//=============================================================================

 // COPYRIGHT: Prosoft-Lanz

 //=============================================================================

 //

 // $Workfile: WindowsHook.cs $

 //

 // PROJECT : CodeProject Components

 // VERSION : 1.00

 // CREATION : 19.02.2003

 // AUTHOR : JCL

 //

 // DETAILS : This class implement the Windows hook mechanism.

 //           From MSDN, Dino Esposito.

 //

 //-----------------------------------------------------------------------------

 using System;

 using System.Runtime.InteropServices;

 namespace CodeProject.Win32API.Hook

 {

 	///////////////////////////////////////////////////////////////////////

 	#region Class HookEventArgs

 	/// Class used for hook event arguments.

 	public class HookEventArgs : EventArgs

 	{

 		/// Event code parameter.

 		public int code;

 		/// wParam parameter.

 		public IntPtr wParam;

 		/// lParam parameter.

 		public IntPtr lParam;

 		internal HookEventArgs(int code, IntPtr wParam, IntPtr lParam)

 		{

 			this.code = code;

 			this.wParam = wParam;

 			this.lParam = lParam;

 		}

 	}

 	#endregion

 	///////////////////////////////////////////////////////////////////////

 	#region Enum HookType

 	/// Hook Types.

 	public enum HookType : int

 	{

 		/// <value>0</value>

 		WH_JOURNALRECORD = 0,

 		/// <value>1</value>

 		WH_JOURNALPLAYBACK = 1,

 		/// <value>2</value>

 		WH_KEYBOARD = 2,

 		/// <value>3</value>

 		WH_GETMESSAGE = 3,

 		/// <value>4</value>

 		WH_CALLWNDPROC = 4,

 		/// <value>5</value>

 		WH_CBT = 5,

 		/// <value>6</value>

 		WH_SYSMSGFILTER = 6,

 		/// <value>7</value>

 		WH_MOUSE = 7,

 		/// <value>8</value>

 		WH_HARDWARE = 8,

 		/// <value>9</value>

 		WH_DEBUG = 9,

 		/// <value>10</value>

 		WH_SHELL = 10,

 		/// <value>11</value>

 		WH_FOREGROUNDIDLE = 11,

 		/// <value>12</value>

 		WH_CALLWNDPROCRET = 12,		

 		/// <value>13</value>

 		WH_KEYBOARD_LL = 13,

 		/// <value>14</value>

 		WH_MOUSE_LL = 14

 	}

 	#endregion

 	///////////////////////////////////////////////////////////////////////

 	#region Class WindowsHook

 	/// <summary>

 	/// Class to expose the windows hook mechanism.

 	/// </summary>

 	public class WindowsHook

 	{

 		/// <summary>

 		/// Hook delegate method.

 		/// </summary>

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

 		// internal properties

 		internal IntPtr hHook = IntPtr.Zero;

 		internal HookProc filterFunc = null;

 		internal HookType hookType;

 		/// <summary>

 		/// Hook delegate method.

 		/// </summary>

 		public delegate void HookEventHandler(object sender, HookEventArgs e);

 		/// <summary>

 		/// Hook invoke event.

 		/// </summary>

 		public event HookEventHandler HookInvoke;

 		internal void OnHookInvoke(HookEventArgs e)

 		{

 			if (HookInvoke != null)

 				HookInvoke(this, e);

 		}

 		/// <summary>

 		/// Construct a HookType hook.

 		/// </summary>

 		/// <param name="hook">Hook type.</param>

 		public WindowsHook(HookType hook)

 		{

 			hookType = hook;

 			filterFunc = new HookProc(this.CoreHookProc);

 		}

 		/// <summary>

 		/// Construct a HookType hook giving a hook filter delegate method.

 		/// </summary>

 		/// <param name="hook">Hook type</param>

 		/// <param name="func">Hook filter event.</param>

 		public WindowsHook(HookType hook, HookProc func)

 		{

 			hookType = hook;

 			filterFunc = func; 

 		}

 		// default hook filter function

 		internal int CoreHookProc(int code, IntPtr wParam, IntPtr lParam)

 		{

 			if (code < 0)

 				return CallNextHookEx(hHook, code, wParam, lParam);

 			// let clients determine what to do

 			HookEventArgs e = new HookEventArgs(code, wParam, lParam);

 			OnHookInvoke(e);

 			// yield to the next hook in the chain

 			return CallNextHookEx(hHook, code, wParam, lParam);

 		}

 		/// <summary>

 		/// Install the hook. 

 		/// </summary>

 		public void Install()

 		{

 			hHook = SetWindowsHookEx(hookType, filterFunc, IntPtr.Zero, (int)AppDomain.GetCurrentThreadId());

 		}

 		/// <summary>

 		/// Uninstall the hook.

 		/// </summary>

  		public void Uninstall()

 		{

 			if (hHook != IntPtr.Zero)

 			{

 				UnhookWindowsHookEx(hHook);

 				hHook = IntPtr.Zero;

 			}

 		}

 		#region Win32 Imports

 		[DllImport("user32.dll")]

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

 		[DllImport("user32.dll")]

 		internal static extern int UnhookWindowsHookEx(IntPtr hhook); 

 		[DllImport("user32.dll")]

 		internal static extern int CallNextHookEx(IntPtr hhook, int code, IntPtr wParam, IntPtr lParam);

 		#endregion

 	}

 	#endregion

 }