"One size fits all" solution for freezing a Grid's header rows, why not?

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Globalization;
using System.Text;
using System.Collections.Generic;

public partial class FrozenGridHeader_Solution3 : System.Web.UI.Page
{
    #region Variables
    private string[] _dateFormats = { "dd/MM/yyyy", "yyyyMMdd" };
    private static DataProvider _controller;
    /// <summary>
    /// Stores the identifications of buttons.
    /// <para>Will be used to enable/disable all buttons.</para>
    /// </summary>
    System.Collections.Generic.LinkedList<String> _buttons;
    /// <summary>
    /// Number of visible columns
    /// </summary>
    private int _VisibleColumns = -1;
    private static DateTime? _from;
    private static DateTime? _to;
    #endregion
    #region Properties
    /// <summary>
    /// Number of visible columns
    /// </summary>
    private int VisibleColumns
    {
        get
        {
            if (_VisibleColumns == -1)
            {
                _VisibleColumns = 0;
                for (int i = 0; i < gridOrders.Columns.Count; i++)
                {
                    if (gridOrders.Columns[i].Visible) _VisibleColumns++;
                }
            }
            return _VisibleColumns;
        }
    }
    #endregion
    #region Page Events
    protected void Page_Init(object sender, EventArgs e)
    {
        btnSearch.Click += new EventHandler(btnSearch_Click);
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        PrepareExpandableLines();
        SetupGridHeaderFreezing();
    }

    private void SetupGridHeaderFreezing()
    {
        HeaderFreezeParameters parentGridPara = new HeaderFreezeParameters();
        parentGridPara.GridCss_Class = "gridview_style";
        parentGridPara.HeaderRowOnSight_CssClass = "parentgrid_header_row";
        parentGridPara.FreezingPosition = 0; //Freeze table at the top of browser
        parentGridPara.ShowTableFreezingIcon = true; //Show the freezing icon

        HeaderFreezeParameters childGridPara = new HeaderFreezeParameters();
        childGridPara.GridCss_Class = "childgridview_style";
        childGridPara.HeaderRowOnSight_CssClass = "HeaderRowOnSight";
        childGridPara.HeaderRowOutOfSight_CssClass = "HeaderRowOutOfSight";
        childGridPara.FreezingPosition = 80; //80 is the height of header rows of parent grid. Child grid will freeze at the point which is under the top of browser as "80px".
        childGridPara.ShowTableFreezingIcon = true;

        List<HeaderFreezeParameters> objGridHeaderFreezeSettingList = new List<HeaderFreezeParameters>();
        objGridHeaderFreezeSettingList.Add(parentGridPara);
        objGridHeaderFreezeSettingList.Add(childGridPara);

        GridHelper.FreezeTableHeader(objGridHeaderFreezeSettingList);
    }

    /// <summary>
    /// Releases allocated memory
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void Page_UnLoad(object sender, EventArgs e)
    {
        if (_controller != null)
        {
            _controller.Dispose();
            _controller = null;
        }
    }
    #endregion
    #region Grid Events
    /// <summary>
    /// Function : AddMergedCells
    /// Purpose: Adds merged cell in the header
    /// </summary>
    /// <param name="objgridviewrow"></param>
    /// <param name="objtablecell"></param>
    /// <param name="colspan"></param>
    /// <param name="celltext"></param>
    private static void AddMergedCells(GridViewRow objgridviewrow, TableCell objtablecell, int colspan, string celltext)
    {
        objtablecell.ColumnSpan = colspan;
        if(celltext != "")
            objtablecell.Text = celltext;

        objgridviewrow.Cells.Add(objtablecell);
    }

    protected void gridOrders_RowCreated(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e) 
    {
        if (e.Row.RowType == DataControlRowType.Header)
        {
            //e.Row.Cells[0].RowSpan = 2;
            //e.Row.Cells[1].RowSpan = 2;
            //e.Row.Cells[2].RowSpan = 2;
            //e.Row.Cells[3].RowSpan = 2;
            //e.Row.Cells[4].RowSpan = 2;

            ////TableCell mergeCell = new TableCell();
            ////mergeCell.Text = "Ship Information";
            ////mergeCell.ColumnSpan = 2;
            //e.Row.Cells[5].ColumnSpan = 2;

            ////Creating a gridview row object
            //GridViewRow objgridviewrow = new GridVieRow(1, 0, DataControlRowType.Header, DataControlRowState.Insert);

            ////Creating a table cell object
            //TableCell objtablecell;
            //objtablecell = e.Row.Cells[6];
            //AddMergedCells(objgridviewrow, objtablecell, 1);
            ////e.Row.Cells.RemoveAt(6);

            //objtablecell = e.Row.Cells[7];
            //AddMergedCells(objgridviewrow, objtablecell, 1);
            ////e.Row.Cells.RemoveAt(7);

            //e.Row.Cells[6].RowSpan = 2;
            //e.Row.Cells[7].RowSpan = 2;

            //gridOrders.Controls[0].Controls.AddAt(0, objgridviewrow);

            //Creating a gridview row object
            GridViewRow objgridviewrow = new GridViewRow(1, 0, DataControlRowType.Header, DataControlRowState.Insert);
            objgridviewrow.CssClass = "parentgrid_header_row";
            
            //Creating a table cell object
            TableCell objtablecell = new TableHeaderCell();
            objtablecell.RowSpan = 2;
            objtablecell.Text = e.Row.Cells[0].Text;
            objtablecell.ApplyStyle(e.Row.Cells[0].ControlStyle);
            AddMergedCells(objgridviewrow, objtablecell, 1, "");

            objtablecell = new TableHeaderCell();
            objtablecell.RowSpan = 2;
            objtablecell.Text = e.Row.Cells[1].Text;
            objtablecell.ApplyStyle(e.Row.Cells[0].ControlStyle);
            AddMergedCells(objgridviewrow, objtablecell, 1, "");

            objtablecell = new TableHeaderCell();
            objtablecell.ApplyStyle(e.Row.Cells[0].ControlStyle);
            AddMergedCells(objgridviewrow, objtablecell, 3, "Basic Information");

            objtablecell = new TableHeaderCell();
            objtablecell.ApplyStyle(e.Row.Cells[0].ControlStyle);
            AddMergedCells(objgridviewrow, objtablecell, 2, "Ship Information");

            objtablecell = new TableHeaderCell();
            objtablecell.RowSpan = 2;
            objtablecell.Text = e.Row.Cells[7].Text;
            objtablecell.ApplyStyle(e.Row.Cells[0].ControlStyle);
            AddMergedCells(objgridviewrow, objtablecell, 1, "");

            objtablecell = new TableHeaderCell();
            objtablecell.RowSpan = 2;
            objtablecell.ApplyStyle(e.Row.Cells[0].ControlStyle);
            AddMergedCells(objgridviewrow, objtablecell, 1, "");

            gridOrders.Controls[0].Controls.AddAt(0, objgridviewrow);
            e.Row.Cells.RemoveAt(0); //Remove the first column
            e.Row.Cells.RemoveAt(0); //Remove the second column
            e.Row.Cells.RemoveAt(5); //Remove the 7th column
            e.Row.Cells.RemoveAt(5); //Remove the 8th column
        }

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            Label lblRowNo = (Label)(e.Row.Cells[0].Controls[0]);

            //Set Label text equal to the rowIndex +1 
            lblRowNo.Text = (e.Row.RowIndex + 1).ToString();
        }
    }

    /// <summary>
    /// Called after the main grid was bound
    /// <para>Will create a Javascrip array, used to enable/disable the buttons</para>
    /// <para>See function EnableExpandButtons in ExpandPanel.js</para>
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void gridOrders_DataBound(object sender, EventArgs e)
    {
        if (_buttons != null && _buttons.Count > 0)
        {
            foreach (string element in _buttons)
            {
                ScriptManager.RegisterArrayDeclaration(
                    this.Page,
                    "ExpandButtons", // The array's name
                    String.Format(CultureInfo.InvariantCulture, "'{0}'", element));  // The button ID
            }
        }

        //String arrValue = "\"10284\", \"11077\", \"10251\"";
        ScriptManager.RegisterArrayDeclaration(this, "amoutCells", _arrAmountCells);

        //Re setup Freezing function
        //SetupFrozenGridHeaderRow();
        SetupGridHeaderFreezing();
    }

    private string _arrAmountCells = "";
    //private string[] _arrCellWidth = new string[20];
    /// <summary>
    /// Called for each row of the main grid, calls a method to prepare the details
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void gridOrders_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType != DataControlRowType.DataRow)
            return;

        try
        {
            //if (e.Row.RowIndex == 0)
            //{
            //    for (int j = 0; j < e.Row.Cells.Count; j++)
            //    {
            //        _arrCellWidth[j] = e.Row.Cells[j].Style["width"];
            //    }
            //}

            //if (e.Row.RowIndex == 1)
            //{
            //    for (int j = 0; j < e.Row.Cells.Count; j++)
            //    {
            //        e.Row.Cells[j].Style.Add("width", _arrCellWidth[j]);
            //    }
            //}

            Order orderRow = e.Row.DataItem as Order;
            GridViewRow gridRow = e.Row;
            
            Label lblOrderAmount = gridRow.FindControl("lblOrderAmount") as Label;
            _arrAmountCells = string.Format("{0}\"{1}:{2}\"", (_arrAmountCells == "" ? "" : _arrAmountCells + ","), lblOrderAmount.ClientID, orderRow.OrderID);
            lblOrderAmount.ID = orderRow.OrderID.ToString();
            lblOrderAmount.Text = String.Format("{0:#,##0;($#,##0);Zero}", _controller.SumOrderAmount(orderRow.OrderID));

            BuildNestedPanel(gridRow, orderRow);
        }
        catch (System.Exception ex)
        {
            ShowErrorMessage(ex.Message);
        }
    }
    #endregion
    #region ObjectDataSource Events
    /// <summary>
    /// Instantiates the business logic layer object, in order to fill the main grid
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void odsOrders_ObjectCreating(object sender, ObjectDataSourceEventArgs e)
    {
        try
        {
            _controller = new DataProvider();

            e.ObjectInstance = _controller;
        }
        catch (System.Exception ex)
        {
            ShowErrorMessage(ex.Message);
        }
    }

    /// <summary>
    /// Select simulated or data base stored data
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void odsOrders_Selecting(object sender, ObjectDataSourceSelectingEventArgs e)
    {
        btnSearch_Click(null, null);

        if (e.ExecutingSelectCount) return;

        e.InputParameters["from"] = _from;
        e.InputParameters["to"] = _to;
    }

    /// <summary>
    /// This method is called when the object odsStores releases memory used by the business logic layer object.
    /// <para>If some error was found when reading from database, this method will show the error message.</para>
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected void odsOrders_ObjectDisposing(object sender, ObjectDataSourceDisposingEventArgs e)
    {
        DataProvider controller = e.ObjectInstance as DataProvider;

        if (controller != null && controller.Error)
        {
            ShowErrorMessage(controller.Exception);
            gridOrders.Visible = false;
        }

        e.Cancel = true;
    }
    #endregion
    #region Control Events
    protected void btnSearch_Click(object sender, EventArgs e)
    {
        try
        {
            //Parameters Handling:
            //Parse parameters and pass on to the underlying ObjectDataSource
            txtFromDate.Text = txtFromDate.Text.Replace("__/__/____", "");
            txtToDate.Text = txtToDate.Text.Replace("__/__/____", "");

            if (string.IsNullOrEmpty(txtFromDate.Text))
                _from = null;
            else
                _from = DateTime.ParseExact(txtFromDate.Text, _dateFormats, CultureInfo.CurrentCulture, DateTimeStyles.None);

            if (string.IsNullOrEmpty(txtToDate.Text))
                _to = null;
            else
                _to = DateTime.ParseExact(txtToDate.Text, _dateFormats, CultureInfo.CurrentCulture, DateTimeStyles.None);
            //End Of Parameters Handling

            PrepareExpandableLines();
        }
        catch (System.Exception ex)
        {
            ShowErrorMessage(ex.Message);
        }
    }
    #endregion
    #region Private Methods
    #region Dynamically populate data on demand
    /// <summary>
    /// Register the script to expand/contract details in order to show order details
    /// </summary>
    private void PrepareExpandableLines()
    {
        // First, handle some specifics from Firefox
        // Reference : IE/Firefox show/hide/colspan
        //             http://forums.codewalkers.com/client-side-things-82/ie-firefox-show-hide-colspan-902435.html

        string StyleDisplayBlock = "block";

        if (this.Request.Browser.Browser.ToLower() == "firefox")
        {
            StyleDisplayBlock = "table-row";
        }
        
        //Added by Henry Truong, 2012/10/30
        if (Request.UserAgent.ToLower().IndexOf("chrome") > 0)
        {
            StyleDisplayBlock = "table-row";
        }

        string js = String.Format(CultureInfo.InvariantCulture,
            "var StyleDisplayBlock = '{0}';\n;"+
            "var ExpandableLines = '{1}';\n",
            StyleDisplayBlock, pnlExpandableLines.ClientID);

        ScriptManager.RegisterClientScriptBlock(this.Page, this.Page.GetType(), "StyleDisplayBlock", js, true);

        // Then, include the script
        ScriptManager.RegisterClientScriptInclude(
            this.Page,
            this.Page.GetType(),
            "expand_models",
            "JS/ExpandPanel.js");
    }

    /// <summary>
    /// Builds a string to populate the expanded line with the models
    /// </summary>
    /// <param name="contextKey">CustomerId + radSimulatedData.Checked, separated by '-'</param>
    /// <returns>HTML table filled with drilled down data</returns>
    [System.Web.Services.WebMethod(CacheDuration = 45, Description = "Get data")]
    [System.Web.Script.Services.ScriptMethod]   
    public static string DataDrillDownService(string contextKey)
    {
#if DEBUG
            // Small delay to provide time to show 'loading.gif'
            System.Threading.Thread.Sleep(1000);
#endif

        StringBuilder sb = new StringBuilder();

        System.Collections.Generic.List<OrderDetail> objOrderDetails = null;

        // Extracts OrderID and 'chkCachedData.Checked' from the context key

        string[] keys = contextKey.Split('-');

        bool cachedData = (keys[1][0] == '1');

        int orderID = 0;

        bool hasError = false;

        if (!Int32.TryParse(keys[0], out orderID))
        {
            // TODO: Error LOG
            hasError = true;
            sb.Append("<span class=\"error-models\">ERROR : Can not load the detail data</span>");
        }
        else
        {
            try
            {
                objOrderDetails = (System.Collections.Generic.List<OrderDetail>)(new DataProvider()).GetOrderDetails(orderID);
            }
            catch (System.Exception ex)
            {
                // TODO: Error LOG
                hasError = true;
                sb.Append("<span class=\"error-models\">ERROR : Can not get the data. Details: " + ex.Message + "</span>");
            }

            if (!hasError)
            {
                if (objOrderDetails == null || objOrderDetails.Count == 0)
                {
                    sb.Append("<span class=\"notfound-models\">Order details do not found for this order.</span>");
                }
                else
                {
                    sb.Append(PopulateDetailsTable(objOrderDetails));
                }
            }
        }

        if (objOrderDetails != null)
        {
            objOrderDetails = null;
        }

        return sb.ToString(); ;
    }

    /// <summary>
    /// Populates a HTML table with the order detail data
    /// </summary>
    /// <param name="topModels">Data about the order detail</param>
    /// <returns>HTML table filled with order details</returns>
    private static string PopulateDetailsTable(System.Collections.Generic.List<OrderDetail> objOrderDetails)
    {
        StringBuilder sb = new StringBuilder("<table id='tblDrillDown' class = 'childgridview_style'> \n"
        + "<tr height='40px' class='HeaderRowOnSight'> \n"
        + "<th>ProductName</th> \n"
        + "<th>Unit Price</th> \n"
        + "<th>Quantity</th> \n"
        + "<th>Discount</th> \n"
        + "</tr> \n",
        objOrderDetails.Count * 180);

        foreach (OrderDetail orderDetail in objOrderDetails)
        {
            sb.Append("<tr> \n");

            sb.AppendFormat(CultureInfo.CurrentCulture,
                "<td>{0}</td> ",
                orderDetail.ProductName);

            sb.AppendFormat(CultureInfo.CurrentCulture,
                "<td class=\"cellright\">{0}</td> ",
                orderDetail.UnitPrice);

            sb.AppendFormat(CultureInfo.CurrentCulture,
                "<td class=\"cellright\">{0:n2}</td> ",
                orderDetail.Quantity);

            sb.AppendFormat(CultureInfo.CurrentCulture,
                "<td class=\"cellcenter\">{0}</td> ",
                orderDetail.Discount);

            sb.Append("</tr> \n");
        }

        sb.Append("</table> \n");

        return sb.ToString();
    }

    /// <summary>
    /// Shows a generic error message to the user
    /// </summary>
    private void ShowErrorMessage(string message)
    {
        lblMsgErroTitulo.Text = "ERROR";
        lblMsgErro.Text = "Can not query the database. Error: " + message;

        popupMsgErro.Show();
    }

    /// <summary>
    /// Prepares to show the details for one order.
    /// <para>A new hidden row is inserted below the current row in the grid.</para>
    /// <para>That row will have only one cell, spanned to the entire row.</para>
    /// <para>Inside the new row, a panel is inserted as a simple HTML 'fieldset', just to show a border and some header.</para>
    /// <para>Inside the fieldset, a new panel is inserted. That panel will be filled with details when the user click the button.</para>
    /// </summary>
    /// <param name="gridViewRow">One row from the main grid</param>
    /// <param name="orderRow">One order</param>
    private void BuildNestedPanel(GridViewRow gridViewRow, Order orderRow)
    {
        // Gets the index for the new row
        Table htmlTab = gridOrders.Controls[0] as Table;

        int newRowIndex = htmlTab.Rows.GetRowIndex(gridViewRow) + 1;

        // Creates two panels : external and internal

        // External panel : A simple <fieldset>
        System.Web.UI.WebControls.Panel externalPanel = new Panel();
        externalPanel.EnableViewState = false;
        externalPanel.GroupingText = "Order Detail";
        externalPanel.ID = String.Format(CultureInfo.InvariantCulture, "pDrillDownE_{0}", newRowIndex);
        externalPanel.CssClass = "expand-panel";

        // Internal panel : A <div> as a container for the nested grid
        System.Web.UI.WebControls.Panel internalPanel = new Panel();
        internalPanel.EnableViewState = false;
        internalPanel.ID = String.Format(CultureInfo.InvariantCulture, "pDrillDown_{0}", newRowIndex);

        externalPanel.Controls.Add(internalPanel);

        // Inserts the panels in one cell

        TableCell cell = new TableCell();
        //cell.HorizontalAlign = HorizontalAlign.Left;
        cell.BorderStyle = BorderStyle.None;
        cell.Controls.Add(externalPanel);
        cell.ColumnSpan = VisibleColumns;

        // Inserts the cell in a collection of cell (only one cell)

        TableCell[] cells = new TableCell[1];

        cells[0] = cell;

        // Inserts one row under the current row
        GridViewRow newRow = new GridViewRow(
            newRowIndex,
            newRowIndex,
            DataControlRowType.DataRow,
            DataControlRowState.Normal);

        newRow.ID = String.Format(CultureInfo.InvariantCulture, "linM_{0}", newRowIndex);

        newRow.Style.Add(HtmlTextWriterStyle.Display, "none");

        // Inserts the cell in the new row

        newRow.Cells.AddRange(cells);

        // Inserts the new row in the controls collection of the table (grid)

        htmlTab.Controls.AddAt(newRowIndex, newRow);

        string contextKey = String.Format(CultureInfo.InvariantCulture,
            "{0}-{1}",
            orderRow.OrderID, (chkCachedData.Checked ? 1 : 0));

        // Locates the button and prepares the 'onclick' event

        Image btn = gridViewRow.FindControl("imgModel") as Image;
        //CssClass = "shadowed"
        btn.Attributes.Add("onmouseover", "this.classList.add('shadowed')");
        btn.Attributes.Add("onmouseout", "this.classList.remove('shadowed')");
       
        //btn.Attributes.Add("onmouseover", "if(this.src.endsWith('Images/expand.gif')) this.src='Images/expand_mouseover.gif'");
        //btn.Attributes.Add("onmouseout", "if(this.src.endsWith('Images/expand_mouseover.gif')) this.src='Images/expand.gif'");

        btn.Attributes["onClick"] = String.Format(CultureInfo.InvariantCulture,
            "ExpandDetails('{0}', '{1}', '{2}', '{3}');",
            contextKey,
            newRow.ClientID,
            internalPanel.ClientID,
            btn.ClientID);

        // Insert the ID into the buttons list
        if (_buttons == null)
            _buttons = new System.Collections.Generic.LinkedList<string>();

        _buttons.AddLast(btn.ClientID);
    }
    #endregion
    #endregion
}