/// <summary>
/// Decodes the image data for chunky encoded pixel data.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="frame">The image frame to decode data into.</param>
/// <param name="rowsPerStrip">The rows per strip.</param>
/// <param name="stripOffsets">The strip offsets.</param>
/// <param name="stripByteCounts">The strip byte counts.</param>
/// <param name="cancellationToken">The token to monitor cancellation.</param>
private void DecodeStripsChunky <TPixel>(ImageFrame <TPixel> frame, int rowsPerStrip, Span <ulong> stripOffsets, Span <ulong> stripByteCounts, CancellationToken cancellationToken)
where TPixel : unmanaged, IPixel <TPixel>
{
// If the rowsPerStrip has the default value, which is effectively infinity. That is, the entire image is one strip.
if (rowsPerStrip == TiffConstants.RowsPerStripInfinity)
{
rowsPerStrip = frame.Height;
}
int uncompressedStripSize = this.CalculateStripBufferSize(frame.Width, rowsPerStrip);
int bitsPerPixel = this.BitsPerPixel;
using IMemoryOwner <byte> stripBuffer = this.memoryAllocator.Allocate <byte>(uncompressedStripSize, AllocationOptions.Clean);
Span <byte> stripBufferSpan = stripBuffer.GetSpan();
Buffer2D <TPixel> pixels = frame.PixelBuffer;
using TiffBaseDecompressor decompressor = TiffDecompressorsFactory.Create(
this.Configuration,
this.CompressionType,
this.memoryAllocator,
this.PhotometricInterpretation,
frame.Width,
bitsPerPixel,
this.ColorType,
this.Predictor,
this.FaxCompressionOptions,
this.JpegTables,
this.FillOrder,
this.byteOrder);
TiffBaseColorDecoder <TPixel> colorDecoder = TiffColorDecoderFactory <TPixel> .Create(
this.Configuration,
this.memoryAllocator,
this.ColorType,
this.BitsPerSample,
this.ColorMap,
this.ReferenceBlackAndWhite,
this.YcbcrCoefficients,
this.YcbcrSubSampling,
this.byteOrder);
for (int stripIndex = 0; stripIndex < stripOffsets.Length; stripIndex++)
{
cancellationToken.ThrowIfCancellationRequested();
int stripHeight = stripIndex < stripOffsets.Length - 1 || frame.Height % rowsPerStrip == 0
? rowsPerStrip
: frame.Height % rowsPerStrip;
int top = rowsPerStrip * stripIndex;
if (top + stripHeight > frame.Height)
{
// Make sure we ignore any strips that are not needed for the image (if too many are present).
break;
}
decompressor.Decompress(
this.inputStream,
stripOffsets[stripIndex],
stripByteCounts[stripIndex],
stripHeight,
stripBufferSpan);
colorDecoder.Decode(stripBufferSpan, pixels, 0, top, frame.Width, stripHeight);
}
}
/// <summary>
/// Decodes the image data for planar encoded pixel data.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="frame">The image frame to decode data into.</param>
/// <param name="rowsPerStrip">The number of rows per strip of data.</param>
/// <param name="stripOffsets">An array of byte offsets to each strip in the image.</param>
/// <param name="stripByteCounts">An array of the size of each strip (in bytes).</param>
/// <param name="cancellationToken">The token to monitor cancellation.</param>
private void DecodeStripsPlanar <TPixel>(ImageFrame <TPixel> frame, int rowsPerStrip, Span <ulong> stripOffsets, Span <ulong> stripByteCounts, CancellationToken cancellationToken)
where TPixel : unmanaged, IPixel <TPixel>
{
int stripsPerPixel = this.BitsPerSample.Channels;
int stripsPerPlane = stripOffsets.Length / stripsPerPixel;
int bitsPerPixel = this.BitsPerPixel;
Buffer2D <TPixel> pixels = frame.PixelBuffer;
var stripBuffers = new IMemoryOwner <byte> [stripsPerPixel];
try
{
for (int stripIndex = 0; stripIndex < stripBuffers.Length; stripIndex++)
{
int uncompressedStripSize = this.CalculateStripBufferSize(frame.Width, rowsPerStrip, stripIndex);
stripBuffers[stripIndex] = this.memoryAllocator.Allocate <byte>(uncompressedStripSize);
}
using TiffBaseDecompressor decompressor = TiffDecompressorsFactory.Create(
this.Configuration,
this.CompressionType,
this.memoryAllocator,
this.PhotometricInterpretation,
frame.Width,
bitsPerPixel,
this.ColorType,
this.Predictor,
this.FaxCompressionOptions,
this.JpegTables,
this.FillOrder,
this.byteOrder);
TiffBasePlanarColorDecoder <TPixel> colorDecoder = TiffColorDecoderFactory <TPixel> .CreatePlanar(
this.ColorType,
this.BitsPerSample,
this.ColorMap,
this.ReferenceBlackAndWhite,
this.YcbcrCoefficients,
this.YcbcrSubSampling,
this.byteOrder);
for (int i = 0; i < stripsPerPlane; i++)
{
cancellationToken.ThrowIfCancellationRequested();
int stripHeight = i < stripsPerPlane - 1 || frame.Height % rowsPerStrip == 0 ? rowsPerStrip : frame.Height % rowsPerStrip;
int stripIndex = i;
for (int planeIndex = 0; planeIndex < stripsPerPixel; planeIndex++)
{
decompressor.Decompress(
this.inputStream,
stripOffsets[stripIndex],
stripByteCounts[stripIndex],
stripHeight,
stripBuffers[planeIndex].GetSpan());
stripIndex += stripsPerPlane;
}
colorDecoder.Decode(stripBuffers, pixels, 0, rowsPerStrip * i, frame.Width, stripHeight);
}
}
finally
{
foreach (IMemoryOwner <byte> buf in stripBuffers)
{
buf?.Dispose();
}
}
}
