VB.net Mouse click single cell of gridview, change backcolor and output cell position (col and row) to textbox

I have a gridview in a webform and I would like to know how I can select a single cell anywhere in that gridview using a mouse click.

The selected cell's background colour then changes to a specific colour and a textbox on the form displays the row number and column number which I will pass as parameters to a stored procedure.

When a subsequent cell is selected the last selected cell reverts back to it's original colour and the new cell's background colour is changed and the textbox updates to the new cell's row number and column number.

The closest I've got so far is selecting a whole row, but even this only affects the first cell of the row background-wise. The underline affects all cells in the row.

Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)
    For Each row As GridViewRow In gvProgressGrid.Rows
        If row.RowType = DataControlRowType.DataRow Then
            row.Attributes("onclick") = "this.style.cursor='pointer';this.style.ine';this.style.backgroundColor ='#EEE'"
        End If
    Next

    MyBase.Render(writer)
End Sub

Solution

Basically: in the code behind you set an onclick script for each cell, passing the coordinates of the cell and the textbox for the results.

In the aspx the js script writes the coordinates of the clicked cell in the textbox, iterates all the cells in the table setting the color to white and finally sets the backgrond color to red only for the clicked cell

aspx code:

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="TestEvidenziazione.aspx.vb" Inherits="Web_Test_2010.TestEvidenziazione" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">
        function highlight(my_row, cell, textbox) {
            document.getElementById("<%=txtCellSelected.ClientID%>").value = my_row + ',' + cell;
            var table = document.getElementById("<%=GridView1.ClientID%>");
            for (var i = 0, row; row = table.rows[i]; i++) {
                //iterate through rows
                //rows would be accessed using the "row" variable assigned in the for loop
                for (var j = 0, col; col = row.cells[j]; j++) {
                    //iterate through columns
                    //columns would be accessed using the "col" variable assigned in the for loop
                        col.style.backgroundColor = '#ffffff';
                    if (i == my_row && j == cell) {
                        col.style.backgroundColor = '#ff0000';
                    }
                }
            }
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">

    <div>
        <asp:TextBox ID="txtCellSelected" runat="server"></asp:TextBox>
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true" ShowHeader="false">

    </asp:GridView>
    </div>
    </form>
</body>
</html>

vb.net code:

Public Class TestEvidenziazione
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        LoadData()
    End Sub

    Private Sub LoadData()
        Dim list As New ArrayList
        Dim row1 As New myRowClass
        Dim row2 As New myRowClass
        Dim row3 As New myRowClass

        row1.a = "0,0"
        row1.b = "0,1"
        row1.c = "0,2"

        row2.a = "1,0"
        row2.b = "1,1"
        row2.c = "1,2"

        row3.a = "2,0"
        row3.b = "2,1"
        row3.c = "2,2"
        list.Add(row1)
        list.Add(row2)
        list.Add(row3)
        GridView1.DataSource = list
        GridView1.DataBind()

    End Sub

    Private Class myRowClass
        Public Property a As String
        Public Property b As String
        Public Property c As String
    End Class

    Private Sub GridView1_PreRender(sender As Object, e As System.EventArgs) Handles GridView1.PreRender
        For index_row = 0 To GridView1.Rows.Count - 1
            If GridView1.Rows(index_row).RowType = DataControlRowType.DataRow Then
                For index_cell = 0 To GridView1.Rows(index_row).Cells.Count - 1
                    GridView1.Rows(index_row).Cells(index_cell).Attributes("onclick") = "highlight(" & index_row.ToString & "," & index_cell.ToString & ", " & txtCellSelected.ClientID & "); "
                Next
            End If
        Next
    End Sub
End Class