[RESOLVED] Keyboard Hook

[the182guy]

I'm trying to set a hook so that I can respond to a key combo such as Ctrl+O, without having the app in focus.

I've tried the registerhook method but it's not comlpetely global, say if I have a game running the event is not fired when the combo is pressed.

I've looked at DirectInput which worked in VB6 but haven't found a good .net sample.

BTW it's VB2005

Cheers

[Merrion]

For a single key combination a system wide hotkey (as per this component) is probably your best bet.

Under the hood it uses the API call RegisterHotkey...

[the182guy]

Yeah I've tried it mate, it's not truely system wide as it doesn't function when running a game.

[Merrion]

If a game is written using DirectInput (as most are) then nothing will hook it...sorry to be the bringer of bad news.

[bmahler]

You can actually use a low level keyboard hook to get underneath di. This is a class that i use for the purpose of hooking keys for games that I play. And yes, they all use DI. My IsHooked function has some stuff very specific to my uses, so you will have to change it for your needs, but I think this will work for you.

Imports System.Runtime.InteropServices
Imports System.Reflection
Module keyHook

    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

    ' Low-Level Keyboard Constants
    Private Const HC_ACTION As Integer = 0
    Private Const LLKHF_EXTENDED As Integer = &H1
    Private Const MOD_CONTROL As Long = &H2
    Private Const LLKHF_INJECTED As Integer = &H10
    Private Const LLKHF_ALTDOWN As Integer = &H20
    Private Const LLKHF_UP As Integer = &H80
    Private Const LLKHF_DOWN As Integer = &H81


    Public Const VK_CONTROL = &H11  'Control
    Public Const VK_PRIOR = &H21    'PAGE UP key
    Public Const VK_NEXT = &H22     'Page DOWN key

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


    Public Function IsHooked(ByRef Hookstruct As KBDLLHOOKSTRUCT) As Boolean

        Dim keyA, KeyC, KeyQ As Integer
        Dim ini As New IniFile(Application.StartupPath & "\Settings.ini")
        keyA = ini.GetString("KEYS", "Main", 65)
        KeyC = ini.GetString("KEYS", "Comment", 67)
        KeyQ = ini.GetString("KEYS", "Quest", 81)
        frmMain.MinimizeToTrayToolStripMenuItem.Text = "Minimize to Tray (ALT + " & CType(keyA, Keys).ToString
        frmMain.cWind.Text = "Toggle Comments Window (ALT + " & CType(KeyC, Keys).ToString
        frmMain.qWind.Text = "Toggle Quests Window (ALT + " & CType(KeyQ, Keys).ToString

        'Toggle the Main Window
        If (Hookstruct.vkCode = keyA) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) _
            And CBool(Hookstruct.flags And LLKHF_UP) Then
            If Not frmMain.Visible Then
                frmMain.Show()
                frmMain.BringToFront()
            Else
                frmMain.Hide()
            End If
            Return True
        ElseIf (Hookstruct.vkCode = keyA) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) Then
            Return True
        End If

        'Toggle the Comments Window
        If (Hookstruct.vkCode = KeyC) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) _
            And CBool(Hookstruct.flags And LLKHF_UP) Then
            If Not frmComments.Visible Then
                frmComments.Width = cWidth
                frmComments.Height = cHeight
                frmComments.Left = cWindowX
                frmComments.Top = cWindowY
                If cGlass Then
                    frmComments.TransparencyKey = Color.Black
                Else
                    frmComments.Opacity = cTrans / 100
                End If
                frmComments.Show()
            Else
                frmComments.Dispose()
            End If
            Return True
        ElseIf (Hookstruct.vkCode = KeyC) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) Then
            Return True
        End If

        'Toggle the Quests Window
        If (Hookstruct.vkCode = KeyQ) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) _
        And CBool(Hookstruct.flags And LLKHF_UP) Then
            If Not frmQuestInfo.Visible Then
                frmQuestInfo.Width = qWidth
                frmQuestInfo.Height = qHeight
                frmQuestInfo.Left = qWindowX
                frmQuestInfo.Top = qWindowY
                If cGlass Then
                    frmQuestInfo.TransparencyKey = Color.Black
                Else
                    frmQuestInfo.Opacity = qTrans / 100
                End If
                frmQuestInfo.Show()
            Else
                frmQuestInfo.Dispose()
            End If
            Return True
        ElseIf (Hookstruct.vkCode = KeyQ) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) Then
            Return True
        End If
            Return False
    End Function

    Private Sub HookedState(ByVal Text As String)

    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 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()
        callback = New KeyboardHookDelegate(AddressOf KeyboardCallback)

        KeyboardHandle = SetWindowsHookEx( _
          WH_KEYBOARD_LL, callback, _
          Marshal.GetHINSTANCE( _
          [Assembly].GetExecutingAssembly.GetModules()(0)).ToInt32, 0)

        Call CheckHooked()
    End Sub

    Public Sub CheckHooked()
        If Not (Hooked()) Then
            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

End Module

Just a side note, this does not work in the ide, you must compile your project and run it for the hook to properly work. Not really sure why this happens, but it does.

[kleinma]

yeah there is always SOME underlying method to be global.. otherwise those game comm apps like teamspeak and vent wouldn't work when you were playing Dx games...

[the182guy]

Cheers lads I'll give that class a try. Yeah like I said before, I've had it working with DI through VB6 but haven't come across a decent .net sample till now.

[the182guy]

The code is giving me the "hook failed" error when I call HookKeyboard(). I commented your stuff out, and just inserted a msgbox to test it.

Also... how do I hook key A from example, as when you get the keycode your getting it from your ini file, is it ASCII codes?

[bmahler]

The code is giving me the "hook failed" error when I call HookKeyboard(). I commented your stuff out, and just inserted a msgbox to test it.

Also... how do I hook key A from example, as when you get the keycode your getting it from your ini file, is it ASCII codes?

It is Virtual Keys, just use the Keys enum. like so

If (Hookstruct.vkCode = Keys.A) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) _
    And CBool(Hookstruct.flags And LLKHF_UP) Then
    'Do something
    Return True
ElseIf (Hookstruct.vkCode = Keys.A) And CBool(Hookstruct.flags And LLKHF_ALTDOWN) Then
    Return True
End If

Also about it saying the hook failed, did you read the part in my post that said this does not work when run from the ide. You need ot compile the project and run the executable to test it. When run from the IDE you will always get a hook failed error.

[the182guy]

Works 100%. Cheers mate, exactly what I needed.

Edit: I can't rate you again yet, I will when I can mate.