Formatting System Cells

The CellFormatting event is used to add formatting to grid systems cells: header cells, filter cells and new row cells. Depending on the RowIndex, you can distinguish the system cells:

RowIndex	VirtualGridRowElement
-1	VirtualGridHeaderRowElement
-2	VirtualGridNewRowElement
-3	VirtualGridFilterRowElement

For example, the code sample below changes the ForeColor, BackColor and GradientStyle for the ContactTitle header cell, CompanyName new row cell and City filter cell:

• C#
• VB.NET

private void radVirtualGrid_CellFormatting(object sender, VirtualGridCellElementEventArgs e)
{
    if (e.CellElement.RowIndex == -1)  //format header row
    {
        if (e.CellElement.ColumnIndex == 3)
        {
            e.CellElement.DrawFill = true;
            e.CellElement.BackColor = Color.Yellow;
            e.CellElement.GradientStyle = Telerik.WinControls.GradientStyles.Solid;
            e.CellElement.ForeColor = Color.Red;
        }
        else
        {
            e.CellElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.ForeColorProperty, ValueResetFlags.Local);
        }
    }
    else if (e.CellElement.RowIndex == -2)//format new row
    {
        if (e.CellElement.ColumnIndex == 1)
        {
            e.CellElement.DrawFill = true;
            e.CellElement.BackColor = Color.Blue;
            e.CellElement.GradientStyle = Telerik.WinControls.GradientStyles.Solid;
            e.CellElement.ForeColor = Color.Aqua;
        }
        else
        {
            e.CellElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.ForeColorProperty, ValueResetFlags.Local);
        }
    }
    else if (e.CellElement.RowIndex == -3)//format filter row
    {
        if (e.CellElement.ColumnIndex == 5)
        {
            e.CellElement.DrawFill = true;
            e.CellElement.BackColor = Color.Black;
            e.CellElement.GradientStyle = Telerik.WinControls.GradientStyles.Solid;
            e.CellElement.ForeColor = Color.White;
        }
        else
        {
            e.CellElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local);
            e.CellElement.ResetValue(LightVisualElement.ForeColorProperty, ValueResetFlags.Local);
        }
    }
}

Private Sub radVirtualGrid_CellFormatting(sender As Object, e As VirtualGridCellElementEventArgs)
    If e.CellElement.RowIndex = -1 Then
        'format header row
        If e.CellElement.ColumnIndex = 3 Then
            e.CellElement.DrawFill = True
            e.CellElement.BackColor = Color.Yellow
            e.CellElement.GradientStyle = Telerik.WinControls.GradientStyles.Solid
            e.CellElement.ForeColor = Color.Red
        Else
            e.CellElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.ForeColorProperty, ValueResetFlags.Local)
        End If
    ElseIf e.CellElement.RowIndex = -2 Then
        'format new row
        If e.CellElement.ColumnIndex = 1 Then
            e.CellElement.DrawFill = True
            e.CellElement.BackColor = Color.Blue
            e.CellElement.GradientStyle = Telerik.WinControls.GradientStyles.Solid
            e.CellElement.ForeColor = Color.Aqua
        Else
            e.CellElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.ForeColorProperty, ValueResetFlags.Local)
        End If
    ElseIf e.CellElement.RowIndex = -3 Then
        'format filter row
        If e.CellElement.ColumnIndex = 5 Then
            e.CellElement.DrawFill = True
            e.CellElement.BackColor = Color.Black
            e.CellElement.GradientStyle = Telerik.WinControls.GradientStyles.Solid
            e.CellElement.ForeColor = Color.White
        Else
            e.CellElement.ResetValue(LightVisualElement.DrawFillProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.BackColorProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.GradientStyleProperty, ValueResetFlags.Local)
            e.CellElement.ResetValue(LightVisualElement.ForeColorProperty, ValueResetFlags.Local)
        End If
    End If
End Sub

Due to the UI virtualization in RadVirtualGrid, cell elements are created only for currently visible cells and are being reused during operations like scrolling, filtering, sorting and so on. In order to prevent applying the formatting to other columns' cell elements (because of the cell reuse) all customization should be reset for the rest of the cell elements.