/// <inheritdoc/>
protected override void Decompress(BufferedReadStream stream, int byteCount, int stripHeight, Span <byte> buffer)
{
if (this.jpegTables != null)
{
using var jpegDecoder = new JpegDecoderCore(this.configuration, new JpegDecoder());
// TODO: Should we pass through the CancellationToken from the tiff decoder?
// If the PhotometricInterpretation is YCbCr we explicitly assume the JPEG data is in RGB color space.
// There seems no other way to determine that the JPEG data is RGB colorspace (no APP14 marker, componentId's are not RGB).
using SpectralConverter <Rgb24> spectralConverter = this.photometricInterpretation == TiffPhotometricInterpretation.YCbCr ?
new RgbJpegSpectralConverter <Rgb24>(this.configuration, CancellationToken.None) : new SpectralConverter <Rgb24>(this.configuration, CancellationToken.None);
var scanDecoder = new HuffmanScanDecoder(stream, spectralConverter, CancellationToken.None);
jpegDecoder.LoadTables(this.jpegTables, scanDecoder);
scanDecoder.ResetInterval = 0;
jpegDecoder.ParseStream(stream, scanDecoder, CancellationToken.None);
using var image = new Image <Rgb24>(this.configuration, spectralConverter.PixelBuffer, new ImageMetadata());
CopyImageBytesToBuffer(buffer, image);
}
else
{
using var image = Image.Load <Rgb24>(stream);
CopyImageBytesToBuffer(buffer, image);
}
}
/// <inheritdoc/>
public void Dispose()
{
this.Frame?.Dispose();
// Set large fields to null.
this.Frame = null;
this.scanDecoder = null;
}
/// <summary>
/// Load quantization and/or Huffman tables for subsequent use for jpeg's embedded in tiff's,
/// so those tables do not need to be duplicated with segmented tiff's (tiff's with multiple strips).
/// </summary>
/// <param name="tableBytes">The table bytes.</param>
/// <param name="huffmanScanDecoder">The scan decoder.</param>
public void LoadTables(byte[] tableBytes, HuffmanScanDecoder huffmanScanDecoder)
{
this.Metadata = new ImageMetadata();
this.QuantizationTables = new Block8x8F[4];
this.scanDecoder = huffmanScanDecoder;
using var ms = new MemoryStream(tableBytes);
using var stream = new BufferedReadStream(this.Configuration, ms);
// Check for the Start Of Image marker.
stream.Read(this.markerBuffer, 0, 2);
var fileMarker = new JpegFileMarker(this.markerBuffer[1], 0);
if (fileMarker.Marker != JpegConstants.Markers.SOI)
{
JpegThrowHelper.ThrowInvalidImageContentException("Missing SOI marker.");
}
// Read next marker.
stream.Read(this.markerBuffer, 0, 2);
byte marker = this.markerBuffer[1];
fileMarker = new JpegFileMarker(marker, (int)stream.Position - 2);
while (fileMarker.Marker != JpegConstants.Markers.EOI || (fileMarker.Marker == JpegConstants.Markers.EOI && fileMarker.Invalid))
{
if (!fileMarker.Invalid)
{
// Get the marker length.
int remaining = this.ReadUint16(stream) - 2;
switch (fileMarker.Marker)
{
case JpegConstants.Markers.SOI:
break;
case JpegConstants.Markers.RST0:
case JpegConstants.Markers.RST7:
break;
case JpegConstants.Markers.DHT:
this.ProcessDefineHuffmanTablesMarker(stream, remaining);
break;
case JpegConstants.Markers.DQT:
this.ProcessDefineQuantizationTablesMarker(stream, remaining);
break;
case JpegConstants.Markers.DRI:
this.ProcessDefineRestartIntervalMarker(stream, remaining);
break;
case JpegConstants.Markers.EOI:
return;
}
}
// Read next marker.
stream.Read(this.markerBuffer, 0, 2);
fileMarker = new JpegFileMarker(this.markerBuffer[1], 0);
}
}
/// <inheritdoc/>
public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
where TPixel : unmanaged, IPixel<TPixel>
{
using var spectralConverter = new SpectralConverter<TPixel>(this.Configuration, cancellationToken);
var scanDecoder = new HuffmanScanDecoder(stream, spectralConverter, cancellationToken);
this.ParseStream(stream, scanDecoder, cancellationToken);
this.InitExifProfile();
this.InitIccProfile();
this.InitIptcProfile();
this.InitDerivedMetadataProperties();
return new Image<TPixel>(this.Configuration, spectralConverter.PixelBuffer, this.Metadata);
}
/// <summary>
/// Parses the input stream for file markers.
/// </summary>
/// <param name="stream">The input stream.</param>
/// <param name="scanDecoder">Scan decoder used exclusively to decode SOS marker.</param>
/// <param name="cancellationToken">The token to monitor cancellation.</param>
internal void ParseStream(BufferedReadStream stream, HuffmanScanDecoder scanDecoder, CancellationToken cancellationToken)
{
bool metadataOnly = scanDecoder == null;
this.scanDecoder = scanDecoder;
this.Metadata = new ImageMetadata();
// Check for the Start Of Image marker.
stream.Read(this.markerBuffer, 0, 2);
var fileMarker = new JpegFileMarker(this.markerBuffer[1], 0);
if (fileMarker.Marker != JpegConstants.Markers.SOI)
{
JpegThrowHelper.ThrowInvalidImageContentException("Missing SOI marker.");
}
stream.Read(this.markerBuffer, 0, 2);
byte marker = this.markerBuffer[1];
fileMarker = new JpegFileMarker(marker, (int)stream.Position - 2);
this.QuantizationTables ??= new Block8x8F[4];
// Break only when we discover a valid EOI marker.
// https://github.com/SixLabors/ImageSharp/issues/695
while (fileMarker.Marker != JpegConstants.Markers.EOI
|| (fileMarker.Marker == JpegConstants.Markers.EOI && fileMarker.Invalid))
{
cancellationToken.ThrowIfCancellationRequested();
if (!fileMarker.Invalid)
{
// Get the marker length.
int remaining = this.ReadUint16(stream) - 2;
switch (fileMarker.Marker)
{
case JpegConstants.Markers.SOF0:
case JpegConstants.Markers.SOF1:
case JpegConstants.Markers.SOF2:
this.ProcessStartOfFrameMarker(stream, remaining, fileMarker, metadataOnly);
break;
case JpegConstants.Markers.SOF5:
JpegThrowHelper.ThrowNotSupportedException("Decoding jpeg files with differential sequential DCT is not supported.");
break;
case JpegConstants.Markers.SOF6:
JpegThrowHelper.ThrowNotSupportedException("Decoding jpeg files with differential progressive DCT is not supported.");
break;
case JpegConstants.Markers.SOF3:
case JpegConstants.Markers.SOF7:
JpegThrowHelper.ThrowNotSupportedException("Decoding lossless jpeg files is not supported.");
break;
case JpegConstants.Markers.SOF9:
case JpegConstants.Markers.SOF10:
case JpegConstants.Markers.SOF11:
case JpegConstants.Markers.SOF13:
case JpegConstants.Markers.SOF14:
case JpegConstants.Markers.SOF15:
JpegThrowHelper.ThrowNotSupportedException("Decoding jpeg files with arithmetic coding is not supported.");
break;
case JpegConstants.Markers.SOS:
if (!metadataOnly)
{
this.ProcessStartOfScanMarker(stream, remaining);
break;
}
else
{
// It's highly unlikely that APPn related data will be found after the SOS marker
// We should have gathered everything we need by now.
return;
}
case JpegConstants.Markers.DHT:
if (metadataOnly)
{
stream.Skip(remaining);
}
else
{
this.ProcessDefineHuffmanTablesMarker(stream, remaining);
}
break;
case JpegConstants.Markers.DQT:
this.ProcessDefineQuantizationTablesMarker(stream, remaining);
break;
case JpegConstants.Markers.DRI:
if (metadataOnly)
{
stream.Skip(remaining);
}
else
{
this.ProcessDefineRestartIntervalMarker(stream, remaining);
}
break;
case JpegConstants.Markers.APP0:
this.ProcessApplicationHeaderMarker(stream, remaining);
break;
case JpegConstants.Markers.APP1:
this.ProcessApp1Marker(stream, remaining);
break;
case JpegConstants.Markers.APP2:
this.ProcessApp2Marker(stream, remaining);
break;
case JpegConstants.Markers.APP3:
case JpegConstants.Markers.APP4:
case JpegConstants.Markers.APP5:
case JpegConstants.Markers.APP6:
case JpegConstants.Markers.APP7:
case JpegConstants.Markers.APP8:
case JpegConstants.Markers.APP9:
case JpegConstants.Markers.APP10:
case JpegConstants.Markers.APP11:
case JpegConstants.Markers.APP12:
stream.Skip(remaining);
break;
case JpegConstants.Markers.APP13:
this.ProcessApp13Marker(stream, remaining);
break;
case JpegConstants.Markers.APP14:
this.ProcessApp14Marker(stream, remaining);
break;
case JpegConstants.Markers.APP15:
case JpegConstants.Markers.COM:
stream.Skip(remaining);
break;
case JpegConstants.Markers.DAC:
JpegThrowHelper.ThrowNotSupportedException("Decoding jpeg files with arithmetic coding is not supported.");
break;
}
}
// Read on.
fileMarker = FindNextFileMarker(this.markerBuffer, stream);
}
}
