asp.net 曲线图

 public void draw(DataTable dt)
    {
        //取得记录数量
        int count = dt.Rows.Count;
        //记算图表宽度
        int wd = 80 + 20 * (count - 1);
        //设置最小宽度为800
        if (wd < 600) wd = 600;
        //生成Bitmap对像
        Bitmap img = new Bitmap(wd, 400);
        //生成绘图对像
        Graphics g = Graphics.FromImage(img);
        //定义黑色画笔
        Pen Bp = new Pen(Color.Black);
        //定义红色画笔
        Pen Rp = new Pen(Color.Red);
        //定义银灰色画笔
        Pen Sp = new Pen(Color.Silver);
        //定义大标题字体
        Font Bfont = new Font("Arial", 12, FontStyle.Bold);
        //定义一般字体
        Font font = new Font("Arial", 6);
        //定义大点的字体
        Font Tfont = new Font("Arial", 9);
        //定义横坐标间隔，(最佳值是总宽度-留空宽度[左右侧都需要])/(记录数量-1)
        int xSpace = (wd - 100) / (count - 1);
        //定义纵坐标间隔,不能随便修改，跟高度和横坐标线的条数有关，最佳值=(绘图的高度-上面留空-下面留空)
        int ySpace = 30;
        //纵坐标最大值和间隔值
        int yMaxValue = 30;
        //绘制底色
        g.DrawRectangle(new Pen(Color.White, 400), 0, 0, img.Width, img.Height);
        //定义黑色过渡型笔刷
        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Black, Color.Black, 1.2F, true);
        //定义蓝色过渡型笔刷
        LinearGradientBrush Bluebrush = new LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Blue, Color.Blue, 1.2F, true);
        //绘制大标题
        g.DrawString("测试曲线图", Bfont, brush, 40, 5);

        //绘制信息简报
        string info = "  曲线图生成时间：" + DateTime.Now.ToString();
        g.DrawString(info, Tfont, Bluebrush, 40, 25);
        //绘制图片边框
        g.DrawRectangle(Bp, 0, 0, img.Width - 1, img.Height - 1);

        //绘制竖坐标轴
        g.DrawLine(Bp, 40, 55, 40, 360);
        //绘制横坐标轴 x2的60是右侧空出部分
        g.DrawLine(Bp, 40, 360, 60 + xSpace * (count - 1), 360);

        //绘制竖坐标标题
        g.DrawString("测试值", Tfont, brush, 5, 40);
        //绘制横坐标标题
        g.DrawString("测试时间", Tfont, brush, 40, 385);

        //绘制竖坐标线
        for (int i = 0; i < count; i++)
        {
            g.DrawLine(Sp, 40 + xSpace * i, 60, 40 + xSpace * i, 360);
        }
        //绘制时间轴坐标标签
        for (int i = 0; i < count; i++)
        {
            string st = Convert.ToDateTime(dt.Rows[i]["AddTime"]).ToString("MM:dd");
            g.DrawString(st, font, brush, 30 + xSpace * i, 370);
        }

        //绘制横坐标线
        for (int i = 0; i < 10; i++)
        {
            g.DrawLine(Sp, 40, 60 + ySpace * i, 40 + xSpace * (count - 1), 60 + ySpace * i);
            //横坐标轴的值间隔是最大值除以间隔数
            int s = yMaxValue - i * (yMaxValue / 10);
            //绘制发送量轴坐标标签
            g.DrawString(s.ToString(), font, brush, 10, 60 + ySpace * i);
        }

        //定义纵坐标单位数值=纵坐标最大值/标量最大值（300/30）
        int yAveValue = 10;
        //定义曲线转折点
        Point[] p = new Point[count];
        for (int i = 0; i < count; i++)
        {
            p[i].X = 40 + xSpace * i;
            p[i].Y = 360 - Convert.ToInt32(dt.Rows[i]["Number"]) * yAveValue;
        }
        //绘制折线图
        //g.DrawLines(Rp, p);
        //绘制曲线图
        //g.DrawCurve(Rp, p);
        //绘制自定义张力的曲线图（0.5F是张力值，默认就是这个值）
        g.DrawCurve(Rp, p,0.5F);

        //当需要在一个图里绘制多条曲线的时候，就多定义个point数组，然后画出来就可以了。

        for (int i = 0; i < count; i++)
        {
            //绘制发送记录点的发送量
            g.DrawString(dt.Rows[i]["RoleName"].ToString(), font, Bluebrush, p[i].X, p[i].Y - 10);
            //绘制发送记录点
            g.DrawRectangle(Rp, p[i].X - 1, p[i].Y - 1, 2, 2);
        }

        //保存绘制的图片
        MemoryStream stream = new MemoryStream();
        img.Save(stream, ImageFormat.Jpeg);
        //图片输出
        Response.Clear();
        Response.ContentType = "image/jpeg";
        Response.BinaryWrite(stream.ToArray());
    }