Cache WebGPU support and gate drawing backend

Author: JimBobSquarePants

src/ImageSharp.Drawing.WebGPU/WebGPUDrawingBackend.cs

@@ -49,6 +49,7 @@ public sealed unsafe partial class WebGPUDrawingBackend : IDrawingBackend, IDisp
     private const int CallbackTimeoutMilliseconds = 10_000;
 
     private readonly DefaultDrawingBackend fallbackBackend;
+    private static bool? isSupported;
     private bool isDisposed;
 
     private static readonly Dictionary<Type, CompositePixelRegistration> CompositePixelHandlers = CreateCompositePixelHandlers();
@@ -75,24 +76,6 @@ private enum PreparedBrushType : uint
         Recolor = 8,
     }
 
-    /// <summary>
-    /// Gets a value indicating whether WebGPU is available on the current system.
-    /// This probes the runtime by attempting to acquire an adapter and device.
-    /// </summary>
-    /// <returns><see langword="true"/> when WebGPU is functional; otherwise <see langword="false"/>.</returns>
-    public static bool IsSupported()
-    {
-        try
-        {
-            using WebGPURuntime.Lease lease = WebGPURuntime.Acquire();
-            return WebGPURuntime.TryGetOrCreateDevice(out _, out _, out _);
-        }
-        catch
-        {
-            return false;
-        }
-    }
-
     /// <summary>
     /// Gets the testing-only diagnostic counter for total coverage preparation requests.
     /// </summary>
@@ -154,6 +137,26 @@ public static bool IsSupported()
     /// </summary>
     internal int TestingComputePathBatchCount { get; private set; }
 
+    /// <summary>
+    /// Gets a value indicating whether WebGPU is available on the current system.
+    /// This probes the runtime by attempting to acquire an adapter and device.
+    /// The result is cached after the first probe.
+    /// </summary>
+    public bool IsSupported => isSupported ??= ProbeSupport();
+
+    private static bool ProbeSupport()
+    {
+        try
+        {
+            using WebGPURuntime.Lease lease = WebGPURuntime.Acquire();
+            return WebGPURuntime.TryGetOrCreateDevice(out _, out _, out _);
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
     /// <inheritdoc />
     public void FlushCompositions<TPixel>(
         Configuration configuration,
@@ -324,7 +327,7 @@ public void ReleaseFrameResources<TPixel>(
         ICanvasFrame<TPixel> target)
         where TPixel : unmanaged, IPixel<TPixel>
     {
-        nint targetIdentity = (nint)RuntimeHelpers.GetHashCode(target);
+        nint targetIdentity = RuntimeHelpers.GetHashCode(target);
         WebGPUFlushContext.ReleaseCpuTargetEntries(targetIdentity);
     }
 

src/ImageSharp.Drawing/Processing/Backends/IDrawingBackend.cs

@@ -10,6 +10,11 @@ namespace SixLabors.ImageSharp.Drawing.Processing.Backends;
 /// </summary>
 public interface IDrawingBackend
 {
+    /// <summary>
+    /// Gets a value indicating whether this backend is available on the current system.
+    /// </summary>
+    public bool IsSupported => true;
+
     /// <summary>
     /// Flushes queued composition operations for the target.
     /// </summary>

src/ImageSharp.Drawing/Processing/RasterizerDefaultsExtensions.cs

@@ -43,7 +43,8 @@ public static void SetDrawingBackend(this Configuration configuration, IDrawingB
     internal static IDrawingBackend GetDrawingBackend(this IImageProcessingContext context)
     {
         if (context.Properties.TryGetValue(typeof(IDrawingBackend), out object? backend) &&
-            backend is IDrawingBackend configured)
+            backend is IDrawingBackend configured &&
+            configured.IsSupported)
         {
             return configured;
         }
@@ -59,7 +60,8 @@ internal static IDrawingBackend GetDrawingBackend(this IImageProcessingContext c
     internal static IDrawingBackend GetDrawingBackend(this Configuration configuration)
     {
         if (configuration.Properties.TryGetValue(typeof(IDrawingBackend), out object? backend) &&
-            backend is IDrawingBackend configured)
+            backend is IDrawingBackend configured &&
+            configured.IsSupported)
         {
             return configured;
         }

…Utilities/Attributes/WebGPUAttributes.cs …lities/Attributes/WebGPUFactAttribute.cstests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/WebGPUAttributes.cs renamed to tests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/WebGPUFactAttribute.cs tests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/WebGPUAttributes.cs renamed to tests/ImageSharp.Drawing.Tests/TestUtilities/Attributes/WebGPUFactAttribute.cs

@@ -12,7 +12,8 @@ public class WebGPUFactAttribute : FactAttribute
 {
     public WebGPUFactAttribute()
     {
-        if (!WebGPUDrawingBackend.IsSupported())
+        using WebGPUDrawingBackend backend = new();
+        if (!backend.IsSupported)
         {
             this.Skip = "WebGPU is not available on this system.";
         }
@@ -26,7 +27,8 @@ public class WebGPUTheoryAttribute : TheoryAttribute
 {
     public WebGPUTheoryAttribute()
     {
-        if (!WebGPUDrawingBackend.IsSupported())
+        using WebGPUDrawingBackend backend = new();
+        if (!backend.IsSupported)
         {
             this.Skip = "WebGPU is not available on this system.";
         }