desktop: Add gamemode support

[kjarosh]

Fixes #17895.

This PR adds gamemode support through ashpd (Linux-only).

• There are 3 values for the gamemode setting:
  • Off—gamemode is disabled,
  • On—gamemode is enabled,
  • Default—gamemode is enabled only on high power preference.
• A CLI option --gamemode is added.
• A GUI is added to the preferences.

Gamemode is requested only when a SWF file is loaded.

TODO:

• Add a tooltip which describes what Default does.
• Switch away from ashpd git when desktop/game_mode: Use i32 for pid bilelmoussaoui/ashpd#234 is released.

[torokati44]

Bah, deny.toml also has to be updated to allow the new git source explicitly... Sorry for the added trouble!

Also, just curious, what made you go with ashpd over zbus directly? I assume the readily available (even if buggy) high level support for this specific use case - in which case, great!

But technically, ashpd, outside of a Flatpak jail, just does a DBus call or two; and zbus also works over Flatpak, right?

[kjarosh]

just curious, what made you go with ashpd over zbus directly? I assume the readily available (even if buggy) high level support for this specific use case - in which case, great!

That's true.

But technically, ashpd, outside of a Flatpak jail, just does a DBus call or two: and zbus also works over Flatpak, right?

That's also true.

I could go with zbus and write the proxy myself, but we depend on ashpd anyway (through rfd) and using ashpd we don't have to worry about D-Bus names and types, which is a value added.

However, if we have good reasons to stick with zbus, I can also switch to it.

(I'm also considering rewriting our FreedesktopSettings to use ashpd for the same reasons.)

[torokati44]

However, if we have good reasons to stick with zbus, I can also switch to it.

No, quite the opposite, in agreement with you. I was just checking my assumptions.

[Dinnerbone]

CI only lints on linux so I'll pretend to be a bot for a moment.

warning: field `gamemode_preference_readonly` is never read
  --> desktop\src\gui\dialogs\preferences_dialog.rs:24:5
   |
11 | pub struct PreferencesDialog {
   |            ----------------- field in this struct
...
24 |     gamemode_preference_readonly: bool,
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(dead_code)]` on by default

warning: method `show_gamemode_preferences` is never used
   --> desktop\src\gui\dialogs\preferences_dialog.rs:304:8
    |
52  | impl PreferencesDialog {
    | ---------------------- method in this implementation
...
304 |     fn show_gamemode_preferences(
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^

warning: function `gamemode_preference_name` is never used
   --> desktop\src\gui\dialogs\preferences_dialog.rs:556:4
    |
556 | fn gamemode_preference_name(
    |    ^^^^^^^^^^^^^^^^^^^^^^^^

[kjarosh]

Dinnerbot? 👀

[adrian17]

Now that I look at it, this ends up adding a pointless warning on windows by default :(

[kjarosh]

#18242