VS Chart ArrowAnnotation

 private void Form1_Load(object sender, EventArgs e)
        {
            //清除默认的series
            chart1.Series.Clear();
            //ChartArea area1 = new ChartArea("ChartArea1");
            //chart1.ChartAreas.Add(area1);
            chart1.ChartAreas[0].Axes[0].MajorGrid.Enabled = false; //X轴上网格
            chart1.ChartAreas[0].Axes[1].MajorGrid.Enabled = false; //y轴上网格
            chart1.ChartAreas[0].Axes[0].MajorTickMark.Enabled = false; // x轴上突出的小点
            chart1.ChartAreas[0].Axes[1].MajorTickMark.Enabled = false; // y轴上突出的小点
            chart1.ChartAreas[0].Axes[0].ArrowStyle = AxisArrowStyle.SharpTriangle;
            chart1.ChartAreas[0].Axes[1].ArrowStyle = AxisArrowStyle.SharpTriangle;
            chart1.ChartAreas[0].Axes[0].Title = "分钟";
            chart1.ChartAreas[0].Axes[1].Title = "温度";
            chart1.ChartAreas[0].Axes[0].TitleAlignment = StringAlignment.Far;
            chart1.ChartAreas[0].Axes[1].TitleAlignment = StringAlignment.Far;

            Series Strength = new Series("");
            Strength.ChartType = SeriesChartType.Line;
            //Strength.IsValueShownAsLabel = true;
            Strength.Points.AddXY(10, 10);
            Strength.Points.AddXY(20, 10);
            chart1.Series.Add(Strength);
            chart1.Series[0].Color = Color.Black;

            ArrowAnnotation ann = new ArrowAnnotation();

            //注释锚点(起点)--------------无法自定义锚点--------------
            ann.AnchorDataPoint = chart1.Series[0].Points[0]; //new DataPoint(20,5)

            //这两项用于设置注释终点位置
            ann.Height = 20;        //注释垂直高度
            ann.Width = 15;         //注释终点相对锚点左右移动距离

            ann.ArrowSize = 1;
            ann.BackColor = Color.Black;
            chart1.Annotations.Add(ann);
        }