為控制項畫背景

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;

namespace DevDistrict.Sample
{
 public class GradientPanel : System.Windows.Forms.Panel
 {
  protected override void OnPaint(PaintEventArgs e)
  {
   base.OnPaint (e);

   Graphics g = e.Graphics;

   g.SmoothingMode = SmoothingMode.HighQuality;
   GraphicsPath gPath = new GraphicsPath();

   Rectangle r = new Rectangle(0,0,this.Width,this.Height);
   gPath.AddRectangle(r);

   LinearGradientBrush lb = new LinearGradientBrush(r,Color.White,Color.Blue,LinearGradientMode.Vertical);

   g.FillPath(lb,gPath);
  }
 }
}