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CCITT fax decoder, finishing

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Jakub Melka
2019-10-13 19:02:38 +02:00
parent e20dfe6a5c
commit b1b5780753
4 changed files with 116 additions and 9 deletions
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63
PdfForQtLib/sources/pdfccittfaxdecoder.cpp
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@ -312,7 +312,7 @@ PDFImageData PDFCCITTFaxDecoder::decode()
int row = 0;
const size_t lineSize = m_parameters.columns + 2;
codingLine.resize(lineSize, m_parameters.columns);
codingLine.resize(lineSize, 0);
referenceLine.resize(lineSize, m_parameters.columns);
bool isUsing2DEncoding = m_parameters.K < 0;
bool isEndOfLineOccured = m_parameters.hasEndOfLine;
@ -334,7 +334,6 @@ PDFImageData PDFCCITTFaxDecoder::decode()
int a0_index = 0;
bool isCurrentPixelBlack = false;
if (isUsing2DEncoding)
{
int b1_index = 0;
@ -444,22 +443,74 @@ PDFImageData PDFCCITTFaxDecoder::decode()
++index;
}
writer.write((isCurrentPixelBlack != m_parameters.hasBlackIsOne) ? 0 : 1);
writer.write((isCurrentPixelBlack != m_parameters.hasBlackIsOne) ? 1 : 0);
}
writer.finishLine();
++row;
// Check if we have reached desired number of rows (and end-of-block mode
// is not set). If yes, then break the reading.
if (!m_parameters.hasEndOfBlock && row == m_parameters.rows)
{
// We have reached number of rows, stop reading the data
break;
}
pokracovat zde
bool foundEndOfLine = false;
if (m_parameters.hasEndOfLine)
{
// End of line is required, try to scan it (until end of stream is reached).
while (!m_reader.isAtEnd())
{
if (m_reader.look(12) == 1)
{
m_reader.read(12);
foundEndOfLine = true;
break;
}
else
{
m_reader.read(1);
}
}
}
else if (!m_parameters.hasEncodedByteAlign)
{
// Skip fill zeros and possibly find EOL
foundEndOfLine = skipFillAndEOL();
}
// If end of line is found, be do not perform align to bytes (end of line
// has perference against byte align)
if (m_parameters.hasEncodedByteAlign && !foundEndOfLine)
{
m_reader.alignToBytes();
}
if (m_reader.isAtEnd())
{
// Have we finished reading?
break;
}
updateIsUsing2DEncoding();
if (m_parameters.hasEndOfBlock && foundEndOfLine)
{
if (m_reader.look(60) == 0x1001001001001ULL)
{
// End of block found, stop reading the data
break;
}
}
std::swap(codingLine, referenceLine);
std::fill(codingLine.begin(), codingLine.end(), 0);
std::fill(std::next(referenceLine.begin(), a0_index + 1), referenceLine.end(), m_parameters.columns);
}
return PDFImageData(1, 1, m_parameters.columns, row, (m_parameters.columns + 7) / 8, m_parameters.maskingType, writer.takeByteArray(), { }, { }, { });
}
void PDFCCITTFaxDecoder::skipFill()
@ -467,7 +518,7 @@ void PDFCCITTFaxDecoder::skipFill()
// This functions skips zero bits (because codewords have at most 12 bits,
// we use 12 bit lookahead to ensure, that we do not broke data sequence).
while (m_reader.look(12) == 0)
while (!m_reader.isAtEnd() && m_reader.look(12) == 0)
{
m_reader.read(1);
}