On macOS, wake up the event loop immediately when a redraw is requested. (#1812)

We allow to have RunLoop running only on the main thread. Which means if
we call Window::request_redraw() from other the thread then we have to
wait until some other event arrives on the main thread. That situation
is even worse when we have ControlFlow set to the `Wait` mode then user
will not ever render anything.

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Added `is_maximized` method to `Window`.
 - On Windows, fix bug where clicking the decoration bar would make the cursor blink.
 - On Windows, fix bug causing newly created windows to erroneously display the "wait" (spinning) cursor.
+- On macOS, wake up the event loop immediately when a redraw is requested.
 - On Windows, change the default window size (1024x768) to match the default on other desktop platforms (800x600).
 - On Windows, fix bug causing mouse capture to not be released.
 - On Windows, fix fullscreen not preserving minimized/maximized state.

src/platform_impl/macos/app_state.rs

@@ -25,7 +25,7 @@ use crate::{
     platform_impl::platform::{
         event::{EventProxy, EventWrapper},
         event_loop::{post_dummy_event, PanicInfo},
-        observer::EventLoopWaker,
+        observer::{CFRunLoopGetMain, CFRunLoopWakeUp, EventLoopWaker},
         util::{IdRef, Never},
         window::get_window_id,
     },
@@ -321,6 +321,10 @@ impl AppState {
         if !pending_redraw.contains(&window_id) {
             pending_redraw.push(window_id);
         }
+        unsafe {
+            let rl = CFRunLoopGetMain();
+            CFRunLoopWakeUp(rl);
+        }
     }
 
     pub fn queue_event(wrapper: EventWrapper) {