C# - GlobalHook Klasse

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows.Forms;


namespace Utilities {
   class globalKeyboardHook {
       #region Constant, Structure and Delegate Definitions
       
       public delegate int keyboardHookProc(int code, int wParam, ref keyboardHookStruct lParam);
       
       public struct keyboardHookStruct {
           public int vkCode;
           public int scanCode;
           public int flags;
           public int time;
           public int dwExtraInfo;
       }
       
       const int WH_KEYBOARD_LL = 13;
       const int WM_KEYDOWN = 0x100;
       const int WM_KEYUP = 0x101;
       const int WM_SYSKEYDOWN = 0x104;
       const int WM_SYSKEYUP = 0x105;
       
       #endregion
       
       
       keyboardHookProc khp;
       
       
       #region Instance Variables
       public List<Keys> HookedKeys = new List<Keys>();
       
       IntPtr hhook = IntPtr.Zero;
       #endregion
       
       #region Events
       
       public event KeyEventHandler KeyDown;
       
       
       public event KeyEventHandler KeyUp;
       
       #endregion
       
       #region Constructors and Destructors
       
       
       
       public globalKeyboardHook() {
           khp = new keyboardHookProc(hookProc);
           hook();
       }
       
       
       ~globalKeyboardHook() {
           unhook();
       }
       #endregion
       
       #region Public Methods
       
       public void hook() {
           IntPtr hInstance = LoadLibrary("User32");
           hhook = SetWindowsHookEx(WH_KEYBOARD_LL, khp, hInstance, 0);
       }
       
       public void unhook() {
           UnhookWindowsHookEx(hhook);
       }
       
       
       
       public int hookProc(int code, int wParam, ref keyboardHookStruct lParam) {
           if (code >= 0) {
               Keys key = (Keys)lParam.vkCode;
               if (HookedKeys.Contains(key)) {
                   KeyEventArgs kea = new KeyEventArgs(key);
                   if ((wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN) && (KeyDown != null)) {
                       KeyDown(this, kea) ;
                   } else if ((wParam == WM_KEYUP || wParam == WM_SYSKEYUP) && (KeyUp != null)) {
                       KeyUp(this, kea);
                   }
                   if (kea.Handled)
                       return 1;
               }
           }
           return CallNextHookEx(hhook, code, wParam, ref lParam);
       }
       
       #endregion
       
       #region DLL imports
       
       [DllImport("user32.dll")]
       static extern IntPtr SetWindowsHookEx(int idHook, keyboardHookProc callback, IntPtr hInstance, uint threadId);
       
       
       
       [DllImport("user32.dll")]
       static extern bool UnhookWindowsHookEx(IntPtr hInstance);
       
      
       
       [DllImport("user32.dll")]
       static extern int CallNextHookEx(IntPtr idHook, int nCode, int wParam, ref keyboardHookStruct lParam);
      
       
      
       [DllImport("kernel32.dll")]
       static extern IntPtr LoadLibrary(string lpFileName);
       
       #endregion
   }
}