# Disabling Low level keys in VB



## _mAkA_ (May 23, 2005)

*_mAkA_ stating thanks to khattam brings this new tutorail for disabling low level keys like alt+tab,ctrl+esc.The code goes as:*

'In a module
Option Explicit

Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Public Declare Function GetKeyState Lib "user32" (ByVal nVirtKey As Long) As Integer
Public Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal nCode As Long, ByVal wParam As Long, lParam As Any) As Long
Public Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hHook As Long) As Long
Public Const HC_ACTION = 0
Public Const WM_KEYDOWN = &H100
Public Const WM_KEYUP = &H101
Public Const WM_SYSKEYDOWN = &H104
Public Const WM_SYSKEYUP = &H105
Public Const VK_TAB = &H9
Public Const VK_CONTROL = &H11
Public Const VK_ESCAPE = &H1B
Public Const VK_DELETE = &H2E

Public Const WH_KEYBOARD_LL = 13
Public Const LLKHF_ALTDOWN = &H20

Public Type KBDLLHOOKSTRUCT
    vkCode As Long
    scanCode As Long
    flags As Long
    time As Long
    dwExtraInfo As Long
End Type

Dim p As KBDLLHOOKSTRUCT

Public Function LowLevelKeyboardProc(ByVal nCode As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
   Dim fEatKeystroke As Boolean

   If (nCode = HC_ACTION) Then
      If wParam = WM_KEYDOWN Or wParam = WM_SYSKEYDOWN Or wParam = WM_KEYUP Or wParam = WM_SYSKEYUP Then
         CopyMemory p, ByVal lParam, Len(p)
         fEatKeystroke = _
            ((p.vkCode = VK_TAB) And ((p.flags And LLKHF_ALTDOWN) <> 0)) Or _
            ((p.vkCode = VK_ESCAPE) And ((p.flags And LLKHF_ALTDOWN) <> 0)) Or _
            ((p.vkCode = VK_ESCAPE) And ((GetKeyState(VK_CONTROL) And &H8000) <> 0)) Or _
            ((p.vkCode = VK_CONTROL) And ((p.flags And LLKHF_ALTDOWN) And ((p.flags And VK_DELETE) <> 0)))
                    End If
    End If

    If fEatKeystroke Then
        LowLevelKeyboardProc = -1
    Else
        LowLevelKeyboardProc = CallNextHookEx(0, nCode, wParam, ByVal lParam)
    End If
End Function

'In a form
Option Explicit

Dim hhkLowLevelKybd As Long

Private Sub chkDisable_Click()
If chkDisable = vbChecked Then
    hhkLowLevelKybd = SetWindowsHookEx(WH_KEYBOARD_LL, AddressOf LowLevelKeyboardProc, App.hInstance, 0)
Else
    UnhookWindowsHookEx hhkLowLevelKybd
    hhkLowLevelKybd = 0
End If
End Sub

Private Sub Form_Unload(Cancel As Integer)
If hhkLowLevelKybd <> 0 Then UnhookWindowsHookEx hhkLowLevelKybd
End Sub

'Don't forget to put a check box in the form & name it chkDisable

'I hate people commenting that I have stolen the code from someone


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## sms_solver (May 24, 2005)

I'll try your code!!


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## khattam_ (May 24, 2005)

[edited]


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## _mAkA_ (May 24, 2005)

Who the heck says I'm a thief can prove it.


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