AWARE [SYSTEMS]
AWare Systems, , Home TIFF and LibTiff Mailing List Archive

LibTiff Mailing List

TIFF and LibTiff Mailing List Archive
February 2004

Previous Thread
Next Thread

Previous by Thread
Next by Thread

Previous by Date
Next by Date

Contact

The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems



New Datamatrix section



Valid HTML 4.01!



2004.02.20 15:41 "bug in libTiff", by Nick Basargekar

There appears to be a bug in libTIFF 3.6.1(for win32) which prevents the
writing out of changed TIFF fields.  

*
 * Flush buffered data to the file.
 *
 * Frank Warmerdam'2000: I modified this to return 1 if TIFF_BEENWRITING
 * is not set, so that TIFFFlush() will proceed to write out the directory.
 * The documentation says returning 1 is an error indicator, but not having
 * been writing isn't exactly a an error.  Hopefully this doesn't cause
 * problems for other people. 
 */

int
TIFFFlushData(TIFF* tif)
{
        if ((tif->tif_flags & TIFF_BEENWRITING) == 0)
               return (0);
        if (tif->tif_flags & TIFF_POSTENCODE) {
               tif->tif_flags &= ~TIFF_POSTENCODE;
               if (!(*tif->tif_postencode)(tif))
                       return (0);
        }
        return (TIFFFlushData1(tif));
}
 

Frank's comment's don't make any sense because returning 0 is an error
indicator according to the docs. 

So I changed it to 

        if ((tif->tif_flags & TIFF_BEENWRITING) == 0)
                return (TIFFFlushData1(tif));

and then reading/writing of fields started working. 
 

Basically, I'm trying to write out a byte array to a private field for use
within this organization. 

The contrib\tags example in libTiff doesn't appear to be compatible with
3.6.1, so I  followed the instructions at
http://www.libtiff.org/internals.html#AddingTags
<http://www.libtiff.org/internals.html#AddingTags>  and along with the
change mentioned above, reading/writing of the private field works ok with
libTiff.  

However Windows Preview can't view the file after the tag is added.
Photoshop 7.0 gives a nasty warning dialog about the file possibly being
corrupt, but the file seems to open fine.  

I found that even changing a "normal" field like "TIFFTAG_ARTIST" caused the
same problems.  I'm just wondering if anyone has encountered a similar issue
or has any info on the subject.  Any feedback at all is greatly appreciated.

Nick Basargekar
Software Engineer, Core Technology Group
PEI/Atari, Inc. 
http://www.atari.com <http://www.atari.com>