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IMG.c
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IMG.c
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/*
IMGLIB: An example image loading library for use with SDL
Copyright (C) 1999 Sam Lantinga
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
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
5635-34 Springhouse Dr.
Pleasanton, CA 94588 (USA)
slouken@devolution.com
*/
/* 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 (*is)(SDL_RWops *src);
SDL_Surface *(*load)(SDL_RWops *src);
} supported[] = {
/* keep magicless formats first (denoted by is==NULL) */
{ "TGA", NULL, IMG_LoadTGA_RW },
{ "BMP", IMG_isBMP, IMG_LoadBMP_RW },
{ "PPM", IMG_isPPM, IMG_LoadPPM_RW },
{ "XPM", IMG_isXPM, IMG_LoadXPM_RW },
{ "PCX", IMG_isPCX, IMG_LoadPCX_RW },
{ "GIF", IMG_isGIF, IMG_LoadGIF_RW },
{ "JPG", IMG_isJPG, IMG_LoadJPG_RW },
{ "TIF", IMG_isTIF, IMG_LoadTIF_RW },
{ "PNG", IMG_isPNG, IMG_LoadPNG_RW }
};
/* 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++;
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 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, start;
SDL_Surface *image;
/* Make sure there is something to do.. */
if ( src == NULL ) {
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");
return(NULL);
}
/* Detect the type of image being loaded */
start = SDL_RWtell(src);
image = NULL;
for ( i=0; i < ARRAYSIZE(supported) && !image; ++i ) {
if( (supported[i].is
&& (SDL_RWseek(src, start, SEEK_SET),
supported[i].is(src)))
|| (type && string_equals(type, supported[i].type))) {
#ifdef DEBUG_IMGLIB
fprintf(stderr, "IMGLIB: Loading image as %s\n",
supported[i].type);
#endif
SDL_RWseek(src, start, SEEK_SET);
image = supported[i].load(src);
break;
}
}
/* Clean up, check for errors, and return */
if ( freesrc ) {
SDL_RWclose(src);
}
if ( image == NULL ) {
IMG_SetError("Unsupported image format");
}
return(image);
}
/* 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;
}