root/trunk/include/mapnik/jpeg_io.hpp

/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 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
 *
 *****************************************************************************/

//$Id$
#if defined(HAVE_JPEG)

#include <mapnik/global.hpp>

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

namespace mapnik {

#define BUFFER_SIZE 4096
   
typedef struct  
{
    struct jpeg_destination_mgr pub;
    std::ostream * out;
    JOCTET * buffer;
} dest_mgr;
   
inline void init_destination( j_compress_ptr cinfo)
{
    dest_mgr * dest = reinterpret_cast<dest_mgr*>(cinfo->dest);
    dest->buffer = (JOCTET*) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                                         BUFFER_SIZE * sizeof(JOCTET));
    dest->pub.next_output_byte = dest->buffer;
    dest->pub.free_in_buffer = BUFFER_SIZE;
}

inline boolean empty_output_buffer (j_compress_ptr cinfo)
{
    dest_mgr * dest = reinterpret_cast<dest_mgr*>(cinfo->dest);
    dest->out->write((char*)dest->buffer, BUFFER_SIZE);
    if (!*(dest->out)) return false;
    dest->pub.next_output_byte = dest->buffer;
    dest->pub.free_in_buffer = BUFFER_SIZE;
    return true;
}
   
inline void term_destination( j_compress_ptr cinfo)
{
    dest_mgr * dest = reinterpret_cast<dest_mgr*>(cinfo->dest);
    size_t size  = BUFFER_SIZE - dest->pub.free_in_buffer;
    if (size > 0) 
    {
        dest->out->write((char*)dest->buffer, size);
    }
    dest->out->flush();
}
   
template <typename T1, typename T2>
void save_as_jpeg(T1 & file,int quality, T2 const& image)
{  
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr jerr;

    int width=image.width();
    int height=image.height();
        
    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);
    
    cinfo.dest = (struct jpeg_destination_mgr *)(*cinfo.mem->alloc_small)
        ((j_common_ptr) &cinfo, JPOOL_PERMANENT, sizeof(dest_mgr));
    dest_mgr * dest = (dest_mgr*) cinfo.dest;
    dest->pub.init_destination = init_destination;
    dest->pub.empty_output_buffer = empty_output_buffer;
    dest->pub.term_destination = term_destination;
    dest->out = &file;
      
    //jpeg_stdio_dest(&cinfo, fp);
    cinfo.image_width = width;
    cinfo.image_height = height;
    cinfo.input_components = 3;
    cinfo.in_color_space = JCS_RGB; 
    jpeg_set_defaults(&cinfo);
    jpeg_set_quality(&cinfo, quality,1);
    jpeg_start_compress(&cinfo, 1);
    JSAMPROW row_pointer[1];
    JSAMPLE* row=reinterpret_cast<JSAMPLE*>( ::operator new (sizeof(JSAMPLE) * width*3));
    while (cinfo.next_scanline < cinfo.image_height) 
    {
        const unsigned* imageRow=image.getRow(cinfo.next_scanline);
        int index=0;
        for (int i=0;i<width;++i)
        {
#ifdef MAPNIK_BIG_ENDIAN
            row[index++]=(imageRow[i]>>24)&0xff;
            row[index++]=(imageRow[i]>>16)&0xff;
            row[index++]=(imageRow[i]>>8)&0xff;
#else
            row[index++]=(imageRow[i])&0xff;
            row[index++]=(imageRow[i]>>8)&0xff;
            row[index++]=(imageRow[i]>>16)&0xff;
#endif
        }
        row_pointer[0] = &row[0];
        (void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
    }
    ::operator delete(row);
      
    jpeg_finish_compress(&cinfo);
    jpeg_destroy_compress(&cinfo);
}  
}

#endif