创建饼形图之后如何改变各扇区颜色

//饼状图,统计不同角色的用户数量的百分比

    protected void Page_Load(object sender, EventArgs e)

    {

        //存储所有角色

        List<string> roles = new List<string>();

        //存储对应不同角色的用户数量

        List<int> userquantity_uniquerole = new List<int>();



        #region 数据库动态读出的数据赋给以上俩个List<int>变量

        string query_roles_sql = "select distinct role from user";

        try

        {

            MySqlConnection myConn = new MySqlConnection(conn_sql);

            myConn.Open();



            MySqlCommand myCommand = new MySqlCommand(query_roles_sql, myConn);

            //myCommand.ExecuteNonQuery();

            MySqlDataReader myReader = myCommand.ExecuteReader();

            

            while (myReader.Read())

            {

                roles.Add(myReader["role"].ToString());

                userquantity_uniquerole.Add(getCount(myReader["role"].ToString()));

            }



            myReader.Dispose();

            myCommand.Dispose();

            myConn.Close();

        }

        catch (MySqlException ee)

        {

            Console.Write("<script>alert(MySQL connection error:'" + ee.Message.ToString() + "')</script>");

        }

        #endregion



        string strDataName = "";

        string strData = "";



        //创建图表空间

        ChartSpace mychartSpace = new ChartSpace();

        mychartSpace.Border.Color = "White";

        //在图表空间内添加一个图表对象

        ChChart mychart = mychartSpace.Charts.Add(0);

        //设置每块饼的数据

        for (int i = 0; i < userquantity_uniquerole.Count(); i++)

        {

            strDataName += roles[i].ToString() + "\t";

            strData += userquantity_uniquerole[i].ToString() + "\t";

        }

        //设置图表类型，本例使用饼

        mychart.Type = ChartChartTypeEnum.chChartTypePie;

        //设置图表的一些属性

        //是否需要图例

        mychart.HasLegend = true;

        //是否需要主题

        mychart.HasTitle = true;

        //主题内容

        mychart.Title.Caption = "饼状图测试";

        mychart.Title.Font.Size = 10;

        mychart.Title.Font.Bold = false;

        mychart.Legend.Position = ChartLegendPositionEnum.chLegendPositionBottom;

        mychart.Legend.Interior.Color = "f9f9f9";

        mychart.Legend.Font.Size = 9;

        mychart.Legend.Border.Color = "White";



        //添加图表块

        mychart.SeriesCollection.Add(0);

        //设置图表块的属性

        //分类属性

        mychart.SeriesCollection[0].SetData(ChartDimensionsEnum.chDimCategories,

            (int)ChartSpecialDataSourcesEnum.chDataLiteral, strDataName);

        //值属性

        mychart.SeriesCollection[0].SetData(ChartDimensionsEnum.chDimValues,

            (int)ChartSpecialDataSourcesEnum.chDataLiteral, strData);

        for (int j = 0; j < mychart.SeriesCollection[0].Points.Count; j++)

        {

            mychart.SeriesCollection[0].Points[j].Border.Color = "White";

        }

        //显示百分比

        ChDataLabels mytb = mychart.SeriesCollection[0].DataLabelsCollection.Add();

        mytb.HasPercentage = true;

        //mytb.Border.Color　=　"White";

        mytb.HasValue = true;

        //生成图片

        mychartSpace.ExportPicture(Server.MapPath(".") + @"\chart\pie_chart.gif", "gif", 400, 400);

        //加载图片

        Image1.ImageUrl = "chart/pie_chart.gif" + "?temp=" + new Random().Next(1, 100) + "";

    }