IMG.c
author Sam Lantinga <slouken@libsdl.org>
Fri, 14 Dec 2001 13:02:16 +0000
changeset 53 96b084473b47
parent 50 754bff7e03aa
child 62 dbc075a7e0b1
permissions -rw-r--r--
*** empty log message ***
     1 /*
     2     SDL_image:  An example image loading library for use with SDL
     3     Copyright (C) 1999, 2000, 2001  Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Library General Public
     7     License as published by the Free Software Foundation; either
     8     version 2 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Library General Public License for more details.
    14 
    15     You should have received a copy of the GNU Library General Public
    16     License along with this library; if not, write to the Free
    17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 
    23 /* $Id$ */
    24 
    25 /* A simple library to load images of various formats as SDL surfaces */
    26 
    27 #include <stdio.h>
    28 #include <string.h>
    29 #include <ctype.h>
    30 
    31 #include "SDL_image.h"
    32 
    33 #define ARRAYSIZE(a) (sizeof(a) / sizeof((a)[0]))
    34 
    35 /* Table of image detection and loading functions */
    36 static struct {
    37 	char *type;
    38 	int (*is)(SDL_RWops *src);
    39 	SDL_Surface *(*load)(SDL_RWops *src);
    40 } supported[] = {
    41 	/* keep magicless formats first */
    42 	{ "TGA", 0,         IMG_LoadTGA_RW },
    43 	{ "BMP", IMG_isBMP, IMG_LoadBMP_RW },
    44 	{ "PNM", IMG_isPNM, IMG_LoadPNM_RW }, /* P[BGP]M share code */
    45 	{ "XPM", IMG_isXPM, IMG_LoadXPM_RW },
    46 	{ "XCF", IMG_isXCF, IMG_LoadXCF_RW },
    47 	{ "PCX", IMG_isPCX, IMG_LoadPCX_RW },
    48 	{ "GIF", IMG_isGIF, IMG_LoadGIF_RW },
    49 	{ "JPG", IMG_isJPG, IMG_LoadJPG_RW },
    50 	{ "TIF", IMG_isTIF, IMG_LoadTIF_RW },
    51 	{ "LBM", IMG_isLBM, IMG_LoadLBM_RW },
    52 	{ "PNG", IMG_isPNG, IMG_LoadPNG_RW }
    53 };
    54 
    55 /* Load an image from a file */
    56 SDL_Surface *IMG_Load(const char *file)
    57 {
    58     SDL_RWops *src = SDL_RWFromFile(file, "rb");
    59     char *ext = strrchr(file, '.');
    60     if(ext)
    61 	ext++;
    62     return IMG_LoadTyped_RW(src, 1, ext);
    63 }
    64 
    65 /* Load an image from an SDL datasource (for compatibility) */
    66 SDL_Surface *IMG_Load_RW(SDL_RWops *src, int freesrc)
    67 {
    68     return IMG_LoadTyped_RW(src, freesrc, NULL);
    69 }
    70 
    71 /* Portable case-insensitive string compare function */
    72 static int IMG_string_equals(const char *str1, const char *str2)
    73 {
    74 	while ( *str1 && *str2 ) {
    75 		if ( toupper((unsigned char)*str1) !=
    76 		     toupper((unsigned char)*str2) )
    77 			break;
    78 		++str1;
    79 		++str2;
    80 	}
    81 	return (!*str1 && !*str2);
    82 }
    83 
    84 /* Load an image from an SDL datasource, optionally specifying the type */
    85 SDL_Surface *IMG_LoadTyped_RW(SDL_RWops *src, int freesrc, char *type)
    86 {
    87 	int i, start;
    88 	SDL_Surface *image;
    89 
    90 	/* Make sure there is something to do.. */
    91 	if ( src == NULL ) {
    92 		return(NULL);
    93 	}
    94 
    95 	/* See whether or not this data source can handle seeking */
    96 	if ( SDL_RWseek(src, 0, SEEK_CUR) < 0 ) {
    97 		IMG_SetError("Can't seek in this data source");
    98 		return(NULL);
    99 	}
   100 
   101 	/* Detect the type of image being loaded */
   102 	start = SDL_RWtell(src);
   103 	image = NULL;
   104 	for ( i=0; i < ARRAYSIZE(supported); ++i ) {
   105 	        if( (supported[i].is
   106 		     && (SDL_RWseek(src, start, SEEK_SET),
   107 			 supported[i].is(src)))
   108 		    || (type && IMG_string_equals(type, supported[i].type))) {
   109 #ifdef DEBUG_IMGLIB
   110 			fprintf(stderr, "IMGLIB: Loading image as %s\n",
   111 							supported[i].type);
   112 #endif
   113 			SDL_RWseek(src, start, SEEK_SET);
   114 			image = supported[i].load(src);
   115 			break;
   116 		}
   117 	}
   118 
   119 	/* Clean up, check for errors, and return */
   120 	if ( freesrc ) {
   121 		SDL_RWclose(src);
   122 	}
   123 	if ( i == ARRAYSIZE(supported) ) {
   124 		IMG_SetError("Unsupported image format");
   125 	}
   126 	return(image);
   127 }
   128 
   129 /* Invert the alpha of a surface for use with OpenGL
   130    This function is a no-op and only kept for backwards compatibility.
   131  */
   132 int IMG_InvertAlpha(int on)
   133 {
   134     return 1;
   135 }