Csharp/C Sharp/Event/Message

Cast event sender to a control

<source lang="csharp"> using System; using System.Drawing; using System.Windows.Forms;

class InstantiateHelloWorld {

    public static void Main()
    {
         Form form   = new Form();
         form.Text   = "Instantiate " + form.Text;
         form.Paint += new PaintEventHandler(MyPaintHandler);
  
         Application.Run(form);
    }
    static void MyPaintHandler(object objSender, PaintEventArgs pea)
    {
         Form     form = (Form)objSender;
         Graphics graphics = pea.Graphics;
  
         graphics.DrawString("Hello from InstantiateHelloWorld!", 
                         form.Font, Brushes.Black, 0, 100);
    }

}

</source>

Register Form window message filter

<source lang="csharp">

 using System;
 using System.Windows.Forms;
 using Microsoft.Win32;
 public class MyMessageFilter : IMessageFilter 
 {
   public bool PreFilterMessage(ref Message m) 
   {
     // Intercept the left mouse button down message.
     if (m.Msg == 513) 
     {
       Console.WriteLine("WM_LBUTTONDOWN is: " + m.Msg);
       return true;
     }
     return false;
   }
 }
 public class mainForm : System.Windows.Forms.Form
 {
   private MyMessageFilter msgFliter = new MyMessageFilter();
   public mainForm()
   {
     GetStats();
     Application.ApplicationExit += new EventHandler(Form_OnExit);
     Application.AddMessageFilter(msgFliter);    
   }
   [STAThread]
   static void Main() 
   {
     Application.Run(new mainForm());
   }
   private void GetStats()
   {
     Console.WriteLine(Application.rupanyName+ "  Company:");
     Console.WriteLine(Application.ProductName+ " App Name:");
     Console.WriteLine(Application.StartupPath);
   }
   // Event handlers.
   private void Form_OnExit(object sender, EventArgs evArgs) 
   {
     Console.WriteLine("Exit", "This app is dead...");
     Application.RemoveMessageFilter(msgFliter);
   }
 }

      </source>