Question: WinUI interfering with MIDI APIs

[tristanlabelle]

I am using the midiIn APIs to get a callback when I press notes on my connected (piano) keyboard. This works fine with a console application, but I never get any callbacks in my WinUI application. The midi objects are created in the Application.OnLaunched method, so they should have main thread affinity.

Does WinUI does not run a standard Win32 PeekMessage/DispatchMessage loop on the main thread? Is there a way to make it do so?

It would be possible to create a separate thread for my midi objects and run my own message loop there, but this is a good amount of extra complexity that I would rather avoid, and I'm not sure that would fix the issue.

Thanks for any suggestions

[tristanlabelle]

I added an artificial message loop after my call to midiInStart and I'm still not receiving callbacks. Moreover, with the same message loop in a console app, the message loop is not pumping anything but I'm receiving callbacks. It looks like this doesn't have to do with message pumping. What could be different in a WinUI app to prevent the callbacks? :/

        while (GetMessage(out var msg, default, 0, 0))
        {
            TranslateMessage(in msg);
            DispatchMessage(in msg);
        }

[tristanlabelle]

It appears to be a bug with the .NET debugger. I filed an issue below but I'll leave the WinUI team close this question in case they have insights.

dotnet/runtime#64668

[StephenLPeters]

@MikeHillberg thoughts?

[github-actions]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.