forward;
-      case PerformanceStatus.completed: return PerformanceStatus.dismissed;
-      case PerformanceStatus.dismissed: return PerformanceStatus.completed;
+      case AnimationStatus.forward: return AnimationStatus.reverse;
+      case AnimationStatus.reverse: return AnimationStatus.forward;
+      case AnimationStatus.completed: return AnimationStatus.dismissed;
+      case AnimationStatus.dismissed: return AnimationStatus.completed;
     }
   }
 
@@ -144,6 +169,64 @@ class ReverseAnimation extends Animated<double>
   }
 }
 
+class CurvedAnimation extends Animation<double> with ProxyAnimatedMixin {
+  CurvedAnimation({
+    this.parent,
+    this.curve: Curves.linear,
+    this.reverseCurve
+  }) {
+    assert(parent != null);
+    assert(curve != null);
+    parent.addStatusListener(_handleStatusChanged);
+  }
+
+  final Animation<double> parent;
+
+  /// The curve to use in the forward direction.
+  Curve curve;
+
+  /// The curve to use in the reverse direction.
+  ///
+  /// If this field is null, uses [curve] in both directions.
+  Curve reverseCurve;
+
+  /// The direction used to select the current curve.
+  ///
+  /// The curve direction is only reset when we hit the beginning or the end of
+  /// the timeline to avoid discontinuities in the value of any variables this
+  /// a animation is used to animate.
+  AnimationDirection _curveDirection;
+
+  void _handleStatusChanged(AnimationStatus status) {
+    switch (status) {
+      case AnimationStatus.dismissed:
+      case AnimationStatus.completed:
+        _curveDirection = null;
+        break;
+      case AnimationStatus.forward:
+        _curveDirection ??= AnimationDirection.forward;
+        break;
+      case AnimationStatus.reverse:
+        _curveDirection ??= AnimationDirection.reverse;
+        break;
+    }
+  }
+
+  double get value {
+    final bool useForwardCurve = reverseCurve == null || (_curveDirection ?? parent.direction) == AnimationDirection.forward;
+    Curve activeCurve = useForwardCurve ? curve : reverseCurve;
+
+    double t = parent.value;
+    if (activeCurve == null)
+      return t;
+    if (t == 0.0 || t == 1.0) {
+      assert(activeCurve.transform(t).round() == t);
+      return t;
+    }
+    return activeCurve.transform(t);
+  }
+}
+
 enum _TrainHoppingMode { minimize, maximize }
 
 /// This animation starts by proxying one animation, but can be given a
@@ -156,7 +239,7 @@ enum _TrainHoppingMode { minimize, maximize }
 /// listeners of its own, instead of shutting down when all its listeners are
 /// removed, it exposes a [dispose()] method. Call this method to shut this
 /// object down.
-class TrainHoppingAnimation extends Animated<double>
+class TrainHoppingAnimation extends Animation<double>
   with EagerListenerMixin, LocalPerformanceListenersMixin, LocalPerformanceStatusListenersMixin {
   TrainHoppingAnimation(this._currentTrain, this._nextTrain, { this.onSwitchedTrain }) {
     assert(_currentTrain != null);
@@ -178,15 +261,15 @@ class TrainHoppingAnimation extends Animated<double>
     assert(_mode != null);
   }
 
-  Animated<double> get currentTrain => _currentTrain;
-  Animated<double> _currentTrain;
-  Animated<double> _nextTrain;
+  Animation<double> get currentTrain => _currentTrain;
+  Animation<double> _currentTrain;
+  Animation<double> _nextTrain;
   _TrainHoppingMode _mode;
 
   VoidCallback onSwitchedTrain;
 
-  PerformanceStatus _lastStatus;
-  void _statusChangeHandler(PerformanceStatus status) {
+  AnimationStatus _lastStatus;
+  void _statusChangeHandler(AnimationStatus status) {
     assert(_currentTrain != null);
     if (status != _lastStatus) {
       notifyListeners();
@@ -195,7 +278,7 @@ class TrainHoppingAnimation extends Animated<double>
     assert(_lastStatus != null);
   }
 
-  PerformanceStatus get status => _currentTrain.status;
+  AnimationStatus get status => _currentTrain.status;
   AnimationDirection get direction => _currentTrain.direction;
 
   double _lastValue;

packages/flutter/lib/src/animation/listener_helpers.dart

@@ -4,22 +4,7 @@
 
 import 'dart:ui' show VoidCallback;
 
-/// The status of an animation
-enum PerformanceStatus {
-  /// The animation is stopped at the beginning
-  dismissed,
-
-  /// The animation is running from beginning to end
-  forward,
-
-  /// The animation is running backwards, from end to beginning
-  reverse,
-
-  /// The animation is stopped at the end
-  completed,
-}
-
-typedef void PerformanceStatusListener(PerformanceStatus status);
+import 'animation.dart';
 
 abstract class _ListenerMixin {
   void didRegisterListener();
@@ -71,18 +56,18 @@ abstract class LocalPerformanceListenersMixin extends _ListenerMixin {
 }
 
 abstract class LocalPerformanceStatusListenersMixin extends _ListenerMixin {
-  final List<PerformanceStatusListener> _statusListeners = <PerformanceStatusListener>[];
-  void addStatusListener(PerformanceStatusListener listener) {
+  final List<AnimationStatusListener> _statusListeners = <AnimationStatusListener>[];
+  void addStatusListener(AnimationStatusListener listener) {
     didRegisterListener();
     _statusListeners.add(listener);
   }
-  void removeStatusListener(PerformanceStatusListener listener) {
+  void removeStatusListener(AnimationStatusListener listener) {
     _statusListeners.remove(listener);
     didUnregisterListener();
   }
-  void notifyStatusListeners(PerformanceStatus status) {
-    List<PerformanceStatusListener> localListeners = new List<PerformanceStatusListener>.from(_statusListeners);
-    for (PerformanceStatusListener listener in localListeners)
+  void notifyStatusListeners(AnimationStatus status) {
+    List<AnimationStatusListener> localListeners = new List<AnimationStatusListener>.from(_statusListeners);
+    for (AnimationStatusListener listener in localListeners)
       listener(status);
   }
 }

packages/flutter/lib/src/material/bottom_sheet.dart

@@ -167,7 +167,7 @@ class _ModalBottomSheetRoute<T> extends PopupRoute<T> {
     return BottomSheet.createAnimationController();
   }
 
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
     return new _ModalBottomSheet(route: this);
   }
 }

packages/flutter/lib/src/material/dialog.dart

@@ -128,11 +128,11 @@ class _DialogRoute<T> extends PopupRoute<T> {
   bool get barrierDismissable => true;
   Color get barrierColor => Colors.black54;
 
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
     return child;
   }
 
-  Widget buildTransitions(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation, Widget child) {
+  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
     return new FadeTransition(
       opacity: new CurvedAnimation(
         parent: animation,

packages/flutter/lib/src/material/drawer.dart

@@ -92,18 +92,18 @@ class DrawerControllerState extends State<DrawerController> {
     }
   }
 
-  void _animationStatusChanged(PerformanceStatus status) {
+  void _animationStatusChanged(AnimationStatus status) {
     switch (status) {
-      case PerformanceStatus.forward:
+      case AnimationStatus.forward:
         _ensureHistoryEntry();
         break;
-      case PerformanceStatus.reverse:
+      case AnimationStatus.reverse:
         _historyEntry?.remove();
         _historyEntry = null;
         break;
-      case PerformanceStatus.dismissed:
+      case AnimationStatus.dismissed:
         break;
-      case PerformanceStatus.completed:
+      case AnimationStatus.completed:
         break;
     }
   }
@@ -155,7 +155,7 @@ class DrawerControllerState extends State<DrawerController> {
   final GlobalKey _gestureDetectorKey = new GlobalKey();
 
   Widget build(BuildContext context) {
-    if (_controller.status == PerformanceStatus.dismissed) {
+    if (_controller.status == AnimationStatus.dismissed) {
       return new Align(
         alignment: const FractionalOffset(0.0, 0.5),
         child: new GestureDetector(

packages/flutter/lib/src/material/dropdown.dart

@@ -193,7 +193,7 @@ class _DropDownRoute<T> extends PopupRoute<_DropDownRouteResult<T>> {
     );
   }
 
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
     return new _DropDownMenu(route: this);
   }
 }

packages/flutter/lib/src/material/floating_action_button.dart

@@ -40,7 +40,7 @@ class FloatingActionButton extends StatefulComponent {
 }
 
 class _FloatingActionButtonState extends State<FloatingActionButton> {
-  Animated<double> _childSegue;
+  Animation<double> _childSegue;
   AnimationController _childSegueController;
 
   void initState() {

packages/flutter/lib/src/material/material.dart

@@ -367,10 +367,10 @@ class _InkSplash extends InkFeature implements InkSplash {
   final bool clipToReferenceBox;
   final bool repositionToReferenceBox;
 
-  Animated<double> _radius;
+  Animation<double> _radius;
   AnimationController _radiusController;
 
-  Animated<int> _alpha;
+  Animation<int> _alpha;
   AnimationController _alphaController;
 
   void confirm() {
@@ -385,8 +385,8 @@ class _InkSplash extends InkFeature implements InkSplash {
     _alphaController.forward();
   }
 
-  void _handleAlphaStatusChanged(PerformanceStatus status) {
-    if (status == PerformanceStatus.completed)
+  void _handleAlphaStatusChanged(AnimationStatus status) {
+    if (status == AnimationStatus.completed)
       dispose();
   }
 
@@ -456,7 +456,7 @@ class _InkHighlight extends InkFeature implements InkHighlight {
   bool get active => _active;
   bool _active = true;
 
-  Animated<int> _alpha;
+  Animation<int> _alpha;
   AnimationController _alphaController;
 
   void activate() {
@@ -469,8 +469,8 @@ class _InkHighlight extends InkFeature implements InkHighlight {
     _alphaController.reverse();
   }
 
-  void _handleAlphaStatusChanged(PerformanceStatus status) {
-    if (status == PerformanceStatus.dismissed && !_active)
+  void _handleAlphaStatusChanged(AnimationStatus status) {
+    if (status == AnimationStatus.dismissed && !_active)
       dispose();
   }
 

packages/flutter/lib/src/material/page.dart

@@ -10,7 +10,7 @@ import 'package:flutter/widgets.dart';
 class _MaterialPageTransition extends AnimatedComponent {
   _MaterialPageTransition({
     Key key,
-    Animated<double> animation,
+    Animation<double> animation,
     this.child
   }) : super(
     key: key,
@@ -57,7 +57,7 @@ class MaterialPageRoute<T> extends PageRoute<T> {
   Color get barrierColor => null;
   bool canTransitionFrom(TransitionRoute nextRoute) => false;
 
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
     Widget result = builder(context);
     assert(() {
       if (result == null)
@@ -68,7 +68,7 @@ class MaterialPageRoute<T> extends PageRoute<T> {
     return result;
   }
 
-  Widget buildTransitions(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation, Widget child) {
+  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
     return new _MaterialPageTransition(
       animation: animation,
       child: child

packages/flutter/lib/src/material/popup_menu.dart

@@ -132,7 +132,7 @@ class _PopupMenuRoute<T> extends PopupRoute<T> {
     return position;
   }
 
-  Animated<double> createAnimation() {
+  Animation<double> createAnimation() {
     return new CurvedAnimation(
       parent: super.createAnimation(),
       reverseCurve: new Interval(0.0, _kMenuCloseIntervalEnd)
@@ -143,7 +143,7 @@ class _PopupMenuRoute<T> extends PopupRoute<T> {
   bool get barrierDismissable => true;
   Color get barrierColor => null;
 
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
     return new _PopupMenu(route: this);
   }
 }

packages/flutter/lib/src/material/progress_indicator.dart

@@ -38,15 +38,15 @@ abstract class ProgressIndicator extends StatefulComponent {
 }
 
 class _ProgressIndicatorState extends State<ProgressIndicator> {
-  Animated<double> _animation;
+  Animation<double> _animation;
   AnimationController _controller;
 
   void initState() {
     super.initState();
     _controller = new AnimationController(
       duration: const Duration(milliseconds: 1500)
-    )..addStatusListener((PerformanceStatus status) {
-      if (status == PerformanceStatus.completed)
+    )..addStatusListener((AnimationStatus status) {
+      if (status == AnimationStatus.completed)
         _restartAnimation();
     })..forward();
     _animation = new CurvedAnimation(parent: _controller, curve: Curves.ease);

packages/flutter/lib/src/material/scaffold.dart

@@ -227,9 +227,9 @@ class ScaffoldState extends State<Scaffold> {
     return controller;
   }
 
-  void _handleSnackBarStatusChange(PerformanceStatus status) {
+  void _handleSnackBarStatusChange(AnimationStatus status) {
     switch (status) {
-      case PerformanceStatus.dismissed:
+      case AnimationStatus.dismissed:
         assert(_snackBars.isNotEmpty);
         setState(() {
           _snackBars.removeFirst();
@@ -237,21 +237,21 @@ class ScaffoldState extends State<Scaffold> {
         if (_snackBars.isNotEmpty)
           _snackBarController.forward();
         break;
-      case PerformanceStatus.completed:
+      case AnimationStatus.completed:
         setState(() {
           assert(_snackBarTimer == null);
           // build will create a new timer if necessary to dismiss the snack bar
         });
         break;
-      case PerformanceStatus.forward:
-      case PerformanceStatus.reverse:
+      case AnimationStatus.forward:
+      case AnimationStatus.reverse:
         break;
     }
   }
 
   void _hideSnackBar() {
-    assert(_snackBarController.status == PerformanceStatus.forward ||
-           _snackBarController.status == PerformanceStatus.completed);
+    assert(_snackBarController.status == AnimationStatus.forward ||
+           _snackBarController.status == AnimationStatus.completed);
     _snackBars.first._completer.complete();
     _snackBarController.reverse();
     _snackBarTimer = null;
@@ -449,7 +449,7 @@ class _PersistentBottomSheetState extends State<_PersistentBottomSheet> {
 
   void initState() {
     super.initState();
-    assert(config.animationController.status == PerformanceStatus.forward);
+    assert(config.animationController.status == AnimationStatus.forward);
     config.animationController.addStatusListener(_handleStatusChange);
   }
 
@@ -467,8 +467,8 @@ class _PersistentBottomSheetState extends State<_PersistentBottomSheet> {
     config.animationController.reverse();
   }
 
-  void _handleStatusChange(PerformanceStatus status) {
-    if (status == PerformanceStatus.dismissed && config.onDismissed != null)
+  void _handleStatusChange(AnimationStatus status) {
+    if (status == AnimationStatus.dismissed && config.onDismissed != null)
       config.onDismissed();
   }
 

packages/flutter/lib/src/material/slider.dart

@@ -123,7 +123,7 @@ class _RenderSlider extends RenderConstrainedBox {
 
   double get _trackLength => size.width - 2.0 * _kReactionRadius;
 
-  Animated<double> _reaction;
+  Animation<double> _reaction;
   AnimationController _reactionController;
 
   HorizontalDragGestureRecognizer _drag;
@@ -186,7 +186,7 @@ class _RenderSlider extends RenderConstrainedBox {
       canvas.drawRect(new Rect.fromLTRB(trackLeft, trackTop, trackActive, trackBottom), primaryPaint);
 
     Point activeLocation = new Point(trackActive, trackCenter);
-    if (_reaction.status != PerformanceStatus.dismissed) {
+    if (_reaction.status != AnimationStatus.dismissed) {
       Paint reactionPaint = new Paint()..color = _activeColor.withAlpha(kRadialReactionAlpha);
       canvas.drawCircle(activeLocation, _reaction.value, reactionPaint);
     }

packages/flutter/lib/src/material/snack_bar.dart

@@ -65,7 +65,7 @@ class SnackBar extends StatelessComponent {
   final Widget content;
   final List<SnackBarAction> actions;
   final Duration duration;
-  final Animated<double> animation;
+  final Animation<double> animation;
 
   Widget build(BuildContext context) {
     assert(animation != null);
@@ -130,7 +130,7 @@ class SnackBar extends StatelessComponent {
     );
   }
 
-  SnackBar withAnimation(Animated<double> newAnimation, { Key fallbackKey }) {
+  SnackBar withAnimation(Animation<double> newAnimation, { Key fallbackKey }) {
     return new SnackBar(
       key: key ?? fallbackKey,
       content: content,

packages/flutter/lib/src/material/tabs.dart

@@ -382,7 +382,7 @@ class _TabsScrollBehavior extends BoundedBehavior {
 }
 
 abstract class TabBarSelectionPerformanceListener {
-  void handleStatusChange(PerformanceStatus status);
+  void handleStatusChange(AnimationStatus status);
   void handleProgressChange();
   void handleSelectionDeactivate();
 }
@@ -415,7 +415,7 @@ class TabBarSelection<T> extends StatefulComponent {
 
 class TabBarSelectionState<T> extends State<TabBarSelection<T>> {
 
-  Animated<double> get animation => _controller.view;
+  Animation<double> get animation => _controller.view;
   // Both the TabBar and TabBarView classes access _controller because they
   // alternately drive selection progress between tabs.
   final AnimationController _controller = new AnimationController(duration: _kTabBarScroll, value: 1.0);
@@ -481,7 +481,7 @@ class TabBarSelectionState<T> extends State<TabBarSelection<T>> {
     // the previous and current selection index.
 
     double value;
-    if (_controller.status == PerformanceStatus.completed)
+    if (_controller.status == AnimationStatus.completed)
       value = 0.0;
     else if (_previousValue == values.first)
       value = _controller.value;
@@ -584,11 +584,11 @@ class _TabBarState<T> extends ScrollableState<TabBar<T>> implements TabBarSelect
     _selection = null;
   }
 
-  void handleStatusChange(PerformanceStatus status) {
+  void handleStatusChange(AnimationStatus status) {
     if (config.labels.length == 0)
       return;
 
-    if (_valueIsChanging && status == PerformanceStatus.completed) {
+    if (_valueIsChanging && status == AnimationStatus.completed) {
       _valueIsChanging = false;
       _indicatorTween
         ..begin = _tabIndicatorRect(math.max(0, _selection.index - 1))
@@ -868,7 +868,7 @@ class _TabBarViewState extends PageableListState<TabBarView> implements TabBarSe
     _updateScrollBehaviorForSelectedIndex(selectedIndex);
   }
 
-  void handleStatusChange(PerformanceStatus status) {
+  void handleStatusChange(AnimationStatus status) {
   }
 
   void handleProgressChange() {
@@ -876,14 +876,14 @@ class _TabBarViewState extends PageableListState<TabBarView> implements TabBarSe
       return;
     // The TabBar is driving the TabBarSelection performance.
 
-    final Animated<double> animation = _selection.animation;
+    final Animation<double> animation = _selection.animation;
 
-    if (animation.status == PerformanceStatus.completed) {
+    if (animation.status == AnimationStatus.completed) {
       _updateItemsAndScrollBehavior();
       return;
     }
 
-    if (animation.status != PerformanceStatus.forward)
+    if (animation.status != AnimationStatus.forward)
       return;
 
     final int selectedIndex = _selection.index;

packages/flutter/lib/src/material/time_picker.dart

@@ -350,7 +350,7 @@ class _DialState extends State<_Dial> {
   }
 
   Tween<double> _thetaTween;
-  Animated<double> _theta;
+  Animation<double> _theta;
   AnimationController _thetaController;
   bool _dragging = false;
 

packages/flutter/lib/src/material/toggleable.dart

@@ -99,15 +99,15 @@ abstract class RenderToggleable extends RenderConstrainedBox {
 
   AnimationController get reactionController => _reactionController;
   AnimationController _reactionController;
-  Animated<double> _reaction;
+  Animation<double> _reaction;
 
   TapGestureRecognizer _tap;
 
-  void _handlePositionStateChanged(PerformanceStatus status) {
+  void _handlePositionStateChanged(AnimationStatus status) {
     if (isInteractive) {
-      if (status == PerformanceStatus.completed && !_value)
+      if (status == AnimationStatus.completed && !_value)
         onChanged(true);
-      else if (status == PerformanceStatus.dismissed && _value)
+      else if (status == AnimationStatus.dismissed && _value)
         onChanged(false);
     }
   }

packages/flutter/lib/src/material/tooltip.dart

@@ -78,14 +78,14 @@ class _TooltipState extends State<Tooltip> {
   void initState() {
     super.initState();
     _controller = new AnimationController(duration: config.fadeDuration)
-      ..addStatusListener((PerformanceStatus status) {
+      ..addStatusListener((AnimationStatus status) {
         switch (status) {
-          case PerformanceStatus.completed:
+          case AnimationStatus.completed:
             assert(_entry != null);
             assert(_timer == null);
             resetShowTimer();
             break;
-          case PerformanceStatus.dismissed:
+          case AnimationStatus.dismissed:
             assert(_entry != null);
             assert(_timer == null);
             _entry.remove();
@@ -117,7 +117,7 @@ class _TooltipState extends State<Tooltip> {
   }
 
   void resetShowTimer() {
-    assert(_controller.status == PerformanceStatus.completed);
+    assert(_controller.status == AnimationStatus.completed);
     assert(_entry != null);
     _timer = new Timer(config.showDuration, hideTooltip);
   }
@@ -149,7 +149,7 @@ class _TooltipState extends State<Tooltip> {
       Overlay.of(context).insert(_entry);
     }
     _timer?.cancel();
-    if (_controller.status != PerformanceStatus.completed) {
+    if (_controller.status != AnimationStatus.completed) {
       _timer = null;
       _controller.forward();
     } else {
@@ -249,7 +249,7 @@ class _TooltipOverlay extends StatelessComponent {
   final double borderRadius;
   final double height;
   final EdgeDims padding;
-  final Animated<double> animation;
+  final Animation<double> animation;
   final Point target;
   final double verticalOffset;
   final EdgeDims screenEdgeMargin;

packages/flutter/lib/src/widgets/dismissable.dart

@@ -73,8 +73,8 @@ class _DismissableState extends State<Dismissable> {
   void initState() {
     super.initState();
     _dismissController = new AnimationController(duration: _kCardDismissDuration);
-    _dismissController.addStatusListener((PerformanceStatus status) {
-      if (status == PerformanceStatus.completed)
+    _dismissController.addStatusListener((AnimationStatus status) {
+      if (status == AnimationStatus.completed)
         _handleDismissCompleted();
     });
   }
@@ -251,9 +251,9 @@ class _DismissableState extends State<Dismissable> {
   Widget build(BuildContext context) {
     if (_resizeController != null) {
       // make sure you remove this widget once it's been dismissed!
-      assert(_resizeController.status == PerformanceStatus.forward);
+      assert(_resizeController.status == AnimationStatus.forward);
 
-      Animated<double> squashAxisExtent = new Tween<double>(
+      Animation<double> squashAxisExtent = new Tween<double>(
         begin: _directionIsYAxis ? _size.width : _size.height,
         end: 0.0
       ).animate(new CurvedAnimation(

packages/flutter/lib/src/widgets/enter_exit_transition.dart

@@ -32,7 +32,7 @@ class SmoothlyResizingOverflowBox extends StatefulComponent {
 class _SmoothlyResizingOverflowBoxState extends State<SmoothlyResizingOverflowBox> {
   SizeTween _sizeTween;
   CurveTween _curveTween;
-  Animated<Size> _size;
+  Animation<Size> _size;
   AnimationController _sizeController;
 
   void initState() {
@@ -100,9 +100,9 @@ class _Entry {
   }
 }
 
-typedef Widget TransitionBuilderCallback(Animated<double> animation, Widget child);
+typedef Widget TransitionBuilderCallback(Animation<double> animation, Widget child);
 
-Widget _identityTransition(Animated<double> animation, Widget child) => child;
+Widget _identityTransition(Animation<double> animation, Widget child) => child;
 
 class EnterExitTransition extends StatefulComponent {
   EnterExitTransition({

packages/flutter/lib/src/widgets/heroes.dart

@@ -73,7 +73,7 @@ class _HeroManifest {
 
 abstract class HeroHandle {
   bool get alwaysAnimate;
-  _HeroManifest _takeChild(Rect animationArea, Animated<double> currentAnimation);
+  _HeroManifest _takeChild(Rect animationArea, Animation<double> currentAnimation);
 }
 
 class Hero extends StatefulComponent {
@@ -167,7 +167,7 @@ class HeroState extends State<Hero> implements HeroHandle {
 
   bool get alwaysAnimate => config.alwaysAnimate;
 
-  _HeroManifest _takeChild(Rect animationArea, Animated<double> currentAnimation) {
+  _HeroManifest _takeChild(Rect animationArea, Animation<double> currentAnimation) {
     assert(_mode == _HeroMode.measured || _mode == _HeroMode.taken);
     final RenderBox renderObject = context.findRenderObject();
     final Point heroTopLeft = renderObject.localToGlobal(Point.origin);
@@ -263,7 +263,7 @@ class _HeroQuestState implements HeroHandle {
 
   bool get taken => _taken;
   bool _taken = false;
-  _HeroManifest _takeChild(Rect animationArea, Animated<double> currentAnimation) {
+  _HeroManifest _takeChild(Rect animationArea, Animation<double> currentAnimation) {
     assert(!taken);
     _taken = true;
     Set<HeroState> states = sourceStates;
@@ -278,7 +278,7 @@ class _HeroQuestState implements HeroHandle {
     );
   }
 
-  Widget build(BuildContext context, Animated<double> animation) {
+  Widget build(BuildContext context, Animation<double> animation) {
     return new PositionedTransition(
       rect: currentRect.animate(animation),
       child: new RotationTransition(
@@ -376,14 +376,14 @@ class HeroParty {
     _heroes = _newHeroes;
   }
 
-  Animated<double> _currentAnimation;
+  Animation<double> _currentAnimation;
 
   void _clearCurrentAnimation() {
     _currentAnimation?.removeStatusListener(_handleUpdate);
     _currentAnimation = null;
   }
 
-  void setAnimation(Animated<double> animation) {
+  void setAnimation(Animation<double> animation) {
     assert(animation != null || _heroes.length == 0);
     if (animation != _currentAnimation) {
       _clearCurrentAnimation();
@@ -392,9 +392,9 @@ class HeroParty {
     }
   }
 
-  void _handleUpdate(PerformanceStatus status) {
-    if (status == PerformanceStatus.completed ||
-        status == PerformanceStatus.dismissed) {
+  void _handleUpdate(AnimationStatus status) {
+    if (status == AnimationStatus.completed ||
+        status == AnimationStatus.dismissed) {
       for (_HeroQuestState hero in _heroes) {
         if (hero.targetState != null)
           hero.targetState._setChild(hero.key);
@@ -417,7 +417,7 @@ class HeroController extends NavigatorObserver {
   }
 
   HeroParty _party;
-  Animated<double> _animation;
+  Animation<double> _animation;
   PageRoute _from;
   PageRoute _to;
 
@@ -452,7 +452,7 @@ class HeroController extends NavigatorObserver {
 
   void _checkForHeroQuest() {
     if (_from != null && _to != null && _from != _to) {
-      _to.offstage = _to.animation.status != PerformanceStatus.completed;
+      _to.offstage = _to.animation.status != AnimationStatus.completed;
       Scheduler.instance.addPostFrameCallback(_updateQuest);
     }
   }
@@ -505,9 +505,9 @@ class HeroController extends NavigatorObserver {
     Map<Object, HeroHandle> heroesTo = Hero.of(_to.subtreeContext, mostValuableKeys);
     _to.offstage = false;
 
-    Animated<double> animation = _animation;
+    Animation<double> animation = _animation;
     Curve curve = Curves.ease;
-    if (animation.status == PerformanceStatus.reverse) {
+    if (animation.status == AnimationStatus.reverse) {
       animation = new ReverseAnimation(animation);
       curve = new Interval(animation.value, 1.0, curve: curve);
     }

packages/flutter/lib/src/widgets/implicit_animations.dart

@@ -84,8 +84,8 @@ typedef Tween<T> TweenVisitor<T>(Tween<T> tween, T targetValue, TweenConstructor
 abstract class AnimatedWidgetBaseState<T extends AnimatedWidgetBase> extends State<T> {
   AnimationController _controller;
 
-  Animated<double> get animation => _animation;
-  Animated<double> _animation;
+  Animation<double> get animation => _animation;
+  Animation<double> _animation;
 
   void initState() {
     super.initState();

packages/flutter/lib/src/widgets/modal_barrier.dart

@@ -46,12 +46,12 @@ class ModalBarrier extends StatelessComponent {
 class AnimatedModalBarrier extends AnimatedComponent {
   AnimatedModalBarrier({
     Key key,
-    Animated<Color> color,
+    Animation<Color> color,
     this.dismissable: true
   }) : color = color, super(key: key, animation: color);
 
   /// If non-null, fill the barrier with this color.
-  final Animated<Color> color;
+  final Animation<Color> color;
 
   /// Whether touching the barrier will pop the current route off the [Navigator].
   final bool dismissable;

packages/flutter/lib/src/widgets/routes.dart

@@ -92,8 +92,8 @@ abstract class TransitionRoute<T> extends OverlayRoute<T> {
   Duration get transitionDuration;
   bool get opaque;
 
-  Animated<double> get animation => _animation;
-  Animated<double> _animation;
+  Animation<double> get animation => _animation;
+  Animation<double> _animation;
   AnimationController _controller;
 
   /// Called to create the animation controller that will drive the transitions to
@@ -108,25 +108,25 @@ abstract class TransitionRoute<T> extends OverlayRoute<T> {
   /// Called to create the animation that exposes the current progress of
   /// the transition controlled by the animation controller created by
   /// [createAnimationController()].
-  Animated<double> createAnimation() {
+  Animation<double> createAnimation() {
     assert(_controller != null);
     return _controller.view;
   }
 
   T _result;
 
-  void handleStatusChanged(PerformanceStatus status) {
+  void handleStatusChanged(AnimationStatus status) {
     switch (status) {
-      case PerformanceStatus.completed:
+      case AnimationStatus.completed:
         if (overlayEntries.isNotEmpty)
           overlayEntries.first.opaque = opaque;
         break;
-      case PerformanceStatus.forward:
-      case PerformanceStatus.reverse:
+      case AnimationStatus.forward:
+      case AnimationStatus.reverse:
         if (overlayEntries.isNotEmpty)
           overlayEntries.first.opaque = false;
         break;
-      case PerformanceStatus.dismissed:
+      case AnimationStatus.dismissed:
         assert(!overlayEntries.first.opaque);
         finished(); // clear the overlays
         assert(overlayEntries.isEmpty);
@@ -134,7 +134,7 @@ abstract class TransitionRoute<T> extends OverlayRoute<T> {
     }
   }
 
-  Animated<double> get forwardAnimation => _forwardAnimation;
+  Animation<double> get forwardAnimation => _forwardAnimation;
   final ProxyAnimation _forwardAnimation = new ProxyAnimation(kAlwaysDismissedAnimation);
 
   void install(OverlayEntry insertionPoint) {
@@ -177,7 +177,7 @@ abstract class TransitionRoute<T> extends OverlayRoute<T> {
 
   void _updateForwardAnimation(Route nextRoute) {
     if (nextRoute is TransitionRoute && canTransitionTo(nextRoute) && nextRoute.canTransitionFrom(this)) {
-      Animated<double> current = _forwardAnimation.masterAnimation;
+      Animation<double> current = _forwardAnimation.masterAnimation;
       if (current != null) {
         if (current is TrainHoppingAnimation) {
           TrainHoppingAnimation newAnimation;
@@ -320,7 +320,7 @@ class _ModalScopeState extends State<_ModalScope> {
     super.dispose();
   }
 
-  void _animationStatusChanged(PerformanceStatus status) {
+  void _animationStatusChanged(AnimationStatus status) {
     setState(() {
       // The animation's states are our build state, and they changed already.
     });
@@ -342,7 +342,7 @@ class _ModalScopeState extends State<_ModalScope> {
       contents = new Focus(
         key: new GlobalObjectKey(config.route),
         child: new IgnorePointer(
-          ignoring: config.route.animation?.status == PerformanceStatus.reverse,
+          ignoring: config.route.animation?.status == AnimationStatus.reverse,
           child: config.route.buildTransitions(
             context,
             config.route.animation,
@@ -396,8 +396,8 @@ abstract class ModalRoute<T> extends TransitionRoute<T> with LocalHistoryRoute<T
   // The API for subclasses to override - used by _ModalScope
 
   ModalPosition getPosition(BuildContext context) => null;
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation);
-  Widget buildTransitions(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation, Widget child) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation);
+  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation, Widget child) {
     return child;
   }
 
@@ -442,7 +442,7 @@ abstract class ModalRoute<T> extends TransitionRoute<T> with LocalHistoryRoute<T
     Widget barrier;
     if (barrierColor != null) {
       assert(barrierColor != _kTransparent);
-      Animated<Color> color = new ColorTween(
+      Animation<Color> color = new ColorTween(
         begin: _kTransparent,
         end: barrierColor
       ).animate(new CurvedAnimation(
@@ -456,9 +456,9 @@ abstract class ModalRoute<T> extends TransitionRoute<T> with LocalHistoryRoute<T
     } else {
       barrier = new ModalBarrier(dismissable: barrierDismissable);
     }
-    assert(animation.status != PerformanceStatus.dismissed);
+    assert(animation.status != AnimationStatus.dismissed);
     return new IgnorePointer(
-      ignoring: animation.status == PerformanceStatus.reverse,
+      ignoring: animation.status == AnimationStatus.reverse,
       child: barrier
     );
   }

packages/flutter/lib/src/widgets/status_transitions.dart

@@ -14,7 +14,7 @@ abstract class StatusTransitionComponent extends StatefulComponent {
     assert(animation != null);
   }
 
-  final Animated<double> animation;
+  final Animation<double> animation;
 
   Widget build(BuildContext context);
 
@@ -39,7 +39,7 @@ class _StatusTransitionState extends State<StatusTransitionComponent> {
     super.dispose();
   }
 
-  void _animationStatusChanged(PerformanceStatus status) {
+  void _animationStatusChanged(AnimationStatus status) {
     setState(() {
       // The animation's state is our build state, and it changed already.
     });

packages/flutter/lib/src/widgets/transitions.dart

@@ -14,55 +14,6 @@ import 'framework.dart';
 export 'package:flutter/animation.dart' show AnimationDirection;
 export 'package:flutter/rendering.dart' show RelativeRect;
 
-abstract class TransitionComponent extends StatefulComponent {
-  TransitionComponent({
-    Key key,
-    this.performance
-  }) : super(key: key) {
-    assert(performance != null);
-  }
-
-  final PerformanceView performance;
-
-  Widget build(BuildContext context);
-
-  _TransitionState createState() => new _TransitionState();
-
-  void debugFillDescription(List<String> description) {
-    super.debugFillDescription(description);
-    description.add('performance: $performance');
-  }
-}
-
-class _TransitionState extends State<TransitionComponent> {
-  void initState() {
-    super.initState();
-    config.performance.addListener(_performanceChanged);
-  }
-
-  void didUpdateConfig(TransitionComponent oldConfig) {
-    if (config.performance != oldConfig.performance) {
-      oldConfig.performance.removeListener(_performanceChanged);
-      config.performance.addListener(_performanceChanged);
-    }
-  }
-
-  void dispose() {
-    config.performance.removeListener(_performanceChanged);
-    super.dispose();
-  }
-
-  void _performanceChanged() {
-    setState(() {
-      // The performance's state is our build state, and it changed already.
-    });
-  }
-
-  Widget build(BuildContext context) {
-    return config.build(context);
-  }
-}
-
 abstract class AnimatedComponent extends StatefulComponent {
   AnimatedComponent({
     Key key,
@@ -71,7 +22,7 @@ abstract class AnimatedComponent extends StatefulComponent {
     assert(animation != null);
   }
 
-  final Animated<Object> animation;
+  final Animation<Object> animation;
 
   Widget build(BuildContext context);
 
@@ -112,30 +63,15 @@ class _AnimatedComponentState extends State<AnimatedComponent> {
   }
 }
 
-abstract class TransitionWithChild extends TransitionComponent {
-  TransitionWithChild({
-    Key key,
-    this.child,
-    PerformanceView performance
-  }) : super(key: key, performance: performance);
-
-  final Widget child;
-
-  Widget build(BuildContext context) => buildWithChild(context, child);
-
-  Widget buildWithChild(BuildContext context, Widget child);
-}
-
 class SlideTransition extends AnimatedComponent {
   SlideTransition({
     Key key,
-    Animated<FractionalOffset> position,
-    PerformanceView performance,
+    Animation<FractionalOffset> position,
     this.transformHitTests: true,
     this.child
   }) : position = position, super(key: key, animation: position);
 
-  final Animated<FractionalOffset> position;
+  final Animation<FractionalOffset> position;
   final bool transformHitTests;
   final Widget child;
 
@@ -151,12 +87,12 @@ class SlideTransition extends AnimatedComponent {
 class ScaleTransition extends AnimatedComponent {
   ScaleTransition({
     Key key,
-    Animated<double> scale,
+    Animation<double> scale,
     this.alignment: const FractionalOffset(0.5, 0.5),
     this.child
   }) : scale = scale, super(key: key, animation: scale);
 
-  final Animated<double> scale;
+  final Animation<double> scale;
   final FractionalOffset alignment;
   final Widget child;
 
@@ -175,11 +111,11 @@ class ScaleTransition extends AnimatedComponent {
 class RotationTransition extends AnimatedComponent {
   RotationTransition({
     Key key,
-    Animated<double> turns,
+    Animation<double> turns,
     this.child
   }) : turns = turns, super(key: key, animation: turns);
 
-  final Animated<double> turns;
+  final Animation<double> turns;
   final Widget child;
 
   Widget build(BuildContext context) {
@@ -196,11 +132,11 @@ class RotationTransition extends AnimatedComponent {
 class FadeTransition extends AnimatedComponent {
   FadeTransition({
     Key key,
-    Animated<double> opacity,
+    Animation<double> opacity,
     this.child
   }) : opacity = opacity, super(key: key, animation: opacity);
 
-  final Animated<double> opacity;
+  final Animation<double> opacity;
   final Widget child;
 
   Widget build(BuildContext context) {
@@ -211,11 +147,11 @@ class FadeTransition extends AnimatedComponent {
 class ColorTransition extends AnimatedComponent {
   ColorTransition({
     Key key,
-    Animated<Color> color,
+    Animation<Color> color,
     this.child
   }) : color = color, super(key: key, animation: color);
 
-  final Animated<Color> color;
+  final Animation<Color> color;
   final Widget child;
 
   Widget build(BuildContext context) {
@@ -226,61 +162,6 @@ class ColorTransition extends AnimatedComponent {
   }
 }
 
-class SquashTransition extends TransitionWithChild {
-  SquashTransition({
-    Key key,
-    this.width,
-    this.height,
-    PerformanceView performance,
-    Widget child
-  }) : super(key: key,
-             performance: performance,
-             child: child);
-
-  final AnimatedValue<double> width;
-  final AnimatedValue<double> height;
-
-  Widget buildWithChild(BuildContext context, Widget child) {
-    if (width != null)
-      performance.updateVariable(width);
-    if (height != null)
-      performance.updateVariable(height);
-    return new SizedBox(width: width?.value, height: height?.value, child: child);
-  }
-}
-
-class AlignTransition extends TransitionWithChild {
-  AlignTransition({
-    Key key,
-    this.alignment,
-    this.widthFactor,
-    this.heightFactor,
-    PerformanceView performance,
-    Widget child
-  }) : super(key: key,
-             performance: performance,
-             child: child);
-
-  final AnimatedValue<FractionalOffset> alignment;
-  final AnimatedValue<double> widthFactor;
-  final AnimatedValue<double> heightFactor;
-
-  Widget buildWithChild(BuildContext context, Widget child) {
-    if (alignment != null)
-      performance.updateVariable(alignment);
-    if (widthFactor != null)
-      performance.updateVariable(widthFactor);
-    if (heightFactor != null)
-      performance.updateVariable(heightFactor);
-    return new Align(
-      alignment: alignment?.value,
-      widthFactor: widthFactor?.value,
-      heightFactor: heightFactor?.value,
-      child: child
-    );
-  }
-}
-
 /// An animated variable containing a RelativeRectangle
 ///
 /// This class specializes the interpolation of AnimatedValue<RelativeRect> to
@@ -302,13 +183,13 @@ class RelativeRectTween extends Tween<RelativeRect> {
 class PositionedTransition extends AnimatedComponent {
   PositionedTransition({
     Key key,
-    Animated<RelativeRect> rect,
+    Animation<RelativeRect> rect,
     this.child
   }) : rect = rect, super(key: key, animation: rect) {
     assert(rect != null);
   }
 
-  final Animated<RelativeRect> rect;
+  final Animation<RelativeRect> rect;
   final Widget child;
 
   Widget build(BuildContext context) {
@@ -322,31 +203,12 @@ class PositionedTransition extends AnimatedComponent {
   }
 }
 
-class BuilderTransition extends TransitionComponent {
-  BuilderTransition({
-    Key key,
-    this.variables: const <AnimatedValue>[],
-    this.builder,
-    PerformanceView performance
-  }) : super(key: key,
-             performance: performance);
-
-  final List<AnimatedValue> variables;
-  final WidgetBuilder builder;
-
-  Widget build(BuildContext context) {
-    for (int i = 0; i < variables.length; ++i)
-      performance.updateVariable(variables[i]);
-    return builder(context);
-  }
-}
-
 typedef Widget TransitionBuilder(BuildContext context, Widget child);
 
 class AnimatedBuilder extends AnimatedComponent {
   AnimatedBuilder({
     Key key,
-    Animated<Object> animation,
+    Animation<Object> animation,
     this.builder,
     this.child
   }) : super(key: key, animation: animation);

packages/flutter/test/widget/page_forward_transitions_test.dart

@@ -12,7 +12,7 @@ class TestTransition extends AnimatedComponent {
     Key key,
     this.childFirstHalf,
     this.childSecondHalf,
-    Animated<double> animation
+    Animation<double> animation
   }) : super(key: key, animation: animation) {
     assert(animation != null);
   }
@@ -21,7 +21,7 @@ class TestTransition extends AnimatedComponent {
   final Widget childSecondHalf;
 
   Widget build(BuildContext context) {
-    final Animated<double> animation = this.animation;
+    final Animation<double> animation = this.animation;
     if (animation.value >= 0.5)
       return childSecondHalf;
     return childFirstHalf;
@@ -33,7 +33,7 @@ class TestRoute<T> extends PageRoute<T> {
   final Widget child;
   Duration get transitionDuration => kMaterialPageRouteTransitionDuration;
   Color get barrierColor => null;
-  Widget buildPage(BuildContext context, Animated<double> animation, Animated<double> forwardAnimation) {
+  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation) {
     return child;
   }
 }