Make Animation.RunAsync cancellable

src/Avalonia.Animation/Animation.cs

@@ -3,10 +3,11 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Disposables;
 using System.Reactive.Linq;
+using System.Threading;
 using System.Threading.Tasks;
+
 using Avalonia.Animation.Animators;
 using Avalonia.Animation.Easings;
-using Avalonia.Collections;
 using Avalonia.Data;
 using Avalonia.Metadata;
 
@@ -292,7 +293,7 @@ namespace Avalonia.Animation
             return (newAnimatorInstances, subscriptions);
         }
 
-        /// <inheritdocs/>
+        /// <inheritdoc/>
         public IDisposable Apply(Animatable control, IClock clock, IObservable<bool> match, Action onComplete)
         {
             var (animators, subscriptions) = InterpretKeyframes(control);
@@ -323,21 +324,24 @@ namespace Avalonia.Animation
             return new CompositeDisposable(subscriptions);
         }
 
-        /// <inheritdocs/>
-        public Task RunAsync(Animatable control, IClock clock = null)
+        /// <inheritdoc/>
+        public Task RunAsync(Animatable control, IClock clock = null, CancellationToken cancellationToken = default)
         {
             var run = new TaskCompletionSource<object>();
 
             if (this.IterationCount == IterationCount.Infinite)
                 run.SetException(new InvalidOperationException("Looping animations must not use the Run method."));
 
-            IDisposable subscriptions = null;
+            IDisposable subscriptions = null, cancellation = null;
             subscriptions = this.Apply(control, clock, Observable.Return(true), () =>
             {
                 run.SetResult(null);
                 subscriptions?.Dispose();
+                cancellation?.Dispose();
             });
 
+            cancellation = cancellationToken.Register(state => ((IDisposable)state).Dispose(), subscriptions);
+
             return run.Task;
         }
     }

src/Avalonia.Animation/ApiCompatBaseline.txt

@@ -0,0 +1,6 @@
+Compat issues with assembly Avalonia.Animation:
+MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.Animation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock)' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Tasks.Task Avalonia.Animation.IAnimation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock)' is present in the contract but not in the implementation.
+MembersMustExist : Member 'public System.Threading.Tasks.Task Avalonia.Animation.IAnimation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock)' does not exist in the implementation but it does exist in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Threading.Tasks.Task Avalonia.Animation.IAnimation.RunAsync(Avalonia.Animation.Animatable, Avalonia.Animation.IClock, System.Threading.CancellationToken)' is present in the implementation but not in the contract.
+Total Issues: 4

src/Avalonia.Animation/IAnimation.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace Avalonia.Animation
@@ -16,6 +17,6 @@ namespace Avalonia.Animation
         /// <summary>
         /// Run the animation on the specified control.
         /// </summary>
-        Task RunAsync(Animatable control, IClock clock);
+        Task RunAsync(Animatable control, IClock clock, CancellationToken cancellationToken);
     }
 }