Remove WebGPUTextureTransfer and use Readback APIs

Author: JimBobSquarePants

src/ImageSharp.Drawing.WebGPU/WebGPURenderTargetAllocation.cs

@@ -7,7 +7,7 @@
 namespace SixLabors.ImageSharp.Drawing.Processing.Backends;
 
 /// <summary>
-/// Shared WebGPU render-target allocation helpers used by the public target API and internal tests.
+/// Shared WebGPU render-target allocation helpers used by the public target API.
 /// </summary>
 internal static unsafe class WebGPURenderTargetAllocation
 {

src/ImageSharp.Drawing.WebGPU/WebGPURenderTarget{TPixel}.cs

@@ -211,12 +211,11 @@ public void ReadbackInto(Image<TPixel> destination)
                 nameof(destination));
         }
 
-        Buffer2DRegion<TPixel> region = new(destination.Frames.RootFrame.PixelBuffer, destination.Bounds);
         if (!this.Graphics.Backend.TryReadRegion(
                 this.Graphics.Configuration,
                 this.NativeFrame,
                 new Rectangle(0, 0, this.Width, this.Height),
-                region,
+                new Buffer2DRegion<TPixel>(destination.Frames.RootFrame.PixelBuffer),
                 out string? error))
         {
             if (error is null)

src/ImageSharp.Drawing.WebGPU/WebGPUTextureTransfer.cs

@@ -191,7 +191,7 @@ internal static void VerifyOutput()
             bench.skSurface,
             bench.sdBitmap,
             bench.image,
-            bench.webGpuTarget.TextureHandle);
+            bench.webGpuTarget);
 
         bench.Cleanup();
     }

tests/ImageSharp.Drawing.Benchmarks/Drawing/FillParis.cs

@@ -218,7 +218,7 @@ public static void VerifyOutput(int dimensions = 1000)
             bench.skSurface,
             bench.sdBitmap,
             bench.image,
-            bench.webGpuTarget.TextureHandle);
+            bench.webGpuTarget);
 
         bench.Cleanup();
     }
@@ -278,15 +278,8 @@ public static void VerifyTransformBaked(int width, int height, float zoom, float
         System.IO.Directory.CreateDirectory(dir);
         image.Save(System.IO.Path.Combine(dir, tag + "-imagesharp.png"));
 
-        if (WebGPUTextureTransfer.TryReadTexture(webGpuTarget.TextureHandle, width, height, out Image<Rgba32> gpuImage, out string readError))
-        {
-            gpuImage.SaveAsPng(System.IO.Path.Combine(dir, tag + "-webgpu.png"));
-            gpuImage.Dispose();
-        }
-        else
-        {
-            Console.WriteLine($"WebGPU readback failed: {readError}");
-        }
+        using Image<Rgba32> gpuImage = webGpuTarget.Readback();
+        gpuImage.SaveAsPng(System.IO.Path.Combine(dir, tag + "-webgpu.png"));
 
         Console.WriteLine($"Output saved to: {dir}");
 
@@ -370,7 +363,7 @@ public static void VerifyTransform(int width, int height, float zoom, float panX
         PrintWebGpuDiagnostics(printer);
 
         string tag = $"tiger-xform-{width}x{height}-z{zoom:0.##}-p{panX:0.##}_{panY:0.##}";
-        SvgBenchmarkHelper.VerifyOutput(tag, width, height, sk, sdBitmap, image, webGpuTarget.TextureHandle);
+        SvgBenchmarkHelper.VerifyOutput(tag, width, height, sk, sdBitmap, image, webGpuTarget);
 
         foreach ((SKPath path, SKPaint fill, SKPaint stroke) in skElements)
         {