Fix benchmark resize handling

Author: JimBobSquarePants

samples/DrawingBackendBenchmark/CpuBenchmarkBackend.cs

@@ -16,6 +16,8 @@ internal sealed class CpuBenchmarkBackend : IBenchmarkBackend
 {
     private readonly Configuration configuration;
     private Image<Bgra32>? image;
+    private int cachedWidth;
+    private int cachedHeight;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="CpuBenchmarkBackend"/> class.
@@ -63,12 +65,15 @@ public void Dispose()
     /// <returns>The cached image.</returns>
     private Image<Bgra32> EnsureImage(int width, int height)
     {
-        if (this.image is not null)
+        if (this.image is not null && this.cachedWidth == width && this.cachedHeight == height)
         {
             return this.image;
         }
 
+        this.image?.Dispose();
         this.image = new Image<Bgra32>(width, height);
+        this.cachedWidth = width;
+        this.cachedHeight = height;
         return this.image;
     }
 }

samples/DrawingBackendBenchmark/WebGpuBenchmarkBackend.cs

@@ -16,6 +16,8 @@ namespace DrawingBackendBenchmark;
 internal sealed class WebGpuBenchmarkBackend : IBenchmarkBackend
 {
     private WebGPURenderTarget<Bgra32>? renderTarget;
+    private int cachedWidth;
+    private int cachedHeight;
 
     private WebGpuBenchmarkBackend()
     {
@@ -88,12 +90,15 @@ public void Dispose()
 
     private WebGPURenderTarget<Bgra32> EnsureRenderTarget(int width, int height)
     {
-        if (this.renderTarget is not null)
+        if (this.renderTarget is not null && this.cachedWidth == width && this.cachedHeight == height)
         {
             return this.renderTarget;
         }
 
+        this.renderTarget?.Dispose();
         this.renderTarget = new WebGPURenderTarget<Bgra32>(width, height);
+        this.cachedWidth = width;
+        this.cachedHeight = height;
         return this.renderTarget;
     }
 }

tests/ImageSharp.Drawing.Tests/Processing/Backends/WebGPUDrawingBackendTests.cs

@@ -870,8 +870,7 @@ private static void DebugSaveBackendPair<TPixel>(
         TestImageProvider<TPixel> provider,
         string testName,
         Image<TPixel> defaultImage,
-        Image<TPixel> nativeSurfaceImage,
-        float tolerantPercentage = 0.0003F)
+        Image<TPixel> nativeSurfaceImage)
         where TPixel : unmanaged, IPixel<TPixel>
     {
         defaultImage.DebugSave(
@@ -1508,7 +1507,7 @@ public void FillPath_WithLinearGradientBrush_MatchesDefaultOutput<TPixel>(TestIm
             nativeSurfaceInitialImage);
 
         // MacOS on CI has some outliers with this test, so using a slightly higher tolerance here to avoid noise.
-        DebugSaveBackendPair(provider, "FillPath_LinearGradient", defaultImage, nativeSurfaceImage, tolerantPercentage: 0.0007F);
+        DebugSaveBackendPair(provider, "FillPath_LinearGradient", defaultImage, nativeSurfaceImage);
         AssertBackendPairSimilarity(defaultImage, nativeSurfaceImage, 0.03F);
         AssertBackendPairReferenceOutputs(
             provider,
@@ -1759,8 +1758,7 @@ public void FillPath_WithSweepGradientBrush_PartialArc_MatchesDefaultOutput<TPix
             provider,
             "FillPath_SweepGradient_PartialArc",
             defaultImage,
-            nativeSurfaceImage,
-            tolerantPercentage: 0.0280F);
+            nativeSurfaceImage);
         AssertBackendPairSimilarity(defaultImage, nativeSurfaceImage, 0.0280F);
         AssertBackendPairReferenceOutputs(
             provider,