ParallelHelper -> CropProcessor, additional FlipProcessor test

src/ImageSharp/Common/ParallelUtils/ParallelExecutionSettings.cs

@@ -12,7 +12,15 @@ namespace SixLabors.ImageSharp.ParallelUtils
     /// </summary>
     internal struct ParallelExecutionSettings
     {
-        public ParallelExecutionSettings(int maxDegreeOfParallelism, int minimumPixelsProcessedPerTask, MemoryAllocator memoryAllocator)
+        /// <summary>
+        /// Default value for <see cref="MinimumPixelsProcessedPerTask"/>.
+        /// </summary>
+        public const int DefaultMinimumPixelsProcessedPerTask = 2048;
+
+        public ParallelExecutionSettings(
+            int maxDegreeOfParallelism,
+            int minimumPixelsProcessedPerTask,
+            MemoryAllocator memoryAllocator)
         {
             this.MaxDegreeOfParallelism = maxDegreeOfParallelism;
             this.MinimumPixelsProcessedPerTask = minimumPixelsProcessedPerTask;
@@ -20,7 +28,7 @@ namespace SixLabors.ImageSharp.ParallelUtils
         }
 
         public ParallelExecutionSettings(int maxDegreeOfParallelism, MemoryAllocator memoryAllocator)
-            : this(maxDegreeOfParallelism, 2048, memoryAllocator)
+            : this(maxDegreeOfParallelism, DefaultMinimumPixelsProcessedPerTask, memoryAllocator)
         {
         }
 
@@ -37,5 +45,13 @@ namespace SixLabors.ImageSharp.ParallelUtils
         /// Initialized with 2048 by default, the optimum value is operation specific.
         /// </summary>
         public int MinimumPixelsProcessedPerTask { get; }
+
+        public ParallelExecutionSettings MultiplyMinimumPixelsPerTask(int multiplier)
+        {
+            return new ParallelExecutionSettings(
+                this.MaxDegreeOfParallelism,
+                this.MinimumPixelsProcessedPerTask * multiplier,
+                this.MemoryAllocator);
+        }
     }
 }

src/ImageSharp/Processing/Processors/Transforms/CropProcessor.cs

@@ -4,8 +4,8 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Threading.Tasks;
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
@@ -53,21 +53,23 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 return;
             }
 
-            int minY = Math.Max(this.CropRectangle.Y, sourceRectangle.Y);
-            int maxY = Math.Min(this.CropRectangle.Bottom, sourceRectangle.Bottom);
-            int minX = Math.Max(this.CropRectangle.X, sourceRectangle.X);
-            int maxX = Math.Min(this.CropRectangle.Right, sourceRectangle.Right);
+            var rect = Rectangle.Intersect(this.CropRectangle, sourceRectangle);
 
-            ParallelFor.WithConfiguration(
-                minY,
-                maxY,
-                configuration,
-                y =>
-                {
-                    Span<TPixel> sourceRow = source.GetPixelRowSpan(y).Slice(minX);
-                    Span<TPixel> targetRow = destination.GetPixelRowSpan(y - minY);
-                    sourceRow.Slice(0, maxX - minX).CopyTo(targetRow);
-                });
+            // Copying is cheap, we should process more pixels per task:
+            ParallelExecutionSettings parallelSettings = configuration.GetParallelSettings().MultiplyMinimumPixelsPerTask(4);
+
+            ParallelHelper.IterateRows(
+                rect,
+                parallelSettings,
+                rows =>
+                    {
+                        for (int y = rows.Min; y < rows.Max; y++)
+                        {
+                            Span<TPixel> sourceRow = source.GetPixelRowSpan(y).Slice(rect.Left);
+                            Span<TPixel> targetRow = destination.GetPixelRowSpan(y - rect.Top);
+                            sourceRow.Slice(0, rect.Width).CopyTo(targetRow);
+                        }
+                    });
         }
     }
 }

src/ImageSharp/Processing/Processors/Transforms/FlipProcessor.cs

@@ -57,8 +57,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             int height = source.Height;
             int halfHeight = (int)Math.Ceiling(source.Height * .5F);
 
+          
             using (Buffer2D<TPixel> targetPixels = configuration.MemoryAllocator.Allocate2D<TPixel>(source.Size()))
             {
+
+
                 ParallelFor.WithConfiguration(
                     0,
                     halfHeight,

tests/ImageSharp.Tests/Processing/Processors/Transforms/FlipTests.cs

@@ -5,23 +5,24 @@ using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 
 using Xunit;
+
 // ReSharper disable InconsistentNaming
 
 namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
 {
-    using SixLabors.ImageSharp.Processing;
-
+    [GroupOutput("Transforms")]
     public class FlipTests
     {
-        public static readonly TheoryData<FlipMode> FlipValues
-            = new TheoryData<FlipMode>
-        {
-            { FlipMode.None },
-            { FlipMode.Vertical },
-            { FlipMode.Horizontal },
-        };
+        public static readonly TheoryData<FlipMode> FlipValues =
+            new TheoryData<FlipMode>
+                {
+                    FlipMode.None,
+                    FlipMode.Vertical,
+                    FlipMode.Horizontal,
+                };
 
         [Theory]
+        [WithTestPatternImages(nameof(FlipValues), 20, 37, PixelTypes.Rgba32)]
         [WithTestPatternImages(nameof(FlipValues), 53, 37, PixelTypes.Rgba32)]
         [WithTestPatternImages(nameof(FlipValues), 17, 32, PixelTypes.Rgba32)]
         public void Flip<TPixel>(TestImageProvider<TPixel> provider, FlipMode flipMode)

tests/Images/External

@@ -1 +1 @@
-Subproject commit 2841a79efd68d47c6552ce857869eb0d80f8de75
+Subproject commit c1e14c0e431066c57585f255d3feb8d3a1860d50