Question

I am wondering if it is possible to make and Raise an event from a class, to a form? I have a class that just loops through itself continually, but when a condition is met I want a button to become visible on a form. I am looking into different ways of accomplishing this. It is probably worth mentioning that I am multithreading and this loop is being run in a different thread than the UI is at. Which is why I am hoping it is possible to raise an event and that will jump over to the UI thread and make the button visible then come back to where it was in the loop.

Any suggestions or direction is appreciated.

Answer 1

Something like this would work,

Public Class MyClass

   Public Event MyEvent()

   Sub DoStuff()
       RaiseEvent MyEvent
   End Sub
Public Class

Public Class MyForm 

    Public Sub HandleEvent()
         'can be called from another thread, so use invoke
         Me.Invoke(Sub() MyButton.Visible = true )
    End Sub

End Class

Dim mMyClass = New MyClass
Dim mMyForm = New MyForm 

AddHandler mMyClass.MyEvent, AddressOf mMyForm.HandleEvent()

As long as you remember to use .Invoke when updating the UI if your event is coming from another thread, there is no issue with having a form handle events from any source.