Rework theme API

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

CHANGELOG.md

@@ -22,6 +22,10 @@ And please only add new entries to the top of this list, right below the `# Unre
 - On Wayland, a new `wayland-csd-adwaita-crossfont` feature was added to use `crossfont` instead of `ab_glyph` for decorations.
 - On Wayland, if not otherwise specified use upstream automatic CSD theme selection.
 - On X11, added `WindowExtX11::with_parent` to create child windows.
+- Added support for `WindowBuilder::with_theme` and `Window::theme` to support per-window dark/light/system theme configuration on macos, windows and wayland.
+- On macOS, added support for `WindowEvent::ThemeChanged`.
+- **Breaking:** Removed `WindowBuilderExtWindows::with_theme` and `WindowBuilderExtWayland::with_wayland_csd_theme` in favour of `WindowBuilder::with_theme`.
+- **Breaking:** Removed `WindowExtWindows::theme` in favour of `Window::theme`.
 
 # 0.27.4
 

FEATURES.md

@@ -130,6 +130,7 @@ If your PR makes notable changes to Winit's features, please update this section
 * Hidden titlebar buttons
 * Full-size content view
 * Accepts first mouse
+* Set a preferred theme and get current theme.
 
 ### Unix
 * Window urgency

examples/theme.rs

@@ -0,0 +1,40 @@
+#![allow(clippy::single_match)]
+
+use simple_logger::SimpleLogger;
+use winit::{
+    event::{Event, WindowEvent},
+    event_loop::{ControlFlow, EventLoop},
+    window::{Theme, WindowBuilder},
+};
+
+fn main() {
+    SimpleLogger::new().init().unwrap();
+    let event_loop = EventLoop::new();
+
+    let window = WindowBuilder::new()
+        .with_title("A fantastic window!")
+        .with_theme(Some(Theme::Dark))
+        .build(&event_loop)
+        .unwrap();
+
+    println!("Initial theme: {:?}", window.theme());
+
+    event_loop.run(move |event, _, control_flow| {
+        *control_flow = ControlFlow::Wait;
+
+        match event {
+            Event::WindowEvent {
+                event: WindowEvent::CloseRequested,
+                ..
+            } => *control_flow = ControlFlow::Exit,
+            Event::WindowEvent {
+                event: WindowEvent::ThemeChanged(theme),
+                window_id,
+                ..
+            } if window_id == window.id() => {
+                println!("Theme is changed: {:?}", theme)
+            }
+            _ => (),
+        }
+    });
+}

src/event.rs

@@ -504,7 +504,7 @@ pub enum WindowEvent<'a> {
     ///
     /// ## Platform-specific
     ///
-    /// At the moment this is only supported on Windows.
+    /// - **iOS / Android / X11 / Wayland:** Unsupported.
     ThemeChanged(Theme),
 
     /// The window has been occluded (completely hidden from view).

src/platform/wayland.rs

@@ -138,14 +138,6 @@ pub trait WindowBuilderExtWayland {
     /// For details about application ID conventions, see the
     /// [Desktop Entry Spec](https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#desktop-file-id)
     fn with_name(self, general: impl Into<String>, instance: impl Into<String>) -> Self;
-
-    /// Build window with certain decoration [`Theme`]
-    ///
-    /// You can also use `WINIT_WAYLAND_CSD_THEME` env variable to set the theme.
-    /// Possible values for env variable are: "dark" and light".
-    ///
-    /// When unspecified a theme is automatically selected.
-    fn with_wayland_csd_theme(self, theme: Theme) -> Self;
 }
 
 impl WindowBuilderExtWayland for WindowBuilder {
@@ -154,12 +146,6 @@ impl WindowBuilderExtWayland for WindowBuilder {
         self.platform_specific.name = Some(ApplicationName::new(general.into(), instance.into()));
         self
     }
-
-    #[inline]
-    fn with_wayland_csd_theme(mut self, theme: Theme) -> Self {
-        self.platform_specific.csd_theme = Some(theme);
-        self
-    }
 }
 
 /// Additional methods on `MonitorHandle` that are specific to Wayland.

src/platform/windows.rs

@@ -6,7 +6,7 @@ use crate::{
     event_loop::EventLoopBuilder,
     monitor::MonitorHandle,
     platform_impl::{Parent, WinIcon},
-    window::{BadIcon, Icon, Theme, Window, WindowBuilder},
+    window::{BadIcon, Icon, Window, WindowBuilder},
 };
 
 /// Window Handle type used by Win32 API
@@ -136,9 +136,6 @@ pub trait WindowExtWindows {
     /// This sets `ICON_BIG`. A good ceiling here is 256x256.
     fn set_taskbar_icon(&self, taskbar_icon: Option<Icon>);
 
-    /// Returns the current window theme.
-    fn theme(&self) -> Theme;
-
     /// Whether to show or hide the window icon in the taskbar.
     fn set_skip_taskbar(&self, skip: bool);
 
@@ -169,11 +166,6 @@ impl WindowExtWindows for Window {
         self.window.set_taskbar_icon(taskbar_icon)
     }
 
-    #[inline]
-    fn theme(&self) -> Theme {
-        self.window.theme()
-    }
-
     #[inline]
     fn set_skip_taskbar(&self, skip: bool) {
         self.window.set_skip_taskbar(skip)
@@ -232,9 +224,6 @@ pub trait WindowBuilderExtWindows {
     /// See <https://docs.microsoft.com/en-us/windows/win32/api/objbase/nf-objbase-coinitialize#remarks> for more information.
     fn with_drag_and_drop(self, flag: bool) -> WindowBuilder;
 
-    /// Forces a theme or uses the system settings if `None` was provided.
-    fn with_theme(self, theme: Option<Theme>) -> WindowBuilder;
-
     /// Whether show or hide the window icon in the taskbar.
     fn with_skip_taskbar(self, skip: bool) -> WindowBuilder;
 
@@ -282,12 +271,6 @@ impl WindowBuilderExtWindows for WindowBuilder {
         self
     }
 
-    #[inline]
-    fn with_theme(mut self, theme: Option<Theme>) -> WindowBuilder {
-        self.platform_specific.preferred_theme = theme;
-        self
-    }
-
     #[inline]
     fn with_skip_taskbar(mut self, skip: bool) -> WindowBuilder {
         self.platform_specific.skip_taskbar = skip;

src/platform_impl/android/mod.rs

@@ -24,7 +24,7 @@ use crate::{
     error,
     event::{self, VirtualKeyCode},
     event_loop::{self, ControlFlow},
-    window::{self, CursorGrabMode},
+    window::{self, CursorGrabMode, Theme},
 };
 
 static CONFIG: Lazy<RwLock<Configuration>> = Lazy::new(|| {
@@ -852,6 +852,10 @@ impl Window {
     pub fn content_rect(&self) -> Rect {
         ndk_glue::content_rect()
     }
+
+    pub fn theme(&self) -> Option<Theme> {
+        None
+    }
 }
 
 #[derive(Default, Clone, Debug)]

src/platform_impl/ios/window.rs

@@ -23,7 +23,8 @@ use crate::{
         monitor, view, EventLoopWindowTarget, Fullscreen, MonitorHandle,
     },
     window::{
-        CursorGrabMode, CursorIcon, UserAttentionType, WindowAttributes, WindowId as RootWindowId,
+        CursorGrabMode, CursorIcon, Theme, UserAttentionType, WindowAttributes,
+        WindowId as RootWindowId,
     },
 };
 
@@ -341,6 +342,11 @@ impl Inner {
     pub fn raw_display_handle(&self) -> RawDisplayHandle {
         RawDisplayHandle::UiKit(UiKitDisplayHandle::empty())
     }
+
+    pub fn theme(&self) -> Option<Theme> {
+        warn!("`Window::theme` is ignored on iOS");
+        None
+    }
 }
 
 pub struct Window {

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
+    }
 }

src/platform_impl/macos/appkit/appearance.rs

@@ -0,0 +1,29 @@
+use objc2::foundation::{NSArray, NSObject, NSString};
+use objc2::rc::{Id, Shared};
+use objc2::{extern_class, extern_methods, msg_send_id, ClassType};
+
+extern_class!(
+    #[derive(Debug, PartialEq, Eq, Hash)]
+    pub(crate) struct NSAppearance;
+
+    unsafe impl ClassType for NSAppearance {
+        type Super = NSObject;
+    }
+);
+
+type NSAppearanceName = NSString;
+
+extern_methods!(
+    unsafe impl NSAppearance {
+        pub fn appearanceNamed(name: &NSAppearanceName) -> Id<Self, Shared> {
+            unsafe { msg_send_id![Self::class(), appearanceNamed: name] }
+        }
+
+        pub fn bestMatchFromAppearancesWithNames(
+            &self,
+            appearances: &NSArray<NSAppearanceName>,
+        ) -> Id<NSAppearanceName, Shared> {
+            unsafe { msg_send_id![self, bestMatchFromAppearancesWithNames: appearances,] }
+        }
+    }
+);

src/platform_impl/macos/appkit/application.rs

@@ -4,7 +4,7 @@ use objc2::runtime::Object;
 use objc2::{extern_class, extern_methods, msg_send_id, ClassType};
 use objc2::{Encode, Encoding};
 
-use super::{NSEvent, NSMenu, NSResponder, NSWindow};
+use super::{NSAppearance, NSEvent, NSMenu, NSResponder, NSWindow};
 
 extern_class!(
     #[derive(Debug, PartialEq, Eq, Hash)]
@@ -82,6 +82,13 @@ extern_methods!(
         #[sel(setMainMenu:)]
         pub fn setMainMenu(&self, menu: &NSMenu);
 
+        pub fn effectiveAppearance(&self) -> Id<NSAppearance, Shared> {
+            unsafe { msg_send_id![self, effectiveAppearance] }
+        }
+
+        #[sel(setAppearance:)]
+        pub fn setAppearance(&self, appearance: &NSAppearance);
+
         #[sel(run)]
         pub unsafe fn run(&self);
     }

src/platform_impl/macos/appkit/mod.rs

@@ -11,6 +11,7 @@
 #![allow(clippy::enum_variant_names)]
 #![allow(non_upper_case_globals)]
 
+mod appearance;
 mod application;
 mod button;
 mod color;
@@ -28,6 +29,7 @@ mod version;
 mod view;
 mod window;
 
+pub(crate) use self::appearance::NSAppearance;
 pub(crate) use self::application::{
     NSApp, NSApplication, NSApplicationActivationPolicy, NSApplicationPresentationOptions,
     NSRequestUserAttentionType,

src/platform_impl/macos/window.rs

@@ -29,7 +29,8 @@ use crate::{
         Fullscreen, OsError,
     },
     window::{
-        CursorGrabMode, CursorIcon, UserAttentionType, WindowAttributes, WindowId as RootWindowId,
+        CursorGrabMode, CursorIcon, Theme, UserAttentionType, WindowAttributes,
+        WindowId as RootWindowId,
     },
 };
 use core_graphics::display::{CGDisplay, CGPoint};
@@ -38,12 +39,12 @@ use objc2::foundation::{
     is_main_thread, CGFloat, NSArray, NSCopying, NSObject, NSPoint, NSRect, NSSize, NSString,
 };
 use objc2::rc::{autoreleasepool, Id, Owned, Shared};
-use objc2::{declare_class, msg_send, msg_send_id, ClassType};
+use objc2::{declare_class, msg_send, msg_send_id, sel, ClassType};
 
 use super::appkit::{
-    NSApp, NSAppKitVersion, NSApplicationPresentationOptions, NSBackingStoreType, NSColor,
+    NSApp, NSAppKitVersion, NSAppearance, NSApplicationPresentationOptions, NSBackingStoreType,
-    NSCursor, NSFilenamesPboardType, NSRequestUserAttentionType, NSResponder, NSScreen, NSWindow,
+    NSColor, NSCursor, NSFilenamesPboardType, NSRequestUserAttentionType, NSResponder, NSScreen,
-    NSWindowButton, NSWindowLevel, NSWindowStyleMask, NSWindowTitleVisibility,
+    NSWindow, NSWindowButton, NSWindowLevel, NSWindowStyleMask, NSWindowTitleVisibility,
 };
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -149,6 +150,7 @@ pub struct SharedState {
     /// bar in exclusive fullscreen but want to restore the original options when
     /// transitioning back to borderless fullscreen.
     save_presentation_opts: Option<NSApplicationPresentationOptions>,
+    pub current_theme: Option<Theme>,
 }
 
 impl SharedState {
@@ -391,6 +393,18 @@ impl WinitWindow {
             unsafe { NSFilenamesPboardType }.copy()
         ]));
 
+        match attrs.preferred_theme {
+            Some(theme) => {
+                set_ns_theme(theme);
+                let mut state = this.shared_state.lock().unwrap();
+                state.current_theme = Some(theme);
+            }
+            None => {
+                let mut state = this.shared_state.lock().unwrap();
+                state.current_theme = Some(get_ns_theme());
+            }
+        }
+
         let delegate = WinitWindowDelegate::new(&this, attrs.fullscreen.is_some());
 
         // Set fullscreen mode after we setup everything
@@ -1095,6 +1109,12 @@ impl WinitWindow {
             util::set_style_mask_sync(self, current_style_mask & (!mask));
         }
     }
+
+    #[inline]
+    pub fn theme(&self) -> Option<Theme> {
+        let state = self.shared_state.lock().unwrap();
+        state.current_theme
+    }
 }
 
 impl WindowExtMacOS for WinitWindow {
@@ -1186,3 +1206,33 @@ impl WindowExtMacOS for WinitWindow {
         self.setHasShadow(has_shadow)
     }
 }
+
+pub(super) fn get_ns_theme() -> Theme {
+    let app = NSApp();
+    let has_theme: bool = unsafe { msg_send![&app, respondsToSelector: sel!(effectiveAppearance)] };
+    if !has_theme {
+        return Theme::Light;
+    }
+    let appearance = app.effectiveAppearance();
+    let name = appearance.bestMatchFromAppearancesWithNames(&NSArray::from_slice(&[
+        NSString::from_str("NSAppearanceNameAqua"),
+        NSString::from_str("NSAppearanceNameDarkAqua"),
+    ]));
+    match &*name.to_string() {
+        "NSAppearanceNameDarkAqua" => Theme::Dark,
+        _ => Theme::Light,
+    }
+}
+
+fn set_ns_theme(theme: Theme) {
+    let app = NSApp();
+    let has_theme: bool = unsafe { msg_send![&app, respondsToSelector: sel!(effectiveAppearance)] };
+    if has_theme {
+        let name = match theme {
+            Theme::Dark => NSString::from_str("NSAppearanceNameDarkAqua"),
+            Theme::Light => NSString::from_str("NSAppearanceNameAqua"),
+        };
+        let appearance = NSAppearance::appearanceNamed(&name);
+        app.setAppearance(&appearance);
+    }
+}

src/platform_impl/macos/window_delegate.rs

@@ -4,7 +4,7 @@ use objc2::declare::{Ivar, IvarDrop};
 use objc2::foundation::{NSArray, NSObject, NSString};
 use objc2::rc::{autoreleasepool, Id, Shared};
 use objc2::runtime::Object;
-use objc2::{declare_class, msg_send, msg_send_id, sel, ClassType};
+use objc2::{class, declare_class, msg_send, msg_send_id, sel, ClassType};
 
 use super::appkit::{
     NSApplicationPresentationOptions, NSFilenamesPboardType, NSPasteboard, NSWindowOcclusionState,
@@ -16,7 +16,7 @@ use crate::{
         app_state::AppState,
         event::{EventProxy, EventWrapper},
         util,
-        window::WinitWindow,
+        window::{get_ns_theme, WinitWindow},
         Fullscreen,
     },
     window::WindowId,
@@ -69,6 +69,22 @@ declare_class!(
                     this.emit_static_scale_factor_changed_event();
                 }
                 this.window.setDelegate(Some(this));
+
+                // Enable theme change event
+                let notification_center: Id<Object, Shared> =
+                    unsafe { msg_send_id![class!(NSDistributedNotificationCenter), defaultCenter] };
+                let notification_name =
+                    NSString::from_str("AppleInterfaceThemeChangedNotification");
+                let _: () = unsafe {
+                    msg_send![
+                        &notification_center,
+                        addObserver: &*this
+                        selector: sel!(effectiveAppearanceDidChange:)
+                        name: &*notification_name
+                        object: ptr::null::<Object>()
+                    ]
+                };
+
                 this
             })
         }
@@ -349,6 +365,34 @@ declare_class!(
                     .contains(NSWindowOcclusionState::NSWindowOcclusionStateVisible),
             ))
         }
+
+        // Observe theme change
+        #[sel(effectiveAppearanceDidChange:)]
+        fn effective_appearance_did_change(&self, sender: Option<&Object>) {
+            trace_scope!("Triggered `effectiveAppearanceDidChange:`");
+            unsafe {
+                msg_send![
+                    self,
+                    performSelectorOnMainThread: sel!(effectiveAppearanceDidChangedOnMainThread:),
+                    withObject: sender,
+                    waitUntilDone: false,
+                ]
+            }
+        }
+
+        #[sel(effectiveAppearanceDidChangedOnMainThread:)]
+        fn effective_appearance_did_changed_on_main_thread(&self, _: Option<&Object>) {
+            let theme = get_ns_theme();
+            let mut shared_state = self
+                .window
+                .lock_shared_state("effective_appearance_did_change");
+            let current_theme = shared_state.current_theme;
+            shared_state.current_theme = Some(theme);
+            drop(shared_state);
+            if current_theme != Some(theme) {
+                self.emit_event(WindowEvent::ThemeChanged(theme));
+            }
+        }
     }
 );
 

src/platform_impl/web/window.rs

@@ -3,7 +3,7 @@ use crate::error::{ExternalError, NotSupportedError, OsError as RootOE};
 use crate::event;
 use crate::icon::Icon;
 use crate::window::{
-    CursorGrabMode, CursorIcon, UserAttentionType, WindowAttributes, WindowId as RootWI,
+    CursorGrabMode, CursorIcon, Theme, UserAttentionType, WindowAttributes, WindowId as RootWI,
 };
 
 use raw_window_handle::{RawDisplayHandle, RawWindowHandle, WebDisplayHandle, WebWindowHandle};
@@ -373,6 +373,11 @@ impl Window {
     pub fn raw_display_handle(&self) -> RawDisplayHandle {
         RawDisplayHandle::Web(WebDisplayHandle::empty())
     }
+
+    #[inline]
+    pub fn theme(&self) -> Option<Theme> {
+        None
+    }
 }
 
 impl Drop for Window {

src/platform_impl/windows/mod.rs

@@ -19,7 +19,6 @@ pub(self) use crate::platform_impl::Fullscreen;
 
 use crate::event::DeviceId as RootDeviceId;
 use crate::icon::Icon;
-use crate::window::Theme;
 
 #[derive(Clone)]
 pub enum Parent {
@@ -35,7 +34,6 @@ pub struct PlatformSpecificWindowBuilderAttributes {
     pub taskbar_icon: Option<Icon>,
     pub no_redirection_bitmap: bool,
     pub drag_and_drop: bool,
-    pub preferred_theme: Option<Theme>,
     pub skip_taskbar: bool,
     pub decoration_shadow: bool,
 }
@@ -48,7 +46,6 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
             taskbar_icon: None,
             no_redirection_bitmap: false,
             drag_and_drop: true,
-            preferred_theme: None,
             skip_taskbar: false,
             decoration_shadow: false,
         }

src/platform_impl/windows/window.rs

@@ -694,8 +694,8 @@ impl Window {
     }
 
     #[inline]
-    pub fn theme(&self) -> Theme {
+    pub fn theme(&self) -> Option<Theme> {
-        self.window_state_lock().current_theme
+        Some(self.window_state_lock().current_theme)
     }
 
     #[inline]
@@ -781,7 +781,7 @@ impl<'a, T: 'static> InitData<'a, T> {
         // If the system theme is dark, we need to set the window theme now
         // before we update the window flags (and possibly show the
         // window for the first time).
-        let current_theme = try_theme(window, self.pl_attribs.preferred_theme);
+        let current_theme = try_theme(window, self.attributes.preferred_theme);
 
         let window_state = {
             let window_state = WindowState::new(
@@ -789,7 +789,7 @@ impl<'a, T: 'static> InitData<'a, T> {
                 self.pl_attribs.taskbar_icon.clone(),
                 scale_factor,
                 current_theme,
-                self.pl_attribs.preferred_theme,
+                self.attributes.preferred_theme,
             );
             let window_state = Arc::new(Mutex::new(window_state));
             WindowState::set_window_flags(window_state.lock().unwrap(), window, |f| {

src/window.rs

@@ -134,6 +134,7 @@ pub(crate) struct WindowAttributes {
     pub decorations: bool,
     pub always_on_top: bool,
     pub window_icon: Option<Icon>,
+    pub preferred_theme: Option<Theme>,
     pub resize_increments: Option<Size>,
 }
 
@@ -154,6 +155,7 @@ impl Default for WindowAttributes {
             decorations: true,
             always_on_top: false,
             window_icon: None,
+            preferred_theme: None,
             resize_increments: None,
         }
     }
@@ -335,6 +337,23 @@ impl WindowBuilder {
         self
     }
 
+    /// Sets a specific theme for the window.
+    ///
+    /// If `None` is provided, the window will use the system theme.
+    ///
+    /// The default is `None`.
+    ///
+    /// ## Platform-specific
+    ///
+    /// - **Wayland:** This control only CSD. You can also use `WINIT_WAYLAND_CSD_THEME` env variable to set the theme.
+    ///   Possible values for env variable are: "dark" and light".
+    /// - **iOS / Android / Web / x11:** Ignored.
+    #[inline]
+    pub fn with_theme(mut self, theme: Option<Theme>) -> Self {
+        self.window.preferred_theme = theme;
+        self
+    }
+
     /// Build window with resize increments hint.
     ///
     /// The default is `None`.
@@ -923,6 +942,16 @@ impl Window {
     pub fn request_user_attention(&self, request_type: Option<UserAttentionType>) {
         self.window.request_user_attention(request_type)
     }
+
+    /// Returns the current window theme.
+    ///
+    /// ## Platform-specific
+    ///
+    /// - **iOS / Android / Web / x11:** Unsupported.
+    #[inline]
+    pub fn theme(&self) -> Option<Theme> {
+        self.window.theme()
+    }
 }
 
 /// Cursor functions.