WIP Replace Jpeg Decoder

ImageSharp.sln

@@ -49,9 +49,12 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "samples", "samples", "{7CC6
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "AvatarWithRoundedCorner", "samples\AvatarWithRoundedCorner\AvatarWithRoundedCorner.csproj", "{844FC582-4E78-4371-847D-EFD4D1103578}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ChangeDefaultEncoderOptions", "samples\ChangeDefaultEncoderOptions\ChangeDefaultEncoderOptions.csproj", "{07EE511D-4BAB-4323-BAFC-3AF2BF9366F0}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ChangeDefaultEncoderOptions", "samples\ChangeDefaultEncoderOptions\ChangeDefaultEncoderOptions.csproj", "{07EE511D-4BAB-4323-BAFC-3AF2BF9366F0}"
 EndProject
 Global
+	GlobalSection(Performance) = preSolution
+		HasPerformanceSessions = true
+	EndGlobalSection
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
 		Debug|x64 = Debug|x64

src/ImageSharp/Common/Extensions/ListExtensions.cs

@@ -0,0 +1,48 @@
+// <copyright file="ListExtensions.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Common.Extensions
+{
+    using System.Collections.Generic;
+
+    /// <summary>
+    /// Encapsulates a series of time saving extension methods to the <see cref="T:System.Collections.Generic.List"/> class.
+    /// </summary>
+    internal static class ListExtensions
+    {
+        /// <summary>
+        /// Inserts an item at the given index automatically expanding the capacity if required.
+        /// </summary>
+        /// <typeparam name="T">The type of object within the list</typeparam>
+        /// <param name="list">The list</param>
+        /// <param name="index">The index</param>
+        /// <param name="item">The item to insert</param>
+        public static void SafeInsert<T>(this List<T> list, int index, T item)
+        {
+            if (index >= list.Count)
+            {
+                list.Add(item);
+            }
+            else
+            {
+                list[index] = item;
+            }
+        }
+
+        /// <summary>
+        /// Removes the last element from a list and returns that element. This method changes the length of the list.
+        /// </summary>
+        /// <typeparam name="T">The type of object within the list</typeparam>
+        /// <param name="list">The list</param>
+        /// <returns>The last element in the specified sequence.</returns>
+        public static T Pop<T>(this List<T> list)
+        {
+            int last = list.Count - 1;
+            T item = list[last];
+            list.RemoveAt(last);
+            return item;
+        }
+    }
+}

src/ImageSharp/Common/Extensions/StreamExtensions.cs

@@ -27,7 +27,7 @@ public static void Skip(this Stream stream, int count)
 
             if (stream.CanSeek)
             {
-                stream.Position += count;
+                stream.Seek(count, SeekOrigin.Current); // Position += count;
             }
             else
             {

src/ImageSharp/Formats/Jpeg/JpegDecoder.cs

@@ -5,8 +5,6 @@
 
 namespace ImageSharp.Formats
 {
-    using System;
-    using System.Collections.Generic;
     using System.IO;
 
     using ImageSharp.PixelFormats;
@@ -27,10 +25,11 @@ public Image<TPixel> Decode<TPixel>(Configuration configuration, Stream stream)
         {
             Guard.NotNull(stream, "stream");
 
-            using (JpegDecoderCore decoder = new JpegDecoderCore(configuration, this))
+            // using (var decoder = new JpegDecoderCore(configuration, this))
+            using (var decoder = new Jpeg.Port.JpegDecoderCore(configuration, this))
             {
                 return decoder.Decode<TPixel>(stream);
             }
         }
     }
-}
+}

src/ImageSharp/Formats/Jpeg/Port/Components/Adobe.cs

@@ -0,0 +1,74 @@
+// <copyright file="Adobe.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+// ReSharper disable InconsistentNaming
+namespace ImageSharp.Formats.Jpeg.Port.Components
+{
+    using System;
+
+    /// <summary>
+    /// Provides information about the Adobe marker segment
+    /// </summary>
+    internal struct Adobe : IEquatable<Adobe>
+    {
+        /// <summary>
+        /// The DCT Encode Version
+        /// </summary>
+        public short DCTEncodeVersion;
+
+        /// <summary>
+        /// 0x0 : (none)
+        /// Bit 15 : Encoded with Blend=1 downsampling
+        /// </summary>
+        public short APP14Flags0;
+
+        /// <summary>
+        /// 0x0 : (none)
+        /// </summary>
+        public short APP14Flags1;
+
+        /// <summary>
+        /// Determines the colorspace transform
+        /// 00 : Unknown (RGB or CMYK)
+        /// 01 : YCbCr
+        /// 02 : YCCK
+        /// </summary>
+        public byte ColorTransform;
+
+        /// <inheritdoc/>
+        public bool Equals(Adobe other)
+        {
+            return this.DCTEncodeVersion == other.DCTEncodeVersion
+                && this.APP14Flags0 == other.APP14Flags0
+                && this.APP14Flags1 == other.APP14Flags1
+                && this.ColorTransform == other.ColorTransform;
+        }
+
+        /// <inheritdoc/>
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(null, obj))
+            {
+                return false;
+            }
+
+            return obj is Adobe && this.Equals((Adobe)obj);
+        }
+
+        /// <inheritdoc/>
+        public override int GetHashCode()
+        {
+            unchecked
+            {
+                // TODO: Merge and use HashCodeHelpers
+                int hashCode = this.DCTEncodeVersion.GetHashCode();
+                hashCode = (hashCode * 397) ^ this.APP14Flags0.GetHashCode();
+                hashCode = (hashCode * 397) ^ this.APP14Flags1.GetHashCode();
+                hashCode = (hashCode * 397) ^ this.ColorTransform.GetHashCode();
+                return hashCode;
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Port/Components/Component.cs

@@ -0,0 +1,44 @@
+// <copyright file="Component.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats.Jpeg.Port.Components
+{
+    using System;
+    using System.Numerics;
+    using ImageSharp.Memory;
+
+    /// <summary>
+    /// Represents a component block
+    /// </summary>
+    internal struct Component : IDisposable
+    {
+        /// <summary>
+        /// Gets or sets the output
+        /// </summary>
+        public Buffer<short> Output;
+
+        /// <summary>
+        /// Gets or sets the scaling factors
+        /// </summary>
+        public Vector2 Scale;
+
+        /// <summary>
+        /// Gets or sets the number of blocks per line
+        /// </summary>
+        public int BlocksPerLine;
+
+        /// <summary>
+        /// Gets or sets the number of blocks per column
+        /// </summary>
+        public int BlocksPerColumn;
+
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            this.Output?.Dispose();
+            this.Output = null;
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Port/Components/ComponentBlocks.cs

@@ -0,0 +1,34 @@
+// <copyright file="Components.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats.Jpeg.Port.Components
+{
+    using System;
+
+    /// <summary>
+    /// Contains all the decoded component blocks
+    /// </summary>
+    internal sealed class ComponentBlocks : IDisposable
+    {
+        /// <summary>
+        /// Gets or sets the component blocks
+        /// </summary>
+        public Component[] Components { get; set; }
+
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            if (this.Components != null)
+            {
+                for (int i = 0; i < this.Components.Length; i++)
+                {
+                    this.Components[i].Dispose();
+                }
+
+                this.Components = null;
+            }
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Port/Components/FileMarker.cs

@@ -0,0 +1,59 @@
+// <copyright file="HuffmanTables.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Formats.Jpeg.Port.Components
+{
+    /// <summary>
+    /// Represents a jpeg file marker
+    /// </summary>
+    internal struct FileMarker
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FileMarker"/> struct.
+        /// </summary>
+        /// <param name="marker">The marker</param>
+        /// <param name="position">The position within the stream</param>
+        public FileMarker(ushort marker, long position)
+        {
+            this.Marker = marker;
+            this.Position = position;
+            this.Invalid = false;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FileMarker"/> struct.
+        /// </summary>
+        /// <param name="marker">The marker</param>
+        /// <param name="position">The position within the stream</param>
+        /// <param name="invalid">Whether the current marker is invalid</param>
+        public FileMarker(ushort marker, long position, bool invalid)
+        {
+            this.Marker = marker;
+            this.Position = position;
+            this.Invalid = invalid;
+        }
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the current marker is invalid
+        /// </summary>
+        public bool Invalid { get; set; }
+
+        /// <summary>
+        /// Gets the position of the marker within a stream
+        /// </summary>
+        public ushort Marker { get; }
+
+        /// <summary>
+        /// Gets the position of the marker within a stream
+        /// </summary>
+        public long Position { get; }
+
+        /// <inheritdoc/>
+        public override string ToString()
+        {
+            return this.Marker.ToString("X");
+        }
+    }
+}