/* A code fragment that you call as you receive blocks of data */
int inlinepng_process_data(png_bytep buffer, png_uint_32 length) {
if(Gpng_ptr == 0) {
png_cleanup();
return 0;
};
if (setjmp(png_jmpbuf(Gpng_ptr))) {
png_destroy_read_struct(&Gpng_ptr, &Ginfo_ptr, (png_infopp)NULL);
return 1;
}
png_process_data(Gpng_ptr, Ginfo_ptr, buffer, length);
return 0;
}
void
png_output ()
{
compute_positions ();
scan_map ();
do_dots ();
if (num_colors > 256) {
png_truecolor_setup ();
render (png_truecolor_row);
png_truecolor_cleanup (stdout);
} else {
png_setup ();
render (png_row);
png_cleanup (stdout);
}
}
void write( Image& img, const char* filename ) {
if ( !( img.get_width() > 0 && img.get_height() > 0 && img.get_num_channels() > 0 ) ) {
throw std::exception( "This is not a valid image to write." );
}
FILE* fp = fopen( filename, "wb" );
if ( !fp ) {
throw std::exception( "Failed to open file." );
}
boost::shared_ptr<void> fp_cleanup( static_cast<void*>(0), boost::bind( fclose, fp ) );
png_structp png_ptr = png_create_write_struct( PNG_LIBPNG_VER_STRING, NULL, NULL, NULL );
if (!png_ptr) {
throw std::exception( "png_create_write_struct failed." );
}
png_infop info_ptr = 0;
boost::shared_ptr<void> png_cleanup( static_cast<void*>(0), boost::bind( png_destroy_write_struct, &png_ptr, &info_ptr ) );
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
throw std::exception( "png_create_info_struct failed." );
}
if ( setjmp(png_jmpbuf(png_ptr)) ) {
throw std::exception( "libpng returned an error." );
}
png_init_io(png_ptr, fp);
// optional: call png_set_filter to control compression
// fill png_info structure
typedef boost::scoped_array< Image::channel* > Channel_array;
Channel_array row_pointers( new Image::channel* [ img.get_height() ] );
for ( int row = 0; row < img.get_height(); ++row ) {
row_pointers[ row ] = img.get_row_ptr( row );
}
png_set_rows( png_ptr, info_ptr, row_pointers.get() );
png_set_IHDR(
png_ptr,
info_ptr,
img.get_width(),
img.get_height(),
8,
PNG_COLOR_TYPE_RGB,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT );
png_write_png(
png_ptr,
info_ptr,
PNG_TRANSFORM_IDENTITY,
NULL );
}
void read( Image& img, const char* file_name ) {
// TODO: Use shared_ptr to execute fclose() etc. when exiting scope.
// open file
FILE *fp = fopen(file_name, "rb");
if (!fp) {
throw std::exception("Failed to open file.");
}
boost::shared_ptr<void> fp_cleanup( static_cast<void*>(0), boost::bind( fclose, fp ) );
const int PNG_BYTES_TO_CHECK = 4;
png_byte header[PNG_BYTES_TO_CHECK];
fread(header, 1, PNG_BYTES_TO_CHECK, fp);
const bool is_png = !png_sig_cmp(header, 0, PNG_BYTES_TO_CHECK);
if (!is_png) {
throw std::exception("File is not a valid PNG file.");
}
// setup PNG structs
png_structp png_ptr = png_create_read_struct( PNG_LIBPNG_VER_STRING, 0, 0, 0);
if (!png_ptr) {
throw std::exception("png_create_read_struct failed.");
}
png_infop info_ptr = 0;
png_infop end_info = 0;
boost::shared_ptr<void> png_cleanup( static_cast<void*>(0), boost::bind( png_destroy_read_struct, &png_ptr, &info_ptr, &end_info ) );
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
throw std::exception("png_create_info_struct failed.");
}
end_info = png_create_info_struct(png_ptr);
if (!end_info) {
throw std::exception("png_create_info_struct failed.");
}
// TODO Remove setjmp
if (setjmp(png_jmpbuf(png_ptr))) {
throw std::exception("Failed to read PNG-image.");
}
png_init_io(png_ptr, fp);
png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK);
png_read_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL);
const png_bytep* row_pointers = png_get_rows(png_ptr, info_ptr);
// Assert we are making correct assumptions about PNG lib.
assert( info_ptr->rowbytes == info_ptr->channels * info_ptr->width );
Image img_tmp( info_ptr->width, info_ptr->height, info_ptr->channels, row_pointers );
img.swap( img_tmp );
}
void end_callback(png_structp png_ptr, png_infop info) {
png_cleanup();
}
