C#绘制椭圆的方法

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 Form4 : Form  {    public Form4()    {      InitializeComponent();    }    bool drawElipse = false;    private void button1_Click(object sender, EventArgs e)    {      this.drawElipse = !this.drawElipse;      using (Graphics g = this.CreateGraphics())      {        if (this.drawElipse)        {          g.FillEllipse(Brushes.DarkBlue, this.ClientRectangle);        }        else        {          g.FillEllipse(SystemBrushes.Control, this.ClientRectangle);        }      }    }    private void Form4_Load(object sender, EventArgs e)    {    }  }}