[support-gang] XO brightness key operation
ndoiron at mapmeld.com
Mon Apr 9 12:20:19 EDT 2012
Is there a way to read the current value of the 1.75's ambient light
sensor? It'd be neat if that could be displayed by an activity.
Code for America
On Apr 9, 2012 9:16 AM, "Paul Fox" <pgf at laptop.org> wrote:
> i just sent this to the folks working on the current doc sprint, and
> then realized it probably deserves a wider audience. operation of the
> brightness keys was enhanced a bit in 11.3.1, based on discussion on
> the devel list, but i don't recall that i ever sent out a summary mail.
> for convenience, i'm going to refer to the brightness keys as BrUp and
> BrDown here.
> on all laptops, in all sofware releases to date:
> - the unmodified BrUp and BrDown keys adjust the brightness in 15
> steps. when turning the backlight all the way off (i.e.,
> the lowest setting) the display will switch into the higher
> resolution monochrome mode.
> - using the Alt-BrUp and Alt-BrDown combinations will immediately
> change the backlight to its maximum and off values (including the
> change to monochrome when off).
> in release 11.3.1 and later, on all laptops:
> - the Ctrl-BrUp and Ctrl-BrDown combinations don't actually change
> the backlight level, but rather will toggle the screen between
> "normal" mode and the higher resolution monochrome mode. this
> monochrome mode will be sticky, so further normal use of the
> keys will adjust the brightness but won't restore color. this
> can be useful if you want the higher resolution, and don't
> currently need to have color displayed. unfortunately, there
> is currently no way to enter this "semi-permanent monochrome
> mode" via the Sugar user interface -- only Ctrl-BrDown will do it.
> and finally, on XO-1.75 only:
> - the backlight may automatically turn off when the laptop is in
> bright sunlight. when this happens, it is _not_ put into the
> hi-res monochrome mode. when the light level returns to
> "normal" -- i.e., indoor or shady light -- the backlight will
> be restored to its previous value.
> the ambient light sensor shares the opening in the plastic
> with the LED that looks like "(o)" near the lower left corner
> of the screen, so covering that location when outside, or
> shining a bright light on it when inside, may cause the
> backlight level to change.
> it's also worth noting that the F9 and F10 keys are, by default, the
> brightness keys, and are intercepted by system software before a
> running program can receive them. if the Fn key is pressed at the
> same time as F9 or F10, then the keys instead generate the true F9 and
> F10 codes, and are available to the current application (or perhaps
> the window manager). this is also true of the volume keys on F11 and
> F12 -- on any of our keyboards, holding Fn will force the top row of
> keys to generate F1 through F12.
> finally: all of the above functionality is available from the
> shell commandline:
> $ olpc-brightness -h
> usage: olpc-brightness [up|down|max|min|<0-15>|color|mono]
> paul fox, pgf at laptop.org
> support-gang mailing list
> support-gang at lists.laptop.org
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