Avoid double borrow panic when resizing windows

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

gpui/src/app.rs

@@ -1217,16 +1217,8 @@ impl MutableAppContext {
 
         {
             let mut app = self.upgrade();
-            let presenter = presenter.clone();
-            window.on_resize(Box::new(move |window| {
-                app.update(|cx| {
-                    let scene = presenter.borrow_mut().build_scene(
-                        window.size(),
-                        window.scale_factor(),
-                        cx,
-                    );
-                    window.present_scene(scene);
-                })
+            window.on_resize(Box::new(move || {
+                app.update(|cx| cx.resize_window(window_id))
             }));
         }
 
@@ -1391,6 +1383,13 @@ impl MutableAppContext {
                         Effect::Focus { window_id, view_id } => {
                             self.focus(window_id, view_id);
                         }
+                        Effect::ResizeWindow { window_id } => {
+                            if let Some(window) = self.cx.windows.get_mut(&window_id) {
+                                window
+                                    .invalidation
+                                    .get_or_insert(WindowInvalidation::default());
+                            }
+                        }
                         Effect::RefreshWindows => {
                             refreshing = true;
                         }
@@ -1439,6 +1438,11 @@ impl MutableAppContext {
         }
     }
 
+    fn resize_window(&mut self, window_id: usize) {
+        self.pending_effects
+            .push_back(Effect::ResizeWindow { window_id });
+    }
+
     pub fn refresh_windows(&mut self) {
         self.pending_effects.push_back(Effect::RefreshWindows);
     }
@@ -1794,6 +1798,9 @@ pub enum Effect {
         window_id: usize,
         view_id: usize,
     },
+    ResizeWindow {
+        window_id: usize,
+    },
     RefreshWindows,
 }
 
@@ -1818,6 +1825,10 @@ impl Debug for Effect {
                 .field("window_id", window_id)
                 .field("view_id", view_id)
                 .finish(),
+            Effect::ResizeWindow { window_id } => f
+                .debug_struct("Effect::RefreshWindow")
+                .field("window_id", window_id)
+                .finish(),
             Effect::RefreshWindows => f.debug_struct("Effect::FullViewRefresh").finish(),
         }
     }

gpui/src/platform.rs

@@ -80,7 +80,7 @@ pub trait Dispatcher: Send + Sync {
 pub trait Window: WindowContext {
     fn as_any_mut(&mut self) -> &mut dyn Any;
     fn on_event(&mut self, callback: Box<dyn FnMut(Event)>);
-    fn on_resize(&mut self, callback: Box<dyn FnMut(&mut dyn WindowContext)>);
+    fn on_resize(&mut self, callback: Box<dyn FnMut()>);
     fn on_close(&mut self, callback: Box<dyn FnOnce()>);
     fn prompt(
         &self,

gpui/src/platform/mac/window.rs

@@ -130,7 +130,7 @@ struct WindowState {
     id: usize,
     native_window: id,
     event_callback: Option<Box<dyn FnMut(Event)>>,
-    resize_callback: Option<Box<dyn FnMut(&mut dyn platform::WindowContext)>>,
+    resize_callback: Option<Box<dyn FnMut()>>,
     close_callback: Option<Box<dyn FnOnce()>>,
     synthetic_drag_counter: usize,
     executor: Rc<executor::Foreground>,
@@ -280,7 +280,7 @@ impl platform::Window for Window {
         self.0.as_ref().borrow_mut().event_callback = Some(callback);
     }
 
-    fn on_resize(&mut self, callback: Box<dyn FnMut(&mut dyn platform::WindowContext)>) {
+    fn on_resize(&mut self, callback: Box<dyn FnMut()>) {
         self.0.as_ref().borrow_mut().resize_callback = Some(callback);
     }
 
@@ -489,24 +489,24 @@ extern "C" fn make_backing_layer(this: &Object, _: Sel) -> id {
 
 extern "C" fn view_did_change_backing_properties(this: &Object, _: Sel) {
     let window_state = unsafe { get_window_state(this) };
-    let mut window_state = window_state.as_ref().borrow_mut();
+    let mut window_state_borrow = window_state.as_ref().borrow_mut();
 
     unsafe {
-        let _: () =
-            msg_send![window_state.layer, setContentsScale: window_state.scale_factor() as f64];
+        let _: () = msg_send![window_state_borrow.layer, setContentsScale: window_state_borrow.scale_factor() as f64];
     }
 
-    if let Some(mut callback) = window_state.resize_callback.take() {
-        callback(&mut *window_state);
-        window_state.resize_callback = Some(callback);
+    if let Some(mut callback) = window_state_borrow.resize_callback.take() {
+        drop(window_state_borrow);
+        callback();
+        window_state.as_ref().borrow_mut().resize_callback = Some(callback);
     };
 }
 
 extern "C" fn set_frame_size(this: &Object, _: Sel, size: NSSize) {
     let window_state = unsafe { get_window_state(this) };
-    let mut window_state = window_state.as_ref().borrow_mut();
+    let mut window_state_borrow = window_state.as_ref().borrow_mut();
 
-    if window_state.size() == vec2f(size.width as f32, size.height as f32) {
+    if window_state_borrow.size() == vec2f(size.width as f32, size.height as f32) {
         return;
     }
 
@@ -514,19 +514,20 @@ extern "C" fn set_frame_size(this: &Object, _: Sel, size: NSSize) {
         let _: () = msg_send![super(this, class!(NSView)), setFrameSize: size];
     }
 
-    let scale_factor = window_state.scale_factor() as f64;
+    let scale_factor = window_state_borrow.scale_factor() as f64;
     let drawable_size: NSSize = NSSize {
         width: size.width * scale_factor,
         height: size.height * scale_factor,
     };
 
     unsafe {
-        let _: () = msg_send![window_state.layer, setDrawableSize: drawable_size];
+        let _: () = msg_send![window_state_borrow.layer, setDrawableSize: drawable_size];
     }
 
-    if let Some(mut callback) = window_state.resize_callback.take() {
-        callback(&mut *window_state);
-        window_state.resize_callback = Some(callback);
+    if let Some(mut callback) = window_state_borrow.resize_callback.take() {
+        drop(window_state_borrow);
+        callback();
+        window_state.borrow_mut().resize_callback = Some(callback);
     };
 }
 

gpui/src/platform/test.rs

@@ -29,7 +29,7 @@ pub struct Window {
     scale_factor: f32,
     current_scene: Option<crate::Scene>,
     event_handlers: Vec<Box<dyn FnMut(super::Event)>>,
-    resize_handlers: Vec<Box<dyn FnMut(&mut dyn super::WindowContext)>>,
+    resize_handlers: Vec<Box<dyn FnMut()>>,
     close_handlers: Vec<Box<dyn FnOnce()>>,
     pub(crate) last_prompt: RefCell<Option<Box<dyn FnOnce(usize)>>>,
 }
@@ -189,7 +189,7 @@ impl super::Window for Window {
         self.event_handlers.push(callback);
     }
 
-    fn on_resize(&mut self, callback: Box<dyn FnMut(&mut dyn super::WindowContext)>) {
+    fn on_resize(&mut self, callback: Box<dyn FnMut()>) {
         self.resize_handlers.push(callback);
     }