File: JpegWriter.cc

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//========================================================================
//
// JpegWriter.cc
//
// This file is licensed under the GPLv2 or later
//
// Copyright (C) 2009 Stefan Thomas <thomas@eload24.com>
// Copyright (C) 2010, 2012, 2017 Adrian Johnson <ajohnson@redneon.com>
// Copyright (C) 2010 Harry Roberts <harry.roberts@midnight-labs.org>
// Copyright (C) 2011 Thomas Freitag <Thomas.Freitag@alfa.de>
// Copyright (C) 2013 Peter Breitenlohner <peb@mppmu.mpg.de>
// Copyright (C) 2017, 2018 Albert Astals Cid <aacid@kde.org>
// Copyright (C) 2018 Martin Packman <gzlist@googlemail.com>
// Copyright (C) 2018 Ed Porras <ed@motologic.com>
//
//========================================================================

#include "JpegWriter.h"

#ifdef ENABLE_LIBJPEG

extern "C" {
#    include <jpeglib.h>
}

#    include "poppler/Error.h"

struct JpegWriterPrivate
{
    bool progressive;
    bool optimize;
    int quality;
    JpegWriter::Format format;
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;
};

static void outputMessage(j_common_ptr cinfo)
{
    char buffer[JMSG_LENGTH_MAX];

    // Create the message
    (*cinfo->err->format_message)(cinfo, buffer);

    // Send it to poppler's error handler
    error(errInternal, -1, "{0:s}", buffer);
}

JpegWriter::JpegWriter(int q, bool p, Format formatA)
{
    priv = new JpegWriterPrivate;
    priv->progressive = p;
    priv->optimize = false;
    priv->quality = q;
    priv->format = formatA;
}

JpegWriter::JpegWriter(Format formatA) : JpegWriter(-1, false, formatA) { }

JpegWriter::~JpegWriter()
{
    // cleanup
    jpeg_destroy_compress(&priv->cinfo);
    delete priv;
}

void JpegWriter::setQuality(int quality)
{
    priv->quality = quality;
}

void JpegWriter::setProgressive(bool progressive)
{
    priv->progressive = progressive;
}

void JpegWriter::setOptimize(bool optimize)
{
    priv->optimize = optimize;
}

bool JpegWriter::init(FILE *f, int width, int height, int hDPI, int vDPI)
{
    // Setup error handler
    priv->cinfo.err = jpeg_std_error(&priv->jerr);
    priv->jerr.output_message = &outputMessage;

    // Initialize libjpeg
    jpeg_create_compress(&priv->cinfo);

    // First set colorspace and call jpeg_set_defaults() since
    // jpeg_set_defaults() sets default values for all fields in
    // cinfo based on the colorspace.
    switch (priv->format) {
    case RGB:
        priv->cinfo.in_color_space = JCS_RGB;
        break;
    case GRAY:
        priv->cinfo.in_color_space = JCS_GRAYSCALE;
        break;
    case CMYK:
        priv->cinfo.in_color_space = JCS_CMYK;
        break;
    default:
        return false;
    }
    jpeg_set_defaults(&priv->cinfo);

    // Set destination file
    jpeg_stdio_dest(&priv->cinfo, f);

    // Set libjpeg configuration
    priv->cinfo.image_width = width;
    priv->cinfo.image_height = height;
    priv->cinfo.density_unit = 1; // dots per inch
    priv->cinfo.X_density = hDPI;
    priv->cinfo.Y_density = vDPI;
    switch (priv->format) {
    case GRAY:
        priv->cinfo.input_components = 1;
        break;
    case RGB:
        priv->cinfo.input_components = 3;
        break;
    case CMYK:
        priv->cinfo.input_components = 4;
        jpeg_set_colorspace(&priv->cinfo, JCS_YCCK);
        priv->cinfo.write_JFIF_header = TRUE;
        break;
    default:
        return false;
    }

    // Set quality
    if (priv->quality >= 0 && priv->quality <= 100) {
        jpeg_set_quality(&priv->cinfo, priv->quality, TRUE);
    }

    // Use progressive mode
    if (priv->progressive) {
        jpeg_simple_progression(&priv->cinfo);
    }

    // Set whether to compute optimal Huffman coding tables
    priv->cinfo.optimize_coding = static_cast<boolean>(priv->optimize);

    // Get ready for data
    jpeg_start_compress(&priv->cinfo, TRUE);

    return true;
}

bool JpegWriter::writePointers(unsigned char **rowPointers, int rowCount)
{
    if (priv->format == CMYK) {
        for (int y = 0; y < rowCount; y++) {
            unsigned char *row = rowPointers[y];
            for (unsigned int x = 0; x < priv->cinfo.image_width; x++) {
                for (int n = 0; n < 4; n++) {
                    *row = 0xff - *row;
                    row++;
                }
            }
        }
    }
    // Write all rows to the file
    jpeg_write_scanlines(&priv->cinfo, rowPointers, rowCount);

    return true;
}

bool JpegWriter::writeRow(unsigned char **rowPointer)
{
    if (priv->format == CMYK) {
        unsigned char *row = rowPointer[0];
        for (unsigned int x = 0; x < priv->cinfo.image_width; x++) {
            for (int n = 0; n < 4; n++) {
                *row = 0xff - *row;
                row++;
            }
        }
    }
    // Write the row to the file
    jpeg_write_scanlines(&priv->cinfo, rowPointer, 1);

    return true;
}

bool JpegWriter::close()
{
    jpeg_finish_compress(&priv->cinfo);

    return true;
}

bool JpegWriter::supportCMYK()
{
    return priv->format == CMYK;
}

#endif