img_png.c

It is extension program for SDL to display images other than bmp, but all the other formats.

/*
    SDL_image:  An example image loading library for use with SDL
    Copyright (C) 1997-2006 Sam Lantinga

    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

    Sam Lantinga
    [e-mail]
*/

/* This is a PNG image file loading framework */

#include <stdlib.h>
#include <stdio.h>

#include "SDL_image.h"

#ifdef LOAD_PNG

/*=============================================================================
        File: SDL_png.c
     Purpose: A PNG loader and saver for the SDL library      
    Revision: 
  Created by: Philippe Lavoie          (2 November 1998)
              [e-mail]
 Modified by: 

 Copyright notice:
          Copyright (C) 1998 Philippe Lavoie
 
          This library is free software; you can redistribute it and/or
          modify it under the terms of the GNU Library General Public
          License as published by the Free Software Foundation; either
          version 2 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
          Library General Public License for more details.
 
          You should have received a copy of the GNU Library General Public
          License along with this library; if not, write to the Free
          Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    Comments: The load and save routine are basically the ones you can find
             in the example.c file from the libpng distribution.

  Changes:
    5/17/99 - Modified to use the new SDL data sources - Sam Lantinga

=============================================================================*/

#include "SDL_endian.h"

#ifdef macintosh
#define MACOS
#endif
#include <png.h>


static struct {
	int loaded;
	void *handle;
	png_infop (*png_create_info_struct) (png_structp png_ptr);
	png_structp (*png_create_read_struct) (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn);
	void (*png_destroy_read_struct) (png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr);
	png_uint_32 (*png_get_IHDR) (png_structp png_ptr, png_infop info_ptr, png_uint_32 *width, png_uint_32 *height, int *bit_depth, int *color_type, int *interlace_method, int *compression_method, int *filter_method);
	png_voidp (*png_get_io_ptr) (png_structp png_ptr);
	png_uint_32 (*png_get_tRNS) (png_structp png_ptr, png_infop info_ptr, png_bytep *trans, int *num_trans, png_color_16p *trans_values);
	png_uint_32 (*png_get_valid) (png_structp png_ptr, png_infop info_ptr, png_uint_32 flag);
	void (*png_read_image) (png_structp png_ptr, png_bytepp image);
	void (*png_read_info) (png_structp png_ptr, png_infop info_ptr);
	void (*png_read_update_info) (png_structp png_ptr, png_infop info_ptr);
	void (*png_set_expand) (png_structp png_ptr);
	void (*png_set_gray_to_rgb) (png_structp png_ptr);
	void (*png_set_packing) (png_structp png_ptr);
	void (*png_set_read_fn) (png_structp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn);
	void (*png_set_strip_16) (png_structp png_ptr);
	int (*png_sig_cmp) (png_bytep sig, png_size_t start, png_size_t num_to_check);
} lib;

#ifdef LOAD_PNG_DYNAMIC
int IMG_InitPNG()
{
	if ( lib.loaded == 0 ) {
		lib.handle = SDL_LoadObject(LOAD_PNG_DYNAMIC);
		if ( lib.handle == NULL ) {
			return -1;
		}
		lib.png_create_info_struct =
			(png_infop (*) (png_structp))
			SDL_LoadFunction(lib.handle, "png_create_info_struct");
		if ( lib.png_create_info_struct == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_create_read_struct =
			(png_structp (*) (png_const_charp, png_voidp, png_error_ptr, png_error_ptr))
			SDL_LoadFunction(lib.handle, "png_create_read_struct");
		if ( lib.png_create_read_struct == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_destroy_read_struct =
			(void (*) (png_structpp, png_infopp, png_infopp))
			SDL_LoadFunction(lib.handle, "png_destroy_read_struct");
		if ( lib.png_destroy_read_struct == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_get_IHDR =
			(png_uint_32 (*) (png_structp, png_infop, png_uint_32 *, png_uint_32 *, int *, int *, int *, int *, int *))
			SDL_LoadFunction(lib.handle, "png_get_IHDR");
		if ( lib.png_get_IHDR == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_get_io_ptr =
			(png_voidp (*) (png_structp))
			SDL_LoadFunction(lib.handle, "png_get_io_ptr");
		if ( lib.png_get_io_ptr == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_get_tRNS =
			(png_uint_32 (*) (png_structp, png_infop, png_bytep *, int *, png_color_16p *))
			SDL_LoadFunction(lib.handle, "png_get_tRNS");
		if ( lib.png_get_tRNS == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_get_valid =
			(png_uint_32 (*) (png_structp, png_infop, png_uint_32))
			SDL_LoadFunction(lib.handle, "png_get_valid");
		if ( lib.png_get_valid == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_read_image =
			(void (*) (png_structp, png_bytepp))
			SDL_LoadFunction(lib.handle, "png_read_image");
		if ( lib.png_read_image == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_read_info =
			(void (*) (png_structp, png_infop))
			SDL_LoadFunction(lib.handle, "png_read_info");
		if ( lib.png_read_info == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_read_update_info =
			(void (*) (png_structp, png_infop))
			SDL_LoadFunction(lib.handle, "png_read_update_info");
		if ( lib.png_read_update_info == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_set_expand =
			(void (*) (png_structp))
			SDL_LoadFunction(lib.handle, "png_set_expand");
		if ( lib.png_set_expand == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_set_gray_to_rgb =
			(void (*) (png_structp))
			SDL_LoadFunction(lib.handle, "png_set_gray_to_rgb");
		if ( lib.png_set_gray_to_rgb == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_set_packing =
			(void (*) (png_structp))
			SDL_LoadFunction(lib.handle, "png_set_packing");
		if ( lib.png_set_packing == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_set_read_fn =
			(void (*) (png_structp, png_voidp, png_rw_ptr))
			SDL_LoadFunction(lib.handle, "png_set_read_fn");
		if ( lib.png_set_read_fn == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_set_strip_16 =
			(void (*) (png_structp))
			SDL_LoadFunction(lib.handle, "png_set_strip_16");
		if ( lib.png_set_strip_16 == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
		lib.png_sig_cmp =
			(int (*) (png_bytep, png_size_t, png_size_t))
			SDL_LoadFunction(lib.handle, "png_sig_cmp");
		if ( lib.png_sig_cmp == NULL ) {
			SDL_UnloadObject(lib.handle);
			return -1;
		}
	}
	++lib.loaded;

	return 0;
}
void IMG_QuitPNG()
{
	if ( lib.loaded == 0 ) {
		return;
	}
	if ( lib.loaded == 1 ) {
		SDL_UnloadObject(lib.handle);
	}
	--lib.loaded;
}
#else
int IMG_InitPNG()
{
	if ( lib.loaded == 0 ) {
		lib.png_create_info_struct = png_create_info_struct;
		lib.png_create_read_struct = png_create_read_struct;
		lib.png_destroy_read_struct = png_destroy_read_struct;
		lib.png_get_IHDR = png_get_IHDR;
		lib.png_get_io_ptr = png_get_io_ptr;
		lib.png_get_tRNS = png_get_tRNS;
		lib.png_get_valid = png_get_valid;
		lib.png_read_image = png_read_image;
		lib.png_read_info = png_read_info;
		lib.png_read_update_info = png_read_update_info;
		lib.png_set_expand = png_set_expand;
		lib.png_set_gray_to_rgb = png_set_gray_to_rgb;
		lib.png_set_packing = png_set_packing;
		lib.png_set_read_fn = png_set_read_fn;
		lib.png_set_strip_16 = png_set_strip_16;
		lib.png_sig_cmp = png_sig_cmp;
	}
	++lib.loaded;

	return 0;
}
void IMG_QuitPNG()
{
	if ( lib.loaded == 0 ) {
		return;
	}
	if ( lib.loaded == 1 ) {
	}
	--lib.loaded;
}