mirror of https://github.com/SixLabors/ImageSharp
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
1531 lines
62 KiB
1531 lines
62 KiB
// Copyright (c) Six Labors and contributors.
|
|
// Licensed under the Apache License, Version 2.0.
|
|
|
|
using System;
|
|
using System.Buffers.Binary;
|
|
using System.Collections.Generic;
|
|
using System.IO;
|
|
using System.Linq;
|
|
using System.Runtime.CompilerServices;
|
|
using System.Runtime.InteropServices;
|
|
using System.Text;
|
|
using SixLabors.ImageSharp.Advanced;
|
|
using SixLabors.ImageSharp.Common.Helpers;
|
|
using SixLabors.ImageSharp.Formats.Png.Filters;
|
|
using SixLabors.ImageSharp.Formats.Png.Zlib;
|
|
using SixLabors.ImageSharp.Memory;
|
|
using SixLabors.ImageSharp.MetaData;
|
|
using SixLabors.ImageSharp.MetaData.Profiles.Exif;
|
|
using SixLabors.ImageSharp.PixelFormats;
|
|
using SixLabors.Memory;
|
|
|
|
namespace SixLabors.ImageSharp.Formats.Png
|
|
{
|
|
/// <summary>
|
|
/// Performs the png decoding operation.
|
|
/// </summary>
|
|
internal sealed class PngDecoderCore
|
|
{
|
|
/// <summary>
|
|
/// The dictionary of available color types.
|
|
/// </summary>
|
|
private static readonly Dictionary<PngColorType, byte[]> ColorTypes = new Dictionary<PngColorType, byte[]>()
|
|
{
|
|
[PngColorType.Grayscale] = new byte[] { 1, 2, 4, 8, 16 },
|
|
[PngColorType.Rgb] = new byte[] { 8, 16 },
|
|
[PngColorType.Palette] = new byte[] { 1, 2, 4, 8 },
|
|
[PngColorType.GrayscaleWithAlpha] = new byte[] { 8, 16 },
|
|
[PngColorType.RgbWithAlpha] = new byte[] { 8, 16 }
|
|
};
|
|
|
|
/// <summary>
|
|
/// The amount to increment when processing each column per scanline for each interlaced pass
|
|
/// </summary>
|
|
private static readonly int[] Adam7ColumnIncrement = { 8, 8, 4, 4, 2, 2, 1 };
|
|
|
|
/// <summary>
|
|
/// The index to start at when processing each column per scanline for each interlaced pass
|
|
/// </summary>
|
|
private static readonly int[] Adam7FirstColumn = { 0, 4, 0, 2, 0, 1, 0 };
|
|
|
|
/// <summary>
|
|
/// The index to start at when processing each row per scanline for each interlaced pass
|
|
/// </summary>
|
|
private static readonly int[] Adam7FirstRow = { 0, 0, 4, 0, 2, 0, 1 };
|
|
|
|
/// <summary>
|
|
/// The amount to increment when processing each row per scanline for each interlaced pass
|
|
/// </summary>
|
|
private static readonly int[] Adam7RowIncrement = { 8, 8, 8, 4, 4, 2, 2 };
|
|
|
|
/// <summary>
|
|
/// Reusable buffer for reading chunk types.
|
|
/// </summary>
|
|
private readonly byte[] chunkTypeBuffer = new byte[4];
|
|
|
|
/// <summary>
|
|
/// Reusable buffer for reading chunk lengths.
|
|
/// </summary>
|
|
private readonly byte[] chunkLengthBuffer = new byte[4];
|
|
|
|
/// <summary>
|
|
/// Reusable buffer for reading crc values.
|
|
/// </summary>
|
|
private readonly byte[] crcBuffer = new byte[4];
|
|
|
|
/// <summary>
|
|
/// Reusable crc for validating chunks.
|
|
/// </summary>
|
|
private readonly Crc32 crc = new Crc32();
|
|
|
|
/// <summary>
|
|
/// The global configuration.
|
|
/// </summary>
|
|
private readonly Configuration configuration;
|
|
|
|
/// <summary>
|
|
/// Gets the encoding to use
|
|
/// </summary>
|
|
private readonly Encoding textEncoding;
|
|
|
|
/// <summary>
|
|
/// Gets or sets a value indicating whether the metadata should be ignored when the image is being decoded.
|
|
/// </summary>
|
|
private readonly bool ignoreMetadata;
|
|
|
|
/// <summary>
|
|
/// The stream to decode from.
|
|
/// </summary>
|
|
private Stream currentStream;
|
|
|
|
/// <summary>
|
|
/// The png header.
|
|
/// </summary>
|
|
private PngHeader header;
|
|
|
|
/// <summary>
|
|
/// The number of bytes per pixel.
|
|
/// </summary>
|
|
private int bytesPerPixel;
|
|
|
|
/// <summary>
|
|
/// The number of bytes per sample
|
|
/// </summary>
|
|
private int bytesPerSample;
|
|
|
|
/// <summary>
|
|
/// The number of bytes per scanline
|
|
/// </summary>
|
|
private int bytesPerScanline;
|
|
|
|
/// <summary>
|
|
/// The palette containing color information for indexed png's
|
|
/// </summary>
|
|
private byte[] palette;
|
|
|
|
/// <summary>
|
|
/// The palette containing alpha channel color information for indexed png's
|
|
/// </summary>
|
|
private byte[] paletteAlpha;
|
|
|
|
/// <summary>
|
|
/// A value indicating whether the end chunk has been reached.
|
|
/// </summary>
|
|
private bool isEndChunkReached;
|
|
|
|
/// <summary>
|
|
/// Previous scanline processed
|
|
/// </summary>
|
|
private IManagedByteBuffer previousScanline;
|
|
|
|
/// <summary>
|
|
/// The current scanline that is being processed
|
|
/// </summary>
|
|
private IManagedByteBuffer scanline;
|
|
|
|
/// <summary>
|
|
/// The index of the current scanline being processed
|
|
/// </summary>
|
|
private int currentRow = Adam7FirstRow[0];
|
|
|
|
/// <summary>
|
|
/// The current pass for an interlaced PNG
|
|
/// </summary>
|
|
private int pass;
|
|
|
|
/// <summary>
|
|
/// The current number of bytes read in the current scanline
|
|
/// </summary>
|
|
private int currentRowBytesRead;
|
|
|
|
/// <summary>
|
|
/// Gets or sets the png color type
|
|
/// </summary>
|
|
private PngColorType pngColorType;
|
|
|
|
/// <summary>
|
|
/// Represents any color in an 8 bit Rgb24 encoded png that should be transparent
|
|
/// </summary>
|
|
private Rgb24 rgb24Trans;
|
|
|
|
/// <summary>
|
|
/// Represents any color in a 16 bit Rgb24 encoded png that should be transparent
|
|
/// </summary>
|
|
private Rgb48 rgb48Trans;
|
|
|
|
/// <summary>
|
|
/// Represents any color in an 8 bit grayscale encoded png that should be transparent
|
|
/// </summary>
|
|
private byte luminanceTrans;
|
|
|
|
/// <summary>
|
|
/// Represents any color in a 16 bit grayscale encoded png that should be transparent
|
|
/// </summary>
|
|
private ushort luminance16Trans;
|
|
|
|
/// <summary>
|
|
/// Whether the image has transparency chunk and markers were decoded
|
|
/// </summary>
|
|
private bool hasTrans;
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the <see cref="PngDecoderCore"/> class.
|
|
/// </summary>
|
|
/// <param name="configuration">The configuration.</param>
|
|
/// <param name="options">The decoder options.</param>
|
|
public PngDecoderCore(Configuration configuration, IPngDecoderOptions options)
|
|
{
|
|
this.configuration = configuration ?? Configuration.Default;
|
|
this.textEncoding = options.TextEncoding ?? PngConstants.DefaultEncoding;
|
|
this.ignoreMetadata = options.IgnoreMetadata;
|
|
}
|
|
|
|
private MemoryAllocator MemoryAllocator => this.configuration.MemoryAllocator;
|
|
|
|
/// <summary>
|
|
/// Decodes the stream to the image.
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The pixel format.</typeparam>
|
|
/// <param name="stream">The stream containing image data. </param>
|
|
/// <exception cref="ImageFormatException">
|
|
/// Thrown if the stream does not contain and end chunk.
|
|
/// </exception>
|
|
/// <exception cref="ArgumentOutOfRangeException">
|
|
/// Thrown if the image is larger than the maximum allowable size.
|
|
/// </exception>
|
|
/// <returns>The decoded image</returns>
|
|
public Image<TPixel> Decode<TPixel>(Stream stream)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
var metadata = new ImageMetaData();
|
|
this.currentStream = stream;
|
|
this.currentStream.Skip(8);
|
|
Image<TPixel> image = null;
|
|
try
|
|
{
|
|
using (var deframeStream = new ZlibInflateStream(this.currentStream))
|
|
{
|
|
while (!this.isEndChunkReached && this.TryReadChunk(out PngChunk chunk))
|
|
{
|
|
try
|
|
{
|
|
switch (chunk.Type)
|
|
{
|
|
case PngChunkType.Header:
|
|
this.ReadHeaderChunk(chunk.Data.Array);
|
|
this.ValidateHeader();
|
|
break;
|
|
case PngChunkType.Physical:
|
|
this.ReadPhysicalChunk(metadata, chunk.Data.GetSpan());
|
|
break;
|
|
case PngChunkType.Data:
|
|
if (image is null)
|
|
{
|
|
this.InitializeImage(metadata, out image);
|
|
}
|
|
|
|
deframeStream.AllocateNewBytes(chunk.Length);
|
|
this.ReadScanlines(deframeStream.CompressedStream, image.Frames.RootFrame);
|
|
this.currentStream.Read(this.crcBuffer, 0, 4);
|
|
break;
|
|
case PngChunkType.Palette:
|
|
byte[] pal = new byte[chunk.Length];
|
|
Buffer.BlockCopy(chunk.Data.Array, 0, pal, 0, chunk.Length);
|
|
this.palette = pal;
|
|
break;
|
|
case PngChunkType.PaletteAlpha:
|
|
byte[] alpha = new byte[chunk.Length];
|
|
Buffer.BlockCopy(chunk.Data.Array, 0, alpha, 0, chunk.Length);
|
|
this.paletteAlpha = alpha;
|
|
this.AssignTransparentMarkers(alpha);
|
|
break;
|
|
case PngChunkType.Text:
|
|
this.ReadTextChunk(metadata, chunk.Data.Array, chunk.Length);
|
|
break;
|
|
case PngChunkType.Exif:
|
|
if (!this.ignoreMetadata)
|
|
{
|
|
byte[] exifData = new byte[chunk.Length];
|
|
Buffer.BlockCopy(chunk.Data.Array, 0, exifData, 0, chunk.Length);
|
|
metadata.ExifProfile = new ExifProfile(exifData);
|
|
}
|
|
|
|
break;
|
|
case PngChunkType.End:
|
|
this.isEndChunkReached = true;
|
|
break;
|
|
}
|
|
}
|
|
finally
|
|
{
|
|
chunk.Data?.Dispose(); // Data is rented in ReadChunkData()
|
|
}
|
|
}
|
|
}
|
|
|
|
if (image is null)
|
|
{
|
|
throw new ImageFormatException("PNG Image does not contain a data chunk");
|
|
}
|
|
|
|
return image;
|
|
}
|
|
finally
|
|
{
|
|
this.scanline?.Dispose();
|
|
this.previousScanline?.Dispose();
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the raw image information from the specified stream.
|
|
/// </summary>
|
|
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
|
|
public IImageInfo Identify(Stream stream)
|
|
{
|
|
var metadata = new ImageMetaData();
|
|
this.currentStream = stream;
|
|
this.currentStream.Skip(8);
|
|
try
|
|
{
|
|
while (!this.isEndChunkReached && this.TryReadChunk(out PngChunk chunk))
|
|
{
|
|
try
|
|
{
|
|
switch (chunk.Type)
|
|
{
|
|
case PngChunkType.Header:
|
|
this.ReadHeaderChunk(chunk.Data.Array);
|
|
this.ValidateHeader();
|
|
break;
|
|
case PngChunkType.Physical:
|
|
this.ReadPhysicalChunk(metadata, chunk.Data.GetSpan());
|
|
break;
|
|
case PngChunkType.Data:
|
|
this.SkipChunkDataAndCrc(chunk);
|
|
break;
|
|
case PngChunkType.Text:
|
|
this.ReadTextChunk(metadata, chunk.Data.Array, chunk.Length);
|
|
break;
|
|
case PngChunkType.End:
|
|
this.isEndChunkReached = true;
|
|
break;
|
|
}
|
|
}
|
|
finally
|
|
{
|
|
chunk.Data?.Dispose(); // Data is rented in ReadChunkData()
|
|
}
|
|
}
|
|
}
|
|
finally
|
|
{
|
|
this.scanline?.Dispose();
|
|
this.previousScanline?.Dispose();
|
|
}
|
|
|
|
if (this.header.Width == 0 && this.header.Height == 0)
|
|
{
|
|
throw new ImageFormatException("PNG Image does not contain a header chunk");
|
|
}
|
|
|
|
return new ImageInfo(new PixelTypeInfo(this.CalculateBitsPerPixel()), this.header.Width, this.header.Height, metadata);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the least significant bits from the byte pair with the others set to 0.
|
|
/// </summary>
|
|
/// <param name="buffer">The source buffer</param>
|
|
/// <param name="offset">THe offset</param>
|
|
/// <returns>The <see cref="int"/></returns>
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
private static byte ReadByteLittleEndian(ReadOnlySpan<byte> buffer, int offset)
|
|
{
|
|
return (byte)(((buffer[offset] & 0xFF) << 16) | (buffer[offset + 1] & 0xFF));
|
|
}
|
|
|
|
/// <summary>
|
|
/// Attempts to convert a byte array to a new array where each value in the original array is represented by the
|
|
/// specified number of bits.
|
|
/// </summary>
|
|
/// <param name="source">The bytes to convert from. Cannot be empty.</param>
|
|
/// <param name="bytesPerScanline">The number of bytes per scanline</param>
|
|
/// <param name="bits">The number of bits per value.</param>
|
|
/// <param name="buffer">The new array.</param>
|
|
/// <returns>The resulting <see cref="ReadOnlySpan{Byte}"/> array.</returns>
|
|
private bool TryScaleUpTo8BitArray(ReadOnlySpan<byte> source, int bytesPerScanline, int bits, out IManagedByteBuffer buffer)
|
|
{
|
|
if (bits >= 8)
|
|
{
|
|
buffer = null;
|
|
return false;
|
|
}
|
|
|
|
buffer = this.MemoryAllocator.AllocateManagedByteBuffer(bytesPerScanline * 8 / bits, AllocationOptions.Clean);
|
|
byte[] result = buffer.Array;
|
|
int mask = 0xFF >> (8 - bits);
|
|
int resultOffset = 0;
|
|
|
|
for (int i = 0; i < bytesPerScanline - 1; i++)
|
|
{
|
|
byte b = source[i];
|
|
for (int shift = 0; shift < 8; shift += bits)
|
|
{
|
|
int colorIndex = (b >> (8 - bits - shift)) & mask;
|
|
result[resultOffset] = (byte)colorIndex;
|
|
|
|
resultOffset++;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the data chunk containing physical dimension data.
|
|
/// </summary>
|
|
/// <param name="metadata">The metadata to read to.</param>
|
|
/// <param name="data">The data containing physical data.</param>
|
|
private void ReadPhysicalChunk(ImageMetaData metadata, ReadOnlySpan<byte> data)
|
|
{
|
|
// The pHYs chunk specifies the intended pixel size or aspect ratio for display of the image. It contains:
|
|
// Pixels per unit, X axis: 4 bytes (unsigned integer)
|
|
// Pixels per unit, Y axis: 4 bytes (unsigned integer)
|
|
// Unit specifier: 1 byte
|
|
//
|
|
// The following values are legal for the unit specifier:
|
|
// 0: unit is unknown
|
|
// 1: unit is the meter
|
|
//
|
|
// When the unit specifier is 0, the pHYs chunk defines pixel aspect ratio only; the actual size of the pixels remains unspecified.
|
|
int hResolution = BinaryPrimitives.ReadInt32BigEndian(data.Slice(0, 4));
|
|
int vResolution = BinaryPrimitives.ReadInt32BigEndian(data.Slice(4, 4));
|
|
byte unit = data[8];
|
|
|
|
metadata.ResolutionUnits = unit == byte.MinValue
|
|
? PixelResolutionUnit.AspectRatio
|
|
: PixelResolutionUnit.PixelsPerMeter;
|
|
|
|
metadata.HorizontalResolution = hResolution;
|
|
metadata.VerticalResolution = vResolution;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Initializes the image and various buffers needed for processing
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The type the pixels will be</typeparam>
|
|
/// <param name="metadata">The metadata information for the image</param>
|
|
/// <param name="image">The image that we will populate</param>
|
|
private void InitializeImage<TPixel>(ImageMetaData metadata, out Image<TPixel> image)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
image = new Image<TPixel>(this.configuration, this.header.Width, this.header.Height, metadata);
|
|
this.bytesPerPixel = this.CalculateBytesPerPixel();
|
|
this.bytesPerScanline = this.CalculateScanlineLength(this.header.Width) + 1;
|
|
this.bytesPerSample = 1;
|
|
if (this.header.BitDepth >= 8)
|
|
{
|
|
this.bytesPerSample = this.header.BitDepth / 8;
|
|
}
|
|
|
|
this.previousScanline = this.MemoryAllocator.AllocateManagedByteBuffer(this.bytesPerScanline, AllocationOptions.Clean);
|
|
this.scanline = this.configuration.MemoryAllocator.AllocateManagedByteBuffer(this.bytesPerScanline, AllocationOptions.Clean);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Calculates the correct number of bits per pixel for the given color type.
|
|
/// </summary>
|
|
/// <returns>The <see cref="int"/></returns>
|
|
private int CalculateBitsPerPixel()
|
|
{
|
|
switch (this.pngColorType)
|
|
{
|
|
case PngColorType.Grayscale:
|
|
case PngColorType.Palette:
|
|
return this.header.BitDepth;
|
|
case PngColorType.GrayscaleWithAlpha:
|
|
return this.header.BitDepth * 2;
|
|
case PngColorType.Rgb:
|
|
return this.header.BitDepth * 3;
|
|
case PngColorType.RgbWithAlpha:
|
|
return this.header.BitDepth * 4;
|
|
default:
|
|
throw new NotSupportedException("Unsupported PNG color type");
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Calculates the correct number of bytes per pixel for the given color type.
|
|
/// </summary>
|
|
/// <returns>The <see cref="int"/></returns>
|
|
private int CalculateBytesPerPixel()
|
|
{
|
|
switch (this.pngColorType)
|
|
{
|
|
case PngColorType.Grayscale:
|
|
return this.header.BitDepth == 16 ? 2 : 1;
|
|
|
|
case PngColorType.GrayscaleWithAlpha:
|
|
return this.header.BitDepth == 16 ? 4 : 2;
|
|
|
|
case PngColorType.Palette:
|
|
return 1;
|
|
|
|
case PngColorType.Rgb:
|
|
return this.header.BitDepth == 16 ? 6 : 3;
|
|
|
|
case PngColorType.RgbWithAlpha:
|
|
default:
|
|
return this.header.BitDepth == 16 ? 8 : 4;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Calculates the scanline length.
|
|
/// </summary>
|
|
/// <param name="width">The width of the row.</param>
|
|
/// <returns>
|
|
/// The <see cref="int"/> representing the length.
|
|
/// </returns>
|
|
private int CalculateScanlineLength(int width)
|
|
{
|
|
int mod = this.header.BitDepth == 16 ? 16 : 8;
|
|
int scanlineLength = width * this.header.BitDepth * this.bytesPerPixel;
|
|
|
|
int amount = scanlineLength % mod;
|
|
if (amount != 0)
|
|
{
|
|
scanlineLength += mod - amount;
|
|
}
|
|
|
|
return scanlineLength / mod;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the scanlines within the image.
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The pixel format.</typeparam>
|
|
/// <param name="dataStream">The <see cref="MemoryStream"/> containing data.</param>
|
|
/// <param name="image"> The pixel data.</param>
|
|
private void ReadScanlines<TPixel>(Stream dataStream, ImageFrame<TPixel> image)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
if (this.header.InterlaceMethod == PngInterlaceMode.Adam7)
|
|
{
|
|
this.DecodeInterlacedPixelData(dataStream, image);
|
|
}
|
|
else
|
|
{
|
|
this.DecodePixelData(dataStream, image);
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Decodes the raw pixel data row by row
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The pixel format.</typeparam>
|
|
/// <param name="compressedStream">The compressed pixel data stream.</param>
|
|
/// <param name="image">The image to decode to.</param>
|
|
private void DecodePixelData<TPixel>(Stream compressedStream, ImageFrame<TPixel> image)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
while (this.currentRow < this.header.Height)
|
|
{
|
|
int bytesRead = compressedStream.Read(this.scanline.Array, this.currentRowBytesRead, this.bytesPerScanline - this.currentRowBytesRead);
|
|
this.currentRowBytesRead += bytesRead;
|
|
if (this.currentRowBytesRead < this.bytesPerScanline)
|
|
{
|
|
return;
|
|
}
|
|
|
|
this.currentRowBytesRead = 0;
|
|
Span<byte> scanlineSpan = this.scanline.GetSpan();
|
|
|
|
switch ((FilterType)scanlineSpan[0])
|
|
{
|
|
case FilterType.None:
|
|
break;
|
|
|
|
case FilterType.Sub:
|
|
|
|
SubFilter.Decode(scanlineSpan, this.bytesPerPixel);
|
|
break;
|
|
|
|
case FilterType.Up:
|
|
|
|
UpFilter.Decode(scanlineSpan, this.previousScanline.GetSpan());
|
|
break;
|
|
|
|
case FilterType.Average:
|
|
|
|
AverageFilter.Decode(scanlineSpan, this.previousScanline.GetSpan(), this.bytesPerPixel);
|
|
break;
|
|
|
|
case FilterType.Paeth:
|
|
|
|
PaethFilter.Decode(scanlineSpan, this.previousScanline.GetSpan(), this.bytesPerPixel);
|
|
break;
|
|
|
|
default:
|
|
throw new ImageFormatException("Unknown filter type.");
|
|
}
|
|
|
|
this.ProcessDefilteredScanline(this.scanline.Array, image);
|
|
|
|
this.SwapBuffers();
|
|
this.currentRow++;
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Decodes the raw interlaced pixel data row by row
|
|
/// <see href="https://github.com/juehv/DentalImageViewer/blob/8a1a4424b15d6cc453b5de3f273daf3ff5e3a90d/DentalImageViewer/lib/jiu-0.14.3/net/sourceforge/jiu/codecs/PNGCodec.java"/>
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The pixel format.</typeparam>
|
|
/// <param name="compressedStream">The compressed pixel data stream.</param>
|
|
/// <param name="image">The current image.</param>
|
|
private void DecodeInterlacedPixelData<TPixel>(Stream compressedStream, ImageFrame<TPixel> image)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
while (true)
|
|
{
|
|
int numColumns = this.ComputeColumnsAdam7(this.pass);
|
|
|
|
if (numColumns == 0)
|
|
{
|
|
this.pass++;
|
|
|
|
// This pass contains no data; skip to next pass
|
|
continue;
|
|
}
|
|
|
|
int bytesPerInterlaceScanline = this.CalculateScanlineLength(numColumns) + 1;
|
|
|
|
while (this.currentRow < this.header.Height)
|
|
{
|
|
int bytesRead = compressedStream.Read(this.scanline.Array, this.currentRowBytesRead, bytesPerInterlaceScanline - this.currentRowBytesRead);
|
|
this.currentRowBytesRead += bytesRead;
|
|
if (this.currentRowBytesRead < bytesPerInterlaceScanline)
|
|
{
|
|
return;
|
|
}
|
|
|
|
this.currentRowBytesRead = 0;
|
|
|
|
Span<byte> scanSpan = this.scanline.Slice(0, bytesPerInterlaceScanline);
|
|
Span<byte> prevSpan = this.previousScanline.Slice(0, bytesPerInterlaceScanline);
|
|
|
|
switch ((FilterType)scanSpan[0])
|
|
{
|
|
case FilterType.None:
|
|
break;
|
|
|
|
case FilterType.Sub:
|
|
|
|
SubFilter.Decode(scanSpan, this.bytesPerPixel);
|
|
break;
|
|
|
|
case FilterType.Up:
|
|
|
|
UpFilter.Decode(scanSpan, prevSpan);
|
|
break;
|
|
|
|
case FilterType.Average:
|
|
|
|
AverageFilter.Decode(scanSpan, prevSpan, this.bytesPerPixel);
|
|
break;
|
|
|
|
case FilterType.Paeth:
|
|
|
|
PaethFilter.Decode(scanSpan, prevSpan, this.bytesPerPixel);
|
|
break;
|
|
|
|
default:
|
|
throw new ImageFormatException("Unknown filter type.");
|
|
}
|
|
|
|
Span<TPixel> rowSpan = image.GetPixelRowSpan(this.currentRow);
|
|
this.ProcessInterlacedDefilteredScanline(this.scanline.GetSpan(), rowSpan, Adam7FirstColumn[this.pass], Adam7ColumnIncrement[this.pass]);
|
|
|
|
this.SwapBuffers();
|
|
|
|
this.currentRow += Adam7RowIncrement[this.pass];
|
|
}
|
|
|
|
this.pass++;
|
|
this.previousScanline.Clear();
|
|
|
|
if (this.pass < 7)
|
|
{
|
|
this.currentRow = Adam7FirstRow[this.pass];
|
|
}
|
|
else
|
|
{
|
|
this.pass = 0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Processes the de-filtered scanline filling the image pixel data
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The pixel format.</typeparam>
|
|
/// <param name="defilteredScanline">The de-filtered scanline</param>
|
|
/// <param name="pixels">The image</param>
|
|
private void ProcessDefilteredScanline<TPixel>(ReadOnlySpan<byte> defilteredScanline, ImageFrame<TPixel> pixels)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
TPixel pixel = default;
|
|
Span<TPixel> rowSpan = pixels.GetPixelRowSpan(this.currentRow);
|
|
|
|
// Trim the first marker byte from the buffer
|
|
ReadOnlySpan<byte> trimmed = defilteredScanline.Slice(1, defilteredScanline.Length - 1);
|
|
|
|
// Convert 1, 2, and 4 bit pixel data into the 8 bit equivalent.
|
|
ReadOnlySpan<byte> scanlineSpan = this.TryScaleUpTo8BitArray(trimmed, this.bytesPerScanline, this.header.BitDepth, out IManagedByteBuffer buffer)
|
|
? buffer.GetSpan()
|
|
: trimmed;
|
|
|
|
switch (this.pngColorType)
|
|
{
|
|
case PngColorType.Grayscale:
|
|
|
|
int factor = 255 / ((int)Math.Pow(2, this.header.BitDepth) - 1);
|
|
|
|
if (!this.hasTrans)
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgb48 rgb48 = default;
|
|
for (int x = 0, o = 0; x < this.header.Width; x++, o += 2)
|
|
{
|
|
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgb48.R = luminance;
|
|
rgb48.G = luminance;
|
|
rgb48.B = luminance;
|
|
pixel.PackFromRgb48(rgb48);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
|
|
var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
|
|
for (int x = 0; x < this.header.Width; x++)
|
|
{
|
|
byte luminance = (byte)(scanlineSpan[x] * factor);
|
|
rgba32.R = luminance;
|
|
rgba32.G = luminance;
|
|
rgba32.B = luminance;
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgba64 rgba64 = default;
|
|
for (int x = 0, o = 0; x < this.header.Width; x++, o += 2)
|
|
{
|
|
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgba64.R = luminance;
|
|
rgba64.G = luminance;
|
|
rgba64.B = luminance;
|
|
rgba64.A = luminance.Equals(this.luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
|
|
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Rgba32 rgba32 = default;
|
|
for (int x = 0; x < this.header.Width; x++)
|
|
{
|
|
byte luminance = (byte)(scanlineSpan[x] * factor);
|
|
rgba32.R = luminance;
|
|
rgba32.G = luminance;
|
|
rgba32.B = luminance;
|
|
rgba32.A = luminance.Equals(this.luminanceTrans) ? byte.MinValue : byte.MaxValue;
|
|
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.GrayscaleWithAlpha:
|
|
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgba64 rgba64 = default;
|
|
for (int x = 0, o = 0; x < this.header.Width; x++, o += 4)
|
|
{
|
|
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgba64.R = luminance;
|
|
rgba64.G = luminance;
|
|
rgba64.B = luminance;
|
|
rgba64.A = alpha;
|
|
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Rgba32 rgba32 = default;
|
|
for (int x = 0; x < this.header.Width; x++)
|
|
{
|
|
int offset = x * this.bytesPerPixel;
|
|
byte luminance = scanlineSpan[offset];
|
|
byte alpha = scanlineSpan[offset + this.bytesPerSample];
|
|
|
|
rgba32.R = luminance;
|
|
rgba32.G = luminance;
|
|
rgba32.B = luminance;
|
|
rgba32.A = alpha;
|
|
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.Palette:
|
|
|
|
this.ProcessScanlineFromPalette(scanlineSpan, rowSpan);
|
|
|
|
break;
|
|
|
|
case PngColorType.Rgb:
|
|
|
|
if (!this.hasTrans)
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgb48 rgb48 = default;
|
|
for (int x = 0, o = 0; x < this.header.Width; x++, o += 6)
|
|
{
|
|
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
|
|
pixel.PackFromRgb48(rgb48);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
PixelOperations<TPixel>.Instance.PackFromRgb24Bytes(scanlineSpan, rowSpan, this.header.Width);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgb48 rgb48 = default;
|
|
Rgba64 rgba64 = default;
|
|
for (int x = 0, o = 0; x < this.header.Width; x++, o += 6)
|
|
{
|
|
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
|
|
|
|
rgba64.Rgb = rgb48;
|
|
rgba64.A = rgb48.Equals(this.rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
|
|
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
ReadOnlySpan<Rgb24> rgb24Span = MemoryMarshal.Cast<byte, Rgb24>(scanlineSpan);
|
|
for (int x = 0; x < this.header.Width; x++)
|
|
{
|
|
ref readonly Rgb24 rgb24 = ref rgb24Span[x];
|
|
Rgba32 rgba32 = default;
|
|
rgba32.Rgb = rgb24;
|
|
rgba32.A = rgb24.Equals(this.rgb24Trans) ? byte.MinValue : byte.MaxValue;
|
|
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.RgbWithAlpha:
|
|
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgba64 rgba64 = default;
|
|
for (int x = 0, o = 0; x < this.header.Width; x++, o += 8)
|
|
{
|
|
rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
|
|
rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 6, 2));
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
PixelOperations<TPixel>.Instance.PackFromRgba32Bytes(scanlineSpan, rowSpan, this.header.Width);
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
buffer?.Dispose();
|
|
}
|
|
|
|
/// <summary>
|
|
/// Processes the interlaced de-filtered scanline filling the image pixel data
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The pixel format.</typeparam>
|
|
/// <param name="defilteredScanline">The de-filtered scanline</param>
|
|
/// <param name="rowSpan">The current image row.</param>
|
|
/// <param name="pixelOffset">The column start index. Always 0 for none interlaced images.</param>
|
|
/// <param name="increment">The column increment. Always 1 for none interlaced images.</param>
|
|
private void ProcessInterlacedDefilteredScanline<TPixel>(ReadOnlySpan<byte> defilteredScanline, Span<TPixel> rowSpan, int pixelOffset = 0, int increment = 1)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
TPixel pixel = default;
|
|
|
|
// Trim the first marker byte from the buffer
|
|
ReadOnlySpan<byte> trimmed = defilteredScanline.Slice(1, defilteredScanline.Length - 1);
|
|
|
|
// Convert 1, 2, and 4 bit pixel data into the 8 bit equivalent.
|
|
ReadOnlySpan<byte> scanlineSpan = this.TryScaleUpTo8BitArray(trimmed, this.bytesPerScanline, this.header.BitDepth, out IManagedByteBuffer buffer)
|
|
? buffer.GetSpan()
|
|
: trimmed;
|
|
|
|
switch (this.pngColorType)
|
|
{
|
|
case PngColorType.Grayscale:
|
|
|
|
int factor = 255 / ((int)Math.Pow(2, this.header.BitDepth) - 1);
|
|
|
|
if (!this.hasTrans)
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgb48 rgb48 = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 2)
|
|
{
|
|
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgb48.R = luminance;
|
|
rgb48.G = luminance;
|
|
rgb48.B = luminance;
|
|
|
|
pixel.PackFromRgb48(rgb48);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// TODO: We should really be using Rgb24 here but IPixel does not have a PackFromRgb24 method.
|
|
var rgba32 = new Rgba32(0, 0, 0, byte.MaxValue);
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
|
|
{
|
|
byte luminance = (byte)(scanlineSpan[o] * factor);
|
|
rgba32.R = luminance;
|
|
rgba32.G = luminance;
|
|
rgba32.B = luminance;
|
|
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgba64 rgba64 = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 2)
|
|
{
|
|
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgba64.R = luminance;
|
|
rgba64.G = luminance;
|
|
rgba64.B = luminance;
|
|
rgba64.A = luminance.Equals(this.luminance16Trans) ? ushort.MinValue : ushort.MaxValue;
|
|
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Rgba32 rgba32 = default;
|
|
for (int x = pixelOffset; x < this.header.Width; x += increment)
|
|
{
|
|
byte luminance = (byte)(scanlineSpan[x] * factor);
|
|
rgba32.R = luminance;
|
|
rgba32.G = luminance;
|
|
rgba32.B = luminance;
|
|
rgba32.A = luminance.Equals(this.luminanceTrans) ? byte.MinValue : byte.MaxValue;
|
|
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.GrayscaleWithAlpha:
|
|
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgba64 rgba64 = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 4)
|
|
{
|
|
ushort luminance = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
ushort alpha = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgba64.R = luminance;
|
|
rgba64.G = luminance;
|
|
rgba64.B = luminance;
|
|
rgba64.A = alpha;
|
|
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Rgba32 rgba32 = default;
|
|
for (int x = pixelOffset; x < this.header.Width; x += increment)
|
|
{
|
|
int offset = x * this.bytesPerPixel;
|
|
byte luminance = scanlineSpan[offset];
|
|
byte alpha = scanlineSpan[offset + this.bytesPerSample];
|
|
rgba32.R = luminance;
|
|
rgba32.G = luminance;
|
|
rgba32.B = luminance;
|
|
rgba32.A = alpha;
|
|
|
|
pixel.PackFromRgba32(rgba32);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.Palette:
|
|
|
|
Span<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(this.palette);
|
|
|
|
if (this.paletteAlpha?.Length > 0)
|
|
{
|
|
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
|
|
// channel and we should try to read it.
|
|
Rgba32 rgba = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
|
|
{
|
|
int index = scanlineSpan[o];
|
|
rgba.A = this.paletteAlpha.Length > index ? this.paletteAlpha[index] : byte.MaxValue;
|
|
rgba.Rgb = palettePixels[index];
|
|
|
|
pixel.PackFromRgba32(rgba);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o++)
|
|
{
|
|
int index = scanlineSpan[o];
|
|
rgba.Rgb = palettePixels[index];
|
|
|
|
pixel.PackFromRgba32(rgba);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.Rgb:
|
|
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
if (this.hasTrans)
|
|
{
|
|
Rgb48 rgb48 = default;
|
|
Rgba64 rgba64 = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 6)
|
|
{
|
|
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
|
|
|
|
rgba64.Rgb = rgb48;
|
|
rgba64.A = rgb48.Equals(this.rgb48Trans) ? ushort.MinValue : ushort.MaxValue;
|
|
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Rgb48 rgb48 = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 6)
|
|
{
|
|
rgb48.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgb48.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgb48.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
|
|
pixel.PackFromRgb48(rgb48);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
if (this.hasTrans)
|
|
{
|
|
Rgba32 rgba = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
|
|
{
|
|
rgba.R = scanlineSpan[o];
|
|
rgba.G = scanlineSpan[o + this.bytesPerSample];
|
|
rgba.B = scanlineSpan[o + (2 * this.bytesPerSample)];
|
|
rgba.A = this.rgb24Trans.Equals(rgba.Rgb) ? byte.MinValue : byte.MaxValue;
|
|
|
|
pixel.PackFromRgba32(rgba);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
|
|
{
|
|
rgba.R = scanlineSpan[o];
|
|
rgba.G = scanlineSpan[o + this.bytesPerSample];
|
|
rgba.B = scanlineSpan[o + (2 * this.bytesPerSample)];
|
|
|
|
pixel.PackFromRgba32(rgba);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
}
|
|
|
|
break;
|
|
|
|
case PngColorType.RgbWithAlpha:
|
|
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
Rgba64 rgba64 = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += 8)
|
|
{
|
|
rgba64.R = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o, 2));
|
|
rgba64.G = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 2, 2));
|
|
rgba64.B = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 4, 2));
|
|
rgba64.A = BinaryPrimitives.ReadUInt16BigEndian(scanlineSpan.Slice(o + 6, 2));
|
|
pixel.PackFromRgba64(rgba64);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Rgba32 rgba = default;
|
|
for (int x = pixelOffset, o = 0; x < this.header.Width; x += increment, o += this.bytesPerPixel)
|
|
{
|
|
rgba.R = scanlineSpan[o];
|
|
rgba.G = scanlineSpan[o + this.bytesPerSample];
|
|
rgba.B = scanlineSpan[o + (2 * this.bytesPerSample)];
|
|
rgba.A = scanlineSpan[o + (3 * this.bytesPerSample)];
|
|
|
|
pixel.PackFromRgba32(rgba);
|
|
rowSpan[x] = pixel;
|
|
}
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
buffer?.Dispose();
|
|
}
|
|
|
|
/// <summary>
|
|
/// Decodes and assigns marker colors that identify transparent pixels in non indexed images
|
|
/// </summary>
|
|
/// <param name="alpha">The alpha tRNS array</param>
|
|
private void AssignTransparentMarkers(ReadOnlySpan<byte> alpha)
|
|
{
|
|
if (this.pngColorType == PngColorType.Rgb)
|
|
{
|
|
if (alpha.Length >= 6)
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
ushort rc = BinaryPrimitives.ReadUInt16LittleEndian(alpha.Slice(0, 2));
|
|
ushort gc = BinaryPrimitives.ReadUInt16LittleEndian(alpha.Slice(2, 2));
|
|
ushort bc = BinaryPrimitives.ReadUInt16LittleEndian(alpha.Slice(4, 2));
|
|
this.rgb48Trans = new Rgb48(rc, gc, bc);
|
|
this.hasTrans = true;
|
|
return;
|
|
}
|
|
|
|
byte r = ReadByteLittleEndian(alpha, 0);
|
|
byte g = ReadByteLittleEndian(alpha, 2);
|
|
byte b = ReadByteLittleEndian(alpha, 4);
|
|
this.rgb24Trans = new Rgb24(r, g, b);
|
|
this.hasTrans = true;
|
|
}
|
|
}
|
|
else if (this.pngColorType == PngColorType.Grayscale)
|
|
{
|
|
if (alpha.Length >= 2)
|
|
{
|
|
if (this.header.BitDepth == 16)
|
|
{
|
|
this.luminance16Trans = BinaryPrimitives.ReadUInt16LittleEndian(alpha.Slice(0, 2));
|
|
}
|
|
else
|
|
{
|
|
this.luminanceTrans = ReadByteLittleEndian(alpha, 0);
|
|
}
|
|
|
|
this.hasTrans = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Processes a scanline that uses a palette
|
|
/// </summary>
|
|
/// <typeparam name="TPixel">The type of pixel we are expanding to</typeparam>
|
|
/// <param name="scanline">The defiltered scanline</param>
|
|
/// <param name="row">The current output image row</param>
|
|
private void ProcessScanlineFromPalette<TPixel>(ReadOnlySpan<byte> scanline, Span<TPixel> row)
|
|
where TPixel : struct, IPixel<TPixel>
|
|
{
|
|
ReadOnlySpan<Rgb24> palettePixels = MemoryMarshal.Cast<byte, Rgb24>(this.palette);
|
|
var color = default(TPixel);
|
|
|
|
if (this.paletteAlpha?.Length > 0)
|
|
{
|
|
Rgba32 rgba = default;
|
|
|
|
// If the alpha palette is not null and has one or more entries, this means, that the image contains an alpha
|
|
// channel and we should try to read it.
|
|
for (int x = 0; x < this.header.Width; x++)
|
|
{
|
|
int index = scanline[x];
|
|
rgba.A = this.paletteAlpha.Length > index ? this.paletteAlpha[index] : byte.MaxValue;
|
|
rgba.Rgb = palettePixels[index];
|
|
|
|
color.PackFromRgba32(rgba);
|
|
row[x] = color;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
// TODO: We should have PackFromRgb24.
|
|
var rgba = new Rgba32(0, 0, 0, byte.MaxValue);
|
|
for (int x = 0; x < this.header.Width; x++)
|
|
{
|
|
int index = scanline[x];
|
|
|
|
rgba.Rgb = palettePixels[index];
|
|
|
|
color.PackFromRgba32(rgba);
|
|
row[x] = color;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads a header chunk from the data.
|
|
/// </summary>
|
|
/// <param name="data">The <see cref="T:ReadOnlySpan{byte}"/> containing data.</param>
|
|
private void ReadHeaderChunk(ReadOnlySpan<byte> data)
|
|
{
|
|
this.header = new PngHeader(
|
|
width: BinaryPrimitives.ReadInt32BigEndian(data.Slice(0, 4)),
|
|
height: BinaryPrimitives.ReadInt32BigEndian(data.Slice(4, 4)),
|
|
bitDepth: data[8],
|
|
colorType: (PngColorType)data[9],
|
|
compressionMethod: data[10],
|
|
filterMethod: data[11],
|
|
interlaceMethod: (PngInterlaceMode)data[12]);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Validates the png header.
|
|
/// </summary>
|
|
/// <exception cref="NotSupportedException">
|
|
/// Thrown if the image does pass validation.
|
|
/// </exception>
|
|
private void ValidateHeader()
|
|
{
|
|
if (!ColorTypes.ContainsKey(this.header.ColorType))
|
|
{
|
|
throw new NotSupportedException("Color type is not supported or not valid.");
|
|
}
|
|
|
|
if (!ColorTypes[this.header.ColorType].Contains(this.header.BitDepth))
|
|
{
|
|
throw new NotSupportedException("Bit depth is not supported or not valid.");
|
|
}
|
|
|
|
if (this.header.FilterMethod != 0)
|
|
{
|
|
throw new NotSupportedException("The png specification only defines 0 as filter method.");
|
|
}
|
|
|
|
if (this.header.InterlaceMethod != PngInterlaceMode.None && this.header.InterlaceMethod != PngInterlaceMode.Adam7)
|
|
{
|
|
throw new NotSupportedException("The png specification only defines 'None' and 'Adam7' as interlaced methods.");
|
|
}
|
|
|
|
this.pngColorType = this.header.ColorType;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads a text chunk containing image properties from the data.
|
|
/// </summary>
|
|
/// <param name="metadata">The metadata to decode to.</param>
|
|
/// <param name="data">The <see cref="T:byte[]"/> containing data.</param>
|
|
/// <param name="length">The maximum length to read.</param>
|
|
private void ReadTextChunk(ImageMetaData metadata, byte[] data, int length)
|
|
{
|
|
if (this.ignoreMetadata)
|
|
{
|
|
return;
|
|
}
|
|
|
|
int zeroIndex = 0;
|
|
|
|
for (int i = 0; i < length; i++)
|
|
{
|
|
if (data[i] == 0)
|
|
{
|
|
zeroIndex = i;
|
|
break;
|
|
}
|
|
}
|
|
|
|
string name = this.textEncoding.GetString(data, 0, zeroIndex);
|
|
string value = this.textEncoding.GetString(data, zeroIndex + 1, length - zeroIndex - 1);
|
|
|
|
metadata.Properties.Add(new ImageProperty(name, value));
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads a chunk from the stream.
|
|
/// </summary>
|
|
/// <param name="chunk">The image format chunk.</param>
|
|
/// <returns>
|
|
/// The <see cref="PngChunk"/>.
|
|
/// </returns>
|
|
private bool TryReadChunk(out PngChunk chunk)
|
|
{
|
|
int length = this.ReadChunkLength();
|
|
|
|
if (length == -1)
|
|
{
|
|
chunk = default;
|
|
|
|
// IEND
|
|
return false;
|
|
}
|
|
|
|
while (length < 0 || length > (this.currentStream.Length - this.currentStream.Position))
|
|
{
|
|
// Not a valid chunk so we skip back all but one of the four bytes we have just read.
|
|
// That lets us read one byte at a time until we reach a known chunk.
|
|
this.currentStream.Position -= 3;
|
|
|
|
length = this.ReadChunkLength();
|
|
|
|
if (length == -1)
|
|
{
|
|
chunk = default;
|
|
|
|
return false;
|
|
}
|
|
}
|
|
|
|
PngChunkType type = this.ReadChunkType();
|
|
|
|
// NOTE: Reading the chunk data is the responsible of the caller
|
|
if (type == PngChunkType.Data)
|
|
{
|
|
chunk = new PngChunk(length, type);
|
|
|
|
return true;
|
|
}
|
|
|
|
chunk = new PngChunk(
|
|
length: length,
|
|
type: type,
|
|
data: this.ReadChunkData(length),
|
|
crc: this.ReadChunkCrc());
|
|
|
|
if (chunk.IsCritical)
|
|
{
|
|
this.ValidateChunk(chunk);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Validates the png chunk.
|
|
/// </summary>
|
|
/// <param name="chunk">The <see cref="PngChunk"/>.</param>
|
|
private void ValidateChunk(in PngChunk chunk)
|
|
{
|
|
this.crc.Reset();
|
|
this.crc.Update(this.chunkTypeBuffer);
|
|
this.crc.Update(chunk.Data.GetSpan());
|
|
|
|
if (this.crc.Value != chunk.Crc)
|
|
{
|
|
string chunkTypeName = Encoding.UTF8.GetString(this.chunkTypeBuffer, 0, 4);
|
|
|
|
throw new ImageFormatException($"CRC Error. PNG {chunkTypeName} chunk is corrupt!");
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the cycle redundancy chunk from the data.
|
|
/// </summary>
|
|
/// <exception cref="ImageFormatException">
|
|
/// Thrown if the input stream is not valid or corrupt.
|
|
/// </exception>
|
|
private uint ReadChunkCrc()
|
|
{
|
|
int numBytes = this.currentStream.Read(this.crcBuffer, 0, 4);
|
|
|
|
if (numBytes >= 1 && numBytes <= 3)
|
|
{
|
|
throw new ImageFormatException("Image stream is not valid!");
|
|
}
|
|
|
|
return BinaryPrimitives.ReadUInt32BigEndian(this.crcBuffer);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Skips the chunk data and the cycle redundancy chunk read from the data.
|
|
/// </summary>
|
|
/// <param name="chunk">The image format chunk.</param>
|
|
private void SkipChunkDataAndCrc(in PngChunk chunk)
|
|
{
|
|
this.currentStream.Skip(chunk.Length);
|
|
this.currentStream.Skip(4);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Reads the chunk data from the stream.
|
|
/// </summary>
|
|
/// <param name="length">The length of the chunk data to read.</param>
|
|
private IManagedByteBuffer ReadChunkData(int length)
|
|
{
|
|
// We rent the buffer here to return it afterwards in Decode()
|
|
IManagedByteBuffer buffer = this.configuration.MemoryAllocator.AllocateManagedByteBuffer(length, AllocationOptions.Clean);
|
|
|
|
this.currentStream.Read(buffer.Array, 0, length);
|
|
|
|
return buffer;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Identifies the chunk type from the chunk.
|
|
/// </summary>
|
|
/// <exception cref="ImageFormatException">
|
|
/// Thrown if the input stream is not valid.
|
|
/// </exception>
|
|
private PngChunkType ReadChunkType()
|
|
{
|
|
int numBytes = this.currentStream.Read(this.chunkTypeBuffer, 0, 4);
|
|
|
|
if (numBytes >= 1 && numBytes <= 3)
|
|
{
|
|
throw new ImageFormatException("Image stream is not valid!");
|
|
}
|
|
|
|
return (PngChunkType)BinaryPrimitives.ReadUInt32BigEndian(this.chunkTypeBuffer.AsSpan());
|
|
}
|
|
|
|
/// <summary>
|
|
/// Calculates the length of the given chunk.
|
|
/// </summary>
|
|
/// <exception cref="ImageFormatException">
|
|
/// Thrown if the input stream is not valid.
|
|
/// </exception>
|
|
private int ReadChunkLength()
|
|
{
|
|
int numBytes = this.currentStream.Read(this.chunkLengthBuffer, 0, 4);
|
|
|
|
if (numBytes < 4)
|
|
{
|
|
return -1;
|
|
}
|
|
|
|
return BinaryPrimitives.ReadInt32BigEndian(this.chunkLengthBuffer);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Returns the correct number of columns for each interlaced pass.
|
|
/// </summary>
|
|
/// <param name="passIndex">Th current pass index</param>
|
|
/// <returns>The <see cref="int"/></returns>
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
private int ComputeColumnsAdam7(int passIndex)
|
|
{
|
|
int width = this.header.Width;
|
|
switch (passIndex)
|
|
{
|
|
case 0: return (width + 7) / 8;
|
|
case 1: return (width + 3) / 8;
|
|
case 2: return (width + 3) / 4;
|
|
case 3: return (width + 1) / 4;
|
|
case 4: return (width + 1) / 2;
|
|
case 5: return width / 2;
|
|
case 6: return width;
|
|
default: throw new ArgumentException($"Not a valid pass index: {passIndex}");
|
|
}
|
|
}
|
|
|
|
private void SwapBuffers()
|
|
{
|
|
IManagedByteBuffer temp = this.previousScanline;
|
|
this.previousScanline = this.scanline;
|
|
this.scanline = temp;
|
|
}
|
|
}
|
|
}
|