/*    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    slouken@libsdl.org*//* A simple library to load images of various formats as SDL surfaces */#include <stdio.h>#include <string.h>#include <ctype.h>#include "SDL_image.h"#define ARRAYSIZE(a) (sizeof(a) / sizeof((a)[0]))/* Table of image detection and loading functions */static struct {	char *type;	int (SDLCALL *is)(SDL_RWops *src);	SDL_Surface *(SDLCALL *load)(SDL_RWops *src);} supported[] = {	/* keep magicless formats first */	{ "TGA", NULL,      IMG_LoadTGA_RW },	{ "BMP", IMG_isBMP, IMG_LoadBMP_RW },	{ "GIF", IMG_isGIF, IMG_LoadGIF_RW },	{ "JPG", IMG_isJPG, IMG_LoadJPG_RW },	{ "LBM", IMG_isLBM, IMG_LoadLBM_RW },	{ "PCX", IMG_isPCX, IMG_LoadPCX_RW },	{ "PNG", IMG_isPNG, IMG_LoadPNG_RW },	{ "PNM", IMG_isPNM, IMG_LoadPNM_RW }, /* P[BGP]M share code */	{ "TIF", IMG_isTIF, IMG_LoadTIF_RW },	{ "XCF", IMG_isXCF, IMG_LoadXCF_RW },	{ "XPM", IMG_isXPM, IMG_LoadXPM_RW },	{ "XV",  IMG_isXV,  IMG_LoadXV_RW  }};const SDL_version *IMG_Linked_Version(void){	static SDL_version linked_version;	SDL_IMAGE_VERSION(&linked_version);	return(&linked_version);}/* Load an image from a file */SDL_Surface *IMG_Load(const char *file){    SDL_RWops *src = SDL_RWFromFile(file, "rb");    char *ext = strrchr(file, '.');    if(ext) {        ext++;    }    if(!src) {        /* The error message has been set in SDL_RWFromFile */        return NULL;    }    return IMG_LoadTyped_RW(src, 1, ext);}/* Load an image from an SDL datasource (for compatibility) */SDL_Surface *IMG_Load_RW(SDL_RWops *src, int freesrc){    return IMG_LoadTyped_RW(src, freesrc, NULL);}/* Portable case-insensitive string compare function */static int IMG_string_equals(const char *str1, const char *str2){	while ( *str1 && *str2 ) {		if ( toupper((unsigned char)*str1) !=		     toupper((unsigned char)*str2) )			break;		++str1;		++str2;	}	return (!*str1 && !*str2);}/* Load an image from an SDL datasource, optionally specifying the type */SDL_Surface *IMG_LoadTyped_RW(SDL_RWops *src, int freesrc, char *type){	int i;	SDL_Surface *image;	/* Make sure there is something to do.. */	if ( src == NULL ) {		IMG_SetError("Passed a NULL data source");		return(NULL);	}	/* See whether or not this data source can handle seeking */	if ( SDL_RWseek(src, 0, SEEK_CUR) < 0 ) {		IMG_SetError("Can't seek in this data source");		if(freesrc)			SDL_RWclose(src);		return(NULL);	}	/* Detect the type of image being loaded */	image = NULL;	for ( i=0; i < ARRAYSIZE(supported); ++i ) {		if(supported[i].is) {			if(!supported[i].is(src))				continue;		} else {			/* magicless format */			if(!type			   || !IMG_string_equals(type, supported[i].type))				continue;		}#ifdef DEBUG_IMGLIB		fprintf(stderr, "IMGLIB: Loading image as %s\n",			supported[i].type);#endif		image = supported[i].load(src);		if(freesrc)			SDL_RWclose(src);		return image;	}	if ( freesrc ) {		SDL_RWclose(src);	}	IMG_SetError("Unsupported image format");	return NULL;}/* Invert the alpha of a surface for use with OpenGL   This function is a no-op and only kept for backwards compatibility. */int IMG_InvertAlpha(int on){    return 1;}