Change `run_app(app: &mut A)` to `run_app(app: A)` (#3721)

This allows the user more control over how they pass their application state
to Winit, and will hopefully allow `Drop` implementations on the application
handler to work in the future on all platforms.

examples/child_window.rs

@@ -86,8 +86,7 @@ fn main() -> Result<(), impl std::error::Error> {
     }
 
     let event_loop = EventLoop::new().unwrap();
-    let mut app = Application::default();
-    event_loop.run_app(&mut app)
+    event_loop.run_app(Application::default())
 }
 
 #[cfg(all(feature = "rwh_06", not(any(x11_platform, macos_platform, windows_platform))))]

examples/control_flow.rs

@@ -43,8 +43,7 @@ fn main() -> Result<(), impl std::error::Error> {
 
     let event_loop = EventLoop::new().unwrap();
 
-    let mut app = ControlFlowDemo::default();
-    event_loop.run_app(&mut app)
+    event_loop.run_app(ControlFlowDemo::default())
 }
 
 #[derive(Default)]

examples/window.rs

@@ -57,9 +57,8 @@ fn main() -> Result<(), Box<dyn Error>> {
         }
     });
 
-    let mut state = Application::new(&event_loop);
-
-    event_loop.run_app(&mut state).map_err(Into::into)
+    let app = Application::new(&event_loop);
+    Ok(event_loop.run_app(app)?)
 }
 
 /// Application state and event handling.

examples/x11_embed.rs

@@ -58,8 +58,7 @@ fn main() -> Result<(), Box<dyn Error>> {
     tracing_subscriber::fmt::init();
     let event_loop = EventLoop::new()?;
 
-    let mut app = XEmbedDemo { parent_window_id, window: None };
-    event_loop.run_app(&mut app).map_err(Into::into)
+    Ok(event_loop.run_app(XEmbedDemo { parent_window_id, window: None })?)
 }
 
 #[cfg(not(x11_platform))]

src/changelog/unreleased.md

@@ -65,6 +65,9 @@ changelog entry.
   `ApplicationHandler::resumed/suspended()` are now only emitted by iOS and Web
   and now signify actually resuming/suspending the application.
 - Rename `platform::web::*ExtWebSys` to `*ExtWeb`.
+- Change signature of `EventLoop::run_app`, `EventLoopExtPumpEvents::pump_app_events` and
+  `EventLoopExtRunOnDemand::run_app_on_demand` to accept a `impl ApplicationHandler` directly,
+  instead of requiring a `&mut` reference to it.
 
 ### Removed
 

src/event_loop.rs

@@ -241,7 +241,7 @@ impl EventLoop {
     /// [`run_app()`]: Self::run_app()
     #[inline]
     #[cfg(not(all(web_platform, target_feature = "exception-handling")))]
-    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(self, app: A) -> Result<(), EventLoopError> {
         self.event_loop.run_app(app)
     }
 

src/platform/pump_events.rs

@@ -102,7 +102,7 @@ pub trait EventLoopExtPumpEvents {
     fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        app: A,
     ) -> PumpStatus;
 }
 
@@ -110,7 +110,7 @@ impl EventLoopExtPumpEvents for EventLoop {
     fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        app: A,
     ) -> PumpStatus {
         self.event_loop.pump_app_events(timeout, app)
     }

src/platform/run_on_demand.rs

@@ -58,17 +58,11 @@ pub trait EventLoopExtRunOnDemand {
     ///
     /// [`exit()`]: ActiveEventLoop::exit()
     /// [`set_control_flow()`]: ActiveEventLoop::set_control_flow()
-    fn run_app_on_demand<A: ApplicationHandler>(
-        &mut self,
-        app: &mut A,
-    ) -> Result<(), EventLoopError>;
+    fn run_app_on_demand<A: ApplicationHandler>(&mut self, app: A) -> Result<(), EventLoopError>;
 }
 
 impl EventLoopExtRunOnDemand for EventLoop {
-    fn run_app_on_demand<A: ApplicationHandler>(
-        &mut self,
-        app: &mut A,
-    ) -> Result<(), EventLoopError> {
+    fn run_app_on_demand<A: ApplicationHandler>(&mut self, app: A) -> Result<(), EventLoopError> {
         self.event_loop.window_target().clear_exit();
         self.event_loop.run_app_on_demand(app)
     }

src/platform_impl/android/mod.rs

@@ -417,16 +417,16 @@ impl EventLoop {
         input_status
     }
 
-    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: A) -> Result<(), EventLoopError> {
         self.run_app_on_demand(app)
     }
 
     pub fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
-        app: &mut A,
+        mut app: A,
     ) -> Result<(), EventLoopError> {
         loop {
-            match self.pump_app_events(None, app) {
+            match self.pump_app_events(None, &mut app) {
                 PumpStatus::Exit(0) => {
                     break Ok(());
                 },
@@ -443,7 +443,7 @@ impl EventLoop {
     pub fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        mut app: A,
     ) -> PumpStatus {
         if !self.loop_running {
             self.loop_running = true;
@@ -455,13 +455,13 @@ impl EventLoop {
             self.cause = StartCause::Init;
 
             // run the initial loop iteration
-            self.single_iteration(None, app);
+            self.single_iteration(None, &mut app);
         }
 
         // Consider the possibility that the `StartCause::Init` iteration could
         // request to Exit
         if !self.exiting() {
-            self.poll_events_with_timeout(timeout, app);
+            self.poll_events_with_timeout(timeout, &mut app);
         }
         if self.exiting() {
             self.loop_running = false;

src/platform_impl/apple/appkit/event_loop.rs

@@ -243,7 +243,7 @@ impl EventLoop {
         &self.window_target
     }
 
-    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: A) -> Result<(), EventLoopError> {
         self.run_app_on_demand(app)
     }
 
@@ -253,9 +253,9 @@ impl EventLoop {
     // redundant wake ups.
     pub fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
-        app: &mut A,
+        mut app: A,
     ) -> Result<(), EventLoopError> {
-        self.delegate.set_event_handler(app, || {
+        self.delegate.set_event_handler(&mut app, || {
             autoreleasepool(|_| {
                 // clear / normalize pump_events state
                 self.delegate.set_wait_timeout(None);
@@ -291,9 +291,9 @@ impl EventLoop {
     pub fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        mut app: A,
     ) -> PumpStatus {
-        self.delegate.set_event_handler(app, || {
+        self.delegate.set_event_handler(&mut app, || {
             autoreleasepool(|_| {
                 // As a special case, if the application hasn't been launched yet then we at least
                 // run the loop until it has fully launched.

src/platform_impl/apple/uikit/event_loop.rs

@@ -109,10 +109,10 @@ impl OwnedDisplayHandle {
     }
 }
 
-fn map_user_event<A: ApplicationHandler>(
-    app: &mut A,
+fn map_user_event<'a, A: ApplicationHandler + 'a>(
+    mut app: A,
     proxy_wake_up: Arc<AtomicBool>,
-) -> impl FnMut(Event, &RootActiveEventLoop) + '_ {
+) -> impl FnMut(Event, &RootActiveEventLoop) + 'a {
     move |event, window_target| match event {
         Event::NewEvents(cause) => app.new_events(window_target, cause),
         Event::WindowEvent { window_id, event } => {
@@ -168,7 +168,7 @@ impl EventLoop {
         })
     }
 
-    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> ! {
+    pub fn run_app<A: ApplicationHandler>(self, app: A) -> ! {
         let application: Option<Retained<UIApplication>> =
             unsafe { msg_send_id![UIApplication::class(), sharedApplication] };
         assert!(

src/platform_impl/linux/mod.rs

@@ -788,13 +788,13 @@ impl EventLoop {
         }
     }
 
-    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(self, app: A) -> Result<(), EventLoopError> {
         x11_or_wayland!(match self; EventLoop(evlp) => evlp.run_app(app))
     }
 
     pub fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
-        app: &mut A,
+        app: A,
     ) -> Result<(), EventLoopError> {
         x11_or_wayland!(match self; EventLoop(evlp) => evlp.run_app_on_demand(app))
     }
@@ -802,7 +802,7 @@ impl EventLoop {
     pub fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        app: A,
     ) -> PumpStatus {
         x11_or_wayland!(match self; EventLoop(evlp) => evlp.pump_app_events(timeout, app))
     }

src/platform_impl/linux/wayland/event_loop/mod.rs

@@ -160,16 +160,16 @@ impl EventLoop {
         Ok(event_loop)
     }
 
-    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: A) -> Result<(), EventLoopError> {
         self.run_app_on_demand(app)
     }
 
     pub fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
-        app: &mut A,
+        mut app: A,
     ) -> Result<(), EventLoopError> {
         let exit = loop {
-            match self.pump_app_events(None, app) {
+            match self.pump_app_events(None, &mut app) {
                 PumpStatus::Exit(0) => {
                     break Ok(());
                 },
@@ -194,19 +194,19 @@ impl EventLoop {
     pub fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        mut app: A,
     ) -> PumpStatus {
         if !self.loop_running {
             self.loop_running = true;
 
             // Run the initial loop iteration.
-            self.single_iteration(app, StartCause::Init);
+            self.single_iteration(&mut app, StartCause::Init);
         }
 
         // Consider the possibility that the `StartCause::Init` iteration could
         // request to Exit.
         if !self.exiting() {
-            self.poll_events_with_timeout(timeout, app);
+            self.poll_events_with_timeout(timeout, &mut app);
         }
         if let Some(code) = self.exit_code() {
             self.loop_running = false;
@@ -219,7 +219,7 @@ impl EventLoop {
         }
     }
 
-    pub fn poll_events_with_timeout<A: ApplicationHandler>(
+    fn poll_events_with_timeout<A: ApplicationHandler>(
         &mut self,
         mut timeout: Option<Duration>,
         app: &mut A,

src/platform_impl/linux/x11/mod.rs

@@ -367,16 +367,16 @@ impl EventLoop {
         &self.event_processor.target
     }
 
-    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: A) -> Result<(), EventLoopError> {
         self.run_app_on_demand(app)
     }
 
     pub fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
-        app: &mut A,
+        mut app: A,
     ) -> Result<(), EventLoopError> {
         let exit = loop {
-            match self.pump_app_events(None, app) {
+            match self.pump_app_events(None, &mut app) {
                 PumpStatus::Exit(0) => {
                     break Ok(());
                 },
@@ -404,19 +404,19 @@ impl EventLoop {
     pub fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        mut app: A,
     ) -> PumpStatus {
         if !self.loop_running {
             self.loop_running = true;
 
             // run the initial loop iteration
-            self.single_iteration(app, StartCause::Init);
+            self.single_iteration(&mut app, StartCause::Init);
         }
 
         // Consider the possibility that the `StartCause::Init` iteration could
         // request to Exit.
         if !self.exiting() {
-            self.poll_events_with_timeout(timeout, app);
+            self.poll_events_with_timeout(timeout, &mut app);
         }
         if let Some(code) = self.exit_code() {
             self.loop_running = false;
@@ -435,7 +435,7 @@ impl EventLoop {
             || self.redraw_receiver.has_incoming()
     }
 
-    pub fn poll_events_with_timeout<A: ApplicationHandler>(
+    fn poll_events_with_timeout<A: ApplicationHandler>(
         &mut self,
         mut timeout: Option<Duration>,
         app: &mut A,

src/platform_impl/orbital/event_loop.rs

@@ -500,7 +500,7 @@ impl EventLoop {
         }
     }
 
-    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(mut self, mut app: A) -> Result<(), EventLoopError> {
         let mut start_cause = StartCause::Init;
         loop {
             app.new_events(&self.window_target, start_cause);
@@ -567,7 +567,7 @@ impl EventLoop {
                         orbital_event.to_option(),
                         event_state,
                         &self.window_target,
-                        app,
+                        &mut app,
                     );
                 }
 

src/platform_impl/web/event_loop/mod.rs

@@ -28,11 +28,12 @@ impl EventLoop {
         Ok(EventLoop { elw })
     }
 
-    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> ! {
+    pub fn run_app<A: ApplicationHandler>(self, mut app: A) -> ! {
         let target = RootActiveEventLoop { p: self.elw.p.clone(), _marker: PhantomData };
 
         // SAFETY: Don't use `move` to make sure we leak the `event_handler` and `target`.
-        let handler: Box<dyn FnMut(Event)> = Box::new(|event| handle_event(app, &target, event));
+        let handler: Box<dyn FnMut(Event)> =
+            Box::new(|event| handle_event(&mut app, &target, event));
 
         // SAFETY: The `transmute` is necessary because `run()` requires `'static`. This is safe
         // because this function will never return and all resources not cleaned up by the point we

src/platform_impl/windows/event_loop.rs

@@ -187,13 +187,13 @@ impl EventLoop {
         &self.window_target
     }
 
-    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: A) -> Result<(), EventLoopError> {
         self.run_app_on_demand(app)
     }
 
     pub fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
-        app: &mut A,
+        mut app: A,
     ) -> Result<(), EventLoopError> {
         {
             let runner = &self.window_target.p.runner_shared;
@@ -254,7 +254,7 @@ impl EventLoop {
     pub fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
-        app: &mut A,
+        mut app: A,
     ) -> PumpStatus {
         {
             let runner = &self.window_target.p.runner_shared;