feat: SuggestedBounds event

winit-core/src/event.rs

@@ -368,6 +368,13 @@ pub enum WindowEvent {
         surface_size_writer: SurfaceSizeWriter,
     },
 
+    /// The suggested bounds of the window's surface has changed.
+    ///
+    /// Contains the new bounds of the surface
+    ///
+    /// - **iOS / Android / Web / Orbital / Windows:** Unsupported.
+    SuggestedBounds(Option<PhysicalSize<u32>>),
+
     /// The system window theme has changed.
     ///
     /// Applications might wish to react to this to change the theme of the content of the window

winit-wayland/src/event_loop/mod.rs

@@ -379,6 +379,22 @@ impl EventLoop {
                 }
             }
 
+            if compositor_update.suggested_bounds {
+                let suggested_bounds = self.with_state(|state| {
+                    let windows = state.windows.get_mut();
+                    let window = windows.get(&window_id).unwrap().lock().unwrap();
+
+                    window
+                        .last_configure
+                        .as_ref()
+                        .and_then(|c| c.suggested_bounds)
+                        .map(|b| dpi::PhysicalSize::new(b.0, b.1))
+                        .clone()
+                });
+                let event = WindowEvent::SuggestedBounds(suggested_bounds);
+                app.window_event(&self.active_event_loop, window_id, event);
+            }
+
             // NOTE: Rescale changed the physical size which winit operates in, thus we should
             // resize.
             if compositor_update.resized || compositor_update.scale_changed {

winit-wayland/src/state.rs

@@ -301,15 +301,20 @@ impl WindowHandler for WinitState {
             self.window_compositor_updates.len() - 1
         };
 
-        // Populate the configure to the window.
-        self.window_compositor_updates[pos].resized |= self
+        let mut winit_window = self
             .windows
             .get_mut()
             .get_mut(&window_id)
             .expect("got configure for dead window.")
             .lock()
-            .unwrap()
-            .configure(configure, &self.shm, &self.subcompositor_state);
+            .unwrap();
+        // Populate the configure to the window.
+
+        self.window_compositor_updates[pos].suggested_bounds |= configure.suggested_bounds
+            != winit_window.last_configure.as_ref().and_then(|last| last.suggested_bounds);
+
+        self.window_compositor_updates[pos].resized |=
+            winit_window.configure(configure, &self.shm, &self.subcompositor_state);
 
         // NOTE: configure demands wl_surface::commit, however winit doesn't commit on behalf of the
         // users, since it can break a lot of things, thus it'll ask users to redraw instead.
@@ -437,11 +442,20 @@ pub struct WindowCompositorUpdate {
 
     /// Close the window.
     pub close_window: bool,
+
+    /// New suggested bounds.
+    pub suggested_bounds: bool,
 }
 
 impl WindowCompositorUpdate {
     fn new(window_id: WindowId) -> Self {
-        Self { window_id, resized: false, scale_changed: false, close_window: false }
+        Self {
+            window_id,
+            resized: false,
+            scale_changed: false,
+            close_window: false,
+            suggested_bounds: false,
+        }
     }
 }