Add cross-platform custom decorations (titlebar-less) + platform titlebar demo + small fixes

winit-appkit/src/lib.rs

@@ -187,6 +187,12 @@ pub trait WindowExtMacOS {
 
     /// Getter for the [`WindowExtMacOS::set_unified_titlebar`].
     fn unified_titlebar(&self) -> bool;
+
+    /// Returns the height of the titlebar in logical points.
+    ///
+    /// This can be useful when drawing custom UI that needs to align with the
+    /// system titlebar.
+    fn titlebar_height(&self) -> f64;
 }
 
 impl WindowExtMacOS for dyn Window + '_ {
@@ -297,6 +303,12 @@ impl WindowExtMacOS for dyn Window + '_ {
         let window = self.cast_ref::<AppKitWindow>().unwrap();
         window.maybe_wait_on_main(|w| w.unified_titlebar())
     }
+
+    #[inline]
+    fn titlebar_height(&self) -> f64 {
+        let window = self.cast_ref::<AppKitWindow>().unwrap();
+        window.maybe_wait_on_main(|w| w.titlebar_height())
+    }
 }
 
 /// Corresponds to `NSApplicationActivationPolicy`.

winit-appkit/src/view.rs

@@ -197,7 +197,11 @@ define_class!(
         fn draw_rect(&self, _rect: NSRect) {
             trace_scope!("drawRect:");
 
-            self.ivars().app_state.handle_redraw(window_id(&self.window()));
+            let Some(window) = self.window() else {
+                return;
+            };
+
+            self.ivars().app_state.handle_redraw(window_id(&window));
 
             // This is a direct subclass of NSView, no need to call superclass' drawRect:
         }
@@ -420,7 +424,11 @@ define_class!(
             }
 
             // Send command action to user if they requested it.
-            let window_id = window_id(&self.window());
+            let Some(window) = self.window() else {
+                return;
+            };
+
+            let window_id = window_id(&window);
             self.ivars().app_state.maybe_queue_with_handler(move |app, event_loop| {
                 if let Some(handler) = app.macos_handler() {
                     handler.standard_key_binding(
@@ -525,7 +533,9 @@ define_class!(
         #[unsafe(method(insertTab:))]
         fn insert_tab(&self, _sender: Option<&AnyObject>) {
             trace_scope!("insertTab:");
-            let window = self.window();
+            let Some(window) = self.window() else {
+                return;
+            };
             if let Some(first_responder) = window.firstResponder() {
                 if *first_responder == ***self {
                     window.selectNextKeyView(Some(self))
@@ -536,7 +546,9 @@ define_class!(
         #[unsafe(method(insertBackTab:))]
         fn insert_back_tab(&self, _sender: Option<&AnyObject>) {
             trace_scope!("insertBackTab:");
-            let window = self.window();
+            let Some(window) = self.window() else {
+                return;
+            };
             if let Some(first_responder) = window.firstResponder() {
                 if *first_responder == ***self {
                     window.selectPreviousKeyView(Some(self))
@@ -818,19 +830,23 @@ impl WinitView {
         this
     }
 
-    fn window(&self) -> Retained<NSWindow> {
-        (**self).window().expect("view must be installed in a window")
+    fn window(&self) -> Option<Retained<NSWindow>> {
+        (**self).window()
     }
 
     fn queue_event(&self, event: WindowEvent) {
-        let window_id = window_id(&self.window());
+        let Some(window) = self.window() else {
+            return;
+        };
+
+        let window_id = window_id(&window);
         self.ivars().app_state.maybe_queue_with_handler(move |app, event_loop| {
             app.window_event(event_loop, window_id, event);
         });
     }
 
     fn scale_factor(&self) -> f64 {
-        self.window().backingScaleFactor() as f64
+        self.window().map(|window| window.backingScaleFactor() as f64).unwrap_or(1.0)
     }
 
     fn is_ime_enabled(&self) -> bool {

winit-appkit/src/window_delegate.rs

@@ -2029,6 +2029,14 @@ impl WindowExtMacOS for WindowDelegate {
 
         window.toolbar().is_some() && window.toolbarStyle() == NSWindowToolbarStyle::Unified
     }
+
+    fn titlebar_height(&self) -> f64 {
+        let window = self.window();
+        let frame = window.frame();
+        let content = window.contentRectForFrameRect(frame);
+
+        (frame.size.height - content.size.height).max(0.0)
+    }
 }
 
 const DEFAULT_STANDARD_FRAME: NSRect =

winit-core/src/window.rs

@@ -1388,7 +1388,10 @@ pub trait Window: AsAny + Send + Sync + fmt::Debug {
     /// the title bar. This is useful when implementing custom decorations.
     ///
     /// ## Platform-specific
-    /// **Android / iOS / macOS / Orbital / Wayland / Web / X11:** Unsupported.
+    /// - **Windows:** Supported.
+    /// - **Wayland:** Supported.
+    /// - **X11:** Supported on some window managers (via `_GTK_SHOW_WINDOW_MENU`).
+    /// - **Android / iOS / macOS / Orbital / Web:** Unsupported.
     ///
     /// [window menu]: https://en.wikipedia.org/wiki/Common_menus_in_Microsoft_Windows#System_menu
     fn show_window_menu(&self, position: Position);

winit-x11/src/atoms.rs

@@ -95,6 +95,7 @@ atom_manager! {
     None: b"None",
 
     // Miscellaneous Atoms
+    _GTK_SHOW_WINDOW_MENU,
     _GTK_THEME_VARIANT,
     _MOTIF_WM_HINTS,
     _NET_ACTIVE_WINDOW,

winit-x11/src/window.rs

@@ -2007,7 +2007,36 @@ impl UnownedWindow {
     }
 
     #[inline]
-    pub fn show_window_menu(&self, _position: Position) {}
+    pub fn show_window_menu(&self, position: Position) {
+        let atoms = self.xconn.atoms();
+        let show_menu_message = atoms[_GTK_SHOW_WINDOW_MENU];
+
+        if !util::hint_is_supported(show_menu_message) {
+            return;
+        }
+
+        let (x, y): (i32, i32) = position.to_physical::<i32>(self.scale_factor()).into();
+        let (window_x, window_y) = self.inner_position_physical();
+        let x_root = (i64::from(window_x) + i64::from(x)).max(0) as u32;
+        let y_root = (i64::from(window_y) + i64::from(y)).max(0) as u32;
+
+        let result = self.xconn.send_client_msg(
+            self.xwindow,
+            self.root,
+            show_menu_message,
+            Some(xproto::EventMask::SUBSTRUCTURE_REDIRECT | xproto::EventMask::SUBSTRUCTURE_NOTIFY),
+            [util::VIRTUAL_CORE_POINTER as u32, x_root, y_root, 0, 0],
+        );
+
+        if let Err(err) = result {
+            tracing::error!("failed to request window menu: {err}");
+            return;
+        }
+
+        if let Err(err) = self.xconn.flush_requests() {
+            tracing::error!("failed to flush window menu request: {err}");
+        }
+    }
 
     /// Resizes the window while it is being dragged.
     pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), RequestError> {