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

// 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

}