Inrtoduce BrightnessManager dbus interface

[garaevdi]

With gnome 49 screen brightness management was moved into mutter. This is a simple and naive implementation of backlight interface which could be controlled via DBus.

Note: to build this you would need mutter 50.2

[leolost2605]

Did you check whether it might already be exposed via org.gnome.mutter.displayconfig ?

[garaevdi]

Did you check whether it might already be exposed via org.gnome.mutter.displayconfig ?

Yes, but I think it's better to abstract it with a gala interface. Otherwise both switchboard-plug-power and wingpanel-power would need to implement the same things (handling monitors changes, converting raw brightness values to percentages).

_{Also you won't have to deal with complicated dbus types}

[leolost2605]

Yes, but I think it's better to abstract it with a gala interface. Otherwise both switchboard-plug-power and wingpanel-power would need to implement the same things (handling monitors changes, converting raw brightness values to percentages).

Hmm yeah that makes sense. Also I just saw there are vague plans to drop the backlight from the dbus api anyways 😅
Though I think we should use having to implement this to already prepare for individual multi monitor backlight control which AFAIR is the reason why gnome moved the brightness control into mutter.

Also ig we have to implement save and restore too since it was dropped from mutter (though that only made 51 so ig we can follow up):
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4814
https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/4006

[garaevdi]

@leolost2605 Rebased onto main and added keyboard shortcuts.
Not sure why this builds on development-target tho... IIRC mutter was missing includes in its' public headers. A fix is already there, but it is only available since 50.2, while resolute ships 50.1

[leolost2605]

Though I think we should use having to implement this to already prepare for individual multi monitor backlight control which AFAIR is the reason why gnome moved the brightness control into mutter.

Any thoughts on this? I'd like to do it now because it requires a different public API.

[garaevdi]

Though I think we should use having to implement this to already prepare for individual multi monitor backlight control which AFAIR is the reason why gnome moved the brightness control into mutter.

Any thoughts on this? I'd like to do it now because it requires a different public API.

Not really, IMO some kind of manager object is still needed to provide a way to control "global" brightness scale or perhaps lock other monitors' scales to a global one. The last commit does something like this, but it's super WIP.

(And also it wouldn't compile due to another missing include in mutters' headers 🫠️)

[leolost2605]

"global" brightness scale

Yeah I was wondering if we even need that? I mean what would be the "global" scale if you have two monitors which both support brightness adjustment?

I had a quick look through your new commit and I think I wouldn't do individual dbus objects for individual monitors. The interface isn't expected to grow much bigger and having a single interface and addressing via an index is much simpler for the user of the interface IMO.

Maybe something like this:

// Core part
signal void monitors_changed ();
signal void monitor_brightness_changed (uint index);

void set_monitor_brightness (uint index, int brightness);
int get_monitor_brightness (uint index);
string get_monitor_name (uint index);
int get_n_monitors ();

// Some utilities
// For keybinds?
set_primary_monitor_brightness (int brightness);

// Idk do we want that?
set_all_monitor_brightness ();

• The index doesn't actual mean anything and it is only guaranteed to address the same monitor until the next monitors_changed