add lxqt-palette.conf for builtin themes

[antis81]

Colors are based on the "Ambience" theme which served as reference for a dark theme.

Reference Screenshot:

Note: The palettes don't have any effect until implementation in liblxqt is done.

Further steps:

• liblxqt should fallback to a default palette (see lxqt-config-appearance -> defaultPalette()) if no lxqt-palette.conf file is provided by a theme.
  (especially important for "third-party" themes like e.g. "ArcMaia")

Builtin "dark" themes TBD:

• kvantum (dark theme?)

Builtin "light" themes TBD:

• light
• kde-plasma (light theme)
• clearlooks (light theme)

Special cases:

• system (not an LXQt theme)

[tsujan]

These files don't have any meaning yet and this PR shouldn't be merged. So, I'm converting it to a draft.

You first need to give them meaning by writing code for lxqt-config. Then, this could be changed to a PR again.

[antis81]

These files don't have any meaning yet and this PR shouldn't be merged. So, I'm converting it to a draft. …

Sure, the topic actually spreads across these four LXQt modules:

• lxqt-theme
• lxqt-config-appearance
• lxqt-qtplugin (QPalette becomes effective here at runtime; no code modification needed now!)
• liblxqt (holds LXQtTheme singleton)

By moving the context completely to lxqt-qtplugin (take it as in "QWidget support") at the very least the liblxqt dependency can be resolved and vanishes. However this is maybe for a mid-term goal (milestone?)…

[tsujan]

By moving the context completely to lxqt-qtplugin

No, lxqt-qtplugin doesn't need to be touched for this. As said before, applying palettes is only related to lxqt-config; no other component should be cluttered.

[tsujan]

Let me explain it again:

The logic is as simple as this: Appropriately add code to lxqt-config for optionally applying ready-made palettes consisting of 8 colors that we support.

lxqt-config can already apply 8-color palettes by writing to ~/.config/lxqt/lxqt.conf. This is just about reading those 8 colors from specific files inside lxqt-themes — like the files you've added here — nothing more.

[stefonarch]

If I get it right - as we have now palettes corresponding to the dark themes - just a checkbox "Apply suitable palette colors" under the wallpaper checkbox would do.

[stefonarch]

@tsujan Any thought about implementing this checkbox of above for 1.3?

[tsujan]

Any thought about implementing this checkbox of above for 1.3?

It could be done.

To me, porting LXQt to Qt6 has priority.