macOS: Don't change fullscreen state during fullscreen transition (#1331)

* Register windowWillExitFullScreen

* On macOS: Do not toggle fullscreen during fullscreen transition

* Add CHANGELOG

Co-authored-by: Freya Gentz <zegentzy@protonmail.com>

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- On macOS, fix error when `set_fullscreen` is called during fullscreen transition.
 - On all platforms except mobile and WASM, implement `Window::set_minimized`.
 - On X11, fix `CursorEntered` event being generated for non-winit windows.
 - On macOS, fix crash when starting maximized without decorations.

src/platform_impl/macos/window.rs

@@ -243,6 +243,13 @@ lazy_static! {
 pub struct SharedState {
     pub resizable: bool,
     pub fullscreen: Option<Fullscreen>,
+    // This is true between windowWillEnterFullScreen and windowDidEnterFullScreen
+    // or windowWillExitFullScreen and windowDidExitFullScreen.
+    // We must not toggle fullscreen when this is true.
+    pub in_fullscreen_transition: bool,
+    // If it is attempted to toggle fullscreen when in_fullscreen_transition is true,
+    // Set target_fullscreen and do after fullscreen transition is end.
+    pub target_fullscreen: Option<Option<Fullscreen>>,
     pub maximized: bool,
     pub standard_frame: Option<NSRect>,
     is_simple_fullscreen: bool,
@@ -661,11 +668,18 @@ impl UnownedWindow {
     #[inline]
     pub fn set_fullscreen(&self, fullscreen: Option<Fullscreen>) {
         trace!("Locked shared state in `set_fullscreen`");
-        let shared_state_lock = self.shared_state.lock().unwrap();
+        let mut shared_state_lock = self.shared_state.lock().unwrap();
         if shared_state_lock.is_simple_fullscreen {
             trace!("Unlocked shared state in `set_fullscreen`");
             return;
         }
+        if shared_state_lock.in_fullscreen_transition {
+            // We can't set fullscreen here.
+            // Set fullscreen after transition.
+            shared_state_lock.target_fullscreen = Some(fullscreen);
+            trace!("Unlocked shared state in `set_fullscreen`");
+            return;
+        }
         let old_fullscreen = shared_state_lock.fullscreen.clone();
         if fullscreen == old_fullscreen {
             trace!("Unlocked shared state in `set_fullscreen`");

src/platform_impl/macos/window_delegate.rs

@@ -195,6 +195,10 @@ lazy_static! {
             sel!(windowDidExitFullScreen:),
             window_did_exit_fullscreen as extern "C" fn(&Object, Sel, id),
         );
+        decl.add_method(
+            sel!(windowWillExitFullScreen:),
+            window_will_exit_fullscreen as extern "C" fn(&Object, Sel, id),
+        );
         decl.add_method(
             sel!(windowDidFailToEnterFullScreen:),
             window_did_fail_to_enter_fullscreen as extern "C" fn(&Object, Sel, id),
@@ -419,13 +423,27 @@ extern "C" fn window_will_enter_fullscreen(this: &Object, _: Sel, _: id) {
                     shared_state.fullscreen = Some(Fullscreen::Borderless(window.current_monitor()))
                 }
             }
-
+            shared_state.in_fullscreen_transition = true;
             trace!("Unlocked shared state in `window_will_enter_fullscreen`");
         })
     });
     trace!("Completed `windowWillEnterFullscreen:`");
 }
 
+/// Invoked when before exit fullscreen
+extern "C" fn window_will_exit_fullscreen(this: &Object, _: Sel, _: id) {
+    trace!("Triggered `windowWillExitFullScreen:`");
+    with_state(this, |state| {
+        state.with_window(|window| {
+            trace!("Locked shared state in `window_will_exit_fullscreen`");
+            let mut shared_state = window.shared_state.lock().unwrap();
+            shared_state.in_fullscreen_transition = true;
+            trace!("Unlocked shared state in `window_will_exit_fullscreen`");
+        });
+    });
+    trace!("Completed `windowWillExitFullScreen:`");
+}
+
 extern "C" fn window_will_use_fullscreen_presentation_options(
     _this: &Object,
     _: Sel,
@@ -451,6 +469,17 @@ extern "C" fn window_did_enter_fullscreen(this: &Object, _: Sel, _: id) {
     trace!("Triggered `windowDidEnterFullscreen:`");
     with_state(this, |state| {
         state.initial_fullscreen = false;
+        state.with_window(|window| {
+            trace!("Locked shared state in `window_did_enter_fullscreen`");
+            let mut shared_state = window.shared_state.lock().unwrap();
+            shared_state.in_fullscreen_transition = false;
+            let target_fullscreen = shared_state.target_fullscreen.take();
+            trace!("Unlocked shared state in `window_did_enter_fullscreen`");
+            drop(shared_state);
+            if let Some(target_fullscreen) = target_fullscreen {
+                window.set_fullscreen(target_fullscreen);
+            }
+        });
     });
     trace!("Completed `windowDidEnterFullscreen:`");
 }
@@ -461,6 +490,15 @@ extern "C" fn window_did_exit_fullscreen(this: &Object, _: Sel, _: id) {
     with_state(this, |state| {
         state.with_window(|window| {
             window.restore_state_from_fullscreen();
+            trace!("Locked shared state in `window_did_exit_fullscreen`");
+            let mut shared_state = window.shared_state.lock().unwrap();
+            shared_state.in_fullscreen_transition = false;
+            let target_fullscreen = shared_state.target_fullscreen.take();
+            trace!("Unlocked shared state in `window_did_exit_fullscreen`");
+            drop(shared_state);
+            if let Some(target_fullscreen) = target_fullscreen {
+                window.set_fullscreen(target_fullscreen);
+            }
         })
     });
     trace!("Completed `windowDidExitFullscreen:`");
@@ -485,6 +523,13 @@ extern "C" fn window_did_exit_fullscreen(this: &Object, _: Sel, _: id) {
 extern "C" fn window_did_fail_to_enter_fullscreen(this: &Object, _: Sel, _: id) {
     trace!("Triggered `windowDidFailToEnterFullscreen:`");
     with_state(this, |state| {
+        state.with_window(|window| {
+            trace!("Locked shared state in `window_did_fail_to_enter_fullscreen`");
+            let mut shared_state = window.shared_state.lock().unwrap();
+            shared_state.in_fullscreen_transition = false;
+            shared_state.target_fullscreen = None;
+            trace!("Unlocked shared state in `window_did_fail_to_enter_fullscreen`");
+        });
         if state.initial_fullscreen {
             let _: () = unsafe {
                 msg_send![*state.ns_window,