IMG.c
author Sam Lantinga <slouken@libsdl.org>
Wed, 23 Jul 2003 05:08:43 +0000
changeset 89 9a1b32277af8
parent 78 337263a596dc
child 95 7fcb46931afc
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 const SDL_version *IMG_Linked_Version(void)
    56 {
    57 	static SDL_version linked_version;
    58 	SDL_IMAGE_VERSION(&linked_version);
    59 	return(&linked_version);
    60 }
    61 
    62 /* Load an image from a file */
    63 SDL_Surface *IMG_Load(const char *file)
    64 {
    65     SDL_RWops *src = SDL_RWFromFile(file, "rb");
    66     char *ext = strrchr(file, '.');
    67     if(ext)
    68 	ext++;
    69     return IMG_LoadTyped_RW(src, 1, ext);
    70 }
    71 
    72 /* Load an image from an SDL datasource (for compatibility) */
    73 SDL_Surface *IMG_Load_RW(SDL_RWops *src, int freesrc)
    74 {
    75     return IMG_LoadTyped_RW(src, freesrc, NULL);
    76 }
    77 
    78 /* Portable case-insensitive string compare function */
    79 static int IMG_string_equals(const char *str1, const char *str2)
    80 {
    81 	while ( *str1 && *str2 ) {
    82 		if ( toupper((unsigned char)*str1) !=
    83 		     toupper((unsigned char)*str2) )
    84 			break;
    85 		++str1;
    86 		++str2;
    87 	}
    88 	return (!*str1 && !*str2);
    89 }
    90 
    91 /* Load an image from an SDL datasource, optionally specifying the type */
    92 SDL_Surface *IMG_LoadTyped_RW(SDL_RWops *src, int freesrc, char *type)
    93 {
    94 	int i, start;
    95 	SDL_Surface *image;
    96 
    97 	/* Make sure there is something to do.. */
    98 	if ( src == NULL ) {
    99 		return(NULL);
   100 	}
   101 
   102 	/* See whether or not this data source can handle seeking */
   103 	if ( SDL_RWseek(src, 0, SEEK_CUR) < 0 ) {
   104 		IMG_SetError("Can't seek in this data source");
   105 		if(freesrc)
   106 			SDL_RWclose(src);
   107 		return(NULL);
   108 	}
   109 
   110 	/* Detect the type of image being loaded */
   111 	start = SDL_RWtell(src);
   112 	image = NULL;
   113 	for ( i=0; i < ARRAYSIZE(supported); ++i ) {
   114 		if(supported[i].is) {
   115 			SDL_RWseek(src, start, SEEK_SET);
   116 			if(!supported[i].is(src))
   117 				continue;
   118 		} else {
   119 			/* magicless format */
   120 			if(!type
   121 			   || !IMG_string_equals(type, supported[i].type))
   122 				continue;
   123 		}
   124 #ifdef DEBUG_IMGLIB
   125 		fprintf(stderr, "IMGLIB: Loading image as %s\n",
   126 			supported[i].type);
   127 #endif
   128 		SDL_RWseek(src, start, SEEK_SET);
   129 		image = supported[i].load(src);
   130 		if(freesrc)
   131 			SDL_RWclose(src);
   132 		return image;
   133 	}
   134 
   135 	if ( freesrc ) {
   136 		SDL_RWclose(src);
   137 	}
   138 	IMG_SetError("Unsupported image format");
   139 	return NULL;
   140 }
   141 
   142 /* Invert the alpha of a surface for use with OpenGL
   143    This function is a no-op and only kept for backwards compatibility.
   144  */
   145 int IMG_InvertAlpha(int on)
   146 {
   147     return 1;
   148 }