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

 // COPYRIGHT: Prosoft-Lanz

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

 //

 // $Workfile: WndProcRetHook.cs $

 //

 // PROJECT : CodeProject Components

 // VERSION : 1.00

 // CREATION : 19.02.2003

 // AUTHOR : JCL

 //

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

 //           From MSDN, Dino Esposito.

 //

 //           WindowCreate, WindowDestroye and WindowActivate user events.

 //

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

 using System;

 using System.Runtime.InteropServices;

 using System.Diagnostics;

 namespace CodeProject.Win32API.Hook

 {

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

 	#region Enum WndMessage

 	/// <summary>

 	/// windows message.

 	/// </summary>

 	public enum WndMessage : int

 	{

 		/// Sent to the dialog procedure immediately before the dialog is displayed.

 		WM_INITDIALOG = 0x0110,

 		/// Sent to the dialog procedure immediately before the dialog is displayed.

 		WM_UNKNOWINIT = 0x0127

 	}

 	#endregion

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

 	#region Class WndProcRetEventArgs

 	/// Class used for WH_CALLWNDPROCRET hook event arguments.

 	public class WndProcRetEventArgs : EventArgs

 	{

 		/// wParam parameter.

 		public IntPtr wParam;

 		/// lParam parameter.

 		public IntPtr lParam;

 		/// CWPRETSTRUCT structure.

 		public CwPRetStruct cw;

 		internal WndProcRetEventArgs(IntPtr wParam, IntPtr lParam)

 		{

 			this.wParam = wParam;

 			this.lParam = lParam;

 			cw = new CwPRetStruct();

 			Marshal.PtrToStructure(lParam, cw);

 		}

 	}

 	/// <summary>

 	/// CWPRETSTRUCT structure.

 	/// </summary>

 	[StructLayout(LayoutKind.Sequential)]

 	public class CwPRetStruct

 	{

 		/// Return value.

 		public int lResult;

 		/// lParam parameter.

 		public int lParam;

 		/// wParam parameter.

 		public int wParam;

 		/// Specifies the message.

 		public WndMessage message;

 		/// Handle to the window that processed the message.

 		public IntPtr hwnd;

 	}

 	#endregion

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

 	#region Class WndProcRetHook

 	/// <summary>

 	/// Class to expose the windows WH_CALLWNDPROCRET hook mechanism.

 	/// </summary>

 	public class WndProcRetHook : WindowsHook

 	{

 		/// <summary>

 		/// WH_CALLWNDPROCRET hook delegate method.

 		/// </summary>

 		public delegate void WndProcEventHandler(object sender, WndProcRetEventArgs e);

 		private IntPtr hWndHooked;

 		/// <summary>

 		/// Window procedure event.

 		/// </summary>

 		public event WndProcEventHandler WndProcRet;

 		/// <summary>

 		/// Construct a WH_CALLWNDPROCRET hook.

 		/// </summary>

 		/// <param name="hWndHooked">

 		/// Handle of the window to be hooked. IntPtr.Zero to hook all window.

 		/// </param>

 		public WndProcRetHook(IntPtr hWndHooked) : base(HookType.WH_CALLWNDPROCRET)

 		{

 			this.hWndHooked = hWndHooked;

 			this.HookInvoke += new HookEventHandler(WndProcRetHookInvoked);

 		}

 		/// <summary>

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

 		/// </summary>

 		/// <param name="hWndHooked">

 		/// Handle of the window to be hooked. IntPtr.Zero to hook all window.

 		/// </param>

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

 		public WndProcRetHook(IntPtr hWndHooked, HookProc func) : base(HookType.WH_CALLWNDPROCRET, func)

 		{

 			this.hWndHooked = hWndHooked;

 			this.HookInvoke += new HookEventHandler(WndProcRetHookInvoked);

 		}

 		// handles the hook event

 		private void WndProcRetHookInvoked(object sender, HookEventArgs e)

 		{

 			WndProcRetEventArgs wpe = new WndProcRetEventArgs(e.wParam, e.lParam);

 			if ((hWndHooked == IntPtr.Zero || wpe.cw.hwnd == hWndHooked) && WndProcRet != null)

 				WndProcRet(this, wpe);

 			return;

 		}

 	}

 	#endregion

 }