Detecting when PopupApplet is iconified

[Marco Martin]

On Friday 19 March 2010, Sebastian Kügler wrote:
> On Friday 19 March 2010 17:21:37 Aaron J. Seigo wrote:
> > On March 18, 2010, Rob Hasselbaum wrote:
> > > On Thu, Mar 18, 2010 at 11:04 AM, Marco Martin <notmart at gmail.com> 
wrote:
> > > > what are you exactly trying to accomplish?
> > 
> > thanks for asking the Right Question(tm) :)
> > 
> > > > usually you shouldn't care of a detail like that
> > > 
> > > I have a data engine that pushes data to my applet asynchronously. When
> > > the applet isn't being shown, I want to disconnect from the source to
> > > reduce CPU overhead.
> > 
> > i can think of various hacks to accomplish this, but they aren't
> > particularly pretty and i only know they'll work because i know how
> > things work internally (which is never a good sign for a "solution" ;)
> > 
> > i think the only clean solution to this would be to offer a bool
> > PopupApplet::isIconified() const method.
> > 
> > btw, i sat here for a few minutes trying to discount your use case, but
> > it is a valid one imho. if it is't being shown to the user, the applet
> > should at least have a chance of not waking up the cpu.
> > 
> > my only question now is how to handle notification of the change. my
> > first thought would be to add a new Contraint (IconifiedConstraint?) and
> > then the applet could respond in constraintsEvent.
> 
> It's not only about being iconified, the applet could also be one a
> containment that's not shown, or on the dashboard (separate from the
> desktop background and invisible).
> 
> I wonder if we could just offer queueing updates from dataengines until an
> applet is about to be shown. Especially for mobile devices, this "not
> waking up unless shown" can be very important.

yes, i think it should be generalized to catch those cases as well.
also to be careful to not make it too rigid since we could want updates in a 
popupapplet too if the icon or the widget that replaces the icon is dependant 
from the data of the dataengine (clock, microblog, weather...)

so, cases could be:
-closed popupapplet
-containment without screen()
-separate dashboard (even worse, that is a containment that is never assciated 
to a screen, but someties shown)

the way that would be killer would be to actually know if a given widget is 
shown by at least one view (that is in this moment actually visible) or not, 
but i don't think there a re -efficient- ways to do that

Cheers,
Marco Martin