png_io_private.hpp

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        png_uint_32 width, height;
        int bit_depth, color_type, interlace_type;
        png_get_IHDR(_png_ptr, _info_ptr,
                     &width, &height,&bit_depth,&color_type,&interlace_type,
                     int_p_NULL, int_p_NULL);
        io_error_if(((png_uint_32)view.width()!=width || (png_uint_32)view.height()!= height),
                    "png_read_view: input view size does not match PNG file size");
        
        if(png_read_support_private<typename channel_type<View>::type,
                                    typename color_space_type<View>::type>::bit_depth!=bit_depth ||
           png_read_support_private<typename channel_type<View>::type,
                                    typename color_space_type<View>::type>::color_type!=color_type)
            io_error("png_read_view: input view type is incompatible with the image type");
        
        std::vector<pixel<typename channel_type<View>::type,
                          layout<typename color_space_type<View>::type> > > row(width);
        for(png_uint_32 y=0;y<height;++y) {
            png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
            std::copy(row.begin(),row.end(),view.row_begin(y));
        }
        png_read_end(_png_ptr,NULL);
    }

    template <typename Image>
    void read_image(Image& im) {
        im.recreate(get_dimensions());
        apply(view(im));
    }
};

// This code will be simplified...
template <typename CC>
class png_reader_color_convert : public png_reader {
private:
    CC _cc;
public:
    png_reader_color_convert(FILE* file          ,CC cc_in) : png_reader(file),_cc(cc_in) {}
    png_reader_color_convert(FILE* file          ) : png_reader(file) {}
    png_reader_color_convert(const char* filename,CC cc_in) : png_reader(filename),_cc(cc_in) {}
    png_reader_color_convert(const char* filename) : png_reader(filename) {}
    template <typename View>
    void apply(const View& view) {
        png_uint_32 width, height;
        int bit_depth, color_type, interlace_type;
        png_get_IHDR(_png_ptr, _info_ptr,
                     &width, &height,&bit_depth,&color_type,&interlace_type,
                     int_p_NULL, int_p_NULL);
        io_error_if(((png_uint_32)view.width()!=width || (png_uint_32)view.height()!= height),
                    "png_reader_color_convert::apply(): input view size does not match PNG file size");
        switch (color_type) {
        case PNG_COLOR_TYPE_GRAY:
            switch (bit_depth) {
            case 8: {
                std::vector<gray8_pixel_t> row(width);
                for(png_uint_32 y=0;y<height;++y) {
                    png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
                    std::transform(row.begin(),row.end(),view.row_begin(y),color_convert_deref_fn<gray8_ref_t,typename View::value_type,CC>(_cc));
                }
                break;
            }
            case 16: {
                std::vector<gray16_pixel_t> row(width);
                for(png_uint_32 y=0;y<height;++y) {
                    png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
                    std::transform(row.begin(),row.end(),view.row_begin(y),color_convert_deref_fn<gray16_ref_t,typename View::value_type,CC>(_cc));
                }
                break;
            }
            default: io_error("png_reader_color_convert::apply(): unknown combination of color type and bit depth");
            }
            break;
        case PNG_COLOR_TYPE_RGB:
            switch (bit_depth) {
            case 8: {
                std::vector<rgb8_pixel_t> row(width);
                for(png_uint_32 y=0;y<height;++y) {
                    png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
                    std::transform(row.begin(),row.end(),view.row_begin(y),color_convert_deref_fn<rgb8_ref_t,typename View::value_type,CC>(_cc));
                }
                break;
            }
            case 16: {
                std::vector<rgb16_pixel_t> row(width);
                for(png_uint_32 y=0;y<height;++y) {
                    png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
                    std::transform(row.begin(),row.end(),view.row_begin(y),color_convert_deref_fn<rgb16_ref_t,typename View::value_type,CC>(_cc));
                }
                break;
            }
            default: io_error("png_reader_color_convert::apply(): unknown combination of color type and bit depth");
            }
            break;
        case PNG_COLOR_TYPE_RGBA:
            switch (bit_depth) {
            case 8: {
                std::vector<rgba8_pixel_t> row(width);
                for(png_uint_32 y=0;y<height;++y) {
                    png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
                    std::transform(row.begin(),row.end(),view.row_begin(y),color_convert_deref_fn<rgba8_ref_t,typename View::value_type,CC>(_cc));
                }
                break;
            }
            case 16: {
                std::vector<rgba16_pixel_t> row(width);
                for(png_uint_32 y=0;y<height;++y) {
                    png_read_row(_png_ptr,(png_bytep)&row.front(),NULL);
                    std::transform(row.begin(),row.end(),view.row_begin(y),color_convert_deref_fn<rgba16_ref_t,typename View::value_type,CC>(_cc));
                }
                break;
            }
            default: io_error("png_reader_color_convert::apply(): unknown combination of color type and bit depth");
            }
            break;
        default: io_error("png_reader_color_convert::apply(): unknown color type");
        }
        png_read_end(_png_ptr,NULL);
    }
    template <typename Image>
    void read_image(Image& im) {
        im.recreate(get_dimensions());
        apply(view(im));
    }
};


class png_writer : public file_mgr {
protected:
    png_structp _png_ptr;
    png_infop _info_ptr;

    void init() {
        _png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
        io_error_if(!_png_ptr,"png_write_initialize: fail to call png_create_write_struct()");
        _info_ptr = png_create_info_struct(_png_ptr);
        if (!_info_ptr) {
            png_destroy_write_struct(&_png_ptr,png_infopp_NULL);
            io_error("png_write_initialize: fail to call png_create_info_struct()");
        }
        if (setjmp(png_jmpbuf(_png_ptr))) {
            png_destroy_write_struct(&_png_ptr, &_info_ptr);
            io_error("png_write_initialize: fail to call setjmp(png_jmpbuf())");
        }
        png_init_io(_png_ptr,get());
    }
public:
    png_writer(FILE* file          ) : file_mgr(file)           { init(); }
    png_writer(const char* filename) : file_mgr(filename, "wb") { init(); }

    ~png_writer() {
        png_destroy_write_struct(&_png_ptr,&_info_ptr);
    }
    template <typename View>
    void apply(const View& view) {
        png_set_IHDR(_png_ptr, _info_ptr, view.width(), view.height(),
                     png_write_support_private<typename channel_type<View>::type,
                                               typename color_space_type<View>::type>::bit_depth,
                     png_write_support_private<typename channel_type<View>::type,
                                               typename color_space_type<View>::type>::color_type,
                     PNG_INTERLACE_NONE,
                     PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
        png_write_info(_png_ptr,_info_ptr);
        if (little_endian() &&
            png_write_support_private<typename channel_type<View>::type,
                                      typename color_space_type<View>::type>::bit_depth>8)
            png_set_swap(_png_ptr);
        std::vector<pixel<typename channel_type<View>::type,
                          layout<typename color_space_type<View>::type> > > row(view.width());
        for(int y=0;y<view.height();++y) {
            std::copy(view.row_begin(y),view.row_end(y),row.begin());
            png_write_row(_png_ptr,(png_bytep)&row.front());
        }
        png_write_end(_png_ptr,_info_ptr);
    }
};

} // namespace detail
} }  // namespace boost::gil

#endif