From ae72b03e9a8bab2ae401626aa581ac4eeb81f945 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Mon, 16 Apr 2018 20:32:25 +1000
Subject: [PATCH] Spectral tests are now 100% accurate.

Error is now when collating blocks for color transform.
---
 .../Jpeg/Common/Decoder/ComponentUtils.cs        | 16 ----------------
 .../Jpeg/Common/Decoder/IJpegComponent.cs        |  8 ++++++++
 .../Components/Decoder/OrigComponent.cs          |  7 +++++++
 .../PdfJsPort/Components/PdfJsFrameComponent.cs  | 13 ++++++++++---
 .../Jpg/Utils/LibJpegTools.ComponentData.cs      |  5 +++++
 5 files changed, 30 insertions(+), 19 deletions(-)
 delete mode 100644 src/ImageSharp/Formats/Jpeg/Common/Decoder/ComponentUtils.cs

diff --git a/src/ImageSharp/Formats/Jpeg/Common/Decoder/ComponentUtils.cs b/src/ImageSharp/Formats/Jpeg/Common/Decoder/ComponentUtils.cs
deleted file mode 100644
index da97f9e2a..000000000
--- a/src/ImageSharp/Formats/Jpeg/Common/Decoder/ComponentUtils.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
-{
-    /// <summary>
-    /// Various utilities for <see cref="IJpegComponent"/>.
-    /// </summary>
-    internal static class ComponentUtils
-    {
-        /// <summary>
-        /// Gets a reference to the <see cref="Block8x8"/> at the given row and column index from <see cref="IJpegComponent.SpectralBlocks"/>
-        /// </summary>
-        public static ref Block8x8 GetBlockReference(this IJpegComponent component, int bx, int by)
-        {
-            return ref component.SpectralBlocks[bx, by];
-        }
-    }
-}
\ No newline at end of file
diff --git a/src/ImageSharp/Formats/Jpeg/Common/Decoder/IJpegComponent.cs b/src/ImageSharp/Formats/Jpeg/Common/Decoder/IJpegComponent.cs
index 4109fc10e..de9f75dc1 100644
--- a/src/ImageSharp/Formats/Jpeg/Common/Decoder/IJpegComponent.cs
+++ b/src/ImageSharp/Formats/Jpeg/Common/Decoder/IJpegComponent.cs
@@ -42,5 +42,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
         /// We need to apply IDCT and dequantiazition to transform them into color-space blocks.
         /// </summary>
         Buffer2D<Block8x8> SpectralBlocks { get; }
+
+        /// <summary>
+        /// Gets a reference to the <see cref="Block8x8"/> at the given row and column index from <see cref="SpectralBlocks"/>
+        /// </summary>
+        /// <param name="column">The column</param>
+        /// <param name="row">The row</param>
+        /// <returns>The <see cref="Block8x8"/></returns>
+        ref Block8x8 GetBlockReference(int column, int row);
     }
 }
\ No newline at end of file
diff --git a/src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigComponent.cs b/src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigComponent.cs
index e83dd75a5..e2f21bd1c 100644
--- a/src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigComponent.cs
+++ b/src/ImageSharp/Formats/Jpeg/GolangPort/Components/Decoder/OrigComponent.cs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Formats.Jpeg.Common;
 using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
 using SixLabors.ImageSharp.Memory;
@@ -237,6 +238,12 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort.Components.Decoder
             this.SamplingFactors = new Size(h, v);
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public ref Block8x8 GetBlockReference(int column, int row)
+        {
+            return ref this.SpectralBlocks[column, row];
+        }
+
         public void Dispose()
         {
             this.SpectralBlocks.Dispose();
diff --git a/src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsFrameComponent.cs b/src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsFrameComponent.cs
index 7d195374a..747e6107e 100644
--- a/src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsFrameComponent.cs
+++ b/src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsFrameComponent.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Formats.Jpeg.Common;
 using SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder;
 using SixLabors.ImageSharp.Memory;
@@ -130,14 +131,20 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
                 this.SubSamplingDivisors = c0.SamplingFactors.DivideBy(this.SamplingFactors);
             }
 
-            this.SpectralBlocks = this.memoryManager.Allocate2D<Block8x8>(this.SizeInBlocks.Width, this.SizeInBlocks.Height, true);
+            this.SpectralBlocks = this.memoryManager.Allocate2D<Block8x8>(this.BlocksPerColumnForMcu, this.BlocksPerLineForMcu + 1, true);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public ref Block8x8 GetBlockReference(int column, int row)
+        {
+            int offset = ((this.WidthInBlocks + 1) * row) + column;
+            return ref Unsafe.Add(ref MemoryMarshal.GetReference(this.SpectralBlocks.Span), offset);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public int GetBlockBufferOffset(int row, int col)
         {
-            // return 64 * (((this.WidthInBlocks + 1) * row) + col);
-            return 64 * ((this.WidthInBlocks * row) + col);
+            return 64 * (((this.WidthInBlocks + 1) * row) + col);
         }
     }
 }
\ No newline at end of file
diff --git a/tests/ImageSharp.Tests/Formats/Jpg/Utils/LibJpegTools.ComponentData.cs b/tests/ImageSharp.Tests/Formats/Jpg/Utils/LibJpegTools.ComponentData.cs
index 4cfaa6e61..a003f749e 100644
--- a/tests/ImageSharp.Tests/Formats/Jpg/Utils/LibJpegTools.ComponentData.cs
+++ b/tests/ImageSharp.Tests/Formats/Jpg/Utils/LibJpegTools.ComponentData.cs
@@ -184,6 +184,11 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg.Utils
                 }
             }
 
+            public ref Block8x8 GetBlockReference(int column, int row)
+            {
+                throw new NotImplementedException();
+            }
+
             public static bool operator ==(ComponentData left, ComponentData right)
             {
                 return Object.Equals(left, right);