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October 2009
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2009.10.28 16:02 "Re: extending tags in "a"ppend mode?", by Frank Warmerdam
Juergen Buchmueller wrote: > Hi list, > > should it be possible to extend the tags of (the first directory of) an > existing tiff file opened in "a"ppend mode? > > What I'm trying to do is: > + open an existing tiff file with TIFFOpen(...,"a") > + create an array of TIFFFieldInfo > + call TIFFMergeFieldInfo() with this array and count > + Write some (string) tags that were defined in the array > + close the tiff handle with TIFFClose() > > It seems that TIFFClose() hangs somewhere and doesn't return, which is > why I suspect that what I'm trying to do is impossible. Juergen, It should be possible to extend the first directory with new tags by opening in "r+" (update) mode, setting the tags and closing. I don't know why you are seeing the behavior you encountered. I would have expected it to attempt to append a new image directory and complain about your not providing a complete set of tags to define an image. It might be helpful if you provided a minimal program and file demonstrating your problem. Also, in place update of directories is always an iffy procedure with libtiff but I would strongly encourage using the most recent release (3.9.1?) if you are trying this. Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent