Re: [Evolution-hackers] [evolution-kolab] Datastructures for calendar data

[Milan Crha <mcrha redhat com>]

On Wed, 2010-09-29 at 17:15 +0200, Hendrik Helwich wrote:
> So one option for us is to operate on the icalcomponent instead of 
> ECalComponent.

	Hi,
internally yes, but remember, the ECalBackend API uses ECalComponent in
most cases.

> In our project we do not need any time zone information which is attached to 
> time data. It would be sufficient if all time data is stored in UTC format. 
> Then we could stay with the ECalComponent class.
> Is there an easy way in evolution to strip timezone information from an 
> ECalComponent by converting local time data to UTC time data?

Well, timezone information is crucial for users, usually, and you might
not change they will to use always UTC. You know, when you are adding a
new appointment into a calendar, then you can choose your own timezone
(View->Timezone), also a different one from that used in Evolution
(which is used as a default timezone).

Imagine a user, a businessman, whom is living in US and cooperates with
a Europe partner on regular bases. Say they have a phone meeting twice a
month, which is held in Europe in some certain time. So our businessman
living in America/New_York will enter his meeting in Europe/Berlin, and
he'll see this in his timezone (because he has it set in Evolution),
even though the internal ECalComponent timezone is Europe/Berlin. What
is it good for? I believe you know. It's good because changes from
summer to winter time and vice versa are done in different weeks in
these timezones, and because the organizer is in Europe, then the New
York time will be shifted accordingly based on Europe time in these
periods, so our business man will not miss his meeting. If you would
change timezones for all your components to UTC then the times may be
wrong.

The other thing is that whenever there is recognized an event in
different than Evolution user's timezone, Evolution is showing an icon
about it on the event.

Nonetheless, to answer your question, I didn't find an ECalComponent
function for converting times between timezones, though I didn't search
heavily, but there is used a libical function icaltimezone_convert_time
for it.
	Hope that helps,
	Milan