WinForm绘制圆角的方法

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Drawing.Drawing2D;
namespace AppStartSample
{
 public partial class Form3 : Form
 {
  public Form3()
  {
   InitializeComponent();
  }
  private void button1_Click(object sender, EventArgs e)
  {
  }
  private void button2_Click(object sender, EventArgs e)
  {
  }
  public void SetWindowRegion()
  {
   System.Drawing.Drawing2D.GraphicsPath FormPath;
   FormPath = new System.Drawing.Drawing2D.GraphicsPath();
   Rectangle rect = new Rectangle(0, 22, this.Width, this.Height - 22);//
   FormPath = GetRoundedRectPath(rect, 30);
   this.Region = new Region(FormPath);
  }
  private GraphicsPath GetRoundedRectPath(Rectangle rect, int radius)
  {
   int diameter = radius;
   Rectangle arcRect = new Rectangle(rect.Location, new Size(diameter, diameter));
   GraphicsPath path = new GraphicsPath();
   // 左上角  
   path.AddArc(arcRect, 180, 90);
   // 右上角  
   arcRect.X = rect.Right - diameter;
   path.AddArc(arcRect, 270, 90);
   // 右下角  
   arcRect.Y = rect.Bottom - 0;
   path.AddArc(arcRect, 0, 90);
   // 左下角  
   arcRect.X = rect.Left;
   path.AddArc(arcRect, 90, 90);
   path.CloseFigure();
   return path;
  }
  protected override void OnResize(System.EventArgs e)
  {
   this.Region = null;
   SetWindowRegion();
  }
 }
}