1 /*

     2     SDL_image:  An example image loading library for use with SDL

     3     Copyright (C) 1997-2009 Sam Lantinga

     4 

     5     This library is free software; you can redistribute it and/or

     6     modify it under the terms of the GNU Lesser General Public

     7     License as published by the Free Software Foundation; either

     8     version 2.1 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     Lesser General Public License for more details.

    14 

    15     You should have received a copy of the GNU Lesser General Public

    16     License along with this library; if not, write to the Free Software

    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    18 

    19     Sam Lantinga

    20     slouken@libsdl.org

    21 */

    22 

    23 /* A simple library to load images of various formats as SDL surfaces */

    24 

    25 #include <stdio.h>

    26 #include <string.h>

    27 #include <ctype.h>

    28 

    29 #include "SDL_image.h"

    30 

    31 #define ARRAYSIZE(a) (sizeof(a) / sizeof((a)[0]))

    32 

    33 /* Table of image detection and loading functions */

    34 static struct {

    35 	char *type;

    36 	int (SDLCALL *is)(SDL_RWops *src);

    37 	SDL_Surface *(SDLCALL *load)(SDL_RWops *src);

    38 } supported[] = {

    39 	/* keep magicless formats first */

    40 	{ "PNG", IMG_isPNG, IMG_LoadPNG_RW }

    41 };

    42 

    43 

    44 extern int IMG_InitPNG();

    45 extern void IMG_QuitPNG();

    46 

    47 static int initialized = 0;

    48 

    49 int IMG_Init(int flags)

    50 {

    51 	int result = 0;

    52 

    53 	if (flags & IMG_INIT_PNG) {

    54 		if ((initialized & IMG_INIT_PNG) || IMG_InitPNG() == 0) {

    55 			result |= IMG_INIT_PNG;

    56 		}

    57 	}

    58 	initialized |= result;

    59 

    60 	return (result);

    61 }

    62 

    63 void IMG_Quit()

    64 {

    65 	if (initialized & IMG_INIT_PNG) {

    66 		IMG_QuitPNG();

    67 	}

    68 	initialized = 0;

    69 }

    70 

    71 /* Load an image from a file */

    72 SDL_Surface *IMG_Load(const char *file)

    73 {

    74     SDL_RWops *src = SDL_RWFromFile(file, "rb");

    75     char *ext = strrchr(file, '.');

    76     if(ext) {

    77         ext++;

    78     }

    79     if(!src) {

    80         /* The error message has been set in SDL_RWFromFile */

    81         return NULL;

    82     }

    83     return IMG_LoadTyped_RW(src, 1, ext);

    84 }

    85 

    86 /* Load an image from an SDL datasource (for compatibility) */

    87 SDL_Surface *IMG_Load_RW(SDL_RWops *src, int freesrc)

    88 {

    89     return IMG_LoadTyped_RW(src, freesrc, NULL);

    90 }

    91 

    92 /* Portable case-insensitive string compare function */

    93 static int IMG_string_equals(const char *str1, const char *str2)

    94 {

    95 	while ( *str1 && *str2 ) {

    96 		if ( toupper((unsigned char)*str1) !=

    97 		     toupper((unsigned char)*str2) )

    98 			break;

    99 		++str1;

   100 		++str2;

   101 	}

   102 	return (!*str1 && !*str2);

   103 }

   104 

   105 /* Load an image from an SDL datasource, optionally specifying the type */

   106 SDL_Surface *IMG_LoadTyped_RW(SDL_RWops *src, int freesrc, char *type)

   107 {

   108 	int i;

   109 	SDL_Surface *image;

   110 

   111 	/* Make sure there is something to do.. */

   112 	if ( src == NULL ) {

   113 		IMG_SetError("Passed a NULL data source");

   114 		return(NULL);

   115 	}

   116 

   117 	/* See whether or not this data source can handle seeking */

   118 	if ( SDL_RWseek(src, 0, RW_SEEK_CUR) < 0 ) {

   119 		IMG_SetError("Can't seek in this data source");

   120 		if(freesrc)

   121 			SDL_RWclose(src);

   122 		return(NULL);

   123 	}

   124 

   125 	/* Detect the type of image being loaded */

   126 	image = NULL;

   127 	for ( i=0; i < ARRAYSIZE(supported); ++i ) {

   128 		if(supported[i].is) {

   129 			if(!supported[i].is(src))

   130 				continue;

   131 		} else {

   132 			/* magicless format */

   133 			if(!type

   134 			   || !IMG_string_equals(type, supported[i].type))

   135 				continue;

   136 		}

   137 #ifdef DEBUG_IMGLIB

   138 		fprintf(stderr, "IMGLIB: Loading image as %s\n", supported[i].type);

   139 #endif

   140 		image = supported[i].load(src);

   141 		if(freesrc)

   142 			SDL_RWclose(src);

   143 		return image;

   144 	}

   145 

   146 	if ( freesrc ) {

   147 		SDL_RWclose(src);

   148 	}

   149 	IMG_SetError("Unsupported image format");

   150 	return NULL;

   151 }

   152