C#.NET实现折线图

为了更好、更直观的看出统计的数据趋势，我们可以通过做折线图来实现。下面就介绍一个画折线图的例子：

注意添加引用 using System.Drawing.Imaging;   using System.Drawing;

   protected   void  Page_Load( object  sender, EventArgs e)
     ... {      
        string[] month = new string[12] ...{ "一月", "二月", "三月", "四月", "五月", "六月", "七月", "八月", "九月", "十月", "十一月", "十二月" };
        float[] d = new float[12] ...{ 20.5f, 60, 10.8f, 15.6f, 30, 70.9f, 50.3f, 30.7f, 70, 50.4f, 30.8f, 20 }; //图中的点的数据

        //画图初始化
        System.Drawing.Bitmap bmap = new System.Drawing.Bitmap(500, 500);
        Graphics gph = Graphics.FromImage(bmap);
        gph.Clear(Color.White);
        PointF cpt = new PointF(40, 420);//中心点
        PointF[] xpt = new PointF[3] ...{ new PointF(cpt.Y + 15, cpt.Y), new PointF(cpt.Y, cpt.Y - 8), new PointF(cpt.Y, cpt.Y + 8) };//x轴三角形
        PointF[] ypt = new PointF[3] ...{ new PointF(cpt.X, cpt.X - 15), new PointF(cpt.X - 8, cpt.X), new PointF(cpt.X + 8, cpt.X) };//y轴三角形
        gph.DrawString("某工厂某产品月生产量图表", new Font("宋体", 14), Brushes.Black, new PointF(cpt.X + 60, cpt.X));//图表标题

        //画x轴
        gph.DrawLine(Pens.Black, cpt.X, cpt.Y, cpt.Y, cpt.Y);
        gph.DrawPolygon(Pens.Black, xpt);
        gph.FillPolygon(new SolidBrush(Color.Black), xpt);
        gph.DrawString("月份", new Font("宋体", 12), Brushes.Black, new PointF(cpt.Y + 10, cpt.Y + 10));

        //画y轴
        gph.DrawLine(Pens.Black, cpt.X, cpt.Y, cpt.X, cpt.X);
        gph.DrawPolygon(Pens.Black, ypt);
        gph.FillPolygon(new SolidBrush(Color.Black), ypt);
        gph.DrawString("单位(万)", new Font("宋体", 12), Brushes.Black, new PointF(0, 7));
        for (int i = 1; i <= 12; i++)
        ...{
            //画y轴刻度
            if (i < 11)
            ...{
                gph.DrawString(Convert.ToString(i * 10), new Font("宋体", 11), Brushes.Black, new PointF(cpt.X - 30, cpt.Y - i * 30 - 6));
                gph.DrawLine(Pens.Black, cpt.X - 3, cpt.Y - i * 30, cpt.X, cpt.Y - i * 30);
            }
            //画x轴项目
            gph.DrawString(month[i - 1].Substring(0, 1), new Font("宋体", 11), Brushes.Black, new PointF(cpt.X + i * 30 - 5, cpt.Y + 5));
            gph.DrawString(month[i - 1].Substring(1, 1), new Font("宋体", 11), Brushes.Black, new PointF(cpt.X + i * 30 - 5, cpt.Y + 20));
            if (month[i - 1].Length > 2) gph.DrawString(month[i - 1].Substring(2, 1), new Font("宋体", 11), Brushes.Black, new PointF(cpt.X + i * 30 - 5, cpt.Y + 35));
            //画点
            gph.DrawEllipse(Pens.Black, cpt.X + i * 30 - 1.5f, cpt.Y - d[i - 1] * 3 - 1.5f, 3, 3);
            gph.FillEllipse(new SolidBrush(Color.Black), cpt.X + i * 30 - 1.5f, cpt.Y - d[i - 1] * 3 - 1.5f, 3, 3);
            //画数值
            gph.DrawString(d[i - 1].ToString(), new Font("宋体", 11), Brushes.Black, new PointF(cpt.X + i * 30, cpt.Y - d[i - 1] * 3));
            //画折线
            if (i > 1) gph.DrawLine(Pens.Red, cpt.X + (i - 1) * 30, cpt.Y - d[i - 2] * 3, cpt.X + i * 30, cpt.Y - d[i - 1] * 3);

        }

        //输出到浏览器
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        bmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        Response.ClearContent();
        Response.ContentType = "image/Gif";
        Response.BinaryWrite(ms.ToArray());
        gph.Dispose();
        bmap.Dispose();
}

显示效果如下：