/*

    SDL_image:  An example image loading library for use with SDL

    Copyright (C) 1997-2009 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

    slouken@libsdl.org

*/

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

#include <stdlib.h>

#include <stdio.h>

#include "SDL_image.h"

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

        File: SDL_png.c

     Purpose: A PNG loader and saver for the SDL library      

    Revision: 

  Created by: Philippe Lavoie          (2 November 1998)

              lavoie@zeus.genie.uottawa.ca

 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;

}

#endif /* LOAD_PNG_DYNAMIC */

/* See if an image is contained in a data source */

int IMG_isPNG(SDL_RWops *src)

{

	int start;

	int is_PNG;

	Uint8 magic[4];

	if ( !src )

		return 0;

	start = SDL_RWtell(src);

	is_PNG = 0;

	if ( SDL_RWread(src, magic, 1, sizeof(magic)) == sizeof(magic) ) {

                if ( magic[0] == 0x89 &&

                     magic[1] == 'P' &&

                     magic[2] == 'N' &&

                     magic[3] == 'G' ) {

			is_PNG = 1;

		}

	}

	SDL_RWseek(src, start, RW_SEEK_SET);

	return(is_PNG);

}

/* Load a PNG type image from an SDL datasource */

static void png_read_data(png_structp ctx, png_bytep area, png_size_t size)

{

	SDL_RWops *src;

	src = (SDL_RWops *)lib.png_get_io_ptr(ctx);

	SDL_RWread(src, area, size, 1);

}

SDL_Surface *IMG_LoadPNG_RW(SDL_RWops *src)

{

	int start;

	const char *error;

	SDL_Surface *volatile surface;

	png_structp png_ptr;

	png_infop info_ptr;

	png_uint_32 width, height;

	int bit_depth, color_type, interlace_type;

	Uint32 Rmask;

	Uint32 Gmask;

	Uint32 Bmask;

	Uint32 Amask;

	SDL_Palette *palette;

	png_bytep *volatile row_pointers;

	int row, i;

	volatile int ckey = -1;

	png_color_16 *transv;

	if ( !src ) {

		/* The error message has been set in SDL_RWFromFile */

		return NULL;

	}

	start = SDL_RWtell(src);

	if ( !IMG_Init(IMG_INIT_PNG) ) {

		return NULL;

	}

	/* Initialize the data we will clean up when we're done */

	error = NULL;

	png_ptr = NULL; info_ptr = NULL; row_pointers = NULL; surface = NULL;

	/* Create the PNG loading context structure */

	png_ptr = lib.png_create_read_struct(PNG_LIBPNG_VER_STRING,

					  NULL,NULL,NULL);

	if (png_ptr == NULL){

		error = "Couldn't allocate memory for PNG file or incompatible PNG dll";

		goto done;

	}

	 /* Allocate/initialize the memory for image information.  REQUIRED. */

	info_ptr = lib.png_create_info_struct(png_ptr);

	if (info_ptr == NULL) {

		error = "Couldn't create image information for PNG file";

		goto done;

	}

	/* Set error handling if you are using setjmp/longjmp method (this is

	 * the normal method of doing things with libpng).  REQUIRED unless you

	 * set up your own error handlers in png_create_read_struct() earlier.

	 */

	if ( setjmp(png_ptr->jmpbuf) ) {

		error = "Error reading the PNG file.";

		goto done;

	}

	/* Set up the input control */

	lib.png_set_read_fn(png_ptr, src, png_read_data);

	/* Read PNG header info */

	lib.png_read_info(png_ptr, info_ptr);

	lib.png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth,

			&color_type, &interlace_type, NULL, NULL);

	/* tell libpng to strip 16 bit/color files down to 8 bits/color */

	lib.png_set_strip_16(png_ptr) ;

	/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single

	 * byte into separate bytes (useful for paletted and grayscale images).

	 */

	lib.png_set_packing(png_ptr);

	/* scale greyscale values to the range 0..255 */

	if(color_type == PNG_COLOR_TYPE_GRAY)

		lib.png_set_expand(png_ptr);

	/* For images with a single "transparent colour", set colour key;

	   if more than one index has transparency, or if partially transparent

	   entries exist, use full alpha channel */

	if (lib.png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {

	        int num_trans;

		Uint8 *trans;

		lib.png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,

			     &transv);

		if(color_type == PNG_COLOR_TYPE_PALETTE) {

		    /* Check if all tRNS entries are opaque except one */

		    int t = -1;

		    for(i = 0; i < num_trans; i++)

			if(trans[i] == 0) {

			    if(t >= 0)

				break;

			    t = i;

			} else if(trans[i] != 255)

			    break;

		    if(i == num_trans) {

			/* exactly one transparent index */

			ckey = t;

		    } else {

			/* more than one transparent index, or translucency */

			lib.png_set_expand(png_ptr);

		    }

		} else

		    ckey = 0; /* actual value will be set later */

	}

	if ( color_type == PNG_COLOR_TYPE_GRAY_ALPHA )

		lib.png_set_gray_to_rgb(png_ptr);

	lib.png_read_update_info(png_ptr, info_ptr);

	lib.png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth,

			&color_type, &interlace_type, NULL, NULL);

	/* Allocate the SDL surface to hold the image */

	Rmask = Gmask = Bmask = Amask = 0 ; 

	if ( color_type != PNG_COLOR_TYPE_PALETTE ) {

		if ( SDL_BYTEORDER == SDL_LIL_ENDIAN ) {

			Rmask = 0x000000FF;

			Gmask = 0x0000FF00;

			Bmask = 0x00FF0000;

			Amask = (info_ptr->channels == 4) ? 0xFF000000 : 0;

		} else {

		        int s = (info_ptr->channels == 4) ? 0 : 8;

			Rmask = 0xFF000000 >> s;

			Gmask = 0x00FF0000 >> s;

			Bmask = 0x0000FF00 >> s;

			Amask = 0x000000FF >> s;

		}

	}

	surface = SDL_AllocSurface(SDL_SWSURFACE, width, height,

			bit_depth*info_ptr->channels, Rmask,Gmask,Bmask,Amask);

	if ( surface == NULL ) {

		error = "Out of memory";

		goto done;

	}

	if(ckey != -1) {

	        if(color_type != PNG_COLOR_TYPE_PALETTE)

			/* FIXME: Should these be truncated or shifted down? */

		        ckey = SDL_MapRGB(surface->format,

			                 (Uint8)transv->red,

			                 (Uint8)transv->green,

			                 (Uint8)transv->blue);

	        SDL_SetColorKey(surface, SDL_SRCCOLORKEY, ckey);

	}

	/* Create the array of pointers to image data */

	row_pointers = (png_bytep*) malloc(sizeof(png_bytep)*height);

	if ( (row_pointers == NULL) ) {

		error = "Out of memory";

		goto done;

	}

	for (row = 0; row < (int)height; row++) {

		row_pointers[row] = (png_bytep)

				(Uint8 *)surface->pixels + row*surface->pitch;

	}

	/* Read the entire image in one go */

	lib.png_read_image(png_ptr, row_pointers);

	/* and we're done!  (png_read_end() can be omitted if no processing of

	 * post-IDAT text/time/etc. is desired)

	 * In some cases it can't read PNG's created by some popular programs (ACDSEE),

	 * we do not want to process comments, so we omit png_read_end

	lib.png_read_end(png_ptr, info_ptr);

	*/

	/* Load the palette, if any */

	palette = surface->format->palette;

	if ( palette ) {

	    if(color_type == PNG_COLOR_TYPE_GRAY) {

			palette->ncolors = 256;

			for(i = 0; i < 256; i++) {

				palette->colors[i].r = i;

				palette->colors[i].g = i;

				palette->colors[i].b = i;

			}

		} else if (info_ptr->num_palette > 0 ) {

			palette->ncolors = info_ptr->num_palette; 

			for( i=0; i<info_ptr->num_palette; ++i ) {

				palette->colors[i].b = info_ptr->palette[i].blue;

				palette->colors[i].g = info_ptr->palette[i].green;

				palette->colors[i].r = info_ptr->palette[i].red;

			}

	    }

	}

done:	/* Clean up and return */

	if ( png_ptr ) {

		lib.png_destroy_read_struct(&png_ptr,

		                        info_ptr ? &info_ptr : (png_infopp)0,

								(png_infopp)0);

	}

	if ( row_pointers ) {

		free(row_pointers);

	}

	if ( error ) {

		SDL_RWseek(src, start, RW_SEEK_SET);

		if ( surface ) {

			SDL_FreeSurface(surface);

			surface = NULL;

		}

		IMG_SetError(error);

	}

	return(surface); 

}