Re: Time handling in F-spot

[Paul Wellner Bou <paul purecodes org>]

Hi, again,

After looking into this again and a chat on irc on this I would like to 
correct and add some thoughts on this topic.

F-Spot is not assuming UTC, F-Spot assumes local time, shifts the dates 
to UTC and displays them in UTC.

Apart from the fact that I'd prefer no time shifting at all if not 
explicitely requested by the user, we have two issues:

1. EXIF date is shifted. If the time zone would be stored in EXIF, too, 
this wouldn't be an issue. But as it isn't, this leads to repeatedly 
shifting if reimporting in f-spot and it leads to eventually wrong time 
display in other applications that may have the same time policy as 
f-spot (although I don't know any which assumes changing EXIF data on 
its own).

2. The time displayed in F-Spot seems to be (the assumed) UTC time. The 
expected display time would be the local time where the photo was made. 
Do you agree?

This would fix the unexpected behaviour of the adjust time dialog, too, 
as the time set there will be the same time that will be displayed in 
the f-spot window. But it may raise another issue: As sorting is done on 
(assumed) UTC time, traveling through timezones will cause displayed 
times which are not in sort order (assuming that you set the timezone of 
the camera while crossing time zone borders). But this would be ok, as 
the real time sorting would be correct.

What do you think? Would this be a bug fix which is acceptable (fixing 
time display and not touching exif)? Next steps would be to write time + 
tz into xmp.

Regards
Paul.