owc画折线图有关问题

using System;using System.Data;using System.Data.SqlClient;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;using System.Drawing;using System.Drawing.Imaging;public partial class _Default : System.Web.UI.Page{    int x = 0;    int y = 0;    int x_1_v = 0;    int y_1_v = 0;    int x_df = 0;    int y_df = 0;    int width = 0;    int height = 0;    double y_max = 0;      protected void Page_Load(object sender, EventArgs e)    {        CreateImage();           }    void CreateImage()    {        int id = int.Parse(Request.QueryString["id"].ToString());        _Init(100, 100, 40*id, 25, 24, 10);        Bitmap image = new Bitmap(width, height);        Graphics g = Graphics.FromImage(image);        Pen pen1 = new Pen(Color.Turquoise, 1);        Pen pen2 = new Pen(System.Drawing.Color.DimGray, 1);        g.FillRectangle(Brushes.Black, 0, 0, width, height);        CreateMap(g, pen1, pen2);        String[] m = { "100", "90", "80", "70", "60", "50", "40", "30", "20", "10" };        Font font = new Font("Verdana", 12);        Brush b = Brushes.PowderBlue;        Creat_XY_Values(m, b, font, g);                y_max = double.Parse(m[0]);        DataTable dt = GetTable();        Pen mypen = new Pen(System.Drawing.Color.MediumSpringGreen, 1);        Brush bb = Brushes.Chartreuse;        Font font_line = new System.Drawing.Font("Arial", 10, FontStyle.Bold);        DrawLine(dt, "value", "time", font_line, bb, mypen, g);        System.IO.MemoryStream ms = new System.IO.MemoryStream();        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);        Response.ClearContent();        Response.ContentType = "image/Jpeg";        Response.BinaryWrite(ms.ToArray());        }    void DrawLine(DataTable dt, string str_y, string str_x, Font font, Brush brush, Pen pen, Graphics g)    {        bool b = true;        Point[] point = new Point[dt.Rows.Count];        for (int i = 0; i < dt.Rows.Count; i++)        {            if (i != 0)            {                if (double.Parse(dt.Rows[i][str_y].ToString()) != 0)                {                    double xx = ChangeTime(dt.Rows[i][str_x].ToString());                    //double xx = double.Parse(dt.Rows[i][str_x].ToString());                    point[i] = Points(xx, int.Parse(dt.Rows[i][str_y].ToString()));                    //g.DrawString(dt.Rows[i][str_y].ToString(), font, brush, point[i].X - 10, point[i].Y - 20);                    if (b)                    {                        g.DrawLine(pen, point[i - 1], point[i]);                    }                    else                    { b = true; }                }                else                {                    double xx = ChangeTime(dt.Rows[i][str_x].ToString());                    //double xx = double.Parse(dt.Rows[i][str_x].ToString());                    point[i] = Points(xx, int.Parse(dt.Rows[i][str_y].ToString()));                    b = false;                }            }            else            {                double xx = ChangeTime(dt.Rows[i][str_x].ToString());                //double xx = double.Parse(dt.Rows[i][str_x].ToString());                point[i] = Points(xx, int.Parse(dt.Rows[i][str_y].ToString()));            }        }    }    Point Points(double _x, int _y)    {        Point p = new Point();        p.X = (int)(x + x_1_v * _x);        p.Y = (int)(y + y_1_v * y_df - (_y * (y_1_v * y_df / y_max)));        return p;    }    double ChangeTime(string time)    {        string[] s = time.Split(':');        int x = int.Parse(s[0].ToString());        double ff = int.Parse(s[1].ToString());        double mm = int.Parse(s[2].ToString());        double f = (ff * 60 + mm) / 3600;        double xx = x + f;        return xx;    }    void _Init(int _x, int _y, int _x_1_v, int _y_1_v, int _x_df, int _y_df)    {        x = _x;        y = _y;        x_1_v = _x_1_v;        y_1_v = _y_1_v;        x_df = _x_df;        y_df = _y_df;        width = x + x_1_v * x_df + 100;        height = y + y_1_v * y_df + 100;    }    void CreateMap(Graphics g, Pen pen1, Pen pen2)    {        int _x = x;        int _y = y;        //X轴网线        for (int i = 0; i <= x_df; i++)        {            if (i == 0 || i == x_df)                g.DrawLine(pen1, _x, y, _x, y + y_1_v * y_df);            else                g.DrawLine(pen2, _x, y, _x, y + y_1_v * y_df);            _x += x_1_v;        }        //Y轴网线        for (int j = 0; j <= y_df; j++)        {            if (j == 0 || j == y_df)                g.DrawLine(pen1, x, _y, x + x_1_v * x_df, _y);            else                g.DrawLine(pen2, x, _y, x + x_1_v * x_df, _y);            _y += y_1_v;        }    }    void Creat_XY_Values(string[] Y_Values, Brush b, Font font, Graphics g)    {        int _x = x - 10;        int _y = y - 10;        for (int i = 0; i <= x_df; i++)        {            g.DrawString(i.ToString(), font, b, _x, y + y_1_v * y_df);            _x += x_1_v;        }        for (int j = 0; j < Y_Values.Length; j++)        {            g.DrawString(Y_Values[j], font, b, x - 11 * Y_Values[j].Length, _y);            _y += y_1_v;        }    }    DataTable GetTable()    {        SqlConnection Con = new SqlConnection("Server=(Local);Database=test;Uid=sa;Pwd=rose");        Con.Open();        string cmdtxt2 = "select * from test_2";        SqlDataAdapter da = new SqlDataAdapter(cmdtxt2, Con);        DataSet ds = new DataSet();        da.Fill(ds, "Result");        DataTable dt = ds.Tables["Result"];        return dt;    }}