delegate IntPtr HookProc(int code, IntPtr wParam, IntPtr lParam);

Private Delegate Function HookProc(ByVal code As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer

Identical to HookProc

///     C++ ( lpfn [in]. Type: HOOKPROC )<br />A pointer to the hook procedure. If the dwThreadId parameter

static extern IntPtr SetWindowsHookEx(HookType hookType, HookProc lpfn, IntPtr hMod, uint dwThreadId);

Private Shared Function SetWindowsHookEx(ByVal hookType As HookType, ByVal lpfn As HookProc, ByVal hMod As IntPtr, ByVal dwThreadId As UInteger) As IntPtr

A HookProc delegate representing the hook procedure method. Used as the value passed into lpfn (long pointer to function).

Remember to keep the HookProc delegate alive manually, such as using a class member as shown in the example below, otherwise the garbage collector will clean up your hook delegate eventually, resulting in your code throwing a System.NullReferenceException.

     private HookProc myCallbackDelegate = null;

     this.myCallbackDelegate = new HookProc(this.MyCallbackFunction);

     protected static extern IntPtr SetWindowsHookEx(HookType code, HookProc func, IntPtr hInstance, int threadID);

    Delegate Function HookProc(ByVal code As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As Integer

    Private myCallbackDelegate As HookProc = Nothing

    Me.myCallbackDelegate = New HookProc(AddressOf Me.MyCallbackFunction)

    Friend Shared Function SetWindowsHookEx(ByVal idHook As Integer, ByVal lpfn As HookProc, ByVal hInstance As IntPtr, ByVal threadId As Integer) As Integer

    '  LPOFNHOOKPROC lpfnHook;

typedef UINT_PTR (CALLBACK *LPOFNHOOKPROC) (HWND,UINT,WPARAM,LPARAM);

     LPOFNHOOKPROC lpfnHook;

    '  LPOFNHOOKPROC lpfnHook;