[maemo-developers] Optimal battery life considerations in apps

[From: Andrew Flegg]

Hi,

There are two main things (AIUI) an app should do when running on
Maemo to conserve battery life:

    1) Listen for the device_state_change system_inactivity = 1
       DBUS signal and stop updating until = 0 is received.
       This covers the screen blanking.

    2) Stop updating the screen when your app isn't in the
       foreground.

(1) is trivial to implement. (2) is trickier (there's
hildon_program_is_topmost() and hildon_window_is_topmost(), but
polling to discover when you're topmost again is hideous). There
doesn't seem to be a good, simple, authoritative reference on these
techniques; demonstrating implementations in various languages (an
ideal candidate for a wiki page).

I'm willing to put together this wiki page but have two questions:

    1) What is the best way of implementing (2) in C/Python/whatever?

    2) In Fremantle, there's a compositing window manager. On a
       desktop this means you never receive an "expose" event
       since your window is always exposed on an off-screen
       buffer. What is the best way of implementing (2) in
       Maemo 5?

Thanks in advance,

Andrew

-- 
Andrew Flegg -- mailto:andrew at bleb.org  |  http://www.bleb.org/
Maemo Community Council chair