Add ability to inhibit idle on windows

[griccardos]

This adds the ability to inhibit idle on a window if configured.

There are a few discussions about the topic
#742
#1855

There are 3 options:

• inhibit_idle "always" - whenever this window is present.
• inhibit_idle "fullscreen" - whenever this window is fullscreen
• inhibit_idle "never" - don't inhibit on this window

Option 1 is useful, for example converting a video file that may take a couple of hours, but the window itself is not necessarily fullscreen

window-rule {
    match title="HandBrake"
    inhibit-idle "always"
}

Option 2 is useful, for example when you are watching video, playing games with a controller and the window is fullscreen

window-rule {
    match app-id="librewolf"
    inhibit-idle "fullscreen"
}

Option 3 is to disable inhibit on this window for example if you have enabled inhibit fullscreen on all windows, but you want this window as the exception not to inhibit when fullscreen

window-rule {
    inhibit-idle "fullscreen"
}
window-rule {
    match app-id="Alacritty"
    inhibit-idle "never"
}

[HigherOrderLogic]

inhibit_idle "never" in this PR doesnt make sense. From a quick skim of your PR, seems like the client still can dispatch an idle inhibitor through the Screensaver Dbus and inhibit the compositor.

[griccardos]

@HigherOrderLogic
Perhaps never is the wrong term. The aim of never, is not to prevent inhibiting but to override a parent rule. Like in my example, I want to inhibit idle on all windows that are fullscreen with the exception of alacritty.
perhaps renaming it to none?
Open to suggestions on the naming...

[HigherOrderLogic]

perhaps renaming it to none?

Yeah, "none" seems like a better name here.

[YaLTeR]

The aim of never, is not to prevent inhibiting but to override a parent rule.

I believe we use null for this

[griccardos]

The aim of never, is not to prevent inhibiting but to override a parent rule.

I believe we use null for this

Yes, I can implement null for this case.

We will still need a 3rd variant as there are 4 cases:

• "always" - Some(Always)
• "fullscreen" - Some(Fullscreen)
• null - Use default irrespective of previous window rules - Some(Default)
• user leaves it out - Use previous window rules. - None

Pehaps we can call the 3rd variant Default

[YaLTeR]

I think I used Option<Option<T>> elsewhere

[griccardos]

Thanks for the tip, Option<Option<InhibitIdle>> worked nicely.
I have made the changes.
I've also done some testing and it works as expected.

[nagisa]

Should a way to inspect idle inhibitors (and inhibition reasons) be added as well? Could be a field in niri msg windows.

[YaLTeR]

It's tricky. There's Wayland idle inhibit, which has no reason. There's the D-Bus one that has no association to a window.