XMP tags : Embedded vs Sidecar.

[Bengt Thuree <bengt thuree com>]

On Thu, 2006-07-27 at 18:30 +0200, Mattias Holmlund wrote:

> Using the modification time-stamp is by no means foolproof, but it
> will probably do the right thing in the majority of cases. If the
> image and the sidecar has the same modification time-stamp, we can
> assume that both files were last touched by the same application and
> since that application created a sidecar, the relevant information is
> probably in the sidecar.

How about if they are copied around, and the timestamp is modified...

> 
> Another alternative is to always use the sidecar, since if this is
> wrong, then it is easy for the user to delete the sidecar and try
> again, but it is very hard for the user to delete the embedded xmp and
> try again.

How about starting reading a sidecar's information (if it exists), and
then read the picture's information. (This way the picture will always
take precedence). 
I can also create a new tag, (I know, forbidden... but look at it as a
temporary solution) indicating which photos have an Sidecar associated
with them.
Of course, right now F-Spot do not import (read copy) the sidecar with
the photo, so my code looks both in the imported (Photos) location as
well as on the original place. Which is not good, but at least we read
the tags...
The patch could also check for tags set both in the sidecar as well as
in the picture, and if they differs notify the user (gui?)
I'm not sure how much effort we should put into this though.

/Bengt