How do I build a new window inside run_forever or poll_events?

[wez]

I'd like to be able to spawn a new window in response to user input.

Since the event loop is borrowed mutably by run_forever and poll_events, there doesn't appear to be a way to spawn new windows in response to input events.

This may be another facet of #231

[jwilm]

One option is to simply break out of the event loop in that case:

loop {
    let mut flag = false;
    events.run_forever(|event| {
        match event {
            // Event you care about
            flag = true;
            return ControlFlow::Break;
        }
    });
    if flag {
        windows.push(Window::new(&events));
    }
}

[wez]

Sure, but that's not inside the callback :-p
I'm using run_forever for maximum idle reasons, so if I have to break out of the loop its now on me to find a way to efficiently sleep without lagging on processing events per all of the discussion in #231.

[wez]

oh, I misread your comment; I didn't really notice that you could call run forever again

[marek-g]

I've encountered the same problem.

I think what could be easily done to solve the problem is to add &mut EventsLoop parameter to the callback:

events.run_forever_mut(|event, events| { .... /* you can now use "events" to create new window here */ }

I hope rust allows it :)

To have backward compatible API it could be a new method like run_forever_mut.

--

Or.. other idea.. is to use interior mutability for EventsLoop. In that case it would be easy to pass the reference to EventLoop anywhere.

[Osspial]

This should be fixed by the EventLoop 2.0 API rework, when that gets merged.

[MendyBerger]

Now you'd use the EventLoopWindowTarget that you get in the run method, right?

[daxpedda]

Yes, new windows are created with Window::new() , which takes a EventLoopWindowTarget.