Issue #118: First part of splitting

Pdf4QtLibCore/sources/pdfccittfaxdecoder.h

@@ -0,0 +1,133 @@
+//    Copyright (C) 2019-2021 Jakub Melka
+//
+//    This file is part of PDF4QT.
+//
+//    PDF4QT is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Lesser General Public License as published by
+//    the Free Software Foundation, either version 3 of the License, or
+//    with the written consent of the copyright owner, any later version.
+//
+//    PDF4QT is distributed in the hope that it will be useful,
+//    but WITHOUT ANY WARRANTY; without even the implied warranty of
+//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//    GNU Lesser General Public License for more details.
+//
+//    You should have received a copy of the GNU Lesser General Public License
+//    along with PDF4QT.  If not, see <https://www.gnu.org/licenses/>.
+
+#ifndef PDFCCITTFAXDECODER_H
+#define PDFCCITTFAXDECODER_H
+
+#include "pdfutils.h"
+#include "pdfimage.h"
+
+namespace pdf
+{
+
+struct PDFCCITTCode;
+
+struct PDFCCITTFaxDecoderParameters
+{
+    /// Type of encoding. Has this meaning:
+    ///    K < 0 - pure two dimensional encoding (Group 4)
+    ///    K = 0 - pure one dimensional encoding
+    ///    K > 0 - mixed encoding; one dimensional encoded line can be followed by at most K - 1 two dimensional encoded lines
+    PDFInteger K = 0;
+
+    /// Pixel width of the image. Default value is 1728.
+    PDFInteger columns = 1728;
+
+    /// Pixel height of the image. This value can be zero or be absent, in this case,
+    /// end of block pattern must be present and end the stream.
+    PDFInteger rows = 0;
+
+    /// This parameter is ignored in this library. If positive, and \p hasEndOfLine is true,
+    /// and K is nonnegative, then if error occurs, end-of-line pattern is searched and
+    /// data are copied from previous line, or are set to white, if previous line is also damaged.
+    PDFInteger damagedRowsBeforeError = 0;
+
+    /// Flag indicating, that end of line patterns are required in the encoded data.
+    /// Stream filter must always accept end of line patterns, but require them only,
+    /// if this flag is set to true.
+    bool hasEndOfLine = false;
+
+    /// Flag indicating that lines are byte aligned, i.e. 0 bits are inserted before each line
+    /// to achieve byte alignment.
+    bool hasEncodedByteAlign = false;
+
+    /// Flag indicating, that filter expects the data be terminated by end of block bit pattern.
+    /// In this case, \p rows parameter is ignored. Otherwise, rows parameter is used, or image
+    /// is terminated by end of data stream, whichever occurs first. The end of block is marked
+    /// as end-of-facsimile block (EOFB), or return to control (RTC), according the K parameter.
+    bool hasEndOfBlock = true;
+
+    /// If this flag is true, then 1 means black pixel, 0 white pixel. Otherwise, if false,
+    /// then 0 means black pixel and 1 white pixel.
+    bool hasBlackIsOne = false;
+
+    /// Decode
+    std::vector<PDFReal> decode;
+
+    /// Masking type
+    PDFImageData::MaskingType maskingType = PDFImageData::MaskingType::None;
+};
+
+enum CCITT_2D_Code_Mode
+{
+    Pass,
+    Horizontal,
+    Vertical_3L,
+    Vertical_2L,
+    Vertical_1L,
+    Vertical_0,
+    Vertical_1R,
+    Vertical_2R,
+    Vertical_3R,
+    Invalid
+};
+
+class PDFCCITTFaxDecoder
+{
+public:
+    explicit PDFCCITTFaxDecoder(const QByteArray* stream, const PDFCCITTFaxDecoderParameters& parameters);
+
+    PDFImageData decode();
+
+    const PDFBitReader* getReader() const { return &m_reader; }
+
+private:
+    /// Skip zero bits at the start
+    void skipFill();
+
+    /// Skip end-of-line, if occured. Returns true, if EOL was skipped.
+    bool skipEOL();
+
+    /// Skip fill bits and then try to skip EOL. If EOL is found, then
+    /// true is returned, otherwise false is returned.
+    bool skipFillAndEOL() { skipFill(); return skipEOL(); }
+
+    /// Add pixels to the line.
+    /// \param line Line with changing element indices
+    /// \param a0_index Reference changing element index (index to the \p line array)
+    /// \param a1 Current changing element index (column index, not index to the \p line array)
+    /// \param isCurrentPixelBlack Are pixels black?
+    /// \param isA1LeftOfA0Allowed Allow a1 to be left of a0 (not a0_index, but line[a0_index], which is a0)
+    void addPixels(std::vector<int>& line, int& a0_index, int a1, bool isCurrentPixelBlack, bool isA1LeftOfA0Allowed);
+
+    /// Get 2D mode from the stream
+    CCITT_2D_Code_Mode get2DMode();
+
+    uint32_t getRunLength(bool white);
+
+    uint32_t getWhiteCode();
+    uint32_t getBlackCode();
+
+    uint32_t getCode(const PDFCCITTCode* codes, size_t codeCount);
+
+    PDFBitReader m_reader;
+    PDFCCITTFaxDecoderParameters m_parameters;
+};
+
+}   // namespace pdf
+
+#endif // PDFCCITTFAXDECODER_H