Merge pull request #1774 from AvaloniaUI/awaitablerun-animations

Code-behind Animation Trigger

src/Avalonia.Animation/Animation.cs

@@ -10,13 +10,16 @@ using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.Reflection;
 using System.Linq;
+using System.Threading.Tasks;
+using System.Reactive.Linq;
+using System.Reactive.Disposables;
 
 namespace Avalonia.Animation
 {
     /// <summary>
     /// Tracks the progress of an animation.
     /// </summary>
-    public class Animation : AvaloniaList<KeyFrame>, IDisposable, IAnimation
+    public class Animation : AvaloniaList<KeyFrame>, IAnimation
     {
         private readonly static List<(Func<AvaloniaProperty, bool> Condition, Type Animator)> Animators = new List<(Func<AvaloniaProperty, bool>, Type)>
         {
@@ -24,7 +27,7 @@ namespace Avalonia.Animation
         };
 
         public static void RegisterAnimator<TAnimator>(Func<AvaloniaProperty, bool> condition)
-            where TAnimator: IAnimator
+            where TAnimator : IAnimator
         {
             Animators.Insert(0, (condition, typeof(TAnimator)));
         }
@@ -41,8 +44,6 @@ namespace Avalonia.Animation
             return null;
         }
 
-        private bool _isChildrenChanged = false;
-        private List<IDisposable> _subscription = new List<IDisposable>();
         public AvaloniaList<IAnimator> _animators { get; set; } = new AvaloniaList<IAnimator>();
 
         /// <summary>
@@ -72,18 +73,14 @@ namespace Avalonia.Animation
 
         /// <summary>
         /// Easing function to be used.
-        /// </summary> 
+        /// </summary>
         public Easing Easing { get; set; } = new LinearEasing();
 
-        public Animation()
-        {
-            this.CollectionChanged += delegate { _isChildrenChanged = true; };
-        }
- 
-        private IList<IAnimator> InterpretKeyframes(Animatable control)
+        private (IList<IAnimator> Animators, IList<IDisposable> subscriptions) InterpretKeyframes(Animatable control)
         {
             var handlerList = new List<(Type type, AvaloniaProperty property)>();
             var animatorKeyFrames = new List<AnimatorKeyFrame>();
+            var subscriptions = new List<IDisposable>();
 
             foreach (var keyframe in this)
             {
@@ -108,7 +105,7 @@ namespace Avalonia.Animation
 
                     var newKF = new AnimatorKeyFrame(handler, cue);
 
-                    _subscription.Add(newKF.BindSetter(setter, control));
+                    subscriptions.Add(newKF.BindSetter(setter, control));
 
                     animatorKeyFrames.Add(newKF);
                 }
@@ -130,28 +127,56 @@ namespace Avalonia.Animation
                 animator.Add(keyframe);
             }
 
-            return newAnimatorInstances;
+            return (newAnimatorInstances, subscriptions);
         }
 
-        /// <summary>
-        /// Cancels the animation.
-        /// </summary>
-        public void Dispose()
+        /// <inheritdocs/>
+        public IDisposable Apply(Animatable control, IObservable<bool> match, Action onComplete)
         {
-            foreach (var sub in _subscription)
+            var (animators, subscriptions) = InterpretKeyframes(control);
+            if (animators.Count == 1)
             {
-                sub.Dispose();
+                subscriptions.Add(animators[0].Apply(this, control, match, onComplete));
             }
+            else
+            {
+                var completionTasks = onComplete != null ? new List<Task>() : null;
+                foreach (IAnimator animator in animators)
+                {
+                    Action animatorOnComplete = null;
+                    if (onComplete != null)
+                    {
+                        var tcs = new TaskCompletionSource<object>();
+                        animatorOnComplete = () => tcs.SetResult(null);
+                        completionTasks.Add(tcs.Task);
+                    }
+                    subscriptions.Add(animator.Apply(this, control, match, animatorOnComplete));
+                }
+
+                if (onComplete != null)
+                {
+                    Task.WhenAll(completionTasks).ContinueWith(_ => onComplete());
+                }
+            }
+            return new CompositeDisposable(subscriptions);
         }
 
         /// <inheritdocs/>
-        public IDisposable Apply(Animatable control, IObservable<bool> matchObs)
+        public Task RunAsync(Animatable control)
         {
-            foreach (IAnimator animator in InterpretKeyframes(control))
+            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), () =>
             {
-                _subscription.Add(animator.Apply(this, control, matchObs));
-            }
-            return this;
+                run.SetResult(null);
+                subscriptions?.Dispose();
+            });
+
+            return run.Task;
         }
     }
 }

src/Avalonia.Animation/AnimatorKeyFrame.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Animation
     public class AnimatorKeyFrame : AvaloniaObject
     {
         public static readonly DirectProperty<AnimatorKeyFrame, object> ValueProperty =
-            AvaloniaProperty.RegisterDirect<AnimatorKeyFrame, object>(nameof(Value), k => k._value, (k, v) => k._value = v);
+            AvaloniaProperty.RegisterDirect<AnimatorKeyFrame, object>(nameof(Value), k => k.Value, (k, v) => k.Value = v);
 
         public AnimatorKeyFrame()
         {

src/Avalonia.Animation/AnimatorStateMachine`1.cs

@@ -35,6 +35,7 @@ namespace Avalonia.Animation
         private T _neutralValue;
         internal bool _unsubscribe = false;
         private IObserver<object> _targetObserver;
+        private readonly Action _onComplete;
 
         [Flags]
         private enum KeyFramesStates
@@ -51,7 +52,7 @@ namespace Avalonia.Animation
             Disposed
         }
 
-        public void Initialize(Animation animation, Animatable control, Animator<T> animator)
+        public AnimatorStateMachine(Animation animation, Animatable control, Animator<T> animator, Action onComplete)
         {
             _parent = animator;
             _targetAnimation = animation;
@@ -82,6 +83,7 @@ namespace Avalonia.Animation
                 _currentState = KeyFramesStates.DoDelay;
             else
                 _currentState = KeyFramesStates.DoRun;
+            _onComplete = onComplete;
         }
 
         public void Step(PlayState _playState, Func<double, T, T> Interpolator)
@@ -243,7 +245,10 @@ namespace Avalonia.Animation
                         {
                             _targetControl.SetValue(_parent.Property, _lastInterpValue, BindingPriority.LocalValue);
                         }
+
                         _targetObserver.OnCompleted();
+                        _onComplete?.Invoke();
+                        Dispose();
                         handled = true;
                         break;
                     default:

src/Avalonia.Animation/Animator`1.cs

@@ -35,7 +35,7 @@ namespace Avalonia.Animation
         }
 
         /// <inheritdoc/>
-        public virtual IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch)
+        public virtual IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete)
         {
             if (!_isVerfifiedAndConverted)
                 VerifyConvertKeyFrames();
@@ -45,7 +45,7 @@ namespace Avalonia.Animation
                 .Where(p => p && Timing.GetGlobalPlayState() != PlayState.Pause)
                 .Subscribe(_ =>
                 {
-                    var timerObs = RunKeyFrames(animation, control);
+                    var timerObs = RunKeyFrames(animation, control, onComplete);
                 });
         }
 
@@ -97,10 +97,9 @@ namespace Avalonia.Animation
         /// <summary>
         /// Runs the KeyFrames Animation.
         /// </summary>
-        private IDisposable RunKeyFrames(Animation animation, Animatable control)
+        private IDisposable RunKeyFrames(Animation animation, Animatable control, Action onComplete)
         {
-            var stateMachine = new AnimatorStateMachine<T>();
-            stateMachine.Initialize(animation, control, this);
+            var stateMachine = new AnimatorStateMachine<T>(animation, control, this, onComplete);
 
             Timing.AnimationStateTimer
                         .TakeWhile(_ => !stateMachine._unsubscribe)

src/Avalonia.Animation/IAnimation.cs

@@ -1,6 +1,7 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Text;
+using System.Threading.Tasks;
 
 namespace Avalonia.Animation
 {
@@ -12,6 +13,11 @@ namespace Avalonia.Animation
         /// <summary>
         /// Apply the animation to the specified control
         /// </summary>
-        IDisposable Apply(Animatable control, IObservable<bool> match);
+        IDisposable Apply(Animatable control, IObservable<bool> match, Action onComplete = null);
+
+        /// <summary>
+        /// Run the animation to the specified control
+        /// </summary>
+        Task RunAsync(Animatable control);
     }
 }

src/Avalonia.Animation/IAnimator.cs

@@ -17,6 +17,6 @@ namespace Avalonia.Animation
         /// <summary>
         /// Applies the current KeyFrame group to the specified control.
         /// </summary>
-        IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch);
+        IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete);
     }
 }

src/Avalonia.Visuals/Animation/TransformAnimator.cs

@@ -19,7 +19,7 @@ namespace Avalonia.Animation
         DoubleAnimator childKeyFrames;
 
         /// <inheritdoc/>
-        public override IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch)
+        public override IDisposable Apply(Animation animation, Animatable control, IObservable<bool> obsMatch, Action onComplete)
         {
             var ctrl = (Visual)control;
 
@@ -51,7 +51,7 @@ namespace Avalonia.Animation
                 // It's a transform object so let's target that.
                 if (renderTransformType == Property.OwnerType)
                 {
-                    return childKeyFrames.Apply(animation, ctrl.RenderTransform, obsMatch);
+                    return childKeyFrames.Apply(animation, ctrl.RenderTransform, obsMatch, onComplete);
                 }
                 // It's a TransformGroup and try finding the target there.
                 else if (renderTransformType == typeof(TransformGroup))
@@ -60,7 +60,7 @@ namespace Avalonia.Animation
                     {
                         if (transform.GetType() == Property.OwnerType)
                         {
-                            return childKeyFrames.Apply(animation, transform, obsMatch);
+                            return childKeyFrames.Apply(animation, transform, obsMatch, onComplete);
                         }
                     }
                 }