@ -7,6 +7,7 @@ using System.IO;
using System.Runtime.InteropServices ;
using SixLabors.ImageSharp.Formats.Experimental.Tiff.Compression ;
using SixLabors.ImageSharp.Formats.Gif ;
using SixLabors.ImageSharp.Formats.Png ;
using SixLabors.ImageSharp.Formats.Png.Zlib ;
using SixLabors.ImageSharp.Memory ;
@ -149,6 +150,11 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff.Utils
return this . WriteDeflateCompressedRgb ( image , rowSpan , useHorizontalPredictor ) ;
}
if ( compression = = TiffEncoderCompression . Lzw )
{
return this . WriteLzwCompressedRgb ( image , rowSpan , useHorizontalPredictor ) ;
}
if ( compression = = TiffEncoderCompression . PackBits )
{
return this . WriteRgbPackBitsCompressed ( image , rowSpan ) ;
@ -205,6 +211,44 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff.Utils
return bytesWritten ;
}
/// <summary>
/// Writes the image data as RGB compressed with lzw to the stream.
/// </summary>
/// <typeparam name="TPixel">The pixel data.</typeparam>
/// <param name="image">The image to write to the stream.</param>
/// <param name="rowSpan">A Span for a pixel row.</param>
/// <param name="useHorizontalPredictor">Indicates if horizontal prediction should be used. Should only be used with deflate compression.</param>
/// <returns>The number of bytes written.</returns>
private int WriteLzwCompressedRgb < TPixel > ( Image < TPixel > image , Span < byte > rowSpan , bool useHorizontalPredictor )
where TPixel : unmanaged , IPixel < TPixel >
{
int bytesWritten = 0 ;
using var memoryStream = new MemoryStream ( ) ;
IMemoryOwner < byte > pixelData = this . memoryAllocator . Allocate < byte > ( image . Width * image . Height * 3 ) ;
Span < byte > pixels = pixelData . GetSpan ( ) ;
for ( int y = 0 ; y < image . Height ; y + + )
{
Span < TPixel > pixelRow = image . GetPixelRowSpan ( y ) ;
PixelOperations < TPixel > . Instance . ToRgb24Bytes ( this . configuration , pixelRow , rowSpan , pixelRow . Length ) ;
if ( useHorizontalPredictor )
{
this . ApplyHorizontalPredictionRgb ( rowSpan ) ;
}
rowSpan . CopyTo ( pixels . Slice ( y * image . Width * 3 ) ) ;
}
using var lzwEncoder = new TiffLzwEncoder ( pixelData , 8 ) ;
lzwEncoder . Encode ( memoryStream ) ;
byte [ ] buffer = memoryStream . ToArray ( ) ;
this . output . Write ( buffer ) ;
bytesWritten + = buffer . Length ;
return bytesWritten ;
}
/// <summary>
/// Applies a horizontal predictor to the rgb row.
/// Make use of the fact that many continuous-tone images rarely vary much in pixel value from one pixel to the next.
@ -425,7 +469,7 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff.Utils
/// <param name="image">The image to write to the stream.</param>
/// <param name="padding">The padding bytes for each row.</param>
/// <param name="compression">The compression to use.</param>
/// <param name="useHorizontalPredictor">Indicates if horizontal prediction should be used. Should only be used with deflate compression.</param>
/// <param name="useHorizontalPredictor">Indicates if horizontal prediction should be used. Should only be used with deflate or lzw compression.</param>
/// <returns>The number of bytes written.</returns>
public int WriteGray < TPixel > ( Image < TPixel > image , int padding , TiffEncoderCompression compression , bool useHorizontalPredictor )
where TPixel : unmanaged , IPixel < TPixel >
@ -438,6 +482,11 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff.Utils
return this . WriteGrayDeflateCompressed ( image , rowSpan , useHorizontalPredictor ) ;
}
if ( compression = = TiffEncoderCompression . Lzw )
{
return this . WriteGrayLzwCompressed ( image , rowSpan , useHorizontalPredictor ) ;
}
if ( compression = = TiffEncoderCompression . PackBits )
{
return this . WriteGrayPackBitsCompressed ( image , rowSpan ) ;
@ -460,7 +509,7 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff.Utils
/// </summary>
/// <param name="image">The image to write to the stream.</param>
/// <param name="rowSpan">A span of a row of pixels.</param>
/// <param name="useHorizontalPredictor">Indicates if horizontal prediction should be used. Should only be used with deflate compression. </param>
/// <param name="useHorizontalPredictor">Indicates if horizontal prediction should be used.</param>
/// <returns>The number of bytes written.</returns>
private int WriteGrayDeflateCompressed < TPixel > ( Image < TPixel > image , Span < byte > rowSpan , bool useHorizontalPredictor )
where TPixel : unmanaged , IPixel < TPixel >
@ -492,6 +541,42 @@ namespace SixLabors.ImageSharp.Formats.Experimental.Tiff.Utils
return bytesWritten ;
}
/// <summary>
/// Writes the image data as 8 bit gray with lzw compression to the stream.
/// </summary>
/// <param name="image">The image to write to the stream.</param>
/// <param name="rowSpan">A span of a row of pixels.</param>
/// <param name="useHorizontalPredictor">Indicates if horizontal prediction should be used.</param>
/// <returns>The number of bytes written.</returns>
private int WriteGrayLzwCompressed < TPixel > ( Image < TPixel > image , Span < byte > rowSpan , bool useHorizontalPredictor )
where TPixel : unmanaged , IPixel < TPixel >
{
int bytesWritten = 0 ;
using var memoryStream = new MemoryStream ( ) ;
IMemoryOwner < byte > pixelData = this . memoryAllocator . Allocate < byte > ( image . Width * image . Height ) ;
Span < byte > pixels = pixelData . GetSpan ( ) ;
for ( int y = 0 ; y < image . Height ; y + + )
{
Span < TPixel > pixelRow = image . GetPixelRowSpan ( y ) ;
PixelOperations < TPixel > . Instance . ToL8Bytes ( this . configuration , pixelRow , rowSpan , pixelRow . Length ) ;
if ( useHorizontalPredictor )
{
this . ApplyHorizontalPredictionGray ( rowSpan ) ;
}
rowSpan . CopyTo ( pixels . Slice ( y * image . Width ) ) ;
}
using var lzwEncoder = new TiffLzwEncoder ( pixelData , 8 ) ;
lzwEncoder . Encode ( memoryStream ) ;
byte [ ] buffer = memoryStream . ToArray ( ) ;
this . output . Write ( buffer ) ;
bytesWritten + = buffer . Length ;
return bytesWritten ;
}
/// <summary>
/// Applies a horizontal predictor to a gray pixel row.
/// </summary>
Brian Popow
6 years ago