make scale factor available from bevy_window

crates/bevy_window/src/window.rs

@@ -46,6 +46,7 @@ pub struct Window {
     #[cfg(target_arch = "wasm32")]
     pub canvas: Option<String>,
     command_queue: Vec<WindowCommand>,
+    scale_factor: f64,
 }
 
 #[derive(Debug)]
@@ -110,6 +111,7 @@ impl Window {
             #[cfg(target_arch = "wasm32")]
             canvas: window_descriptor.canvas.clone(),
             command_queue: Vec::new(),
+            scale_factor: 1.0,
         }
     }
 
@@ -141,6 +143,16 @@ impl Window {
         self.height = height;
     }
 
+    #[doc(hidden)]
+    pub fn update_scale_factor_from_backend(&mut self, scale_factor: f64) {
+        self.scale_factor = scale_factor;
+    }
+
+    #[inline]
+    pub fn scale_factor(&self) -> f64 {
+        self.scale_factor
+    }
+
     #[inline]
     pub fn title(&self) -> &str {
         &self.title

crates/bevy_winit/src/lib.rs

@@ -304,6 +304,7 @@ pub fn winit_runner(mut app: App) {
                     let window = windows.get_mut(window_id).unwrap();
                     let size = new_inner_size.to_logical(scale_factor);
                     window.update_resolution_from_backend(size.width, size.height);
+                    window.update_scale_factor_from_backend(scale_factor);
                 }
                 _ => {}
             },
@@ -344,8 +345,8 @@ fn handle_create_window_events(
     let create_window_events = resources.get::<Events<CreateWindow>>().unwrap();
     let mut window_created_events = resources.get_mut::<Events<WindowCreated>>().unwrap();
     for create_window_event in create_window_event_reader.iter(&create_window_events) {
-        let window = Window::new(create_window_event.id, &create_window_event.descriptor);
-        winit_windows.create_window(event_loop, &window);
+        let mut window = Window::new(create_window_event.id, &create_window_event.descriptor);
+        winit_windows.create_window(event_loop, &mut window);
         let window_id = window.id();
         windows.add(window);
         window_created_events.send(WindowCreated { id: window_id });

crates/bevy_winit/src/winit_windows.rs

@@ -12,7 +12,7 @@ impl WinitWindows {
     pub fn create_window(
         &mut self,
         event_loop: &winit::event_loop::EventLoopWindowTarget<()>,
-        window: &Window,
+        window: &mut Window,
     ) {
         #[cfg(target_os = "windows")]
         let mut winit_window_builder = {
@@ -100,6 +100,8 @@ impl WinitWindows {
             }
         }
 
+        window.update_scale_factor_from_backend(winit_window.scale_factor());
+
         self.windows.insert(winit_window.id(), winit_window);
     }