Imports System.Runtime.InteropServices
Imports System.Reflection
Imports System.Drawing
Imports System.Threading
Module Keyboard
<DllImport("kernel32.dll", CharSet:=CharSet.Auto)> _
Public Function GetModuleHandle(ByVal lpModuleName As String) As IntPtr
End Function
Public Declare Function UnhookWindowsHookEx Lib "user32" _
(ByVal hHook As Integer) As Integer
Public Declare Function SetWindowsHookEx Lib "user32" _
Alias "SetWindowsHookExA" (ByVal idHook As Integer, _
ByVal lpfn As KeyboardHookDelegate, ByVal hmod As IntPtr, _
ByVal dwThreadId As Integer) As Integer
Private Declare Function GetAsyncKeyState Lib "user32" _
(ByVal vKey As Integer) As Integer
Private Declare Function CallNextHookEx Lib "user32" _
(ByVal hHook As Integer, _
ByVal nCode As Integer, _
ByVal wParam As Integer, _
ByVal lParam As KBDLLHOOKSTRUCT) As Integer
Public Structure KBDLLHOOKSTRUCT
Public vkCode As Integer
Public scanCode As Integer
Public flags As Integer
Public time As Integer
Public dwExtraInfo As Integer
End Structure
' Low-Level Keyboard Constants
Private Const HC_ACTION As Integer = 0
Private Const LLKHF_EXTENDED As Integer = &H1
Private Const LLKHF_INJECTED As Integer = &H10
Private Const LLKHF_ALTDOWN As Integer = &H20
Private Const LLKHF_UP As Integer = &H80
' Virtual Keys
Public Const VK_TAB As Integer = &H9
Public Const VK_CONTROL As Integer = &H11
Public Const VK_ESCAPE As Integer = &H1B
Public Const VK_DELETE As Integer = &H2E
Private Const WH_KEYBOARD_LL As Integer = 13
Public KeyboardHandle As Integer
' Implement this function to block as many
' key combinations as you'd like
Public Function IsHooked( _
ByRef Hookstruct As KBDLLHOOKSTRUCT) As Boolean
Debug.WriteLine("Hookstruct.vkCode: " & Hookstruct.vkCode)
Debug.WriteLine(Hookstruct.vkCode = VK_ESCAPE)
Debug.WriteLine(Hookstruct.vkCode = VK_TAB)
'MessageBox.Show(Hookstruct.vkCode.ToString)
If (Hookstruct.vkCode = VK_ESCAPE) And _
CBool(GetAsyncKeyState(VK_CONTROL) _
And &H8000) Then
Call HookedState("Ctrl + Esc blocked")
Return True
End If
If (Hookstruct.vkCode = VK_TAB) And _
CBool(Hookstruct.flags And _
LLKHF_ALTDOWN) Then
Call HookedState("Alt + Tab blockd")
Return True
End If
If (Hookstruct.vkCode = VK_ESCAPE) And _
CBool(Hookstruct.flags And _
LLKHF_ALTDOWN) Then
Call HookedState("Alt + Escape blocked")
Return True
End If
'' disable PrintScreen here
If (Hookstruct.vkCode = 44) Then
Call HookedState("Print blocked")
Return True
End If
Return False
End Function
Private Sub HookedState(ByVal Text As String)
Debug.WriteLine(Text)
End Sub
Public Function KeyboardCallback(ByVal Code As Integer, _
ByVal wParam As Integer, _
ByRef lParam As KBDLLHOOKSTRUCT) As Integer
If (Code = HC_ACTION) Then
Debug.WriteLine("Calling IsHooked")
If (IsHooked(lParam)) Then
Return 1
End If
End If
Return CallNextHookEx(KeyboardHandle, _
Code, wParam, lParam)
End Function
Public Delegate Function KeyboardHookDelegate( _
ByVal Code As Integer, _
ByVal wParam As Integer, ByRef lParam As KBDLLHOOKSTRUCT) _
As Integer
<MarshalAs(UnmanagedType.FunctionPtr)> _
Private callback As KeyboardHookDelegate
Public Sub HookKeyboard(ByRef f As Form)
callback = New KeyboardHookDelegate(AddressOf KeyboardCallback)
KeyboardHandle = SetWindowsHookEx(WH_KEYBOARD_LL, callback, GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName), 0)
'MessageBox.Show(KeyboardHandle.ToString)
Call CheckHooked()
End Sub
Public Sub CheckHooked()
If (Hooked()) Then
Debug.WriteLine("Keyboard hooked")
Else
Debug.WriteLine("Keyboard hook failed: " & Err.LastDllError)
End If
End Sub
Private Function Hooked() As Boolean
Hooked = KeyboardHandle <> 0
End Function
Public Sub UnhookKeyboard()
If (Hooked()) Then
Call UnhookWindowsHookEx(KeyboardHandle)
End If
End Sub
End Module