[Sugar-devel] automatic backlight control

Paul Fox pgf at laptop.org
Mon Nov 21 15:55:51 EST 2011

bert wrote:
 > On 21.11.2011, at 18:06, Paul Fox wrote:
 > > bert wrote:
 > >> When you add the auto-turnoff, it should only toggle the backlight,
 > >> not the mono-color setting.  I don't think that would be too
 > >> confusing, from a user's POV it just means when it's bright
 > >> outside, the backlight's power gets cut.
 > >> 
 > >> I can see how it would lead to confusion if you map this desired
 > >> behavior onto the existing olpc-brightness command.  What's needed
 > >> I think is an additional "override" independent of the brightness
 > >> setting that just turns the backlight off.  Everything else would
 > >> stay the same.
 > > 
 > > it's not that easy.  unless neither brightness mechanism messes with
 > > the mono setting, then they need to be coupled somehow.  otherwise
 > > if the backlight is auto-offed (still color), then the user uses the
 > > "dim" key (no brightness change, but now mono), and then the backlight
 > > auto-ons, it will now be in mono.
 > That's not what I had in mind. Taking your example, the display would not 
 > auto-on since the user explicitly set it to off.
 > Auto-off should be completely independent of the user adjusting the brightness. 
 > E.g.:
 > Brightness is set to 10. User goes outside, ambient sensor overrides, turning 
 > backlight off. User presses brightness-down, level is set to 9. Backlight is 
 > still overridden due to ambient light. User goes inside, ambient override 
 > stops, backlight comes back on at level 9. 
 > See what I mean? The user shouldn't have to care about the ambient light sensor 
 > turning off the display. All the controls would still work the same. Just like 
 > on older XOs.

yes, i see.  but that's not really how i think a brightness control
works.  the control doesn't adjust a virtual target level of some
sort, for use in the future -- it simply adjusts the screen
brightness.  let me reword:

  Brightness is set to 10.  User goes outside, ambient sensor turns
  backlight off.  User presses brightness-down, level *doesn't change,
  because it's already 0*.  User goes inside, ambient override stops,
  backlight comes back on at level 10.

how does a switch to monochrome (and back to color) fit into that?

i think the only easy thing to do is what a couple of people have
suggested:  add an extra step to the manual control, such that if the
level is 0, and it's adjusted down, it switches to monochrome.  on any
upward adjustment it switches to color.  auto-turnoff would take it to
the 0-but-still-color level, and also always turn on color when
adjusting upward.

there's still an issue integrating with a "mono only" mode, since both
the manual and automatic controls would need to honor that.  and if any
other entity (e.g., sugar) wants to join in the fun, they'll have to
honor that mode too.


 > > do you also object to the new color/mono toggle, via the control
 > > key (or via the UI)?
 > Not at all.
 > > please try os12, when available, and see how it feels.
 > > 
 > > paul
 > Will do.
 > - Bert -
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 paul fox, pgf at laptop.org

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