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VB.Net: Reading NumLock status, even if the App doesn't have focus

Posted on 2011-09-26
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Last Modified: 2012-08-14
Hi,
I need to read the NumLock status in VB.net.
After some Googling I found the following Class:
Public Class KeyState

  Declare Function GetKeyboardState Lib "user32" Alias "GetKeyboardState" (ByVal pbKeyState() As Byte) As Long
  Private KeyCode As Integer

  Public Sub New(ByVal keycode As Integer)
    Me.KeyCode = keycode
  End Sub

  Public Function KeyState() As Boolean
    Dim state(256) As Byte
    GetKeyboardState(state)
    Return (iif(state(Me.KeyCode) = 1, True, False))
  End Function

End Class

This works fine if the App has focus, but does not read the key correctly if another App as focus.

Is there a way to do this?

Thanks,

Richard
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Question by:rpm
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2 Comments
 
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Accepted Solution

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nffvrxqgrcfqvvc earned 500 total points
ID: 36598280
You can use GetKeyState http://msdn.microsoft.com/en-us/library/windows/desktop/ms646301(v=VS.85).aspx
Public Class Form1
    
    Private Declare Auto Function GetKeyState Lib "User32.dll" (ByVal nVirtKey As Integer) As Short

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        '   keyBits(0)= ' low-bit
        '   keyBits(1)= ' high-bit
        '   If the low-order bit is 1, the key is toggled. A key, such as the CAPS LOCK key, is toggled if it is turned on. 
        '   The key is off and untoggled if the low-order bit is 0. A toggle key's indicator light (if any) on the keyboard 
        '   will be on when the key is toggled, and off when the key is untoggled.

        Dim keyBits() As Byte = BitConverter.GetBytes(GetKeyState(Keys.NumLock))
        If keyBits(0) = 1 Then
            Debug.Print("Numlock ON")
        End If

    End Sub
End Class

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by:rpm
ID: 36598372
Great, thanks! That does the trick!

Richard
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