[Vb.net] Keyboard Hook?

ppl2pass · 2010-07-11T18:04:23.000Z

How can i use the keyboard hook by nextgen1 to see if a button is pressed? If F2 is pressed 'Activate Code End If

Nextgen's keyboard never worked for me. Here's my modification of the hook:

First create a module. Add the following namespace:

Code:

Imports System.Runtime.InteropServices

Then add the following declarations:

Code:

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 Integer, _
      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

    Private Declare Function GetModuleHandleA _
    Lib "kernel32.dll" (ByVal fakezero As IntPtr) _
    As IntPtr
    ' 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 = &H9
    Public Const VK_CONTROL = &H11
    Public Const VK_ESCAPE = &H1B
    Public Const VK_DELETE = &H2E

    Private Const WH_KEYBOARD_LL As Integer = 13&
    Public KeyboardHandle As Integer

Then add these sub procedures:

Code:

 ' Implement this function to block as many
    ' key combinations as you'd like
    Public Function IsHooked( _
      ByRef Hookstruct As KBDLLHOOKSTRUCT) As Boolean
 
        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
        MsgBox("Hookstruct.vkCode: " & Hookstruct.vkCode)
    End Function
    Private Sub HookedState(ByVal Text As String)
        MsgBox(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
            If (IsHooked(lParam)) Then
                Return 1
            End If
        End If
        Return 0

    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()
        callback = New KeyboardHookDelegate(AddressOf KeyboardCallback)

        KeyboardHandle = SetWindowsHookEx( _
WH_KEYBOARD_LL, _
callback, _
GetModuleHandleA(IntPtr.Zero), _
0)
        Call CheckHooked()
    End Sub

    Public Sub CheckHooked()
        If (Hooked()) Then
            MsgBox("Keyboard hooked")
        Else
            MsgBox("Keyboard hook failed: " & Err.LastDllError)
        End If
    End Sub

    Private Function Hooked()
        Hooked = KeyboardHandle <> 0
    End Function

    Public Sub UnhookKeyboard()
        If (Hooked()) Then
            Call UnhookWindowsHookEx(KeyboardHandle)
        End If
    End Sub

Then call the HookKeyboard() method from anywhere you want but remember to unhook before exiting your application.

Code:

Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        HookModule.UnhookKeyboard()
    End Sub

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

The problem with Next's module was that it was throwing null exceptions and results.

Hope this helps !! ^_~

[Vb.net] Keyboard Hook?

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