Rework theme API

This commit adds support for theming on macOS and
also unifies the system theme handling across platforms.

src/platform_impl/linux/mod.rs

@@ -31,8 +31,6 @@ pub use self::x11::XNotSupported;
 use self::x11::{ffi::XVisualInfo, util::WindowType as XWindowType, XConnection, XError};
 #[cfg(feature = "x11")]
 use crate::platform::x11::XlibErrorHook;
-#[cfg(feature = "wayland")]
-use crate::window::Theme;
 use crate::{
     dpi::{PhysicalPosition, PhysicalSize, Position, Size},
     error::{ExternalError, NotSupportedError, OsError as RootOsError},
@@ -41,7 +39,7 @@ use crate::{
         ControlFlow, DeviceEventFilter, EventLoopClosed, EventLoopWindowTarget as RootELW,
     },
     icon::Icon,
-    window::{CursorGrabMode, CursorIcon, UserAttentionType, WindowAttributes},
+    window::{CursorGrabMode, CursorIcon, Theme, UserAttentionType, WindowAttributes},
 };
 
 pub(crate) use crate::icon::RgbaIcon as PlatformIcon;
@@ -104,8 +102,6 @@ pub struct PlatformSpecificWindowBuilderAttributes {
     pub x11_window_types: Vec<XWindowType>,
     #[cfg(feature = "x11")]
     pub gtk_theme_variant: Option<String>,
-    #[cfg(feature = "wayland")]
-    pub csd_theme: Option<Theme>,
 }
 
 impl Default for PlatformSpecificWindowBuilderAttributes {
@@ -126,8 +122,6 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
             x11_window_types: vec![XWindowType::Normal],
             #[cfg(feature = "x11")]
             gtk_theme_variant: None,
-            #[cfg(feature = "wayland")]
-            csd_theme: None,
         }
     }
 }
@@ -590,6 +584,11 @@ impl Window {
     pub fn raw_display_handle(&self) -> RawDisplayHandle {
         x11_or_wayland!(match self; Window(window) => window.raw_display_handle())
     }
+
+    #[inline]
+    pub fn theme(&self) -> Option<Theme> {
+        x11_or_wayland!(match self; Window(window) => window.theme())
+    }
 }
 
 /// Hooks for X11 errors.

src/platform_impl/linux/wayland/window/mod.rs

@@ -170,7 +170,7 @@ impl Window {
         // Set CSD frame config from theme if specified,
         // otherwise use upstream automatic selection.
         #[cfg(feature = "sctk-adwaita")]
-        if let Some(theme) = platform_attributes.csd_theme.or_else(|| {
+        if let Some(theme) = attributes.preferred_theme.or_else(|| {
             std::env::var(WAYLAND_CSD_THEME_ENV_VAR)
                 .ok()
                 .and_then(|s| s.as_str().try_into().ok())
@@ -619,6 +619,11 @@ impl Window {
         self.window_requests.lock().unwrap().push(request);
         self.event_loop_awakener.ping();
     }
+
+    #[inline]
+    pub fn theme(&self) -> Option<Theme> {
+        None
+    }
 }
 
 impl Drop for Window {

src/platform_impl/linux/x11/window.rs

@@ -20,7 +20,7 @@ use crate::{
         Fullscreen, MonitorHandle as PlatformMonitorHandle, OsError,
         PlatformSpecificWindowBuilderAttributes, VideoMode as PlatformVideoMode,
     },
-    window::{CursorGrabMode, CursorIcon, Icon, UserAttentionType, WindowAttributes},
+    window::{CursorGrabMode, CursorIcon, Icon, Theme, UserAttentionType, WindowAttributes},
 };
 
 use super::{
@@ -1546,4 +1546,9 @@ impl UnownedWindow {
         display_handle.screen = self.screen_id;
         RawDisplayHandle::Xlib(display_handle)
     }
+
+    #[inline]
+    pub fn theme(&self) -> Option<Theme> {
+        None
+    }
 }