| 1 | ///////////////////////////////////////////////////////////////////////////// |
| 2 | // Name: src/common/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 | // For compilers that support precompilation, includes "wx.h". |
| 12 | #include "wx/wxprec.h" |
| 13 | |
| 14 | #ifdef __BORLANDC__ |
| 15 | #pragma hdrstop |
| 16 | #endif |
| 17 | |
| 18 | #if wxUSE_STREAMS && wxUSE_GIF |
| 19 | |
| 20 | #ifndef WX_PRECOMP |
| 21 | #include "wx/palette.h" |
| 22 | #endif |
| 23 | |
| 24 | #include <stdlib.h> |
| 25 | #include <string.h> |
| 26 | #include "wx/gifdecod.h" |
| 27 | #include "wx/ptr_scpd.h" |
| 28 | #include "wx/scopeguard.h" |
| 29 | |
| 30 | |
| 31 | |
| 32 | //--------------------------------------------------------------------------- |
| 33 | // GIFImage |
| 34 | //--------------------------------------------------------------------------- |
| 35 | |
| 36 | // internal class for storing GIF image data |
| 37 | class GIFImage |
| 38 | { |
| 39 | public: |
| 40 | // def ctor |
| 41 | GIFImage(); |
| 42 | |
| 43 | unsigned int w; // width |
| 44 | unsigned int h; // height |
| 45 | unsigned int left; // x coord (in logical screen) |
| 46 | unsigned int top; // y coord (in logical screen) |
| 47 | int transparent; // transparent color index (-1 = none) |
| 48 | wxAnimationDisposal disposal; // disposal method |
| 49 | long delay; // delay in ms (-1 = unused) |
| 50 | unsigned char *p; // bitmap |
| 51 | unsigned char *pal; // palette |
| 52 | unsigned int ncolours; // number of colours |
| 53 | |
| 54 | DECLARE_NO_COPY_CLASS(GIFImage) |
| 55 | }; |
| 56 | |
| 57 | wxDECLARE_SCOPED_PTR(GIFImage, GIFImagePtr) |
| 58 | wxDEFINE_SCOPED_PTR(GIFImage, GIFImagePtr) |
| 59 | |
| 60 | |
| 61 | //--------------------------------------------------------------------------- |
| 62 | // GIFImage constructor |
| 63 | //--------------------------------------------------------------------------- |
| 64 | GIFImage::GIFImage() |
| 65 | { |
| 66 | w = 0; |
| 67 | h = 0; |
| 68 | left = 0; |
| 69 | top = 0; |
| 70 | transparent = 0; |
| 71 | disposal = wxANIM_DONOTREMOVE; |
| 72 | delay = -1; |
| 73 | p = (unsigned char *) NULL; |
| 74 | pal = (unsigned char *) NULL; |
| 75 | ncolours = 0; |
| 76 | } |
| 77 | |
| 78 | //--------------------------------------------------------------------------- |
| 79 | // wxGIFDecoder constructor and destructor |
| 80 | //--------------------------------------------------------------------------- |
| 81 | |
| 82 | wxGIFDecoder::wxGIFDecoder() |
| 83 | { |
| 84 | } |
| 85 | |
| 86 | wxGIFDecoder::~wxGIFDecoder() |
| 87 | { |
| 88 | Destroy(); |
| 89 | } |
| 90 | |
| 91 | void wxGIFDecoder::Destroy() |
| 92 | { |
| 93 | wxASSERT(m_nFrames==m_frames.GetCount()); |
| 94 | for (unsigned int i=0; i<m_nFrames; i++) |
| 95 | { |
| 96 | GIFImage *f = (GIFImage*)m_frames[i]; |
| 97 | free(f->p); |
| 98 | free(f->pal); |
| 99 | delete f; |
| 100 | } |
| 101 | |
| 102 | m_frames.Clear(); |
| 103 | m_nFrames = 0; |
| 104 | } |
| 105 | |
| 106 | |
| 107 | //--------------------------------------------------------------------------- |
| 108 | // Convert this image to a wxImage object |
| 109 | //--------------------------------------------------------------------------- |
| 110 | |
| 111 | // This function was designed by Vaclav Slavik |
| 112 | |
| 113 | bool wxGIFDecoder::ConvertToImage(unsigned int frame, wxImage *image) const |
| 114 | { |
| 115 | unsigned char *src, *dst, *pal; |
| 116 | unsigned long i; |
| 117 | int transparent; |
| 118 | |
| 119 | // just in case... |
| 120 | image->Destroy(); |
| 121 | |
| 122 | // create the image |
| 123 | wxSize sz = GetFrameSize(frame); |
| 124 | image->Create(sz.GetWidth(), sz.GetHeight()); |
| 125 | image->SetType(wxBITMAP_TYPE_GIF); |
| 126 | |
| 127 | if (!image->Ok()) |
| 128 | return false; |
| 129 | |
| 130 | pal = GetPalette(frame); |
| 131 | src = GetData(frame); |
| 132 | dst = image->GetData(); |
| 133 | transparent = GetTransparentColourIndex(frame); |
| 134 | |
| 135 | // set transparent colour mask |
| 136 | if (transparent != -1) |
| 137 | { |
| 138 | for (i = 0; i < GetNcolours(frame); i++) |
| 139 | { |
| 140 | if ((pal[3 * i + 0] == 255) && |
| 141 | (pal[3 * i + 1] == 0) && |
| 142 | (pal[3 * i + 2] == 255)) |
| 143 | { |
| 144 | pal[3 * i + 2] = 254; |
| 145 | } |
| 146 | } |
| 147 | |
| 148 | pal[3 * transparent + 0] = 255, |
| 149 | pal[3 * transparent + 1] = 0, |
| 150 | pal[3 * transparent + 2] = 255; |
| 151 | |
| 152 | image->SetMaskColour(255, 0, 255); |
| 153 | } |
| 154 | else |
| 155 | image->SetMask(false); |
| 156 | |
| 157 | #if wxUSE_PALETTE |
| 158 | unsigned char r[256]; |
| 159 | unsigned char g[256]; |
| 160 | unsigned char b[256]; |
| 161 | |
| 162 | for (i = 0; i < 256; i++) |
| 163 | { |
| 164 | r[i] = pal[3*i + 0]; |
| 165 | g[i] = pal[3*i + 1]; |
| 166 | b[i] = pal[3*i + 2]; |
| 167 | } |
| 168 | |
| 169 | image->SetPalette(wxPalette(GetNcolours(frame), r, g, b)); |
| 170 | #endif // wxUSE_PALETTE |
| 171 | |
| 172 | // copy image data |
| 173 | unsigned long npixel = sz.GetWidth() * sz.GetHeight(); |
| 174 | for (i = 0; i < npixel; i++, src++) |
| 175 | { |
| 176 | *(dst++) = pal[3 * (*src) + 0]; |
| 177 | *(dst++) = pal[3 * (*src) + 1]; |
| 178 | *(dst++) = pal[3 * (*src) + 2]; |
| 179 | } |
| 180 | |
| 181 | return true; |
| 182 | } |
| 183 | |
| 184 | |
| 185 | //--------------------------------------------------------------------------- |
| 186 | // Data accessors |
| 187 | //--------------------------------------------------------------------------- |
| 188 | |
| 189 | #define GetFrame(n) ((GIFImage*)m_frames[n]) |
| 190 | |
| 191 | |
| 192 | // Get data for current frame |
| 193 | |
| 194 | wxSize wxGIFDecoder::GetFrameSize(unsigned int frame) const |
| 195 | { |
| 196 | return wxSize(GetFrame(frame)->w, GetFrame(frame)->h); |
| 197 | } |
| 198 | |
| 199 | wxPoint wxGIFDecoder::GetFramePosition(unsigned int frame) const |
| 200 | { |
| 201 | return wxPoint(GetFrame(frame)->left, GetFrame(frame)->top); |
| 202 | } |
| 203 | |
| 204 | wxAnimationDisposal wxGIFDecoder::GetDisposalMethod(unsigned int frame) const |
| 205 | { |
| 206 | return GetFrame(frame)->disposal; |
| 207 | } |
| 208 | |
| 209 | long wxGIFDecoder::GetDelay(unsigned int frame) const |
| 210 | { |
| 211 | return GetFrame(frame)->delay; |
| 212 | } |
| 213 | |
| 214 | wxColour wxGIFDecoder::GetTransparentColour(unsigned int frame) const |
| 215 | { |
| 216 | unsigned char *pal = GetFrame(frame)->pal; |
| 217 | int n = GetFrame(frame)->transparent; |
| 218 | if (n == -1) |
| 219 | return wxNullColour; |
| 220 | |
| 221 | return wxColour(pal[n*3 + 0], |
| 222 | pal[n*3 + 1], |
| 223 | pal[n*3 + 2]); |
| 224 | } |
| 225 | |
| 226 | unsigned char* wxGIFDecoder::GetData(unsigned int frame) const { return (GetFrame(frame)->p); } |
| 227 | unsigned char* wxGIFDecoder::GetPalette(unsigned int frame) const { return (GetFrame(frame)->pal); } |
| 228 | unsigned int wxGIFDecoder::GetNcolours(unsigned int frame) const { return (GetFrame(frame)->ncolours); } |
| 229 | int wxGIFDecoder::GetTransparentColourIndex(unsigned int frame) const { return (GetFrame(frame)->transparent); } |
| 230 | |
| 231 | |
| 232 | |
| 233 | //--------------------------------------------------------------------------- |
| 234 | // GIF reading and decoding |
| 235 | //--------------------------------------------------------------------------- |
| 236 | |
| 237 | // getcode: |
| 238 | // Reads the next code from the file stream, with size 'bits' |
| 239 | // |
| 240 | int wxGIFDecoder::getcode(wxInputStream& stream, int bits, int ab_fin) |
| 241 | { |
| 242 | unsigned int mask; // bit mask |
| 243 | unsigned int code; // code (result) |
| 244 | |
| 245 | // get remaining bits from last byte read |
| 246 | mask = (1 << bits) - 1; |
| 247 | code = (m_lastbyte >> (8 - m_restbits)) & mask; |
| 248 | |
| 249 | // keep reading new bytes while needed |
| 250 | while (bits > m_restbits) |
| 251 | { |
| 252 | // if no bytes left in this block, read the next block |
| 253 | if (m_restbyte == 0) |
| 254 | { |
| 255 | m_restbyte = (unsigned char)stream.GetC(); |
| 256 | |
| 257 | /* Some encoders are a bit broken: instead of issuing |
| 258 | * an end-of-image symbol (ab_fin) they come up with |
| 259 | * a zero-length subblock!! We catch this here so |
| 260 | * that the decoder sees an ab_fin code. |
| 261 | */ |
| 262 | if (m_restbyte == 0) |
| 263 | { |
| 264 | code = ab_fin; |
| 265 | break; |
| 266 | } |
| 267 | |
| 268 | // prefetch data |
| 269 | stream.Read((void *) m_buffer, m_restbyte); |
| 270 | if (stream.LastRead() != m_restbyte) |
| 271 | { |
| 272 | code = ab_fin; |
| 273 | return code; |
| 274 | } |
| 275 | m_bufp = m_buffer; |
| 276 | } |
| 277 | |
| 278 | // read next byte and isolate the bits we need |
| 279 | m_lastbyte = (unsigned char) (*m_bufp++); |
| 280 | mask = (1 << (bits - m_restbits)) - 1; |
| 281 | code = code + ((m_lastbyte & mask) << m_restbits); |
| 282 | m_restbyte--; |
| 283 | |
| 284 | // adjust total number of bits extracted from the buffer |
| 285 | m_restbits = m_restbits + 8; |
| 286 | } |
| 287 | |
| 288 | // find number of bits remaining for next code |
| 289 | m_restbits = (m_restbits - bits); |
| 290 | |
| 291 | return code; |
| 292 | } |
| 293 | |
| 294 | |
| 295 | // dgif: |
| 296 | // GIF decoding function. The initial code size (aka root size) |
| 297 | // is 'bits'. Supports interlaced images (interl == 1). |
| 298 | // Returns wxGIF_OK (== 0) on success, or an error code if something |
| 299 | // fails (see header file for details) |
| 300 | wxGIFErrorCode |
| 301 | wxGIFDecoder::dgif(wxInputStream& stream, GIFImage *img, int interl, int bits) |
| 302 | { |
| 303 | static const int allocSize = 4096 + 1; |
| 304 | int *ab_prefix = new int[allocSize]; // alphabet (prefixes) |
| 305 | if (ab_prefix == NULL) |
| 306 | { |
| 307 | return wxGIF_MEMERR; |
| 308 | } |
| 309 | |
| 310 | int *ab_tail = new int[allocSize]; // alphabet (tails) |
| 311 | if (ab_tail == NULL) |
| 312 | { |
| 313 | delete[] ab_prefix; |
| 314 | return wxGIF_MEMERR; |
| 315 | } |
| 316 | |
| 317 | int *stack = new int[allocSize]; // decompression stack |
| 318 | if (stack == NULL) |
| 319 | { |
| 320 | delete[] ab_prefix; |
| 321 | delete[] ab_tail; |
| 322 | return wxGIF_MEMERR; |
| 323 | } |
| 324 | |
| 325 | int ab_clr; // clear code |
| 326 | int ab_fin; // end of info code |
| 327 | int ab_bits; // actual symbol width, in bits |
| 328 | int ab_free; // first free position in alphabet |
| 329 | int ab_max; // last possible character in alphabet |
| 330 | int pass; // pass number in interlaced images |
| 331 | int pos; // index into decompresion stack |
| 332 | unsigned int x, y; // position in image buffer |
| 333 | |
| 334 | int code, readcode, lastcode, abcabca; |
| 335 | |
| 336 | // these won't change |
| 337 | ab_clr = (1 << bits); |
| 338 | ab_fin = (1 << bits) + 1; |
| 339 | |
| 340 | // these will change through the decompression proccess |
| 341 | ab_bits = bits + 1; |
| 342 | ab_free = (1 << bits) + 2; |
| 343 | ab_max = (1 << ab_bits) - 1; |
| 344 | lastcode = -1; |
| 345 | abcabca = -1; |
| 346 | pass = 1; |
| 347 | pos = x = y = 0; |
| 348 | |
| 349 | // reset decoder vars |
| 350 | m_restbits = 0; |
| 351 | m_restbyte = 0; |
| 352 | m_lastbyte = 0; |
| 353 | |
| 354 | do |
| 355 | { |
| 356 | // get next code |
| 357 | readcode = code = getcode(stream, ab_bits, ab_fin); |
| 358 | |
| 359 | // end of image? |
| 360 | if (code == ab_fin) break; |
| 361 | |
| 362 | // reset alphabet? |
| 363 | if (code == ab_clr) |
| 364 | { |
| 365 | // reset main variables |
| 366 | ab_bits = bits + 1; |
| 367 | ab_free = (1 << bits) + 2; |
| 368 | ab_max = (1 << ab_bits) - 1; |
| 369 | lastcode = -1; |
| 370 | abcabca = -1; |
| 371 | |
| 372 | // skip to next code |
| 373 | continue; |
| 374 | } |
| 375 | |
| 376 | // unknown code: special case (like in ABCABCA) |
| 377 | if (code >= ab_free) |
| 378 | { |
| 379 | code = lastcode; // take last string |
| 380 | stack[pos++] = abcabca; // add first character |
| 381 | } |
| 382 | |
| 383 | // build the string for this code in the stack |
| 384 | while (code > ab_clr) |
| 385 | { |
| 386 | stack[pos++] = ab_tail[code]; |
| 387 | code = ab_prefix[code]; |
| 388 | |
| 389 | // Don't overflow. This shouldn't happen with normal |
| 390 | // GIF files, the allocSize of 4096+1 is enough. This |
| 391 | // will only happen with badly formed GIFs. |
| 392 | if (pos >= allocSize) |
| 393 | { |
| 394 | delete[] ab_prefix; |
| 395 | delete[] ab_tail; |
| 396 | delete[] stack; |
| 397 | return wxGIF_INVFORMAT; |
| 398 | } |
| 399 | } |
| 400 | |
| 401 | if (pos >= allocSize) |
| 402 | { |
| 403 | delete[] ab_prefix; |
| 404 | delete[] ab_tail; |
| 405 | delete[] stack; |
| 406 | return wxGIF_INVFORMAT; |
| 407 | } |
| 408 | |
| 409 | stack[pos] = code; // push last code into the stack |
| 410 | abcabca = code; // save for special case |
| 411 | |
| 412 | // make new entry in alphabet (only if NOT just cleared) |
| 413 | if (lastcode != -1) |
| 414 | { |
| 415 | // Normally, after the alphabet is full and can't grow any |
| 416 | // further (ab_free == 4096), encoder should (must?) emit CLEAR |
| 417 | // to reset it. This checks whether we really got it, otherwise |
| 418 | // the GIF is damaged. |
| 419 | if (ab_free > ab_max) |
| 420 | { |
| 421 | delete[] ab_prefix; |
| 422 | delete[] ab_tail; |
| 423 | delete[] stack; |
| 424 | return wxGIF_INVFORMAT; |
| 425 | } |
| 426 | |
| 427 | // This assert seems unnecessary since the condition above |
| 428 | // eliminates the only case in which it went false. But I really |
| 429 | // don't like being forced to ask "Who in .text could have |
| 430 | // written there?!" And I wouldn't have been forced to ask if |
| 431 | // this line had already been here. |
| 432 | wxASSERT(ab_free < allocSize); |
| 433 | |
| 434 | ab_prefix[ab_free] = lastcode; |
| 435 | ab_tail[ab_free] = code; |
| 436 | ab_free++; |
| 437 | |
| 438 | if ((ab_free > ab_max) && (ab_bits < 12)) |
| 439 | { |
| 440 | ab_bits++; |
| 441 | ab_max = (1 << ab_bits) - 1; |
| 442 | } |
| 443 | } |
| 444 | |
| 445 | // dump stack data to the image buffer |
| 446 | while (pos >= 0) |
| 447 | { |
| 448 | (img->p)[x + (y * (img->w))] = (char) stack[pos]; |
| 449 | pos--; |
| 450 | |
| 451 | if (++x >= (img->w)) |
| 452 | { |
| 453 | x = 0; |
| 454 | |
| 455 | if (interl) |
| 456 | { |
| 457 | // support for interlaced images |
| 458 | switch (pass) |
| 459 | { |
| 460 | case 1: y += 8; break; |
| 461 | case 2: y += 8; break; |
| 462 | case 3: y += 4; break; |
| 463 | case 4: y += 2; break; |
| 464 | } |
| 465 | |
| 466 | /* loop until a valid y coordinate has been |
| 467 | found, Or if the maximum number of passes has |
| 468 | been reached, exit the loop, and stop image |
| 469 | decoding (At this point the image is successfully |
| 470 | decoded). |
| 471 | If we don't loop, but merely set y to some other |
| 472 | value, that new value might still be invalid depending |
| 473 | on the height of the image. This would cause out of |
| 474 | bounds writing. |
| 475 | */ |
| 476 | while (y >= (img->h)) |
| 477 | { |
| 478 | switch (++pass) |
| 479 | { |
| 480 | case 2: y = 4; break; |
| 481 | case 3: y = 2; break; |
| 482 | case 4: y = 1; break; |
| 483 | |
| 484 | default: |
| 485 | /* |
| 486 | It's possible we arrive here. For example this |
| 487 | happens when the image is interlaced, and the |
| 488 | height is 1. Looking at the above cases, the |
| 489 | lowest possible y is 1. While the only valid |
| 490 | one would be 0 for an image of height 1. So |
| 491 | 'eventually' the loop will arrive here. |
| 492 | This case makes sure this while loop is |
| 493 | exited, as well as the 2 other ones. |
| 494 | */ |
| 495 | |
| 496 | // Set y to a valid coordinate so the local |
| 497 | // while loop will be exited. (y = 0 always |
| 498 | // is >= img->h since if img->h == 0 the |
| 499 | // image is never decoded) |
| 500 | y = 0; |
| 501 | |
| 502 | // This will exit the other outer while loop |
| 503 | pos = -1; |
| 504 | |
| 505 | // This will halt image decoding. |
| 506 | code = ab_fin; |
| 507 | |
| 508 | break; |
| 509 | } |
| 510 | } |
| 511 | } |
| 512 | else |
| 513 | { |
| 514 | // non-interlaced |
| 515 | y++; |
| 516 | /* |
| 517 | Normally image decoding is finished when an End of Information code is |
| 518 | encountered (code == ab_fin) however some broken encoders write wrong |
| 519 | "block byte counts" (The first byte value after the "code size" byte), |
| 520 | being one value too high. It might very well be possible other variants |
| 521 | of this problem occur as well. The only sensible solution seems to |
| 522 | be to check for clipping. |
| 523 | Example of wrong encoding: |
| 524 | (1 * 1 B/W image, raster data stream follows in hex bytes) |
| 525 | |
| 526 | 02 << B/W images have a code size of 2 |
| 527 | 02 << Block byte count |
| 528 | 44 << LZW packed |
| 529 | 00 << Zero byte count (terminates data stream) |
| 530 | |
| 531 | Because the block byte count is 2, the zero byte count is used in the |
| 532 | decoding process, and decoding is continued after this byte. (While it |
| 533 | should signal an end of image) |
| 534 | |
| 535 | It should be: |
| 536 | 02 |
| 537 | 02 |
| 538 | 44 |
| 539 | 01 << When decoded this correctly includes the End of Information code |
| 540 | 00 |
| 541 | |
| 542 | Or (Worse solution): |
| 543 | 02 |
| 544 | 01 |
| 545 | 44 |
| 546 | 00 |
| 547 | (The 44 doesn't include an End of Information code, but at least the |
| 548 | decoder correctly skips to 00 now after decoding, and signals this |
| 549 | as an End of Information itself) |
| 550 | */ |
| 551 | if (y >= img->h) |
| 552 | { |
| 553 | code = ab_fin; |
| 554 | break; |
| 555 | } |
| 556 | } |
| 557 | } |
| 558 | } |
| 559 | |
| 560 | pos = 0; |
| 561 | lastcode = readcode; |
| 562 | } |
| 563 | while (code != ab_fin); |
| 564 | |
| 565 | delete [] ab_prefix ; |
| 566 | delete [] ab_tail ; |
| 567 | delete [] stack ; |
| 568 | |
| 569 | return wxGIF_OK; |
| 570 | } |
| 571 | |
| 572 | |
| 573 | // CanRead: |
| 574 | // Returns true if the file looks like a valid GIF, false otherwise. |
| 575 | // |
| 576 | bool wxGIFDecoder::CanRead(wxInputStream &stream) const |
| 577 | { |
| 578 | unsigned char buf[3]; |
| 579 | |
| 580 | if ( !stream.Read(buf, WXSIZEOF(buf)) ) |
| 581 | return false; |
| 582 | |
| 583 | stream.SeekI(-(wxFileOffset)WXSIZEOF(buf), wxFromCurrent); |
| 584 | |
| 585 | return memcmp(buf, "GIF", WXSIZEOF(buf)) == 0; |
| 586 | } |
| 587 | |
| 588 | |
| 589 | // LoadGIF: |
| 590 | // Reads and decodes one or more GIF images, depending on whether |
| 591 | // animated GIF support is enabled. Can read GIFs with any bit |
| 592 | // size (color depth), but the output images are always expanded |
| 593 | // to 8 bits per pixel. Also, the image palettes always contain |
| 594 | // 256 colors, although some of them may be unused. Returns wxGIF_OK |
| 595 | // (== 0) on success, or an error code if something fails (see |
| 596 | // header file for details) |
| 597 | // |
| 598 | wxGIFErrorCode wxGIFDecoder::LoadGIF(wxInputStream& stream) |
| 599 | { |
| 600 | unsigned int global_ncolors = 0; |
| 601 | int bits, interl, i; |
| 602 | wxAnimationDisposal disposal; |
| 603 | long size; |
| 604 | long delay; |
| 605 | unsigned char type = 0; |
| 606 | unsigned char pal[768]; |
| 607 | unsigned char buf[16]; |
| 608 | bool anim = true; |
| 609 | |
| 610 | // check GIF signature |
| 611 | if (!CanRead(stream)) |
| 612 | return wxGIF_INVFORMAT; |
| 613 | |
| 614 | // check for animated GIF support (ver. >= 89a) |
| 615 | |
| 616 | static const unsigned int headerSize = (3 + 3); |
| 617 | stream.Read(buf, headerSize); |
| 618 | if (stream.LastRead() != headerSize) |
| 619 | { |
| 620 | return wxGIF_INVFORMAT; |
| 621 | } |
| 622 | |
| 623 | if (memcmp(buf + 3, "89a", 3) < 0) |
| 624 | { |
| 625 | anim = false; |
| 626 | } |
| 627 | |
| 628 | // read logical screen descriptor block (LSDB) |
| 629 | static const unsigned int lsdbSize = (2 + 2 + 1 + 1 + 1); |
| 630 | stream.Read(buf, lsdbSize); |
| 631 | if (stream.LastRead() != lsdbSize) |
| 632 | { |
| 633 | return wxGIF_INVFORMAT; |
| 634 | } |
| 635 | |
| 636 | m_szAnimation.SetWidth( buf[0] + 256 * buf[1] ); |
| 637 | m_szAnimation.SetHeight( buf[2] + 256 * buf[3] ); |
| 638 | |
| 639 | if (anim && ((m_szAnimation.GetWidth() == 0) || (m_szAnimation.GetHeight() == 0))) |
| 640 | { |
| 641 | return wxGIF_INVFORMAT; |
| 642 | } |
| 643 | |
| 644 | // load global color map if available |
| 645 | if ((buf[4] & 0x80) == 0x80) |
| 646 | { |
| 647 | int backgroundColIndex = buf[5]; |
| 648 | |
| 649 | global_ncolors = 2 << (buf[4] & 0x07); |
| 650 | unsigned int numBytes = 3 * global_ncolors; |
| 651 | stream.Read(pal, numBytes); |
| 652 | if (stream.LastRead() != numBytes) |
| 653 | { |
| 654 | return wxGIF_INVFORMAT; |
| 655 | } |
| 656 | |
| 657 | m_background.Set(pal[backgroundColIndex*3 + 0], |
| 658 | pal[backgroundColIndex*3 + 1], |
| 659 | pal[backgroundColIndex*3 + 2]); |
| 660 | } |
| 661 | |
| 662 | // transparent colour, disposal method and delay default to unused |
| 663 | int transparent = -1; |
| 664 | disposal = wxANIM_UNSPECIFIED; |
| 665 | delay = -1; |
| 666 | |
| 667 | bool done = false; |
| 668 | while (!done) |
| 669 | { |
| 670 | type = (unsigned char)stream.GetC(); |
| 671 | |
| 672 | /* |
| 673 | If the end of file has been reached (or an error) and a ";" |
| 674 | (0x3B) hasn't been encountered yet, exit the loop. (Without this |
| 675 | check the while loop would loop endlessly.) Later on, in the next while |
| 676 | loop, the file will be treated as being truncated (But still |
| 677 | be decoded as far as possible). returning wxGIF_TRUNCATED is not |
| 678 | possible here since some init code is done after this loop. |
| 679 | */ |
| 680 | if (stream.Eof())// || !stream.IsOk()) |
| 681 | { |
| 682 | /* |
| 683 | type is set to some bogus value, so there's no |
| 684 | need to continue evaluating it. |
| 685 | */ |
| 686 | break; // Alternative : "return wxGIF_INVFORMAT;" |
| 687 | } |
| 688 | |
| 689 | // end of data? |
| 690 | if (type == 0x3B) |
| 691 | { |
| 692 | done = true; |
| 693 | } |
| 694 | else |
| 695 | // extension block? |
| 696 | if (type == 0x21) |
| 697 | { |
| 698 | if (((unsigned char)stream.GetC()) == 0xF9) |
| 699 | // graphics control extension, parse it |
| 700 | { |
| 701 | static const unsigned int gceSize = 6; |
| 702 | stream.Read(buf, gceSize); |
| 703 | if (stream.LastRead() != gceSize) |
| 704 | { |
| 705 | Destroy(); |
| 706 | return wxGIF_INVFORMAT; |
| 707 | } |
| 708 | |
| 709 | // read delay and convert from 1/100 of a second to ms |
| 710 | delay = 10 * (buf[2] + 256 * buf[3]); |
| 711 | |
| 712 | // read transparent colour index, if used |
| 713 | transparent = buf[1] & 0x01 ? buf[4] : -1; |
| 714 | |
| 715 | // read disposal method |
| 716 | disposal = (wxAnimationDisposal)(((buf[1] & 0x1C) >> 2) - 1); |
| 717 | } |
| 718 | else |
| 719 | // other extension, skip |
| 720 | { |
| 721 | while ((i = (unsigned char)stream.GetC()) != 0) |
| 722 | { |
| 723 | if (stream.Eof() || (stream.LastRead() == 0)) |
| 724 | { |
| 725 | done = true; |
| 726 | break; |
| 727 | } |
| 728 | stream.SeekI(i, wxFromCurrent); |
| 729 | } |
| 730 | } |
| 731 | } |
| 732 | else |
| 733 | // image descriptor block? |
| 734 | if (type == 0x2C) |
| 735 | { |
| 736 | // allocate memory for IMAGEN struct |
| 737 | GIFImagePtr pimg(new GIFImage()); |
| 738 | |
| 739 | wxScopeGuard guardDestroy = wxMakeObjGuard(*this, &wxGIFDecoder::Destroy); |
| 740 | |
| 741 | if ( !pimg.get() ) |
| 742 | return wxGIF_MEMERR; |
| 743 | |
| 744 | // fill in the data |
| 745 | static const unsigned int idbSize = (2 + 2 + 2 + 2 + 1); |
| 746 | stream.Read(buf, idbSize); |
| 747 | if (stream.LastRead() != idbSize) |
| 748 | return wxGIF_INVFORMAT; |
| 749 | |
| 750 | pimg->left = buf[0] + 256 * buf[1]; |
| 751 | pimg->top = buf[2] + 256 * buf[3]; |
| 752 | /* |
| 753 | pimg->left = buf[4] + 256 * buf[5]; |
| 754 | pimg->top = buf[4] + 256 * buf[5]; |
| 755 | */ |
| 756 | pimg->w = buf[4] + 256 * buf[5]; |
| 757 | pimg->h = buf[6] + 256 * buf[7]; |
| 758 | |
| 759 | if ( anim && ((pimg->w == 0) || (pimg->w > (unsigned int)m_szAnimation.GetWidth()) || |
| 760 | (pimg->h == 0) || (pimg->h > (unsigned int)m_szAnimation.GetHeight())) ) |
| 761 | return wxGIF_INVFORMAT; |
| 762 | |
| 763 | interl = ((buf[8] & 0x40)? 1 : 0); |
| 764 | size = pimg->w * pimg->h; |
| 765 | |
| 766 | pimg->transparent = transparent; |
| 767 | pimg->disposal = disposal; |
| 768 | pimg->delay = delay; |
| 769 | |
| 770 | // allocate memory for image and palette |
| 771 | pimg->p = (unsigned char *) malloc((unsigned int)size); |
| 772 | pimg->pal = (unsigned char *) malloc(768); |
| 773 | |
| 774 | if ((!pimg->p) || (!pimg->pal)) |
| 775 | return wxGIF_MEMERR; |
| 776 | |
| 777 | // load local color map if available, else use global map |
| 778 | if ((buf[8] & 0x80) == 0x80) |
| 779 | { |
| 780 | unsigned int local_ncolors = 2 << (buf[8] & 0x07); |
| 781 | unsigned int numBytes = 3 * local_ncolors; |
| 782 | stream.Read(pimg->pal, numBytes); |
| 783 | pimg->ncolours = local_ncolors; |
| 784 | if (stream.LastRead() != numBytes) |
| 785 | return wxGIF_INVFORMAT; |
| 786 | } |
| 787 | else |
| 788 | { |
| 789 | memcpy(pimg->pal, pal, 768); |
| 790 | pimg->ncolours = global_ncolors; |
| 791 | } |
| 792 | |
| 793 | // get initial code size from first byte in raster data |
| 794 | bits = (unsigned char)stream.GetC(); |
| 795 | if (bits == 0) |
| 796 | return wxGIF_INVFORMAT; |
| 797 | |
| 798 | // decode image |
| 799 | wxGIFErrorCode result = dgif(stream, pimg.get(), interl, bits); |
| 800 | if (result != wxGIF_OK) |
| 801 | return result; |
| 802 | |
| 803 | guardDestroy.Dismiss(); |
| 804 | |
| 805 | // add the image to our frame array |
| 806 | m_frames.Add(pimg.release()); |
| 807 | m_nFrames++; |
| 808 | |
| 809 | // if this is not an animated GIF, exit after first image |
| 810 | if (!anim) |
| 811 | done = true; |
| 812 | } |
| 813 | } |
| 814 | |
| 815 | if (m_nFrames <= 0) |
| 816 | { |
| 817 | Destroy(); |
| 818 | return wxGIF_INVFORMAT; |
| 819 | } |
| 820 | |
| 821 | // try to read to the end of the stream |
| 822 | while (type != 0x3B) |
| 823 | { |
| 824 | if (!stream.IsOk()) |
| 825 | return wxGIF_TRUNCATED; |
| 826 | |
| 827 | type = (unsigned char)stream.GetC(); |
| 828 | |
| 829 | if (type == 0x21) |
| 830 | { |
| 831 | // extension type |
| 832 | (void) stream.GetC(); |
| 833 | |
| 834 | // skip all data |
| 835 | while ((i = (unsigned char)stream.GetC()) != 0) |
| 836 | { |
| 837 | if (stream.Eof() || (stream.LastRead() == 0)) |
| 838 | { |
| 839 | Destroy(); |
| 840 | return wxGIF_INVFORMAT; |
| 841 | } |
| 842 | stream.SeekI(i, wxFromCurrent); |
| 843 | } |
| 844 | } |
| 845 | else if (type == 0x2C) |
| 846 | { |
| 847 | // image descriptor block |
| 848 | static const unsigned int idbSize = (2 + 2 + 2 + 2 + 1); |
| 849 | stream.Read(buf, idbSize); |
| 850 | if (stream.LastRead() != idbSize) |
| 851 | { |
| 852 | Destroy(); |
| 853 | return wxGIF_INVFORMAT; |
| 854 | } |
| 855 | |
| 856 | // local color map |
| 857 | if ((buf[8] & 0x80) == 0x80) |
| 858 | { |
| 859 | unsigned int local_ncolors = 2 << (buf[8] & 0x07); |
| 860 | wxFileOffset numBytes = 3 * local_ncolors; |
| 861 | stream.SeekI(numBytes, wxFromCurrent); |
| 862 | } |
| 863 | |
| 864 | // initial code size |
| 865 | (void) stream.GetC(); |
| 866 | if (stream.Eof() || (stream.LastRead() == 0)) |
| 867 | { |
| 868 | Destroy(); |
| 869 | return wxGIF_INVFORMAT; |
| 870 | } |
| 871 | |
| 872 | // skip all data |
| 873 | while ((i = (unsigned char)stream.GetC()) != 0) |
| 874 | { |
| 875 | if (stream.Eof() || (stream.LastRead() == 0)) |
| 876 | { |
| 877 | Destroy(); |
| 878 | return wxGIF_INVFORMAT; |
| 879 | } |
| 880 | stream.SeekI(i, wxFromCurrent); |
| 881 | } |
| 882 | } |
| 883 | else if ((type != 0x3B) && (type != 00)) // testing |
| 884 | { |
| 885 | // images are OK, but couldn't read to the end of the stream |
| 886 | return wxGIF_TRUNCATED; |
| 887 | } |
| 888 | } |
| 889 | |
| 890 | return wxGIF_OK; |
| 891 | } |
| 892 | |
| 893 | #endif // wxUSE_STREAMS && wxUSE_GIF |