[support-gang] XO brightness key operation

[Nicholas Doiron]

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.

--
Nick Doiron
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
> =---------------------
>  paul fox, pgf at laptop.org
> _______________________________________________
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> support-gang at lists.laptop.org
> http://lists.laptop.org/listinfo/support-gang
>
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