2004.02.20 15:41 "[Tiff] bug in libTiff", by Nick Basargekar
Thread
2004.02.20 15:41 "[Tiff] 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