/// <inheritdoc/>
public void Dispose()
{
this.InputStream?.Dispose();
this.Frame?.Dispose();
this.fastACTables?.Dispose();
// Set large fields to null.
this.InputStream = null;
this.Frame = null;
this.dcHuffmanTables = null;
this.acHuffmanTables = null;
this.fastACTables = null;
}
/// <summary>
/// Parses the input stream for file markers
/// </summary>
/// <param name="stream">The input stream</param>
/// <param name="metadataOnly">Whether to decode metadata only.</param>
public void ParseStream(Stream stream, bool metadataOnly = false)
{
this.MetaData = new ImageMetaData();
this.InputStream = new DoubleBufferedStreamReader(this.configuration.MemoryAllocator, stream);
// Check for the Start Of Image marker.
this.InputStream.Read(this.markerBuffer, 0, 2);
var fileMarker = new JpegFileMarker(this.markerBuffer[1], 0);
if (fileMarker.Marker != JpegConstants.Markers.SOI)
{
throw new ImageFormatException("Missing SOI marker.");
}
this.InputStream.Read(this.markerBuffer, 0, 2);
byte marker = this.markerBuffer[1];
fileMarker = new JpegFileMarker(marker, (int)this.InputStream.Position - 2);
this.QuantizationTables = new Block8x8F[4];
// Only assign what we need
if (!metadataOnly)
{
this.dcHuffmanTables = new HuffmanTables();
this.acHuffmanTables = new HuffmanTables();
this.fastACTables = new FastACTables(this.configuration.MemoryAllocator);
}
// 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))
{
if (!fileMarker.Invalid)
{
// Get the marker length
int remaining = this.ReadUint16() - 2;
switch (fileMarker.Marker)
{
case JpegConstants.Markers.SOF0:
case JpegConstants.Markers.SOF1:
case JpegConstants.Markers.SOF2:
this.ProcessStartOfFrameMarker(remaining, fileMarker, metadataOnly);
break;
case JpegConstants.Markers.SOS:
if (!metadataOnly)
{
this.ProcessStartOfScanMarker();
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)
{
this.InputStream.Skip(remaining);
}
else
{
this.ProcessDefineHuffmanTablesMarker(remaining);
}
break;
case JpegConstants.Markers.DQT:
this.ProcessDefineQuantizationTablesMarker(remaining);
break;
case JpegConstants.Markers.DRI:
if (metadataOnly)
{
this.InputStream.Skip(remaining);
}
else
{
this.ProcessDefineRestartIntervalMarker(remaining);
}
break;
case JpegConstants.Markers.APP0:
this.ProcessApplicationHeaderMarker(remaining);
break;
case JpegConstants.Markers.APP1:
this.ProcessApp1Marker(remaining);
break;
case JpegConstants.Markers.APP2:
this.ProcessApp2Marker(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:
case JpegConstants.Markers.APP13:
this.InputStream.Skip(remaining);
break;
case JpegConstants.Markers.APP14:
this.ProcessApp14Marker(remaining);
break;
case JpegConstants.Markers.APP15:
case JpegConstants.Markers.COM:
this.InputStream.Skip(remaining);
break;
}
}
// Read on.
fileMarker = FindNextFileMarker(this.markerBuffer, this.InputStream);
}
}
