Winform绘制圆形图

        private void Form_Load(object sender, EventArgs e)
        {
            PictureBox pic = new PictureBox();
            pic.Name = "pic1";
            pic.Size = new System.Drawing.Size(17, 17);
            pic.BackgroundImage = GetRoundPic(Color.Red);
            //pic.Paint += DrawPic_Paint;
            this.Controls.Add(pic);
        }
        /// <summary>
        /// 绘制圆形图，并赋值BackgroundImage
        /// </summary>
        public Bitmap GetRoundPic(Color color)
        {
            Size size = new Size(16, 16);
            Bitmap bitmap = new Bitmap(size.Width, size.Height);
            using (Graphics g = Graphics.FromImage(bitmap))
            {
                using (Brush br = new SolidBrush(color))
                {
                    g.SmoothingMode = SmoothingMode.AntiAlias;
                    g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    g.CompositingQuality = CompositingQuality.HighQuality;
                    g.FillEllipse(br, new Rectangle(Point.Empty, size));
                    //Pen pen = new Pen(Color.Red);
                    //g.DrawEllipse(pen, new Rectangle(Point.Empty, size));
                }
            }
            return bitmap;
        }
        /// <summary>
        /// 重绘圆形图
        /// </summary>
        private void DrawPic_Paint(object sender, PaintEventArgs e)
        {
            int ntemp = 2;
            //根据样本类型，对应颜色
            Brush brush = new SolidBrush(Color.Red);
            Pen pen = new Pen(brush);
            e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
            e.Graphics.DrawEllipse(pen, new RectangleF(e.ClipRectangle.Left + ntemp,
            e.ClipRectangle.Top +
            ntemp, e.ClipRectangle.Width - (2 * ntemp),
            e.ClipRectangle.Height - (2 * ntemp)));
            //实心填充
            Rectangle r = new Rectangle(e.ClipRectangle.Left + ntemp, e.ClipRectangle.Top +
            ntemp, e.ClipRectangle.Width - (2 * ntemp), e.ClipRectangle.Height - (2 * ntemp));
            e.Graphics.DrawEllipse(pen, r);
            e.Graphics.FillEllipse(brush, r);
        }