Listing monitors with just EventLoop instead of ActiveEventLoop

[bschwind]

This used to be possible quite awhile ago, but

• It was shifted from EventLoop to EventLoopWindowTarget in Move available_monitors and primary_monitor to EventLoopWindowTarget #1616
• In 0.30, EventLoopWindowTarget was renamed to ActiveEventLoop, and the Deref implementation from EventLoop to EventLoopWindowTarget was removed

The end result is that you can no longer list monitors with a plain EventLoop. Not the end of the world, but I happen to have an application which hasn't migrated to ApplicationHandler yet, and wants to query monitors before constructing a Window.

Is it still something that could be added back to EventLoop, or does it have soundness issues on some platforms and that's why it was removed?

[kchibisov]

You still can list monitors before creating window if you create window inside the event loop as suggested(you don't need to switch to the trait for that), you don't need application handler for that as well.

Listing monitors generally involves communication an sync thus it should have the loop running, this might not be the case on some platforms, but for cross platform API it was a bit unreliable.

[bschwind]

So my application also has its own loop and uses the pump_events function. I suppose I would still just listen for a StartCause::Init or resumed event in the closure, list the monitors there, then construct a window and store it on an Optional field?

Listing monitors generally involves communication an sync thus it should have the loop running, this might not be the case on some platforms, but for cross platform API it was a bit unreliable.

Thanks for the explanation, that makes a lot of sense to move it to ActiveEventLoop if it can cause problems on some platforms.

[kchibisov]

yeah, you can use pump_events to poll the monitors and collect to e.g. Vector during NewEvents, and then do whatever you want.

[bschwind]

Makes sense, thanks for your help!