[Panel-devel] engines, animators, oh my

[Aaron J. Seigo]

On Monday 11 June 2007, Michael Olbrich wrote:
> And how do we decide what the correct polling frequency for a DataEngine
> is? Let's use the example of the time DataEngine. Maybe I want a clock
> applet with a resoution of 0.1 seconds. To do that the DataEngine has to
> provide 10 updates/second. Another clock applet only shows hours and
> minutes. Now I now disable the high resolution clock. Will the
> DataEngine still provide 10 updates/second?

way ahead of you. =) this is the sort of things that kevin and i discussed the 
other day. my thoughts are that we need to keep the configuration parameters 
with each applet, aggregate from the applets and allow engines to define 
whether numerical settings (int, float and, bending the definition a bit, 
bool) should be aggregated towards the maximum or minimum.

> If so the end the DataEngine has to use the maximum polling frequency
> even if no currently active applet needs sucha high resolution.

as applets disappear then the configuration request for the higher resolution 
does as well. remember as well that this would -only- be an issue until next 
reload/reboot. so we're dealing with a situation that exists only when the 
user takes a certain set of steps and which is, by definition, temporary.

it's important to keep these issues in mind, but it's more important to keep 
the common cases the priorities so that we don't design a system that covers 
corner cases perfectly but which makes the common needs difficult. in this 
case the common need is to make writing applets dead simple.

(rss feeds are an even more interesting use case for this topic, btw.)

> And how should we decide what the maximum polling frequency is?

see above

> Maybe we could load DataEngines multiple times with different
> parameters? 

which completely loses us the benefits of sharing resources and once again 
introduces the even worse situation of having multiple timers in the more 
common case. in the case of the clock, the common cases are, in decreasing 
order:

- having 1 clock with multiple timezones
- having 2 or more clocks with different timezones showing but the same 
resolution (i even received bug reports from such configurations when there 
was an odd TZ issue back in kde 3.something; so i know these configurations 
exist and aren't that rare)
- having 2 or more clock with different resolutions (i've yet to see this one 
=)

-- 
Aaron J. Seigo
humru othro a kohnu se
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43

Full time KDE developer sponsored by Trolltech (http://www.trolltech.com)
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