Merge pull request #5886 from AvaloniaUI/animations/tryfix-scb-localvalue

Revamp IBrush animator selection + Stop SCBAnimator from setting localvalues on animation apply

src/Avalonia.Animation/Animation.cs

@@ -209,6 +209,17 @@ namespace Avalonia.Animation
             ( prop => typeof(decimal).IsAssignableFrom(prop.PropertyType), typeof(DecimalAnimator) ),
         };
 
+        /// <summary>
+        /// Registers a <see cref="Animator{T}"/> that can handle
+        /// a value type that matches the specified condition.
+        /// </summary>
+        /// <param name="condition">
+        /// The condition to which the <see cref="Animator{T}"/>
+        /// is to be activated and used.
+        /// </param>
+        /// <typeparam name="TAnimator">
+        /// The type of the animator to instantiate.
+        /// </typeparam>
         public static void RegisterAnimator<TAnimator>(Func<AvaloniaProperty, bool> condition)
             where TAnimator : IAnimator
         {

src/Avalonia.Animation/Animators/Animator`1.cs

@@ -104,6 +104,11 @@ namespace Avalonia.Animation.Animators
             throw new Exception("Index time is out of keyframe time range.");
         }
 
+        public virtual IDisposable BindAnimation(Animatable control, IObservable<T> instance)
+        {
+            return control.Bind((AvaloniaProperty<T>)Property, instance, BindingPriority.Animation);
+        }
+
         /// <summary>
         /// Runs the KeyFrames Animation.
         /// </summary>
@@ -116,7 +121,8 @@ namespace Avalonia.Animation.Animators
                 clock ?? control.Clock ?? Clock.GlobalClock,
                 onComplete,
                 InterpolationHandler);
-            return control.Bind<T>((AvaloniaProperty<T>)Property, instance, BindingPriority.Animation);
+            
+            return BindAnimation(control, instance);
         }
 
         /// <summary>

src/Avalonia.Visuals/Animation/Animators/BaseBrushAnimator.cs

@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+using System.Reactive.Disposables;
+using Avalonia.Logging;
+using Avalonia.Media;
+
+namespace Avalonia.Animation.Animators
+{
+    /// <summary>
+    /// Animator that handles all animations on properties
+    /// with <see cref="IBrush"/> as their type and
+    /// redirect them to the properly registered
+    /// animators in this class.
+    /// </summary>
+    public class BaseBrushAnimator : Animator<IBrush>
+    {
+        private IAnimator _targetAnimator;
+
+        private static readonly List<(Func<Type, bool> Match, Type AnimatorType)> _brushAnimators =
+            new List<(Func<Type, bool> Match, Type AnimatorType)>();
+
+        /// <summary>
+        /// Register an <see cref="Animator{T}"/> that handles a specific
+        /// <see cref="IBrush"/>'s descendant value type.
+        /// </summary>
+        /// <param name="condition">
+        /// The condition to which the <see cref="Animator{T}"/>
+        /// is to be activated and used.
+        /// </param>
+        /// <typeparam name="TAnimator">
+        /// The type of the animator to instantiate.
+        /// </typeparam>
+        public static void RegisterBrushAnimator<TAnimator>(Func<Type, bool> condition)
+            where TAnimator : IAnimator
+        {
+            _brushAnimators.Insert(0, (condition, typeof(TAnimator)));
+        }
+
+        /// <inheritdoc/>
+        public override IDisposable Apply(Animation animation, Animatable control, IClock clock,
+            IObservable<bool> match, Action onComplete)
+        {
+            foreach (var valueType in _brushAnimators)
+            {
+                if (!valueType.Match(this[0].Value.GetType())) continue;
+
+                _targetAnimator = (IAnimator)Activator.CreateInstance(valueType.AnimatorType);
+
+                foreach (var keyframe in this)
+                {
+                    _targetAnimator.Add(keyframe);
+                }
+
+                _targetAnimator.Property = this.Property;
+                
+               return _targetAnimator.Apply(animation, control, clock, match, onComplete);
+            }
+
+            Logger.TryGet(LogEventLevel.Error, LogArea.Animations)?.Log(
+                this,
+                "The animation's keyframe values didn't match any brush animators registered in BaseBrushAnimator.");
+            
+            return Disposable.Empty;
+        }
+
+        /// <inheritdoc/>
+        public override IBrush Interpolate(double progress, IBrush oldValue, IBrush newValue) => null;
+    }
+}

src/Avalonia.Visuals/Animation/Animators/ColorAnimator.cs

@@ -31,6 +31,11 @@ namespace Avalonia.Animation.Animators
         }
 
         public override Color Interpolate(double progress, Color oldValue, Color newValue)
+        {
+            return InterpolateCore(progress, oldValue, newValue);
+        }
+
+        internal static Color InterpolateCore(double progress, Color oldValue, Color newValue)
         {
             // normalize sRGB values.
             var oldA = oldValue.A / 255d;
@@ -59,7 +64,7 @@ namespace Avalonia.Animation.Animators
             var b = oldB + progress * (newB - oldB);
 
             // convert back to sRGB in the [0..255] range
-            a = a * 255d;
+            a *= 255d;
             r = OECF_sRGB(r) * 255d;
             g = OECF_sRGB(g) * 255d;
             b = OECF_sRGB(b) * 255d;

src/Avalonia.Visuals/Animation/Animators/SolidColorBrushAnimator.cs

@@ -1,71 +1,32 @@
 using System;
-using System.Reactive.Disposables;
+using Avalonia.Data;
 using Avalonia.Media;
 using Avalonia.Media.Immutable;
 
 namespace Avalonia.Animation.Animators
 {
     /// <summary>
-    /// Animator that handles <see cref="SolidColorBrush"/>. 
+    /// Animator that handles <see cref="SolidColorBrush"/> values. 
     /// </summary>
-    public class SolidColorBrushAnimator : Animator<SolidColorBrush>
+    public class ISolidColorBrushAnimator : Animator<ISolidColorBrush>
     {
-        private ColorAnimator _colorAnimator;
-
-        private void InitializeColorAnimator()
+        public override ISolidColorBrush Interpolate(double progress, ISolidColorBrush oldValue, ISolidColorBrush newValue)
         {
-            _colorAnimator = new ColorAnimator();
-
-            foreach (AnimatorKeyFrame keyframe in this)
-            {
-                _colorAnimator.Add(keyframe);
-            }
-
-            _colorAnimator.Property = SolidColorBrush.ColorProperty;
+            return new ImmutableSolidColorBrush(ColorAnimator.InterpolateCore(progress, oldValue.Color, newValue.Color));
         }
 
-        public override IDisposable Apply(Animation animation, Animatable control, IClock clock, IObservable<bool> match, Action onComplete)
+        public override IDisposable BindAnimation(Animatable control, IObservable<ISolidColorBrush> instance)
         {
-            // Preprocess keyframe values to Color if the xaml parser converts them to ISCB.
-            foreach (var keyframe in this)
-            {
-                if (keyframe.Value is ISolidColorBrush colorBrush)
-                {
-                    keyframe.Value = colorBrush.Color;
-                }
-                else
-                {
-                    return Disposable.Empty;
-                }
-            }
-
-            SolidColorBrush finalTarget;
-            var targetVal = control.GetValue(Property);
-            if (targetVal is null)
-            {
-                finalTarget = new SolidColorBrush(Colors.Transparent);
-                control.SetValue(Property, finalTarget);
-            }
-            else if (targetVal is ImmutableSolidColorBrush immutableSolidColorBrush)
-            {
-                finalTarget = new SolidColorBrush(immutableSolidColorBrush.Color);
-                control.SetValue(Property, finalTarget);
-            }
-            else if (targetVal is ISolidColorBrush)
-            {
-                finalTarget = targetVal as SolidColorBrush;
-            }
-            else
-            {
-                return Disposable.Empty;
-            }
-
-            if (_colorAnimator == null)
-                InitializeColorAnimator();
-
-            return _colorAnimator.Apply(animation, finalTarget, clock ?? control.Clock, match, onComplete);
+            return control.Bind((AvaloniaProperty<IBrush>)Property, instance, BindingPriority.Animation);
+        }
+    }
+    
+    [Obsolete]    
+    public class SolidColorBrushAnimator : Animator<SolidColorBrush>
+    {    
+        public override SolidColorBrush Interpolate(double progress, SolidColorBrush oldValue, SolidColorBrush newValue)
+        {
+            return new SolidColorBrush(ColorAnimator.InterpolateCore(progress, oldValue.Color, newValue.Color));
         }
-
-        public override SolidColorBrush Interpolate(double p, SolidColorBrush o, SolidColorBrush n) => null;
     }
 }

src/Avalonia.Visuals/Media/Brush.cs

@@ -1,6 +1,7 @@
 using System;
 using System.ComponentModel;
 using Avalonia.Animation;
+using Avalonia.Animation.Animators;
 
 namespace Avalonia.Media
 {
@@ -21,6 +22,7 @@ namespace Avalonia.Media
 
         static Brush()
         {
+            Animation.Animation.RegisterAnimator<BaseBrushAnimator>(prop => typeof(IBrush).IsAssignableFrom(prop.PropertyType));
             AffectsRender<Brush>(OpacityProperty);
         }
 

src/Avalonia.Visuals/Media/SolidColorBrush.cs

@@ -1,4 +1,3 @@
-using Avalonia.Animation;
 using Avalonia.Animation.Animators;
 using Avalonia.Media.Immutable;
 
@@ -17,7 +16,7 @@ namespace Avalonia.Media
 
         static SolidColorBrush()
         {
-            Animation.Animation.RegisterAnimator<SolidColorBrushAnimator>(prop => typeof(IBrush).IsAssignableFrom(prop.PropertyType));
+            BaseBrushAnimator.RegisterBrushAnimator<ISolidColorBrushAnimator>(match => typeof(ISolidColorBrush).IsAssignableFrom(match));
             AffectsRender<SolidColorBrush>(ColorProperty);
         }