using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;using System.Drawing.Drawing2D;namespace WindowsApplication2{  public partial class Form11 : Form  {    public Form11()    {      InitializeComponent();    }    private void button1_Click(object sender, EventArgs e)    {      LinearGradientBrush brush = new LinearGradientBrush(this.ClientRectangle, Color.Empty, Color.Empty, 100);      ColorBlend blend = new ColorBlend();      blend.Colors = new Color[] { Color.Red, Color.Green, Color.Blue };      blend.Positions = new float[] { 0, .5f, 1 };      brush.InterpolationColors = blend;      Pen pen5 = new Pen(brush);      Graphics g5 = this.CreateGraphics();      Point[] p = new Point[] { new Point(0, 0), new Point(100, 100), new Point(50, 100), new Point(200, 100) };      g5.DrawEllipse(pen5, 0, 0, 100, 100);    }  }}