public JpegArithmeticSequentialScanDecoder(JpegDecoder decoder, JpegFrameHeader frameHeader) : base(decoder)
{
_frameHeader = frameHeader;
// Compute maximum sampling factor
int maxHorizontalSampling = 1;
int maxVerticalSampling = 1;
foreach (JpegFrameComponentSpecificationParameters currentFrameComponent in frameHeader.Components !)
{
maxHorizontalSampling = Math.Max(maxHorizontalSampling, currentFrameComponent.HorizontalSamplingFactor);
maxVerticalSampling = Math.Max(maxVerticalSampling, currentFrameComponent.VerticalSamplingFactor);
}
_maxHorizontalSampling = maxHorizontalSampling;
_maxVerticalSampling = maxVerticalSampling;
_restartInterval = decoder.GetRestartInterval();
_mcusPerLine = (frameHeader.SamplesPerLine + 8 * maxHorizontalSampling - 1) / (8 * maxHorizontalSampling);
_mcusPerColumn = (frameHeader.NumberOfLines + 8 * maxVerticalSampling - 1) / (8 * maxVerticalSampling);
_levelShift = 1 << (frameHeader.SamplePrecision - 1);
// Pre-allocate the JpegDecodeComponent instances
_components = new JpegArithmeticDecodingComponent[frameHeader.NumberOfComponents];
for (int i = 0; i < _components.Length; i++)
{
_components[i] = new JpegArithmeticDecodingComponent();
}
}
public JpegHuffmanLosslessScanDecoder(JpegDecoder decoder, JpegFrameHeader frameHeader) : base(decoder)
{
_frameHeader = frameHeader;
// Compute maximum sampling factor
int maxHorizontalSampling = 1;
int maxVerticalSampling = 1;
foreach (JpegFrameComponentSpecificationParameters currentFrameComponent in frameHeader.Components !)
{
maxHorizontalSampling = Math.Max(maxHorizontalSampling, currentFrameComponent.HorizontalSamplingFactor);
maxVerticalSampling = Math.Max(maxVerticalSampling, currentFrameComponent.VerticalSamplingFactor);
}
_restartInterval = decoder.GetRestartInterval();
_mcusPerLine = (frameHeader.SamplesPerLine + maxHorizontalSampling - 1) / maxHorizontalSampling;
_mcusPerColumn = (frameHeader.NumberOfLines + maxVerticalSampling - 1) / maxVerticalSampling;
JpegBlockOutputWriter?outputWriter = decoder.GetOutputWriter();
if (outputWriter is null)
{
ThrowInvalidDataException("Output writer is not set.");
}
_allocator = new JpegPartialScanlineAllocator(outputWriter, decoder.MemoryPool);
_allocator.Allocate(frameHeader);
// Pre-allocate the JpegDecodeComponent instances
_components = new JpegHuffmanDecodingComponent[frameHeader.NumberOfComponents];
for (int i = 0; i < _components.Length; i++)
{
_components[i] = new JpegHuffmanDecodingComponent();
}
}