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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
*
*****************************************************************************/
#include <mapnik/debug.hpp>
#include <mapnik/image_reader.hpp>
extern "C"
{
#include <png.h>
}
#include <boost/scoped_array.hpp>
#include <boost/utility.hpp>
namespace mapnik
{
class png_reader : public image_reader, boost::noncopyable
{
private:
std::string fileName_;
unsigned width_;
unsigned height_;
int bit_depth_;
int color_type_;
public:
explicit png_reader(const std::string& fileName);
~png_reader();
unsigned width() const;
unsigned height() const;
void read(unsigned x,unsigned y,image_data_32& image);
private:
void init();
};
namespace
{
image_reader* create_png_reader(const std::string& file)
{
return new png_reader(file);
}
const bool registered = register_image_reader("png",create_png_reader);
}
png_reader::png_reader(const std::string& fileName)
: fileName_(fileName),
width_(0),
height_(0),
bit_depth_(0),
color_type_(0)
{
init();
}
png_reader::~png_reader() {}
static void
png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
{
png_size_t check;
check = (png_size_t)fread(data, (png_size_t)1, length,
(FILE *)png_get_io_ptr(png_ptr));
if (check != length)
{
png_error(png_ptr, "Read Error");
}
}
void png_reader::init()
{
FILE *fp=fopen(fileName_.c_str(),"rb");
if (!fp) throw image_reader_exception("cannot open image file "+fileName_);
png_byte header[8];
memset(header,0,8);
if ( fread(header,1,8,fp) != 8)
{
fclose(fp);
throw image_reader_exception("Could not read " + fileName_);
}
int is_png=!png_sig_cmp(header,0,8);
if (!is_png)
{
fclose(fp);
throw image_reader_exception(fileName_ + " is not a png file");
}
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING,0,0,0);
if (!png_ptr)
{
fclose(fp);
throw image_reader_exception("failed to allocate png_ptr");
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,0,0);
fclose(fp);
throw image_reader_exception("failed to create info_ptr");
}
png_set_read_fn(png_ptr, (png_voidp)fp, png_read_data);
png_set_sig_bytes(png_ptr,8);
png_read_info(png_ptr, info_ptr);
png_uint_32 width, height;
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth_, &color_type_,0,0,0);
width_=width;
height_=height;
MAPNIK_LOG_DEBUG(png_reader) << "png_reader: bit_depth=" << bit_depth_ << ",color_type=" << color_type_;
png_destroy_read_struct(&png_ptr,&info_ptr,0);
fclose(fp);
}
unsigned png_reader::width() const
{
return width_;
}
unsigned png_reader::height() const
{
return height_;
}
void png_reader::read(unsigned x0, unsigned y0,image_data_32& image)
{
FILE *fp=fopen(fileName_.c_str(),"rb");
if (!fp) throw image_reader_exception("cannot open image file "+fileName_);
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING,0,0,0);
if (!png_ptr)
{
fclose(fp);
throw image_reader_exception("failed to allocate png_ptr");
}
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,0,0);
fclose(fp);
throw image_reader_exception("failed to create info_ptr");
}
png_set_read_fn(png_ptr, (png_voidp)fp, png_read_data);
png_read_info(png_ptr, info_ptr);
if (color_type_ == PNG_COLOR_TYPE_PALETTE)
png_set_expand(png_ptr);
if (color_type_ == PNG_COLOR_TYPE_GRAY && bit_depth_ < 8)
png_set_expand(png_ptr);
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_expand(png_ptr);
if (bit_depth_ == 16)
png_set_strip_16(png_ptr);
if (color_type_ == PNG_COLOR_TYPE_GRAY ||
color_type_ == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
// quick hack -- only work in >=libpng 1.2.7
png_set_add_alpha(png_ptr,0xff,PNG_FILLER_AFTER); //rgba
double gamma;
if (png_get_gAMA(png_ptr, info_ptr, &gamma))
png_set_gamma(png_ptr, 2.2, gamma);
if (x0 == 0 && y0 == 0 && image.width() >= width_ && image.height() >= height_)
{
if (png_get_interlace_type(png_ptr,info_ptr) == PNG_INTERLACE_ADAM7)
{
png_set_interlace_handling(png_ptr); // FIXME: libpng bug?
// according to docs png_read_image
// "..automatically handles interlacing,
// so you don't need to call png_set_interlace_handling()"
}
png_read_update_info(png_ptr, info_ptr);
// we can read whole image at once
// alloc row pointers
boost::scoped_array<png_byte*> rows(new png_bytep[height_]);
for (unsigned i=0; i<height_; ++i)
rows[i] = (png_bytep)image.getRow(i);
png_read_image(png_ptr, rows.get());
}
else
{
png_read_update_info(png_ptr, info_ptr);
unsigned w=std::min(unsigned(image.width()),width_);
unsigned h=std::min(unsigned(image.height()),height_);
unsigned rowbytes=png_get_rowbytes(png_ptr, info_ptr);
boost::scoped_array<png_byte> row(new png_byte[rowbytes]);
//START read image rows
for (unsigned i=0;i<height_;++i)
{
png_read_row(png_ptr,row.get(),0);
if (i>=y0 && i<h)
{
image.setRow(i-y0,reinterpret_cast<unsigned*>(&row[x0]),w);
}
}
//END
}
png_read_end(png_ptr,0);
png_destroy_read_struct(&png_ptr, &info_ptr,0);
fclose(fp);
}
}