On Tuesday 14 January 2014 13:05 Graham Cobb wrote: > On 14/01/14 01:14, Thomas Tanghus wrote: > > On Tuesday 14 January 2014 01:53 Ove Kåven wrote: > >> No matter what OS or platform you're on, counting the number of times > >> your timer callback is called is *never* a good idea, even on desktop > >> PCs. Timer callbacks can be skipped for any number of reasons (heavy > >> system load, laptop suspend, etc). > > > Good point. That will also at least work around the issue when in > > "pre-deep- sleep". > > I agree with Ove (that is how every timer function I have ever worked on > works, from interrupt handlers in embedded system kernels through to the > GPE Calendar app) -- repeating timers are a convenience, but are never > treated as accurate. > > But I would also suggest that for any apps that do timing, when the app > is not being displayed (and so the screen doesn't need to be updated), > the code should switch to using a single-shot timer set to the time when > the next event happens, instead of using repeating timers. If the > kitchen timer is set for 25 minutes and the screen is blank you don't > want your app waking up every second. Of course, it is a little bit > tedious to write the code to cancel the long timer and restart short > timers when the screen is turned back on but the user will thank you for it.
It sounds like a good idea, and should be fairly easy to implement. I just don't know how to detect when the screen is off (this is my first baby-steps in mobile coding). We have the applicationActive property, but the cover can still be active and visible while it is false. > Unfortunately, I have no idea how you actually set up a single shot > timer that will fire correctly in deep sleep from the Qt environment > (the last time I implemented that logic was on Maemo). Rainisto pointed to libiphb[1] which I have now implemented with a crude wakeup every 5-10 seconds. Not optimal, but I'm OK with it for v 0.1.1 ;) [1] http://talk.maemo.org/showpost.php?p=1401318&postcount=2 -- Med venlig hilsen / Best Regards Thomas Tanghus _______________________________________________ SailfishOS.org Devel mailing list