sys/src/cmd/jpg/readgif.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4 #include <draw.h>
   5 #include "imagefile.h"
   6
   7 typedef struct Entry Entry;
   8 typedef struct Header Header;
   9
  10 struct Entry{
  11         int             prefix;
  12         int             exten;
  13 };
  14
  15 struct Header{
  16         Biobuf  *fd;
  17         char            err[256];
  18         jmp_buf errlab;
  19         uchar   buf[3*256];
  20         char            vers[8];
  21         uchar   *globalcmap;
  22         int             screenw;
  23         int             screenh;
  24         int             fields;
  25         int             bgrnd;
  26         int             aspect;
  27         int             flags;
  28         int             delay;
  29         int             trindex;
  30         int             loopcount;
  31         Entry   tbl[4096];
  32         Rawimage        **array;
  33         Rawimage        *new;
  34
  35         uchar   *pic;
  36 };
  37
  38 static char             readerr[] = "ReadGIF: read error: %r";
  39 static char             extreaderr[] = "ReadGIF: can't read extension: %r";
  40 static char             memerr[] = "ReadGIF: malloc failed: %r";
  41
  42 static Rawimage**       readarray(Header*, int);
  43 static Rawimage*        readone(Header*);
  44 static void                     readheader(Header*);
  45 static void                     skipextension(Header*);
  46 static uchar*           readcmap(Header*, int);
  47 static uchar*           decode(Header*, Rawimage*, Entry*);
  48 static void             interlace(Header*, Rawimage*);
  49
  50 static
  51 void
  52 clear(void **p)
  53 {
  54         if(*p){
  55                 free(*p);
  56                 *p = nil;
  57         }
  58 }
  59
  60 static
  61 void
  62 giffreeall(Header *h, int freeimage)
  63 {
  64         int i;
  65
  66         if(h->fd){
  67                 Bterm(h->fd);
  68                 h->fd = nil;
  69         }
  70         clear(&h->pic);
  71         if(h->new){
  72                 clear(&h->new->cmap);
  73                 clear(&h->new->chans[0]);
  74                 clear(&h->new);
  75         }
  76         clear(&h->globalcmap);
  77         if(freeimage && h->array!=nil){
  78                 for(i=0; h->array[i]; i++){
  79                         clear(&h->array[i]->cmap);
  80                         clear(&h->array[i]->chans[0]);
  81                 }
  82                 clear(&h->array);
  83         }
  84 }
  85
  86 static
  87 void
  88 giferror(Header *h, char *fmt, ...)
  89 {
  90         va_list arg;
  91
  92         va_start(arg, fmt);
  93         vseprint(h->err, h->err+sizeof h->err, fmt, arg);
  94         va_end(arg);
  95
  96         werrstr("%s", h->err);
  97         giffreeall(h, 1);
  98         longjmp(h->errlab, 1);
  99 }
 100
 101
 102 Rawimage**
 103 readgif(int fd, int colorspace, int justone)
 104 {
 105         Rawimage **a;
 106         Biobuf b;
 107         Header *h;
 108         char buf[ERRMAX];
 109
 110         buf[0] = '\0';
 111         USED(colorspace);
 112         if(Binit(&b, fd, OREAD) < 0)
 113                 return nil;
 114         h = malloc(sizeof(Header));
 115         if(h == nil){
 116                 Bterm(&b);
 117                 return nil;
 118         }
 119         memset(h, 0, sizeof(Header));
 120         h->fd = &b;
 121         errstr(buf, sizeof buf);        /* throw it away */
 122         if(setjmp(h->errlab))
 123                 a = nil;
 124         else
 125                 a = readarray(h, justone);
 126         giffreeall(h, 0);
 127         free(h);
 128         return a;
 129 }
 130
 131 static
 132 void
 133 inittbl(Header *h)
 134 {
 135         int i;
 136         Entry *tbl;
 137
 138         tbl = h->tbl;
 139         for(i=0; i<258; i++) {
 140                 tbl[i].prefix = -1;
 141                 tbl[i].exten = i;
 142         }
 143 }
 144
 145 static
 146 Rawimage**
 147 readarray(Header *h, int justone)
 148 {
 149         Entry *tbl;
 150         Rawimage *new, **array;
 151         int c, nimages;
 152
 153         tbl = h->tbl;
 154
 155         readheader(h);
 156
 157         if(h->fields & 0x80)
 158                 h->globalcmap = readcmap(h, (h->fields&7)+1);
 159         array = malloc(sizeof(Rawimage*));
 160         if(array == nil)
 161                 giferror(h, memerr);
 162         nimages = 0;
 163         array[0] = nil;
 164         h->array = array;
 165
 166         for(;;){
 167                 switch(c = Bgetc(h->fd)){
 168                 case Beof:
 169                         goto Return;
 170
 171                 case 0x21:      /* Extension (ignored) */
 172                         skipextension(h);
 173                         break;
 174
 175                 case 0x2C:      /* Image Descriptor */
 176                         inittbl(h);
 177                         new = readone(h);
 178                         if(new->fields & 0x80){
 179                                 new->cmaplen = 3*(1<<((new->fields&7)+1));
 180                                 new->cmap = readcmap(h, (new->fields&7)+1);
 181                         }else{
 182                                 if(h->globalcmap == nil)
 183                                         giferror(h, "ReadGIF: globalcmap missing");
 184                                 new->cmaplen = 3*(1<<((h->fields&7)+1));
 185                                 new->cmap = malloc(new->cmaplen);
 186                                 if(new->cmap == nil)
 187                                         giferror(h, memerr);
 188                                 memmove(new->cmap, h->globalcmap, new->cmaplen);
 189                         }
 190                         h->new = new;
 191                         new->chans[0] = decode(h, new, tbl);
 192                         if(new->fields & 0x40)
 193                                 interlace(h, new);
 194                         new->gifflags = h->flags;
 195                         new->gifdelay = h->delay;
 196                         new->giftrindex = h->trindex;
 197                         new->gifloopcount = h->loopcount;
 198                         array = realloc(h->array, (nimages+2)*sizeof(Rawimage*));
 199                         if(array == nil)
 200                                 giferror(h, memerr);
 201                         array[nimages++] = new;
 202                         array[nimages] = nil;
 203                         h->array = array;
 204                         h->new = nil;
 205                         if(justone)
 206                                 goto Return;
 207                         break;
 208
 209                 case 0x3B:      /* Trailer */
 210                         goto Return;
 211
 212                 default:
 213                         fprint(2, "ReadGIF: unknown block type: 0x%.2x\n", c);
 214                         goto Return;
 215                 }
 216         }
 217
 218    Return:
 219         if(array[0]==nil || array[0]->chans[0] == nil)
 220                 giferror(h, "ReadGIF: no picture in file");
 221
 222         return array;
 223 }
 224
 225 static
 226 void
 227 readheader(Header *h)
 228 {
 229         if(Bread(h->fd, h->buf, 13) != 13)
 230                 giferror(h, "ReadGIF: can't read header: %r");
 231         memmove(h->vers, h->buf, 6);
 232         if(strcmp(h->vers, "GIF87a")!=0 &&  strcmp(h->vers, "GIF89a")!=0)
 233                 giferror(h, "ReadGIF: can't recognize format %s", h->vers);
 234         h->screenw = h->buf[6]+(h->buf[7]<<8);
 235         h->screenh = h->buf[8]+(h->buf[9]<<8);
 236         h->fields = h->buf[10];
 237         h->bgrnd = h->buf[11];
 238         h->aspect = h->buf[12];
 239         h->flags = 0;
 240         h->delay = 0;
 241         h->trindex = 0;
 242         h->loopcount = -1;
 243 }
 244
 245 static
 246 uchar*
 247 readcmap(Header *h, int size)
 248 {
 249         uchar *map;
 250
 251         if(size > 8)
 252                 giferror(h, "ReadGIF: can't handles %d bits per pixel", size);
 253         size = 3*(1<<size);
 254         if(Bread(h->fd, h->buf, size) != size)
 255                 giferror(h, "ReadGIF: short read on color map");
 256         map = malloc(size);
 257         if(map == nil)
 258                 giferror(h, memerr);
 259         memmove(map, h->buf, size);
 260         return map;
 261 }
 262
 263 static
 264 Rawimage*
 265 readone(Header *h)
 266 {
 267         Rawimage *i;
 268         int left, top, width, height;
 269
 270         if(Bread(h->fd, h->buf, 9) != 9)
 271                 giferror(h, "ReadGIF: can't read image descriptor: %r");
 272         i = malloc(sizeof(Rawimage));
 273         if(i == nil)
 274                 giferror(h, memerr);
 275         left = h->buf[0]+(h->buf[1]<<8);
 276         top = h->buf[2]+(h->buf[3]<<8);
 277         width = h->buf[4]+(h->buf[5]<<8);
 278         height = h->buf[6]+(h->buf[7]<<8);
 279         i->fields = h->buf[8];
 280         i->r.min.x = left;
 281         i->r.min.y = top;
 282         i->r.max.x = left+width;
 283         i->r.max.y = top+height;
 284         i->nchans = 1;
 285         i->chandesc = CRGB1;
 286         memset(i->chans, 0, sizeof(i->chans));
 287         return i;
 288 }
 289
 290
 291 static
 292 int
 293 readdata(Header *h, uchar *data)
 294 {
 295         int nbytes, n;
 296
 297         nbytes = Bgetc(h->fd);
 298         if(nbytes < 0)
 299                 giferror(h, "ReadGIF: can't read data: %r");
 300         if(nbytes == 0)
 301                 return 0;
 302         n = Bread(h->fd, data, nbytes);
 303         if(n < 0)
 304                 giferror(h, "ReadGIF: can't read data: %r");
 305         if(n != nbytes)
 306                 fprint(2, "ReadGIF: short data subblock\n");
 307         return n;
 308 }
 309
 310 static
 311 void
 312 graphiccontrol(Header *h)
 313 {
 314         if(Bread(h->fd, h->buf, 5+1) != 5+1)
 315                 giferror(h, readerr);
 316         h->flags = h->buf[1];
 317         h->delay = h->buf[2]+(h->buf[3]<<8);
 318         h->trindex = h->buf[4];
 319 }
 320
 321 static
 322 void
 323 skipextension(Header *h)
 324 {
 325         int type, hsize, hasdata, n;
 326         uchar data[256];
 327
 328         hsize = 0;
 329         hasdata = 0;
 330
 331         type = Bgetc(h->fd);
 332         switch(type){
 333         case Beof:
 334                 giferror(h, extreaderr);
 335                 break;
 336         case 0x01:      /* Plain Text Extension */
 337                 hsize = 13;
 338                 hasdata = 1;
 339                 break;
 340         case 0xF9:      /* Graphic Control Extension */
 341                 graphiccontrol(h);
 342                 return;
 343         case 0xFE:      /* Comment Extension */
 344                 hasdata = 1;
 345                 break;
 346         case 0xFF:      /* Application Extension */
 347                 hsize = Bgetc(h->fd);
 348                 /* standard says this must be 11, but Adobe likes to put out 10-byte ones,
 349                  * so we pay attention to the field. */
 350                 hasdata = 1;
 351                 break;
 352         default:
 353                 giferror(h, "ReadGIF: unknown extension");
 354         }
 355         if(hsize>0 && Bread(h->fd, h->buf, hsize) != hsize)
 356                 giferror(h, extreaderr);
 357         if(!hasdata){
 358                 /*
 359                  * This code used to check h->buf[hsize-1] != 0
 360                  * and giferror if so, but if !hasdata, hsize == 0.
 361                  */
 362                 return;
 363         }
 364
 365         /* loop counter: Application Extension with NETSCAPE2.0 as string and 1 <loop.count> in data */
 366         if(type == 0xFF && hsize==11 && memcmp(h->buf, "NETSCAPE2.0", 11)==0){
 367                 n = readdata(h, data);
 368                 if(n == 0)
 369                         return;
 370                 if(n==3 && data[0]==1)
 371                         h->loopcount = data[1] | (data[2]<<8);
 372         }
 373         while(readdata(h, data) != 0)
 374                 ;
 375 }
 376
 377 static
 378 uchar*
 379 decode(Header *h, Rawimage *i, Entry *tbl)
 380 {
 381         int c, incode, codesize, CTM, EOD, pici, datai, stacki, nbits, sreg, fc, code, piclen;
 382         int csize, nentry, maxentry, first, ocode, ndata, nb;
 383         uchar clip, *p, *pic;
 384         uchar stack[4096], data[256];
 385
 386         if(Bread(h->fd, h->buf, 1) != 1)
 387                 giferror(h, "ReadGIF: can't read data: %r");
 388         codesize = h->buf[0];
 389         if(codesize>8 || 0>codesize)
 390                 giferror(h, "ReadGIF: can't handle codesize %d", codesize);
 391
 392         CTM =1<<codesize;
 393         EOD = CTM+1;
 394
 395         piclen = (i->r.max.x-i->r.min.x)*(i->r.max.y-i->r.min.y);
 396         i->chanlen = piclen;
 397         pic = malloc(piclen);
 398         if(pic == nil)
 399                 giferror(h, memerr);
 400         h->pic = pic;
 401         pici = 0;
 402         ndata = 0;
 403         datai = 0;
 404         nbits = 0;
 405         sreg = 0;
 406         fc = 0;
 407
 408     Loop:
 409         for(;;){
 410                 csize = codesize+1;
 411                 nentry = EOD+1;
 412                 maxentry = (1<<csize)-1;
 413                 first = 1;
 414                 ocode = -1;
 415
 416                 for(;; ocode = incode) {
 417                         while(nbits < csize) {
 418                                 if(datai == ndata){
 419                                         ndata = readdata(h, data);
 420                                         if(ndata == 0)
 421                                                 goto Return;
 422                                         datai = 0;
 423                                 }
 424                                 c = data[datai++];
 425                                 sreg |= c<<nbits;
 426                                 nbits += 8;
 427                         }
 428                         code = sreg & ((1<<csize) - 1);
 429                         sreg >>= csize;
 430                         nbits -= csize;
 431
 432                         if(code == EOD){
 433                                 ndata = readdata(h, data);
 434                                 if(ndata != 0)
 435                                         fprint(2, "ReadGIF: unexpected data past EOD\n");
 436                                 goto Return;
 437                         }
 438
 439                         if(code == CTM)
 440                                 goto Loop;
 441
 442                         stacki = (sizeof stack)-1;
 443
 444                         incode = code;
 445
 446                         /* special case for KwKwK */
 447                         if(code == nentry) {
 448                                 stack[stacki--] = fc;
 449                                 code = ocode;
 450                         }
 451
 452                         if(code > nentry){
 453                                 fprint(2, "ReadGIF: GIF invalid, code out of range, %x > %x\n", code, nentry);
 454                                 code = nentry;
 455                         }
 456                         for(c=code; stacki>0 && c>=0; c=tbl[c].prefix)
 457                                 stack[stacki--] = tbl[c].exten;
 458
 459                         nb = (sizeof stack)-(stacki+1);
 460                         if(pici+nb > piclen){
 461                                 /* this common error is harmless
 462                                  * we have to keep reading to keep the blocks in sync */
 463                                 ;
 464                         }else{
 465                                 memmove(pic+pici, stack+stacki+1, sizeof stack - (stacki+1));
 466                                 pici += nb;
 467                         }
 468
 469                         fc = stack[stacki+1];
 470
 471                         if(first){
 472                                 first = 0;
 473                                 continue;
 474                         }
 475                         #define early 0 /* peculiar tiff feature here for reference */
 476                         if(nentry == maxentry-early) {
 477                                 if(csize >= 12)
 478                                         continue;
 479                                 csize++;
 480                                 maxentry = (1<<csize);
 481                                 if(csize < 12)
 482                                         maxentry--;
 483                         }
 484                         tbl[nentry].prefix = ocode;
 485                         tbl[nentry].exten = fc;
 486                         nentry++;
 487                 }
 488         }
 489
 490 Return:
 491         if(i->cmap!=nil && i->cmaplen!=3*256){
 492                 clip = (i->cmaplen/3)-1;
 493                 for(p = pic; p < pic+piclen; p++)
 494                         if(*p > clip)
 495                                 *p = clip;
 496         }
 497         h->pic = nil;
 498         return pic;
 499 }
 500
 501 static
 502 void
 503 interlace(Header *h, Rawimage *image)
 504 {
 505         uchar *pic;
 506         Rectangle r;
 507         int dx, yy, y;
 508         uchar *ipic;
 509
 510         pic = image->chans[0];
 511         r = image->r;
 512         dx = r.max.x-r.min.x;
 513         ipic = malloc(dx*(r.max.y-r.min.y));
 514         if(ipic == nil)
 515                 giferror(h, nil);
 516
 517         /* Group 1: every 8th row, starting with row 0 */
 518         yy = 0;
 519         for(y=r.min.y; y<r.max.y; y+=8){
 520                 memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
 521                 yy++;
 522         }
 523
 524         /* Group 2: every 8th row, starting with row 4 */
 525         for(y=r.min.y+4; y<r.max.y; y+=8){
 526                 memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
 527                 yy++;
 528         }
 529
 530         /* Group 3: every 4th row, starting with row 2 */
 531         for(y=r.min.y+2; y<r.max.y; y+=4){
 532                 memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
 533                 yy++;
 534         }
 535
 536         /* Group 4: every 2nd row, starting with row 1 */
 537         for(y=r.min.y+1; y<r.max.y; y+=2){
 538                 memmove(&ipic[(y-r.min.y)*dx], &pic[yy*dx], dx);
 539                 yy++;
 540         }
 541
 542         free(image->chans[0]);
 543         image->chans[0] = ipic;
 544 }