ResizeWindow refactor 4

src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeKernel.cs

@@ -19,27 +19,27 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         /// Initializes a new instance of the <see cref="ResizeKernel"/> struct.
         /// </summary>
         [MethodImpl(InliningOptions.ShortMethod)]
-        internal ResizeKernel(int left, float* bufferPtr, int length)
+        internal ResizeKernel(int startIndex, float* bufferPtr, int length)
         {
-            this.Left = left;
+            this.StartIndex = startIndex;
             this.bufferPtr = bufferPtr;
             this.Length = length;
         }
 
         /// <summary>
-        /// Gets the left index for the destination row
+        /// Gets the start index for the destination row.
         /// </summary>
-        public int Left { get; }
+        public int StartIndex { get; }
 
         /// <summary>
-        /// Gets the the length of the kernel
+        /// Gets the the length of the kernel.
         /// </summary>
         public int Length { get; }
 
         /// <summary>
-        /// Gets the span representing the portion of the <see cref="ResizeKernelMap"/> that this window covers
+        /// Gets the span representing the portion of the <see cref="ResizeKernelMap"/> that this window covers.
         /// </summary>
-        /// <value>The <see cref="Span{T}"/>
+        /// <value>The <see cref="Span{T}"/>.
         /// </value>
         public Span<float> Values
         {
@@ -55,17 +55,22 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         [MethodImpl(InliningOptions.ShortMethod)]
         public Vector4 Convolve(Span<Vector4> rowSpan)
         {
-            ref float horizontalValues = ref Unsafe.AsRef<float>(this.bufferPtr);
-            int left = this.Left;
-            ref Vector4 vecPtr = ref Unsafe.Add(ref MemoryMarshal.GetReference(rowSpan), left);
+            ref Vector4 vecPtr = ref Unsafe.Add(ref MemoryMarshal.GetReference(rowSpan), this.StartIndex);
+
+            return this.ConvolveCore(ref vecPtr);
+        }
 
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public Vector4 ConvolveCore(ref Vector4 rowStartRef)
+        {
+            ref float horizontalValues = ref Unsafe.AsRef<float>(this.bufferPtr);
             // Destination color components
             Vector4 result = Vector4.Zero;
 
             for (int i = 0; i < this.Length; i++)
             {
                 float weight = Unsafe.Add(ref horizontalValues, i);
-                Vector4 v = Unsafe.Add(ref vecPtr, i);
+                Vector4 v = Unsafe.Add(ref rowStartRef, i);
                 result += v * weight;
             }
 
@@ -73,7 +78,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         }
 
         /// <summary>
-        /// Copy the contents of <see cref="ResizeKernel"/> altering <see cref="Left"/>
+        /// Copy the contents of <see cref="ResizeKernel"/> altering <see cref="StartIndex"/>
         /// to the value <paramref name="left"/>.
         /// </summary>
         internal ResizeKernel AlterLeftValue(int left)

src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor.cs

@@ -197,7 +197,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             int startY = this.TargetRectangle.Y;
             int startX = this.TargetRectangle.X;
 
-            var workingRect = Rectangle.Intersect(
+            var destWorkingRect = Rectangle.Intersect(
                 this.TargetRectangle,
                 new Rectangle(0, 0, width, height));
 
@@ -208,7 +208,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 float heightFactor = sourceRectangle.Height / (float)this.TargetRectangle.Height;
 
                 ParallelHelper.IterateRows(
-                    workingRect,
+                    destWorkingRect,
                     configuration,
                     rows =>
                     {
@@ -219,7 +219,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                                 source.GetPixelRowSpan((int)(((y - startY) * heightFactor) + sourceY));
                             Span<TPixel> targetRow = destination.GetPixelRowSpan(y);
 
-                            for (int x = workingRect.Left; x < workingRect.Right; x++)
+                            for (int x = destWorkingRect.Left; x < destWorkingRect.Right; x++)
                             {
                                 // X coordinates of source points
                                 targetRow[x] = sourceRow[(int)(((x - startX) * widthFactor) + sourceX)];
@@ -248,7 +248,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 this.horizontalKernelMap,
                 this.verticalKernelMap,
                 width,
-                workingRect,
+                destWorkingRect,
                 startX))
             using (IMemoryOwner<Vector4> tempBuffer = source.MemoryAllocator.Allocate<Vector4>(width))
             {
@@ -257,12 +257,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 // Now process the rows.
                 Span<Vector4> tempColSpan = tempBuffer.GetSpan();
 
-                for (int y = workingRect.Top; y < workingRect.Bottom; y++)
+                for (int y = destWorkingRect.Top; y < destWorkingRect.Bottom; y++)
                 {
                     // Ensure offsets are normalized for cropping and padding.
                     ResizeKernel kernel = this.verticalKernelMap.GetKernel(y - startY);
 
-                    if (kernel.Left + kernel.Length > resizeWindow.Bottom)
+                    if (kernel.StartIndex + kernel.Length > resizeWindow.Bottom)
                     {
                         resizeWindow.Slide();
                     }
@@ -271,10 +271,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
                     for (int x = 0; x < width; x++)
                     {
-                        Span<Vector4> firstPassColumn = resizeWindow.GetColumnSpan(x);
+                        Span<Vector4> firstPassColumn = resizeWindow.GetColumnSpan(x, kernel.StartIndex);
+                        ref Vector4 rowStartReference = ref MemoryMarshal.GetReference(firstPassColumn);
 
                         // Destination color components
-                        Unsafe.Add(ref tempRowBase, x) = kernel.Convolve(firstPassColumn);
+                        Unsafe.Add(ref tempRowBase, x) = kernel.ConvolveCore(ref rowStartReference);
                     }
 
                     Span<TPixel> targetRowSpan = destination.GetPixelRowSpan(y);

src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeWindow.cs

@@ -34,7 +34,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
         private readonly ResizeKernelMap verticalKernelMap;
 
-        private readonly Rectangle workingRectangle;
+        private readonly Rectangle destWorkingRect;
 
         private readonly int diameter;
 
@@ -45,7 +45,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             ResizeKernelMap horizontalKernelMap,
             ResizeKernelMap verticalKernelMap,
             int destWidth,
-            Rectangle workingRectangle,
+            Rectangle destWorkingRect,
             int startX)
         {
             this.configuration = configuration;
@@ -54,7 +54,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             this.conversionModifiers = conversionModifiers;
             this.horizontalKernelMap = horizontalKernelMap;
             this.verticalKernelMap = verticalKernelMap;
-            this.workingRectangle = workingRectangle;
+            this.destWorkingRect = destWorkingRect;
             this.startX = startX;
 
             this.diameter = verticalKernelMap.MaxDiameter;
@@ -65,9 +65,9 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 AllocationOptions.Clean);
             this.tempRowBuffer = configuration.MemoryAllocator.Allocate<Vector4>(this.sourceRectangle.Width);
 
-            this.Top = this.sourceRectangle.Top;
+            this.Top = 0;
 
-            this.Bottom = this.sourceRectangle.Bottom;
+            this.Bottom = this.sourceRectangle.Height;
         }
 
         public int Bottom { get; private set; }
@@ -80,15 +80,25 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public Span<Vector4> GetColumnSpan(int x)
+        public Span<Vector4> GetColumnSpan(int x, int startY)
         {
-            return this.buffer.GetRowSpan(x);
+            return this.buffer.GetRowSpan(x).Slice(startY);
         }
 
         public void Initialize()
+        {
+            this.Initialize(0, this.sourceRectangle.Height);
+        }
+
+        public void Slide()
+        {
+            throw new InvalidOperationException("Shouldn't happen yet!");
+        }
+
+        private void Initialize(int top, int bottom)
         {
             Span<Vector4> tempRowSpan = this.tempRowBuffer.GetSpan();
-            for (int y = 0; y < this.sourceRectangle.Height; y++)
+            for (int y = top; y < bottom; y++)
             {
                 Span<TPixel> sourceRow = this.source.GetRowSpan(y);
 
@@ -100,17 +110,12 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
                 ref Vector4 firstPassBaseRef = ref this.buffer.Span[y];
 
-                for (int x = this.workingRectangle.Left; x < this.workingRectangle.Right; x++)
+                for (int x = this.destWorkingRect.Left; x < this.destWorkingRect.Right; x++)
                 {
                     ResizeKernel kernel = this.horizontalKernelMap.GetKernel(x - this.startX);
                     Unsafe.Add(ref firstPassBaseRef, x * this.sourceRectangle.Height) = kernel.Convolve(tempRowSpan);
                 }
             }
         }
-
-        public void Slide()
-        {
-            throw new InvalidOperationException("Shouldn't happen yet!");
-        }
     }
 }

tests/ImageSharp.Tests/Processing/Processors/Transforms/ResizeKernelMapTests.ReferenceKernelMap.cs

@@ -104,7 +104,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
 
             public static implicit operator ReferenceKernel(ResizeKernel orig)
             {
-                return new ReferenceKernel(orig.Left, orig.Values.ToArray());
+                return new ReferenceKernel(orig.StartIndex, orig.Values.ToArray());
             }
         }
     }

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

@@ -151,8 +151,8 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
                     referenceKernel.Length == kernel.Length,
                     $"referenceKernel.Length != kernel.Length: {referenceKernel.Length} != {kernel.Length}");
                 Assert.True(
-                    referenceKernel.Left == kernel.Left,
-                    $"referenceKernel.Left != kernel.Left: {referenceKernel.Left} != {kernel.Left}");
+                    referenceKernel.Left == kernel.StartIndex,
+                    $"referenceKernel.Left != kernel.Left: {referenceKernel.Left} != {kernel.StartIndex}");
                 float[] expectedValues = referenceKernel.Values;
                 Span<float> actualValues = kernel.Values;