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