/// <inheritdoc />
public void Decompress(TiffDecompressionContext context, ReadOnlyMemory <byte> input, Memory <byte> output)
{
if (context is null)
{
throw new ArgumentNullException(nameof(context));
}
// Identify this block
JpegDecoder decoder = Interlocked.Exchange(ref _decoder, null) ?? LoadJpegDecoder();
decoder.MemoryPool = context.MemoryPool;
decoder.SetInput(input);
decoder.Identify();
// Validate we are capable of decoding this.
TiffSize outputBufferSize = context.ImageSize;
if (decoder.Width < outputBufferSize.Width || decoder.Height < outputBufferSize.Height)
{
throw new InvalidDataException("Image dimension is too small.");
}
// Check number of components
if (decoder.NumberOfComponents != _numberOfComponents)
{
throw new InvalidDataException($"Expect {_numberOfComponents} components, but got {decoder.NumberOfComponents} components in the JPEG stream.");
}
JpegBlockOutputWriter outputWriter;
if (decoder.Precision == 8)
{
if (context.BitsPerSample.GetFirstOrDefault() != 8)
{
throw new InvalidDataException("Precision of 8 bit is not expected.");
}
outputWriter = new JpegBuffer8BitOutputWriter(outputBufferSize.Width, context.SkippedScanlines, context.SkippedScanlines + context.RequestedScanlines, decoder.NumberOfComponents, output);
}
else if (decoder.Precision < 8)
{
if (context.BitsPerSample.GetFirstOrDefault() != 8)
{
throw new InvalidDataException($"Precision of {decoder.Precision} bit is not expected.");
}
outputWriter = new JpegBufferAny8BitOutputWriter(outputBufferSize.Width, context.SkippedScanlines, context.SkippedScanlines + context.RequestedScanlines, decoder.NumberOfComponents, decoder.Precision, output);
}
else if (decoder.Precision <= 16)
{
if (context.BitsPerSample.GetFirstOrDefault() != 16)
{
throw new InvalidDataException($"Precision of {decoder.Precision} bit is not expected.");
}
outputWriter = new JpegBufferAny16BitOutputWriter(outputBufferSize.Width, context.SkippedScanlines, context.SkippedScanlines + context.RequestedScanlines, decoder.NumberOfComponents, decoder.Precision, output);
}
else
{
throw new InvalidDataException($"Precision of {decoder.Precision} bit is not expected.");
}
// Decode
decoder.SetOutputWriter(outputWriter);
decoder.Decode();
// Reset state
decoder.ResetInput();
decoder.ResetHeader();
decoder.ResetOutputWriter();
// Cache the instances
Interlocked.CompareExchange(ref _decoder, decoder, null);
}