IMG.c
author Sam Lantinga <slouken@libsdl.org>
Thu, 20 Jun 2002 17:06:38 +0000
changeset 71 e2eb6980be07
parent 62 dbc075a7e0b1
child 78 337263a596dc
permissions -rw-r--r--
Pete Shinners - Thu Jun 20 10:05:54 PDT 2002
* The JPEG loader can now load EXIF format JPEG images
slouken@0
     1
/*
slouken@53
     2
    SDL_image:  An example image loading library for use with SDL
slouken@53
     3
    Copyright (C) 1999, 2000, 2001  Sam Lantinga
slouken@0
     4
slouken@0
     5
    This library is free software; you can redistribute it and/or
slouken@0
     6
    modify it under the terms of the GNU Library General Public
slouken@0
     7
    License as published by the Free Software Foundation; either
slouken@0
     8
    version 2 of the License, or (at your option) any later version.
slouken@0
     9
slouken@0
    10
    This library is distributed in the hope that it will be useful,
slouken@0
    11
    but WITHOUT ANY WARRANTY; without even the implied warranty of
slouken@0
    12
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
slouken@0
    13
    Library General Public License for more details.
slouken@0
    14
slouken@0
    15
    You should have received a copy of the GNU Library General Public
slouken@0
    16
    License along with this library; if not, write to the Free
slouken@0
    17
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
slouken@0
    18
slouken@0
    19
    Sam Lantinga
slouken@53
    20
    slouken@libsdl.org
slouken@0
    21
*/
slouken@0
    22
slouken@53
    23
/* $Id$ */
slouken@53
    24
slouken@0
    25
/* A simple library to load images of various formats as SDL surfaces */
slouken@0
    26
slouken@0
    27
#include <stdio.h>
slouken@0
    28
#include <string.h>
slouken@0
    29
#include <ctype.h>
slouken@0
    30
slouken@0
    31
#include "SDL_image.h"
slouken@0
    32
slouken@7
    33
#define ARRAYSIZE(a) (sizeof(a) / sizeof((a)[0]))
slouken@7
    34
slouken@0
    35
/* Table of image detection and loading functions */
slouken@0
    36
static struct {
slouken@0
    37
	char *type;
slouken@0
    38
	int (*is)(SDL_RWops *src);
slouken@0
    39
	SDL_Surface *(*load)(SDL_RWops *src);
slouken@0
    40
} supported[] = {
slouken@24
    41
	/* keep magicless formats first */
slouken@24
    42
	{ "TGA", 0,         IMG_LoadTGA_RW },
slouken@0
    43
	{ "BMP", IMG_isBMP, IMG_LoadBMP_RW },
slouken@24
    44
	{ "PNM", IMG_isPNM, IMG_LoadPNM_RW }, /* P[BGP]M share code */
slouken@7
    45
	{ "XPM", IMG_isXPM, IMG_LoadXPM_RW },
slouken@26
    46
	{ "XCF", IMG_isXCF, IMG_LoadXCF_RW },
slouken@0
    47
	{ "PCX", IMG_isPCX, IMG_LoadPCX_RW },
slouken@0
    48
	{ "GIF", IMG_isGIF, IMG_LoadGIF_RW },
slouken@0
    49
	{ "JPG", IMG_isJPG, IMG_LoadJPG_RW },
slouken@0
    50
	{ "TIF", IMG_isTIF, IMG_LoadTIF_RW },
slouken@45
    51
	{ "LBM", IMG_isLBM, IMG_LoadLBM_RW },
slouken@7
    52
	{ "PNG", IMG_isPNG, IMG_LoadPNG_RW }
slouken@0
    53
};
slouken@0
    54
slouken@0
    55
/* Load an image from a file */
slouken@0
    56
SDL_Surface *IMG_Load(const char *file)
slouken@0
    57
{
slouken@0
    58
    SDL_RWops *src = SDL_RWFromFile(file, "rb");
slouken@0
    59
    char *ext = strrchr(file, '.');
slouken@0
    60
    if(ext)
slouken@0
    61
	ext++;
slouken@0
    62
    return IMG_LoadTyped_RW(src, 1, ext);
slouken@0
    63
}
slouken@0
    64
slouken@0
    65
/* Load an image from an SDL datasource (for compatibility) */
slouken@0
    66
SDL_Surface *IMG_Load_RW(SDL_RWops *src, int freesrc)
slouken@0
    67
{
slouken@0
    68
    return IMG_LoadTyped_RW(src, freesrc, NULL);
slouken@0
    69
}
slouken@0
    70
slouken@0
    71
/* Portable case-insensitive string compare function */
slouken@50
    72
static int IMG_string_equals(const char *str1, const char *str2)
slouken@0
    73
{
slouken@0
    74
	while ( *str1 && *str2 ) {
slouken@0
    75
		if ( toupper((unsigned char)*str1) !=
slouken@0
    76
		     toupper((unsigned char)*str2) )
slouken@0
    77
			break;
slouken@0
    78
		++str1;
slouken@0
    79
		++str2;
slouken@0
    80
	}
slouken@0
    81
	return (!*str1 && !*str2);
slouken@0
    82
}
slouken@0
    83
slouken@0
    84
/* Load an image from an SDL datasource, optionally specifying the type */
slouken@0
    85
SDL_Surface *IMG_LoadTyped_RW(SDL_RWops *src, int freesrc, char *type)
slouken@0
    86
{
slouken@0
    87
	int i, start;
slouken@0
    88
	SDL_Surface *image;
slouken@0
    89
slouken@0
    90
	/* Make sure there is something to do.. */
slouken@0
    91
	if ( src == NULL ) {
slouken@0
    92
		return(NULL);
slouken@0
    93
	}
slouken@0
    94
slouken@0
    95
	/* See whether or not this data source can handle seeking */
slouken@0
    96
	if ( SDL_RWseek(src, 0, SEEK_CUR) < 0 ) {
slouken@0
    97
		IMG_SetError("Can't seek in this data source");
slouken@0
    98
		return(NULL);
slouken@0
    99
	}
slouken@0
   100
slouken@0
   101
	/* Detect the type of image being loaded */
slouken@0
   102
	start = SDL_RWtell(src);
slouken@0
   103
	image = NULL;
slouken@11
   104
	for ( i=0; i < ARRAYSIZE(supported); ++i ) {
slouken@62
   105
		if(supported[i].is) {
slouken@62
   106
			SDL_RWseek(src, start, SEEK_SET);
slouken@62
   107
			if(!supported[i].is(src))
slouken@62
   108
				continue;
slouken@62
   109
		} else {
slouken@62
   110
			/* magicless format */
slouken@62
   111
			if(!type
slouken@62
   112
			   || !IMG_string_equals(type, supported[i].type))
slouken@62
   113
				continue;
slouken@62
   114
		}
slouken@0
   115
#ifdef DEBUG_IMGLIB
slouken@62
   116
		fprintf(stderr, "IMGLIB: Loading image as %s\n",
slouken@62
   117
			supported[i].type);
slouken@0
   118
#endif
slouken@62
   119
		SDL_RWseek(src, start, SEEK_SET);
slouken@62
   120
		image = supported[i].load(src);
slouken@62
   121
		if(freesrc)
slouken@62
   122
			SDL_RWclose(src);
slouken@62
   123
		return image;
slouken@0
   124
	}
slouken@0
   125
slouken@0
   126
	if ( freesrc ) {
slouken@0
   127
		SDL_RWclose(src);
slouken@0
   128
	}
slouken@62
   129
	IMG_SetError("Unsupported image format");
slouken@62
   130
	return NULL;
slouken@0
   131
}
slouken@0
   132
slouken@0
   133
/* Invert the alpha of a surface for use with OpenGL
slouken@4
   134
   This function is a no-op and only kept for backwards compatibility.
slouken@0
   135
 */
slouken@0
   136
int IMG_InvertAlpha(int on)
slouken@0
   137
{
slouken@4
   138
    return 1;
slouken@0
   139
}