On Windows and MacOS, add Window::has_focus

src/platform_impl/web/event_loop/window_target.rs

@@ -56,6 +56,7 @@ impl<T> EventLoopWindowTarget<T> {
         canvas: &Rc<RefCell<backend::Canvas>>,
         id: WindowId,
         prevent_default: bool,
+        has_focus: Rc<RefCell<bool>>,
     ) {
         self.runner.add_canvas(RootWindowId(id), canvas);
         let mut canvas = canvas.borrow_mut();
@@ -65,7 +66,9 @@ impl<T> EventLoopWindowTarget<T> {
         canvas.on_touch_end(prevent_default);
 
         let runner = self.runner.clone();
+        let has_focus_clone = has_focus.clone();
         canvas.on_blur(move || {
+            *has_focus_clone.borrow_mut() = false;
             runner.send_event(Event::WindowEvent {
                 window_id: RootWindowId(id),
                 event: WindowEvent::Focused(false),
@@ -73,7 +76,9 @@ impl<T> EventLoopWindowTarget<T> {
         });
 
         let runner = self.runner.clone();
+        let has_focus_clone = has_focus.clone();
         canvas.on_focus(move || {
+            *has_focus_clone.borrow_mut() = true;
             runner.send_event(Event::WindowEvent {
                 window_id: RootWindowId(id),
                 event: WindowEvent::Focused(true),
@@ -191,6 +196,8 @@ impl<T> EventLoopWindowTarget<T> {
         let runner_touch = self.runner.clone();
         canvas.on_mouse_press(
             move |pointer_id, position, button, modifiers| {
+                *has_focus.borrow_mut() = true;
+
                 // A mouse down event may come in without any prior CursorMoved events,
                 // therefore we should send a CursorMoved event to make sure that the
                 // user code has the correct cursor position.

src/platform_impl/web/window.rs

@@ -23,6 +23,7 @@ pub struct Window {
     register_redraw_request: Box<dyn Fn()>,
     resize_notify_fn: Box<dyn Fn(PhysicalSize<u32>)>,
     destroy_fn: Option<Box<dyn FnOnce()>>,
+    has_focus: Rc<RefCell<bool>>,
 }
 
 impl Window {
@@ -42,7 +43,8 @@ impl Window {
 
         let register_redraw_request = Box::new(move || runner.request_redraw(RootWI(id)));
 
-        target.register(&canvas, id, prevent_default);
+        let has_focus = Rc::new(RefCell::new(false));
+        target.register(&canvas, id, prevent_default, has_focus.clone());
 
         let runner = target.runner.clone();
         let resize_notify_fn = Box::new(move |new_size| {
@@ -62,6 +64,7 @@ impl Window {
             register_redraw_request,
             resize_notify_fn,
             destroy_fn: Some(destroy_fn),
+            has_focus,
         };
 
         backend::set_canvas_size(
@@ -399,6 +402,10 @@ impl Window {
     }
 
     #[inline]
+    pub fn has_focus(&self) -> bool {
+        *self.has_focus.borrow()
+    }
+
     pub fn title(&self) -> String {
         String::new()
     }