mirror of https://github.com/JakubMelka/PDF4QT.git
73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
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// Copyright (C) 2019 Jakub Melka
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//
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// This file is part of PdfForQt.
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//
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// PdfForQt is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// PdfForQt is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with PDFForQt. If not, see <https://www.gnu.org/licenses/>.
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#include "pdfutils.h"
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#include "pdfexception.h"
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namespace pdf
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{
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PDFBitReader::PDFBitReader(QDataStream* stream, Value bitsPerComponent) :
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m_stream(stream),
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m_bitsPerComponent(bitsPerComponent),
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m_maximalValue((static_cast<Value>(1) << m_bitsPerComponent) - static_cast<Value>(1)),
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m_buffer(0),
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m_bitsInBuffer(0)
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{
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// We need reserve, so we allow number of length of component as 1-56 bits.
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Q_ASSERT(bitsPerComponent > 0);
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Q_ASSERT(bitsPerComponent < 56);
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}
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PDFBitReader::Value PDFBitReader::read()
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{
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while (m_bitsInBuffer < m_bitsPerComponent)
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{
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if (!m_stream->atEnd())
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{
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uint8_t currentByte = 0;
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(*m_stream) >> currentByte;
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m_buffer = (m_buffer << 8) | currentByte;
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m_bitsInBuffer += 8;
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}
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else
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{
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throw PDFParserException(PDFTranslationContext::tr("Not enough data to read %1-bit value.").arg(m_bitsPerComponent));
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}
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}
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// Now we have enough bits to read the data
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Value value = (m_buffer >> (m_bitsInBuffer - m_bitsPerComponent)) & m_maximalValue;
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m_bitsInBuffer -= m_bitsPerComponent;
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return value;
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}
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void PDFBitReader::seek(qint64 position)
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{
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if (m_stream->device()->seek(position))
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{
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m_buffer = 0;
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m_bitsInBuffer = 0;
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}
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else
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{
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throw PDFParserException(PDFTranslationContext::tr("Can't seek to position %1.").arg(position));
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}
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}
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} // namespace pdf
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