using System; 
 using System.Runtime.InteropServices; 
  
 namespace WeifenLuo.WinFormsUI 
 { 
 	internal class HookEventArgs : EventArgs 
 	{ 
 		public int HookCode;  // Hook code 
 		public IntPtr wParam;   // WPARAM argument 
 		public IntPtr lParam;   // LPARAM argument 
 	} 
  
  
 	// Hook Types   
 	internal enum HookType : int 
 	{ 
 		WH_JOURNALRECORD = 0, 
 		WH_JOURNALPLAYBACK = 1, 
 		WH_KEYBOARD = 2, 
 		WH_GETMESSAGE = 3, 
 		WH_CALLWNDPROC = 4, 
 		WH_CBT = 5, 
 		WH_SYSMSGFILTER = 6, 
 		WH_MOUSE = 7, 
 		WH_HARDWARE = 8, 
 		WH_DEBUG = 9, 
 		WH_SHELL = 10, 
 		WH_FOREGROUNDIDLE = 11, 
 		WH_CALLWNDPROCRET = 12,     
 		WH_KEYBOARD_LL = 13, 
 		WH_MOUSE_LL = 14 
 	} 
  
 	internal class LocalWindowsHook 
 	{ 
 		public delegate int HookProc(int code, IntPtr wParam, IntPtr lParam); 
  
 		[DllImport("user32.dll")] 
 		private static extern IntPtr SetWindowsHookEx(HookType code, HookProc func, IntPtr hInstance, int threadID); 
  
 		[DllImport("user32.dll")] 
 		private static extern int UnhookWindowsHookEx(IntPtr hhook);  
  
 		[DllImport("user32.dll")] 
 		private static extern int CallNextHookEx(IntPtr hhook, int code, IntPtr wParam, IntPtr lParam); 
  
 		// Internal properties 
 		private IntPtr m_hhook = IntPtr.Zero; 
 		private HookProc m_filterFunc = null; 
 		private HookType m_hookType; 
  
 		// Event delegate 
 		public delegate void HookEventHandler(object sender, HookEventArgs e); 
  
 		// Event: HookInvoked  
 		public event HookEventHandler HookInvoked; 
 		protected void OnHookInvoked(HookEventArgs e) 
 		{ 
 			if (HookInvoked != null) 
 				HookInvoked(this, e); 
 		} 
  
 		// Class constructor(s) 
 		public LocalWindowsHook(HookType hook) 
 		{ 
 			m_hookType = hook; 
 			m_filterFunc = new HookProc(this.CoreHookProc); 
 		} 
  
 		public LocalWindowsHook(HookType hook, HookProc func) 
 		{ 
 			m_hookType = hook; 
 			m_filterFunc = func;  
 		}     
  
 		// Default filter function 
 		public int CoreHookProc(int code, IntPtr wParam, IntPtr lParam) 
 		{ 
 			if (code  < 0) 
 				return CallNextHookEx(m_hhook, code, wParam, lParam); 
  
 			// Let clients determine what to do 
 			HookEventArgs e = new HookEventArgs(); 
 			e.HookCode = code; 
 			e.wParam = wParam; 
 			e.lParam = lParam; 
 			OnHookInvoked(e); 
  
 			// Yield to the next hook in the chain 
 			return CallNextHookEx(m_hhook, code, wParam, lParam); 
 		} 
  
 		// Install the hook 
 		public void Install() 
 		{ 
 			int threadId = Kernel32.GetCurrentThreadId(); 
 			m_hhook = SetWindowsHookEx(m_hookType, m_filterFunc, IntPtr.Zero, threadId); 
 		} 
  
 		// Uninstall the hook 
 		public void Uninstall() 
 		{ 
 			UnhookWindowsHookEx(m_hhook);  
 		} 
 	} 
 }