Struct EventLoop

pub struct EventLoop<T: 'static> { /* private fields */ }

Provides a way to retrieve events from the system and from the windows that were registered to the events loop.

An EventLoop can be seen more or less as a “context”. Calling EventLoop::new initializes everything that will be required to create windows. For example on Linux creating an event loop opens a connection to the X or Wayland server.

To wake up an EventLoop from a another thread, see the EventLoopProxy docs.

Note that this cannot be shared across threads (due to platform-dependant logic forbidding it), as such it is neither Send nor Sync. If you need cross-thread access, the Window created from this can be sent to an other thread, and the EventLoopProxy allows you to wake up an EventLoop from another thread.

Implementations

impl EventLoop<()>

pub fn new() -> Result<EventLoop<()>, EventLoopError>

Create the event loop.

This is an alias of EventLoop::builder().build().

Examples found in repository

examples/control_flow.rs (line 45)

fn main() -> Result<(), impl std::error::Error> {
    #[cfg(web_platform)]
    console_error_panic_hook::set_once();

    tracing::init();

    info!("Press '1' to switch to Wait mode.");
    info!("Press '2' to switch to WaitUntil mode.");
    info!("Press '3' to switch to Poll mode.");
    info!("Press 'R' to toggle request_redraw() calls.");
    info!("Press 'Esc' to close the window.");

    let event_loop = EventLoop::new().unwrap();

    let mut app = ControlFlowDemo::default();
    event_loop.run_app(&mut app)
}

pub fn builder() -> EventLoopBuilder<()>

Start building a new event loop.

This returns an EventLoopBuilder, to allow configuring the event loop before creation.

To get the actual event loop, call build on that.

impl<T> EventLoop<T>

pub fn with_user_event() -> EventLoopBuilder<T>

Start building a new event loop, with the given type as the user event type.

Examples found in repository

examples/window.rs (line 49)

fn main() -> Result<(), Box<dyn Error>> {
    #[cfg(web_platform)]
    console_error_panic_hook::set_once();

    tracing::init();

    let event_loop = EventLoop::<UserEvent>::with_user_event().build()?;
    let _event_loop_proxy = event_loop.create_proxy();

    // Wire the user event from another thread.
    #[cfg(not(web_platform))]
    std::thread::spawn(move || {
        // Wake up the `event_loop` once every second and dispatch a custom event
        // from a different thread.
        info!("Starting to send user event every second");
        loop {
            let _ = _event_loop_proxy.send_event(UserEvent::WakeUp);
            std::thread::sleep(std::time::Duration::from_secs(1));
        }
    });

    let mut state = Application::new(&event_loop);

    event_loop.run_app(&mut state).map_err(Into::into)
}

pub fn run<F>(self, event_handler: F) -> Result<(), EventLoopError>

where F: FnMut(Event<T>, &ActiveEventLoop),

👎Deprecated: use EventLoop::run_app instead

Available on not (web_platform and target feature exception-handling).

See run_app.

pub fn run_app<A: ApplicationHandler<T>>( self, app: &mut A, ) -> Result<(), EventLoopError>

Available on not (web_platform and target feature exception-handling).

Run the application with the event loop on the calling thread.

See the set_control_flow() docs on how to change the event loop’s behavior.

Platform-specific

• iOS: Will never return to the caller and so values not passed to this function will not be dropped before the process exits.

• Web: Will act as if it never returns to the caller by throwing a Javascript exception (that Rust doesn’t see) that will also mean that the rest of the function is never executed and any values not passed to this function will not be dropped.

  Web applications are recommended to use EventLoopExtWebSys::spawn_app() ¹ instead of run_app() to avoid the need for the Javascript exception trick, and to make it clearer that the event loop runs asynchronously (via the browser’s own, internal, event loop) and doesn’t block the current thread of execution like it does on other platforms.

  This function won’t be available with target_feature = "exception-handling".

---

1. EventLoopExtWebSys::spawn_app() is only available on Web. ↩

Examples found in repository

examples/control_flow.rs (line 48)

fn main() -> Result<(), impl std::error::Error> {
    #[cfg(web_platform)]
    console_error_panic_hook::set_once();

    tracing::init();

    info!("Press '1' to switch to Wait mode.");
    info!("Press '2' to switch to WaitUntil mode.");
    info!("Press '3' to switch to Poll mode.");
    info!("Press 'R' to toggle request_redraw() calls.");
    info!("Press 'Esc' to close the window.");

    let event_loop = EventLoop::new().unwrap();

    let mut app = ControlFlowDemo::default();
    event_loop.run_app(&mut app)
}

examples/window.rs (line 66)

fn main() -> Result<(), Box<dyn Error>> {
    #[cfg(web_platform)]
    console_error_panic_hook::set_once();

    tracing::init();

    let event_loop = EventLoop::<UserEvent>::with_user_event().build()?;
    let _event_loop_proxy = event_loop.create_proxy();

    // Wire the user event from another thread.
    #[cfg(not(web_platform))]
    std::thread::spawn(move || {
        // Wake up the `event_loop` once every second and dispatch a custom event
        // from a different thread.
        info!("Starting to send user event every second");
        loop {
            let _ = _event_loop_proxy.send_event(UserEvent::WakeUp);
            std::thread::sleep(std::time::Duration::from_secs(1));
        }
    });

    let mut state = Application::new(&event_loop);

    event_loop.run_app(&mut state).map_err(Into::into)
}

pub fn create_proxy(&self) -> EventLoopProxy<T>

Creates an EventLoopProxy that can be used to dispatch user events to the main event loop, possibly from another thread.

Examples found in repository

examples/window.rs (line 50)

fn main() -> Result<(), Box<dyn Error>> {
    #[cfg(web_platform)]
    console_error_panic_hook::set_once();

    tracing::init();

    let event_loop = EventLoop::<UserEvent>::with_user_event().build()?;
    let _event_loop_proxy = event_loop.create_proxy();

    // Wire the user event from another thread.
    #[cfg(not(web_platform))]
    std::thread::spawn(move || {
        // Wake up the `event_loop` once every second and dispatch a custom event
        // from a different thread.
        info!("Starting to send user event every second");
        loop {
            let _ = _event_loop_proxy.send_event(UserEvent::WakeUp);
            std::thread::sleep(std::time::Duration::from_secs(1));
        }
    });

    let mut state = Application::new(&event_loop);

    event_loop.run_app(&mut state).map_err(Into::into)
}

pub fn owned_display_handle(&self) -> OwnedDisplayHandle

Gets a persistent reference to the underlying platform display.

See the OwnedDisplayHandle type for more information.

pub fn listen_device_events(&self, allowed: DeviceEvents)

Change if or when DeviceEvents are captured.

See ActiveEventLoop::listen_device_events for details.

pub fn set_control_flow(&self, control_flow: ControlFlow)

Sets the ControlFlow.

pub fn create_window( &self, window_attributes: WindowAttributes, ) -> Result<Window, OsError>

👎Deprecated: use ActiveEventLoop::create_window instead

Create a window.

Creating window without event loop running often leads to improper window creation; use ActiveEventLoop::create_window instead.

pub fn create_custom_cursor( &self, custom_cursor: CustomCursorSource, ) -> CustomCursor

Create custom cursor.

Examples found in repository

examples/window.rs (line 111)

    fn new<T>(event_loop: &EventLoop<T>) -> Self {
        // SAFETY: we drop the context right before the event loop is stopped, thus making it safe.
        #[cfg(not(any(android_platform, ios_platform)))]
        let context = Some(
            Context::new(unsafe {
                std::mem::transmute::<DisplayHandle<'_>, DisplayHandle<'static>>(
                    event_loop.display_handle().unwrap(),
                )
            })
            .unwrap(),
        );

        // You'll have to choose an icon size at your own discretion. On X11, the desired size
        // varies by WM, and on Windows, you still have to account for screen scaling. Here
        // we use 32px, since it seems to work well enough in most cases. Be careful about
        // going too high, or you'll be bitten by the low-quality downscaling built into the
        // WM.
        let icon = load_icon(include_bytes!("data/icon.png"));

        info!("Loading cursor assets");
        let custom_cursors = vec![
            event_loop.create_custom_cursor(decode_cursor(include_bytes!("data/cross.png"))),
            event_loop.create_custom_cursor(decode_cursor(include_bytes!("data/cross2.png"))),
            event_loop.create_custom_cursor(decode_cursor(include_bytes!("data/gradient.png"))),
        ];

        Self {
            #[cfg(not(any(android_platform, ios_platform)))]
            context,
            custom_cursors,
            icon,
            windows: Default::default(),
        }
    }

Trait Implementations

impl<T> Debug for EventLoop<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> EventLoopExtAndroid for EventLoop<T>

Available on android_platform only.

fn android_app(&self) -> &AndroidApp

Get the [AndroidApp] which was used to create this event loop.

impl<T: 'static> EventLoopExtIOS for EventLoop<T>

Available on ios_platform only.

fn idiom(&self) -> Idiom

Returns the Idiom (phone/tablet/tv/etc) for the current device.

impl<T> EventLoopExtPumpEvents for EventLoop<T>

Available on windows_platform or macos_platform or android_platform or x11_platform or wayland_platform only.

type UserEvent = T

A type provided by the user that can be passed through Event::UserEvent.

fn pump_events<F>( &mut self, timeout: Option<Duration>, event_handler: F, ) -> PumpStatus

where F: FnMut(Event<Self::UserEvent>, &ActiveEventLoop),

👎Deprecated: use EventLoopExtPumpEvents::pump_app_events

See pump_app_events.

fn pump_app_events<A: ApplicationHandler<Self::UserEvent>>( &mut self, timeout: Option<Duration>, app: &mut A, ) -> PumpStatus

Pump the EventLoop to check for and dispatch pending events.

impl<T> EventLoopExtRunOnDemand for EventLoop<T>

Available on windows_platform or macos_platform or android_platform or x11_platform or wayland_platform only.

type UserEvent = T

A type provided by the user that can be passed through Event::UserEvent.

fn run_on_demand<F>(&mut self, event_handler: F) -> Result<(), EventLoopError>

where F: FnMut(Event<Self::UserEvent>, &ActiveEventLoop),

👎Deprecated: use EventLoopExtRunOnDemand::run_app_on_demand

See run_app_on_demand.

fn run_app_on_demand<A: ApplicationHandler<Self::UserEvent>>( &mut self, app: &mut A, ) -> Result<(), EventLoopError>

Run the application with the event loop on the calling thread.

impl<T: 'static> EventLoopExtWayland for EventLoop<T>

Available on wayland_platform only.

fn is_wayland(&self) -> bool

True if the EventLoop uses Wayland.

impl<T> EventLoopExtWebSys for EventLoop<T>

Available on web_platform only.

type UserEvent = T

A type provided by the user that can be passed through Event::UserEvent.

fn spawn_app<A: ApplicationHandler<Self::UserEvent> + 'static>(self, app: A)

Initializes the winit event loop.

fn spawn<F>(self, event_handler: F)

where F: 'static + FnMut(Event<Self::UserEvent>, &ActiveEventLoop),

👎Deprecated: use EventLoopExtWebSys::spawn_app

See spawn_app.

fn set_poll_strategy(&self, strategy: PollStrategy)

Sets the strategy for ControlFlow::Poll.

fn poll_strategy(&self) -> PollStrategy

Gets the strategy for ControlFlow::Poll.

fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy)

Sets the strategy for ControlFlow::WaitUntil.

fn wait_until_strategy(&self) -> WaitUntilStrategy

Gets the strategy for ControlFlow::WaitUntil.

impl<T: 'static> EventLoopExtX11 for EventLoop<T>

Available on x11_platform only.

fn is_x11(&self) -> bool

True if the EventLoop uses X11.

impl<T> HasDisplayHandle for EventLoop<T>

Available on crate feature rwh_06 only.

fn display_handle(&self) -> Result<DisplayHandle<'_>, HandleError>

Get a handle to the display controller of the windowing system.

impl<T> HasRawDisplayHandle for EventLoop<T>

Available on crate feature rwh_05 only.

fn raw_display_handle(&self) -> RawDisplayHandle

Returns a rwh_05::RawDisplayHandle for the event loop.