IMG_jpg.c
author Sam Lantinga <slouken@libsdl.org>
Fri, 12 May 2006 05:08:03 +0000
changeset 143 e01fee7bdf3b
parent 123 1f7908a9cabb
child 146 aaa5876f41ab
permissions -rw-r--r--
Added support for dynamically loading libjpeg, libpng, and libtiff.
slouken@0
     1
/*
slouken@53
     2
    SDL_image:  An example image loading library for use with SDL
slouken@121
     3
    Copyright (C) 1997-2006 Sam Lantinga
slouken@0
     4
slouken@0
     5
    This library is free software; you can redistribute it and/or
slouken@121
     6
    modify it under the terms of the GNU Lesser General Public
slouken@0
     7
    License as published by the Free Software Foundation; either
slouken@121
     8
    version 2.1 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@121
    13
    Lesser General Public License for more details.
slouken@0
    14
slouken@121
    15
    You should have received a copy of the GNU Lesser General Public
slouken@121
    16
    License along with this library; if not, write to the Free Software
slouken@121
    17
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
slouken@0
    18
slouken@0
    19
    Sam Lantinga
slouken@53
    20
    slouken@libsdl.org
slouken@0
    21
*/
slouken@0
    22
slouken@0
    23
/* This is a JPEG image file loading framework */
slouken@0
    24
slouken@0
    25
#include <stdio.h>
slouken@7
    26
#include <string.h>
slouken@61
    27
#include <setjmp.h>
slouken@0
    28
slouken@0
    29
#include "SDL_image.h"
slouken@0
    30
slouken@0
    31
#ifdef LOAD_JPG
slouken@0
    32
slouken@0
    33
#include <jpeglib.h>
slouken@0
    34
slouken@0
    35
/* Define this for fast loading and not as good image quality */
slouken@0
    36
/*#define FAST_JPEG*/
slouken@0
    37
slouken@123
    38
/* Define this for quicker (but less perfect) JPEG identification */
slouken@123
    39
#define FAST_IS_JPEG
slouken@123
    40
slouken@143
    41
static struct {
slouken@143
    42
	int loaded;
slouken@143
    43
	void *handle;
slouken@143
    44
	void (*jpeg_calc_output_dimensions) (j_decompress_ptr cinfo);
slouken@143
    45
	void (*jpeg_CreateDecompress) (j_decompress_ptr cinfo, int version, size_t structsize);
slouken@143
    46
	void (*jpeg_destroy_decompress) (j_decompress_ptr cinfo);
slouken@143
    47
	boolean (*jpeg_finish_decompress) (j_decompress_ptr cinfo);
slouken@143
    48
	int (*jpeg_read_header) (j_decompress_ptr cinfo, boolean require_image);
slouken@143
    49
	JDIMENSION (*jpeg_read_scanlines) (j_decompress_ptr cinfo, JSAMPARRAY scanlines, JDIMENSION max_lines);
slouken@143
    50
	boolean (*jpeg_resync_to_restart) (j_decompress_ptr cinfo, int desired);
slouken@143
    51
	boolean (*jpeg_start_decompress) (j_decompress_ptr cinfo);
slouken@143
    52
	struct jpeg_error_mgr * (*jpeg_std_error) (struct jpeg_error_mgr * err);
slouken@143
    53
} lib;
slouken@143
    54
slouken@143
    55
#ifdef LOAD_JPG_DYNAMIC
slouken@143
    56
int IMG_InitJPG()
slouken@143
    57
{
slouken@143
    58
	if ( lib.loaded == 0 ) {
slouken@143
    59
		lib.handle = SDL_LoadObject(LOAD_JPG_DYNAMIC);
slouken@143
    60
		if ( lib.handle == NULL ) {
slouken@143
    61
			return -1;
slouken@143
    62
		}
slouken@143
    63
		lib.jpeg_calc_output_dimensions =
slouken@143
    64
			(void (*) (j_decompress_ptr))
slouken@143
    65
			SDL_LoadFunction(lib.handle, "jpeg_calc_output_dimensions");
slouken@143
    66
		if ( lib.jpeg_calc_output_dimensions == NULL ) {
slouken@143
    67
			SDL_UnloadObject(lib.handle);
slouken@143
    68
			return -1;
slouken@143
    69
		}
slouken@143
    70
		lib.jpeg_CreateDecompress = 
slouken@143
    71
			(void (*) (j_decompress_ptr, int, size_t))
slouken@143
    72
			SDL_LoadFunction(lib.handle, "jpeg_CreateDecompress");
slouken@143
    73
		if ( lib.jpeg_CreateDecompress == NULL ) {
slouken@143
    74
			SDL_UnloadObject(lib.handle);
slouken@143
    75
			return -1;
slouken@143
    76
		}
slouken@143
    77
		lib.jpeg_destroy_decompress = 
slouken@143
    78
			(void (*) (j_decompress_ptr))
slouken@143
    79
			SDL_LoadFunction(lib.handle, "jpeg_destroy_decompress");
slouken@143
    80
		if ( lib.jpeg_destroy_decompress == NULL ) {
slouken@143
    81
			SDL_UnloadObject(lib.handle);
slouken@143
    82
			return -1;
slouken@143
    83
		}
slouken@143
    84
		lib.jpeg_finish_decompress = 
slouken@143
    85
			(boolean (*) (j_decompress_ptr))
slouken@143
    86
			SDL_LoadFunction(lib.handle, "jpeg_finish_decompress");
slouken@143
    87
		if ( lib.jpeg_finish_decompress == NULL ) {
slouken@143
    88
			SDL_UnloadObject(lib.handle);
slouken@143
    89
			return -1;
slouken@143
    90
		}
slouken@143
    91
		lib.jpeg_read_header = 
slouken@143
    92
			(int (*) (j_decompress_ptr, boolean))
slouken@143
    93
			SDL_LoadFunction(lib.handle, "jpeg_read_header");
slouken@143
    94
		if ( lib.jpeg_read_header == NULL ) {
slouken@143
    95
			SDL_UnloadObject(lib.handle);
slouken@143
    96
			return -1;
slouken@143
    97
		}
slouken@143
    98
		lib.jpeg_read_scanlines = 
slouken@143
    99
			(JDIMENSION (*) (j_decompress_ptr, JSAMPARRAY, JDIMENSION))
slouken@143
   100
			SDL_LoadFunction(lib.handle, "jpeg_read_scanlines");
slouken@143
   101
		if ( lib.jpeg_read_scanlines == NULL ) {
slouken@143
   102
			SDL_UnloadObject(lib.handle);
slouken@143
   103
			return -1;
slouken@143
   104
		}
slouken@143
   105
		lib.jpeg_resync_to_restart = 
slouken@143
   106
			(boolean (*) (j_decompress_ptr, int))
slouken@143
   107
			SDL_LoadFunction(lib.handle, "jpeg_resync_to_restart");
slouken@143
   108
		if ( lib.jpeg_resync_to_restart == NULL ) {
slouken@143
   109
			SDL_UnloadObject(lib.handle);
slouken@143
   110
			return -1;
slouken@143
   111
		}
slouken@143
   112
		lib.jpeg_start_decompress = 
slouken@143
   113
			(boolean (*) (j_decompress_ptr))
slouken@143
   114
			SDL_LoadFunction(lib.handle, "jpeg_start_decompress");
slouken@143
   115
		if ( lib.jpeg_start_decompress == NULL ) {
slouken@143
   116
			SDL_UnloadObject(lib.handle);
slouken@143
   117
			return -1;
slouken@143
   118
		}
slouken@143
   119
		lib.jpeg_std_error = 
slouken@143
   120
			(struct jpeg_error_mgr * (*) (struct jpeg_error_mgr *))
slouken@143
   121
			SDL_LoadFunction(lib.handle, "jpeg_std_error");
slouken@143
   122
		if ( lib.jpeg_std_error == NULL ) {
slouken@143
   123
			SDL_UnloadObject(lib.handle);
slouken@143
   124
			return -1;
slouken@143
   125
		}
slouken@143
   126
	}
slouken@143
   127
	++lib.loaded;
slouken@143
   128
slouken@143
   129
	return 0;
slouken@143
   130
}
slouken@143
   131
void IMG_QuitJPG()
slouken@143
   132
{
slouken@143
   133
	if ( lib.loaded == 0 ) {
slouken@143
   134
		return;
slouken@143
   135
	}
slouken@143
   136
	if ( lib.loaded == 1 ) {
slouken@143
   137
		SDL_UnloadObject(lib.handle);
slouken@143
   138
	}
slouken@143
   139
	--lib.loaded;
slouken@143
   140
}
slouken@143
   141
#else
slouken@143
   142
int IMG_InitJPG()
slouken@143
   143
{
slouken@143
   144
	if ( lib.loaded == 0 ) {
slouken@143
   145
		lib.jpeg_calc_output_dimensions = jpeg_calc_output_dimensions;
slouken@143
   146
		lib.jpeg_CreateDecompress = jpeg_CreateDecompress;
slouken@143
   147
		lib.jpeg_destroy_decompress = jpeg_destroy_decompress;
slouken@143
   148
		lib.jpeg_finish_decompress = jpeg_finish_decompress;
slouken@143
   149
		lib.jpeg_read_header = jpeg_read_header;
slouken@143
   150
		lib.jpeg_read_scanlines = jpeg_read_scanlines;
slouken@143
   151
		lib.jpeg_resync_to_restart = jpeg_resync_to_restart;
slouken@143
   152
		lib.jpeg_start_decompress = jpeg_start_decompress;
slouken@143
   153
		lib.jpeg_std_error = jpeg_std_error;
slouken@143
   154
	}
slouken@143
   155
	++lib.loaded;
slouken@143
   156
}
slouken@143
   157
void IMG_QuitJPG()
slouken@143
   158
{
slouken@143
   159
	if ( lib.loaded == 0 ) {
slouken@143
   160
		return;
slouken@143
   161
	}
slouken@143
   162
	if ( lib.loaded == 1 ) {
slouken@143
   163
	}
slouken@143
   164
	--lib.loaded;
slouken@143
   165
}
slouken@143
   166
#endif /* LOAD_JPG_DYNAMIC */
slouken@143
   167
slouken@0
   168
/* See if an image is contained in a data source */
slouken@0
   169
int IMG_isJPG(SDL_RWops *src)
slouken@0
   170
{
slouken@117
   171
	int start;
slouken@0
   172
	int is_JPG;
slouken@123
   173
	int in_scan;
slouken@0
   174
	Uint8 magic[4];
slouken@0
   175
slouken@123
   176
	/* This detection code is by Steaphan Greene <stea@cs.binghamton.edu> */
slouken@123
   177
	/* Blame me, not Sam, if this doesn't work right. */
slouken@123
   178
	/* And don't forget to report the problem to the the sdl list too! */
slouken@123
   179
slouken@117
   180
	start = SDL_RWtell(src);
slouken@0
   181
	is_JPG = 0;
slouken@123
   182
	in_scan = 0;
slouken@0
   183
	if ( SDL_RWread(src, magic, 2, 1) ) {
slouken@0
   184
		if ( (magic[0] == 0xFF) && (magic[1] == 0xD8) ) {
slouken@123
   185
			is_JPG = 1;
slouken@123
   186
			while (is_JPG == 1) {
slouken@123
   187
				if(SDL_RWread(src, magic, 1, 2) != 2) {
slouken@123
   188
					is_JPG = 0;
slouken@123
   189
				} else if( (magic[0] != 0xFF) && (in_scan == 0) ) {
slouken@123
   190
					is_JPG = 0;
slouken@123
   191
				} else if( (magic[0] != 0xFF) || (magic[1] == 0xFF) ) {
slouken@123
   192
					/* Extra padding in JPEG (legal) */
slouken@123
   193
					/* or this is data and we are scanning */
slouken@123
   194
					SDL_RWseek(src, -1, SEEK_CUR);
slouken@123
   195
				} else if(magic[1] == 0xD9) {
slouken@123
   196
					/* Got to end of good JPEG */
slouken@123
   197
					break;
slouken@123
   198
				} else if( (in_scan == 1) && (magic[1] == 0x00) ) {
slouken@123
   199
					/* This is an encoded 0xFF within the data */
slouken@123
   200
				} else if( (magic[1] >= 0xD0) && (magic[1] < 0xD9) ) {
slouken@123
   201
					/* These have nothing else */
slouken@123
   202
				} else if(SDL_RWread(src, magic+2, 1, 2) != 2) {
slouken@123
   203
					is_JPG = 0;
slouken@123
   204
				} else {
slouken@123
   205
					/* Yes, it's big-endian */
slouken@123
   206
					Uint32 start;
slouken@123
   207
					Uint32 size;
slouken@123
   208
					Uint32 end;
slouken@123
   209
					start = SDL_RWtell(src);
slouken@123
   210
					size = (magic[2] << 8) + magic[3];
slouken@123
   211
					end = SDL_RWseek(src, size-2, SEEK_CUR);
slouken@123
   212
					if ( end != start + size - 2 ) is_JPG = 0;
slouken@123
   213
					if ( magic[1] == 0xDA ) {
slouken@123
   214
						/* Now comes the actual JPEG meat */
slouken@123
   215
#ifdef	FAST_IS_JPEG
slouken@123
   216
						/* Ok, I'm convinced.  It is a JPEG. */
slouken@123
   217
						break;
slouken@123
   218
#else
slouken@123
   219
						/* I'm not convinced.  Prove it! */
slouken@123
   220
						in_scan = 1;
slouken@123
   221
#endif
slouken@123
   222
					}
slouken@123
   223
				}
slouken@0
   224
			}
slouken@0
   225
		}
slouken@0
   226
	}
slouken@117
   227
	SDL_RWseek(src, start, SEEK_SET);
slouken@0
   228
	return(is_JPG);
slouken@0
   229
}
slouken@0
   230
slouken@0
   231
#define INPUT_BUFFER_SIZE	4096
slouken@0
   232
typedef struct {
slouken@0
   233
	struct jpeg_source_mgr pub;
slouken@0
   234
slouken@0
   235
	SDL_RWops *ctx;
slouken@0
   236
	Uint8 buffer[INPUT_BUFFER_SIZE];
slouken@0
   237
} my_source_mgr;
slouken@0
   238
slouken@0
   239
/*
slouken@0
   240
 * Initialize source --- called by jpeg_read_header
slouken@0
   241
 * before any data is actually read.
slouken@0
   242
 */
slouken@27
   243
static void init_source (j_decompress_ptr cinfo)
slouken@0
   244
{
slouken@0
   245
	/* We don't actually need to do anything */
slouken@0
   246
	return;
slouken@0
   247
}
slouken@0
   248
slouken@0
   249
/*
slouken@0
   250
 * Fill the input buffer --- called whenever buffer is emptied.
slouken@0
   251
 */
slouken@27
   252
static int fill_input_buffer (j_decompress_ptr cinfo)
slouken@0
   253
{
slouken@0
   254
	my_source_mgr * src = (my_source_mgr *) cinfo->src;
slouken@0
   255
	int nbytes;
slouken@0
   256
slouken@0
   257
	nbytes = SDL_RWread(src->ctx, src->buffer, 1, INPUT_BUFFER_SIZE);
slouken@0
   258
	if (nbytes <= 0) {
slouken@0
   259
		/* Insert a fake EOI marker */
slouken@0
   260
		src->buffer[0] = (Uint8) 0xFF;
slouken@0
   261
		src->buffer[1] = (Uint8) JPEG_EOI;
slouken@0
   262
		nbytes = 2;
slouken@0
   263
	}
slouken@0
   264
	src->pub.next_input_byte = src->buffer;
slouken@0
   265
	src->pub.bytes_in_buffer = nbytes;
slouken@0
   266
slouken@0
   267
	return TRUE;
slouken@0
   268
}
slouken@0
   269
slouken@0
   270
slouken@0
   271
/*
slouken@0
   272
 * Skip data --- used to skip over a potentially large amount of
slouken@0
   273
 * uninteresting data (such as an APPn marker).
slouken@0
   274
 *
slouken@0
   275
 * Writers of suspendable-input applications must note that skip_input_data
slouken@0
   276
 * is not granted the right to give a suspension return.  If the skip extends
slouken@0
   277
 * beyond the data currently in the buffer, the buffer can be marked empty so
slouken@0
   278
 * that the next read will cause a fill_input_buffer call that can suspend.
slouken@0
   279
 * Arranging for additional bytes to be discarded before reloading the input
slouken@0
   280
 * buffer is the application writer's problem.
slouken@0
   281
 */
slouken@27
   282
static void skip_input_data (j_decompress_ptr cinfo, long num_bytes)
slouken@0
   283
{
slouken@0
   284
	my_source_mgr * src = (my_source_mgr *) cinfo->src;
slouken@0
   285
slouken@0
   286
	/* Just a dumb implementation for now.	Could use fseek() except
slouken@0
   287
	 * it doesn't work on pipes.  Not clear that being smart is worth
slouken@0
   288
	 * any trouble anyway --- large skips are infrequent.
slouken@0
   289
	 */
slouken@0
   290
	if (num_bytes > 0) {
slouken@0
   291
		while (num_bytes > (long) src->pub.bytes_in_buffer) {
slouken@0
   292
			num_bytes -= (long) src->pub.bytes_in_buffer;
slouken@0
   293
			(void) src->pub.fill_input_buffer(cinfo);
slouken@0
   294
			/* note we assume that fill_input_buffer will never
slouken@0
   295
			 * return FALSE, so suspension need not be handled.
slouken@0
   296
			 */
slouken@0
   297
		}
slouken@0
   298
		src->pub.next_input_byte += (size_t) num_bytes;
slouken@0
   299
		src->pub.bytes_in_buffer -= (size_t) num_bytes;
slouken@0
   300
	}
slouken@0
   301
}
slouken@0
   302
slouken@0
   303
/*
slouken@0
   304
 * Terminate source --- called by jpeg_finish_decompress
slouken@0
   305
 * after all data has been read.
slouken@0
   306
 */
slouken@27
   307
static void term_source (j_decompress_ptr cinfo)
slouken@0
   308
{
slouken@0
   309
	/* We don't actually need to do anything */
slouken@0
   310
	return;
slouken@0
   311
}
slouken@0
   312
slouken@0
   313
/*
slouken@0
   314
 * Prepare for input from a stdio stream.
slouken@0
   315
 * The caller must have already opened the stream, and is responsible
slouken@0
   316
 * for closing it after finishing decompression.
slouken@0
   317
 */
slouken@27
   318
static void jpeg_SDL_RW_src (j_decompress_ptr cinfo, SDL_RWops *ctx)
slouken@0
   319
{
slouken@0
   320
  my_source_mgr *src;
slouken@0
   321
slouken@0
   322
  /* The source object and input buffer are made permanent so that a series
slouken@0
   323
   * of JPEG images can be read from the same file by calling jpeg_stdio_src
slouken@0
   324
   * only before the first one.  (If we discarded the buffer at the end of
slouken@0
   325
   * one image, we'd likely lose the start of the next one.)
slouken@0
   326
   * This makes it unsafe to use this manager and a different source
slouken@0
   327
   * manager serially with the same JPEG object.  Caveat programmer.
slouken@0
   328
   */
slouken@0
   329
  if (cinfo->src == NULL) {	/* first time for this JPEG object? */
slouken@0
   330
    cinfo->src = (struct jpeg_source_mgr *)
slouken@0
   331
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
slouken@0
   332
				  sizeof(my_source_mgr));
slouken@0
   333
    src = (my_source_mgr *) cinfo->src;
slouken@0
   334
  }
slouken@0
   335
slouken@0
   336
  src = (my_source_mgr *) cinfo->src;
slouken@27
   337
  src->pub.init_source = init_source;
slouken@27
   338
  src->pub.fill_input_buffer = fill_input_buffer;
slouken@27
   339
  src->pub.skip_input_data = skip_input_data;
slouken@143
   340
  src->pub.resync_to_restart = lib.jpeg_resync_to_restart; /* use default method */
slouken@27
   341
  src->pub.term_source = term_source;
slouken@0
   342
  src->ctx = ctx;
slouken@0
   343
  src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
slouken@0
   344
  src->pub.next_input_byte = NULL; /* until buffer loaded */
slouken@0
   345
}
slouken@0
   346
slouken@61
   347
struct my_error_mgr {
slouken@61
   348
	struct jpeg_error_mgr errmgr;
slouken@61
   349
	jmp_buf escape;
slouken@61
   350
};
slouken@61
   351
slouken@61
   352
static void my_error_exit(j_common_ptr cinfo)
slouken@61
   353
{
slouken@61
   354
	struct my_error_mgr *err = (struct my_error_mgr *)cinfo->err;
slouken@61
   355
	longjmp(err->escape, 1);
slouken@61
   356
}
slouken@61
   357
slouken@61
   358
static void output_no_message(j_common_ptr cinfo)
slouken@61
   359
{
slouken@61
   360
	/* do nothing */
slouken@61
   361
}
slouken@61
   362
slouken@0
   363
/* Load a JPEG type image from an SDL datasource */
slouken@0
   364
SDL_Surface *IMG_LoadJPG_RW(SDL_RWops *src)
slouken@0
   365
{
slouken@118
   366
	int start;
slouken@0
   367
	struct jpeg_decompress_struct cinfo;
slouken@0
   368
	JSAMPROW rowptr[1];
slouken@61
   369
	SDL_Surface *volatile surface = NULL;
slouken@61
   370
	struct my_error_mgr jerr;
slouken@0
   371
slouken@98
   372
	if ( !src ) {
slouken@98
   373
		/* The error message has been set in SDL_RWFromFile */
slouken@98
   374
		return NULL;
slouken@98
   375
	}
slouken@118
   376
	start = SDL_RWtell(src);
slouken@98
   377
slouken@143
   378
	if ( IMG_InitJPG() < 0 ) {
slouken@143
   379
		return NULL;
slouken@143
   380
	}
slouken@143
   381
slouken@0
   382
	/* Create a decompression structure and load the JPEG header */
slouken@143
   383
	cinfo.err = lib.jpeg_std_error(&jerr.errmgr);
slouken@61
   384
	jerr.errmgr.error_exit = my_error_exit;
slouken@61
   385
	jerr.errmgr.output_message = output_no_message;
slouken@61
   386
	if(setjmp(jerr.escape)) {
slouken@61
   387
		/* If we get here, libjpeg found an error */
slouken@143
   388
		lib.jpeg_destroy_decompress(&cinfo);
slouken@118
   389
		if ( surface != NULL ) {
slouken@118
   390
			SDL_FreeSurface(surface);
slouken@118
   391
		}
slouken@118
   392
		SDL_RWseek(src, start, SEEK_SET);
slouken@143
   393
		IMG_QuitJPG();
slouken@61
   394
		IMG_SetError("JPEG loading error");
slouken@61
   395
		return NULL;
slouken@61
   396
	}
slouken@61
   397
slouken@143
   398
	lib.jpeg_create_decompress(&cinfo);
slouken@0
   399
	jpeg_SDL_RW_src(&cinfo, src);
slouken@143
   400
	lib.jpeg_read_header(&cinfo, TRUE);
slouken@0
   401
slouken@123
   402
	if(cinfo.num_components == 4) {
slouken@123
   403
		/* Set 32-bit Raw output */
slouken@123
   404
		cinfo.out_color_space = JCS_CMYK;
slouken@123
   405
		cinfo.quantize_colors = FALSE;
slouken@143
   406
		lib.jpeg_calc_output_dimensions(&cinfo);
slouken@123
   407
slouken@123
   408
		/* Allocate an output surface to hold the image */
slouken@123
   409
		surface = SDL_AllocSurface(SDL_SWSURFACE,
slouken@123
   410
		        cinfo.output_width, cinfo.output_height, 32,
slouken@123
   411
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
slouken@123
   412
		                   0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000);
slouken@123
   413
#else
slouken@123
   414
		                   0x0000FF00, 0x00FF0000, 0xFF000000, 0x000000FF);
slouken@123
   415
#endif
slouken@123
   416
	} else {
slouken@123
   417
		/* Set 24-bit RGB output */
slouken@123
   418
		cinfo.out_color_space = JCS_RGB;
slouken@123
   419
		cinfo.quantize_colors = FALSE;
slouken@0
   420
#ifdef FAST_JPEG
slouken@123
   421
		cinfo.scale_num   = 1;
slouken@123
   422
		cinfo.scale_denom = 1;
slouken@123
   423
		cinfo.dct_method = JDCT_FASTEST;
slouken@123
   424
		cinfo.do_fancy_upsampling = FALSE;
slouken@0
   425
#endif
slouken@143
   426
		lib.jpeg_calc_output_dimensions(&cinfo);
slouken@0
   427
slouken@123
   428
		/* Allocate an output surface to hold the image */
slouken@123
   429
		surface = SDL_AllocSurface(SDL_SWSURFACE,
slouken@123
   430
		        cinfo.output_width, cinfo.output_height, 24,
slouken@0
   431
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
slouken@123
   432
		                   0x0000FF, 0x00FF00, 0xFF0000,
slouken@0
   433
#else
slouken@123
   434
		                   0xFF0000, 0x00FF00, 0x0000FF,
slouken@0
   435
#endif
slouken@123
   436
		                   0);
slouken@123
   437
	}
slouken@123
   438
slouken@0
   439
	if ( surface == NULL ) {
slouken@143
   440
		lib.jpeg_destroy_decompress(&cinfo);
slouken@118
   441
		SDL_RWseek(src, start, SEEK_SET);
slouken@143
   442
		IMG_QuitJPG();
slouken@0
   443
		IMG_SetError("Out of memory");
slouken@118
   444
		return NULL;
slouken@0
   445
	}
slouken@0
   446
slouken@0
   447
	/* Decompress the image */
slouken@143
   448
	lib.jpeg_start_decompress(&cinfo);
slouken@0
   449
	while ( cinfo.output_scanline < cinfo.output_height ) {
slouken@0
   450
		rowptr[0] = (JSAMPROW)(Uint8 *)surface->pixels +
slouken@0
   451
		                    cinfo.output_scanline * surface->pitch;
slouken@143
   452
		lib.jpeg_read_scanlines(&cinfo, rowptr, (JDIMENSION) 1);
slouken@0
   453
	}
slouken@143
   454
	lib.jpeg_finish_decompress(&cinfo);
slouken@143
   455
	lib.jpeg_destroy_decompress(&cinfo);
slouken@143
   456
slouken@143
   457
	IMG_QuitJPG();
slouken@0
   458
slouken@0
   459
	return(surface);
slouken@0
   460
}
slouken@0
   461
slouken@0
   462
#else
slouken@0
   463
slouken@0
   464
/* See if an image is contained in a data source */
slouken@0
   465
int IMG_isJPG(SDL_RWops *src)
slouken@0
   466
{
slouken@0
   467
	return(0);
slouken@0
   468
}
slouken@0
   469
slouken@0
   470
/* Load a JPEG type image from an SDL datasource */
slouken@0
   471
SDL_Surface *IMG_LoadJPG_RW(SDL_RWops *src)
slouken@0
   472
{
slouken@0
   473
	return(NULL);
slouken@0
   474
}
slouken@0
   475
slouken@0
   476
#endif /* LOAD_JPG */