winit/platform/
run_return.rs

1use crate::{
2    event::Event,
3    event_loop::{ControlFlow, EventLoop, EventLoopWindowTarget},
4};
5
6/// Additional methods on [`EventLoop`] to return control flow to the caller.
7pub trait EventLoopExtRunReturn {
8    /// A type provided by the user that can be passed through [`Event::UserEvent`].
9    type UserEvent;
10
11    /// Initializes the `winit` event loop.
12    ///
13    /// Unlike [`EventLoop::run`], this function accepts non-`'static` (i.e. non-`move`) closures
14    /// and returns control flow to the caller when `control_flow` is set to [`ControlFlow::Exit`].
15    ///
16    /// # Caveats
17    ///
18    /// Despite its appearance at first glance, this is *not* a perfect replacement for
19    /// `poll_events`. For example, this function will not return on Windows or macOS while a
20    /// window is getting resized, resulting in all application logic outside of the
21    /// `event_handler` closure not running until the resize operation ends. Other OS operations
22    /// may also result in such freezes. This behavior is caused by fundamental limitations in the
23    /// underlying OS APIs, which cannot be hidden by `winit` without severe stability repercussions.
24    ///
25    /// You are strongly encouraged to use `run`, unless the use of this is absolutely necessary.
26    ///
27    /// ## Platform-specific
28    ///
29    /// - **X11 / Wayland:** This function returns `1` upon disconnection from
30    ///   the display server.
31    fn run_return<F>(&mut self, event_handler: F) -> i32
32    where
33        F: FnMut(
34            Event<'_, Self::UserEvent>,
35            &EventLoopWindowTarget<Self::UserEvent>,
36            &mut ControlFlow,
37        );
38}
39
40impl<T> EventLoopExtRunReturn for EventLoop<T> {
41    type UserEvent = T;
42
43    fn run_return<F>(&mut self, event_handler: F) -> i32
44    where
45        F: FnMut(
46            Event<'_, Self::UserEvent>,
47            &EventLoopWindowTarget<Self::UserEvent>,
48            &mut ControlFlow,
49        ),
50    {
51        self.event_loop.run_return(event_handler)
52    }
53}
winit/platform/run_return.rs

winit/platform/
run_return.rs
