Try to fix window resize race conditons during RedrawRequested

winit/src/lib.rs

@@ -785,22 +785,20 @@ async fn run_instance<P>(
                         };
 
                         let physical_size = window.state.physical_size();
+                        let mut logical_size = window.state.logical_size();
 
                         if physical_size.width == 0 || physical_size.height == 0
                         {
                             continue;
                         }
 
-                        if window.viewport_version
+                        // Window was resized between redraws
-                            != window.state.viewport_version()
+                        if window.surface_size != physical_size {
-                        {
-                            let logical_size = window.state.logical_size();
-
-                            let layout_span = debug::layout(id);
                             let ui = user_interfaces
                                 .remove(&id)
                                 .expect("Remove user interface");
 
+                            let layout_span = debug::layout(id);
                             let _ = user_interfaces.insert(
                                 id,
                                 ui.relayout(logical_size, &mut window.renderer),
@@ -813,8 +811,7 @@ async fn run_instance<P>(
                                 physical_size.height,
                             );
 
-                            window.viewport_version =
+                            window.surface_size = physical_size;
-                                window.state.viewport_version();
                         }
 
                         let redraw_event = core::Event::Window(
@@ -922,6 +919,30 @@ async fn run_instance<P>(
 
                                 current_compositor = next_compositor;
                                 window = window_manager.get_mut(id).unwrap();
+
+                                // Window scale factor changed during a redraw request
+                                if logical_size != window.state.logical_size() {
+                                    logical_size = window.state.logical_size();
+
+                                    log::debug!(
+                                        "Window scale factor changed during a redraw request"
+                                    );
+
+                                    let ui = user_interfaces
+                                        .remove(&id)
+                                        .expect("Remove user interface");
+
+                                    let layout_span = debug::layout(id);
+                                    let _ = user_interfaces.insert(
+                                        id,
+                                        ui.relayout(
+                                            logical_size,
+                                            &mut window.renderer,
+                                        ),
+                                    );
+                                    layout_span.finish();
+                                }
+
                                 interface =
                                     user_interfaces.get_mut(&id).unwrap();
                             }

winit/src/window.rs

@@ -57,12 +57,11 @@ where
         system_theme: theme::Mode,
     ) -> &mut Window<P, C> {
         let state = State::new(program, id, &window, system_theme);
-        let viewport_version = state.viewport_version();
+        let surface_size = state.physical_size();
-        let physical_size = state.physical_size();
         let surface = compositor.create_surface(
             window.clone(),
-            physical_size.width,
+            surface_size.width,
-            physical_size.height,
+            surface_size.height,
         );
         let renderer = compositor.create_renderer();
 
@@ -73,9 +72,9 @@ where
             Window {
                 raw: window,
                 state,
-                viewport_version,
                 exit_on_close_request,
                 surface,
+                surface_size,
                 renderer,
                 mouse_interaction: mouse::Interaction::None,
                 redraw_at: None,
@@ -164,10 +163,10 @@ where
 {
     pub raw: Arc<winit::window::Window>,
     pub state: State<P>,
-    pub viewport_version: u64,
     pub exit_on_close_request: bool,
     pub mouse_interaction: mouse::Interaction,
     pub surface: C::Surface,
+    pub surface_size: Size<u32>,
     pub renderer: P::Renderer,
     pub redraw_at: Option<Instant>,
     preedit: Option<Preedit<P::Renderer>>,

winit/src/window/state.rs

@@ -17,7 +17,6 @@ where
     title: String,
     scale_factor: f32,
     viewport: Viewport,
-    viewport_version: u64,
     cursor_position: Option<winit::dpi::PhysicalPosition<f64>>,
     modifiers: winit::keyboard::ModifiersState,
     theme: Option<P::Theme>,
@@ -35,7 +34,6 @@ where
             .field("title", &self.title)
             .field("scale_factor", &self.scale_factor)
             .field("viewport", &self.viewport)
-            .field("viewport_version", &self.viewport_version)
             .field("cursor_position", &self.cursor_position)
             .field("style", &self.style)
             .finish()
@@ -74,7 +72,6 @@ where
             title,
             scale_factor,
             viewport,
-            viewport_version: 0,
             cursor_position: None,
             modifiers: winit::keyboard::ModifiersState::default(),
             theme,
@@ -89,13 +86,6 @@ where
         &self.viewport
     }
 
-    /// Returns the version of the [`Viewport`] of the [`State`].
-    ///
-    /// The version is incremented every time the [`Viewport`] changes.
-    pub fn viewport_version(&self) -> u64 {
-        self.viewport_version
-    }
-
     /// Returns the physical [`Size`] of the [`Viewport`] of the [`State`].
     pub fn physical_size(&self) -> Size<u32> {
         self.viewport.physical_size()
@@ -164,8 +154,6 @@ where
                     size,
                     window.scale_factor() as f32 * self.scale_factor,
                 );
-
-                self.viewport_version = self.viewport_version.wrapping_add(1);
             }
             WindowEvent::ScaleFactorChanged {
                 scale_factor: new_scale_factor,
@@ -177,8 +165,6 @@ where
                     size,
                     *new_scale_factor as f32 * self.scale_factor,
                 );
-
-                self.viewport_version = self.viewport_version.wrapping_add(1);
             }
             WindowEvent::CursorMoved { position, .. }
             | WindowEvent::Touch(Touch {
@@ -225,20 +211,14 @@ where
             self.title = new_title;
         }
 
-        // Update scale factor and size
+        // Update scale factor
         let new_scale_factor = program.scale_factor(window_id);
-        let new_size = window.inner_size();
-        let current_size = self.viewport.physical_size();
 
-        if self.scale_factor != new_scale_factor
+        if self.scale_factor != new_scale_factor {
-            || (current_size.width, current_size.height)
-                != (new_size.width, new_size.height)
-        {
             self.viewport = Viewport::with_physical_size(
-                Size::new(new_size.width, new_size.height),
+                self.viewport.physical_size(),
                 window.scale_factor() as f32 * new_scale_factor,
             );
-            self.viewport_version = self.viewport_version.wrapping_add(1);
 
             self.scale_factor = new_scale_factor;
         }