From c8acc89ad629cfbfb8f16ebba09fe8d0dac35b77 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Fri, 22 Jan 2016 10:42:45 +1100
Subject: [PATCH] Png perf improvements + cleanup

Former-commit-id: ff6ee98a500cab9af4419b6bdcf2aecaaa24e380
Former-commit-id: 0c00eb6ac7ba50eca5e1ee3340c779d8626ae9fe
Former-commit-id: 17ff53ba48bb59112609d4efc1ed2c2edd0ede97
---
 .../Common/Extensions/ByteExtensions.cs       | 11 +++-----
 .../Formats/Png/GrayscaleReader.cs            |  2 +-
 .../Formats/Png/PaletteIndexReader.cs         |  2 +-
 src/ImageProcessor/Formats/Png/PngChunk.cs    | 11 +++-----
 .../Formats/Png/PngChunkTypes.cs              | 11 +++-----
 .../Formats/Png/PngColorTypeInformation.cs    | 11 +++-----
 src/ImageProcessor/Formats/Png/PngDecoder.cs  | 11 +++-----
 .../Formats/Png/PngDecoderCore.cs             | 25 +++----------------
 src/ImageProcessor/Formats/Png/PngEncoder.cs  |  5 ++--
 src/ImageProcessor/Formats/Png/PngHeader.cs   | 13 +++-------
 src/ImageProcessor/Formats/Png/README.md      |  2 ++
 .../Formats/Png/TrueColorReader.cs            |  2 +-
 ...ibOutputStream.cs => ZlibDeflateStream.cs} | 11 +++++---
 ...libInputStream.cs => ZlibInflateStream.cs} | 13 +++++++---
 14 files changed, 47 insertions(+), 83 deletions(-)
 rename src/ImageProcessor/Formats/Png/Zlib/{ZlibOutputStream.cs => ZlibDeflateStream.cs} (93%)
 rename src/ImageProcessor/Formats/Png/Zlib/{ZlibInputStream.cs => ZlibInflateStream.cs} (93%)

diff --git a/src/ImageProcessor/Common/Extensions/ByteExtensions.cs b/src/ImageProcessor/Common/Extensions/ByteExtensions.cs
index 1fc3784a7..aeca81560 100644
--- a/src/ImageProcessor/Common/Extensions/ByteExtensions.cs
+++ b/src/ImageProcessor/Common/Extensions/ByteExtensions.cs
@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="ByteExtensions.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="ByteExtensions.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Extension methods for the <see cref="byte" /> struct.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor
 {
diff --git a/src/ImageProcessor/Formats/Png/GrayscaleReader.cs b/src/ImageProcessor/Formats/Png/GrayscaleReader.cs
index 4dfc69d9a..1d91c8a45 100644
--- a/src/ImageProcessor/Formats/Png/GrayscaleReader.cs
+++ b/src/ImageProcessor/Formats/Png/GrayscaleReader.cs
@@ -8,7 +8,7 @@ namespace ImageProcessor.Formats
     /// <summary>
     /// Color reader for reading grayscale colors from a png file.
     /// </summary>
-    public sealed class GrayscaleReader : IColorReader
+    internal sealed class GrayscaleReader : IColorReader
     {
         /// <summary>
         /// Whether t also read the alpha channel.
diff --git a/src/ImageProcessor/Formats/Png/PaletteIndexReader.cs b/src/ImageProcessor/Formats/Png/PaletteIndexReader.cs
index af087701b..6128b1244 100644
--- a/src/ImageProcessor/Formats/Png/PaletteIndexReader.cs
+++ b/src/ImageProcessor/Formats/Png/PaletteIndexReader.cs
@@ -8,7 +8,7 @@ namespace ImageProcessor.Formats
     /// <summary>
     /// A color reader for reading palette indices from the png file.
     /// </summary>
-    public sealed class PaletteIndexReader : IColorReader
+    internal sealed class PaletteIndexReader : IColorReader
     {
         /// <summary>
         /// The palette.
diff --git a/src/ImageProcessor/Formats/Png/PngChunk.cs b/src/ImageProcessor/Formats/Png/PngChunk.cs
index cbd3f9cbe..5bee7c375 100644
--- a/src/ImageProcessor/Formats/Png/PngChunk.cs
+++ b/src/ImageProcessor/Formats/Png/PngChunk.cs
@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="PngChunk.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="PngChunk.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Stores header information about a chunk.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
diff --git a/src/ImageProcessor/Formats/Png/PngChunkTypes.cs b/src/ImageProcessor/Formats/Png/PngChunkTypes.cs
index 7f39a887d..bfb12961c 100644
--- a/src/ImageProcessor/Formats/Png/PngChunkTypes.cs
+++ b/src/ImageProcessor/Formats/Png/PngChunkTypes.cs
@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="PngChunkTypes.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="PngChunkTypes.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Contains a list of possible chunk type identifiers.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
diff --git a/src/ImageProcessor/Formats/Png/PngColorTypeInformation.cs b/src/ImageProcessor/Formats/Png/PngColorTypeInformation.cs
index cacb0fb1d..ec7c6fa66 100644
--- a/src/ImageProcessor/Formats/Png/PngColorTypeInformation.cs
+++ b/src/ImageProcessor/Formats/Png/PngColorTypeInformation.cs
@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="PngColorTypeInformation.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="PngColorTypeInformation.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Contains information that are required when loading a png with a specific color type.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
diff --git a/src/ImageProcessor/Formats/Png/PngDecoder.cs b/src/ImageProcessor/Formats/Png/PngDecoder.cs
index 9661f2536..d9e87d898 100644
--- a/src/ImageProcessor/Formats/Png/PngDecoder.cs
+++ b/src/ImageProcessor/Formats/Png/PngDecoder.cs
@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="PngDecoder.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="PngDecoder.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Encoder for generating an image out of a png encoded stream.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
diff --git a/src/ImageProcessor/Formats/Png/PngDecoderCore.cs b/src/ImageProcessor/Formats/Png/PngDecoderCore.cs
index 489d69eeb..6ecbe5a86 100644
--- a/src/ImageProcessor/Formats/Png/PngDecoderCore.cs
+++ b/src/ImageProcessor/Formats/Png/PngDecoderCore.cs
@@ -1,12 +1,7 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="PngDecoderCore.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="PngDecoderCore.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Performs the png decoding operation.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
@@ -21,11 +16,6 @@ namespace ImageProcessor.Formats
     /// </summary>
     internal class PngDecoderCore
     {
-        /// <summary>
-        /// The maximum chunk size.
-        /// </summary>
-        private const int MaxChunkSize = int.MaxValue / 4 * sizeof(float);
-
         /// <summary>
         /// The dictionary of available color types.
         /// </summary>
@@ -261,7 +251,6 @@ namespace ImageProcessor.Formats
             int filter = 0, column = -1;
 
             using (ZlibInputStream compressedStream = new ZlibInputStream(dataStream))
-            //using (InflaterInputStream compressedStream = new InflaterInputStream(dataStream))
             {
                 int readByte;
                 while ((readByte = compressedStream.ReadByte()) >= 0)
@@ -456,16 +445,8 @@ namespace ImageProcessor.Formats
         /// Reads the chunk data from the stream.
         /// </summary>
         /// <param name="chunk">The chunk.</param>
-        /// <exception cref="ArgumentOutOfRangeException">
-        /// Thrown if the chunk length exceeds the maximum allowable size.
-        /// </exception>
         private void ReadChunkData(PngChunk chunk)
         {
-            if (chunk.Length > MaxChunkSize)
-            {
-                throw new ArgumentOutOfRangeException($"Png chunk size '{chunk.Length}' exceeds the maximum '{MaxChunkSize}'");
-            }
-
             chunk.Data = new byte[chunk.Length];
             this.currentStream.Read(chunk.Data, 0, chunk.Length);
         }
diff --git a/src/ImageProcessor/Formats/Png/PngEncoder.cs b/src/ImageProcessor/Formats/Png/PngEncoder.cs
index 786d02a85..850cb5ee0 100644
--- a/src/ImageProcessor/Formats/Png/PngEncoder.cs
+++ b/src/ImageProcessor/Formats/Png/PngEncoder.cs
@@ -7,6 +7,7 @@ namespace ImageProcessor.Formats
 {
     using System;
     using System.IO;
+    using System.Threading.Tasks;
 
     /// <summary>
     /// Image encoder for writing image data to a stream in png format.
@@ -204,7 +205,7 @@ namespace ImageProcessor.Formats
 
             int rowLength = (imageBase.Width * 4) + 1;
 
-            for (int y = 0; y < imageBase.Height; y++)
+            Parallel.For(0, imageBase.Height, y =>
             {
                 byte compression = 0;
                 if (y > 0)
@@ -252,7 +253,7 @@ namespace ImageProcessor.Formats
                         data[dataOffset + 3] -= color.A;
                     }
                 }
-            }
+            });
 
             byte[] buffer;
             int bufferLength;
diff --git a/src/ImageProcessor/Formats/Png/PngHeader.cs b/src/ImageProcessor/Formats/Png/PngHeader.cs
index b4ccac005..9b7eacc2f 100644
--- a/src/ImageProcessor/Formats/Png/PngHeader.cs
+++ b/src/ImageProcessor/Formats/Png/PngHeader.cs
@@ -1,19 +1,14 @@
-// --------------------------------------------------------------------------------------------------------------------
-// <copyright file="PngHeader.cs" company="James Jackson-South">
-//   Copyright (c) James Jackson-South and contributors.
-//   Licensed under the Apache License, Version 2.0.
+// <copyright file="PngHeader.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
 // </copyright>
-// <summary>
-//   Represents the png header chunk.
-// </summary>
-// --------------------------------------------------------------------------------------------------------------------
 
 namespace ImageProcessor.Formats
 {
     /// <summary>
     /// Represents the png header chunk.
     /// </summary>
-    public sealed class PngHeader
+    internal sealed class PngHeader
     {
         /// <summary>
         /// Gets or sets the dimension in x-direction of the image in pixels.
diff --git a/src/ImageProcessor/Formats/Png/README.md b/src/ImageProcessor/Formats/Png/README.md
index 0b5bd8c81..8ade37956 100644
--- a/src/ImageProcessor/Formats/Png/README.md
+++ b/src/ImageProcessor/Formats/Png/README.md
@@ -2,3 +2,5 @@
 
 https://github.com/yufeih/Nine.Imaging/
 https://imagetools.codeplex.com/
+https://github.com/leonbloy/pngcs
+
diff --git a/src/ImageProcessor/Formats/Png/TrueColorReader.cs b/src/ImageProcessor/Formats/Png/TrueColorReader.cs
index c292fcd56..74028967b 100644
--- a/src/ImageProcessor/Formats/Png/TrueColorReader.cs
+++ b/src/ImageProcessor/Formats/Png/TrueColorReader.cs
@@ -9,7 +9,7 @@ namespace ImageProcessor.Formats
     /// Color reader for reading true colors from a png file. Only colors
     /// with 24 or 32 bit (3 or 4 bytes) per pixel are supported at the moment.
     /// </summary>
-    public sealed class TrueColorReader : IColorReader
+    internal sealed class TrueColorReader : IColorReader
     {
         /// <summary>
         /// Whether t also read the alpha channel.
diff --git a/src/ImageProcessor/Formats/Png/Zlib/ZlibOutputStream.cs b/src/ImageProcessor/Formats/Png/Zlib/ZlibDeflateStream.cs
similarity index 93%
rename from src/ImageProcessor/Formats/Png/Zlib/ZlibOutputStream.cs
rename to src/ImageProcessor/Formats/Png/Zlib/ZlibDeflateStream.cs
index 9af156d06..efb57eed2 100644
--- a/src/ImageProcessor/Formats/Png/Zlib/ZlibOutputStream.cs
+++ b/src/ImageProcessor/Formats/Png/Zlib/ZlibDeflateStream.cs
@@ -1,4 +1,4 @@
-// <copyright file="ZlibOutputStream.cs" company="James Jackson-South">
+// <copyright file="ZlibDeflateStream.cs" company="James Jackson-South">
 // Copyright (c) James Jackson-South and contributors.
 // Licensed under the Apache License, Version 2.0.
 // </copyright>
@@ -9,7 +9,10 @@ namespace ImageProcessor.Formats
     using System.IO;
     using System.IO.Compression;
 
-    internal sealed class ZlibOutputStream : Stream
+    /// <summary>
+    /// Provides methods and properties for compressing streams by using the Zlib Deflate algorithm.
+    /// </summary>
+    internal sealed class ZlibDeflateStream : Stream
     {
         /// <summary>
         /// The raw stream containing the uncompressed image data.
@@ -38,11 +41,11 @@ namespace ImageProcessor.Formats
         private DeflateStream deflateStream;
 
         /// <summary>
-        /// Initializes a new instance of <see cref="ZlibOutputStream"/>
+        /// Initializes a new instance of <see cref="ZlibDeflateStream"/>
         /// </summary>
         /// <param name="stream">The stream to compress.</param>
         /// <param name="compressionLevel">The compression level.</param>
-        public ZlibOutputStream(Stream stream, int compressionLevel)
+        public ZlibDeflateStream(Stream stream, int compressionLevel)
         {
             this.rawStream = stream;
 
diff --git a/src/ImageProcessor/Formats/Png/Zlib/ZlibInputStream.cs b/src/ImageProcessor/Formats/Png/Zlib/ZlibInflateStream.cs
similarity index 93%
rename from src/ImageProcessor/Formats/Png/Zlib/ZlibInputStream.cs
rename to src/ImageProcessor/Formats/Png/Zlib/ZlibInflateStream.cs
index bcbd5d3bd..ebf19a285 100644
--- a/src/ImageProcessor/Formats/Png/Zlib/ZlibInputStream.cs
+++ b/src/ImageProcessor/Formats/Png/Zlib/ZlibInflateStream.cs
@@ -1,11 +1,18 @@
-
+// <copyright file="ZlibInflateStream.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
 namespace ImageProcessor.Formats
 {
     using System;
     using System.IO;
     using System.IO.Compression;
 
-    internal sealed class ZlibInputStream : Stream
+    /// <summary>
+    /// Provides methods and properties for decompressing streams by using the Zlib Deflate algorithm.
+    /// </summary>
+    internal sealed class ZlibInflateStream : Stream
     {
         /// <summary>
         /// A value indicating whether this instance of the given entity has been disposed.
@@ -51,7 +58,7 @@ namespace ImageProcessor.Formats
         // The stream responsible for decompressing the input stream.
         private DeflateStream deflateStream;
 
-        public ZlibInputStream(Stream stream)
+        public ZlibInflateStream(Stream stream)
         {
             this.rawStream = stream;