Using DataGridView CheckBox Column as RadioButton (OptionButton)

Level: Beginner

Knowledge Required:

• DataGridView Control
• Data Binding

Description:
In this post we shall see that how we can transform DataGridView control’s CheckBox column into Radio Button (option button).

I have done 2 main things,

1. Created a back-end logic when user clicks on CheckBox Column so only one CheckBox should be checked at a time
2. Change the look of CheckBox column so it looks a Radio Button Column

So to understand the first one, consider a DataGridView control as shown in the above figure. This DataGridView control is actually bind with a DataSet for example,

As you can see there are 2 columns. The IsSelected column is actually a Boolean column which is normally rendered as CheckBox in DataGridView control. What we will be doing is that we first set our DataGridView to Read Only i.e.,

AllowUserToAddRows = False
AllowUserToDeleteRows = False
ReadOnly = True

We are making our DataGridView control Read Only because it is easier to set the CheckBox checked or unchecked programmatically otherwise DataGridView control itself will be interfering and will create problems and complexities for us.

OK now whenever user clicks on CheckBox we will be performing our custom operation. To do this we will use the DataGridView’s CellContentClick event. Here is the code,

Private Sub ShutDownOptionsDataGridView_CellContentClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles ShutDownOptionsDataGridView.CellContentClick
    If e.ColumnIndex = Me.columnIsSelected.Index Then
        Dim drv As DataRowView
        Dim rowShutDownOption As ShutdownOptionDataSet.ShutDownOptionsRow
        ' in this event handler we know that which DataGridView's row is clicked
        ' so we are going to extract out the actual DataTable's row which is
        ' bind with this DataGridView's Row
        drv = CType(Me.ShutDownOptionsDataGridView.Rows(e.RowIndex).DataBoundItem, DataRowView)
        ' get the DataTable's row
        rowShutDownOption = CType(drv.Row, ShutdownOptionDataSet.ShutDownOptionsRow)

        ' get the row which is currently selected
        Dim rowCurrentlySelected() As ShutdownOptionDataSet.ShutDownOptionsRow
        rowCurrentlySelected = Me.ShutdownOptionDataSet.ShutDownOptions.Select("IsSelected=True")
        ' if some row found then make it de-selected
        If rowCurrentlySelected.Length > 0 Then
            rowCurrentlySelected(0).IsSelected = False
        End If
            ' ok now select the row which is clicked
        rowShutDownOption.IsSelected = True
    End If
End Sub

What we do is first get the row in which IsSelected=True and we make that row IsSelected=False. Then we set the row which is clicked as IsSelected=True.

Next thing is to change the look of CheckBox to OptionButton / RadioButton. For this purpose we will be using DataGridView’s CellPainting event. Here is the code,

Private Sub ShutDownOptionsDataGridView_CellPainting(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellPaintingEventArgs) Handles ShutDownOptionsDataGridView.CellPainting
    If e.ColumnIndex = Me.columnIsSelected.Index AndAlso _
        e.RowIndex >= 0 Then
        e.PaintBackground(e.ClipBounds, True)

        Dim rectRadioButton As Rectangle

        rectRadioButton.Width = 14
        rectRadioButton.Height = 14
        rectRadioButton.X = e.CellBounds.X + (e.CellBounds.Width - rectRadioButton.Width) / 2
        rectRadioButton.Y = e.CellBounds.Y + (e.CellBounds.Height - rectRadioButton.Height) / 2

        If IsDBNull(e.Value) OrElse e.Value = False Then
            ControlPaint.DrawRadioButton(e.Graphics, rectRadioButton, ButtonState.Normal)
        Else
            ControlPaint.DrawRadioButton(e.Graphics, rectRadioButton, ButtonState.Checked)
        End If

        e.Paint(e.ClipBounds, DataGridViewPaintParts.Focus)

        e.Handled = True
    End If
End Sub

As you can see we have used the ControlPaint class to draw the RadioButton / OptionButton.

Download:
DGVCheckBoxAsRadioButton.zip