public void SetShowConnectStatus(Label lbl, bool isOk)

        {

            lbl.Text = "";

            Graphics gra = lbl.CreateGraphics();

            gra.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

            Color c = isOk ? Color.Green : Color.Red;

            Brush bush = new SolidBrush(c);//填充的颜色

            gra.FillEllipse(bush, , , lbl.Width / , lbl.Width / );

        }

  private bool isRotaryConnectOK = false;

        private void button1_Click(object sender, EventArgs e)

        {

            isRotaryConnectOK =!isRotaryConnectOK;

            lblRotaryConnectStatus.Invalidate();

        }

        private void lblRotaryConnectStatus_Paint(object sender, PaintEventArgs e)

        {

            Graphics gp = e.Graphics;
　　　　　　　gp.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

            Color c = isRotaryConnectOK ? Color.Lime : Color.Red;

            SolidBrush s = new SolidBrush(c);

            gp.FillEllipse(s, , , lblRotaryConnectStatus.Width/, lblRotaryConnectStatus.Width / );

        }