Losing keyboard hook after connection to access

See more:

keyboard

hooking

VB15

I'm having an issue whereby I've setup a keyboard hook in my application that works perfectly from both within my app and when any other app is in the foreground.

I have a need to connect to an external MS Access database, but on doing so I lose the keyboard hook for my main app yet it still works when other apps are in the foreground.

The code for keyboard hook class is :

Imports System.Runtime.InteropServices


Public Class KeyboardHook

    <DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
    Public Overloads Shared Function SetWindowsHookEx(ByVal idHook As Integer, ByVal HookProc As KBDLLHookProc, ByVal hInstance As IntPtr, ByVal wParam As Integer) As Integer
    End Function
    <DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
    Public Overloads Shared Function CallNextHookEx(ByVal idHook As Integer, ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
    End Function
    <DllImport("User32.dll", CharSet:=CharSet.Auto, CallingConvention:=CallingConvention.StdCall)>
    Public Overloads Shared Function UnhookWindowsHookEx(ByVal idHook As Integer) As Boolean
    End Function

    <StructLayout(LayoutKind.Sequential)>
    Private Structure KBDLLHOOKSTRUCT
        Public vkCode As UInt32
        Public scanCode As UInt32
        Public flags As KBDLLHOOKSTRUCTFlags
        Public time As UInt32
        Public dwExtraInfo As UIntPtr
    End Structure

    <Flags()>
    Private Enum KBDLLHOOKSTRUCTFlags As UInt32
        LLKHF_EXTENDED = &H1
        LLKHF_INJECTED = &H10
        LLKHF_ALTDOWN = &H20
        LLKHF_UP = &H80
    End Enum

    Public Shared Event KeyDown(ByVal Key As Keys)
    Public Shared Event KeyUp(ByVal Key As Keys)

    Private Const WH_KEYBOARD_LL As Integer = 13
    Private Const HC_ACTION As Integer = 0
    Private Const WM_KEYDOWN = &H100
    Private Const WM_KEYUP = &H101
    Private Const WM_SYSKEYDOWN = &H104
    Private Const WM_SYSKEYUP = &H105

    Public Delegate Function KBDLLHookProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer

    Public Shared KBDLLHookProcDelegate As KBDLLHookProc = New KBDLLHookProc(AddressOf KeyboardProc)
    Private HHookID As IntPtr = IntPtr.Zero

    Public Shared Function KeyboardProc(ByVal nCode As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer
        If (nCode = HC_ACTION) Then
            Dim struct As KBDLLHOOKSTRUCT
            Select Case wParam
                Case WM_KEYDOWN, WM_SYSKEYDOWN
                    RaiseEvent KeyDown(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
                Case WM_KEYUP, WM_SYSKEYUP
                    RaiseEvent KeyUp(CType(CType(Marshal.PtrToStructure(lParam, struct.GetType()), KBDLLHOOKSTRUCT).vkCode, Keys))
            End Select
        End If
        Return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam)
    End Function

    Public Sub New()
        HHookID = SetWindowsHookEx(WH_KEYBOARD_LL, KBDLLHookProcDelegate, System.Runtime.InteropServices.Marshal.GetHINSTANCE(System.Reflection.Assembly.GetExecutingAssembly.GetModules()(0)).ToInt64, 0)
        If HHookID = IntPtr.Zero Then
            Throw New Exception("Could not set keyboard hook")
        End If
    End Sub

    Protected Overrides Sub Finalize()
        If Not HHookID = IntPtr.Zero Then
            UnhookWindowsHookEx(HHookID)
        End If
        MyBase.Finalize()
    End Sub

End Class

I instantiate the class and use the events with :

Public WithEvents kbHook As New KeyboardHook

   Public Sub kbHook_KeyDown(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyDown
       Select Case Key
           Case Keys.RControlKey
               If lblIndicator.BackColor = Color.Green Then
                   lblIndicator.BackColor = Color.Red
               Else
                   lblIndicator.BackColor = Color.Green
               End If
       End Select
   End Sub

Sample code that I use for connecting to Access :

Dim Conn As ADODB.Connection
       Dim sConnection As String = ""
       Dim C_AccessFileName As String = "C:\Users\LEA132\Documents\Database1.accdb"


       sConnection = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & C_AccessFileName & ";"
       Conn = New ADODB.Connection
       Conn.Open(sConnection)

       Conn.Close()
       Conn = Nothing

As soon as the line

Conn.Open(sConnection)

executes, the keyboard hook will no longer function when my app is in the foreground. It does still work however when another app is in the foreground - it's weird.

I'm at a loss on figuring this one out.

What I have tried:

I have tried lots of different things so far (eg.different methods for access connection), this code comes from a seperate sample project I setup just for trying to solve the problem. It's just a plain single form with a button to trigger the connection to Access and a label that switches it's background colour between red and green on clicking the right control key for the keyboard hook.