Callback errors

[Xa0z]

Callbacks seem to be a really big problem to me. A couple of years ago everything went fine when I subclassed a control or something. But now I try to Debug my own thread and again my VB quits without errormessage:

MODULE

Public Const WH_DEBUG = 9
 
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 UnhookWindowsHookEx Lib "user32" (ByVal hHook 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 GetCurrentThreadId Lib "kernel32" () As Long
 
Public hHook As Long
 
Public Function DebugProc(ncode As Integer, wParam As Long, lParam As Long) As Long
CallNextHookEx hHook, ncode, wParam, lParam
End Function

FORM

Private Sub Form_Load()
hHook = SetWindowsHookEx(WH_DEBUG, AddressOf DebugProc, 0&, GetCurrentThreadId())
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
hHook = UnhookWindowsHookEx(hHook)
End Sub

I hate it when it does quitting without errormessage. I think my code above is right but maybe one of you might see some errors

[Xa0z]

I have simplified this code so it's really short. I hope everyone understands it, otherwise, just ask and I'll explain

[Xa0z]

Nobody able to help? it's just a SetWindowsHookEx function call. Somebody should be familiar with this API

[MerrionComputin]

Somebody is.

The debugproc definition you have is wrong. It should be thus:-

Public Function DebugProc(ByVal ncode As Integer,ByVal wParam As Long,ByVal  lParam As Long) As Long
 
DebugProc = CallNextHookEx(hHook, ncode, wParam, lParam)
 
End Function

Because otherwise you are getting the address of nCode, wparam and lParam and passing that out as the value to CallNextHookEx.

Hope this helps,
Duncan

[Xa0z]

Well, I changed it, to what you were saying but it still crashes unfortunatly . But it was an error, tnx 4 noticing it

[MerrionComputin]

Also, don't use "As Any"...

Public Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long,ByVal lParam As Long) As Long

HTH,
Duncan

[Xa0z]

It was in the API viewer defined like that :P

And it still crashes , am i doomed to fail in using callbacks or something