Make SpeedRatio bindable.

src/Avalonia.Animation/Animation.cs

@@ -9,14 +9,21 @@ using System.Reactive.Linq;
 using System.Threading.Tasks;
 using Avalonia.Animation.Easings;
 using Avalonia.Collections;
+using Avalonia.Metadata;
 
 namespace Avalonia.Animation
 {
     /// <summary>
     /// Tracks the progress of an animation.
     /// </summary>
-    public class Animation : AvaloniaList<KeyFrame>, IAnimation
+    public class Animation : AvaloniaObject, IAnimation
     {
+        /// <summary>
+        /// Gets the children of the <see cref="Animation"/>.
+        /// </summary>
+        [Content]
+        public KeyFrames Children { get; } = new KeyFrames();
+
         /// <summary>
         /// Gets or sets the active time of this animation.
         /// </summary>
@@ -42,10 +49,6 @@ namespace Avalonia.Animation
         /// </summary>
         public Easing Easing { get; set; } = new LinearEasing();
 
-        /// <summary>
-        /// Gets or sets the speed multiple for this animation.
-        /// </summary>
-        public double SpeedRatio { get; set; } = 1d;
 
         /// <summary> 
         /// Gets or sets the delay time for this animation. 
@@ -61,6 +64,24 @@ namespace Avalonia.Animation
         /// </summary> 
         public TimeSpan DelayBetweenIterations { get; set; } = TimeSpan.Zero;
 
+        public static readonly DirectProperty<Animation, double> SpeedRatioProperty =
+                                AvaloniaProperty.RegisterDirect<Animation, double>(
+                                    nameof(_speedRatio),
+                                    o => o._speedRatio,
+                                    (o, v) => o._speedRatio = v,
+                                    1d);
+
+        private double _speedRatio = 1d;
+
+        /// <summary>
+        /// Gets or sets the speed multiple for this animation.
+        /// </summary> 
+        public double SpeedRatio
+        {
+            get { return _speedRatio; }
+            set { SetAndRaise(SpeedRatioProperty, ref _speedRatio, value); }
+        }
+
         private readonly static List<(Func<AvaloniaProperty, bool> Condition, Type Animator)> Animators = new List<(Func<AvaloniaProperty, bool>, Type)>
         {
             ( prop => typeof(double).IsAssignableFrom(prop.PropertyType), typeof(DoubleAnimator) )
@@ -90,7 +111,7 @@ namespace Avalonia.Animation
             var animatorKeyFrames = new List<AnimatorKeyFrame>();
             var subscriptions = new List<IDisposable>();
 
-            foreach (var keyframe in this)
+            foreach (var keyframe in Children)
             {
                 foreach (var setter in keyframe)
                 {

src/Avalonia.Animation/AnimationInstance`1.cs

@@ -30,7 +30,7 @@ namespace Avalonia.Animation
         private Easings.Easing _easeFunc;
         private Action _onCompleteAction;
         private Func<double, T, T> _interpolator;
-        private IDisposable _timerSubscription;
+        private IDisposable _timerSub, _speedRatioSub;
         private readonly IClock _baseClock;
         private IClock _clock;
 
@@ -47,7 +47,8 @@ namespace Avalonia.Animation
             _targetControl = control;
             _neutralValue = (T)_targetControl.GetValue(_parent.Property);
 
-            _speedRatio = animation.SpeedRatio;
+            _speedRatioSub = animation.GetObservable(Animation.SpeedRatioProperty)
+                                      .Subscribe(p => _speedRatio = p);
 
             _initialDelay = animation.Delay;
             _duration = animation.Duration;
@@ -57,7 +58,7 @@ namespace Avalonia.Animation
             {
                 case RepeatType.None:
                     _iterationCount = 1;
-                    break; 
+                    break;
                 case RepeatType.Repeat:
                     _iterationCount = animation.RepeatCount.Value;
                     break;
@@ -75,14 +76,15 @@ namespace Avalonia.Animation
             // Animation may have been stopped before it has finished.
             ApplyFinalFill();
 
-            _timerSubscription?.Dispose();
+            _timerSub?.Dispose();
+            _speedRatioSub?.Dispose();
             _clock.PlayState = PlayState.Stop;
         }
 
         protected override void Subscribed()
         {
             _clock = new Clock(_baseClock);
-            _timerSubscription = _clock.Subscribe(Step);
+            _timerSub = _clock.Subscribe(Step);
         }
 
         public void Step(TimeSpan frameTick)
@@ -134,7 +136,7 @@ namespace Avalonia.Animation
         private void InternalStep(TimeSpan time)
         {
             DoPlayStates();
-            
+
             // Scale timebases according to speedratio.
             var indexTime = time.Ticks;
             var iterDuration = _duration.Ticks * _speedRatio;
@@ -153,7 +155,7 @@ namespace Avalonia.Animation
                 var playbackTime = opsTime % iterationTime;
 
                 _currentIteration = (ulong)(opsTime / iterationTime);
-                
+
                 // Stop animation when the current iteration is beyond the iteration count.
                 if ((_currentIteration + 1) > _iterationCount)
                     DoComplete();
@@ -178,7 +180,7 @@ namespace Avalonia.Animation
                     PublishNext(_lastInterpValue);
                 }
                 else if (playbackTime > iterDuration &
-                         playbackTime <= iterationTime & 
+                         playbackTime <= iterationTime &
                          iterDelay > 0 &
                          // The last iteration's trailing delay should be skipped.
                          (_currentIteration + 1) < _iterationCount)

src/Avalonia.Animation/KeyFrames.cs

@@ -0,0 +1,33 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Collections.Generic;
+using Avalonia.Collections;
+
+namespace Avalonia.Animation
+{
+    /// <summary>
+    /// A collection of <see cref="KeyFrame"/>s.
+    /// </summary>
+    public class KeyFrames : AvaloniaList<KeyFrame>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="KeyFrames"/> class.
+        /// </summary>
+        public KeyFrames()
+        {
+            ResetBehavior = ResetBehavior.Remove;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="KeyFrames"/> class.
+        /// </summary>
+        /// <param name="items">The initial items in the collection.</param>
+        public KeyFrames(IEnumerable<KeyFrame> items)
+            : base(items)
+        {
+            ResetBehavior = ResetBehavior.Remove;
+        }
+    }
+}

src/Avalonia.Visuals/Animation/CrossFade.cs

@@ -21,7 +21,7 @@ namespace Avalonia.Animation
         /// Initializes a new instance of the <see cref="CrossFade"/> class.
         /// </summary>
         public CrossFade()
-            :this(TimeSpan.Zero)
+            : this(TimeSpan.Zero)
         {
         }
 
@@ -33,30 +33,36 @@ namespace Avalonia.Animation
         {
             _fadeOutAnimation = new Animation
             {
-                new KeyFrame
-                (
-                    new Setter
+                Children  = 
+                {
+                    new KeyFrame
+                    (
+                        new Setter
+                        {
+                            Property = Visual.OpacityProperty,
+                            Value = 0d
+                        }
+                    )
                     {
-                        Property = Visual.OpacityProperty,
-                        Value = 0d
+                        Cue = new Cue(1d)
                     }
-                )
-                {
-                    Cue = new Cue(1d)
                 }
             };
             _fadeInAnimation = new Animation
             {
-                new KeyFrame
-                (
-                    new Setter
+                Children = 
+                {
+                    new KeyFrame
+                    (
+                        new Setter
+                        {
+                            Property = Visual.OpacityProperty,
+                            Value = 0d
+                        }
+                    )
                     {
-                        Property = Visual.OpacityProperty,
-                        Value = 0d
+                        Cue = new Cue(0d)
                     }
-                )
-                {
-                    Cue = new Cue(0d)
                 }
             };
             _fadeOutAnimation.Duration = _fadeInAnimation.Duration = duration;

src/Avalonia.Visuals/Animation/PageSlide.cs

@@ -74,34 +74,34 @@ namespace Avalonia.Animation
             var distance = Orientation == SlideAxis.Horizontal ? parent.Bounds.Width : parent.Bounds.Height;
             var translateProperty = Orientation == SlideAxis.Horizontal ? TranslateTransform.XProperty : TranslateTransform.YProperty;
 
-
-            // TODO: Implement relevant transition logic here (or discard this class)
-            // in favor of XAML based transition for pages
             if (from != null)
             {
                 var animation = new Animation
                 {
-                    new KeyFrame
-                    (
-                        new Setter
-                        {
-                            Property = translateProperty,
-                            Value = 0d
-                        }
-                    )
+                    Children = 
                     {
-                        Cue = new Cue(0d)
-                    },
-                    new KeyFrame
-                    (
-                        new Setter
+                        new KeyFrame
+                        (
+                            new Setter
+                            {
+                                Property = translateProperty,
+                                Value = 0d
+                            }
+                        )
                         {
-                            Property = translateProperty,
-                            Value = forward ? -distance : distance
+                            Cue = new Cue(0d)
+                        },
+                        new KeyFrame
+                        (
+                            new Setter
+                            {
+                                Property = translateProperty,
+                                Value = forward ? -distance : distance
+                            }
+                        )
+                        {
+                            Cue = new Cue(1d)
                         }
-                    )
-                    {
-                        Cue = new Cue(1d)
                     }
                 };
                 animation.Duration = Duration;
@@ -113,29 +113,31 @@ namespace Avalonia.Animation
                 to.IsVisible = true;
                 var animation = new Animation
                 {
-
-                    new KeyFrame
-                    (
-                        new Setter
-                        {
-                            Property = translateProperty,
-                            Value = forward ? distance : -distance
-                        }
-                    )
+                    Children =
                     {
-                        Cue = new Cue(0d)
-                    },
-                    new KeyFrame
-                    (
-                        new Setter
+                        new KeyFrame
+                        (
+                            new Setter
+                            {
+                                Property = translateProperty,
+                                Value = forward ? distance : -distance
+                            }
+                        )
                         {
-                            Property = translateProperty,
-                            Value = 0d
-                        }
-                    )
-                    {
-                        Cue = new Cue(1d)
-                    },
+                            Cue = new Cue(0d)
+                        },
+                        new KeyFrame
+                        (
+                            new Setter
+                            {
+                                Property = translateProperty,
+                                Value = 0d
+                            }
+                        )
+                        {
+                            Cue = new Cue(1d)
+                        },
+                    }
                 };
                 animation.Duration = Duration;
                 tasks.Add(animation.RunAsync(to));