Enable Animations to run on a non-global clock.

src/Avalonia.Animation/Animation.cs

@@ -154,12 +154,12 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdocs/>
-        public IDisposable Apply(Animatable control, IObservable<bool> match, Action onComplete)
+        public IDisposable Apply(Animatable control, Clock clock, IObservable<bool> match, Action onComplete)
         {
             var (animators, subscriptions) = InterpretKeyframes(control);
             if (animators.Count == 1)
             {
-                subscriptions.Add(animators[0].Apply(this, control, match, onComplete));
+                subscriptions.Add(animators[0].Apply(this, control, clock, match, onComplete));
             }
             else
             {
@@ -173,7 +173,7 @@ namespace Avalonia.Animation
                         animatorOnComplete = () => tcs.SetResult(null);
                         completionTasks.Add(tcs.Task);
                     }
-                    subscriptions.Add(animator.Apply(this, control, match, animatorOnComplete));
+                    subscriptions.Add(animator.Apply(this, control, clock, match, animatorOnComplete));
                 }
 
                 if (onComplete != null)
@@ -185,15 +185,20 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdocs/>
-        public Task RunAsync(Animatable control)
+        public Task RunAsync(Animatable control, Clock clock = null)
         {
+            if (clock == null)
+            {
+                clock = Clock.GlobalClock;
+            }
+
             var run = new TaskCompletionSource<object>();
 
             if (this.RepeatCount == RepeatCount.Loop)
                 run.SetException(new InvalidOperationException("Looping animations must not use the Run method."));
 
             IDisposable subscriptions = null;
-            subscriptions = this.Apply(control, Observable.Return(true), () =>
+            subscriptions = this.Apply(control, clock, Observable.Return(true), () =>
             {
                 run.SetResult(null);
                 subscriptions?.Dispose();

src/Avalonia.Animation/AnimationInstance`1.cs

@@ -34,8 +34,9 @@ namespace Avalonia.Animation
         private Action _onCompleteAction;
         private Func<double, T, T> _interpolator;
         private IDisposable _timerSubscription;
+        private readonly Clock _clock;
 
-        public AnimationInstance(Animation animation, Animatable control, Animator<T> animator, Action OnComplete, Func<double, T, T> Interpolator)
+        public AnimationInstance(Animation animation, Animatable control, Animator<T> animator, Clock clock, Action OnComplete, Func<double, T, T> Interpolator)
         {
             if (animation.SpeedRatio <= 0)
                 throw new InvalidOperationException("Speed ratio cannot be negative or zero.");
@@ -71,6 +72,7 @@ namespace Avalonia.Animation
             _fillMode = animation.FillMode;
             _onCompleteAction = OnComplete;
             _interpolator = Interpolator;
+            _clock = clock;
         }
 
         protected override void Unsubscribed()
@@ -80,7 +82,7 @@ namespace Avalonia.Animation
 
         protected override void Subscribed()
         {
-            _timerSubscription = Clock.GlobalClock.Subscribe(Step);
+            _timerSubscription = _clock.Subscribe(Step);
         }
 
         public void Step(TimeSpan frameTick)
@@ -115,7 +117,7 @@ namespace Avalonia.Animation
 
         private void DoPlayStatesAndTime(TimeSpan systemTime)
         {
-            if (Animation.GlobalPlayState == PlayState.Stop || _targetControl.PlayState == PlayState.Stop)
+            if (_clock.PlayState == PlayState.Stop || _targetControl.PlayState == PlayState.Stop)
                 DoComplete();
 
             if (!_gotFirstKFValue)

src/Avalonia.Animation/Animator`1.cs

@@ -32,7 +32,7 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdoc/>
-        public virtual IDisposable Apply(Animation animation, Animatable control, IObservable<bool> match, Action onComplete)
+        public virtual IDisposable Apply(Animation animation, Animatable control, Clock clock, IObservable<bool> match, Action onComplete)
         {
              if (!_isVerifiedAndConverted)
                 VerifyConvertKeyFrames();
@@ -41,7 +41,7 @@ namespace Avalonia.Animation
                 .Where(p => p)
                 .Subscribe(_ =>
                 {
-                    var timerObs = RunKeyFrames(animation, control, onComplete);
+                    var timerObs = RunKeyFrames(animation, control, clock, onComplete);
                 });
         }
 
@@ -101,9 +101,9 @@ namespace Avalonia.Animation
         /// <summary>
         /// Runs the KeyFrames Animation.
         /// </summary>
-        private IDisposable RunKeyFrames(Animation animation, Animatable control, Action onComplete)
+        private IDisposable RunKeyFrames(Animation animation, Animatable control, Clock clock, Action onComplete)
         {
-            var instance = new AnimationInstance<T>(animation, control, this, onComplete, DoInterpolation);
+            var instance = new AnimationInstance<T>(animation, control, this, clock, onComplete, DoInterpolation);
             return control.Bind<T>((AvaloniaProperty<T>)Property, instance, BindingPriority.Animation);
         }
 

src/Avalonia.Animation/Clock.cs

@@ -58,6 +58,16 @@ namespace Avalonia.Animation
 
             _observable.Pulse(_internalTime);
             CurrentTime = _internalTime;
+
+            if (PlayState == PlayState.Stop)
+            {
+                Stop();
+            }
+        }
+
+        protected virtual void Stop()
+        {
+            _parentSubscription?.Dispose();
         }
 
         public IDisposable Subscribe(IObserver<TimeSpan> observer)

src/Avalonia.Animation/IAnimation.cs

@@ -11,11 +11,11 @@ namespace Avalonia.Animation
         /// <summary>
         /// Apply the animation to the specified control
         /// </summary>
-        IDisposable Apply(Animatable control, IObservable<bool> match, Action onComplete = null);
+        IDisposable Apply(Animatable control, Clock clock, IObservable<bool> match, Action onComplete = null);
 
         /// <summary>
         /// Run the animation to the specified control
         /// </summary>
-        Task RunAsync(Animatable control);
+        Task RunAsync(Animatable control, Clock clock);
     }
 }

src/Avalonia.Animation/IAnimator.cs

@@ -16,6 +16,6 @@ namespace Avalonia.Animation
         /// <summary>
         /// Applies the current KeyFrame group to the specified control.
         /// </summary>
-        IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete);
+        IDisposable Apply(Animation animation, Animatable control, Clock clock, IObservable<bool> obsMatch, Action onComplete);
     }
 }

src/Avalonia.Styling/Styling/Style.cs

@@ -120,7 +120,7 @@ namespace Avalonia.Styling
                             obsMatch = Observable.Return(true);
                         } 
 
-                        var sub = animation.Apply((Animatable)control, obsMatch);
+                        var sub = animation.Apply((Animatable)control, Clock.GlobalClock, obsMatch);
                         subs.Add(sub);
                     }
 

src/Avalonia.Visuals/Animation/RenderLoopClock.cs

@@ -7,6 +7,11 @@ namespace Avalonia.Animation
 {
     public class RenderLoopClock : Clock, IRenderLoopTask
     {
+        protected override void Stop()
+        {
+            AvaloniaLocator.Current.GetService<IRenderLoop>().Remove(this);
+        }
+
         bool IRenderLoopTask.NeedsUpdate => HasSubscriptions;
 
         void IRenderLoopTask.Render()

src/Avalonia.Visuals/Animation/TransformAnimator.cs

@@ -12,7 +12,7 @@ namespace Avalonia.Animation
         DoubleAnimator childKeyFrames;
 
         /// <inheritdoc/>
-        public override IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete)
+        public override IDisposable Apply(Animation animation, Animatable control, Clock clock, IObservable<bool> obsMatch, Action onComplete)
         {
             var ctrl = (Visual)control;
 
@@ -44,7 +44,7 @@ namespace Avalonia.Animation
                 // It's a transform object so let's target that.
                 if (renderTransformType == Property.OwnerType)
                 {
-                    return childKeyFrames.Apply(animation, ctrl.RenderTransform, obsMatch, onComplete);
+                    return childKeyFrames.Apply(animation, ctrl.RenderTransform, clock, obsMatch, onComplete);
                 }
                 // It's a TransformGroup and try finding the target there.
                 else if (renderTransformType == typeof(TransformGroup))
@@ -53,7 +53,7 @@ namespace Avalonia.Animation
                     {
                         if (transform.GetType() == Property.OwnerType)
                         {
-                            return childKeyFrames.Apply(animation, transform, obsMatch, onComplete);
+                            return childKeyFrames.Apply(animation, transform, clock, obsMatch, onComplete);
                         }
                     }
                 }