From de4ffbec3bafa0a2fa6a881287bac491e72a8dd4 Mon Sep 17 00:00:00 2001
From: Jumar Macato <hikari.netto23@gmail.com>
Date: Fri, 18 May 2018 18:26:04 +0800
Subject: [PATCH] Fix introduced bug in neutral keyframe values.

---
 samples/RenderTest/Pages/AnimationsPage.xaml  | 40 ++++-------------
 src/Avalonia.Animation/DoubleKeyFrames.cs     | 18 ++++++--
 src/Avalonia.Animation/KeyFramePair`1.cs      |  6 +--
 .../KeyFramesStateMachine`1.cs                | 10 +++--
 src/Avalonia.Animation/KeyFrames`1.cs         | 43 ++++++++-----------
 .../Animation/TransformKeyFrames.cs           |  2 +-
 6 files changed, 51 insertions(+), 68 deletions(-)

diff --git a/samples/RenderTest/Pages/AnimationsPage.xaml b/samples/RenderTest/Pages/AnimationsPage.xaml
index 0c54f61361..c57f0764f9 100644
--- a/samples/RenderTest/Pages/AnimationsPage.xaml
+++ b/samples/RenderTest/Pages/AnimationsPage.xaml
@@ -38,7 +38,6 @@
         <Setter Property="Margin" Value="15"/>
         <Setter Property="Width" Value="100"/>
         <Setter Property="Height" Value="100"/>
-        <Setter Property="Background" Value="Cyan"/>
         <Setter Property="Child" Value="{StaticResource Acorn}"/>
       </Style>
       <Style Selector="Border.Rect1:pointerover">
@@ -76,7 +75,7 @@
           </Animation>
         </Style.Animations>
       </Style>
-      <Style Selector="Border.Rect2a">
+      <Style Selector="Border.Rect3">
         <Setter Property="Child" Value="{StaticResource Heart}"/>
         <Style.Animations>
           <Animation Duration="0:0:0.5" Easing="QuadraticEaseInOut" RepeatBehavior="Loop">
@@ -93,7 +92,7 @@
           </Animation>
         </Style.Animations>
       </Style>
-      <Style Selector="Border.Rect3:pointerover">
+      <Style Selector="Border.Rect4:pointerover">
         <Style.Animations>
           <Animation Duration="0:0:3" Easing="BounceEaseInOut">
             <TransformKeyFrames Property="TranslateTransform.Y">
@@ -104,7 +103,7 @@
           </Animation>
         </Style.Animations>
       </Style>
-      <Style Selector="Border.Rect4:pointerover">
+      <Style Selector="Border.Rect5:pointerover">
         <Style.Animations>
           <Animation Duration="0:0:3" Easing="CircularEaseInOut">
             <TransformKeyFrames Property="SkewTransform.AngleX">
@@ -125,34 +124,11 @@
         <Button Content="{Binding PlayStateText}" Command="{Binding ToggleGlobalPlayState}"/>
       </StackPanel>
       <WrapPanel ClipToBounds="False">
-        <Border Classes="Test Rect1" Background="DarkRed">
-          <Border.RenderTransform>
-            <TransformGroup>
-              <RotateTransform/>
-              <ScaleTransform/>
-            </TransformGroup>
-          </Border.RenderTransform>
-         </Border>
-        <Border Classes="Test Rect2a" Background="Transparent">
-          <Border.RenderTransform>
-            <ScaleTransform/>
-          </Border.RenderTransform>
-        </Border>
-        <Border Classes="Test Rect2" Background="DarkMagenta">
-          <Border.RenderTransform>
-            <ScaleTransform/>
-          </Border.RenderTransform>
-        </Border>
-        <Border Classes="Test Rect3" Background="Navy">
-          <Border.RenderTransform>
-            <TranslateTransform/>
-          </Border.RenderTransform>
-        </Border>
-        <Border Classes="Test Rect4" Background="SeaGreen">
-          <Border.RenderTransform>
-            <SkewTransform/>
-          </Border.RenderTransform>
-        </Border>
+        <Border Classes="Test Rect1" Background="DarkRed"/>
+        <Border Classes="Test Rect2" Background="Magenta"/>
+        <Border Classes="Test Rect3"/>
+        <Border Classes="Test Rect4" Background="Navy"/>
+        <Border Classes="Test Rect5" Background="SeaGreen"/>
       </WrapPanel>
     </StackPanel>
   </Grid>
diff --git a/src/Avalonia.Animation/DoubleKeyFrames.cs b/src/Avalonia.Animation/DoubleKeyFrames.cs
index 96fc19ad85..1a45ca403d 100644
--- a/src/Avalonia.Animation/DoubleKeyFrames.cs
+++ b/src/Avalonia.Animation/DoubleKeyFrames.cs
@@ -16,11 +16,23 @@ namespace Avalonia.Animation
     {
 
         /// <inheritdocs/>
-        protected override double DoInterpolation(double t)
+        protected override double DoInterpolation(double t, double neutralValue)
         {
             var pair = GetKFPairAndIntraKFTime(t);
-            double y0 = pair.KFPair.FirstKeyFrame.Value;
-            double y1 = pair.KFPair.SecondKeyFrame.Value;
+            double y0, y1;
+
+            var firstKF = pair.KFPair.FirstKeyFrame;
+            var secondKF = pair.KFPair.SecondKeyFrame;
+
+            if (firstKF.Value.isNeutral)
+                y0 = neutralValue;
+            else
+                y0 = firstKF.Value.TargetValue;
+
+            if (secondKF.Value.isNeutral)
+                y1 = neutralValue;
+            else
+                y1 = secondKF.Value.TargetValue;
 
             // Do linear parametric interpolation 
             return y0 + (pair.IntraKFTime) * (y1 - y0);
diff --git a/src/Avalonia.Animation/KeyFramePair`1.cs b/src/Avalonia.Animation/KeyFramePair`1.cs
index 656950ab12..ecb5f33857 100644
--- a/src/Avalonia.Animation/KeyFramePair`1.cs
+++ b/src/Avalonia.Animation/KeyFramePair`1.cs
@@ -22,7 +22,7 @@ namespace Avalonia.Animation
         /// </summary>
         /// <param name="FirstKeyFrame"></param>
         /// <param name="LastKeyFrame"></param>
-        public KeyFramePair(KeyValuePair<double, T> FirstKeyFrame, KeyValuePair<double, T> LastKeyFrame) : this()
+        public KeyFramePair(KeyValuePair<double, (T, bool)> FirstKeyFrame, KeyValuePair<double, (T, bool)> LastKeyFrame) : this()
         {
             this.FirstKeyFrame = FirstKeyFrame;
             this.SecondKeyFrame = LastKeyFrame;
@@ -31,11 +31,11 @@ namespace Avalonia.Animation
         /// <summary>
         /// First <see cref="KeyFrame"/> object.
         /// </summary>
-        public KeyValuePair<double, T> FirstKeyFrame { get; private set; }
+        public KeyValuePair<double, (T TargetValue, bool isNeutral)> FirstKeyFrame { get; private set; }
 
         /// <summary>
         /// Second <see cref="KeyFrame"/> object.
         /// </summary>
-        public KeyValuePair<double, T> SecondKeyFrame { get; private set; }
+        public KeyValuePair<double, (T TargetValue, bool isNeutral)> SecondKeyFrame { get; private set; }
     }
 }
\ No newline at end of file
diff --git a/src/Avalonia.Animation/KeyFramesStateMachine`1.cs b/src/Avalonia.Animation/KeyFramesStateMachine`1.cs
index 1ac652cc63..d9fcff086c 100644
--- a/src/Avalonia.Animation/KeyFramesStateMachine`1.cs
+++ b/src/Avalonia.Animation/KeyFramesStateMachine`1.cs
@@ -32,6 +32,7 @@ namespace Avalonia.Animation
         private KeyFrames<T> _parent;
         private Animation _targetAnimation;
         private Animatable _targetControl;
+        private T _neutralValue;
         internal bool _unsubscribe = false;
         private IObserver<object> _targetObserver;
 
@@ -55,6 +56,7 @@ namespace Avalonia.Animation
             _parent = keyframes;
             _targetAnimation = animation;
             _targetControl = control;
+            _neutralValue = (T)_targetControl.GetValue(_parent.Property);
 
             _delayTotalFrameCount = (ulong)(animation.Delay.Ticks / Timing.FrameTick.Ticks);
             _durationTotalFrameCount = (ulong)(animation.Duration.Ticks / Timing.FrameTick.Ticks);
@@ -95,7 +97,7 @@ namespace Avalonia.Animation
                 _currentState = KeyFramesStates.DoRun;
         }
 
-        public void Step(PlayState _playState, Func<double, T> Interpolator)
+        public void Step(PlayState _playState, Func<double, T, T> Interpolator)
         {
             try
             {
@@ -107,7 +109,7 @@ namespace Avalonia.Animation
             }
         }
 
-        private void InternalStep(PlayState _playState, Func<double, T> Interpolator)
+        private void InternalStep(PlayState _playState, Func<double, T, T> Interpolator)
         {
             if (!_gotFirstKFValue)
             {
@@ -200,7 +202,7 @@ namespace Avalonia.Animation
                     _easedTime = _targetAnimation.Easing.Ease(_tempDuration);
 
                     _durationFrameCount++;
-                    _lastInterpValue = Interpolator(_easedTime);
+                    _lastInterpValue = Interpolator(_easedTime, _neutralValue);
                     _targetObserver.OnNext(_lastInterpValue);
                     _currentState = KeyFramesStates.DoRun;
 
@@ -262,6 +264,6 @@ namespace Avalonia.Animation
         {
             _unsubscribe = true;
             _currentState = KeyFramesStates.Disposed;
-        } 
+        }
     }
 }
\ No newline at end of file
diff --git a/src/Avalonia.Animation/KeyFrames`1.cs b/src/Avalonia.Animation/KeyFrames`1.cs
index 7399d33f06..e67462403d 100644
--- a/src/Avalonia.Animation/KeyFrames`1.cs
+++ b/src/Avalonia.Animation/KeyFrames`1.cs
@@ -19,11 +19,9 @@ namespace Avalonia.Animation
         /// <summary>
         /// List of type-converted keyframes.
         /// </summary>
-        private Dictionary<double, T> _convertedKeyframes = new Dictionary<double, T>();
+        private Dictionary<double, (T, bool isNeutral)> _convertedKeyframes = new Dictionary<double, (T, bool)>();
 
         private bool _isVerfifiedAndConverted;
-        private Animation _animation;
-        private Animatable _target;
 
         /// <summary>
         /// Gets or sets the target property for the keyframe.
@@ -34,11 +32,7 @@ namespace Avalonia.Animation
         public virtual IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch)
         {
             if (!_isVerfifiedAndConverted)
-            {
-                this._animation = animation;
-                this._target = control;
-                VerifyConvertKeyFrames(typeof(T));
-            }
+                VerifyConvertKeyFrames(animation, typeof(T));
 
             return obsMatch
                 .Where(p => p == true)
@@ -46,7 +40,7 @@ namespace Avalonia.Animation
                 .Where(p => Timing.GetGlobalPlayState() != PlayState.Pause)
                 .Subscribe(_ =>
                 {
-                    var timerObs = RunKeyFrames();
+                    var timerObs = RunKeyFrames(animation, control);
                 });
         }
 
@@ -60,9 +54,8 @@ namespace Avalonia.Animation
         /// <param name="t">The time parameter, relative to the total animation time</param>
         protected (double IntraKFTime, KeyFramePair<T> KFPair) GetKFPairAndIntraKFTime(double t)
         {
-            KeyValuePair<double, T> firstCue, lastCue;
+            KeyValuePair<double, (T, bool)> firstCue, lastCue;
             int kvCount = _convertedKeyframes.Count();
-
             if (kvCount > 2)
             {
                 if (DoubleUtils.AboutEqual(t, 0.0) || t < 0.0)
@@ -97,10 +90,10 @@ namespace Avalonia.Animation
         /// <summary>
         /// Runs the KeyFrames Animation.
         /// </summary>
-        private IDisposable RunKeyFrames()
+        private IDisposable RunKeyFrames(Animation animation, Animatable control)
         {
             var _kfStateMach = new KeyFramesStateMachine<T>();
-            _kfStateMach.Initialize(_animation, _target, this);
+            _kfStateMach.Initialize(animation, control, this);
 
             Timing.AnimationStateTimer
                         .TakeWhile(_ => !_kfStateMach._unsubscribe)
@@ -109,18 +102,18 @@ namespace Avalonia.Animation
                             _kfStateMach.Step(p, DoInterpolation);
                         });
 
-            return _target.Bind(Property, _kfStateMach, BindingPriority.Animation);
+            return control.Bind(Property, _kfStateMach, BindingPriority.Animation);
         }
 
         /// <summary>
         /// Interpolates a value given the desired time.
         /// </summary>
-        protected abstract T DoInterpolation(double time);
+        protected abstract T DoInterpolation(double time, T neutralValue);
 
         /// <summary>
         /// Verifies and converts keyframe values according to this class's target type.
         /// </summary>
-        private void VerifyConvertKeyFrames(Type type)
+        private void VerifyConvertKeyFrames(Animation animation, Type type)
         {
             var typeConv = TypeDescriptor.GetConverter(type);
 
@@ -141,10 +134,10 @@ namespace Avalonia.Animation
 
                 if (k.timeSpanSet)
                 {
-                    _normalizedCue = new Cue(k.KeyTime.Ticks / _animation.Duration.Ticks);
+                    _normalizedCue = new Cue(k.KeyTime.Ticks / animation.Duration.Ticks);
                 }
 
-                _convertedKeyframes.Add(_normalizedCue.CueValue, convertedValue);
+                _convertedKeyframes.Add(_normalizedCue.CueValue, (convertedValue, false));
             }
 
             SortKeyFrameCues(_convertedKeyframes);
@@ -152,11 +145,12 @@ namespace Avalonia.Animation
 
         }
 
-        private void SortKeyFrameCues(Dictionary<double, T> convertedValues)
+        private void SortKeyFrameCues(Dictionary<double, (T, bool)> convertedValues)
         {
             bool hasStartKey, hasEndKey;
             hasStartKey = hasEndKey = false;
 
+            // Make start and end keyframe mandatory.
             foreach (var converted in _convertedKeyframes.Keys)
             {
                 if (DoubleUtils.AboutEqual(converted, 0.0))
@@ -170,25 +164,24 @@ namespace Avalonia.Animation
             }
 
             if (!hasStartKey || !hasEndKey)
-                AddNeutralKeyFrames(hasStartKey, hasEndKey);
+                AddNeutralKeyFrames(hasStartKey, hasEndKey, _convertedKeyframes);
 
             _convertedKeyframes = _convertedKeyframes.OrderBy(p => p.Key)
                                                      .ToDictionary((k) => k.Key, (v) => v.Value);
         }
 
-        private void AddNeutralKeyFrames(bool hasStartKey, bool hasEndKey)
+        private void AddNeutralKeyFrames(bool hasStartKey, bool hasEndKey, Dictionary<double, (T, bool)> convertedKeyframes)
         {
-            var neutralValue = (T)_target.GetValue(Property);
-
             if (!hasStartKey)
             {
-                _convertedKeyframes.Add(0.0d, neutralValue);
+                convertedKeyframes.Add(0.0d, (default(T), true));
             }
 
             if (!hasEndKey)
             {
-                _convertedKeyframes.Add(1.0d, neutralValue);
+                convertedKeyframes.Add(1.0d, (default(T), true));
             }
         }
+
     }
 }
\ No newline at end of file
diff --git a/src/Avalonia.Visuals/Animation/TransformKeyFrames.cs b/src/Avalonia.Visuals/Animation/TransformKeyFrames.cs
index 1adba63b40..dc803f0900 100644
--- a/src/Avalonia.Visuals/Animation/TransformKeyFrames.cs
+++ b/src/Avalonia.Visuals/Animation/TransformKeyFrames.cs
@@ -93,6 +93,6 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdocs/>
-        protected override double DoInterpolation(double time) => 0;
+        protected override double DoInterpolation(double time, double neutralValue) => 0;
     }
 }