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|
//! Listen to runtime events.
use crate::core::event::{self, Event};
use crate::core::window;
use crate::subscription::{self, Subscription};
use crate::MaybeSend;
/// Returns a [`Subscription`] to all the ignored runtime events.
///
/// This subscription will notify your application of any [`Event`] that was
/// not captured by any widget.
pub fn listen() -> Subscription<Event> {
listen_with(|event, status| match status {
event::Status::Ignored => Some(event),
event::Status::Captured => None,
})
}
/// Creates a [`Subscription`] that listens and filters all the runtime events
/// with the provided function, producing messages accordingly.
///
/// This subscription will call the provided function for every [`Event`]
/// handled by the runtime. If the function:
///
/// - Returns `None`, the [`Event`] will be discarded.
/// - Returns `Some` message, the `Message` will be produced.
pub fn listen_with<Message>(
f: fn(Event, event::Status) -> Option<Message>,
) -> Subscription<Message>
where
Message: 'static + MaybeSend,
{
#[derive(Hash)]
struct EventsWith;
subscription::filter_map(
(EventsWith, f),
move |event, status| match event {
Event::Window(window::Event::RedrawRequested(_)) => None,
_ => f(event, status),
},
)
}
/// Creates a [`Subscription`] that produces a message for every runtime event,
/// including the redraw request events.
///
/// **Warning:** This [`Subscription`], if unfiltered, may produce messages in
/// an infinite loop.
pub fn listen_raw<Message>(
f: fn(Event, event::Status) -> Option<Message>,
) -> Subscription<Message>
where
Message: 'static + MaybeSend,
{
#[derive(Hash)]
struct RawEvents;
subscription::filter_map((RawEvents, f), f)
}
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