| 1 | ///////////////////////////////////////////////////////////////////////////// |
| 2 | // Name: gifdecod.cpp |
| 3 | // Purpose: wxGIFDecoder, GIF reader for wxImage and wxAnimation |
| 4 | // Author: Guillermo Rodriguez Garcia <guille@iies.es> |
| 5 | // Version: 3.04 |
| 6 | // RCS-ID: $Id$ |
| 7 | // Copyright: (c) Guillermo Rodriguez Garcia |
| 8 | // Licence: wxWindows licence |
| 9 | ///////////////////////////////////////////////////////////////////////////// |
| 10 | |
| 11 | #ifdef __GNUG__ |
| 12 | #pragma implementation "gifdecod.h" |
| 13 | #endif |
| 14 | |
| 15 | // For compilers that support precompilation, includes "wx.h". |
| 16 | #include "wx/wxprec.h" |
| 17 | |
| 18 | #ifdef __BORLANDC__ |
| 19 | # pragma hdrstop |
| 20 | #endif |
| 21 | |
| 22 | #ifndef WX_PRECOMP |
| 23 | # include "wx/defs.h" |
| 24 | #endif |
| 25 | |
| 26 | #if wxUSE_STREAMS && wxUSE_GIF |
| 27 | |
| 28 | #include <stdlib.h> |
| 29 | #include <string.h> |
| 30 | #include "wx/gifdecod.h" |
| 31 | |
| 32 | |
| 33 | //--------------------------------------------------------------------------- |
| 34 | // wxGIFDecoder constructor and destructor |
| 35 | //--------------------------------------------------------------------------- |
| 36 | |
| 37 | wxGIFDecoder::wxGIFDecoder(wxInputStream *s, bool anim) |
| 38 | { |
| 39 | m_f = s; |
| 40 | m_anim = anim; |
| 41 | |
| 42 | m_background = -1; |
| 43 | m_screenw = 0; |
| 44 | m_screenh = 0; |
| 45 | |
| 46 | m_pimage = NULL; |
| 47 | m_pfirst = NULL; |
| 48 | m_plast = NULL; |
| 49 | m_image = 0; |
| 50 | m_nimages = 0; |
| 51 | } |
| 52 | |
| 53 | wxGIFDecoder::~wxGIFDecoder() |
| 54 | { |
| 55 | Destroy(); |
| 56 | } |
| 57 | |
| 58 | void wxGIFDecoder::Destroy() |
| 59 | { |
| 60 | GIFImage *pimg, *paux; |
| 61 | |
| 62 | pimg = m_pfirst; |
| 63 | |
| 64 | while (pimg != NULL) |
| 65 | { |
| 66 | paux = pimg->next; |
| 67 | free(pimg->p); |
| 68 | free(pimg->pal); |
| 69 | delete pimg; |
| 70 | pimg = paux; |
| 71 | } |
| 72 | |
| 73 | m_pimage = NULL; |
| 74 | m_pfirst = NULL; |
| 75 | m_plast = NULL; |
| 76 | m_image = 0; |
| 77 | m_nimages = 0; |
| 78 | } |
| 79 | |
| 80 | |
| 81 | //--------------------------------------------------------------------------- |
| 82 | // Convert this image to a wxImage object |
| 83 | //--------------------------------------------------------------------------- |
| 84 | |
| 85 | // This function was designed by Vaclav Slavik |
| 86 | |
| 87 | bool wxGIFDecoder::ConvertToImage(wxImage *image) const |
| 88 | { |
| 89 | unsigned char *src, *dst, *pal; |
| 90 | unsigned long i; |
| 91 | int transparent; |
| 92 | |
| 93 | /* just in case... */ |
| 94 | image->Destroy(); |
| 95 | |
| 96 | /* create the image */ |
| 97 | image->Create(GetWidth(), GetHeight()); |
| 98 | |
| 99 | if (!image->Ok()) |
| 100 | return FALSE; |
| 101 | |
| 102 | pal = GetPalette(); |
| 103 | src = GetData(); |
| 104 | dst = image->GetData(); |
| 105 | transparent = GetTransparentColour(); |
| 106 | |
| 107 | /* set transparent colour mask */ |
| 108 | if (transparent != -1) |
| 109 | { |
| 110 | for (i = 0; i < 256; i++) |
| 111 | { |
| 112 | if ((pal[3 * i + 0] == 255) && |
| 113 | (pal[3 * i + 1] == 0) && |
| 114 | (pal[3 * i + 2] == 255)) |
| 115 | { |
| 116 | pal[3 * i + 2] = 254; |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | pal[3 * transparent + 0] = 255, |
| 121 | pal[3 * transparent + 1] = 0, |
| 122 | pal[3 * transparent + 2] = 255; |
| 123 | |
| 124 | image->SetMaskColour(255, 0, 255); |
| 125 | } |
| 126 | else |
| 127 | image->SetMask(FALSE); |
| 128 | |
| 129 | if (pal) |
| 130 | { |
| 131 | unsigned char* r = new unsigned char[256]; |
| 132 | unsigned char* g = new unsigned char[256]; |
| 133 | unsigned char* b = new unsigned char[256]; |
| 134 | for (i = 0; i < 256; i++) |
| 135 | { |
| 136 | r[i] = pal[3*i + 0]; |
| 137 | g[i] = pal[3*i + 1]; |
| 138 | b[i] = pal[3*i + 2]; |
| 139 | } |
| 140 | image->SetPalette(wxPalette(256, r, g, b)); |
| 141 | delete[] r; delete[] g; delete[] b; |
| 142 | } |
| 143 | |
| 144 | /* copy image data */ |
| 145 | for (i = 0; i < (GetWidth() * GetHeight()); i++, src++) |
| 146 | { |
| 147 | *(dst++) = pal[3 * (*src) + 0]; |
| 148 | *(dst++) = pal[3 * (*src) + 1]; |
| 149 | *(dst++) = pal[3 * (*src) + 2]; |
| 150 | } |
| 151 | |
| 152 | return TRUE; |
| 153 | } |
| 154 | |
| 155 | |
| 156 | //--------------------------------------------------------------------------- |
| 157 | // Data accessors |
| 158 | //--------------------------------------------------------------------------- |
| 159 | |
| 160 | // Get data for current frame |
| 161 | |
| 162 | int wxGIFDecoder::GetFrameIndex() const { return m_image; } |
| 163 | unsigned char* wxGIFDecoder::GetData() const { return (m_pimage->p); } |
| 164 | unsigned char* wxGIFDecoder::GetPalette() const { return (m_pimage->pal); } |
| 165 | unsigned int wxGIFDecoder::GetWidth() const { return (m_pimage->w); } |
| 166 | unsigned int wxGIFDecoder::GetHeight() const { return (m_pimage->h); } |
| 167 | unsigned int wxGIFDecoder::GetTop() const { return (m_pimage->top); } |
| 168 | unsigned int wxGIFDecoder::GetLeft() const { return (m_pimage->left); } |
| 169 | int wxGIFDecoder::GetTransparentColour() const { return (m_pimage->transparent); } |
| 170 | int wxGIFDecoder::GetDisposalMethod() const { return (m_pimage->disposal); } |
| 171 | long wxGIFDecoder::GetDelay() const { return (m_pimage->delay); } |
| 172 | |
| 173 | // Get global data |
| 174 | |
| 175 | unsigned int wxGIFDecoder::GetLogicalScreenWidth() const { return m_screenw; } |
| 176 | unsigned int wxGIFDecoder::GetLogicalScreenHeight() const { return m_screenh; } |
| 177 | int wxGIFDecoder::GetBackgroundColour() const { return m_background; } |
| 178 | int wxGIFDecoder::GetNumberOfFrames() const { return m_nimages; } |
| 179 | bool wxGIFDecoder::IsAnimation() const { return (m_nimages > 1); } |
| 180 | |
| 181 | |
| 182 | //--------------------------------------------------------------------------- |
| 183 | // Functions to move through the animation |
| 184 | //--------------------------------------------------------------------------- |
| 185 | |
| 186 | bool wxGIFDecoder::GoFirstFrame() |
| 187 | { |
| 188 | if (!IsAnimation()) |
| 189 | return FALSE; |
| 190 | |
| 191 | m_image = 1; |
| 192 | m_pimage = m_pfirst; |
| 193 | return TRUE; |
| 194 | } |
| 195 | |
| 196 | bool wxGIFDecoder::GoLastFrame() |
| 197 | { |
| 198 | if (!IsAnimation()) |
| 199 | return FALSE; |
| 200 | |
| 201 | m_image = m_nimages; |
| 202 | m_pimage = m_plast; |
| 203 | return TRUE; |
| 204 | } |
| 205 | |
| 206 | bool wxGIFDecoder::GoNextFrame(bool cyclic) |
| 207 | { |
| 208 | if (!IsAnimation()) |
| 209 | return FALSE; |
| 210 | |
| 211 | if ((m_image < m_nimages) || (cyclic)) |
| 212 | { |
| 213 | m_pimage = m_pimage->next; |
| 214 | m_image++; |
| 215 | |
| 216 | if (!m_pimage) |
| 217 | { |
| 218 | m_image = 1; |
| 219 | m_pimage = m_pfirst; |
| 220 | } |
| 221 | |
| 222 | return TRUE; |
| 223 | } |
| 224 | else |
| 225 | return FALSE; |
| 226 | } |
| 227 | |
| 228 | bool wxGIFDecoder::GoPrevFrame(bool cyclic) |
| 229 | { |
| 230 | if (!IsAnimation()) |
| 231 | return FALSE; |
| 232 | |
| 233 | if ((m_image > 1) || (cyclic)) |
| 234 | { |
| 235 | m_pimage = m_pimage->prev; |
| 236 | m_image--; |
| 237 | |
| 238 | if (!m_pimage) |
| 239 | { |
| 240 | m_image = m_nimages; |
| 241 | m_pimage = m_plast; |
| 242 | } |
| 243 | |
| 244 | return TRUE; |
| 245 | } |
| 246 | else |
| 247 | return FALSE; |
| 248 | } |
| 249 | |
| 250 | bool wxGIFDecoder::GoFrame(int which) |
| 251 | { |
| 252 | int i; |
| 253 | |
| 254 | if (!IsAnimation()) |
| 255 | return FALSE; |
| 256 | |
| 257 | if ((which >= 1) && (which <= m_nimages)) |
| 258 | { |
| 259 | m_pimage = m_pfirst; |
| 260 | |
| 261 | for (i = 1; i < which; i++) |
| 262 | m_pimage = m_pimage->next; |
| 263 | |
| 264 | return TRUE; |
| 265 | } |
| 266 | else |
| 267 | return FALSE; |
| 268 | } |
| 269 | |
| 270 | |
| 271 | //--------------------------------------------------------------------------- |
| 272 | // GIF reading and decoding |
| 273 | //--------------------------------------------------------------------------- |
| 274 | |
| 275 | // getcode: |
| 276 | // Reads the next code from the file stream, with size 'bits' |
| 277 | // |
| 278 | int wxGIFDecoder::getcode(int bits, int ab_fin) |
| 279 | { |
| 280 | unsigned int mask; /* bit mask */ |
| 281 | unsigned int code; /* code (result) */ |
| 282 | |
| 283 | |
| 284 | /* get remaining bits from last byte read */ |
| 285 | mask = (1 << bits) - 1; |
| 286 | code = (m_lastbyte >> (8 - m_restbits)) & mask; |
| 287 | |
| 288 | /* keep reading new bytes while needed */ |
| 289 | while (bits > m_restbits) |
| 290 | { |
| 291 | /* if no bytes left in this block, read the next block */ |
| 292 | if (m_restbyte == 0) |
| 293 | { |
| 294 | m_restbyte = (unsigned char)m_f->GetC(); |
| 295 | |
| 296 | /* Some encoders are a bit broken: instead of issuing |
| 297 | * an end-of-image symbol (ab_fin) they come up with |
| 298 | * a zero-length subblock!! We catch this here so |
| 299 | * that the decoder sees an ab_fin code. |
| 300 | */ |
| 301 | if (m_restbyte == 0) |
| 302 | { |
| 303 | code = ab_fin; |
| 304 | break; |
| 305 | } |
| 306 | |
| 307 | /* prefetch data */ |
| 308 | m_f->Read((void *) m_buffer, m_restbyte); |
| 309 | m_bufp = m_buffer; |
| 310 | } |
| 311 | |
| 312 | /* read next byte and isolate the bits we need */ |
| 313 | m_lastbyte = (unsigned char) (*m_bufp++); |
| 314 | mask = (1 << (bits - m_restbits)) - 1; |
| 315 | code = code + ((m_lastbyte & mask) << m_restbits); |
| 316 | m_restbyte--; |
| 317 | |
| 318 | /* adjust total number of bits extracted from the buffer */ |
| 319 | m_restbits = m_restbits + 8; |
| 320 | } |
| 321 | |
| 322 | /* find number of bits remaining for next code */ |
| 323 | m_restbits = (m_restbits - bits); |
| 324 | |
| 325 | return code; |
| 326 | } |
| 327 | |
| 328 | |
| 329 | // dgif: |
| 330 | // GIF decoding function. The initial code size (aka root size) |
| 331 | // is 'bits'. Supports interlaced images (interl == 1). |
| 332 | // |
| 333 | int wxGIFDecoder::dgif(GIFImage *img, int interl, int bits) |
| 334 | { |
| 335 | int *ab_prefix = new int[4096]; /* alphabet (prefixes) */ |
| 336 | int *ab_tail = new int[4096]; /* alphabet (tails) */ |
| 337 | int *stack = new int[4096]; /* decompression stack */ |
| 338 | int ab_clr; /* clear code */ |
| 339 | int ab_fin; /* end of info code */ |
| 340 | int ab_bits; /* actual symbol width, in bits */ |
| 341 | int ab_free; /* first free position in alphabet */ |
| 342 | int ab_max; /* last possible character in alphabet */ |
| 343 | int pass; /* pass number in interlaced images */ |
| 344 | int pos; /* index into decompresion stack */ |
| 345 | unsigned int x, y; /* position in image buffer */ |
| 346 | |
| 347 | int code, readcode, lastcode, abcabca; |
| 348 | |
| 349 | /* these won't change */ |
| 350 | ab_clr = (1 << bits); |
| 351 | ab_fin = (1 << bits) + 1; |
| 352 | |
| 353 | /* these will change through the decompression proccess */ |
| 354 | ab_bits = bits + 1; |
| 355 | ab_free = (1 << bits) + 2; |
| 356 | ab_max = (1 << ab_bits) - 1; |
| 357 | lastcode = -1; |
| 358 | abcabca = -1; |
| 359 | pass = 1; |
| 360 | pos = x = y = 0; |
| 361 | |
| 362 | /* reset decoder vars */ |
| 363 | m_restbits = 0; |
| 364 | m_restbyte = 0; |
| 365 | m_lastbyte = 0; |
| 366 | |
| 367 | do |
| 368 | { |
| 369 | /* get next code */ |
| 370 | readcode = code = getcode(ab_bits, ab_fin); |
| 371 | |
| 372 | /* end of image? */ |
| 373 | if (code == ab_fin) break; |
| 374 | |
| 375 | /* reset alphabet? */ |
| 376 | if (code == ab_clr) |
| 377 | { |
| 378 | /* reset main variables */ |
| 379 | ab_bits = bits + 1; |
| 380 | ab_free = (1 << bits) + 2; |
| 381 | ab_max = (1 << ab_bits) - 1; |
| 382 | lastcode = -1; |
| 383 | abcabca = -1; |
| 384 | |
| 385 | /* skip to next code */ |
| 386 | continue; |
| 387 | } |
| 388 | |
| 389 | /* unknown code: special case (like in ABCABCA) */ |
| 390 | if (code >= ab_free) |
| 391 | { |
| 392 | code = lastcode; /* take last string */ |
| 393 | stack[pos++] = abcabca; /* add first character */ |
| 394 | } |
| 395 | |
| 396 | /* build the string for this code in the stack */ |
| 397 | while (code > ab_clr) |
| 398 | { |
| 399 | stack[pos++] = ab_tail[code]; |
| 400 | code = ab_prefix[code]; |
| 401 | } |
| 402 | stack[pos] = code; /* push last code into the stack */ |
| 403 | abcabca = code; /* save for special case */ |
| 404 | |
| 405 | /* make new entry in alphabet (only if NOT just cleared) */ |
| 406 | if (lastcode != -1) |
| 407 | { |
| 408 | ab_prefix[ab_free] = lastcode; |
| 409 | ab_tail[ab_free] = code; |
| 410 | ab_free++; |
| 411 | |
| 412 | if ((ab_free > ab_max) && (ab_bits < 12)) |
| 413 | { |
| 414 | ab_bits++; |
| 415 | ab_max = (1 << ab_bits) - 1; |
| 416 | } |
| 417 | } |
| 418 | |
| 419 | /* dump stack data to the buffer */ |
| 420 | while (pos >= 0) |
| 421 | { |
| 422 | (img->p)[x + (y * (img->w))] = (char)stack[pos--]; |
| 423 | |
| 424 | if (++x >= (img->w)) |
| 425 | { |
| 426 | x = 0; |
| 427 | |
| 428 | if (interl) |
| 429 | { |
| 430 | /* support for interlaced images */ |
| 431 | switch (pass) |
| 432 | { |
| 433 | case 1: y += 8; break; |
| 434 | case 2: y += 8; break; |
| 435 | case 3: y += 4; break; |
| 436 | case 4: y += 2; break; |
| 437 | } |
| 438 | if (y >= (img->h)) |
| 439 | { |
| 440 | switch (++pass) |
| 441 | { |
| 442 | case 2: y = 4; break; |
| 443 | case 3: y = 2; break; |
| 444 | case 4: y = 1; break; |
| 445 | } |
| 446 | } |
| 447 | } |
| 448 | else |
| 449 | { |
| 450 | /* non-interlaced */ |
| 451 | y++; |
| 452 | } |
| 453 | } |
| 454 | } |
| 455 | |
| 456 | pos = 0; |
| 457 | lastcode = readcode; |
| 458 | } |
| 459 | while (code != ab_fin); |
| 460 | |
| 461 | delete [] ab_prefix ; |
| 462 | delete [] ab_tail ; |
| 463 | delete [] stack ; |
| 464 | |
| 465 | return 0; |
| 466 | } |
| 467 | |
| 468 | |
| 469 | // CanRead: |
| 470 | // Returns TRUE if the file looks like a valid GIF, FALSE otherwise. |
| 471 | // |
| 472 | bool wxGIFDecoder::CanRead() |
| 473 | { |
| 474 | unsigned char buf[3]; |
| 475 | |
| 476 | m_f->Read(buf, 3); |
| 477 | m_f->SeekI(-3, wxFromCurrent); |
| 478 | |
| 479 | return (memcmp(buf, "GIF", 3) == 0); |
| 480 | } |
| 481 | |
| 482 | |
| 483 | // ReadGIF: |
| 484 | // Reads and decodes one or more GIF images, depending on whether |
| 485 | // animated GIF support is enabled. Can read GIFs with any bit |
| 486 | // size (color depth), but the output images are always expanded |
| 487 | // to 8 bits per pixel. Also, the image palettes always contain |
| 488 | // 256 colors, although some of them may be unused. Returns wxGIF_OK |
| 489 | // (== 0) on success, or an error code if something fails (see |
| 490 | // header file for details) |
| 491 | // |
| 492 | int wxGIFDecoder::ReadGIF() |
| 493 | { |
| 494 | int ncolors, bits, interl, transparent, disposal, i; |
| 495 | long size; |
| 496 | long delay; |
| 497 | unsigned char type = 0; |
| 498 | unsigned char pal[768]; |
| 499 | unsigned char buf[16]; |
| 500 | GIFImage **ppimg; |
| 501 | GIFImage *pimg, *pprev; |
| 502 | |
| 503 | /* check GIF signature */ |
| 504 | if (!CanRead()) |
| 505 | return wxGIF_INVFORMAT; |
| 506 | |
| 507 | /* check for animated GIF support (ver. >= 89a) */ |
| 508 | m_f->Read(buf, 6); |
| 509 | |
| 510 | if (memcmp(buf + 3, "89a", 3) < 0) |
| 511 | m_anim = FALSE; |
| 512 | |
| 513 | /* read logical screen descriptor block (LSDB) */ |
| 514 | m_f->Read(buf, 7); |
| 515 | m_screenw = buf[0] + 256 * buf[1]; |
| 516 | m_screenh = buf[2] + 256 * buf[3]; |
| 517 | |
| 518 | /* load global color map if available */ |
| 519 | if ((buf[4] & 0x80) == 0x80) |
| 520 | { |
| 521 | m_background = buf[5]; |
| 522 | |
| 523 | ncolors = 2 << (buf[4] & 0x07); |
| 524 | m_f->Read(pal, 3 * ncolors); |
| 525 | } |
| 526 | |
| 527 | /* transparent colour, disposal method and delay default to unused */ |
| 528 | transparent = -1; |
| 529 | disposal = -1; |
| 530 | delay = -1; |
| 531 | |
| 532 | /* read images */ |
| 533 | ppimg = &m_pfirst; |
| 534 | pprev = NULL; |
| 535 | pimg = NULL; |
| 536 | |
| 537 | bool done = FALSE; |
| 538 | |
| 539 | while(!done) |
| 540 | { |
| 541 | type = (unsigned char)m_f->GetC(); |
| 542 | |
| 543 | /* end of data? */ |
| 544 | if (type == 0x3B) |
| 545 | { |
| 546 | done = TRUE; |
| 547 | } |
| 548 | else |
| 549 | /* extension block? */ |
| 550 | if (type == 0x21) |
| 551 | { |
| 552 | if (((unsigned char)m_f->GetC()) == 0xF9) |
| 553 | /* graphics control extension, parse it */ |
| 554 | { |
| 555 | m_f->Read(buf, 6); |
| 556 | |
| 557 | /* read delay and convert from 1/100 of a second to ms */ |
| 558 | delay = 10 * (buf[2] + 256 * buf[3]); |
| 559 | |
| 560 | /* read transparent colour index, if used */ |
| 561 | if (buf[1] & 0x01) |
| 562 | transparent = buf[4]; |
| 563 | |
| 564 | /* read disposal method */ |
| 565 | disposal = (buf[1] & 0x1C) - 1; |
| 566 | } |
| 567 | else |
| 568 | /* other extension, skip */ |
| 569 | { |
| 570 | while ((i = (unsigned char)m_f->GetC()) != 0) |
| 571 | { |
| 572 | m_f->SeekI(i, wxFromCurrent); |
| 573 | } |
| 574 | } |
| 575 | } |
| 576 | else |
| 577 | /* image descriptor block? */ |
| 578 | if (type == 0x2C) |
| 579 | { |
| 580 | /* allocate memory for IMAGEN struct */ |
| 581 | pimg = (*ppimg) = new GIFImage(); |
| 582 | |
| 583 | if (pimg == NULL) |
| 584 | { |
| 585 | Destroy(); |
| 586 | return wxGIF_MEMERR; |
| 587 | } |
| 588 | |
| 589 | /* fill in the data */ |
| 590 | m_f->Read(buf, 9); |
| 591 | pimg->left = buf[4] + 256 * buf[5]; |
| 592 | pimg->top = buf[4] + 256 * buf[5]; |
| 593 | pimg->w = buf[4] + 256 * buf[5]; |
| 594 | pimg->h = buf[6] + 256 * buf[7]; |
| 595 | interl = ((buf[8] & 0x40)? 1 : 0); |
| 596 | size = pimg->w * pimg->h; |
| 597 | |
| 598 | pimg->transparent = transparent; |
| 599 | pimg->disposal = disposal; |
| 600 | pimg->delay = delay; |
| 601 | pimg->next = NULL; |
| 602 | pimg->prev = pprev; |
| 603 | pprev = pimg; |
| 604 | ppimg = &pimg->next; |
| 605 | |
| 606 | /* allocate memory for image and palette */ |
| 607 | pimg->p = (unsigned char *) malloc((size_t)size); |
| 608 | pimg->pal = (unsigned char *) malloc(768); |
| 609 | |
| 610 | if ((!pimg->p) || (!pimg->pal)) |
| 611 | { |
| 612 | Destroy(); |
| 613 | return wxGIF_MEMERR; |
| 614 | } |
| 615 | |
| 616 | /* load local color map if available, else use global map */ |
| 617 | if ((buf[8] & 0x80) == 0x80) |
| 618 | { |
| 619 | ncolors = 2 << (buf[8] & 0x07); |
| 620 | m_f->Read(pimg->pal, 3 * ncolors); |
| 621 | } |
| 622 | else |
| 623 | memcpy(pimg->pal, pal, 768); |
| 624 | |
| 625 | /* get initial code size from first byte in raster data */ |
| 626 | bits = (unsigned char)m_f->GetC(); |
| 627 | |
| 628 | /* decode image */ |
| 629 | dgif(pimg, interl, bits); |
| 630 | m_nimages++; |
| 631 | |
| 632 | /* if this is not an animated GIF, exit after first image */ |
| 633 | if (!m_anim) |
| 634 | done = TRUE; |
| 635 | } |
| 636 | } |
| 637 | |
| 638 | /* setup image pointers */ |
| 639 | if (m_nimages != 0) |
| 640 | { |
| 641 | m_image = 1; |
| 642 | m_plast = pimg; |
| 643 | m_pimage = m_pfirst; |
| 644 | } |
| 645 | |
| 646 | /* try to read to the end of the stream */ |
| 647 | while (type != 0x3B) |
| 648 | { |
| 649 | type = (unsigned char)m_f->GetC(); |
| 650 | |
| 651 | if (type == 0x21) |
| 652 | { |
| 653 | /* extension type */ |
| 654 | (void) m_f->GetC(); |
| 655 | |
| 656 | /* skip all data */ |
| 657 | while ((i = (unsigned char)m_f->GetC()) != 0) |
| 658 | { |
| 659 | m_f->SeekI(i, wxFromCurrent); |
| 660 | } |
| 661 | } |
| 662 | else if (type == 0x2C) |
| 663 | { |
| 664 | /* image descriptor block */ |
| 665 | m_f->Read(buf, 9); |
| 666 | |
| 667 | /* local color map */ |
| 668 | if ((buf[8] & 0x80) == 0x80) |
| 669 | { |
| 670 | ncolors = 2 << (buf[8] & 0x07); |
| 671 | m_f->SeekI(3 * ncolors, wxFromCurrent); |
| 672 | } |
| 673 | |
| 674 | /* initial code size */ |
| 675 | (void) m_f->GetC(); |
| 676 | |
| 677 | /* skip all data */ |
| 678 | while ((i = (unsigned char)m_f->GetC()) != 0) |
| 679 | { |
| 680 | m_f->SeekI(i, wxFromCurrent); |
| 681 | } |
| 682 | } |
| 683 | else if ((type != 0x3B) && (type != 00)) /* testing */ |
| 684 | { |
| 685 | /* images are OK, but couldn't read to the end of the stream */ |
| 686 | return wxGIF_TRUNCATED; |
| 687 | } |
| 688 | } |
| 689 | |
| 690 | return wxGIF_OK; |
| 691 | } |
| 692 | |
| 693 | #endif // wxUSE_STREAMS && wxUSE_GIF |