@ -3,6 +3,7 @@
using System ;
using System.Buffers ;
using System.Collections.Generic ;
using System.IO ;
using System.Runtime.CompilerServices ;
using System.Runtime.InteropServices ;
@ -22,19 +23,24 @@ namespace SixLabors.ImageSharp.Formats.Gif
internal sealed class GifDecoderCore : IImageDecoderInternals
{
/// <summary>
/// The temp buffer used to reduce allocations .
/// The temp buffer.
/// </summary>
private readonly byte [ ] buffer = new byte [ 1 6 ] ;
private byte [ ] buffer = new byte [ 1 6 ] ;
/// <summary>
/// The currently loaded stream .
/// The global color table .
/// </summary>
private BufferedReadStream stream ;
private IMemoryOwner < byte > globalColorTable ;
/// <summary>
/// The glob al color table.
/// The current loc al color table.
/// </summary>
private IMemoryOwner < byte > globalColorTable ;
private IMemoryOwner < byte > currentLocalColorTable ;
/// <summary>
/// Gets the size in bytes of the current local color table.
/// </summary>
private int currentLocalColorTableSize ;
/// <summary>
/// The area to restore.
@ -56,6 +62,26 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// </summary>
private GifImageDescriptor imageDescriptor ;
/// <summary>
/// The global configuration.
/// </summary>
private readonly Configuration configuration ;
/// <summary>
/// Used for allocating memory during processing operations.
/// </summary>
private readonly MemoryAllocator memoryAllocator ;
/// <summary>
/// The maximum number of frames to decode. Inclusive.
/// </summary>
private readonly uint maxFrames ;
/// <summary>
/// Whether to skip metadata during decode.
/// </summary>
private readonly bool skipMetadata ;
/// <summary>
/// The abstract metadata.
/// </summary>
@ -73,23 +99,14 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// <param name="options">The decoder options.</param>
public GifDecoderCore ( Configuration configuration , IGifDecoderOptions options )
{
this . IgnoreMetadata = options . IgnoreMetadata ;
this . DecodingMode = options . DecodingMode ;
this . Configuration = configuration ? ? Configuration . Default ;
this . skipMetadata = options . IgnoreMetadata ;
this . configuration = configuration ? ? Configuration . Default ;
this . maxFrames = options . DecodingMode = = FrameDecodingMode . All ? options . MaxFrames : 1 ;
this . memoryAllocator = this . configuration . MemoryAllocator ;
}
/// <inheritdoc />
public Configuration Configuration { get ; }
/// <summary>
/// Gets or sets a value indicating whether the metadata should be ignored when the image is being decoded.
/// </summary>
public bool IgnoreMetadata { get ; internal set ; }
/// <summary>
/// Gets the decoding mode for multi-frame images.
/// </summary>
public FrameDecodingMode DecodingMode { get ; }
public Configuration Configuration = > this . configuration ;
/// <summary>
/// Gets the dimensions of the image.
@ -102,6 +119,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
public Image < TPixel > Decode < TPixel > ( BufferedReadStream stream , CancellationToken cancellationToken )
where TPixel : unmanaged , IPixel < TPixel >
{
uint frameCount = 0 ;
Image < TPixel > image = null ;
ImageFrame < TPixel > previousFrame = null ;
try
@ -114,28 +132,32 @@ namespace SixLabors.ImageSharp.Formats.Gif
{
if ( nextFlag = = GifConstants . ImageLabel )
{
if ( previousFrame ! = null & & this . DecodingMode = = FrameDecodingMode . First )
if ( previousFrame ! = null & & + + frameCount = = this . maxFrames )
{
break ;
}
this . ReadFrame ( ref image , ref previousFrame ) ;
this . ReadFrame ( stream , ref image , ref previousFrame ) ;
// Reset per-frame state.
this . imageDescriptor = default ;
this . graphicsControlExtension = default ;
}
else if ( nextFlag = = GifConstants . ExtensionIntroducer )
{
switch ( stream . ReadByte ( ) )
{
case GifConstants . GraphicControlLabel :
this . ReadGraphicalControlExtension ( ) ;
this . ReadGraphicalControlExtension ( stream ) ;
break ;
case GifConstants . CommentLabel :
this . ReadComments ( ) ;
this . ReadComments ( stream ) ;
break ;
case GifConstants . ApplicationExtensionLabel :
this . ReadApplicationExtension ( ) ;
this . ReadApplicationExtension ( stream ) ;
break ;
case GifConstants . PlainTextLabel :
this . SkipBlock ( ) ; // Not supported by any known decoder.
SkipBlock ( stream ) ; // Not supported by any known decoder.
break ;
}
}
@ -154,6 +176,12 @@ namespace SixLabors.ImageSharp.Formats.Gif
finally
{
this . globalColorTable ? . Dispose ( ) ;
this . currentLocalColorTable ? . Dispose ( ) ;
}
if ( image is null )
{
GifThrowHelper . ThrowInvalidImageContentException ( "No data" ) ;
}
return image ;
@ -162,6 +190,9 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// <inheritdoc />
public IImageInfo Identify ( BufferedReadStream stream , CancellationToken cancellationToken )
{
uint frameCount = 0 ;
ImageFrameMetadata ? previousFrame = null ;
List < ImageFrameMetadata > framesMetadata = new ( ) ;
try
{
this . ReadLogicalScreenDescriptorAndGlobalColorTable ( stream ) ;
@ -172,23 +203,32 @@ namespace SixLabors.ImageSharp.Formats.Gif
{
if ( nextFlag = = GifConstants . ImageLabel )
{
this . ReadImageDescriptor ( ) ;
if ( previousFrame ! = null & & + + frameCount = = this . maxFrames )
{
break ;
}
this . ReadFrameMetadata ( stream , framesMetadata , ref previousFrame ) ;
// Reset per-frame state.
this . imageDescriptor = default ;
this . graphicsControlExtension = default ;
}
else if ( nextFlag = = GifConstants . ExtensionIntroducer )
{
switch ( stream . ReadByte ( ) )
{
case GifConstants . GraphicControlLabel :
this . SkipBlock ( ) ; // Skip graphic control extension block
this . ReadGraphicalControlExtension ( stream ) ;
break ;
case GifConstants . CommentLabel :
this . ReadComments ( ) ;
this . ReadComments ( stream ) ;
break ;
case GifConstants . ApplicationExtensionLabel :
this . ReadApplicationExtension ( ) ;
this . ReadApplicationExtension ( stream ) ;
break ;
case GifConstants . PlainTextLabel :
this . SkipBlock ( ) ; // Not supported by any known decoder.
SkipBlock ( stream ) ; // Not supported by any known decoder.
break ;
}
}
@ -207,6 +247,12 @@ namespace SixLabors.ImageSharp.Formats.Gif
finally
{
this . globalColorTable ? . Dispose ( ) ;
this . currentLocalColorTable ? . Dispose ( ) ;
}
if ( this . logicalScreenDescriptor . Width = = 0 & & this . logicalScreenDescriptor . Height = = 0 )
{
GifThrowHelper . ThrowNoHeader ( ) ;
}
return new ImageInfo (
@ -219,9 +265,10 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// <summary>
/// Reads the graphic control extension.
/// </summary>
private void ReadGraphicalControlExtension ( )
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
private void ReadGraphicalControlExtension ( BufferedReadStream stream )
{
int bytesRead = this . stream . Read ( this . buffer , 0 , 6 ) ;
int bytesRead = stream . Read ( this . buffer , 0 , 6 ) ;
if ( bytesRead ! = 6 )
{
GifThrowHelper . ThrowInvalidImageContentException ( "Not enough data to read the graphic control extension" ) ;
@ -233,9 +280,10 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// <summary>
/// Reads the image descriptor.
/// </summary>
private void ReadImageDescriptor ( )
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
private void ReadImageDescriptor ( BufferedReadStream stream )
{
int bytesRead = this . stream . Read ( this . buffer , 0 , 9 ) ;
int bytesRead = stream . Read ( this . buffer , 0 , 9 ) ;
if ( bytesRead ! = 9 )
{
GifThrowHelper . ThrowInvalidImageContentException ( "Not enough data to read the image descriptor" ) ;
@ -251,9 +299,10 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// <summary>
/// Reads the logical screen descriptor.
/// </summary>
private void ReadLogicalScreenDescriptor ( )
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
private void ReadLogicalScreenDescriptor ( BufferedReadStream stream )
{
int bytesRead = this . stream . Read ( this . buffer , 0 , 7 ) ;
int bytesRead = stream . Read ( this . buffer , 0 , 7 ) ;
if ( bytesRead ! = 7 )
{
GifThrowHelper . ThrowInvalidImageContentException ( "Not enough data to read the logical screen descriptor" ) ;
@ -266,103 +315,110 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// Reads the application extension block parsing any animation or XMP information
/// if present.
/// </summary>
private void ReadApplicationExtension ( )
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
private void ReadApplicationExtension ( BufferedReadStream stream )
{
int appLength = this . stream . ReadByte ( ) ;
int appLength = stream . ReadByte ( ) ;
// If the length is 11 then it's a valid extension and most likely
// a NETSCAPE, XMP or ANIMEXTS extension. We want the loop count from this.
long position = stream . Position ;
if ( appLength = = GifConstants . ApplicationBlockSize )
{
this . stream . Read ( this . buffer , 0 , GifConstants . ApplicationBlockSize ) ;
stream . Read ( this . buffer , 0 , GifConstants . ApplicationBlockSize ) ;
bool isXmp = this . buffer . AsSpan ( ) . StartsWith ( GifConstants . XmpApplicationIdentificationBytes ) ;
if ( isXmp & & ! this . IgnoreMetadata )
if ( isXmp & & ! this . skipMetadata )
{
var extension = GifXmpApplicationExtension . Read ( this . stream , this . M emoryAllocator) ;
GifXmpApplicationExtension extension = GifXmpApplicationExtension . Read ( stream , this . m emoryAllocator) ;
if ( extension . Data . Length > 0 )
{
this . metadata . XmpProfile = new XmpProfile ( extension . Data ) ;
this . metadata ! . XmpProfile = new XmpProfile ( extension . Data ) ;
}
else
{
// Reset the stream position and continue.
stream . Position = position ;
SkipBlock ( stream , appLength ) ;
}
return ;
}
else
{
int subBlockSize = this . stream . ReadByte ( ) ;
// TODO: There's also a NETSCAPE buffer extension.
// http://www.vurdalakov.net/misc/gif/netscape-buffering-application-extension
if ( subBlockSize = = GifConstants . NetscapeLoopingSubBlockSize )
{
this . stream . Read ( this . buffer , 0 , GifConstants . NetscapeLoopingSubBlockSize ) ;
this . gifMetadata . RepeatCount = GifNetscapeLoopingApplicationExtension . Parse ( this . buffer . AsSpan ( 1 ) ) . RepeatCount ;
this . stream . Skip ( 1 ) ; // Skip the terminator.
return ;
}
int subBlockSize = stream . ReadByte ( ) ;
// Could be something else not supported yet.
// Skip the subblock and terminator.
this . SkipBlock ( subBlockSize ) ;
// TODO: There's also a NETSCAPE buffer extension.
// http://www.vurdalakov.net/misc/gif/netscape-buffering-application-extension
if ( subBlockSize = = GifConstants . NetscapeLoopingSubBlockSize )
{
stream . Read ( this . buffer , 0 , GifConstants . NetscapeLoopingSubBlockSize ) ;
this . gifMetadata ! . RepeatCount = GifNetscapeLoopingApplicationExtension . Parse ( this . buffer . AsSpan ( 1 ) ) . RepeatCount ;
stream . Skip ( 1 ) ; // Skip the terminator.
return ;
}
// Could be something else not supported yet.
// Skip the subblock and terminator.
SkipBlock ( stream , subBlockSize ) ;
return ;
}
this . SkipBlock ( appLength ) ; // Not supported by any known decoder.
SkipBlock ( stream , appLength ) ; // Not supported by any known decoder.
}
/// <summary>
/// Skips over a block or reads its terminator.
/// <param name="blockSize">The length of the block to skip.</param>
/// </summary>
private void SkipBlock ( int blockSize = 0 )
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
/// <param name="blockSize">The length of the block to skip.</param>
private static void SkipBlock ( BufferedReadStream stream , int blockSize = 0 )
{
if ( blockSize > 0 )
{
this . stream . Skip ( blockSize ) ;
stream . Skip ( blockSize ) ;
}
int flag ;
while ( ( flag = this . stream . ReadByte ( ) ) > 0 )
while ( ( flag = stream . ReadByte ( ) ) > 0 )
{
this . stream . Skip ( flag ) ;
stream . Skip ( flag ) ;
}
}
/// <summary>
/// Reads the gif comments.
/// </summary>
private void ReadComments ( )
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
private void ReadComments ( BufferedReadStream stream )
{
int length ;
va rstringBuilder = new StringBuilder ( ) ;
while ( ( length = this . stream . ReadByte ( ) ) ! = 0 )
StringBuilde rstringBuilder = new ( ) ;
while ( ( length = stream . ReadByte ( ) ) ! = 0 )
{
if ( length > GifConstants . MaxCommentSubBlockLength )
{
GifThrowHelper . ThrowInvalidImageContentException ( $"Gif comment length '{length}' exceeds max '{GifConstants.MaxCommentSubBlockLength}' of a comment data block" ) ;
}
if ( this . Ignore Metadata)
if ( this . skip Metadata)
{
this . stream . Seek ( length , SeekOrigin . Current ) ;
stream . Seek ( length , SeekOrigin . Current ) ;
continue ;
}
using IMemoryOwner < byte > commentsBuffer = this . M emoryAllocator. Allocate < byte > ( length ) ;
using IMemoryOwner < byte > commentsBuffer = this . m emoryAllocator. Allocate < byte > ( length ) ;
Span < byte > commentsSpan = commentsBuffer . GetSpan ( ) ;
this . stream . Read ( commentsSpan ) ;
stream . Read ( commentsSpan ) ;
string commentPart = GifConstants . Encoding . GetString ( commentsSpan ) ;
stringBuilder . Append ( commentPart ) ;
}
if ( stringBuilder . Length > 0 )
{
this . gifMetadata . Comments . Add ( stringBuilder . ToString ( ) ) ;
this . gifMetadata ! . Comments . Add ( stringBuilder . ToString ( ) ) ;
}
}
@ -370,93 +426,77 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// Reads an individual gif frame.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
/// <param name="image">The image to decode the information to.</param>
/// <param name="previousFrame">The previous frame.</param>
private void ReadFrame < TPixel > ( ref Image < TPixel > image , ref ImageFrame < TPixel > previousFrame )
private void ReadFrame < TPixel > ( BufferedReadStream stream , ref Image < TPixel > ? image , ref ImageFrame < TPixel > ? previousFrame )
where TPixel : unmanaged , IPixel < TPixel >
{
this . ReadImageDescriptor ( ) ;
this . ReadImageDescriptor ( stream ) ;
IMemoryOwner < byte > localColorTable = null ;
Buffer2D < byte > indices = null ;
try
{
// Determine the color table for this frame. If there is a local one, use it otherwise use the global color table.
if ( this . imageDescriptor . LocalColorTableFlag )
{
int length = this . imageDescriptor . LocalColorTableSize * 3 ;
localColorTable = this . Configuration . MemoryAllocator . Allocate < byte > ( length , AllocationOptions . Clean ) ;
this . stream . Read ( localColorTable . GetSpan ( ) ) ;
}
// Determine the color table for this frame. If there is a local one, use it otherwise use the global color table.
bool hasLocalColorTable = this . imageDescriptor . LocalColorTableFlag ;
indices = this . Configuration . MemoryAllocator . Allocate2D < byte > ( this . imageDescriptor . Width , this . imageDescriptor . Height , AllocationOptions . Clean ) ;
this . ReadFrameIndices ( indices ) ;
Span < byte > rawColorTable = default ;
if ( localColorTable ! = null )
{
rawColorTable = localColorTable . GetSpan ( ) ;
}
else if ( this . globalColorTable ! = null )
{
rawColorTable = this . globalColorTable . GetSpan ( ) ;
}
ReadOnlySpan < Rgb24 > colorTable = MemoryMarshal . Cast < byte , Rgb24 > ( rawColorTable ) ;
this . ReadFrameColors ( ref image , ref previousFrame , indices , colorTable , this . imageDescriptor ) ;
if ( hasLocalColorTable )
{
// Read and store the local color table. We allocate the maximum possible size and slice to match.
int length = this . currentLocalColorTableSize = this . imageDescriptor . LocalColorTableSize * 3 ;
this . currentLocalColorTable ? ? = this . configuration . MemoryAllocator . Allocate < byte > ( 7 6 8 , AllocationOptions . Clean ) ;
stream . Read ( this . currentLocalColorTable . GetSpan ( ) . Slice ( 0 , length ) ) ;
}
// Skip any remaining blocks
this . SkipBlock ( ) ;
Span < byte > rawColorTable = default ;
if ( hasLocalColorTable )
{
rawColorTable = this . currentLocalColorTable ! . GetSpan ( ) . Slice ( 0 , this . currentLocalColorTableSize ) ;
}
finally
else if ( this . globalColorTable ! = null )
{
localColorTable ? . Dispose ( ) ;
indices ? . Dispose ( ) ;
rawColorTable = this . globalColorTable . GetSpan ( ) ;
}
}
/// <summary>
/// Reads the frame indices marking the color to use for each pixel.
/// </summary>
/// <param name="indices">The 2D pixel buffer to write to.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private void ReadFrameIndices ( Buffer2D < byte > indices )
{
int minCodeSize = this . stream . ReadByte ( ) ;
using var lzwDecoder = new LzwDecoder ( this . Configuration . MemoryAllocator , this . stream ) ;
lzwDecoder . DecodePixels ( minCodeSize , indices ) ;
ReadOnlySpan < Rgb24 > colorTable = MemoryMarshal . Cast < byte , Rgb24 > ( rawColorTable ) ;
this . ReadFrameColors ( stream , ref image , ref previousFrame , colorTable , this . imageDescriptor ) ;
// Skip any remaining blocks
SkipBlock ( stream ) ;
}
/// <summary>
/// Reads the frames colors, mapping indices to colors.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
/// <param name="image">The image to decode the information to.</param>
/// <param name="previousFrame">The previous frame.</param>
/// <param name="indices">The indexed pixels.</param>
/// <param name="colorTable">The color table containing the available colors.</param>
/// <param name="descriptor">The <see cref="GifImageDescriptor"/></param>
private void ReadFrameColors < TPixel > ( ref Image < TPixel > image , ref ImageFrame < TPixel > previousFrame , Buffer2D < byte > indices , ReadOnlySpan < Rgb24 > colorTable , in GifImageDescriptor descriptor )
private void ReadFrameColors < TPixel > (
BufferedReadStream stream ,
ref Image < TPixel > ? image ,
ref ImageFrame < TPixel > ? previousFrame ,
ReadOnlySpan < Rgb24 > colorTable ,
in GifImageDescriptor descriptor )
where TPixel : unmanaged , IPixel < TPixel >
{
int imageWidth = this . logicalScreenDescriptor . Width ;
int imageHeight = this . logicalScreenDescriptor . Height ;
bool transFlag = this . graphicsControlExtension . TransparencyFlag ;
ImageFrame < TPixel > prevFrame = null ;
ImageFrame < TPixel > currentFrame = null ;
ImageFrame < TPixel > ? prevFrame = null ;
ImageFrame < TPixel > ? currentFrame = null ;
ImageFrame < TPixel > imageFrame ;
if ( previousFrame is null )
{
if ( ! transFlag )
{
image = new Image < TPixel > ( this . C onfiguration, imageWidth , imageHeight , Color . Black . ToPixel < TPixel > ( ) , this . metadata ) ;
image = new Image < TPixel > ( this . c onfiguration, imageWidth , imageHeight , Color . Black . ToPixel < TPixel > ( ) , this . metadata ) ;
}
else
{
// This initializes the image to become fully transparent because the alpha channel is zero.
image = new Image < TPixel > ( this . C onfiguration, imageWidth , imageHeight , this . metadata ) ;
image = new Image < TPixel > ( this . c onfiguration, imageWidth , imageHeight , this . metadata ) ;
}
this . SetFrameMetadata ( image . Frames . RootFrame . Metadata ) ;
@ -470,7 +510,10 @@ namespace SixLabors.ImageSharp.Formats.Gif
prevFrame = previousFrame ;
}
currentFrame = image . Frames . AddFrame ( previousFrame ) ; // This clones the frame and adds it the collection
// We create a clone of the frame and add it.
// We will overpaint the difference of pixels on the current frame to create a complete image.
// This ensures that we have enough pixel data to process without distortion. #2450
currentFrame = image ! . Frames . AddFrame ( previousFrame ) ;
this . SetFrameMetadata ( currentFrame . Metadata ) ;
@ -494,64 +537,79 @@ namespace SixLabors.ImageSharp.Formats.Gif
byte transIndex = this . graphicsControlExtension . TransparencyIndex ;
int colorTableMaxIdx = colorTable . Length - 1 ;
for ( int y = descriptorTop ; y < descriptorBottom & & y < imageHeight ; y + + )
// For a properly encoded gif the descriptor dimensions will never exceed the logical screen dimensions.
// However we have images that exceed this that can be decoded by other libraries. #1530
using IMemoryOwner < byte > indicesRowOwner = this . memoryAllocator . Allocate < byte > ( descriptor . Width ) ;
Span < byte > indicesRow = indicesRowOwner . Memory . Span ;
ref byte indicesRowRef = ref MemoryMarshal . GetReference ( indicesRow ) ;
int minCodeSize = stream . ReadByte ( ) ;
if ( LzwDecoder . IsValidMinCodeSize ( minCodeSize ) )
{
ref byte indicesRowRef = ref MemoryMarshal . GetReference ( indices . DangerousGetRowSpan ( y - descriptorTop ) ) ;
using LzwDecoder lzwDecoder = new ( this . configuration . MemoryAllocator , stream , minCodeSize ) ;
// Check if this image is interlaced.
int writeY ; // the target y offset to write to
if ( descriptor . InterlaceFlag )
for ( int y = descriptorTop ; y < descriptorBottom & & y < imageHeight ; y + + )
{
// If so then we read lines at predetermined offsets.
// When an entire image height worth of offset lines has been read we consider this a pass.
// With each pass the number of offset lines changes and the starting line changes.
if ( interlaceY > = descriptor . Height )
// Check if this image is interlaced.
int writeY ; // the target y offset to write to
if ( descriptor . InterlaceFlag )
{
interlacePass + + ;
switch ( interlacePass )
// If so then we read lines at predetermined offsets.
// When an entire image height worth of offset lines has been read we consider this a pass.
// With each pass the number of offset lines changes and the starting line changes.
if ( interlaceY > = descriptor . Height )
{
case 1 :
interlaceY = 4 ;
break ;
case 2 :
interlaceY = 2 ;
interlaceIncrement = 4 ;
break ;
case 3 :
interlaceY = 1 ;
interlaceIncrement = 2 ;
break ;
interlacePass + + ;
switch ( interlacePass )
{
case 1 :
interlaceY = 4 ;
break ;
case 2 :
interlaceY = 2 ;
interlaceIncrement = 4 ;
break ;
case 3 :
interlaceY = 1 ;
interlaceIncrement = 2 ;
break ;
}
}
}
writeY = interlaceY + descriptor . Top ;
interlaceY + = interlaceIncrement ;
}
else
{
writeY = y ;
}
writeY = Math . Min ( interlaceY + descriptor . Top , image . Height ) ;
interlaceY + = interlaceIncrement ;
}
else
{
writeY = y ;
}
ref TPixel rowRef = ref MemoryMarshal . GetReference ( imageFrame . PixelBuffer . DangerousGetRowSpan ( writeY ) ) ;
lzwDecoder . DecodePixelRow ( indicesRow ) ;
ref TPixel rowRef = ref MemoryMarshal . GetReference ( imageFrame . PixelBuffer . DangerousGetRowSpan ( writeY ) ) ;
if ( ! transFlag )
{
// #403 The left + width value can be larger than the image width
for ( int x = descriptorLeft ; x < descriptorRight & & x < imageWidth ; x + + )
if ( ! transFlag )
{
int index = Numerics . Clamp ( Unsafe . Add ( ref indicesRowRef , x - descriptorLeft ) , 0 , colorTableMaxIdx ) ;
ref TPixel pixel = ref Unsafe . Add ( ref rowRef , x ) ;
Rgb24 rgb = colorTable [ index ] ;
pixel . FromRgb24 ( rgb ) ;
// #403 The left + width value can be larger than the image width
for ( int x = descriptorLeft ; x < descriptorRight & & x < imageWidth ; x + + )
{
int index = Numerics . Clamp ( Unsafe . Add ( ref indicesRowRef , x - descriptorLeft ) , 0 , colorTableMaxIdx ) ;
ref TPixel pixel = ref Unsafe . Add ( ref rowRef , x ) ;
Rgb24 rgb = colorTable [ index ] ;
pixel . FromRgb24 ( rgb ) ;
}
}
}
else
{
for ( int x = descriptorLeft ; x < descriptorRight & & x < imageWidth ; x + + )
else
{
int index = Numerics . Clamp ( Unsafe . Add ( ref indicesRowRef , x - descriptorLeft ) , 0 , colorTableMaxIdx ) ;
if ( transIndex ! = index )
for ( int x = descriptorLeft ; x < descriptorRight & & x < imageWidth ; x + + )
{
int index = Unsafe . Add ( ref indicesRowRef , x - descriptorLeft ) ;
// Treat any out of bounds values as transparent.
if ( index > colorTableMaxIdx | | index = = transIndex )
{
continue ;
}
ref TPixel pixel = ref Unsafe . Add ( ref rowRef , x ) ;
Rgb24 rgb = colorTable [ index ] ;
pixel . FromRgb24 ( rgb ) ;
@ -574,6 +632,43 @@ namespace SixLabors.ImageSharp.Formats.Gif
}
}
/// <summary>
/// Reads the frames metadata.
/// </summary>
/// <param name="stream">The <see cref="BufferedReadStream"/> containing image data.</param>
/// <param name="frameMetadata">The collection of frame metadata.</param>
/// <param name="previousFrame">The previous frame metadata.</param>
private void ReadFrameMetadata ( BufferedReadStream stream , List < ImageFrameMetadata > frameMetadata , ref ImageFrameMetadata ? previousFrame )
{
this . ReadImageDescriptor ( stream ) ;
// Skip the color table for this frame if local.
if ( this . imageDescriptor . LocalColorTableFlag )
{
// Read and store the local color table. We allocate the maximum possible size and slice to match.
int length = this . currentLocalColorTableSize = this . imageDescriptor . LocalColorTableSize * 3 ;
this . currentLocalColorTable ? ? = this . configuration . MemoryAllocator . Allocate < byte > ( 7 6 8 , AllocationOptions . Clean ) ;
stream . Read ( this . currentLocalColorTable . GetSpan ( ) . Slice ( 0 , length ) ) ;
}
// Skip the frame indices. Pixels length + mincode size.
// The gif format does not tell us the length of the compressed data beforehand.
int minCodeSize = stream . ReadByte ( ) ;
if ( LzwDecoder . IsValidMinCodeSize ( minCodeSize ) )
{
using LzwDecoder lzwDecoder = new ( this . configuration . MemoryAllocator , stream , minCodeSize ) ;
lzwDecoder . SkipIndices ( this . imageDescriptor . Width * this . imageDescriptor . Height ) ;
}
ImageFrameMetadata currentFrame = new ( ) ;
frameMetadata . Add ( currentFrame ) ;
this . SetFrameMetadata ( currentFrame ) ;
previousFrame = currentFrame ;
// Skip any remaining blocks
SkipBlock ( stream ) ;
}
/// <summary>
/// Restores the current frame area to the background.
/// </summary>
@ -587,7 +682,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
return ;
}
var interest = Rectangle . Intersect ( frame . Bounds ( ) , this . restoreArea . Value ) ;
Rectangle interest = Rectangle . Intersect ( frame . Bounds ( ) , this . restoreArea . Value ) ;
Buffer2DRegion < TPixel > pixelRegion = frame . PixelBuffer . GetRegion ( interest ) ;
pixelRegion . Clear ( ) ;
@ -595,7 +690,7 @@ namespace SixLabors.ImageSharp.Formats.Gif
}
/// <summary>
/// Sets the frames metadata.
/// Sets the metadata for the image frame .
/// </summary>
/// <param name="meta">The metadata.</param>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
@ -628,13 +723,11 @@ namespace SixLabors.ImageSharp.Formats.Gif
/// <param name="stream">The stream containing image data. </param>
private void ReadLogicalScreenDescriptorAndGlobalColorTable ( BufferedReadStream stream )
{
this . stream = stream ;
// Skip the identifier
this . stream . Skip ( 6 ) ;
this . ReadLogicalScreenDescriptor ( ) ;
stream . Skip ( 6 ) ;
this . ReadLogicalScreenDescriptor ( stream ) ;
var meta = new ImageMetadata ( ) ;
ImageMetadata meta = new ( ) ;
// The Pixel Aspect Ratio is defined to be the quotient of the pixel's
// width over its height. The value range in this field allows
@ -671,16 +764,26 @@ namespace SixLabors.ImageSharp.Formats.Gif
if ( this . logicalScreenDescriptor . GlobalColorTableFlag )
{
int globalColorTableLength = this . logicalScreenDescriptor . GlobalColorTableSize * 3 ;
this . gifMetadata . GlobalColorTableLength = globalColorTableLength ;
if ( globalColorTableLength > 0 )
{
this . globalColorTable = this . M emoryAllocator. Allocate < byte > ( globalColorTableLength , AllocationOptions . Clean ) ;
this . globalColorTable = this . m emoryAllocator. Allocate < byte > ( globalColorTableLength , AllocationOptions . Clean ) ;
// Read the global color table data from the stream
stream . Read ( this . globalColorTable . GetSpan ( ) ) ;
// Read the global color table data from the stream and preserve it in the gif metadata
Span < byte > globalColorTableSpan = this . globalColorTable . GetSpan ( ) ;
stream . Read ( globalColorTableSpan ) ;
//Color[] colorTable = new Color[this.logicalScreenDescriptor.GlobalColorTableSize];
//ReadOnlySpan<Rgb24> rgbTable = MemoryMarshal.Cast<byte, Rgb24>(globalColorTableSpan);
//for (int i = 0; i < colorTable.Length; i++)
//{
// colorTable[i] = new Color(rgbTable[i]);
//}
//this.gifMetadata.GlobalColorTable = colorTable;
}
}
//this.gifMetadata.BackgroundColorIndex = this.logicalScreenDescriptor.BackgroundColorIndex;
}
}
}
James Jackson-South
2 years ago
GitHub
