Revert "Merge pull request #1108 from SixLabors/sp/single-row-paralle…

…l-value-delegate"

This reverts commit 1835475, reversing
changes made to dd7bd7b.

src/ImageSharp/Advanced/ParallelRowIterator.cs

@@ -19,32 +19,32 @@ namespace SixLabors.ImageSharp.Advanced
     public static class ParallelRowIterator
     {
         /// <summary>
-        /// Iterate through the rows of a rectangle in optimized batches.
+        /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s.
         /// </summary>
         /// <typeparam name="T">The type of row action to perform.</typeparam>
         /// <param name="rectangle">The <see cref="Rectangle"/>.</param>
         /// <param name="configuration">The <see cref="Configuration"/> to get the parallel settings from.</param>
-        /// <param name="body">The method body defining the iteration logic on a single row.</param>
+        /// <param name="body">The method body defining the iteration logic on a single <see cref="RowInterval"/>.</param>
         [MethodImpl(InliningOptions.ShortMethod)]
         public static void IterateRows<T>(Rectangle rectangle, Configuration configuration, in T body)
-            where T : struct, IRowAction
+            where T : struct, IRowIntervalAction
         {
             var parallelSettings = ParallelExecutionSettings.FromConfiguration(configuration);
             IterateRows(rectangle, in parallelSettings, in body);
         }
 
         /// <summary>
-        /// Iterate through the rows of a rectangle in optimized batches.
+        /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s.
         /// </summary>
         /// <typeparam name="T">The type of row action to perform.</typeparam>
         /// <param name="rectangle">The <see cref="Rectangle"/>.</param>
         /// <param name="parallelSettings">The <see cref="ParallelExecutionSettings"/>.</param>
-        /// <param name="body">The method body defining the iteration logic on a single row.</param>
+        /// <param name="body">The method body defining the iteration logic on a single <see cref="RowInterval"/>.</param>
         public static void IterateRows<T>(
             Rectangle rectangle,
             in ParallelExecutionSettings parallelSettings,
             in T body)
-            where T : struct, IRowAction
+            where T : struct, IRowIntervalAction
         {
             ValidateRectangle(rectangle);
 
@@ -59,17 +59,15 @@ public static void IterateRows<T>(
             // Avoid TPL overhead in this trivial case:
             if (numOfSteps == 1)
             {
-                for (int y = top; y < bottom; y++)
-                {
-                    Unsafe.AsRef(body).Invoke(y);
-                }
-
+                var rows = new RowInterval(top, bottom);
+                Unsafe.AsRef(body).Invoke(in rows);
                 return;
             }
 
             int verticalStep = DivideCeil(rectangle.Height, numOfSteps);
             var parallelOptions = new ParallelOptions { MaxDegreeOfParallelism = numOfSteps };
-            var rowAction = new WrappingRowAction<T>(top, bottom, verticalStep, in body);
+            var rowInfo = new WrappingRowIntervalInfo(top, bottom, verticalStep);
+            var rowAction = new WrappingRowIntervalAction<T>(in rowInfo, in body);
 
             Parallel.For(
                 0,
@@ -88,7 +86,7 @@ public static void IterateRows<T>(
         /// <param name="configuration">The <see cref="Configuration"/> to get the parallel settings from.</param>
         /// <param name="body">The method body defining the iteration logic on a single <see cref="RowInterval"/>.</param>
         public static void IterateRows<T, TBuffer>(Rectangle rectangle, Configuration configuration, in T body)
-            where T : struct, IRowAction<TBuffer>
+            where T : struct, IRowIntervalAction<TBuffer>
             where TBuffer : unmanaged
         {
             var parallelSettings = ParallelExecutionSettings.FromConfiguration(configuration);
@@ -103,7 +101,7 @@ internal static void IterateRows<T, TBuffer>(
             Rectangle rectangle,
             in ParallelExecutionSettings parallelSettings,
             in T body)
-            where T : struct, IRowAction<TBuffer>
+            where T : struct, IRowIntervalAction<TBuffer>
             where TBuffer : unmanaged
         {
             ValidateRectangle(rectangle);
@@ -120,22 +118,19 @@ internal static void IterateRows<T, TBuffer>(
             // Avoid TPL overhead in this trivial case:
             if (numOfSteps == 1)
             {
+                var rows = new RowInterval(top, bottom);
                 using (IMemoryOwner<TBuffer> buffer = allocator.Allocate<TBuffer>(width))
                 {
-                    Span<TBuffer> span = buffer.Memory.Span;
-
-                    for (int y = top; y < bottom; y++)
-                    {
-                        Unsafe.AsRef(body).Invoke(y, span);
-                    }
+                    Unsafe.AsRef(body).Invoke(rows, buffer.Memory);
                 }
 
                 return;
             }
 
             int verticalStep = DivideCeil(height, numOfSteps);
             var parallelOptions = new ParallelOptions { MaxDegreeOfParallelism = numOfSteps };
-            var rowAction = new WrappingRowAction<T, TBuffer>(top, bottom, verticalStep, width, allocator, in body);
+            var rowInfo = new WrappingRowIntervalInfo(top, bottom, verticalStep, width);
+            var rowAction = new WrappingRowIntervalBufferAction<T, TBuffer>(in rowInfo, allocator, in body);
 
             Parallel.For(
                 0,

src/ImageSharp/ImageFrame{TPixel}.cs

@@ -263,7 +263,7 @@ internal ImageFrame<TPixel2> CloneAs<TPixel2>(Configuration configuration)
             ParallelRowIterator.IterateRows(
                 this.Bounds(),
                 configuration,
-                new RowAction<TPixel2>(this, target, configuration));
+                new RowIntervalAction<TPixel2>(this, target, configuration));
 
             return target;
         }
@@ -289,15 +289,15 @@ internal void Clear(TPixel value)
         /// <summary>
         /// A <see langword="struct"/> implementing the clone logic for <see cref="ImageFrame{TPixel}"/>.
         /// </summary>
-        private readonly struct RowAction<TPixel2> : IRowAction
+        private readonly struct RowIntervalAction<TPixel2> : IRowIntervalAction
             where TPixel2 : struct, IPixel<TPixel2>
         {
             private readonly ImageFrame<TPixel> source;
             private readonly ImageFrame<TPixel2> target;
             private readonly Configuration configuration;
 
             [MethodImpl(InliningOptions.ShortMethod)]
-            public RowAction(
+            public RowIntervalAction(
                 ImageFrame<TPixel> source,
                 ImageFrame<TPixel2> target,
                 Configuration configuration)
@@ -309,11 +309,14 @@ public RowAction(
 
             /// <inheritdoc/>
             [MethodImpl(InliningOptions.ShortMethod)]
-            public void Invoke(int y)
+            public void Invoke(in RowInterval rows)
             {
-                Span<TPixel> sourceRow = this.source.GetPixelRowSpan(y);
-                Span<TPixel2> targetRow = this.target.GetPixelRowSpan(y);
-                PixelOperations<TPixel>.Instance.To(this.configuration, sourceRow, targetRow);
+                for (int y = rows.Min; y < rows.Max; y++)
+                {
+                    Span<TPixel> sourceRow = this.source.GetPixelRowSpan(y);
+                    Span<TPixel2> targetRow = this.target.GetPixelRowSpan(y);
+                    PixelOperations<TPixel>.Instance.To(this.configuration, sourceRow, targetRow);
+                }
             }
         }
     }

src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor{TPixel}.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Processing.Processors.Binarization
@@ -53,13 +54,13 @@ protected override void OnFrameApply(ImageFrame<TPixel> source)
             ParallelRowIterator.IterateRows(
                 workingRect,
                 configuration,
-                new RowAction(source, upper, lower, threshold, startX, endX, isAlphaOnly));
+                new RowIntervalAction(source, upper, lower, threshold, startX, endX, isAlphaOnly));
         }
 
         /// <summary>
         /// A <see langword="struct"/> implementing the clone logic for <see cref="BinaryThresholdProcessor{TPixel}"/>.
         /// </summary>
-        private readonly struct RowAction : IRowAction
+        private readonly struct RowIntervalAction : IRowIntervalAction
         {
             private readonly ImageFrame<TPixel> source;
             private readonly TPixel upper;
@@ -70,7 +71,7 @@ protected override void OnFrameApply(ImageFrame<TPixel> source)
             private readonly bool isAlphaOnly;
 
             [MethodImpl(InliningOptions.ShortMethod)]
-            public RowAction(
+            public RowIntervalAction(
                 ImageFrame<TPixel> source,
                 TPixel upper,
                 TPixel lower,
@@ -90,20 +91,22 @@ public RowAction(
 
             /// <inheritdoc/>
             [MethodImpl(InliningOptions.ShortMethod)]
-            public void Invoke(int y)
+            public void Invoke(in RowInterval rows)
             {
                 Rgba32 rgba = default;
-
-                Span<TPixel> row = this.source.GetPixelRowSpan(y);
-
-                for (int x = this.startX; x < this.endX; x++)
+                for (int y = rows.Min; y < rows.Max; y++)
                 {
-                    ref TPixel color = ref row[x];
-                    color.ToRgba32(ref rgba);
+                    Span<TPixel> row = this.source.GetPixelRowSpan(y);
+
+                    for (int x = this.startX; x < this.endX; x++)
+                    {
+                        ref TPixel color = ref row[x];
+                        color.ToRgba32(ref rgba);
 
-                    // Convert to grayscale using ITU-R Recommendation BT.709 if required
-                    byte luminance = this.isAlphaOnly ? rgba.A : ImageMaths.Get8BitBT709Luminance(rgba.R, rgba.G, rgba.B);
-                    color = luminance >= this.threshold ? this.upper : this.lower;
+                        // Convert to grayscale using ITU-R Recommendation BT.709 if required
+                        byte luminance = this.isAlphaOnly ? rgba.A : ImageMaths.Get8BitBT709Luminance(rgba.R, rgba.G, rgba.B);
+                        color = luminance >= this.threshold ? this.upper : this.lower;
+                    }
                 }
             }
         }