src/common/gifdecod.cpp

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