A bit more gif encoder work

Not going well 😦


Former-commit-id: 0fc05546fcc3a29e61620da83b7421ee4601f18e
Former-commit-id: 13403576c1acfa541456e97568852d845e9a8a42
Former-commit-id: f81fa27c751ee3171e9e9f330133d2bfa671d081

old/src/ImageProcessor/Imaging/Quantizers/IQuantizer.cs

@@ -4,7 +4,7 @@
 //   Licensed under the Apache License, Version 2.0.
 // </copyright>
 // <summary>
-//   The Quantizer interface for allowing quantization of images.
+//   Encapsulates methods to calculate the color palette of an image.
 // </summary>
 // --------------------------------------------------------------------------------------------------------------------
 
@@ -13,7 +13,7 @@ namespace ImageProcessor.Imaging.Quantizers
     using System.Drawing;
 
     /// <summary>
-    /// The Quantizer interface for allowing quantization of images.
+    /// Encapsulates methods to calculate the color palette of an image.
     /// </summary>
     public interface IQuantizer
     {

src/ImageProcessor/Common/Extensions/ByteExtensions.cs

@@ -25,14 +25,14 @@
                 result = new byte[bytes.Length * 8 / bits];
 
                 int factor = (int)Math.Pow(2, bits) - 1;
-                int mask = (0xFF >> (8 - bits));
+                int mask = 0xFF >> (8 - bits);
                 int resultOffset = 0;
 
                 foreach (byte b in bytes)
                 {
                     for (int shift = 0; shift < 8; shift += bits)
                     {
-                        int colorIndex = (((b) >> (8 - bits - shift)) & mask) * (255 / factor);
+                        int colorIndex = ((b >> (8 - bits - shift)) & mask) * (255 / factor);
 
                         result[resultOffset] = (byte)colorIndex;
 

src/ImageProcessor/Formats/Gif/GifDecoderCore.cs

@@ -32,6 +32,8 @@
             this.image = image;
 
             this.currentStream = stream;
+
+            // Skip the identifier
             this.currentStream.Seek(6, SeekOrigin.Current);
             this.ReadLogicalScreenDescriptor();
 

src/ImageProcessor/Formats/Gif/GifEncoder.cs

@@ -2,7 +2,6 @@
 namespace ImageProcessor.Formats
 {
     using System;
-    using System.Diagnostics.CodeAnalysis;
     using System.IO;
 
     public class GifEncoder : IImageEncoder
@@ -32,10 +31,7 @@ namespace ImageProcessor.Formats
         /// <summary>
         /// Gets the default file extension for this encoder.
         /// </summary>
-        public string Extension
+        public string Extension => "GIF";
-        {
-            get { return "GIF"; }
-        }
 
         /// <summary>
         /// Returns a value indicating whether the <see cref="IImageDecoder"/> supports the specified
@@ -53,6 +49,11 @@ namespace ImageProcessor.Formats
             return extension.Equals("GIF", StringComparison.OrdinalIgnoreCase);
         }
 
+        /// <summary>
+        /// Encodes the image to the specified stream from the <see cref="ImageBase"/>.
+        /// </summary>
+        /// <param name="image">The <see cref="ImageBase"/> to encode from.</param>
+        /// <param name="stream">The <see cref="Stream"/> to encode the image data to.</param>
         public void Encode(ImageBase image, Stream stream)
         {
             Guard.NotNull(image, "image");
@@ -73,6 +74,8 @@ namespace ImageProcessor.Formats
 
             this.WriteGlobalLogicalScreenDescriptor(stream, descriptor);
 
+
+
             throw new System.NotImplementedException();
         }
 
@@ -80,15 +83,24 @@ namespace ImageProcessor.Formats
         {
             this.WriteShort(stream, descriptor.Width);
             this.WriteShort(stream, descriptor.Width);
-            int bitdepth = this.GetBitsNeededForColorDepth(descriptor.GlobalColorTableSize) - 1;
+            int size = descriptor.GlobalColorTableSize;
-            int packed = 0x80 | // 1   : global color table flag = 1 (gct used)
+            int bitdepth = this.GetBitsNeededForColorDepth(size) - 1;
+            int packed = 0x80 | // 1   : global color table flag = 1 (GCT used)
                          0x70 | // 2-4 : color resolution
-                         0x00 | // 5   : gct sort flag = 0
+                         0x00 | // 5   : GCT sort flag = 0
-                         bitdepth; // 6-8 : gct size`
+                         bitdepth; // 6-8 : GCT size assume 1:1
 
             this.WriteByte(stream, packed);
             this.WriteByte(stream, descriptor.BackgroundColorIndex); // Background Color Index
             this.WriteByte(stream, descriptor.PixelAspectRatio); // Pixel aspect ratio
+
+            // Write the global color table.
+            this.WriteColorTable(stream, size);
+        }
+
+        private void WriteColorTable(Stream stream, int size)
+        {
+
         }
 
         /// <summary>

src/ImageProcessor/Formats/Gif/Quantizer/IQuantizer.cs

@@ -0,0 +1,27 @@
+// --------------------------------------------------------------------------------------------------------------------
+// <copyright file="IQuantizer.cs" company="James South">
+//   Copyright © James South and contributors.
+//   Licensed under the Apache License, Version 2.0.
+// </copyright>
+// <summary>
+//   Provides methods for allowing quantization of images pixels.
+// </summary>
+// --------------------------------------------------------------------------------------------------------------------
+
+namespace ImageProcessor.Formats
+{
+    /// <summary>
+    /// Provides methods for allowing quantization of images pixels.
+    /// </summary>
+    public interface IQuantizer
+    {
+        /// <summary>
+        /// Quantize an image and return the resulting output pixels.
+        /// </summary>
+        /// <param name="image">The image to quantize.</param>
+        /// <returns>
+        /// A <see cref="T:byte[]"/> representing a quantized version of the image pixels.
+        /// </returns>
+        byte[] Quantize(ImageBase image);
+    }
+}

src/ImageProcessor/Formats/Gif/Quantizer/OctreeQuantizer.cs

@@ -0,0 +1,55 @@
+// --------------------------------------------------------------------------------------------------------------------
+// <copyright file="OctreeQuantizer.cs" company="James South">
+//   Copyright © James South and contributors.
+//   Licensed under the Apache License, Version 2.0.
+// </copyright>
+// <summary>
+//   Encapsulates methods to calculate the color palette of an image using an Octree pattern.
+//   <see href="http://msdn.microsoft.com/en-us/library/aa479306.aspx" />
+// </summary>
+// --------------------------------------------------------------------------------------------------------------------
+
+namespace ImageProcessor.Formats
+{
+    /// <summary>
+    /// Encapsulates methods to calculate the color palette of an image using an Octree pattern.
+    /// <see href="http://msdn.microsoft.com/en-us/library/aa479306.aspx"/>
+    /// </summary>
+    public class OctreeQuantizer : Quantizer
+    {
+        /// <summary>
+        /// Maximum allowed color depth
+        /// </summary>
+        private readonly int maxColors;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OctreeQuantizer"/> class.
+        /// </summary>
+        /// <remarks>
+        /// The Octree quantizer is a two pass algorithm. The initial pass sets up the Octree,
+        /// the second pass quantizes a color based on the nodes in the tree.
+        /// <para>
+        /// Defaults to return a maximum of 255 colors plus transparency with 8 significant bits.
+        /// </para>
+        /// </remarks>
+        public OctreeQuantizer()
+            : this(255, 8)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OctreeQuantizer"/> class. 
+        /// </summary>
+        /// <remarks>
+        /// The Octree quantizer is a two pass algorithm. The initial pass sets up the Octree,
+        /// the second pass quantizes a color based on the nodes in the tree
+        /// </remarks>
+        /// <param name="maxColors">The maximum number of colors to return</param>
+        /// <param name="maxColorBits">The number of significant bits</param>
+        public OctreeQuantizer(int maxColors, int maxColorBits)
+            : base(false)
+        {
+            Guard.LessEquals(maxColors, 255, "maxColors");
+        }
+    }
+}

src/ImageProcessor/Formats/Gif/Quantizer/Quantizer.cs

@@ -0,0 +1,51 @@
+// --------------------------------------------------------------------------------------------------------------------
+// <copyright file="Quantizer.cs" company="James South">
+//   Copyright © James South and contributors.
+//   Licensed under the Apache License, Version 2.0.
+// </copyright>
+// <summary>
+//   Encapsulates methods to calculate the color palette of an image.
+// </summary>
+// --------------------------------------------------------------------------------------------------------------------
+
+namespace ImageProcessor.Formats
+{
+    /// <summary>
+    /// Encapsulates methods to calculate the color palette of an image.
+    /// </summary>
+    public abstract class Quantizer : IQuantizer
+    {
+        /// <summary>
+        /// Flag used to indicate whether a single pass or two passes are needed for quantization.
+        /// </summary>
+        private readonly bool singlePass;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Quantizer"/> class. 
+        /// </summary>
+        /// <param name="singlePass">
+        /// If true, the quantization only needs to loop through the source pixels once
+        /// </param>
+        /// <remarks>
+        /// If you construct this class with a true value for singlePass, then the code will, when quantizing your image,
+        /// only call the 'QuantizeImage' function. If two passes are required, the code will call 'InitialQuantizeImage'
+        /// and then 'QuantizeImage'.
+        /// </remarks>
+        protected Quantizer(bool singlePass)
+        {
+            this.singlePass = singlePass;
+        }
+
+        /// <summary>
+        /// Quantize an image and return the resulting output pixels.
+        /// </summary>
+        /// <param name="image">The image to quantize.</param>
+        /// <returns>
+        /// A <see cref="T:byte[]"/> representing a quantized version of the image pixels.
+        /// </returns>
+        public byte[] Quantize(ImageBase image)
+        {
+            throw new System.NotImplementedException();
+        }
+    }
+}

src/ImageProcessor/Formats/Png/GrayscaleReader.cs

@@ -41,7 +41,7 @@ namespace ImageProcessor.Formats
         /// Reads the specified scanline.
         /// </summary>
         /// <param name="scanline">The scanline.</param>
-        /// <param name="pixels">The pixels, where the colors should be stored in RGBA format.</param>
+        /// <param name="pixels">The pixels, where the colors should be stored in BGRA format.</param>
         /// <param name="header">
         /// The header, which contains information about the png file, like
         /// the width of the image and the height.

src/ImageProcessor/Formats/Png/PaletteIndexReader.cs

@@ -47,7 +47,7 @@ namespace ImageProcessor.Formats
         /// Reads the specified scanline.
         /// </summary>
         /// <param name="scanline">The scanline.</param>
-        /// <param name="pixels">The pixels, where the colors should be stored in RGBA format.</param>
+        /// <param name="pixels">The pixels, where the colors should be stored in BGRA format.</param>
         /// <param name="header">The header, which contains information about the png file, like
         /// the width of the image and the height.</param>
         public void ReadScanline(byte[] scanline, byte[] pixels, PngHeader header)

src/ImageProcessor/Formats/Png/TrueColorReader.cs

@@ -41,7 +41,7 @@ namespace ImageProcessor.Formats
         /// Reads the specified scanline.
         /// </summary>
         /// <param name="scanline">The scanline.</param>
-        /// <param name="pixels">The pixels, where the colors should be stored in RGBA format.</param>
+        /// <param name="pixels">The pixels, where the colors should be stored in BGRA format.</param>
         /// <param name="header">The header, which contains information about the png file, like
         /// the width of the image and the height.</param>
         public void ReadScanline(byte[] scanline, byte[] pixels, PngHeader header)

src/ImageProcessor/ImageProcessor.csproj

@@ -52,6 +52,9 @@
     <Compile Include="Formats\Bmp\BmpEncoder.cs" />
     <Compile Include="Formats\Gif\GifDecoderCore.cs" />
     <Compile Include="Formats\Gif\GifEncoder.cs" />
+    <Compile Include="Formats\Gif\Quantizer\IQuantizer.cs" />
+    <Compile Include="Formats\Gif\Quantizer\OctreeQuantizer.cs" />
+    <Compile Include="Formats\Gif\Quantizer\Quantizer.cs" />
     <Compile Include="Formats\Png\PngDecoder.cs" />
     <Compile Include="Formats\Png\PngDecoderCore.cs" />
     <Compile Include="Formats\Png\PngEncoder.cs" />

src/ImageProcessor/ImageProcessor.csproj.DotSettings

@@ -7,6 +7,7 @@
 	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=encoders_005Cgif/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=formats_005Cbmp/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=formats_005Cgif/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=formats_005Cgif_005Cquantizer/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=formats_005Cjpg/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=formats_005Cpng/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/CodeInspection/NamespaceProvider/NamespaceFoldersToSkip/=numerics/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>

src/ImageProcessor/Settings.StyleCop

@@ -2,6 +2,8 @@
   <GlobalSettings>
     <CollectionProperty Name="RecognizedWords">
       <Value>cb</Value>
+      <Value>octree</Value>
+      <Value>quantizer</Value>
       <Value>cr</Value>
       <Value>EX</Value>
       <Value>png</Value>