Shaohen’s C# Windows Form

Mouse Enter

The event MouseEnter will be called when the mouse enteres a control.

MouseLeave

MouseLeave is raised when the mouse leaves the control.

MouseHover

MouseHoever event occurs after the cursor has entered the control (or the client area) and has stopped moving. The MouseHoever event occurs at most only once between MouseEnter and MouseLeave events.

Sample Code

Here’s a code that demonstrates the mentioned events, modified from Petzold’s Programming Windows with C#.

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Diagnostics;

class EnterLeave : Form
 {
 bool bInside = false;
 
 public static void Main()
  {
  Application.Run(new EnterLeave() );
  }
  
 public EnterLeave()
  {
  Text = "Enter / Leave ";
  Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
  }
  
 protected override void OnMouseEnter(EventArgs e)
  {
  bInside = true;
  Invalidate();
  Trace.WriteLine("OnMouseEnter called");
  
  }

 protected override void OnMouseLeave(EventArgs e)
  {
  bInside = false;
  Invalidate();
  Trace.WriteLine("OnMouseLeave called");
  }

 protected override void OnMouseHover(EventArgs e)
  {
  Graphics grfx = CreateGraphics();
  
  grfx.Clear(Color.Red);
  System.Threading.Thread.Sleep(100);
  grfx.Clear(Color.Green);
  grfx.Dispose();
  Trace.WriteLine("OnMouseHover called");
  }

 protected override void OnPaint(PaintEventArgs e)
  {
  Graphics grfx = e.Graphics;
  
  grfx.Clear(bInside ? Color.Green : BackColor);
  }

 
 
 }