How to create column chooser in VirtualGrid

Environment

Product Version	Product	Author
2022.2.622	RadVirtualGrid for WinForms	Dinko Krastev

Description

RadVirtualGrid is a control providing a convenient UI to display only the visible part of a large set of data. By definition, not all of that data needs to be visually available. This article aims to show you how to show/hide columns in RadVirtualGrid depending on the user requirements.

Solution

In this example, we will demonstrate how to use RadCheckedListBox to list all columns in the RadVirtualGrid. Then using the checkbox on each item we can show/hide columns in the RadVirtualGrid control.

public partial class RadForm1 : Telerik.WinControls.UI.RadForm
{
    DataTable data;
    List<string> visibleColumns = new List<string>();
    List<string> columnNames = new List<string>();
    public RadForm1()
    {
        InitializeComponent();
        data = GetTable();
        for (int i = 0; i < 10; i++)
        {
            string name = "Column " + i;
            radCheckedListBox1.Items.Add(name);
            this.visibleColumns.Add(name);
            this.columnNames.Add(name);
        }

        foreach (var item in radCheckedListBox1.Items)
        {
            item.CheckState = Telerik.WinControls.Enumerations.ToggleState.On;
        }

        radCheckedListBox1.ItemCheckedChanged += RadCheckedListBox1_ItemCheckedChanged;

        radVirtualGrid1.CellValueNeeded += RadVirtualGrid1_CellValueNeeded;

        radVirtualGrid1.RowCount = data.Rows.Count;
        radVirtualGrid1.ColumnCount = radCheckedListBox1.CheckedItems.Count;
        radVirtualGrid1.AutoSizeColumnsMode = VirtualGridAutoSizeColumnsMode.Fill;
    }

    private void RadVirtualGrid1_CellValueNeeded(object sender, Telerik.WinControls.UI.VirtualGridCellValueNeededEventArgs e)
    {
        if (e.ColumnIndex < 0 || e.ColumnIndex >= radVirtualGrid1.ColumnCount) return;

        if (e.RowIndex == RadVirtualGrid.HeaderRowIndex)
        {
            e.Value = data.Columns[this.visibleColumns[e.ColumnIndex]];
        }

        if (e.RowIndex < 0)
        {
            return;
        }

        var row = data.Rows[e.RowIndex];
        e.Value = row[this.visibleColumns[e.ColumnIndex]];
    }

    private void RadCheckedListBox1_ItemCheckedChanged(object sender, Telerik.WinControls.UI.ListViewItemEventArgs e)
    {
        if (e.Item.CheckState == Telerik.WinControls.Enumerations.ToggleState.Off)
        {
            this.visibleColumns.Remove(e.Item.Text);
            this.radVirtualGrid1.ColumnCount = 0;
            this.radVirtualGrid1.ColumnCount = this.visibleColumns.Count;
        }
        else
        {
            this.visibleColumns.Add(e.Item.Text);
            this.visibleColumns.Sort(new ColumnNamesComparer(this.columnNames));
        }

        radVirtualGrid1.ColumnCount = this.visibleColumns.Count;
    }

    static DataTable GetTable()
    {

        DataTable table = new DataTable();
        for (int i = 0; i < 10; i++)
        {
            table.Columns.Add("Column " + i, typeof(int));
        }

        for (int i = 0; i < 100; i++)
        {

            table.Rows.Add(new object[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
        }

        return table;
    }
}

public class ColumnNamesComparer : IComparer<string>
{
    public List<string> columnOrder;

    public ColumnNamesComparer(List<string> order)
    {
        this.columnOrder = order;
    }

    public int Compare(string x, string y)
    {
        return this.columnOrder.IndexOf(x).CompareTo(this.columnOrder.IndexOf(y));
    }
}

Partial Public Class RadForm1
    Inherits Telerik.WinControls.UI.RadForm

    Private data As DataTable
    Private visibleColumns As List(Of String) = New List(Of String)()
    Private columnNames As List(Of String) = New List(Of String)()

    Public Sub New()
        InitializeComponent()
        data = GetTable()

        For i As Integer = 0 To 10 - 1
            Dim name As String = "Column " & i
            radCheckedListBox1.Items.Add(name)
            Me.visibleColumns.Add(name)
            Me.columnNames.Add(name)
        Next

        For Each item In radCheckedListBox1.Items
            item.CheckState = Telerik.WinControls.Enumerations.ToggleState.[On]
        Next

        AddHandler radCheckedListBox1.ItemCheckedChanged, AddressOf RadCheckedListBox1_ItemCheckedChanged
        AddHandler radVirtualGrid1.CellValueNeeded, AddressOf RadVirtualGrid1_CellValueNeeded
        radVirtualGrid1.RowCount = data.Rows.Count
        radVirtualGrid1.ColumnCount = radCheckedListBox1.CheckedItems.Count
        radVirtualGrid1.AutoSizeColumnsMode = VirtualGridAutoSizeColumnsMode.Fill
    End Sub

    Private Sub RadVirtualGrid1_CellValueNeeded(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.VirtualGridCellValueNeededEventArgs)
        If e.ColumnIndex < 0 OrElse e.ColumnIndex >= radVirtualGrid1.ColumnCount Then Return

        If e.RowIndex = RadVirtualGrid.HeaderRowIndex Then
            e.Value = data.Columns(Me.visibleColumns(e.ColumnIndex))
        End If

        If e.RowIndex < 0 Then
            Return
        End If

        Dim row = data.Rows(e.RowIndex)
        e.Value = row(Me.visibleColumns(e.ColumnIndex))
    End Sub

    Private Sub RadCheckedListBox1_ItemCheckedChanged(ByVal sender As Object, ByVal e As Telerik.WinControls.UI.ListViewItemEventArgs)
        If e.Item.CheckState = Telerik.WinControls.Enumerations.ToggleState.Off Then
            Me.visibleColumns.Remove(e.Item.Text)
            Me.radVirtualGrid1.ColumnCount = 0
            Me.radVirtualGrid1.ColumnCount = Me.visibleColumns.Count
        Else
            Me.visibleColumns.Add(e.Item.Text)
            Me.visibleColumns.Sort(New ColumnNamesComparer(Me.columnNames))
        End If

        radVirtualGrid1.ColumnCount = Me.visibleColumns.Count
    End Sub

    Private Shared Function GetTable() As DataTable
        Dim table As DataTable = New DataTable()

        For i As Integer = 0 To 10 - 1
            table.Columns.Add("Column " & i, GetType(Integer))
        Next

        For i As Integer = 0 To 100 - 1
            table.Rows.Add(New Object() {0, 1, 2, 3, 4, 5, 6, 7, 8, 9})
        Next

        Return table
    End Function
End Class

Public Class ColumnNamesComparer
    Implements IComparer(Of String)

    Public columnOrder As List(Of String)

    Public Sub New(ByVal order As List(Of String))
        Me.columnOrder = order
    End Sub

    Private Function IComparer_Compare(x As String, y As String) As Integer Implements IComparer(Of String).Compare
        Return Me.columnOrder.IndexOf(x).CompareTo(Me.columnOrder.IndexOf(y))
    End Function
End Class