[Korganizer-devel] [Bug 184628] Recurring events created in KDE 3.5 MUST be converted to local time zone to result in the same recurrence dates

[Reinhold Kainhofer]

https://bugs.kde.org/show_bug.cgi?id=184628

           Summary: Recurring events created in KDE 3.5 MUST be converted
                    to local time zone to result in the same recurrence
                    dates
           Product: korganizer
           Version: 4.2.0
          Platform: Ubuntu Packages
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: korganizer-devel at kde.org
        ReportedBy: reinhold at kainhofer.com


Version:            (using KDE 4.2.0)
OS:                Linux
Installed from:    Ubuntu Packages

Recurring events were treated in KDE 3.5 as if the DTSTART was given in local
time (even though they were written out in UTC). In particular, while the
DTSTART was stored in UTC, it was immediately converted to the local time zone
when loading the event. The RRULE was then calculated starting from the start
time in LOCAL TIME.

In KDE 4 they use the TZ given for the DTSTART, so the recurrence instances are
calculated from the DTSTART as given in UTC (which might be a different date)
and only afterwards converted to the view's timezone.

So the DTSTART **MUST** be converted to the local time zone on loading (can be
done using a compat rule). Otherwise, all events where the start time in UTC
and in the local time zone are on different dates (e.g. an event at 0:30 CET,
which is stored as 23:30 UTC on the previous date) are possibly displayed on
the wrong dates.

As an example, I'm attaching a sample file generated with KOrganizer 3.5.x to
be loaded with Europe/Vienna as the local time zone. If you look at the
recurrence instances in KOrganizer 3.5 and 4.x, you'll see that they appear on
different dates. This is one of the worst problems, because it means that you
can no longer trust any date in your calendar!

The solution is to simply add a compat rule for files created with KOrganizer
<= 3.x and convert all UTC times (at least for recurring incidences) to local
time with the configured TZ attached. This way, the interpretation will be the
same as in 3.5.

-- 
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.