src/common/imaggif.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/imaggif.cpp
   3 // Purpose:     wxGIFHandler
   4 // Author:      Vaclav Slavik, Guillermo Rodriguez Garcia, Gershon Elber, Troels K
   5 // RCS-ID:      $Id$
   6 // Copyright:   (c) 1999-2011 Vaclav Slavik, Guillermo Rodriguez Garcia, Gershon Elber, Troels K
   7 // Licence:     wxWindows licence
   8 /////////////////////////////////////////////////////////////////////////////
   9
  10 // For compilers that support precompilation, includes "wx.h".
  11 #include "wx/wxprec.h"
  12
  13 #ifdef __BORLANDC__
  14     #pragma hdrstop
  15 #endif
  16
  17 #if wxUSE_IMAGE && wxUSE_GIF
  18
  19 #ifndef WX_PRECOMP
  20     #include "wx/intl.h"
  21     #include "wx/log.h"
  22     #include "wx/palette.h"
  23     #include "wx/utils.h"
  24 #endif
  25
  26 #include "wx/imaggif.h"
  27 #include "wx/gifdecod.h"
  28 #include "wx/stream.h"
  29 #include "wx/anidecod.h" // wxImageArray
  30
  31 #define GIF89_HDR     "GIF89a"
  32 #define NETSCAPE_LOOP "NETSCAPE2.0"
  33
  34 // see members.aol.com/royalef/gifabout.htm
  35 //     members.aol.com/royalef/gif89a.txt
  36
  37 enum
  38 {
  39     GIF_MARKER_EXT       = '!', // 0x21
  40     GIF_MARKER_SEP       = ',', // 0x2C
  41     GIF_MARKER_ENDOFDATA = ';', // 0x3B
  42
  43     GIF_MARKER_EXT_GRAPHICS_CONTROL = 0xF9,
  44     GIF_MARKER_EXT_COMMENT          = 0xFE,
  45     GIF_MARKER_EXT_APP              = 0xFF
  46 };
  47
  48 #define LZ_MAX_CODE         4095    // Biggest code possible in 12 bits.
  49 #define FLUSH_OUTPUT        4096    // Impossible code, to signal flush.
  50 #define FIRST_CODE          4097    // Impossible code, to signal first.
  51
  52 #define HT_SIZE         8192        // 12bits = 4096 or twice as big!
  53 #define HT_KEY_MASK     0x1FFF      // 13bits keys
  54
  55 #define HT_GET_KEY(l)   (l >> 12)
  56 #define HT_GET_CODE(l)  (l & 0x0FFF)
  57 #define HT_PUT_KEY(l)   (l << 12)
  58 #define HT_PUT_CODE(l)  (l & 0x0FFF)
  59
  60 struct wxRGB
  61 {
  62     wxUint8 red;
  63     wxUint8 green;
  64     wxUint8 blue;
  65 };
  66
  67 struct GifHashTableType
  68 {
  69     wxUint32 HTable[HT_SIZE];
  70 };
  71
  72 IMPLEMENT_DYNAMIC_CLASS(wxGIFHandler,wxImageHandler)
  73
  74 //----------------------------------------------------------------------------
  75 // Forward declarations
  76 //----------------------------------------------------------------------------
  77
  78 static int wxGIFHandler_KeyItem(unsigned long item);
  79
  80 #if wxUSE_STREAMS
  81
  82 static int wxGIFHandler_BitSize(int n);
  83
  84 #if wxUSE_PALETTE
  85 static bool wxGIFHandler_GetPalette(const wxImage& image,
  86     wxRGB *pal, int *palCount, int *mask_index);
  87 #endif
  88 static
  89 int wxGIFHandler_PaletteFind(const wxRGB& clr, const wxRGB *array, int count);
  90
  91 static bool wxGIFHandler_Write(wxOutputStream *, const void *buf, size_t len);
  92 static bool wxGIFHandler_WriteByte(wxOutputStream *, wxUint8);
  93 static bool wxGIFHandler_WriteWord(wxOutputStream *, wxUint16);
  94 static bool wxGIFHandler_WriteHeader(wxOutputStream *, int width, int height,
  95     bool loop, const wxRGB *pal, int palCount);
  96 static bool wxGIFHandler_WriteRect(wxOutputStream *, int width, int height);
  97 #if wxUSE_PALETTE
  98 static bool wxGIFHandler_WriteTerm(wxOutputStream *);
  99 #endif
 100 static bool wxGIFHandler_WriteZero(wxOutputStream *);
 101 static bool wxGIFHandler_WritePalette(wxOutputStream *,
 102     const wxRGB *pal, size_t palCount, int bpp);
 103 static bool wxGIFHandler_WriteControl(wxOutputStream *,
 104     int maskIndex, int delayMilliSecs);
 105 static bool wxGIFHandler_WriteComment(wxOutputStream *, const wxString&);
 106 static bool wxGIFHandler_WriteLoop(wxOutputStream *);
 107
 108 static bool wxGIFHandler_BufferedOutput(wxOutputStream *, wxUint8 *buf, int c);
 109 #endif // wxUSE_STREAMS
 110
 111 //-----------------------------------------------------------------------------
 112 // wxGIFHandler
 113 //-----------------------------------------------------------------------------
 114
 115 #if wxUSE_STREAMS
 116
 117 bool wxGIFHandler::LoadFile(wxImage *image, wxInputStream& stream,
 118     bool verbose, int index)
 119 {
 120     wxGIFDecoder *decod;
 121     wxGIFErrorCode error;
 122     bool ok = true;
 123
 124 //    image->Destroy();
 125     decod = new wxGIFDecoder();
 126     error = decod->LoadGIF(stream);
 127
 128     if ((error != wxGIF_OK) && (error != wxGIF_TRUNCATED))
 129     {
 130         if (verbose)
 131         {
 132             switch (error)
 133             {
 134                 case wxGIF_INVFORMAT:
 135                     wxLogError(_("GIF: error in GIF image format."));
 136                     break;
 137                 case wxGIF_MEMERR:
 138                     wxLogError(_("GIF: not enough memory."));
 139                     break;
 140                 default:
 141                     wxLogError(_("GIF: unknown error!!!"));
 142                     break;
 143             }
 144         }
 145         delete decod;
 146         return false;
 147     }
 148
 149     if ((error == wxGIF_TRUNCATED) && verbose)
 150     {
 151         wxLogError(_("GIF: data stream seems to be truncated."));
 152         // go on; image data is OK
 153     }
 154
 155     if (ok)
 156     {
 157         ok = decod->ConvertToImage(index != -1 ? (size_t)index : 0, image);
 158     }
 159     else
 160     {
 161         wxLogError(_("GIF: Invalid gif index."));
 162     }
 163
 164     delete decod;
 165
 166     return ok;
 167 }
 168
 169 bool wxGIFHandler::SaveFile(wxImage *image,
 170     wxOutputStream& stream, bool verbose)
 171 {
 172 #if wxUSE_PALETTE
 173     wxRGB pal[256];
 174     int palCount;
 175     int maskIndex;
 176
 177     return wxGIFHandler_GetPalette(*image, pal, &palCount, &maskIndex)
 178         && DoSaveFile(*image, &stream, verbose, true /*first?*/, 0,
 179             false /*loop?*/, pal, palCount, maskIndex)
 180         && wxGIFHandler_WriteTerm(&stream);
 181 #else
 182     wxUnusedVar(image);
 183     wxUnusedVar(stream);
 184     wxUnusedVar(verbose);
 185     return false;
 186 #endif
 187 }
 188
 189 bool wxGIFHandler::DoCanRead( wxInputStream& stream )
 190 {
 191     wxGIFDecoder decod;
 192     return decod.CanRead(stream);
 193          // it's ok to modify the stream position here
 194 }
 195
 196 int wxGIFHandler::DoGetImageCount( wxInputStream& stream )
 197 {
 198     wxGIFDecoder decod;
 199     wxGIFErrorCode error = decod.LoadGIF(stream);
 200     if ( (error != wxGIF_OK) && (error != wxGIF_TRUNCATED) )
 201         return -1;
 202
 203     // NOTE: this function modifies the current stream position but it's ok
 204     //       (see wxImageHandler::GetImageCount)
 205
 206     return decod.GetFrameCount();
 207 }
 208
 209 bool wxGIFHandler::DoSaveFile(const wxImage& image, wxOutputStream *stream,
 210     bool WXUNUSED(verbose), bool first, int delayMilliSecs, bool loop,
 211     const wxRGB *pal, int palCount, int maskIndex)
 212 {
 213     const unsigned long colorcount = image.CountColours(256+1);
 214     bool ok = colorcount && (colorcount <= 256);
 215     if (!ok)
 216     {
 217         return false;
 218     }
 219
 220     int width = image.GetWidth();
 221     int height = image.GetHeight();
 222     int width_even = width + ((width % 2) ? 1 : 0);
 223
 224     if (first)
 225     {
 226         ok = wxGIFHandler_WriteHeader(stream, width, height, loop,
 227             pal, palCount);
 228     }
 229
 230     ok = ok
 231         && wxGIFHandler_WriteComment(stream,
 232             image.GetOption(wxIMAGE_OPTION_GIF_COMMENT))
 233         && wxGIFHandler_WriteControl(stream, maskIndex, delayMilliSecs)
 234         && wxGIFHandler_WriteByte(stream, GIF_MARKER_SEP)
 235         && wxGIFHandler_WriteRect(stream, width, height);
 236
 237     // local palette
 238     if (first)
 239     {
 240         // we already saved the (global) palette
 241         ok = ok && wxGIFHandler_WriteZero(stream);
 242     }
 243     else
 244     {
 245         const int bpp = wxGIFHandler_BitSize(palCount);
 246         wxUint8 b;
 247
 248         b = 0x80;
 249         b |=(bpp - 1) << 5;
 250         b |=(bpp - 1);
 251         b &=~0x40; // clear interlaced
 252
 253         ok = ok && wxGIFHandler_WriteByte(stream, b)
 254             && wxGIFHandler_WritePalette(stream, pal, palCount, bpp);
 255     }
 256
 257     if (!ok)
 258     {
 259         return false;
 260     }
 261
 262     if (!InitHashTable())
 263     {
 264         wxLogError(_("Couldn't initialize GIF hash table."));
 265         return false;
 266     }
 267
 268     const wxUint8 *src = image.GetData();
 269     wxUint8 *eightBitData = new wxUint8[width];
 270
 271     SetupCompress(stream, 8);
 272
 273     m_pixelCount = height * width_even;
 274     for (int y = 0; y < height; y++)
 275     {
 276         m_pixelCount -= width_even;
 277         for (int x = 0; x < width; x++)
 278         {
 279             wxRGB rgb;
 280             rgb.red   = src[0];
 281             rgb.green = src[1];
 282             rgb.blue  = src[2];
 283             int index = wxGIFHandler_PaletteFind(rgb, pal, palCount);
 284             wxASSERT(index != wxNOT_FOUND);
 285             eightBitData[x] = (wxUint8)index;
 286             src+=3;
 287         }
 288
 289         ok = CompressLine(stream, eightBitData, width);
 290         if (!ok)
 291         {
 292             break;
 293         }
 294     }
 295
 296     delete [] eightBitData;
 297
 298     wxDELETE(m_hashTable);
 299
 300     return ok;
 301 }
 302
 303 bool wxGIFHandler::SaveAnimation(const wxImageArray& images,
 304     wxOutputStream *stream, bool verbose, int delayMilliSecs)
 305 {
 306 #if wxUSE_PALETTE
 307     bool ok = true;
 308     size_t i;
 309
 310     wxSize size(0,0);
 311     for (i = 0; (i < images.GetCount()) && ok; i++)
 312     {
 313         const wxImage& image = images.Item(i);
 314         wxSize temp(image.GetWidth(), image.GetHeight());
 315         ok = ok && image.HasPalette();
 316         if (i)
 317         {
 318            ok = ok && (size == temp);
 319         }
 320         else
 321         {
 322            size = temp;
 323         }
 324     }
 325
 326     for (i = 0; (i < images.GetCount()) && ok; i++)
 327     {
 328         const wxImage& image = images.Item(i);
 329
 330         wxRGB pal[256];
 331         int palCount;
 332         int maskIndex;
 333
 334         ok = wxGIFHandler_GetPalette(image, pal, &palCount, &maskIndex)
 335           && DoSaveFile(image, stream, verbose, i == 0 /*first?*/, delayMilliSecs,
 336             true /*loop?*/, pal, palCount, maskIndex);
 337     }
 338
 339     return ok && wxGIFHandler_WriteTerm(stream);
 340 #else
 341     wxUnusedVar(images);
 342     wxUnusedVar(stream);
 343     wxUnusedVar(verbose);
 344     wxUnusedVar(delayMilliSecs);
 345
 346     return false;
 347 #endif
 348 }
 349
 350 bool wxGIFHandler::CompressOutput(wxOutputStream *stream, int code)
 351 {
 352     if (code == FLUSH_OUTPUT)
 353     {
 354         while (m_crntShiftState > 0)
 355         {
 356             // Get rid of what is left in DWord, and flush it.
 357             if (!wxGIFHandler_BufferedOutput(stream, m_LZBuf,
 358                 m_crntShiftDWord & 0xff))
 359             {
 360                 return false;
 361             }
 362             m_crntShiftDWord >>= 8;
 363             m_crntShiftState -= 8;
 364         }
 365         m_crntShiftState = 0;                       // For next time.
 366         if (!wxGIFHandler_BufferedOutput(stream, m_LZBuf, FLUSH_OUTPUT))
 367         {
 368             return false;
 369         }
 370     }
 371     else
 372     {
 373         m_crntShiftDWord |= ((long) code) << m_crntShiftState;
 374         m_crntShiftState += m_runningBits;
 375         while (m_crntShiftState >= 8)
 376         {
 377             // Dump out full bytes:
 378             if (!wxGIFHandler_BufferedOutput(stream, m_LZBuf,
 379                 m_crntShiftDWord & 0xff))
 380             {
 381                 return false;
 382             }
 383             m_crntShiftDWord >>= 8;
 384             m_crntShiftState -= 8;
 385         }
 386     }
 387
 388     // If code can't fit into RunningBits bits, must raise its size. Note
 389     // however that codes above LZ_MAX_CODE are used for special signaling.
 390     if ( (m_runningCode >= m_maxCode1) && (code <= LZ_MAX_CODE))
 391     {
 392         m_maxCode1 = 1 << ++m_runningBits;
 393     }
 394     return true;
 395 }
 396
 397 bool wxGIFHandler::SetupCompress(wxOutputStream *stream, int bpp)
 398 {
 399     m_LZBuf[0] = 0;           // Nothing was output yet.
 400     m_clearCode = (1 << bpp);
 401     m_EOFCode = m_clearCode + 1;
 402     m_runningCode = m_EOFCode + 1;
 403     m_runningBits = bpp + 1;     // Number of bits per code.
 404     m_maxCode1 = 1 << m_runningBits;       // Max. code + 1.
 405     m_crntCode = FIRST_CODE;       // Signal that this is first one!
 406     m_crntShiftState = 0;      // No information in CrntShiftDWord.
 407     m_crntShiftDWord = 0;
 408
 409     // Clear hash table and send Clear to make sure the decoder does the same.
 410     ClearHashTable();
 411
 412     return wxGIFHandler_WriteByte(stream, (wxUint8)bpp)
 413         && CompressOutput(stream, m_clearCode);
 414 }
 415
 416 bool wxGIFHandler::CompressLine(wxOutputStream *stream,
 417     const wxUint8 *line, int lineLen)
 418 {
 419     int i = 0, crntCode, newCode;
 420     unsigned long newKey;
 421     wxUint8 pixel;
 422     if (m_crntCode == FIRST_CODE)                  // It's first time!
 423         crntCode = line[i++];
 424     else
 425         crntCode = m_crntCode;     // Get last code in compression.
 426
 427     while (i < lineLen)
 428     {
 429         // Decode lineLen items.
 430         pixel = line[i++];                    // Get next pixel from stream.
 431         // Form a new unique key to search hash table for the code combines
 432         // crntCode as Prefix string with Pixel as postfix char.
 433         newKey = (((unsigned long) crntCode) << 8) + pixel;
 434         if ((newCode = ExistsHashTable(newKey)) >= 0)
 435         {
 436             // This Key is already there, or the string is old one, so
 437             // simply take new code as our crntCode:
 438             crntCode = newCode;
 439         }
 440         else
 441         {
 442             // Put it in hash table, output the prefix code, and make our
 443             // crntCode equal to Pixel.
 444             if (!CompressOutput(stream, crntCode))
 445             {
 446                 return false;
 447             }
 448
 449             crntCode = pixel;
 450
 451             // If however the HashTable is full, we send a clear first and
 452             // Clear the hash table.
 453             if (m_runningCode >= LZ_MAX_CODE)
 454             {
 455                 // Time to do some clearance:
 456                 if (!CompressOutput(stream, m_clearCode))
 457                 {
 458                     return false;
 459                 }
 460
 461                 m_runningCode = m_EOFCode + 1;
 462                 m_runningBits = 8 + 1;
 463                 m_maxCode1 = 1 << m_runningBits;
 464                 ClearHashTable();
 465             }
 466             else
 467             {
 468                 // Put this unique key with its relative Code in hash table:
 469                 InsertHashTable(newKey, m_runningCode++);
 470             }
 471         }
 472     }
 473     // Preserve the current state of the compression algorithm:
 474     m_crntCode = crntCode;
 475     if (m_pixelCount == 0)
 476     {
 477         // We are done - output last Code and flush output buffers:
 478         if (!CompressOutput(stream, crntCode)
 479             || !CompressOutput(stream, m_EOFCode)
 480             || !CompressOutput(stream, FLUSH_OUTPUT))
 481         {
 482             return false;
 483         }
 484     }
 485
 486     return true;
 487 }
 488
 489 #endif  // wxUSE_STREAMS
 490
 491 bool wxGIFHandler::InitHashTable()
 492 {
 493     if (!m_hashTable)
 494     {
 495         m_hashTable = new GifHashTableType();
 496     }
 497
 498     if (!m_hashTable)
 499     {
 500         return false;
 501     }
 502
 503     ClearHashTable();
 504
 505     return true;
 506 }
 507
 508 void wxGIFHandler::ClearHashTable()
 509 {
 510     int index = HT_SIZE;
 511     wxUint32 *HTable = m_hashTable->HTable;
 512
 513     while (--index>=0)
 514     {
 515         HTable[index] = 0xfffffffful;
 516     }
 517 }
 518
 519 void wxGIFHandler::InsertHashTable(unsigned long key, int code)
 520 {
 521     int hKey = wxGIFHandler_KeyItem(key);
 522     wxUint32 *HTable = m_hashTable->HTable;
 523
 524     while (HT_GET_KEY(HTable[hKey]) != 0xFFFFFL)
 525     {
 526         hKey = (hKey + 1) & HT_KEY_MASK;
 527     }
 528     HTable[hKey] = HT_PUT_KEY(key) | HT_PUT_CODE(code);
 529 }
 530
 531
 532 int wxGIFHandler::ExistsHashTable(unsigned long key)
 533 {
 534     int hKey = wxGIFHandler_KeyItem(key);
 535     wxUint32 *HTable = m_hashTable->HTable, HTKey;
 536
 537     while ((HTKey = HT_GET_KEY(HTable[hKey])) != 0xFFFFFL)
 538     {
 539         if (key == HTKey)
 540         {
 541             return HT_GET_CODE(HTable[hKey]);
 542         }
 543         hKey = (hKey + 1) & HT_KEY_MASK;
 544     }
 545     return -1;
 546 }
 547
 548 // ---------------------------------------------------------------------------
 549 // implementation of global private functions
 550 // ---------------------------------------------------------------------------
 551
 552 int wxGIFHandler_KeyItem(unsigned long item)
 553 {
 554     return ((item >> 12) ^ item) & HT_KEY_MASK;
 555 }
 556
 557 #if wxUSE_STREAMS
 558
 559 int wxGIFHandler_BitSize(int n)
 560 {
 561     int i;
 562     for (i = 1; i <= 8; i++)
 563     {
 564         if ((1 << i) >= n)
 565         {
 566             break;
 567         }
 568     }
 569     return i;
 570 }
 571
 572 #if wxUSE_PALETTE
 573 bool wxGIFHandler_GetPalette(const wxImage& image,
 574     wxRGB *pal, int *pPalCount, int *pMaskIndex)
 575 {
 576     if (!image.HasPalette())
 577     {
 578         return false;
 579     }
 580
 581     const wxPalette& palette = image.GetPalette();
 582     int palCount = palette.GetColoursCount();
 583
 584     for (int i = 0; i < palCount; ++i)
 585     {
 586         if (!palette.GetRGB(i, &pal[i].red, &pal[i].green, &pal[i].blue))
 587         {
 588             break;
 589         }
 590     }
 591     if (image.HasMask())
 592     {
 593         wxRGB mask;
 594
 595         mask.red   = image.GetMaskRed();
 596         mask.green = image.GetMaskGreen();
 597         mask.blue  = image.GetMaskBlue();
 598         *pMaskIndex = wxGIFHandler_PaletteFind(mask, pal, palCount);
 599         if ( (*pMaskIndex == wxNOT_FOUND) && (palCount < 256))
 600         {
 601             *pMaskIndex = palCount;
 602             pal[palCount++] = mask;
 603         }
 604     }
 605     else
 606     {
 607         *pMaskIndex = wxNOT_FOUND;
 608     }
 609     *pPalCount = palCount;
 610
 611     return true;
 612 }
 613 #endif // wxUSE_PALETTE
 614
 615 int wxGIFHandler_PaletteFind(const wxRGB& clr, const wxRGB *array, int count)
 616 {
 617     for (int i = 0; i < count; i++)
 618     {
 619         if (   (clr.red   == array[i].red)
 620             && (clr.green == array[i].green)
 621             && (clr.blue  == array[i].blue))
 622         {
 623             return i;
 624         }
 625     }
 626
 627     return wxNOT_FOUND;
 628 }
 629
 630 bool wxGIFHandler_Write(wxOutputStream *stream, const void *buf, size_t len)
 631 {
 632     return (len == stream->Write(buf, len).LastWrite());
 633 }
 634
 635 bool wxGIFHandler_WriteByte(wxOutputStream *stream, wxUint8 byte)
 636 {
 637     return wxGIFHandler_Write(stream, &byte, sizeof(byte));
 638 }
 639
 640 bool wxGIFHandler_WriteWord(wxOutputStream *stream, wxUint16 word)
 641 {
 642     wxUint8 buf[2];
 643
 644     buf[0] = word & 0xff;
 645     buf[1] = (word >> 8) & 0xff;
 646     return wxGIFHandler_Write(stream, &word, sizeof(word));
 647 }
 648
 649 bool wxGIFHandler_WriteHeader(wxOutputStream *stream, int width, int height,
 650     bool loop, const wxRGB *pal, int palCount)
 651 {
 652     const int bpp = wxGIFHandler_BitSize(palCount);
 653     wxUint8 buf[3];
 654
 655     bool ok = wxGIFHandler_Write(stream, GIF89_HDR, sizeof(GIF89_HDR)-1)
 656         && wxGIFHandler_WriteWord(stream, (wxUint16) width)
 657         && wxGIFHandler_WriteWord(stream, (wxUint16) height);
 658
 659     buf[0] = 0x80;
 660     buf[0] |=(bpp - 1) << 5;
 661     buf[0] |=(bpp - 1);
 662     buf[1] = 0; // background color == entry 0
 663     buf[2] = 0; // aspect ratio 1:1
 664     ok = ok && wxGIFHandler_Write(stream, buf, sizeof(buf))
 665         && wxGIFHandler_WritePalette(stream, pal, palCount, bpp);
 666
 667     if (loop)
 668     {
 669        ok = ok && wxGIFHandler_WriteLoop(stream);
 670     }
 671
 672     return ok;
 673 }
 674
 675 bool wxGIFHandler_WriteRect(wxOutputStream *stream, int width, int height)
 676 {
 677     return wxGIFHandler_WriteWord(stream, 0) // left
 678         && wxGIFHandler_WriteWord(stream, 0) // top
 679         && wxGIFHandler_WriteWord(stream, (wxUint16) width)
 680         && wxGIFHandler_WriteWord(stream, (wxUint16) height);
 681 }
 682
 683 #if wxUSE_PALETTE
 684 bool wxGIFHandler_WriteTerm(wxOutputStream *stream)
 685 {
 686     return wxGIFHandler_WriteByte(stream, GIF_MARKER_ENDOFDATA);
 687 }
 688 #endif
 689
 690 bool wxGIFHandler_WriteZero(wxOutputStream *stream)
 691 {
 692     return wxGIFHandler_WriteByte(stream, 0);
 693 }
 694
 695 bool wxGIFHandler_WritePalette(wxOutputStream *stream,
 696     const wxRGB *array, size_t count, int bpp)
 697 {
 698     wxUint8 buf[3];
 699     for (int i = 0; (i < (1 << bpp)); i++)
 700     {
 701         if (i < (int)count)
 702         {
 703             buf[0] = array[i].red;
 704             buf[1] = array[i].green;
 705             buf[2] = array[i].blue;
 706         }
 707         else
 708         {
 709             buf[0] = buf[1] = buf[2] = 0;
 710         }
 711
 712         if ( !wxGIFHandler_Write(stream, buf, sizeof(buf)) )
 713         {
 714             return false;
 715         }
 716     }
 717
 718     return true;
 719 }
 720
 721 bool wxGIFHandler_WriteControl(wxOutputStream *stream,
 722     int maskIndex, int delayMilliSecs)
 723 {
 724     wxUint8 buf[8];
 725
 726     buf[0] = GIF_MARKER_EXT;    // extension marker
 727     buf[1] = GIF_MARKER_EXT_GRAPHICS_CONTROL;
 728     buf[2] = 4;     // length of block
 729     buf[3] = (maskIndex != wxNOT_FOUND) ? 1 : 0;   // has transparency
 730     buf[4] = delayMilliSecs / 10; // delay time
 731     buf[5] = 0;
 732     buf[6] = (maskIndex != wxNOT_FOUND) ? (wxUint8) maskIndex : 0;
 733     buf[7] = 0;
 734     return wxGIFHandler_Write(stream, buf, sizeof(buf));
 735 }
 736
 737 bool wxGIFHandler_WriteComment(wxOutputStream *stream, const wxString& comment)
 738 {
 739     if ( comment.empty() )
 740     {
 741         return true;
 742     }
 743
 744     // Write comment header.
 745     wxUint8 buf[2];
 746     buf[0] = GIF_MARKER_EXT;
 747     buf[1] = GIF_MARKER_EXT_COMMENT;
 748     if ( !wxGIFHandler_Write(stream, buf, sizeof(buf)) )
 749     {
 750         return false;
 751     }
 752
 753     /*
 754     If comment is longer than 255 bytes write it in blocks of maximum 255
 755     bytes each.
 756     */
 757     wxCharBuffer text( comment.mb_str() );
 758
 759     size_t pos = 0, fullLength = text.length();
 760
 761     do
 762     {
 763         size_t blockLength = wxMin(fullLength - pos, 255);
 764
 765         if ( !wxGIFHandler_WriteByte(stream, (wxUint8) blockLength)
 766             || !wxGIFHandler_Write(stream, &text.data()[pos], blockLength) )
 767         {
 768             return false;
 769         }
 770
 771         pos += blockLength;
 772     }while (pos < fullLength);
 773
 774
 775     // Write comment footer.
 776     return wxGIFHandler_WriteZero(stream);
 777 }
 778
 779 bool wxGIFHandler_WriteLoop(wxOutputStream *stream)
 780 {
 781     wxUint8 buf[4];
 782     const int loopcount = 0; // infinite
 783
 784     buf[0] = GIF_MARKER_EXT;
 785     buf[1] = GIF_MARKER_EXT_APP;
 786     buf[2] = 0x0B;
 787     bool ok = wxGIFHandler_Write(stream, buf, 3)
 788         && wxGIFHandler_Write(stream, NETSCAPE_LOOP, sizeof(NETSCAPE_LOOP)-1);
 789
 790     buf[0] = 3;
 791     buf[1] = 1;
 792     buf[2] = loopcount & 0xFF;
 793     buf[3] = loopcount >> 8;
 794
 795     return ok && wxGIFHandler_Write(stream, buf, 4)
 796         && wxGIFHandler_WriteZero(stream);
 797 }
 798
 799 bool wxGIFHandler_BufferedOutput(wxOutputStream *stream, wxUint8 *buf, int c)
 800 {
 801     bool ok = true;
 802
 803     if (c == FLUSH_OUTPUT)
 804     {
 805         // Flush everything out.
 806         if (buf[0])
 807         {
 808             ok = wxGIFHandler_Write(stream, buf, buf[0]+1);
 809         }
 810         // Mark end of compressed data, by an empty block (see GIF doc):
 811         wxGIFHandler_WriteZero(stream);
 812     }
 813     else
 814     {
 815         if (buf[0] == 255)
 816         {
 817             // Dump out this buffer - it is full:
 818             ok = wxGIFHandler_Write(stream, buf, buf[0] + 1);
 819             buf[0] = 0;
 820         }
 821         buf[++buf[0]] = c;
 822     }
 823
 824     return ok;
 825 }
 826
 827 #endif // wxUSE_STREAMS
 828
 829 #endif  // wxUSE_IMAGE && wxUSE_GIF