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November 2007

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2007.11.23 18:04 "Custom Tags and TIFFGetField", by Antonio Scuri

  Hi,

  I'm using TIFFGetTagListCount and TIFFGetTagListEntry to loop over all the
readed custom tags and import them to my own attribute system.

  But since _TIFFVGetField is highly tag dependent I had to use the
TIFFFieldInfo definition to interpret the tag type and count. I just checked
in libTIFF 4.0 from CVS and TIFFFieldInfo is marked as obsolete, but there
are no new functions that replace them.

  What I need is something like TIFFGetTagListEntryInfo that returns some
parameters of the actual tag readed from file like count and type. But I
also need field_passcount because _TIFFVGetField number of parameters depend
on it.

  Also from _TIFFVGetField:

						if ((fip->field_type ==
TIFF_ASCII
						    || fip->field_readcount
== TIFF_VARIABLE
						    || fip->field_readcount
== TIFF_VARIABLE2
						    || fip->field_readcount
== TIFF_SPP
						    || tv->count > 1)

  It will return an internal pointer instead of copying the data. So another
parameter describing this situation is necessary.


  Maybe I should implement two new functions that access libTIFF internal
data, called TIFFGetCustomFieldInfo(tag,&count,&type) and
TIFFGetCustomField(tag,array) with fixed parameters and a pre-allocated
array.

  Any suggestions?

Thanks,
Antonio Scuri