AppKit/UIKit: Do not emit default state events upon window creation (#3912)

Do not emit redundant ScaleFactorChanged, SurfaceResized and Focused.

src/changelog/unreleased.md

@@ -161,6 +161,8 @@ changelog entry.
   - In the same spirit rename `DeviceEvent::MouseMotion` to `PointerMotion`.
   - Remove `Force::Calibrated::altitude_angle`.
 - On X11, use bottom-right corner for IME hotspot in `Window::set_ime_cursor_area`.
+- On macOS and iOS, no longer emit `ScaleFactorChanged` upon window creation.
+- On macOS, no longer emit `Focused` upon window creation.
 
 ### Removed
 

src/event.rs

@@ -153,6 +153,9 @@ pub enum WindowEvent {
     /// Contains the new dimensions of the surface (can also be retrieved with
     /// [`Window::surface_size`]).
     ///
+    /// This event will not necessarily be emitted upon window creation, query
+    /// [`Window::surface_size`] if you need to determine the surface's initial size.
+    ///
     /// [`Window::surface_size`]: crate::window::Window::surface_size
     SurfaceResized(PhysicalSize<u32>),
 
@@ -193,6 +196,9 @@ pub enum WindowEvent {
     /// The window gained or lost focus.
     ///
     /// The parameter is true if the window has gained focus, and false if it has lost focus.
+    ///
+    /// Windows are unfocused upon creation, but will usually be focused by the system soon
+    /// afterwards.
     Focused(bool),
 
     /// An event from the keyboard has been received.
@@ -420,7 +426,12 @@ pub enum WindowEvent {
     /// To update the window size, use the provided [`SurfaceSizeWriter`] handle. By default, the
     /// window is resized to the value suggested by the OS, but it can be changed to any value.
     ///
+    /// This event will not necessarily be emitted upon window creation, query
+    /// [`Window::scale_factor`] if you need to determine the window's initial scale factor.
+    ///
     /// For more information about DPI in general, see the [`dpi`] crate.
+    ///
+    /// [`Window::scale_factor`]: crate::window::Window::scale_factor
     ScaleFactorChanged {
         scale_factor: f64,
         /// Handle to update surface size during scale changes.

src/platform_impl/apple/appkit/window_delegate.rs

@@ -765,12 +765,6 @@ impl WindowDelegate {
         });
         let delegate: Retained<WindowDelegate> = unsafe { msg_send_id![super(delegate), init] };
 
-        if scale_factor != 1.0 {
-            let delegate = delegate.clone();
-            RunLoop::main(mtm).queue_closure(move || {
-                delegate.handle_scale_factor_changed(scale_factor);
-            });
-        }
         window.setDelegate(Some(ProtocolObject::from_ref(&*delegate)));
 
         // Listen for theme change event.
@@ -801,10 +795,6 @@ impl WindowDelegate {
 
         delegate.set_cursor(attrs.cursor);
 
-        // XXX Send `Focused(false)` right after creating the window delegate, so we won't
-        // obscure the real focused events on the startup.
-        delegate.queue_event(WindowEvent::Focused(false));
-
         // Set fullscreen mode after we setup everything
         delegate.set_fullscreen(attrs.fullscreen.map(Into::into));
 

src/platform_impl/apple/uikit/window.rs

@@ -517,30 +517,6 @@ impl Window {
         let window = WinitUIWindow::new(mtm, &window_attributes, frame, &view_controller);
         window.makeKeyAndVisible();
 
-        // Like the Windows and macOS backends, we send a `ScaleFactorChanged` and `SurfaceResized`
-        // event on window creation if the DPI factor != 1.0
-        let scale_factor = view.contentScaleFactor();
-        let scale_factor = scale_factor as f64;
-        if scale_factor != 1.0 {
-            let frame = view.frame();
-            let size =
-                LogicalSize { width: frame.size.width as f64, height: frame.size.height as f64 };
-            app_state::handle_nonuser_events(
-                mtm,
-                std::iter::once(EventWrapper::ScaleFactorChanged(app_state::ScaleFactorChanged {
-                    window: window.clone(),
-                    scale_factor,
-                    suggested_size: size.to_physical(scale_factor),
-                }))
-                .chain(std::iter::once(EventWrapper::StaticEvent(
-                    Event::WindowEvent {
-                        window_id: window.id(),
-                        event: WindowEvent::SurfaceResized(size.to_physical(scale_factor)),
-                    },
-                ))),
-            );
-        }
-
         let inner = Inner { window, view_controller, view, gl_or_metal_backed };
         Ok(Window { inner: MainThreadBound::new(inner, mtm) })
     }