Using Checkboxes in Tree Views

Tree views also can display checkboxes, much like those you can use in menu items. You can make checkboxes appear in a tree view by setting the tree view's CheckBoxes property to True. Here's how that works in the TreeViews example on the CD-ROM, when the user clicks the "Show check boxes" button:

Private Sub Button1_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Button1.Click
    TreeView1.CheckBoxes = True
End Sub

Here's how I display which checkboxes have been checked or unchecked in that example, using the TreeNode class's Checked property:

Private Sub TreeView1_AfterCheck(ByVal sender As Object, _
    ByVal e As System.Windows.Forms.TreeViewEventArgs) _
    Handles TreeView1.AfterCheck
    If e.Node.Checked Then
        TextBox1.Text = "You checked: " & e.Node.Text
    Else
        TextBox1.Text = "You unchecked: " & e.Node.Text
    End If
End Sub

You can see the results in Figure 10.12, where I've checked a node, and the program is reporting that fact in the text box.

Figure 10.12: Handling tree view checkmark events.