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 #ifdef __WXMAC__
 337     int *ab_prefix = new int[4096];        /* alphabet (prefixes) */
 338     int *ab_tail = new int[4096];          /* alphabet (tails) */
 339     int *stack = new int[4096];            /* decompression stack */
 340 #else
 341     int ab_prefix[4096];        /* alphabet (prefixes) */
 342     int ab_tail[4096];          /* alphabet (tails) */
 343     int stack[4096];            /* decompression stack */
 344 #endif
 345     int ab_clr;                 /* clear code */
 346     int ab_fin;                 /* end of info code */
 347     int ab_bits;                /* actual symbol width, in bits */
 348     int ab_free;                /* first free position in alphabet */
 349     int ab_max;                 /* last possible character in alphabet */
 350     int pass;                   /* pass number in interlaced images */
 351     int pos;                    /* index into decompresion stack */
 352     unsigned int x, y;          /* position in image buffer */
 353
 354     int code, readcode, lastcode, abcabca;
 355
 356     /* these won't change */
 357     ab_clr = (1 << bits);
 358     ab_fin = (1 << bits) + 1;
 359
 360     /* these will change through the decompression proccess */
 361     ab_bits  = bits + 1;
 362     ab_free  = (1 << bits) + 2;
 363     ab_max   = (1 << ab_bits) - 1;
 364     lastcode = -1;
 365     abcabca  = -1;
 366     pass     = 1;
 367     pos = x = y = 0;
 368
 369     /* reset decoder vars */
 370     m_restbits = 0;
 371     m_restbyte = 0;
 372     m_lastbyte = 0;
 373
 374     do
 375     {
 376         /* get next code */
 377         readcode = code = getcode(ab_bits, ab_fin);
 378
 379         /* end of image? */
 380         if (code == ab_fin) break;
 381
 382         /* reset alphabet? */
 383         if (code == ab_clr)
 384         {
 385             /* reset main variables */
 386             ab_bits  = bits + 1;
 387             ab_free  = (1 << bits) + 2;
 388             ab_max   = (1 << ab_bits) - 1;
 389             lastcode = -1;
 390             abcabca  = -1;
 391
 392             /* skip to next code */
 393             continue;
 394         }
 395
 396         /* unknown code: special case (like in ABCABCA) */
 397         if (code >= ab_free)
 398         {
 399             code = lastcode;            /* take last string */
 400             stack[pos++] = abcabca;     /* add first character */
 401         }
 402
 403         /* build the string for this code in the stack */
 404         while (code > ab_clr)
 405         {
 406             stack[pos++] = ab_tail[code];
 407             code         = ab_prefix[code];
 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             ab_prefix[ab_free] = lastcode;
 416             ab_tail[ab_free]   = code;
 417             ab_free++;
 418
 419             if ((ab_free > ab_max) && (ab_bits < 12))
 420             {
 421                 ab_bits++;
 422                 ab_max = (1 << ab_bits) - 1;
 423             }
 424         }
 425
 426         /* dump stack data to the buffer */
 427         while (pos >= 0)
 428         {
 429             (img->p)[x + (y * (img->w))] = (char)stack[pos--];
 430
 431             if (++x >= (img->w))
 432             {
 433                 x = 0;
 434
 435                 if (interl)
 436                 {
 437                     /* support for interlaced images */
 438                     switch (pass)
 439                     {
 440                         case 1: y += 8; break;
 441                         case 2: y += 8; break;
 442                         case 3: y += 4; break;
 443                         case 4: y += 2; break;
 444                     }
 445                     if (y >= (img->h))
 446                     {
 447                         switch (++pass)
 448                         {
 449                             case 2: y = 4; break;
 450                             case 3: y = 2; break;
 451                             case 4: y = 1; break;
 452                         }
 453                     }
 454                 }
 455                 else
 456                 {
 457                     /* non-interlaced */
 458                     y++;
 459                 }
 460             }
 461         }
 462
 463         pos = 0;
 464         lastcode = readcode;
 465     }
 466     while (code != ab_fin);
 467
 468 #ifdef __WXMAC__
 469     delete [] ab_prefix ;
 470     delete [] ab_tail ;
 471     delete [] stack ;
 472 #endif
 473     return 0;
 474 }
 475
 476
 477 // CanRead:
 478 //  Returns TRUE if the file looks like a valid GIF, FALSE otherwise.
 479 //
 480 bool wxGIFDecoder::CanRead()
 481 {
 482     unsigned char buf[3];
 483
 484     m_f->Read(buf, 3);
 485     m_f->SeekI(-3, wxFromCurrent);
 486
 487     return (memcmp(buf, "GIF", 3) == 0);
 488 }
 489
 490
 491 // ReadGIF:
 492 //  Reads and decodes one or more GIF images, depending on whether
 493 //  animated GIF support is enabled. Can read GIFs with any bit
 494 //  size (color depth), but the output images are always expanded
 495 //  to 8 bits per pixel. Also, the image palettes always contain
 496 //  256 colors, although some of them may be unused. Returns wxGIF_OK
 497 //  (== 0) on success, or an error code if something fails (see
 498 //  header file for details)
 499 //
 500 int wxGIFDecoder::ReadGIF()
 501 {
 502     int           ncolors, bits, interl, transparent, disposal, i;
 503     long          size;
 504     long          delay;
 505     unsigned char type = 0;
 506     unsigned char pal[768];
 507     unsigned char buf[16];
 508     GIFImage      **ppimg, *pimg, *pprev;
 509
 510     /* check GIF signature */
 511     if (!CanRead())
 512         return wxGIF_INVFORMAT;
 513
 514     /* check for animated GIF support (ver. >= 89a) */
 515     m_f->Read(buf, 6);
 516
 517     if (memcmp(buf + 3, "89a", 3) < 0)
 518         m_anim = FALSE;
 519
 520     /* read logical screen descriptor block (LSDB) */
 521     m_f->Read(buf, 7);
 522     m_screenw = buf[0] + 256 * buf[1];
 523     m_screenh = buf[2] + 256 * buf[3];
 524
 525     /* load global color map if available */
 526     if ((buf[4] & 0x80) == 0x80)
 527     {
 528         m_background = buf[5];
 529
 530         ncolors = 2 << (buf[4] & 0x07);
 531         m_f->Read(pal, 3 * ncolors);
 532     }
 533
 534     /* transparent colour, disposal method and delay default to unused */
 535     transparent = -1;
 536     disposal = -1;
 537     delay = -1;
 538
 539     /* read images */
 540     ppimg = &m_pfirst;
 541     pprev = NULL;
 542     pimg  = NULL;
 543
 544     bool done = FALSE;
 545
 546     while(!done)
 547     {
 548         type = (unsigned char)m_f->GetC();
 549
 550         /* end of data? */
 551         if (type == 0x3B)
 552         {
 553             done = TRUE;
 554         }
 555         else
 556         /* extension block? */
 557         if (type == 0x21)
 558         {
 559             if (((unsigned char)m_f->GetC()) == 0xF9)
 560             /* graphics control extension, parse it */
 561             {
 562                 m_f->Read(buf, 6);
 563
 564                 /* read delay and convert from 1/100 of a second to ms */
 565                 delay = 10 * (buf[2] + 256 * buf[3]);
 566
 567                 /* read transparent colour index, if used */
 568                 if (buf[1] & 0x01)
 569                     transparent = buf[4];
 570
 571                 /* read disposal method */
 572                 disposal = (buf[1] & 0x1C) - 1;
 573             }
 574             else
 575             /* other extension, skip */
 576             {
 577                 while ((i = (unsigned char)m_f->GetC()) != 0)
 578                 {
 579                     m_f->SeekI(i, wxFromCurrent);
 580                 }
 581             }
 582         }
 583         else
 584         /* image descriptor block? */
 585         if (type == 0x2C)
 586         {
 587             /* allocate memory for IMAGEN struct */
 588             pimg = (*ppimg) = new GIFImage();
 589
 590             if (pimg == NULL)
 591             {
 592                 Destroy();
 593                 return wxGIF_MEMERR;
 594             }
 595
 596             /* fill in the data */
 597             m_f->Read(buf, 9);
 598             pimg->left = buf[4] + 256 * buf[5];
 599             pimg->top = buf[4] + 256 * buf[5];
 600             pimg->w = buf[4] + 256 * buf[5];
 601             pimg->h = buf[6] + 256 * buf[7];
 602             interl = ((buf[8] & 0x40)? 1 : 0);
 603             size = pimg->w * pimg->h;
 604
 605             pimg->transparent = transparent;
 606             pimg->disposal = disposal;
 607             pimg->delay = delay;
 608             pimg->next = NULL;
 609             pimg->prev = pprev;
 610             pprev = pimg;
 611             ppimg = &pimg->next;
 612
 613             /* allocate memory for image and palette */
 614             pimg->p   = (unsigned char *) malloc((size_t)size);
 615             pimg->pal = (unsigned char *) malloc(768);
 616
 617             if ((!pimg->p) || (!pimg->pal))
 618             {
 619                 Destroy();
 620                 return wxGIF_MEMERR;
 621             }
 622
 623             /* load local color map if available, else use global map */
 624             if ((buf[8] & 0x80) == 0x80)
 625             {
 626                 ncolors = 2 << (buf[8] & 0x07);
 627                 m_f->Read(pimg->pal, 3 * ncolors);
 628             }
 629             else
 630                 memcpy(pimg->pal, pal, 768);
 631
 632             /* get initial code size from first byte in raster data */
 633             bits = (unsigned char)m_f->GetC();
 634
 635             /* decode image */
 636             dgif(pimg, interl, bits);
 637             m_nimages++;
 638
 639             /* if this is not an animated GIF, exit after first image */
 640             if (!m_anim)
 641                 done = TRUE;
 642         }
 643     }
 644
 645     /* setup image pointers */
 646     if (m_nimages != 0)
 647     {
 648         m_image = 1;
 649         m_plast = pimg;
 650         m_pimage = m_pfirst;
 651     }
 652
 653     /* try to read to the end of the stream */
 654     while (type != 0x3B)
 655     {
 656         type = (unsigned char)m_f->GetC();
 657
 658         if (type == 0x21)
 659         {
 660             /* extension type */
 661             (void) m_f->GetC();
 662
 663             /* skip all data */
 664             while ((i = (unsigned char)m_f->GetC()) != 0)
 665             {
 666                 m_f->SeekI(i, wxFromCurrent);
 667             }
 668         }
 669         else if (type == 0x2C)
 670         {
 671             /* image descriptor block */
 672             m_f->Read(buf, 9);
 673
 674             /* local color map */
 675             if ((buf[8] & 0x80) == 0x80)
 676             {
 677                 ncolors = 2 << (buf[8] & 0x07);
 678                 m_f->SeekI(3 * ncolors, wxFromCurrent);
 679             }
 680
 681             /* initial code size */
 682             (void) m_f->GetC();
 683
 684             /* skip all data */
 685             while ((i = (unsigned char)m_f->GetC()) != 0)
 686             {
 687                 m_f->SeekI(i, wxFromCurrent);
 688             }
 689         }
 690         else if ((type != 0x3B) && (type != 00)) /* testing */
 691         {
 692             /* images are OK, but couldn't read to the end of the stream */
 693             return wxGIF_TRUNCATED;
 694         }
 695     }
 696
 697     return wxGIF_OK;
 698 }
 699
 700 #endif // wxUSE_STREAMS && wxUSE_GIF