linux: Get the color scheme through xdg-desktop-portal (#11926)

The method has been tested on:
- Gnome 46 (Working)
- Gnome 40 (Not supported)

Tasks

- [x] Implements a draft which get and provides the user theme to
components which needs it
- [x] Implements a way to call the callback function when the theme is
updated
- [X] Cleans the code

Release notes:
- N/A

crates/gpui/src/platform/linux/wayland/window.rs

@@ -2,7 +2,7 @@ use std::any::Any;
 use std::cell::{Ref, RefCell, RefMut};
 use std::ffi::c_void;
 use std::num::NonZeroU32;
-use std::ops::Range;
+use std::ops::{Deref, Range};
 use std::ptr::NonNull;
 use std::rc::{Rc, Weak};
 use std::sync::Arc;
@@ -10,6 +10,7 @@ use std::sync::Arc;
 use blade_graphics as gpu;
 use collections::{HashMap, HashSet};
 use futures::channel::oneshot::Receiver;
+use parking_lot::Mutex;
 use raw_window_handle as rwh;
 use wayland_backend::client::ObjectId;
 use wayland_client::protocol::wl_region::WlRegion;
@@ -70,6 +71,7 @@ pub struct WaylandWindowState {
     acknowledged_first_configure: bool,
     pub surface: wl_surface::WlSurface,
     decoration: Option<zxdg_toplevel_decoration_v1::ZxdgToplevelDecorationV1>,
+    appearance: WindowAppearance,
     blur: Option<org_kde_kwin_blur::OrgKdeKwinBlur>,
     toplevel: xdg_toplevel::XdgToplevel,
     viewport: Option<wp_viewport::WpViewport>,
@@ -100,6 +102,7 @@ impl WaylandWindowState {
         xdg_surface: xdg_surface::XdgSurface,
         toplevel: xdg_toplevel::XdgToplevel,
         decoration: Option<zxdg_toplevel_decoration_v1::ZxdgToplevelDecorationV1>,
+        appearance: WindowAppearance,
         viewport: Option<wp_viewport::WpViewport>,
         client: WaylandClientStatePtr,
         globals: Globals,
@@ -158,6 +161,7 @@ impl WaylandWindowState {
             maximized: false,
             callbacks: Callbacks::default(),
             client,
+            appearance,
         }
     }
 }
@@ -215,6 +219,7 @@ impl WaylandWindow {
         globals: Globals,
         client: WaylandClientStatePtr,
         params: WindowParams,
+        appearance: WindowAppearance,
     ) -> (Self, ObjectId) {
         let surface = globals.compositor.create_surface(&globals.qh, ());
         let xdg_surface = globals
@@ -251,6 +256,7 @@ impl WaylandWindow {
                 xdg_surface,
                 toplevel,
                 decoration,
+                appearance,
                 viewport,
                 client,
                 globals,
@@ -571,6 +577,15 @@ impl WaylandWindowStatePtr {
             fun(focus);
         }
     }
+
+    pub fn set_appearance(&mut self, appearance: WindowAppearance) {
+        self.state.borrow_mut().appearance = appearance;
+
+        let mut callbacks = self.callbacks.borrow_mut();
+        if let Some(ref mut fun) = callbacks.appearance_changed {
+            (fun)()
+        }
+    }
 }
 
 impl rwh::HasWindowHandle for WaylandWindow {
@@ -618,9 +633,8 @@ impl PlatformWindow for WaylandWindow {
         self.borrow().scale
     }
 
-    // todo(linux)
     fn appearance(&self) -> WindowAppearance {
-        WindowAppearance::Light
+        self.borrow().appearance
     }
 
     // todo(linux)
@@ -777,7 +791,7 @@ impl PlatformWindow for WaylandWindow {
     }
 
     fn on_appearance_changed(&self, callback: Box<dyn FnMut()>) {
-        // todo(linux)
+        self.0.callbacks.borrow_mut().appearance_changed = Some(callback);
     }
 
     fn draw(&self, scene: &Scene) {