高级绘图

Code
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Diagnostics;

namespace 控件模拟别人的
{
    public partial class Form1 : Form
    {
        private RectangleF selectorRct = Rectangle.Empty;
        private int opacity = 200;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            //e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
            //DrawSelector(e);
        }

        private void DrawSelector(PaintEventArgs e)
        {
            selectorRct.X = this.Width/2;
            selectorRct.Y = this.Height/2;

            GraphicsPath gp = CreateRoundedRectangle(selectorRct, 100);

            Pen p=new Pen(Color.FromArgb(200,Color .Black));
            e.Graphics .DrawPath(p,gp);
            PathGradientBrush pgb=new PathGradientBrush(gp);

            Color[] surroundColor = new Color[] {
                Color.FromArgb(opacity, 227, 243, 255),
                Color.FromArgb(opacity, 189, 205, 233),
                Color.FromArgb(opacity, 103, 150, 161),
                Color.FromArgb(opacity, 76, 118, 146)};
            float[] positions = new float[] { 0f, .82f, .85f, 1.0f };
             
            ColorBlend blnd = new ColorBlend();
            blnd.Positions = positions;
            blnd.Colors = surroundColor;
            pgb.InterpolationColors = blnd;
            pgb.SurroundColors = surroundColor;

            e.Graphics.FillPath(pgb, gp);

            p.Dispose();
            gp.Dispose();
            pgb.Dispose();            
        }

        public static GraphicsPath CreateRoundedRectangle(RectangleF rct, int radius)
        {
            GraphicsPath gp = new GraphicsPath();
            PointF pt1 = new PointF(rct.X + radius, rct.Y);
            PointF pt2 = new PointF(rct.X + rct.Width - radius, rct.Y);
            RectangleF rct1 = new RectangleF(rct.X, rct.Y, radius, radius);

            gp.AddArc(rct1, 180f, 90f);
            gp.AddLine(pt1, pt2);

            rct1.Location = pt2;
            gp.AddArc(rct1, 270f, 90f);

            pt1 = new PointF(rct.X + rct.Width, rct.Y + radius);
            pt2 = new PointF(rct.X + rct.Width, rct.Y + rct.Height - radius);
            gp.AddLine(pt1, pt2);

            rct1.Location = new PointF(rct.X + rct.Width - radius, rct.Y + rct.Height - radius);
            gp.AddArc(rct1, 0f, 90f);

            pt1 = new PointF(rct.X + rct.Width - radius, rct.Y + rct.Height);
            pt2 = new PointF(rct.X + radius, rct.Y + rct.Height);
            gp.AddLine(pt1, pt2);

            rct1.Location = new PointF(rct.X, rct.Y + rct.Height - radius);
            gp.AddArc(rct1, 90f, 90f);

            gp.CloseFigure();

            return gp;
        }

        private void panel1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
            DrawSelector(e);
            //panel1.Refresh();          
        }
    }
}