winit-sonoma-fix/examples/handling_close.rs
Robert Bragg 0d366ffbda Re-work event loop run() API so it can return a Result
This re-works the portable `run()` API that consumes the `EventLoop` and
runs the loop on the calling thread until the app exits.

This can be supported across _all_ platforms and compared to the
previous `run() -> !` API is now able to return a `Result` status on all
platforms except iOS and Web. Fixes: #2709

By moving away from `run() -> !` we stop calling `std::process::exit()`
internally as a means to kill the process without returning which means
it's possible to return an exit status and applications can return from
their `main()` function normally.

This also fixes Android support where an Activity runs in a thread but
we can't assume to have full ownership of the process (other services
could be running in separate threads).

Additionally all examples have generally been updated so that `main()`
returns a `Result` from `run()`

Fixes: #2709
2023-07-28 03:04:32 +04:00

92 lines
3.8 KiB
Rust

#![allow(clippy::single_match)]
use simple_logger::SimpleLogger;
use winit::{
event::{ElementState, Event, KeyEvent, WindowEvent},
event_loop::EventLoop,
keyboard::Key,
window::WindowBuilder,
};
#[path = "util/fill.rs"]
mod fill;
fn main() -> Result<(), impl std::error::Error> {
SimpleLogger::new().init().unwrap();
let event_loop = EventLoop::new();
let window = WindowBuilder::new()
.with_title("Your faithful window")
.build(&event_loop)
.unwrap();
let mut close_requested = false;
event_loop.run(move |event, _, control_flow| {
control_flow.set_wait();
match event {
Event::WindowEvent { event, .. } => {
match event {
WindowEvent::CloseRequested => {
// `CloseRequested` is sent when the close button on the window is pressed (or
// through whatever other mechanisms the window manager provides for closing a
// window). If you don't handle this event, the close button won't actually do
// anything.
// A common thing to do here is prompt the user if they have unsaved work.
// Creating a proper dialog box for that is far beyond the scope of this
// example, so here we'll just respond to the Y and N keys.
println!("Are you ready to bid your window farewell? [Y/N]");
close_requested = true;
// In applications where you can safely close the window without further
// action from the user, this is generally where you'd handle cleanup before
// closing the window. How to close the window is detailed in the handler for
// the Y key.
}
WindowEvent::KeyboardInput {
event:
KeyEvent {
logical_key: key,
state: ElementState::Released,
..
},
..
} => {
// WARNING: Consider using `key_without_modifers()` if available on your platform.
// See the `key_binding` example
match key.as_ref() {
Key::Character("y") => {
if close_requested {
// This is where you'll want to do any cleanup you need.
println!("Buh-bye!");
// For a single-window application like this, you'd normally just
// break out of the event loop here. If you wanted to keep running the
// event loop (i.e. if it's a multi-window application), you need to
// drop the window. That closes it, and results in `Destroyed` being
// sent.
control_flow.set_exit();
}
}
Key::Character("n") => {
if close_requested {
println!("Your window will continue to stay by your side.");
close_requested = false;
}
}
_ => (),
}
}
_ => (),
}
}
Event::RedrawRequested(_) => {
fill::fill_window(&window);
}
_ => (),
}
})
}