public void FillEllipseWithPathGradient(PaintEventArgs e)
{
    // Create a path that consists of a single ellipse.
    GraphicsPath path = new GraphicsPath();
    path.AddEllipse(0, 0, 140, 70);

    // Use the path to construct a brush.
    PathGradientBrush pthGrBrush = new PathGradientBrush(path);

    // Set the color at the center of the path to blue.
    pthGrBrush.CenterColor = Color.FromArgb(255, 0, 0, 255);

    // Set the color along the entire boundary 
    // of the path to aqua.
    Color[] colors = { Color.FromArgb(255, 0, 255, 255) };
    pthGrBrush.SurroundColors = colors;

    e.Graphics.FillEllipse(pthGrBrush, 0, 0, 140, 70);
}

//引入命名空间
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;

public class Form1 : Form
{

  public Form1() {
        InitializeComponent();
  }
  private void Form1_Paint(object sender, PaintEventArgs e)
  {
      GraphicsPath path = new GraphicsPath();
      int size = 150;
      path.AddEllipse(10, 10, size, size);
      
      PathGradientBrush brush = new PathGradientBrush(path);
      brush.WrapMode = WrapMode.Tile;
      brush.SurroundColors = new Color[] { Color.White };
      brush.CenterColor = Color.Violet;
      e.Graphics.FillRectangle(brush, 10, 10, size, size);
      
      path.Dispose();
      brush.Dispose();
  }

  private void InitializeComponent()
  {
    this.SuspendLayout();
    this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
    this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
    this.ClientSize = new System.Drawing.Size(292, 266);
    this.Name = "Form1";
    this.Text = "Alpha Blending";
    this.Paint += new System.Windows.Forms.PaintEventHandler(this.Form1_Paint);
    this.ResumeLayout(false);

  }


  [STAThread]
  static void Main()
  {
    Application.EnableVisualStyles();
    Application.Run(new Form1());
  }

}

//引入命名空间
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace GradientWrap_c
{
    public class GradientWrap : System.Windows.Forms.Form
    {
        private System.ComponentModel.Container components = null;

        public GradientWrap()
        {
      this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
      this.ClientSize = new System.Drawing.Size(292, 273);
      this.Name = "GradientWrap";
      this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
      this.Text = "GradientWrap";
      this.Load += new System.EventHandler(this.GradientWrap_Load);

        }
        static void Main() 
        {
            Application.Run(new GradientWrap());
        }

    private void GradientWrap_Load(object sender, System.EventArgs e)
    {
    
    }

    protected override void OnPaint( PaintEventArgs e )
    {
      GraphicsPath Path = new GraphicsPath();
      Rectangle R = new Rectangle(10, 10, 50, 50);
      e.Graphics.DrawRectangle(Pens.Black,R);
      Path.AddRectangle(R);
      
//      PathGradientBrush B = new PathGradientBrush(Path.PathPoints); 
      PathGradientBrush B = new PathGradientBrush(Path.PathPoints, 
        WrapMode.Tile);
      Color[] c = { Color.Blue, Color.Aqua, Color.Red };

      B.CenterColor = Color.White;
      B.SurroundColors = c;

      //Small circle inside gradient path
      e.Graphics.FillEllipse(B, 15, 15, 30, 30);
      //Large circle outside gradient path
      e.Graphics.FillEllipse(B, 50, 50, 150, 150);
    }

    }
}