Clean-up ShadowAnimation type and add rest of animatable properties

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/XamlOnlyPage.xaml

@@ -66,7 +66,10 @@
                 <ani:SaturationEffectAnimation />
                 <ani:AnimationScope />
                 <ani:ExposureEffectAnimation />
+                <ani:BlurRadiusDropShadowAnimation />
+                <ani:ColorDropShadowAnimation />
                 <ani:OffsetDropShadowAnimation />
+                <ani:OpacityDropShadowAnimation />
             </ani:AnimationSet>
         </ani:Explicit.Animations>
         <media:UIElementExtensions.VisualFactory>

Microsoft.Toolkit.Uwp.UI.Animations/Xaml/Abstract/ShadowAnimation{TShadow,TValue,TKeyFrame}.cs → Microsoft.Toolkit.Uwp.UI.Animations/Xaml/Abstract/ShadowAnimation{TValue,TKeyFrame}.cs

@@ -13,24 +13,22 @@
 namespace Microsoft.Toolkit.Uwp.UI.Animations
 {
     /// <summary>
-    /// A custom animation targeting a property on an <see cref="AttachedShadowBase"/> instance.
+    /// A custom animation targeting a property on an <see cref="IAttachedShadow"/> instance.
     /// </summary>
-    /// <typeparam name="TShadow">The <see cref="FrameworkElement"/> containing the shadow to animate.</typeparam>
     /// <typeparam name="TValue">
     /// The type to use for the public <see cref="Animation{TValue,TKeyFrame}.To"/> and <see cref="Animation{TValue,TKeyFrame}.From"/>
     /// properties. This can differ from <typeparamref name="TKeyFrame"/> to facilitate XAML parsing.
     /// </typeparam>
     /// <typeparam name="TKeyFrame">The actual type of keyframe values in use.</typeparam>
-    public abstract class ShadowAnimation<TShadow, TValue, TKeyFrame> : Animation<TValue, TKeyFrame>, IAttachedTimeline
-        where TShadow : AttachedShadowBase
+    public abstract class ShadowAnimation<TValue, TKeyFrame> : Animation<TValue, TKeyFrame>, IAttachedTimeline
         where TKeyFrame : unmanaged
     {
         /// <summary>
-        /// Gets or sets the linked <typeparamref name="TShadow"/> instance to animate.
+        /// Gets or sets the linked <see cref="IAttachedShadow"/> instance to animate.
         /// </summary>
-        public TShadow? Target
+        public IAttachedShadow? Target
         {
-            get => (TShadow?)GetValue(TargetProperty);
+            get => (IAttachedShadow?)GetValue(TargetProperty);
             set => SetValue(TargetProperty, value);
         }
 
@@ -39,8 +37,8 @@ public TShadow? Target
         /// </summary>
         public static readonly DependencyProperty TargetProperty = DependencyProperty.Register(
             nameof(Target),
-            typeof(TShadow),
-            typeof(ShadowAnimation<TShadow, TValue, TKeyFrame>),
+            typeof(IAttachedShadow),
+            typeof(ShadowAnimation<TValue, TKeyFrame>),
             new PropertyMetadata(null));
 
         /// <inheritdoc/>
@@ -63,7 +61,7 @@ static AnimationBuilder ThrowArgumentNullException()
                 return ThrowArgumentNullException();
             }
 
-            if (Target is TShadow allShadows)
+            if (Target is IAttachedShadow allShadows)
             {
                 // in this case we'll animate all the shadows being used.
                 foreach (var context in allShadows.GetElementContextEnumerable()) //// TODO: Find better way!!!

Microsoft.Toolkit.Uwp.UI.Animations/Xaml/Shadows/BlurRadiusDropShadowAnimation.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Windows.UI.Composition;
+
+namespace Microsoft.Toolkit.Uwp.UI.Animations
+{
+    /// <summary>
+    /// A blur radius animation working on the composition layer.
+    /// </summary>
+    public sealed class BlurRadiusDropShadowAnimation : ShadowAnimation<double?, double>
+    {
+        /// <inheritdoc/>
+        protected override string ExplicitTarget => nameof(DropShadow.BlurRadius);
+
+        /// <inheritdoc/>
+        protected override (double?, double?) GetParsedValues()
+        {
+            return (To, From);
+        }
+    }
+}

Microsoft.Toolkit.Uwp.UI.Animations/Xaml/Shadows/ColorDropShadowAnimation.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Windows.UI;
+using Windows.UI.Composition;
+
+#pragma warning disable CS0419
+
+namespace Microsoft.Toolkit.Uwp.UI.Animations
+{
+    /// <summary>
+    /// A custom <see cref="Color"/> animation on a <see cref="DropShadow"/>.
+    /// </summary>
+    public sealed class ColorDropShadowAnimation : ShadowAnimation<Color?, Color>
+    {
+        /// <inheritdoc/>
+        protected override string ExplicitTarget => nameof(DropShadow.Color);
+
+        /// <inheritdoc/>
+        protected override (Color?, Color?) GetParsedValues()
+        {
+            return (To, From);
+        }
+    }
+}

Microsoft.Toolkit.Uwp.UI.Animations/Xaml/Shadows/OffsetDropShadowAnimation.cs

@@ -4,14 +4,13 @@
 
 using System.Numerics;
 using Windows.UI.Composition;
-using Windows.UI.Xaml;
 
 namespace Microsoft.Toolkit.Uwp.UI.Animations
 {
     /// <summary>
     /// An offset animation working on the composition layer.
     /// </summary>
-    public sealed class OffsetDropShadowAnimation : ShadowAnimation<AttachedShadowBase, string, Vector3>
+    public sealed class OffsetDropShadowAnimation : ShadowAnimation<string, Vector3>
     {
         /// <inheritdoc/>
         protected override string ExplicitTarget => nameof(DropShadow.Offset);

Microsoft.Toolkit.Uwp.UI.Animations/Xaml/Shadows/OpacityDropShadowAnimation.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Windows.UI.Composition;
+
+namespace Microsoft.Toolkit.Uwp.UI.Animations
+{
+    /// <summary>
+    /// An opacity animation working on the composition layer.
+    /// </summary>
+    public sealed class OpacityDropShadowAnimation : ShadowAnimation<double?, double>
+    {
+        /// <inheritdoc/>
+        protected override string ExplicitTarget => nameof(DropShadow.Opacity);
+
+        /// <inheritdoc/>
+        protected override (double?, double?) GetParsedValues()
+        {
+            return (To, From);
+        }
+    }
+}