Implement ApplicationHandler::can_create|destroy_surfaces() (#3765)

src/platform_impl/apple/appkit/app_state.rs

@@ -314,9 +314,9 @@ impl ApplicationDelegate {
     /// dispatch `NewEvents(Init)` + `Resumed`
     pub fn dispatch_init_events(&self) {
         self.with_handler(|app, event_loop| app.new_events(event_loop, StartCause::Init));
-        // NB: For consistency all platforms must emit a 'resumed' event even though macOS
-        // applications don't themselves have a formal suspend/resume lifecycle.
-        self.with_handler(|app, event_loop| app.resumed(event_loop));
+        // NB: For consistency all platforms must call `can_create_surfaces` even though macOS
+        // applications don't themselves have a formal surface destroy/create lifecycle.
+        self.with_handler(|app, event_loop| app.can_create_surfaces(event_loop));
     }
 
     // Called by RunLoopObserver after finishing waiting for new events

src/platform_impl/apple/uikit/app_state.rs

@@ -496,8 +496,12 @@ pub fn did_finish_launching(mtm: MainThreadMarker) {
 
     let (windows, events) = AppState::get_mut(mtm).did_finish_launching_transition();
 
-    let events = std::iter::once(EventWrapper::StaticEvent(Event::NewEvents(StartCause::Init)))
-        .chain(events);
+    let events = [
+        EventWrapper::StaticEvent(Event::NewEvents(StartCause::Init)),
+        EventWrapper::StaticEvent(Event::CreateSurfaces),
+    ]
+    .into_iter()
+    .chain(events);
     handle_nonuser_events(mtm, events);
 
     // the above window dance hack, could possibly trigger new windows to be created.

src/platform_impl/apple/uikit/event_loop.rs

@@ -130,6 +130,7 @@ fn map_user_event<A: ApplicationHandler>(
         },
         Event::Suspended => app.suspended(window_target),
         Event::Resumed => app.resumed(window_target),
+        Event::CreateSurfaces => app.can_create_surfaces(window_target),
         Event::AboutToWait => app.about_to_wait(window_target),
         Event::LoopExiting => app.exiting(window_target),
         Event::MemoryWarning => app.memory_warning(window_target),