ASP.NET系统用户权限设计

     图形的绘制涉及到的类并不是很多，如果要绘制图形，特别是这种数据源动态变化的图形，坐标位置的控制非常关键。
  这个Demo采用oracle数据库为数据源：

CREATE TABLE IVAN_TEST
(
  MAJOR  VARCHAR2(50),
  GRADE  NUMBER,
  ID     NUMBER(10)
)
Html中加入：

 <asp:Button ID="btnColumn" runat="server" Text="DrawColumn" OnClick="btnColumn_Click" /><br />
        <asp:Image ID="imgColumn" runat="server" />
CS:()
protected void btnColumn_Click(object sender, EventArgs e)
    ...{
        Bitmap img = new Bitmap(300,300);
        Graphics g = Graphics.FromImage(img);
         StringFormat drawFormat = new System.Drawing.StringFormat(StringFormatFlags.DirectionVertical);
        StringFormat drawFormat1 = new System.Drawing.StringFormat(StringFormatFlags.DisplayFormatControl);
        g.Clear(ColorTranslator.FromHtml("#F0F0F0"));
        g.DrawString("Student Grade Column Chart", new Font("Arial",1, FontStyle.Bold),Brushes.Black , 100, 0,drawFormat1);

        //get datasource
        string sql = "select * from ivan_test";
        DAL.ISDApp01 cDal = new DAL.ISDApp01();
        DataSet ds = cDal.ExecuteQuery(sql);

        for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
        ...{
            int grade = Convert.ToInt32(ds.Tables[0].Rows[i][1]);  //grade
            string Major = ds.Tables[0].Rows[i][0].ToString();

           //注意坐标的控制
            g.FillRectangle(new SolidBrush(GetColor(i)), (i * 35) + 15, 150 - grade, 20,
            grade+50 );

            g.DrawRectangle(new Pen(Color.Black), (i * 35) + 15, 150 - grade, 20,
            grade + 50);

            g.DrawString(Major, new Font("Arial", 12, FontStyle.Bold), Brushes.Red, (i * 35) + 20, 200,drawFormat);

            g.DrawString(grade.ToString(), new Font("Arial", 12, FontStyle.Bold), Brushes.Red, (i * 35) + 20, 130 - grade );

        }
         //show chart

        string Filepath = Server.MapPath("Images") + "//" + "Column.jpg?http://www.xvna.com";
        if (File.Exists(Filepath))
        ...{
            File.Delete(Filepath);
        }
        img.Save(Filepath, ImageFormat.Jpeg);
        img.Dispose();
        g.Dispose();
        this.imgColumn.ImageUrl = Filepath;
    }