How to suppress events when async?

[wrekklol]

I'm trying to figure out how to suppress events when running the hook async, but with no luck. If it isn't possible, how would I do it without async, but still not have it block my applications main thread?

[TolikPylypchuk]

Hello! Thanks for asking!

In order to have the ability to suppress events you need to use SimpleGlobalHook - TaskPoolGlobalHook doesn't support suppressing events since it runs event handlers on other threads.

It doesn't matter if you use Run or RunAsync to run the global hook - SimpleGlobalHook allows suppressing events either way.

Also, please note that suppressing events works only on Windows and macOS, it doesn't work on Linux.

[TolikPylypchuk]

Unfortunately, no, there is no way to suppress events with TaskPoolGlobalHook as suppression must be done on the same thread on which the event handler itself runs. The event handler inside TaskPoolGlobalHook delegates processing to other threads while the one in SimpleGlobalHook does not.

Maybe, you can push the decision to suppress the event or not as early as possible, suppress it (or not) and then continue processing the event on a different thread? I think it would be fairly easy with SharpHook.Reactive - if you're familiar with Rx.NET.

If you need to handle only keyboard events, you can create a keyboard-only global hook by passing GlobalHookType.Keyboard to the hook's constructor. This way at least the mouse won't lag if processing takes a long time.

Also, bear in mind that Windows can silently disable global hooks which take too long (without notifications of any kind).

Thanks for the kind words about the library, I really appreciate it!

[wrekklol]

I've never used Rx.NET, but I'll give it a go, thanks for your help! :)

[TolikPylypchuk]

Ah, well, if you've never used Rx.NET then such a thing won't really be easy :) There's a lot of stuff to learn and the learning curve is a little steep.

If you want to try anyway then you need to look into schedulers - they can be used to move event processing to other contexts.

[wrekklol]

I just got a thought, I know you cannot make two hooks currently, but what if you could? So you could have one for suppressing on the main thread, and then the one doing the events on another hook which runs on another thread? Sorry if that is a bit confusing.

[TolikPylypchuk]

That sounds a little too convoluted :)

You can always have more than one event handler on a single hook though.