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122 lines
4.5 KiB
C++
122 lines
4.5 KiB
C++
// Copyright (C) 2019-2020 Jakub Melka
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//
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// This file is part of Pdf4Qt.
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//
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// Pdf4Qt 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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// Pdf4Qt 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 Pdf4Qt. If not, see <https://www.gnu.org/licenses/>.
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#ifndef PDFCCITTFAXDECODER_H
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#define PDFCCITTFAXDECODER_H
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#include "pdfutils.h"
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#include "pdfimage.h"
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namespace pdf
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{
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struct PDFCCITTCode;
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struct PDFCCITTFaxDecoderParameters
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{
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/// Type of encoding. Has this meaning:
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/// K < 0 - pure two dimensional encoding (Group 4)
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/// K = 0 - pure one dimensional encoding
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/// K > 0 - mixed encoding; one dimensional encoded line can be followed by at most K - 1 two dimensional encoded lines
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PDFInteger K = 0;
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/// Pixel width of the image. Default value is 1728.
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PDFInteger columns = 1728;
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/// Pixel height of the image. This value can be zero or be absent, in this case,
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/// end of block pattern must be present and end the stream.
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PDFInteger rows = 0;
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/// This parameter is ignored in this library. If positive, and \p hasEndOfLine is true,
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/// and K is nonnegative, then if error occurs, end-of-line pattern is searched and
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/// data are copied from previous line, or are set to white, if previous line is also damaged.
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PDFInteger damagedRowsBeforeError = 0;
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/// Flag indicating, that end of line patterns are required in the encoded data.
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/// Stream filter must always accept end of line patterns, but require them only,
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/// if this flag is set to true.
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bool hasEndOfLine = false;
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/// Flag indicating that lines are byte aligned, i.e. 0 bits are inserted before each line
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/// to achieve byte alignment.
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bool hasEncodedByteAlign = false;
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/// Flag indicating, that filter expects the data be terminated by end of block bit pattern.
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/// In this case, \p rows parameter is ignored. Otherwise, rows parameter is used, or image
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/// is terminated by end of data stream, whichever occurs first. The end of block is marked
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/// as end-of-facsimile block (EOFB), or return to control (RTC), according the K parameter.
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bool hasEndOfBlock = true;
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/// If this flag is true, then 1 means black pixel, 0 white pixel. Otherwise, if false,
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/// then 0 means black pixel and 1 white pixel.
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bool hasBlackIsOne = false;
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/// Decode
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std::vector<PDFReal> decode;
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/// Masking type
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PDFImageData::MaskingType maskingType = PDFImageData::MaskingType::None;
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};
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enum CCITT_2D_Code_Mode;
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class PDFCCITTFaxDecoder
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{
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public:
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explicit PDFCCITTFaxDecoder(const QByteArray* stream, const PDFCCITTFaxDecoderParameters& parameters);
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PDFImageData decode();
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const PDFBitReader* getReader() const { return &m_reader; }
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private:
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/// Skip zero bits at the start
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void skipFill();
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/// Skip end-of-line, if occured. Returns true, if EOL was skipped.
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bool skipEOL();
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/// Skip fill bits and then try to skip EOL. If EOL is found, then
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/// true is returned, otherwise false is returned.
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bool skipFillAndEOL() { skipFill(); return skipEOL(); }
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/// Add pixels to the line.
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/// \param line Line with changing element indices
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/// \param a0_index Reference changing element index (index to the \p line array)
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/// \param a1 Current changing element index (column index, not index to the \p line array)
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/// \param isCurrentPixelBlack Are pixels black?
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/// \param isA1LeftOfA0Allowed Allow a1 to be left of a0 (not a0_index, but line[a0_index], which is a0)
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void addPixels(std::vector<int>& line, int& a0_index, int a1, bool isCurrentPixelBlack, bool isA1LeftOfA0Allowed);
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/// Get 2D mode from the stream
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CCITT_2D_Code_Mode get2DMode();
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uint32_t getRunLength(bool white);
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uint32_t getWhiteCode();
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uint32_t getBlackCode();
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uint32_t getCode(const PDFCCITTCode* codes, size_t codeCount);
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PDFBitReader m_reader;
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PDFCCITTFaxDecoderParameters m_parameters;
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};
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} // namespace pdf
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#endif // PDFCCITTFAXDECODER_H
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