Removed legacy SupportsCompositionVisualSurface.

Fixes #4364

Author: azchohfi

CommunityToolkit.WinUI.UI.Media/Shadows/AttachedCardShadow.cs

@@ -48,9 +48,6 @@ public double CornerRadius
             set => SetValue(CornerRadiusProperty, value);
         }
 
-        /// <inheritdoc/>
-        public override bool IsSupported => SupportsCompositionVisualSurface;
-
         /// <inheritdoc/>
         protected internal override bool SupportsOnSizeChangedEvent => true;
 
@@ -76,11 +73,6 @@ protected override void OnPropertyChanged(AttachedShadowElementContext context,
         /// <inheritdoc/>
         protected override CompositionBrush GetShadowMask(AttachedShadowElementContext context)
         {
-            if (!SupportsCompositionVisualSurface)
-            {
-                return null;
-            }
-
             // Create rounded rectangle geometry and add it to a shape
             var geometry = context.GetResource(RoundedRectangleGeometryResourceKey) ?? context.AddResource(
                 RoundedRectangleGeometryResourceKey,

CommunityToolkit.WinUI.UI/Shadows/AttachedDropShadow.cs

@@ -22,9 +22,6 @@ public sealed class AttachedDropShadow : AttachedShadowBase
     {
         private const float MaxBlurRadius = 72;
 
-        /// <inheritdoc/>
-        public override bool IsSupported => true;
-
         /// <inheritdoc/>
         protected internal override bool SupportsOnSizeChangedEvent => true;
 
@@ -276,7 +273,7 @@ protected override CompositionBrush GetShadowMask(AttachedShadowElementContext c
 
                 // If we don't have a mask and have specified rounded corners, we'll generate a simple quick mask.
                 // This is the same code from link:AttachedCardShadow.cs:GetShadowMask
-                if (mask == null && SupportsCompositionVisualSurface && CornerRadius > 0)
+                if (mask == null && CornerRadius > 0)
                 {
                     // Create rounded rectangle geometry and add it to a shape
                     var geometry = context.GetResource(RoundedRectangleGeometryResourceKey) ?? context.AddResource(

CommunityToolkit.WinUI.UI/Shadows/AttachedShadowBase.cs

@@ -20,11 +20,6 @@ namespace CommunityToolkit.WinUI.UI
     /// </summary>
     public abstract class AttachedShadowBase : DependencyObject, IAttachedShadow
     {
-        /// <summary>
-        /// Gets a value indicating whether or not Composition's VisualSurface is supported.
-        /// </summary>
-        protected static readonly bool SupportsCompositionVisualSurface = ApiInformation.IsTypePresent(typeof(CompositionVisualSurface).FullName);
-
         /// <summary>
         /// The <see cref="DependencyProperty"/> for <see cref="BlurRadius"/>.
         /// </summary>
@@ -53,11 +48,6 @@ public abstract class AttachedShadowBase : DependencyObject, IAttachedShadow
         public static readonly DependencyProperty OpacityProperty =
             DependencyProperty.Register(nameof(Opacity), typeof(double), typeof(AttachedShadowBase), new PropertyMetadata(1d, OnDependencyPropertyChanged));
 
-        /// <summary>
-        /// Gets a value indicating whether or not this <see cref="AttachedShadowBase"/> implementation is supported on the current platform.
-        /// </summary>
-        public abstract bool IsSupported { get; }
-
         /// <summary>
         /// Gets or sets the collection of <see cref="AttachedShadowElementContext"/> for each element this <see cref="AttachedShadowBase"/> is connected to.
         /// </summary>
@@ -106,11 +96,6 @@ protected static void OnDependencyPropertyChanged(object sender, DependencyPrope
 
         internal void ConnectElement(FrameworkElement element)
         {
-            if (!IsSupported)
-            {
-                return;
-            }
-
             ShadowElementContextTable = ShadowElementContextTable ?? new ConditionalWeakTable<FrameworkElement, AttachedShadowElementContext>();
             if (ShadowElementContextTable.TryGetValue(element, out var context))
             {