Merge pull request #804 from hecrj/feature/graceful-exit

Graceful exiting for `Application`

examples/events/src/main.rs

@@ -1,22 +1,30 @@
 use iced::{
-    executor, Align, Application, Checkbox, Clipboard, Column, Command,
-    Container, Element, Length, Settings, Subscription, Text,
+    button, executor, Align, Application, Button, Checkbox, Clipboard, Column,
+    Command, Container, Element, HorizontalAlignment, Length, Settings,
+    Subscription, Text,
 };
+use iced_native::{window, Event};
 
 pub fn main() -> iced::Result {
-    Events::run(Settings::default())
+    Events::run(Settings {
+        exit_on_close_request: false,
+        ..Settings::default()
+    })
 }
 
 #[derive(Debug, Default)]
 struct Events {
     last: Vec<iced_native::Event>,
     enabled: bool,
+    exit: button::State,
+    should_exit: bool,
 }
 
 #[derive(Debug, Clone)]
 enum Message {
     EventOccurred(iced_native::Event),
     Toggled(bool),
+    Exit,
 }
 
 impl Application for Events {
@@ -38,27 +46,35 @@ impl Application for Events {
         _clipboard: &mut Clipboard,
     ) -> Command<Message> {
         match message {
-            Message::EventOccurred(event) => {
+            Message::EventOccurred(event) if self.enabled => {
                 self.last.push(event);
 
                 if self.last.len() > 5 {
                     let _ = self.last.remove(0);
                 }
             }
+            Message::EventOccurred(event) => {
+                if let Event::Window(window::Event::CloseRequested) = event {
+                    self.should_exit = true;
+                }
+            }
             Message::Toggled(enabled) => {
                 self.enabled = enabled;
             }
+            Message::Exit => {
+                self.should_exit = true;
+            }
         };
 
         Command::none()
     }
 
     fn subscription(&self) -> Subscription<Message> {
-        if self.enabled {
-            iced_native::subscription::events().map(Message::EventOccurred)
-        } else {
-            Subscription::none()
-        }
+        iced_native::subscription::events().map(Message::EventOccurred)
+    }
+
+    fn should_exit(&self) -> bool {
+        self.should_exit
     }
 
     fn view(&mut self) -> Element<Message> {
@@ -75,11 +91,22 @@ impl Application for Events {
             Message::Toggled,
         );
 
+        let exit = Button::new(
+            &mut self.exit,
+            Text::new("Exit")
+                .width(Length::Fill)
+                .horizontal_alignment(HorizontalAlignment::Center),
+        )
+        .width(Length::Units(100))
+        .padding(10)
+        .on_press(Message::Exit);
+
         let content = Column::new()
             .align_items(Align::Center)
             .spacing(20)
             .push(events)
-            .push(toggle);
+            .push(toggle)
+            .push(exit);
 
         Container::new(content)
             .width(Length::Fill)

glutin/src/application.rs

@@ -92,10 +92,11 @@ where
         application,
         compositor,
         renderer,
-        context,
         runtime,
         debug,
         receiver,
+        context,
+        settings.exit_on_close_request,
     ));
 
     let mut context = task::Context::from_waker(task::noop_waker_ref());
@@ -139,10 +140,11 @@ async fn run_instance<A, E, C>(
     mut application: A,
     mut compositor: C,
     mut renderer: A::Renderer,
-    context: glutin::ContextWrapper<glutin::PossiblyCurrent, Window>,
     mut runtime: Runtime<E, Proxy<A::Message>, A::Message>,
     mut debug: Debug,
     mut receiver: mpsc::UnboundedReceiver<glutin::event::Event<'_, A::Message>>,
+    context: glutin::ContextWrapper<glutin::PossiblyCurrent, Window>,
+    exit_on_close_request: bool,
 ) where
     A: Application + 'static,
     E: Executor + 'static,
@@ -212,6 +214,8 @@ async fn run_instance<A, E, C>(
                     // Update window
                     state.synchronize(&application, context.window());
 
+                    let should_exit = application.should_exit();
+
                     user_interface =
                         ManuallyDrop::new(application::build_user_interface(
                             &mut application,
@@ -220,6 +224,10 @@ async fn run_instance<A, E, C>(
                             state.logical_size(),
                             &mut debug,
                         ));
+
+                    if should_exit {
+                        break;
+                    }
                 }
 
                 debug.draw_started();
@@ -290,6 +298,7 @@ async fn run_instance<A, E, C>(
                 ..
             } => {
                 if application::requests_exit(&window_event, state.modifiers())
+                    && exit_on_close_request
                 {
                     break;
                 }

native/src/window/event.rs

@@ -12,6 +12,12 @@ pub enum Event {
         height: u32,
     },
 
+    /// The user has requested for the window to close.
+    ///
+    /// Usually, you will want to terminate the execution whenever this event
+    /// occurs.
+    CloseRequested,
+
     /// A window was focused.
     Focused,
 

src/application.rs

@@ -184,6 +184,13 @@ pub trait Application: Sized {
         1.0
     }
 
+    /// Returns whether the [`Application`] should be terminated.
+    ///
+    /// By default, it returns `false`.
+    fn should_exit(&self) -> bool {
+        false
+    }
+
     /// Runs the [`Application`].
     ///
     /// On native platforms, this method will take control of the current thread
@@ -284,6 +291,10 @@ where
     fn scale_factor(&self) -> f64 {
         self.0.scale_factor()
     }
+
+    fn should_exit(&self) -> bool {
+        self.0.should_exit()
+    }
 }
 
 #[cfg(target_arch = "wasm32")]

src/settings.rs

@@ -25,6 +25,10 @@ pub struct Settings<Flags> {
     /// The default value is 20.
     pub default_text_size: u16,
 
+    /// Whether the [`Application`] should exit when the user requests the
+    /// window to close (e.g. the user presses the close button).
+    pub exit_on_close_request: bool,
+
     /// If set to true, the renderer will try to perform antialiasing for some
     /// primitives.
     ///
@@ -46,10 +50,11 @@ impl<Flags> Settings<Flags> {
 
         Self {
             flags,
-            antialiasing: default_settings.antialiasing,
+            window: default_settings.window,
             default_font: default_settings.default_font,
             default_text_size: default_settings.default_text_size,
-            window: default_settings.window,
+            exit_on_close_request: default_settings.exit_on_close_request,
+            antialiasing: default_settings.antialiasing,
         }
     }
 }
@@ -61,10 +66,11 @@ where
     fn default() -> Self {
         Self {
             flags: Default::default(),
-            antialiasing: Default::default(),
+            window: Default::default(),
             default_font: Default::default(),
             default_text_size: 20,
-            window: Default::default(),
+            exit_on_close_request: true,
+            antialiasing: false,
         }
     }
 }
@@ -75,6 +81,7 @@ impl<Flags> From<Settings<Flags>> for iced_winit::Settings<Flags> {
         iced_winit::Settings {
             window: settings.window.into(),
             flags: settings.flags,
+            exit_on_close_request: settings.exit_on_close_request,
         }
     }
 }

winit/src/application.rs

@@ -91,6 +91,13 @@ pub trait Application: Program<Clipboard = Clipboard> {
     fn scale_factor(&self) -> f64 {
         1.0
     }
+
+    /// Returns whether the [`Application`] should be terminated.
+    ///
+    /// By default, it returns `false`.
+    fn should_exit(&self) -> bool {
+        false
+    }
 }
 
 /// Runs an [`Application`] with an executor, compositor, and the provided
@@ -149,10 +156,11 @@ where
         application,
         compositor,
         renderer,
-        window,
         runtime,
         debug,
         receiver,
+        window,
+        settings.exit_on_close_request,
     ));
 
     let mut context = task::Context::from_waker(task::noop_waker_ref());
@@ -196,10 +204,11 @@ async fn run_instance<A, E, C>(
     mut application: A,
     mut compositor: C,
     mut renderer: A::Renderer,
-    window: winit::window::Window,
     mut runtime: Runtime<E, Proxy<A::Message>, A::Message>,
     mut debug: Debug,
     mut receiver: mpsc::UnboundedReceiver<winit::event::Event<'_, A::Message>>,
+    window: winit::window::Window,
+    exit_on_close_request: bool,
 ) where
     A: Application + 'static,
     E: Executor + 'static,
@@ -279,6 +288,8 @@ async fn run_instance<A, E, C>(
                     // Update window
                     state.synchronize(&application, &window);
 
+                    let should_exit = application.should_exit();
+
                     user_interface = ManuallyDrop::new(build_user_interface(
                         &mut application,
                         cache,
@@ -286,6 +297,10 @@ async fn run_instance<A, E, C>(
                         state.logical_size(),
                         &mut debug,
                     ));
+
+                    if should_exit {
+                        break;
+                    }
                 }
 
                 debug.draw_started();
@@ -358,7 +373,9 @@ async fn run_instance<A, E, C>(
                 event: window_event,
                 ..
             } => {
-                if requests_exit(&window_event, state.modifiers()) {
+                if requests_exit(&window_event, state.modifiers())
+                    && exit_on_close_request
+                {
                     break;
                 }
 

winit/src/conversion.rs

@@ -33,6 +33,9 @@ pub fn window_event(
                 height: logical_size.height,
             }))
         }
+        WindowEvent::CloseRequested => {
+            Some(Event::Window(window::Event::CloseRequested))
+        }
         WindowEvent::CursorMoved { position, .. } => {
             let position = position.to_logical::<f64>(scale_factor);
 

winit/src/settings.rs

@@ -23,6 +23,10 @@ pub struct Settings<Flags> {
     ///
     /// [`Application`]: crate::Application
     pub flags: Flags,
+
+    /// Whether the [`Application`] should exit when the user requests the
+    /// window to close (e.g. the user presses the close button).
+    pub exit_on_close_request: bool,
 }
 
 /// The window settings of an application.