On 3/27/07, Danny Kukawka <[EMAIL PROTECTED]> wrote:
On Dienstag, 27. März 2007, Richard Hughes wrote:
> First, there might be more than a single backlight
- the tool which provide the interface have to handle this or the get/set
methodes have to take/return arrays with info for each display. But the major
use case on laptops this is IMO not really needed, there is the internal
display the thing you want to change

Arrays? Maybe add another param that is the HAL ID of the device to
both get and set and add a method to easily enumerate the devices
(return an array of all known IDs and names).

> Secondly, exporting the brightness as percentage sucks
No, it does not. It make no sense to export e.g. all ~250 brightnesslevel of a
Panasonic laptop display. If you want to change the display brightness of
such a display e.g. with a slider in the GUI you produce high system load and
many calls to HAL/in HAL. And you can't see the difference between level 170
and 172.

But it does suck if your LCD only supports ~17 brightness levels and
calculating percentage gives you fractions. How do you handle
brightness up/down controls there?

- Internally keep the current counter and each time it changes map it
to the closest handled by LCD?

- Each time it changes reset it to the closest value (would require
the application to incrementally try to increase brightness untill
there is a change)

Mapping the existing level to percentage make much sense. This allow you also
to use your settings on different machines with different brightness level
(if you use e.g. a NFS home).

It should be kept as a per-device setting, not global. What if I have
a really bright LCD at one location/machine and a really dim one at
the other?

Btw. the mapping to percentage should maybe happen in HAL directly.

I think this really belongs to the GUI part of the application, not
the hardware abstraction.

> Move the backlight stuff to their own D-Bus
> objects: /org/freedesktop/PowerManagement/BackLighDevices/backlight0 and so
> on. (better use some HAL device name for naming the object)
Make maybe sense, but why do we need these new interfaces which are somehow
only duplicates of the HAL stuff? Would it not make more sense to only
provide one interface to all display backlights (set brightness to 50% would
set it to all displays) or only to the primary display (would make sense on
laptops)? For all other interfaces you can use HAL also directly or not?

It makes sense only for laptops. What if I use an UPS and want all the
monitors but the main one to either turn off or get as low in
brightness as possible in case of power failure?

Or I don't want to touch the one that has an auxiliary power source?

--
Patryk Zawadzki
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