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

// 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

}