On Mon, 04 Feb 2002, Lutz Müller wrote:
 > On Mon, 2002-02-04 at 14:29, Dave Neary wrote:
 > >Thereare a couple of other libraries which do pretty much the same
 > >thing -
 > >see the relevant bug numbers in bugzilla (not sure what they are right
 > >now).
 > >I haven't had a chance to look closely at this, but it looks good.
 > There is python stuff, a C++ library, lots of programs, but no plain C
 > library. Plus, everything out there is designed for _extracting_ EXIF
 > data, not _editing_ it. This is why I designed libexif(-gtk).

 From the GIMP's point of view (or at least from my point of view),
editing and importing/exporting EXIF data are two different things
that should not be mixed.

Importing and exporting EXIF data (or other meta-information) should
be done by the file plug-ins, as explained in this bug report:
The basic idea is that each file plug-in that supports metadata can
convert the EXIF data (or other meta-data) to/from GIMP parasites.
When saving a file (e.g., TIFF, JPEG or PNG), the corresponding file
plug-in would try to convert as many of these parasites as possible to
the appropriate format (EXIF or TIFF/EP).  Note that it is important
that each individual item in the EXIF data is converted to a separate
GIMP parasite instead of importing the whole EXIF data in one big
chunk because some parts of the EXIF data must be modified when the
image is re-saved (also, some file formats do not support all fields
so it is easier to work with them if they are saved in separare

Editing the metadata should be done by the core of the GIMP or by a
separate plug-in.  See this other bug report (and the ones linked from
it) for a description of what is needed:
This feature should be accessible through <Image>->File->Properties...
and it would be used to edit the image comment, resolution info, etc.

It should probably not be limited to the EXIF data, though.  It should
also be able to edit other GIMP-specific properties of the image.  The
main idea is to have a more user-friendly and more powerful version of
the parasite editor.

 > So I am the third person looking at it :-)
 > I just don't know how to handle the dependency on libexif(-gtk). You
 > know, libexif itself is quite small and could be included in gimp
 > (although I'd keep it separately), but libexif-gtk is getting bigger and
 > bigger as more widgets are added. Therefore my question: Is it ok to
 > introduce a (conditional --enable-exif) dependency on libexif(-gtk) for
 > gimp?

Well, I don't know what is the best thing to do.  libexif should
probably be integrated directly into the JPEG plug-in (and maybe
adapted for the TIFF and PNG plug-ins) but I assume that large parts
of it would have to be rewritten in order to use GIMP parasites as the
storage format for all data.

The user interface (libexif-gtk) could be a good start for a generic
metadata editor ("file properties") in the Gimp, but again I am afraid
that large parts of it would have to be rewritten in order to remove
the dependencies on EXIF and work from GIMP parasites.

It would be very nice if you could re-write your code to have it based
on GIMP parasites because that would provide some features that have
been missing from the GIMP for a long time.


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