C# Signature:
[DllImport("user32.dll")]
static extern bool GetKeyboardState(byte [] lpKeyState);
VB Signature:
<DllImport("user32.dll")> _
Private Shared Function GetKeyboardState(ByVal keyState As IntPtr) As Boolean
End Function
Notes:
None.
Tips & Tricks:
Please add some!
Sample Code:
Imports System.Runtime.InteropServices
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.Text = "Caps:" & NativeMethods.CapsLockState.ToString
Me.Text &= ", Num: " & NativeMethods.NumLockState.ToString
Me.Text &= ", Scroll: " & NativeMethods.ScrollLockState.ToString
End Sub
End Class
Public Class NativeMethods
Private Shared keyState() As Byte
' If there is a BETTER WAY to marshal this. Please enlighten...
<DllImport("user32.dll")> _
Private Shared Function GetKeyboardState(ByVal keyState As IntPtr) As Boolean
End Function
Private Shared Sub Update()
' Newerize the array...
keyState = New Byte(255) {}
' Allocate a blob of memory to hold the bytes
Dim ptr As IntPtr = Marshal.AllocHGlobal(256)
' Send the pointer to the memory to the function
Dim result As Boolean = GetKeyboardState(ptr)
' If we got a favourable result then copy the bytes to the array
If result = True Then
Marshal.Copy(ptr, keyState, 0, keyState.Length)
End If
' Always free your memory, or else there will be trouble
Marshal.FreeHGlobal(ptr)
' Check for error:
If result = False Then
Debug.WriteLine("GetKeyBoardState error: " & Marshal.GetLastWin32Error)
Throw New Exception("GetKeyBoardState error: " & Marshal.GetLastWin32Error)
End If
End Sub
Public Enum LightState
Off
[On]
End Enum
' Example - the keyboard lights...
Public Shared ReadOnly Property CapsLockState() As LightState
Get
Update()
Dim isOn As Boolean = (keyState(Keys.CapsLock) = 1)
Return IIf(isOn, LightState.On, LightState.Off)
End Get
End Property
Public Shared ReadOnly Property NumLockState() As LightState
Get
Update()
Dim isOn As Boolean = (keyState(Keys.NumLock) = 1)
Return IIf(isOn, LightState.On, LightState.Off)
End Get
End Property
Public Shared ReadOnly Property ScrollLockState() As LightState
Get
Update()
Dim isOn As Boolean = (keyState(Keys.Scroll) = 1)
Return IIf(isOn, LightState.On, LightState.Off)
End Get
End Property
End Class
Alternative Managed API:
Do you know one? Please contribute it!
