Rework theme API

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

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,
-    NSCursor, NSFilenamesPboardType, NSRequestUserAttentionType, NSResponder, NSScreen, NSWindow,
-    NSWindowButton, NSWindowLevel, NSWindowStyleMask, NSWindowTitleVisibility,
+    NSApp, NSAppKitVersion, NSAppearance, NSApplicationPresentationOptions, NSBackingStoreType,
+    NSColor, NSCursor, NSFilenamesPboardType, NSRequestUserAttentionType, NSResponder, NSScreen,
+    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));
+            }
+        }
     }
 );