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TIFF predictor

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This commit is contained in:
Jakub Melka
2019-10-05 17:38:15 +02:00
parent f8d72d1960
commit f443aec09c
4 changed files with 100 additions and 5 deletions
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44
PdfForQtLib/sources/pdfutils.cpp
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@ -84,4 +84,48 @@ bool PDFBitReader::isAtEnd() const
return (m_position >= m_stream->size());
}
PDFBitWriter::PDFBitWriter(Value bitsPerComponent) :
m_bitsPerComponent(bitsPerComponent),
m_mask((static_cast<Value>(1) << m_bitsPerComponent) - static_cast<Value>(1)),
m_buffer(0),
m_bitsInBuffer(0)
{
}
void PDFBitWriter::write(Value value)
{
m_buffer = (m_buffer << m_bitsPerComponent) | (value & m_mask);
m_bitsInBuffer += m_bitsPerComponent;
flush(false);
}
void PDFBitWriter::flush(bool alignToByteBoundary)
{
if (m_bitsInBuffer >= 8)
{
Value remainder = m_bitsInBuffer % 8;
Value alignedBuffer = m_buffer >> remainder;
Value bitsToWrite = m_bitsInBuffer - remainder;
Value bytesToWrite = bitsToWrite / 8;
for (Value byteIndex = 0; byteIndex < bytesToWrite; ++byteIndex)
{
const Value shift = (bytesToWrite - 1 - byteIndex) * 8;
m_outputByteArray.push_back(static_cast<const char>(static_cast<uint8_t>((alignedBuffer >> shift) & 0xFF)));
}
m_bitsInBuffer = remainder;
}
if (alignToByteBoundary && m_bitsInBuffer > 0)
{
Value missingBits = 8 - m_bitsInBuffer % 8;
m_buffer = m_buffer << missingBits;
m_bitsInBuffer += missingBits;
flush(false);
}
}
} // namespace pdf