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Adrian Hernando Solanas
Asked: 2020-05-20 11:42:04 +0800 CST 2020-05-20 11:42:04 +0800 CST

VB.NET PINVOKE GetKeyState Loop

  • 772

I have some error in the following loop and I don't know what it is since it doesn't return any error, it just hangs..

While GetKeyState(Keys.Insert).ToString <> "-127" Or GetKeyState(Keys.Insert).ToString <> "-128"
    If GetKeyState(Keys.Insert).ToString = "-127" Or GetKeyState(Keys.Insert).ToString = "-128" Then
        PosMouse.Text = "OK"
        Exit Sub
    End If
End While

I have 2 programs: listen.exe and main.exe

Pressing a button in the listen.exe program will trigger the loop, so that when "INSERT" is pressed in the main.exe program, the mouse position will be recorded.

So later I can move the mouse to that position.

I got out of trouble with a timer but I'm curious about the solution...

Greetings and thank you very much!

vb.net

1 Answers

  1. Best Answer

    The problem with that loop is that it might block the ui, so the form's events aren't processed, so the keystroke will never actually be read.

    A very simple solution to check if that is it is to put a Application.DoEvents()inside the loop:

    While GetKeyState(Keys.Insert).ToString <> "-127" Or GetKeyState(Keys.Insert).ToString <> "-128"
    If GetKeyState(Keys.Insert).ToString = "-127" Or GetKeyState(Keys.Insert).ToString = "-128" Then
        PosMouse.Text = "OK"
        Exit Sub
    End If
    Application.DoEvents()
End While

    But the normal thing is that this code is in another thread, using BackGroundWorkerorTask

    • 2