A Serious Outlook Style Navigation Pane Control

#region License and Copyright

/*
 
Author:  Jacob Mesu
 
Attribution-Noncommercial-Share Alike 3.0 Unported
You are free:

    * to Share — to copy, distribute and transmit the work
    * to Remix — to adapt the work

Under the following conditions:

    * Attribution — You must attribute the work and give credits to the author or guifreaks.net
    * Noncommercial — You may not use this work for commercial purposes. If you want to adapt
      this work for a commercial purpose, visit guifreaks.net and request the Attribution-Share 
      Alike 3.0 Unported license for free. 

http://creativecommons.org/licenses/by-nc-sa/3.0/

*/
#endregion

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;

namespace Guifreaks.Common
{
   /// <summary>
   /// A Message Loop filter which detect mouse events whilst the popup form is shown
   /// and notifies the owning <see cref="PopupWindowHelper"/> class when a mouse
   /// click outside the popup occurs.
   /// </summary>
   public class PopupWindowHelperMessageFilter : IMessageFilter
   {
      /// <summary>
      /// Raised when the Popup Window is about to be cancelled.  The
      /// <see cref="PopupCancelEventArgs.Cancel"/> property can be
      /// set to <c>true</c> to prevent the form from being cancelled.
      /// </summary>
      public event PopupCancelEventHandler PopupCancel;

      /// <summary>
      /// The popup form
      /// </summary>
      private Form popup = null;
      /// <summary>
      /// The owning <see cref="PopupWindowHelper"/> object.
      /// </summary>
      private PopupWindowHelper owner = null;

      /// <summary>
      /// Constructs a new instance of this class and sets the owning
      /// object.
      /// </summary>
      /// <param name="owner">The <see cref="PopupWindowHelper"/> object
      /// which owns this class.</param>
      public PopupWindowHelperMessageFilter(PopupWindowHelper owner)
      {
         this.owner = owner;
      }

      /// <summary>
      /// Gets/sets the popup form which is being displayed.
      /// </summary>
      public Form Popup
      {
         get
         {
            return this.popup;
         }
         set
         {
            this.popup = value;
         }
      }

      /// <summary>
      /// Checks the message loop for mouse messages whilst the popup
      /// window is displayed.  If one is detected the position is
      /// checked to see if it is outside the form, and the owner
      /// is notified if so.
      /// </summary>
      /// <param name="m">Windows Message about to be processed by the
      /// message loop</param>
      /// <returns><c>true</c> to filter the message, <c>false</c> otherwise.
      /// This implementation always returns <c>false</c>.</returns>
      public bool PreFilterMessage(ref Message m)
      {
         if (this.popup != null)
         {
            switch (m.Msg)
            {
               case NativeMethods.WM_LBUTTONDOWN:
               case NativeMethods.WM_RBUTTONDOWN:
               case NativeMethods.WM_MBUTTONDOWN:
               case NativeMethods.WM_NCLBUTTONDOWN:
               case NativeMethods.WM_NCRBUTTONDOWN:
               case NativeMethods.WM_NCMBUTTONDOWN:
                  OnMouseDown();
                  break;
            }
         }
         return false;
      }

      /// <summary>
      /// Checks the mouse location and calls the OnCancelPopup method
      /// if the mouse is outside the popup form.		
      /// </summary>
      private void OnMouseDown()
      {
         // Get the cursor location
         Point cursorPos = Cursor.Position;
         // Check if it is within the popup form
         if (!popup.Bounds.Contains(cursorPos))
         {
            // If not, then call to see if it should be closed
            OnCancelPopup(new PopupCancelEventArgs(popup, cursorPos));
         }
      }

      /// <summary>
      /// Raises the <see cref="PopupCancel"/> event.
      /// </summary>
      /// <param name="e">The <see cref="PopupCancelEventArgs"/> associated 
      /// with the cancel event.</param>
      protected virtual void OnCancelPopup(PopupCancelEventArgs e)
      {
         if (this.PopupCancel != null)
         {
            this.PopupCancel(this, e);
         }
         if (!e.Cancel)
         {
            owner.ClosePopup();
            // Clear reference for GC
            popup = null;
         }
      }
   }
}