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/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2011 Artem Pavlenko
*
* This library 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 2.1 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*****************************************************************************/
// mapnik
#include <mapnik/image_reader.hpp>
#include <mapnik/color.hpp>
// jpeg
extern "C"
{
#include <jpeglib.h>
}
// boost
#include <boost/scoped_array.hpp>
#include <boost/utility.hpp>
// std
#include <cstdio>
namespace mapnik
{
class JpegReader : public image_reader, boost::noncopyable
{
private:
std::string fileName_;
unsigned width_;
unsigned height_;
public:
explicit JpegReader(std::string const& fileName);
~JpegReader();
unsigned width() const;
unsigned height() const;
inline bool premultiplied_alpha() const { return true; }
void read(unsigned x,unsigned y,image_data_32& image);
private:
void init();
};
namespace
{
image_reader* createJpegReader(std::string const& file)
{
return new JpegReader(file);
}
const bool registered = register_image_reader("jpeg",createJpegReader);
}
JpegReader::JpegReader(std::string const& fileName)
: fileName_(fileName),
width_(0),
height_(0)
{
init();
}
JpegReader::~JpegReader() {}
void JpegReader::init()
{
FILE *fp = fopen(fileName_.c_str(),"rb");
if (!fp) throw image_reader_exception("JPEG Reader: cannot open image file " + fileName_);
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, fp);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
width_ = cinfo.output_width;
height_ = cinfo.output_height;
// if enabled: "Application transferred too few scanlines"
//jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(fp);
}
unsigned JpegReader::width() const
{
return width_;
}
unsigned JpegReader::height() const
{
return height_;
}
void JpegReader::read(unsigned x0, unsigned y0, image_data_32& image)
{
struct jpeg_decompress_struct cinfo;
FILE *fp = fopen(fileName_.c_str(),"rb");
if (!fp) throw image_reader_exception("JPEG Reader: cannot open image file " + fileName_);
struct jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, fp);
jpeg_read_header(&cinfo, TRUE);
if (cinfo.out_color_space == JCS_UNKNOWN)
throw image_reader_exception("JPEG Reader: failed to read unknown color space in " + fileName_);
jpeg_start_decompress(&cinfo);
if (cinfo.output_width == 0) {
jpeg_destroy_decompress (&cinfo);
fclose(fp);
throw image_reader_exception("JPEG Reader: failed to read image size of " + fileName_);
}
JSAMPARRAY buffer;
int row_stride;
unsigned char a,r,g,b;
row_stride = cinfo.output_width * cinfo.output_components;
buffer = (*cinfo.mem->alloc_sarray) ((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
unsigned w = std::min(unsigned(image.width()),width_);
unsigned h = std::min(unsigned(image.height()),height_);
boost::scoped_array<unsigned int> out_row(new unsigned int[w]);
// TODO - handle x0
for (unsigned i=0;i<h;++i)
{
jpeg_read_scanlines(&cinfo, buffer, 1);
if (i>=y0 && i<h)
{
for (unsigned int x=0; x<w; x++)
{
a = 255; // alpha not supported in jpg
r = buffer[0][cinfo.output_components * x];
if (cinfo.output_components > 2)
{
g = buffer[0][cinfo.output_components*x+1];
b = buffer[0][cinfo.output_components*x+2];
} else {
g = r;
b = r;
}
out_row[x] = color(r, g, b, a).rgba();
}
image.setRow(i-y0, out_row.get(), w);
}
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(fp);
}
}
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