mapnik/src/image_util.cpp

/*****************************************************************************
 * 
 * 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: image_util.cpp 36 2005-04-05 14:32:18Z pavlenko $

// stl
#include <string>
// mapnik
#include <mapnik/graphics.hpp>
#include <mapnik/memory.hpp>
#include <mapnik/image_util.hpp>
#include <mapnik/image_view.hpp>
// jpeg png
extern "C"
{
#include <png.h>
#include <jpeglib.h>
}

namespace mapnik
{ 
    template <typename T>
    void save_to_file(std::string const& filename,
                      std::string const& type,
                      T const& image)
    {
        //all that should go into image_writer factory
        if (type=="png")
        {
            save_as_png(filename,image);
        } 
        else if (type=="jpeg")
        {
            save_as_jpeg(filename,85,image);
        }
    }
    
    template <typename T>
    void save_as_png(std::string const& filename, T const& image)
    {
        FILE *fp=fopen(filename.c_str(), "wb");
        if (!fp) return;
        png_voidp error_ptr=0;
        png_structp png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING,
                                                    error_ptr,0, 0);

        if (!png_ptr) return;

        // switch on optimization only if supported
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200) && defined(PNG_ASSEMBLER_CODE_SUPPORTED)
        png_uint_32 mask, flags;

        flags = png_get_asm_flags(png_ptr);
        mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
        png_set_asm_flags(png_ptr, flags | mask);
#endif
        png_set_filter (png_ptr, 0, PNG_FILTER_NONE);
        png_infop info_ptr = png_create_info_struct(png_ptr);
        if (!info_ptr)
        {
            png_destroy_write_struct(&png_ptr,(png_infopp)0);
            fclose(fp);
            return;
        }
        if (setjmp(png_jmpbuf(png_ptr)))
        {
            png_destroy_write_struct(&png_ptr, &info_ptr);
            fclose(fp);
            return;
        }

        png_init_io(png_ptr, fp);
        //png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
        //png_set_compression_strategy(png_ptr, Z_FILTERED);
        png_set_IHDR(png_ptr, info_ptr,image.width(),image.height(),8,
                     PNG_COLOR_TYPE_RGB_ALPHA,PNG_INTERLACE_NONE,
                     PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
        png_write_info(png_ptr, info_ptr);
        for (unsigned i=0;i<image.height();i++)
        {
            png_write_row(png_ptr,(png_bytep)image.getRow(i));
        }

        png_write_end(png_ptr, info_ptr);
        png_destroy_write_struct(&png_ptr, &info_ptr);
        fclose(fp);
    }
    
    template <typename T>
    void save_as_jpeg(std::string const& filename,int quality, T const& image)
    {
        FILE *fp=fopen(filename.c_str(), "wb");
        if (!fp) return;
        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);
        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=new 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)
            {
                row[index++]=(imageRow[i])&0xff;
                row[index++]=(imageRow[i]>>8)&0xff;
                row[index++]=(imageRow[i]>>16)&0xff;
            }
            row_pointer[0] = &row[0];
            (void) jpeg_write_scanlines(&cinfo, row_pointer, 1);
        }
        delete [] row;
        jpeg_finish_compress(&cinfo);
        fclose(fp);
        jpeg_destroy_compress(&cinfo);
    }  
    
    template void save_to_file<ImageData32>(std::string const&,
                                            std::string const& , 
                                            ImageData32 const&);

    template void save_to_file<image_view<ImageData32> > (std::string const&,
                                                          std::string const& , 
                                                          image_view<ImageData32> const&);
    
}