ASP.NET AJAX MultiHandleSliderExtender - Slide by Year and Month

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Xml.Linq;
using System.Collections;
using System.Drawing;
using System.Web.UI.DataVisualization.Charting;
using System.Globalization;

public partial class _Default : System.Web.UI.Page
{
    protected static List<Range> lstSliderRange = null;
    Random rand = new Random();

    protected void Page_Load(object sender, EventArgs e)
    {
        Chart1.Click += new ImageMapEventHandler(Chart1_Click);

        PopulateSlider();

        if (!Page.IsPostBack)
        {
            //slider min and max value
            MultiHandleSliderExtender1.Minimum = 1;
            MultiHandleSliderExtender1.Maximum = int.Parse(lstSliderRange.Max(r => r.RowNumber).ToString());

            //hidden field
            rangeEnd.Value = MultiHandleSliderExtender1.Maximum.ToString();
            rangeStart.Value = MultiHandleSliderExtender1.Minimum.ToString();

            CreateArray();

            PopulateChart(int.Parse(rangeStart.Value), int.Parse(rangeEnd.Value));      
        }

        SetLabel();
    }

    void CreateArray()
    {
        foreach (Range r in lstSliderRange)
        {
            Page.ClientScript.RegisterArrayDeclaration("arrRange", "'"+r.Year +"--" + r.Month+"'");
        }
    }

    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        this.GridView1.PageIndex = e.NewPageIndex;
        PopulateGrid(ChartPostBackValue.Value);
    }

    void PopulateChart(int start, int end)
    {
        List<CarsList> lstCarsnTotal = new List<CarsList>();

        XDocument xmlDoc = XDocument.Load(Server.MapPath(Utilities.Instance.CarsListXMLPath));
        lstCarsnTotal = (from c in xmlDoc.Descendants("Car")
                         where (int)c.Attribute("YearMonth") >= GetRange(start) && (int)c.Attribute("YearMonth") <= GetRange(end)
                         group c by (string)c.Attribute("CarBrand") into g

                         select new CarsList
                         {
                             CarCount = g.Sum(c => (int)c.Attribute("Count")),
                             CarBrand = g.Key
                         }).ToList();

        #region chartRegion
        this.Chart1.Series[0].PostBackValue = "#AXISLABEL";

        Chart1.Series["Default"].SmartLabelStyle.Enabled = false;
        Chart1.Series["Default"].LabelAngle = -45;

        Chart1.Series["Default"].ChartType = SeriesChartType.Column;
        Chart1.Series["Default"].Points.DataBindXY(lstCarsnTotal, "CarBrand", lstCarsnTotal, "CarCount");

        Chart1.Series["Default"].IsXValueIndexed = true;
        Chart1.Series["Default"].IsVisibleInLegend = false;

        Chart1.ChartAreas["ChartArea1"].AxisX.Interval = 1;

        Chart1.ChartAreas["ChartArea1"].AxisX.LabelStyle.Angle = -45;

        Chart1.Series["Default"].IsValueShownAsLabel = true;
        Chart1.Series["Default"]["DrawingStyle"] = "Cylinder";

        Chart1.Series["Default"]["ShowMarkerLines"] = "true";
        Chart1.Series["Default"]["PointWidth"] = "0.9";

        // Set series visual attributes
        Chart1.Series["Default"].BackSecondaryColor = Color.Green;
        Chart1.Series["Default"].BackGradientStyle = GradientStyle.DiagonalLeft;

        Chart1.Series["Default"].BorderColor = Color.Black;
        Chart1.Series["Default"].BorderWidth = 2;
        Chart1.Series["Default"].BorderDashStyle = ChartDashStyle.Solid;

        Chart1.Series["Default"].ShadowOffset = 2;

        //remove HTML tags
        Chart1.Titles[0].Text = System.Text.RegularExpressions.Regex.Replace(
                    String.Format("Cars on Sesame Street {0} {1}", GetSliderText(start.ToString(), "s"),
                            GetSliderText(end.ToString(), "e")), @"<(.|\n)*?>", string.Empty);

        // Set Antialiasing mode
        Chart1.AntiAliasing = AntiAliasingStyles.All;
        Chart1.TextAntiAliasingQuality = TextAntiAliasingQuality.High;

        //set random colors
        for (int pointIndex = 0; pointIndex < Chart1.Series["Default"].Points.Count; pointIndex++)
        {
            Chart1.Series["Default"].Points[pointIndex].Color = GetRandomColor();
        }

        Chart1.Focus();
        #endregion
    }

    protected void Chart1_Click(object sender, ImageMapEventArgs e)
    {
        if (!GridView1.Visible)
        {
            GridView1.Visible = true;
        }
        //kept track of selected car type
        ChartPostBackValue.Value = e.PostBackValue;
        lblCarBrand.Text = "Car Brand: " + e.PostBackValue;

        PopulateGrid(e.PostBackValue);
        PopulateChart(int.Parse(rangeStart.Value), int.Parse(rangeEnd.Value));
    }

    void PopulateGrid(string strPostBavkVal)
    {
        List<CarsList> lstCarsnTotal = new List<CarsList>();

        XDocument xmlDoc = XDocument.Load(Server.MapPath(Utilities.Instance.CarsListXMLPath));
        lstCarsnTotal = (from c in xmlDoc.Descendants("Car")
                         where (int)c.Attribute("YearMonth") >= GetRange(int.Parse(rangeStart.Value))
                         && (int)c.Attribute("YearMonth") <= GetRange(int.Parse(rangeEnd.Value)) && (string)c.Attribute("CarBrand") == strPostBavkVal
                         select new CarsList
                         {
                             CarCount = (int)c.Attribute("Count"),
                             CarBrand = (string)c.Attribute("CarBrand"),
                             Date = (string)c.Attribute("Date")
                         }).ToList();

        GridView1.DataSource = lstCarsnTotal;
        GridView1.DataBind();
    }

    public Color GetRandomColor()
    {
        return Color.FromArgb(rand.Next(0, 256), rand.Next(0, 256), rand.Next(0, 256));
    }

    //set the slider start and end label
    void SetLabel()
    {
        string[] arrLabel = SliderRange(rangeStart.Value, rangeEnd.Value).Split("--".ToCharArray());
        lblStartRange.Text = arrLabel[0];
        lblEndRange.Text = arrLabel[2];
    }

    //get slider range
    void PopulateSlider()
    {
        //Cache the frequently used data
        if (Cache["Cache_lstSliderRange"] == null)
        {
            XDocument xmlDoc = XDocument.Load(Server.MapPath(Utilities.Instance.SliderRangeXMLPath));
            lstSliderRange = (from c in xmlDoc.Descendants("Range")
                              select new Range
                              {
                                  Month = (string)c.Attribute("Month"),
                                  Year = (string)c.Attribute("Year"),
                                  RowNumber = (int)c.Attribute("RowNumber")
                              }).ToList();

            Cache.Insert("Cache_lstSliderRange", lstSliderRange,
                new System.Web.Caching.CacheDependency(Server.MapPath(Utilities.Instance.SliderRangeXMLPath)));
        }
        else
        {
            lstSliderRange = Cache["Cache_lstSliderRange"] as List<Range>;
        }
    }

    [System.Web.Services.WebMethod]
    public static string SliderRange(string start, string end)
    {
        if (lstSliderRange != null)
        {
            return GetSliderText(start, "s") + "--" + GetSliderText(end, "e");
        }
        else
        {
            return "";
        }
    }

    //return YearMonth
    protected static int GetRange(int rn)
    {
        IEnumerable<Range> rangeText;

        rangeText = lstSliderRange.Where(r => r.RowNumber == rn)
            .Select(r => new Range
            {
                Year = r.Year,
                Month = r.Month
            });

        return int.Parse(rangeText.First().Year + rangeText.First().Month);
    }

    protected static string GetSliderText(string rn, string pos)
    {
        string strRangeText = string.Empty;
        IEnumerable<Range> rangeText;

        rangeText = lstSliderRange.Where(r => r.RowNumber == int.Parse(rn))
            .Select(r => new Range
            {
                Year = r.Year,
                Month = r.Month
            });

        if (pos == "s")
        {
            strRangeText = "<b>From</b> Year: " + rangeText.First().Year + " Month: " + rangeText.First().Month;
            return strRangeText;
        }
        else
        {
            strRangeText = "<b>To</b> Year: " + rangeText.First().Year + " Month: " + rangeText.First().Month;
            return strRangeText;
        }
    }

    protected void btnLoadChart_Click(object sender, EventArgs e)
    {
        // hide the gridview
        GridView1.Visible = false;
        //keep track of the range
        hdfTrackRangeStart.Value = rangeStart.Value;
        hdfTrackRangeEnd.Value = rangeEnd.Value;
        lblCarBrand.Text = String.Empty;
        UpdatePanel1.Update();
        PopulateChart(int.Parse(rangeStart.Value), int.Parse(rangeEnd.Value));
    }
}