From 9e45b85e728feaa085dc4d4bb07f3a2966d4fcbd Mon Sep 17 00:00:00 2001
From: Adam Barth <abarth@chromium.org>
Date: Wed, 24 Feb 2016 12:15:57 -0800
Subject: [PATCH] Keep AnimationController's _value in bounds

Rather than clamping _value on read, we now clamp the value when writing it,
which simplifies reasoning about _value.
---
 .../flutter/lib/src/animation/animation_controller.dart     | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/flutter/lib/src/animation/animation_controller.dart b/packages/flutter/lib/src/animation/animation_controller.dart
index e0aee1c9783..ca9a49c0d4d 100644
--- a/packages/flutter/lib/src/animation/animation_controller.dart
+++ b/packages/flutter/lib/src/animation/animation_controller.dart
@@ -88,7 +88,7 @@ class AnimationController extends Animation<double>
   /// The current value of the animation.
   ///
   /// Setting this value stops the current animation.
-  double get value => _value.clamp(lowerBound, upperBound);
+  double get value => _value;
   double _value;
   void set value(double newValue) {
     assert(newValue != null);
@@ -174,7 +174,7 @@ class AnimationController extends Animation<double>
     assert(simulation != null);
     assert(!isAnimating);
     _simulation = simulation;
-    _value = simulation.x(0.0);
+    _value = simulation.x(0.0).clamp(lowerBound, upperBound);
     return _ticker.start();
   }
 
@@ -200,7 +200,7 @@ class AnimationController extends Animation<double>
 
   void _tick(Duration elapsed) {
     double elapsedInSeconds = elapsed.inMicroseconds.toDouble() / Duration.MICROSECONDS_PER_SECOND;
-    _value = _simulation.x(elapsedInSeconds);
+    _value = _simulation.x(elapsedInSeconds).clamp(lowerBound, upperBound);
     if (_simulation.isDone(elapsedInSeconds))
       stop();
     notifyListeners();