src/common/imagtiff.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/imagtiff.cpp
   3 // Purpose:     wxImage TIFF handler
   4 // Author:      Robert Roebling
   5 // RCS-ID:      $Id$
   6 // Copyright:   (c) Robert Roebling
   7 // Licence:     wxWindows licence
   8 /////////////////////////////////////////////////////////////////////////////
   9
  10 // ============================================================================
  11 // declarations
  12 // ============================================================================
  13
  14 // ----------------------------------------------------------------------------
  15 // headers
  16 // ----------------------------------------------------------------------------
  17
  18 // For compilers that support precompilation, includes "wx.h".
  19 #include "wx/wxprec.h"
  20
  21 #ifdef __BORLANDC__
  22     #pragma hdrstop
  23 #endif
  24
  25 #if wxUSE_IMAGE && wxUSE_LIBTIFF
  26
  27 #include "wx/imagtiff.h"
  28 #include "wx/versioninfo.h"
  29
  30 #ifndef WX_PRECOMP
  31     #include "wx/log.h"
  32     #include "wx/app.h"
  33     #include "wx/intl.h"
  34     #include "wx/bitmap.h"
  35     #include "wx/module.h"
  36     #include "wx/wxcrtvararg.h"
  37 #endif
  38
  39 extern "C"
  40 {
  41 #ifdef __DMC__
  42     #include "tif_config.h"
  43 #endif
  44     #include "tiff.h"
  45     #include "tiffio.h"
  46 }
  47 #include "wx/filefn.h"
  48 #include "wx/wfstream.h"
  49
  50 #ifndef TIFFLINKAGEMODE
  51     #if defined(__WATCOMC__) && defined(__WXMGL__)
  52         #define TIFFLINKAGEMODE cdecl
  53     #else
  54         #define TIFFLINKAGEMODE LINKAGEMODE
  55     #endif
  56 #endif
  57
  58 // ============================================================================
  59 // implementation
  60 // ============================================================================
  61
  62 // ----------------------------------------------------------------------------
  63 // TIFF library error/warning handlers
  64 // ----------------------------------------------------------------------------
  65
  66 static wxString
  67 FormatTiffMessage(const char *module, const char *fmt, va_list ap)
  68 {
  69     char buf[512];
  70     if ( wxCRT_VsnprintfA(buf, WXSIZEOF(buf), fmt, ap) <= 0 )
  71     {
  72         // this isn't supposed to happen, but if it does, it's better
  73         // than nothing
  74         strcpy(buf, "Incorrectly formatted TIFF message");
  75     }
  76     buf[WXSIZEOF(buf)-1] = 0; // make sure it is always NULL-terminated
  77
  78     wxString msg(buf);
  79     if ( module )
  80         msg += wxString::Format(_(" (in module \"%s\")"), module);
  81
  82     return msg;
  83 }
  84
  85 extern "C"
  86 {
  87
  88 static void
  89 TIFFwxWarningHandler(const char* module, const char *fmt, va_list ap)
  90 {
  91     wxLogWarning("%s", FormatTiffMessage(module, fmt, ap));
  92 }
  93
  94 static void
  95 TIFFwxErrorHandler(const char* module, const char *fmt, va_list ap)
  96 {
  97     wxLogError("%s", FormatTiffMessage(module, fmt, ap));
  98 }
  99
 100 } // extern "C"
 101
 102 //-----------------------------------------------------------------------------
 103 // wxTIFFHandler
 104 //-----------------------------------------------------------------------------
 105
 106 IMPLEMENT_DYNAMIC_CLASS(wxTIFFHandler,wxImageHandler)
 107
 108 wxTIFFHandler::wxTIFFHandler()
 109 {
 110     m_name = wxT("TIFF file");
 111     m_extension = wxT("tif");
 112     m_altExtensions.Add(wxT("tiff"));
 113     m_type = wxBITMAP_TYPE_TIFF;
 114     m_mime = wxT("image/tiff");
 115     TIFFSetWarningHandler((TIFFErrorHandler) TIFFwxWarningHandler);
 116     TIFFSetErrorHandler((TIFFErrorHandler) TIFFwxErrorHandler);
 117 }
 118
 119 #if wxUSE_STREAMS
 120
 121 // helper to translate our, possibly 64 bit, wxFileOffset to TIFF, always 32
 122 // bit, toff_t
 123 static toff_t wxFileOffsetToTIFF(wxFileOffset ofs)
 124 {
 125     if ( ofs == wxInvalidOffset )
 126         return (toff_t)-1;
 127
 128     toff_t tofs = wx_truncate_cast(toff_t, ofs);
 129     wxCHECK_MSG( (wxFileOffset)tofs == ofs, (toff_t)-1,
 130                     wxT("TIFF library doesn't support large files") );
 131
 132     return tofs;
 133 }
 134
 135 // another helper to convert standard seek mode to our
 136 static wxSeekMode wxSeekModeFromTIFF(int whence)
 137 {
 138     switch ( whence )
 139     {
 140         case SEEK_SET:
 141             return wxFromStart;
 142
 143         case SEEK_CUR:
 144             return wxFromCurrent;
 145
 146         case SEEK_END:
 147             return wxFromEnd;
 148
 149         default:
 150             return wxFromCurrent;
 151     }
 152 }
 153
 154 extern "C"
 155 {
 156
 157 tsize_t TIFFLINKAGEMODE
 158 wxTIFFNullProc(thandle_t WXUNUSED(handle),
 159           tdata_t WXUNUSED(buf),
 160           tsize_t WXUNUSED(size))
 161 {
 162     return (tsize_t) -1;
 163 }
 164
 165 tsize_t TIFFLINKAGEMODE
 166 wxTIFFReadProc(thandle_t handle, tdata_t buf, tsize_t size)
 167 {
 168     wxInputStream *stream = (wxInputStream*) handle;
 169     stream->Read( (void*) buf, (size_t) size );
 170     return wx_truncate_cast(tsize_t, stream->LastRead());
 171 }
 172
 173 tsize_t TIFFLINKAGEMODE
 174 wxTIFFWriteProc(thandle_t handle, tdata_t buf, tsize_t size)
 175 {
 176     wxOutputStream *stream = (wxOutputStream*) handle;
 177     stream->Write( (void*) buf, (size_t) size );
 178     return wx_truncate_cast(tsize_t, stream->LastWrite());
 179 }
 180
 181 toff_t TIFFLINKAGEMODE
 182 wxTIFFSeekIProc(thandle_t handle, toff_t off, int whence)
 183 {
 184     wxInputStream *stream = (wxInputStream*) handle;
 185
 186     return wxFileOffsetToTIFF(stream->SeekI((wxFileOffset)off,
 187                                             wxSeekModeFromTIFF(whence)));
 188 }
 189
 190 toff_t TIFFLINKAGEMODE
 191 wxTIFFSeekOProc(thandle_t handle, toff_t off, int whence)
 192 {
 193     wxOutputStream *stream = (wxOutputStream*) handle;
 194
 195     toff_t offset = wxFileOffsetToTIFF(
 196         stream->SeekO((wxFileOffset)off, wxSeekModeFromTIFF(whence)) );
 197
 198     if (offset != (toff_t) -1 || whence != SEEK_SET)
 199     {
 200         return offset;
 201     }
 202
 203
 204     /*
 205     Try to workaround problems with libtiff seeking past the end of streams.
 206
 207     This occurs when libtiff is writing tag entries past the end of a
 208     stream but hasn't written the directory yet (which will be placed
 209     before the tags and contain offsets to the just written tags).
 210     The behaviour for seeking past the end of a stream is not consistent
 211     and doesn't work with for example wxMemoryOutputStream. When this type
 212     of seeking fails (with SEEK_SET), fill in the gap with zeroes and try
 213     again.
 214     */
 215
 216     wxFileOffset streamLength = stream->GetLength();
 217     if (streamLength != wxInvalidOffset && (wxFileOffset) off > streamLength)
 218     {
 219        if (stream->SeekO(streamLength, wxFromStart) == wxInvalidOffset)
 220        {
 221            return (toff_t) -1;
 222        }
 223
 224        for (wxFileOffset i = 0; i < (wxFileOffset) off - streamLength; ++i)
 225        {
 226            stream->PutC(0);
 227        }
 228     }
 229
 230     return wxFileOffsetToTIFF( stream->TellO() );
 231 }
 232
 233 int TIFFLINKAGEMODE
 234 wxTIFFCloseIProc(thandle_t WXUNUSED(handle))
 235 {
 236     // there is no need to close the input stream
 237     return 0;
 238 }
 239
 240 int TIFFLINKAGEMODE
 241 wxTIFFCloseOProc(thandle_t handle)
 242 {
 243     wxOutputStream *stream = (wxOutputStream*) handle;
 244
 245     return stream->Close() ? 0 : -1;
 246 }
 247
 248 toff_t TIFFLINKAGEMODE
 249 wxTIFFSizeProc(thandle_t handle)
 250 {
 251     wxStreamBase *stream = (wxStreamBase*) handle;
 252     return (toff_t) stream->GetSize();
 253 }
 254
 255 int TIFFLINKAGEMODE
 256 wxTIFFMapProc(thandle_t WXUNUSED(handle),
 257              tdata_t* WXUNUSED(pbase),
 258              toff_t* WXUNUSED(psize))
 259 {
 260     return 0;
 261 }
 262
 263 void TIFFLINKAGEMODE
 264 wxTIFFUnmapProc(thandle_t WXUNUSED(handle),
 265                tdata_t WXUNUSED(base),
 266                toff_t WXUNUSED(size))
 267 {
 268 }
 269
 270 } // extern "C"
 271
 272 TIFF*
 273 TIFFwxOpen(wxInputStream &stream, const char* name, const char* mode)
 274 {
 275     TIFF* tif = TIFFClientOpen(name, mode,
 276         (thandle_t) &stream,
 277         wxTIFFReadProc, wxTIFFNullProc,
 278         wxTIFFSeekIProc, wxTIFFCloseIProc, wxTIFFSizeProc,
 279         wxTIFFMapProc, wxTIFFUnmapProc);
 280
 281     return tif;
 282 }
 283
 284 TIFF*
 285 TIFFwxOpen(wxOutputStream &stream, const char* name, const char* mode)
 286 {
 287     TIFF* tif = TIFFClientOpen(name, mode,
 288         (thandle_t) &stream,
 289         wxTIFFNullProc, wxTIFFWriteProc,
 290         wxTIFFSeekOProc, wxTIFFCloseOProc, wxTIFFSizeProc,
 291         wxTIFFMapProc, wxTIFFUnmapProc);
 292
 293     return tif;
 294 }
 295
 296 bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose, int index )
 297 {
 298     if (index == -1)
 299         index = 0;
 300
 301     image->Destroy();
 302
 303     TIFF *tif = TIFFwxOpen( stream, "image", "r" );
 304
 305     if (!tif)
 306     {
 307         if (verbose)
 308         {
 309             wxLogError( _("TIFF: Error loading image.") );
 310         }
 311
 312         return false;
 313     }
 314
 315     if (!TIFFSetDirectory( tif, (tdir_t)index ))
 316     {
 317         if (verbose)
 318         {
 319             wxLogError( _("Invalid TIFF image index.") );
 320         }
 321
 322         TIFFClose( tif );
 323
 324         return false;
 325     }
 326
 327     uint32 w, h;
 328     uint32 *raster;
 329
 330     TIFFGetField( tif, TIFFTAG_IMAGEWIDTH, &w );
 331     TIFFGetField( tif, TIFFTAG_IMAGELENGTH, &h );
 332
 333     uint16 samplesPerPixel = 0;
 334     (void) TIFFGetFieldDefaulted(tif, TIFFTAG_SAMPLESPERPIXEL, &samplesPerPixel);
 335
 336     uint16 bitsPerSample = 0;
 337     (void) TIFFGetFieldDefaulted(tif, TIFFTAG_BITSPERSAMPLE, &bitsPerSample);
 338
 339     uint16 extraSamples;
 340     uint16* samplesInfo;
 341     TIFFGetFieldDefaulted(tif, TIFFTAG_EXTRASAMPLES,
 342                           &extraSamples, &samplesInfo);
 343
 344     uint16 photometric;
 345     if (!TIFFGetField(tif, TIFFTAG_PHOTOMETRIC, &photometric))
 346     {
 347         photometric = PHOTOMETRIC_MINISWHITE;
 348     }
 349     const bool hasAlpha = (extraSamples >= 1
 350         && ((samplesInfo[0] == EXTRASAMPLE_UNSPECIFIED)
 351             || samplesInfo[0] == EXTRASAMPLE_ASSOCALPHA
 352             || samplesInfo[0] == EXTRASAMPLE_UNASSALPHA))
 353         || (extraSamples == 0 && samplesPerPixel == 4
 354             && photometric == PHOTOMETRIC_RGB);
 355
 356     // guard against integer overflow during multiplication which could result
 357     // in allocating a too small buffer and then overflowing it
 358     const double bytesNeeded = (double)w * (double)h * sizeof(uint32);
 359     if ( bytesNeeded >= wxUINT32_MAX )
 360     {
 361         if ( verbose )
 362         {
 363             wxLogError( _("TIFF: Image size is abnormally big.") );
 364         }
 365
 366         TIFFClose(tif);
 367
 368         return false;
 369     }
 370
 371     raster = (uint32*) _TIFFmalloc( (uint32)bytesNeeded );
 372
 373     if (!raster)
 374     {
 375         if (verbose)
 376         {
 377             wxLogError( _("TIFF: Couldn't allocate memory.") );
 378         }
 379
 380         TIFFClose( tif );
 381
 382         return false;
 383     }
 384
 385     image->Create( (int)w, (int)h );
 386     if (!image->IsOk())
 387     {
 388         if (verbose)
 389         {
 390             wxLogError( _("TIFF: Couldn't allocate memory.") );
 391         }
 392
 393         _TIFFfree( raster );
 394         TIFFClose( tif );
 395
 396         return false;
 397     }
 398
 399     if ( hasAlpha )
 400         image->SetAlpha();
 401
 402     uint16 planarConfig = PLANARCONFIG_CONTIG;
 403     (void) TIFFGetField(tif, TIFFTAG_PLANARCONFIG, &planarConfig);
 404
 405     bool ok = true;
 406     char msg[1024] = "";
 407     if
 408     (
 409         (planarConfig == PLANARCONFIG_CONTIG && samplesPerPixel == 2
 410             && extraSamples == 1)
 411         &&
 412         (
 413             ( !TIFFRGBAImageOK(tif, msg) )
 414             || (bitsPerSample == 8)
 415         )
 416     )
 417     {
 418         const bool isGreyScale = (bitsPerSample == 8);
 419         unsigned char *buf = (unsigned char *)_TIFFmalloc(TIFFScanlineSize(tif));
 420         uint32 pos = 0;
 421         const bool minIsWhite = (photometric == PHOTOMETRIC_MINISWHITE);
 422         const int minValue =  minIsWhite ? 255 : 0;
 423         const int maxValue = 255 - minValue;
 424
 425         /*
 426         Decode to ABGR format as that is what the code, that converts to
 427         wxImage, later on expects (normally TIFFReadRGBAImageOriented is
 428         used to decode which uses an ABGR layout).
 429         */
 430         for (uint32 y = 0; y < h; ++y)
 431         {
 432             if (TIFFReadScanline(tif, buf, y, 0) != 1)
 433             {
 434                 ok = false;
 435                 break;
 436             }
 437
 438             if (isGreyScale)
 439             {
 440                 for (uint32 x = 0; x < w; ++x)
 441                 {
 442                     uint8 val = minIsWhite ? 255 - buf[x*2] : buf[x*2];
 443                     uint8 alpha = minIsWhite ? 255 - buf[x*2+1] : buf[x*2+1];
 444                     raster[pos] = val + (val << 8) + (val << 16)
 445                         + (alpha << 24);
 446                     pos++;
 447                 }
 448             }
 449             else
 450             {
 451                 for (uint32 x = 0; x < w; ++x)
 452                 {
 453                     int mask = buf[x*2/8] << ((x*2)%8);
 454
 455                     uint8 val = mask & 128 ? maxValue : minValue;
 456                     raster[pos] = val + (val << 8) + (val << 16)
 457                         + ((mask & 64 ? maxValue : minValue) << 24);
 458                     pos++;
 459                 }
 460             }
 461         }
 462
 463         _TIFFfree(buf);
 464     }
 465     else
 466     {
 467         ok = TIFFReadRGBAImageOriented( tif, w, h, raster,
 468             ORIENTATION_TOPLEFT, 0 ) != 0;
 469     }
 470
 471
 472     if (!ok)
 473     {
 474         if (verbose)
 475         {
 476             wxLogError( _("TIFF: Error reading image.") );
 477         }
 478
 479         _TIFFfree( raster );
 480         image->Destroy();
 481         TIFFClose( tif );
 482
 483         return false;
 484     }
 485
 486     unsigned char *ptr = image->GetData();
 487
 488     unsigned char *alpha = image->GetAlpha();
 489
 490     uint32 pos = 0;
 491
 492     for (uint32 i = 0; i < h; i++)
 493     {
 494         for (uint32 j = 0; j < w; j++)
 495         {
 496             *(ptr++) = (unsigned char)TIFFGetR(raster[pos]);
 497             *(ptr++) = (unsigned char)TIFFGetG(raster[pos]);
 498             *(ptr++) = (unsigned char)TIFFGetB(raster[pos]);
 499             if ( hasAlpha )
 500                 *(alpha++) = (unsigned char)TIFFGetA(raster[pos]);
 501
 502             pos++;
 503         }
 504     }
 505
 506
 507     image->SetOption(wxIMAGE_OPTION_TIFF_PHOTOMETRIC, photometric);
 508
 509     uint16 compression;
 510     /*
 511     Copy some baseline TIFF tags which helps when re-saving a TIFF
 512     to be similar to the original image.
 513     */
 514     if (samplesPerPixel)
 515     {
 516         image->SetOption(wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL, samplesPerPixel);
 517     }
 518
 519     if (bitsPerSample)
 520     {
 521         image->SetOption(wxIMAGE_OPTION_TIFF_BITSPERSAMPLE, bitsPerSample);
 522     }
 523
 524     if ( TIFFGetFieldDefaulted(tif, TIFFTAG_COMPRESSION, &compression) )
 525     {
 526         image->SetOption(wxIMAGE_OPTION_TIFF_COMPRESSION, compression);
 527     }
 528
 529     // Set the resolution unit.
 530     wxImageResolution resUnit = wxIMAGE_RESOLUTION_NONE;
 531     uint16 tiffRes;
 532     if ( TIFFGetFieldDefaulted(tif, TIFFTAG_RESOLUTIONUNIT, &tiffRes) )
 533     {
 534         switch (tiffRes)
 535         {
 536             default:
 537                 wxLogWarning(_("Unknown TIFF resolution unit %d ignored"),
 538                     tiffRes);
 539                 // fall through
 540
 541             case RESUNIT_NONE:
 542                 resUnit = wxIMAGE_RESOLUTION_NONE;
 543                 break;
 544
 545             case RESUNIT_INCH:
 546                 resUnit = wxIMAGE_RESOLUTION_INCHES;
 547                 break;
 548
 549             case RESUNIT_CENTIMETER:
 550                 resUnit = wxIMAGE_RESOLUTION_CM;
 551                 break;
 552         }
 553     }
 554
 555     image->SetOption(wxIMAGE_OPTION_RESOLUTIONUNIT, resUnit);
 556
 557     /*
 558     Set the image resolution if it's available. Resolution tag is not
 559     dependant on RESOLUTIONUNIT != RESUNIT_NONE (according to TIFF spec).
 560     */
 561     float resX, resY;
 562
 563     if ( TIFFGetField(tif, TIFFTAG_XRESOLUTION, &resX) )
 564     {
 565         /*
 566         Use a string value to not lose precision.
 567         rounding to int as cm and then converting to inch may
 568         result in whole integer rounding error, eg. 201 instead of 200 dpi.
 569         If an app wants an int, GetOptionInt will convert and round down.
 570         */
 571         image->SetOption(wxIMAGE_OPTION_RESOLUTIONX,
 572             wxString::FromCDouble((double) resX));
 573     }
 574
 575     if ( TIFFGetField(tif, TIFFTAG_YRESOLUTION, &resY) )
 576     {
 577         image->SetOption(wxIMAGE_OPTION_RESOLUTIONY,
 578             wxString::FromCDouble((double) resY));
 579     }
 580
 581     _TIFFfree( raster );
 582
 583     TIFFClose( tif );
 584
 585     return true;
 586 }
 587
 588 int wxTIFFHandler::DoGetImageCount( wxInputStream& stream )
 589 {
 590     TIFF *tif = TIFFwxOpen( stream, "image", "r" );
 591
 592     if (!tif)
 593         return 0;
 594
 595     int dircount = 0;  // according to the libtiff docs, dircount should be set to 1 here???
 596     do {
 597         dircount++;
 598     } while (TIFFReadDirectory(tif));
 599
 600     TIFFClose( tif );
 601
 602     // NOTE: this function modifies the current stream position but it's ok
 603     //       (see wxImageHandler::GetImageCount)
 604
 605     return dircount;
 606 }
 607
 608 bool wxTIFFHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbose )
 609 {
 610     TIFF *tif = TIFFwxOpen( stream, "image", "w" );
 611
 612     if (!tif)
 613     {
 614         if (verbose)
 615         {
 616             wxLogError( _("TIFF: Error saving image.") );
 617         }
 618
 619         return false;
 620     }
 621
 622     TIFFSetField(tif, TIFFTAG_IMAGEWIDTH,  (uint32)image->GetWidth());
 623     TIFFSetField(tif, TIFFTAG_IMAGELENGTH, (uint32)image->GetHeight());
 624     TIFFSetField(tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
 625     TIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
 626
 627     // save the image resolution if we have it
 628     int xres, yres;
 629     const wxImageResolution res = GetResolutionFromOptions(*image, &xres, &yres);
 630     uint16 tiffRes;
 631     switch ( res )
 632     {
 633         default:
 634             wxFAIL_MSG( wxT("unknown image resolution units") );
 635             // fall through
 636
 637         case wxIMAGE_RESOLUTION_NONE:
 638             tiffRes = RESUNIT_NONE;
 639             break;
 640
 641         case wxIMAGE_RESOLUTION_INCHES:
 642             tiffRes = RESUNIT_INCH;
 643             break;
 644
 645         case wxIMAGE_RESOLUTION_CM:
 646             tiffRes = RESUNIT_CENTIMETER;
 647             break;
 648     }
 649
 650     if ( tiffRes != RESUNIT_NONE )
 651     {
 652         TIFFSetField(tif, TIFFTAG_RESOLUTIONUNIT, tiffRes);
 653         TIFFSetField(tif, TIFFTAG_XRESOLUTION, (float)xres);
 654         TIFFSetField(tif, TIFFTAG_YRESOLUTION, (float)yres);
 655     }
 656
 657
 658     int spp = image->GetOptionInt(wxIMAGE_OPTION_TIFF_SAMPLESPERPIXEL);
 659     if ( !spp )
 660         spp = 3;
 661
 662     int bps = image->GetOptionInt(wxIMAGE_OPTION_TIFF_BITSPERSAMPLE);
 663     if ( !bps )
 664     {
 665         bps = 8;
 666     }
 667     else if (bps == 1)
 668     {
 669         // One bit per sample combined with 3 samples per pixel is
 670         // not allowed and crashes libtiff.
 671         spp = 1;
 672     }
 673
 674     int photometric = PHOTOMETRIC_RGB;
 675
 676     if ( image->HasOption(wxIMAGE_OPTION_TIFF_PHOTOMETRIC) )
 677     {
 678         photometric = image->GetOptionInt(wxIMAGE_OPTION_TIFF_PHOTOMETRIC);
 679         if (photometric == PHOTOMETRIC_MINISWHITE
 680             || photometric == PHOTOMETRIC_MINISBLACK)
 681         {
 682             // either b/w or greyscale
 683             spp = 1;
 684         }
 685     }
 686     else if (spp == 1)
 687     {
 688         photometric = PHOTOMETRIC_MINISWHITE;
 689     }
 690
 691     const bool isColouredImage = (spp > 1)
 692         && (photometric != PHOTOMETRIC_MINISWHITE)
 693         && (photometric != PHOTOMETRIC_MINISBLACK);
 694
 695     int compression = image->GetOptionInt(wxIMAGE_OPTION_TIFF_COMPRESSION);
 696     if ( !compression )
 697     {
 698         // we can't use COMPRESSION_LZW because current version of libtiff
 699         // doesn't implement it ("no longer implemented due to Unisys patent
 700         // enforcement") and other compression methods are lossy so we
 701         // shouldn't use them by default -- and the only remaining one is none
 702         compression = COMPRESSION_NONE;
 703     }
 704
 705     TIFFSetField(tif, TIFFTAG_SAMPLESPERPIXEL, spp);
 706     TIFFSetField(tif, TIFFTAG_BITSPERSAMPLE, bps);
 707     TIFFSetField(tif, TIFFTAG_PHOTOMETRIC, photometric);
 708     TIFFSetField(tif, TIFFTAG_COMPRESSION, compression);
 709
 710     // scanlinesize is determined by spp and bps
 711     const tsize_t linebytes =
 712         (tsize_t)((image->GetWidth() * spp * bps + 7) / 8);
 713
 714     unsigned char *buf;
 715
 716     if (TIFFScanlineSize(tif) > linebytes || !isColouredImage)
 717     {
 718         buf = (unsigned char *)_TIFFmalloc(TIFFScanlineSize(tif));
 719         if (!buf)
 720         {
 721             if (verbose)
 722             {
 723                 wxLogError( _("TIFF: Couldn't allocate memory.") );
 724             }
 725
 726             TIFFClose( tif );
 727
 728             return false;
 729         }
 730     }
 731     else
 732     {
 733         buf = NULL;
 734     }
 735
 736     TIFFSetField(tif, TIFFTAG_ROWSPERSTRIP,TIFFDefaultStripSize(tif, (uint32) -1));
 737
 738     const int bitsPerPixel = spp * bps;
 739     const int pixelsPerByte = 8 / bitsPerPixel;
 740     int remainingPixelCount = 0;
 741
 742     if (pixelsPerByte)
 743     {
 744         // How many pixels to write in the last byte column?
 745         remainingPixelCount = image->GetWidth() % pixelsPerByte;
 746         if (!remainingPixelCount) remainingPixelCount = 8;
 747     }
 748
 749     const bool minIsWhite = (photometric == PHOTOMETRIC_MINISWHITE);
 750     unsigned char *ptr = image->GetData();
 751     for ( int row = 0; row < image->GetHeight(); row++ )
 752     {
 753         if ( buf )
 754         {
 755             if (isColouredImage)
 756             {
 757                 // color image
 758                 memcpy(buf, ptr, image->GetWidth() * 3);
 759             }
 760             else if (spp * bps == 8) // greyscale image
 761             {
 762                 for ( int column = 0; column < linebytes; column++ )
 763                 {
 764                     uint8 value = ptr[column*3 + 1];
 765                     if (minIsWhite)
 766                     {
 767                         value = 255 - value;
 768                     }
 769
 770                     buf[column] = value;
 771                 }
 772             }
 773             else // black and white image
 774             {
 775                 for ( int column = 0; column < linebytes; column++ )
 776                 {
 777                     uint8 reverse = 0;
 778                     int pixelsPerByteCount = (column + 1 != linebytes)
 779                         ? pixelsPerByte
 780                         : remainingPixelCount;
 781                     for ( int bp = 0; bp < pixelsPerByteCount; bp++ )
 782                     {
 783                         if ( (ptr[column*24 + bp*3 + 1] <=127) == minIsWhite )
 784                         {
 785                             // check only green as this is sufficient
 786                             reverse = (uint8)(reverse | 128 >> bp);
 787                         }
 788                     }
 789
 790                     buf[column] = reverse;
 791                 }
 792             }
 793         }
 794
 795         if ( TIFFWriteScanline(tif, buf ? buf : ptr, (uint32)row, 0) < 0 )
 796         {
 797             if (verbose)
 798             {
 799                 wxLogError( _("TIFF: Error writing image.") );
 800             }
 801
 802             TIFFClose( tif );
 803             if (buf)
 804                 _TIFFfree(buf);
 805
 806             return false;
 807         }
 808
 809         ptr += image->GetWidth()*3;
 810     }
 811
 812     (void) TIFFClose(tif);
 813
 814     if (buf)
 815         _TIFFfree(buf);
 816
 817     return true;
 818 }
 819
 820 bool wxTIFFHandler::DoCanRead( wxInputStream& stream )
 821 {
 822     unsigned char hdr[2];
 823
 824     if ( !stream.Read(&hdr[0], WXSIZEOF(hdr)) )     // it's ok to modify the stream position here
 825         return false;
 826
 827     return (hdr[0] == 'I' && hdr[1] == 'I') ||
 828            (hdr[0] == 'M' && hdr[1] == 'M');
 829 }
 830
 831 #endif  // wxUSE_STREAMS
 832
 833 /*static*/ wxVersionInfo wxTIFFHandler::GetLibraryVersionInfo()
 834 {
 835     int major,
 836         minor,
 837         micro;
 838
 839     const wxString ver(::TIFFGetVersion());
 840     if ( wxSscanf(ver, "LIBTIFF, Version %d.%d.%d", &major, &minor, &micro) != 3 )
 841     {
 842         wxLogDebug("Unrecognized libtiff version string \"%s\"", ver);
 843
 844         major =
 845         minor =
 846         micro = 0;
 847     }
 848
 849     wxString copyright;
 850     const wxString desc = ver.BeforeFirst('\n', &copyright);
 851     copyright.Replace("\n", "");
 852
 853     return wxVersionInfo("libtiff", major, minor, micro, desc, copyright);
 854 }
 855
 856 #endif  // wxUSE_LIBTIFF