C#处理Paint事件的方法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsApplication2
{
  public partial class Form5 : Form
  {
    bool drawElipse = false;
    public Form5()
    {
      InitializeComponent();
      this.SetStyle(ControlStyles.ResizeRedraw, true);
    }
    private void Form5_Load(object sender, EventArgs e)
    {
    }
    private void button1_Click(object sender, EventArgs e)
    {
      this.drawElipse = !this.drawElipse;
      this.Invalidate(true);
    }
    private void Form5_Paint(object sender, PaintEventArgs e)
    {
      if (!this.drawElipse) return;
      Graphics g = e.Graphics;
      g.FillEllipse(Brushes.DarkBlue, this.ClientRectangle);
    }
  }
}