/
IMG_gif.c
642 lines (550 loc) · 17.3 KB
1
/*
2
SDL_image: An example image loading library for use with SDL
3
Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
20
21
*/
22
23
#if !defined(__APPLE__) || defined(SDL_IMAGE_USE_COMMON_BACKEND)
24
25
26
27
28
29
30
31
32
/* This is a GIF image file loading framework */
#include "SDL_image.h"
#ifdef LOAD_GIF
/* See if an image is contained in a data source */
int IMG_isGIF(SDL_RWops *src)
{
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
Sint64 start;
int is_GIF;
char magic[6];
if ( !src )
return 0;
start = SDL_RWtell(src);
is_GIF = 0;
if ( SDL_RWread(src, magic, sizeof(magic), 1) ) {
if ( (SDL_strncmp(magic, "GIF", 3) == 0) &&
((SDL_memcmp(magic + 3, "87a", 3) == 0) ||
(SDL_memcmp(magic + 3, "89a", 3) == 0)) ) {
is_GIF = 1;
}
}
SDL_RWseek(src, start, RW_SEEK_SET);
return(is_GIF);
50
51
52
53
}
/* Code from here to end of file has been adapted from XPaint: */
/* +-------------------------------------------------------------------+ */
54
55
/* | Copyright 1990, 1991, 1993 David Koblas. | */
/* | Copyright 1996 Torsten Martinsen. | */
56
57
58
59
60
/* | Permission to use, copy, modify, and distribute this software | */
/* | and its documentation for any purpose and without fee is hereby | */
/* | granted, provided that the above copyright notice appear in all | */
/* | copies and that both that copyright notice and this permission | */
/* | notice appear in supporting documentation. This software is | */
61
/* | provided "as is" without express or implied warranty. | */
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
/* +-------------------------------------------------------------------+ */
/* Adapted for use in SDL by Sam Lantinga -- 7/20/98 */
#define USED_BY_SDL
#include <stdio.h>
#include <string.h>
#ifdef USED_BY_SDL
/* Changes to work with SDL:
Include SDL header file
Use SDL_Surface rather than xpaint Image structure
Define SDL versions of RWSetMsg(), ImageNewCmap() and ImageSetCmap()
*/
#include "SDL.h"
79
80
81
#define Image SDL_Surface
#define RWSetMsg IMG_SetError
#define ImageNewCmap(w, h, s) SDL_CreateRGBSurface(SDL_SWSURFACE,w,h,8,0,0,0,0)
82
#define ImageSetCmap(s, i, R, G, B) do { \
83
84
85
86
s->format->palette->colors[i].r = R; \
s->format->palette->colors[i].g = G; \
s->format->palette->colors[i].b = B; \
} while (0)
87
88
89
90
91
92
93
94
95
/* * * * * */
#else
/* Original XPaint sources */
#include "image.h"
#include "rwTable.h"
96
97
#define SDL_RWops FILE
#define SDL_RWclose fclose
98
99
100
101
#endif /* USED_BY_SDL */
102
#define MAXCOLORMAPSIZE 256
103
104
105
#define TRUE 1
#define FALSE 0
106
107
108
109
#define CM_RED 0
#define CM_GREEN 1
#define CM_BLUE 2
110
111
#define MAX_LWZ_BITS 12
112
113
114
115
#define INTERLACE 0x40
#define LOCALCOLORMAP 0x80
#define BitSet(byte, bit) (((byte) & (bit)) == (bit))
116
117
#define ReadOK(file,buffer,len) SDL_RWread(file, buffer, len, 1)
118
119
#define LM_to_uint(a,b) (((b)<<8)|(a))
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
typedef struct {
struct {
unsigned int Width;
unsigned int Height;
unsigned char ColorMap[3][MAXCOLORMAPSIZE];
unsigned int BitPixel;
unsigned int ColorResolution;
unsigned int Background;
unsigned int AspectRatio;
int GrayScale;
} GifScreen;
struct {
int transparent;
int delayTime;
int inputFlag;
int disposal;
} Gif89;
unsigned char buf[280];
int curbit, lastbit, done, last_byte;
int fresh;
int code_size, set_code_size;
int max_code, max_code_size;
int firstcode, oldcode;
int clear_code, end_code;
int table[2][(1 << MAX_LWZ_BITS)];
int stack[(1 << (MAX_LWZ_BITS)) * 2], *sp;
int ZeroDataBlock;
} State_t;
153
154
static int ReadColorMap(SDL_RWops * src, int number,
155
unsigned char buffer[3][MAXCOLORMAPSIZE], int *flag);
156
157
158
159
static int DoExtension(SDL_RWops * src, int label, State_t * state);
static int GetDataBlock(SDL_RWops * src, unsigned char *buf, State_t * state);
static int GetCode(SDL_RWops * src, int code_size, int flag, State_t * state);
static int LWZReadByte(SDL_RWops * src, int flag, int input_code_size, State_t * state);
160
static Image *ReadImage(SDL_RWops * src, int len, int height, int,
161
unsigned char cmap[3][MAXCOLORMAPSIZE],
162
int gray, int interlace, int ignore, State_t * state);
163
164
165
166
Image *
IMG_LoadGIF_RW(SDL_RWops *src)
{
167
Sint64 start;
168
169
170
171
172
173
174
175
176
177
unsigned char buf[16];
unsigned char c;
unsigned char localColorMap[3][MAXCOLORMAPSIZE];
int grayScale;
int useGlobalColormap;
int bitPixel;
int imageCount = 0;
char version[4];
int imageNumber = 1;
Image *image = NULL;
178
179
180
State_t state;
state.ZeroDataBlock = FALSE;
state.fresh = FALSE;
181
182
if ( src == NULL ) {
183
return NULL;
184
}
185
186
start = SDL_RWtell(src);
187
if (!ReadOK(src, buf, 6)) {
188
RWSetMsg("error reading magic number");
189
190
goto done;
}
191
if (SDL_strncmp((char *) buf, "GIF", 3) != 0) {
192
RWSetMsg("not a GIF file");
193
194
goto done;
}
195
SDL_memcpy(version, (char *) buf + 3, 3);
196
197
version[3] = '\0';
198
if ((SDL_strcmp(version, "87a") != 0) && (SDL_strcmp(version, "89a") != 0)) {
199
RWSetMsg("bad version number, not '87a' or '89a'");
200
201
goto done;
}
202
203
204
205
state.Gif89.transparent = -1;
state.Gif89.delayTime = -1;
state.Gif89.inputFlag = -1;
state.Gif89.disposal = 0;
206
207
if (!ReadOK(src, buf, 7)) {
208
RWSetMsg("failed to read screen descriptor");
209
210
goto done;
}
211
212
213
214
215
216
state.GifScreen.Width = LM_to_uint(buf[0], buf[1]);
state.GifScreen.Height = LM_to_uint(buf[2], buf[3]);
state.GifScreen.BitPixel = 2 << (buf[4] & 0x07);
state.GifScreen.ColorResolution = (((buf[4] & 0x70) >> 3) + 1);
state.GifScreen.Background = buf[5];
state.GifScreen.AspectRatio = buf[6];
217
218
if (BitSet(buf[4], LOCALCOLORMAP)) { /* Global Colormap */
219
220
if (ReadColorMap(src, state.GifScreen.BitPixel,
state.GifScreen.ColorMap, &state.GifScreen.GrayScale)) {
221
RWSetMsg("error reading global colormap");
222
goto done;
223
}
224
225
}
do {
226
227
if (!ReadOK(src, &c, 1)) {
RWSetMsg("EOF / read error on image data");
228
goto done;
229
230
231
232
233
}
if (c == ';') { /* GIF terminator */
if (imageCount < imageNumber) {
RWSetMsg("only %d image%s found in file",
imageCount, imageCount > 1 ? "s" : "");
234
goto done;
235
236
237
238
239
}
}
if (c == '!') { /* Extension */
if (!ReadOK(src, &c, 1)) {
RWSetMsg("EOF / read error on extention function code");
240
goto done;
241
}
242
DoExtension(src, c, &state);
243
244
245
246
247
248
249
250
251
continue;
}
if (c != ',') { /* Not a valid start character */
continue;
}
++imageCount;
if (!ReadOK(src, buf, 9)) {
RWSetMsg("couldn't read left/top/width/height");
252
goto done;
253
254
}
useGlobalColormap = !BitSet(buf[8], LOCALCOLORMAP);
255
256
bitPixel = 1 << ((buf[8] & 0x07) + 1);
257
258
259
260
if (!useGlobalColormap) {
if (ReadColorMap(src, bitPixel, localColorMap, &grayScale)) {
RWSetMsg("error reading local colormap");
261
goto done;
262
263
264
265
266
}
image = ReadImage(src, LM_to_uint(buf[4], buf[5]),
LM_to_uint(buf[6], buf[7]),
bitPixel, localColorMap, grayScale,
BitSet(buf[8], INTERLACE),
267
imageCount != imageNumber, &state);
268
269
270
} else {
image = ReadImage(src, LM_to_uint(buf[4], buf[5]),
LM_to_uint(buf[6], buf[7]),
271
272
273
state.GifScreen.BitPixel, state.GifScreen.ColorMap,
state.GifScreen.GrayScale, BitSet(buf[8], INTERLACE),
imageCount != imageNumber, &state);
274
}
275
276
277
} while (image == NULL);
#ifdef USED_BY_SDL
278
279
if ( state.Gif89.transparent >= 0 ) {
SDL_SetColorKey(image, SDL_TRUE, state.Gif89.transparent);
280
281
282
283
}
#endif
done:
284
if ( image == NULL ) {
285
SDL_RWseek(src, start, RW_SEEK_SET);
286
}
287
288
289
290
291
292
293
294
295
296
297
298
299
300
return image;
}
static int
ReadColorMap(SDL_RWops *src, int number,
unsigned char buffer[3][MAXCOLORMAPSIZE], int *gray)
{
int i;
unsigned char rgb[3];
int flag;
flag = TRUE;
for (i = 0; i < number; ++i) {
301
302
303
304
305
306
307
308
if (!ReadOK(src, rgb, sizeof(rgb))) {
RWSetMsg("bad colormap");
return 1;
}
buffer[CM_RED][i] = rgb[0];
buffer[CM_GREEN][i] = rgb[1];
buffer[CM_BLUE][i] = rgb[2];
flag &= (rgb[0] == rgb[1] && rgb[1] == rgb[2]);
309
310
311
312
}
#if 0
if (flag)
313
*gray = (number == 2) ? PBM_TYPE : PGM_TYPE;
314
else
315
*gray = PPM_TYPE;
316
317
318
319
320
321
322
323
#else
*gray = 0;
#endif
return FALSE;
}
static int
324
DoExtension(SDL_RWops *src, int label, State_t * state)
325
{
326
unsigned char buf[256];
327
328
329
char *str;
switch (label) {
330
331
332
333
334
335
336
337
case 0x01: /* Plain Text Extension */
str = "Plain Text Extension";
break;
case 0xff: /* Application Extension */
str = "Application Extension";
break;
case 0xfe: /* Comment Extension */
str = "Comment Extension";
338
while (GetDataBlock(src, (unsigned char *) buf, state) > 0)
339
340
341
342
;
return FALSE;
case 0xf9: /* Graphic Control Extension */
str = "Graphic Control Extension";
343
344
345
346
(void) GetDataBlock(src, (unsigned char *) buf, state);
state->Gif89.disposal = (buf[0] >> 2) & 0x7;
state->Gif89.inputFlag = (buf[0] >> 1) & 0x1;
state->Gif89.delayTime = LM_to_uint(buf[1], buf[2]);
347
if ((buf[0] & 0x1) != 0)
348
state->Gif89.transparent = buf[3];
349
350
while (GetDataBlock(src, (unsigned char *) buf, state) > 0)
351
352
;
return FALSE;
353
default:
354
355
356
str = (char *)buf;
SDL_snprintf(str, 256, "UNKNOWN (0x%02x)", label);
break;
357
358
}
359
while (GetDataBlock(src, (unsigned char *) buf, state) > 0)
360
;
361
362
363
364
365
return FALSE;
}
static int
366
GetDataBlock(SDL_RWops *src, unsigned char *buf, State_t * state)
367
368
369
370
{
unsigned char count;
if (!ReadOK(src, &count, 1)) {
371
372
/* pm_message("error in getting DataBlock size" ); */
return -1;
373
}
374
state->ZeroDataBlock = count == 0;
375
376
if ((count != 0) && (!ReadOK(src, buf, count))) {
377
378
/* pm_message("error in reading DataBlock" ); */
return -1;
379
380
381
382
383
}
return count;
}
static int
384
GetCode(SDL_RWops *src, int code_size, int flag, State_t * state)
385
386
387
388
389
{
int i, j, ret;
unsigned char count;
if (flag) {
390
391
392
state->curbit = 0;
state->lastbit = 0;
state->done = FALSE;
393
return 0;
394
}
395
396
397
if ((state->curbit + code_size) >= state->lastbit) {
if (state->done) {
if (state->curbit >= state->lastbit)
398
399
400
RWSetMsg("ran off the end of my bits");
return -1;
}
401
402
state->buf[0] = state->buf[state->last_byte - 2];
state->buf[1] = state->buf[state->last_byte - 1];
403
404
405
if ((count = GetDataBlock(src, &state->buf[2], state)) <= 0)
state->done = TRUE;
406
407
408
409
state->last_byte = 2 + count;
state->curbit = (state->curbit - state->lastbit) + 16;
state->lastbit = (2 + count) * 8;
410
411
}
ret = 0;
412
413
for (i = state->curbit, j = 0; j < code_size; ++i, ++j)
ret |= ((state->buf[i / 8] & (1 << (i % 8))) != 0) << j;
414
415
state->curbit += code_size;
416
417
418
419
420
return ret;
}
static int
421
LWZReadByte(SDL_RWops *src, int flag, int input_code_size, State_t * state)
422
423
424
425
{
int code, incode;
register int i;
426
427
428
429
/* Fixed buffer overflow found by Michael Skladnikiewicz */
if (input_code_size > MAX_LWZ_BITS)
return -1;
430
if (flag) {
431
432
433
434
435
436
state->set_code_size = input_code_size;
state->code_size = state->set_code_size + 1;
state->clear_code = 1 << state->set_code_size;
state->end_code = state->clear_code + 1;
state->max_code_size = 2 * state->clear_code;
state->max_code = state->clear_code + 2;
437
438
GetCode(src, 0, TRUE, state);
439
440
state->fresh = TRUE;
441
442
443
444
for (i = 0; i < state->clear_code; ++i) {
state->table[0][i] = 0;
state->table[1][i] = i;
445
}
446
state->table[1][0] = 0;
447
for (; i < (1 << MAX_LWZ_BITS); ++i)
448
state->table[0][i] = 0;
449
450
state->sp = state->stack;
451
452
return 0;
453
454
} else if (state->fresh) {
state->fresh = FALSE;
455
do {
456
457
458
459
460
461
462
463
464
465
466
467
state->firstcode = state->oldcode = GetCode(src, state->code_size, FALSE, state);
} while (state->firstcode == state->clear_code);
return state->firstcode;
}
if (state->sp > state->stack)
return *--state->sp;
while ((code = GetCode(src, state->code_size, FALSE, state)) >= 0) {
if (code == state->clear_code) {
for (i = 0; i < state->clear_code; ++i) {
state->table[0][i] = 0;
state->table[1][i] = i;
468
469
}
for (; i < (1 << MAX_LWZ_BITS); ++i)
470
471
472
473
474
475
476
477
state->table[0][i] = state->table[1][i] = 0;
state->code_size = state->set_code_size + 1;
state->max_code_size = 2 * state->clear_code;
state->max_code = state->clear_code + 2;
state->sp = state->stack;
state->firstcode = state->oldcode = GetCode(src, state->code_size, FALSE, state);
return state->firstcode;
} else if (code == state->end_code) {
478
479
480
int count;
unsigned char buf[260];
481
if (state->ZeroDataBlock)
482
483
return -2;
484
while ((count = GetDataBlock(src, buf, state)) > 0)
485
486
487
488
489
490
491
492
493
494
495
;
if (count != 0) {
/*
* pm_message("missing EOD in data stream (common occurence)");
*/
}
return -2;
}
incode = code;
496
497
498
if (code >= state->max_code) {
*state->sp++ = state->firstcode;
code = state->oldcode;
499
}
500
while (code >= state->clear_code) {
501
502
503
504
505
/* Guard against buffer overruns */
if (code < 0 || code >= (1 << MAX_LWZ_BITS)) {
RWSetMsg("invalid LWZ data");
return -3;
}
506
507
*state->sp++ = state->table[1][code];
if (code == state->table[0][code]) {
508
509
510
RWSetMsg("circular table entry BIG ERROR");
return -3;
}
511
code = state->table[0][code];
512
513
514
515
516
517
518
}
/* Guard against buffer overruns */
if (code < 0 || code >= (1 << MAX_LWZ_BITS)) {
RWSetMsg("invalid LWZ data");
return -4;
}
519
*state->sp++ = state->firstcode = state->table[1][code];
520
521
522
523
524
525
526
527
528
if ((code = state->max_code) < (1 << MAX_LWZ_BITS)) {
state->table[0][code] = state->oldcode;
state->table[1][code] = state->firstcode;
++state->max_code;
if ((state->max_code >= state->max_code_size) &&
(state->max_code_size < (1 << MAX_LWZ_BITS))) {
state->max_code_size *= 2;
++state->code_size;
529
530
}
}
531
state->oldcode = incode;
532
533
534
if (state->sp > state->stack)
return *--state->sp;
535
536
537
538
539
540
}
return code;
}
static Image *
ReadImage(SDL_RWops * src, int len, int height, int cmapSize,
541
unsigned char cmap[3][MAXCOLORMAPSIZE],
542
int gray, int interlace, int ignore, State_t * state)
543
544
545
546
547
548
549
{
Image *image;
unsigned char c;
int i, v;
int xpos = 0, ypos = 0, pass = 0;
/*
550
** Initialize the compression routines
551
552
*/
if (!ReadOK(src, &c, 1)) {
553
554
RWSetMsg("EOF / read error on image data");
return NULL;
555
}
556
if (LWZReadByte(src, TRUE, c, state) < 0) {
557
558
RWSetMsg("error reading image");
return NULL;
559
560
}
/*
561
** If this is an "uninteresting picture" ignore it.
562
563
*/
if (ignore) {
564
while (LWZReadByte(src, FALSE, c, state) >= 0)
565
566
;
return NULL;
567
568
569
570
}
image = ImageNewCmap(len, height, cmapSize);
for (i = 0; i < cmapSize; i++)
571
572
ImageSetCmap(image, i, cmap[CM_RED][i],
cmap[CM_GREEN][i], cmap[CM_BLUE][i]);
573
574
while ((v = LWZReadByte(src, FALSE, c, state)) >= 0) {
575
#ifdef USED_BY_SDL
576
((Uint8 *)image->pixels)[xpos + ypos * image->pitch] = v;
577
#else
578
image->data[xpos + ypos * len] = v;
579
#endif
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
++xpos;
if (xpos == len) {
xpos = 0;
if (interlace) {
switch (pass) {
case 0:
case 1:
ypos += 8;
break;
case 2:
ypos += 4;
break;
case 3:
ypos += 2;
break;
}
if (ypos >= height) {
++pass;
switch (pass) {
case 1:
ypos = 4;
break;
case 2:
ypos = 2;
break;
case 3:
ypos = 1;
break;
default:
goto fini;
}
}
} else {
++ypos;
}
}
if (ypos >= height)
break;
619
620
621
622
623
624
625
626
627
628
629
630
}
fini:
return image;
}
#else
/* See if an image is contained in a data source */
int IMG_isGIF(SDL_RWops *src)
{
631
return(0);
632
633
634
635
636
}
/* Load a GIF type image from an SDL datasource */
SDL_Surface *IMG_LoadGIF_RW(SDL_RWops *src)
{
637
return(NULL);
638
639
640
}
#endif /* LOAD_GIF */
641
642
#endif /* !defined(__APPLE__) || defined(SDL_IMAGE_USE_COMMON_BACKEND) */