TreeView.BeforeSelect Event

Definition

Namespace:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

Occurs before the tree node is selected.

public:
 event System::Windows::Forms::TreeViewCancelEventHandler ^ BeforeSelect;

public event System.Windows.Forms.TreeViewCancelEventHandler BeforeSelect;

member this.BeforeSelect : System.Windows.Forms.TreeViewCancelEventHandler 

Public Custom Event BeforeSelect As TreeViewCancelEventHandler 

Event Type

TreeViewCancelEventHandler

Examples

The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the BeforeSelect event. This report helps you learn when the event occurs and can assist you in debugging. To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.

To run the example code, paste it into a project that contains an instance of type TreeView named TreeView1. Then ensure that the event handler is associated with the BeforeSelect event.

private void TreeView1_BeforeSelect(Object sender, TreeViewCancelEventArgs e) {

System.Text.StringBuilder messageBoxCS = new System.Text.StringBuilder();
messageBoxCS.AppendFormat("{0} = {1}", "Node", e.Node );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Action", e.Action );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Cancel", e.Cancel );
messageBoxCS.AppendLine();
MessageBox.Show(messageBoxCS.ToString(), "BeforeSelect Event" );
}

Private Sub TreeView1_BeforeSelect(sender as Object, e as TreeViewCancelEventArgs) _ 
     Handles TreeView1.BeforeSelect

    Dim messageBoxVB as New System.Text.StringBuilder()
    messageBoxVB.AppendFormat("{0} = {1}", "Node", e.Node)
    messageBoxVB.AppendLine()
    messageBoxVB.AppendFormat("{0} = {1}", "Action", e.Action)
    messageBoxVB.AppendLine()
    messageBoxVB.AppendFormat("{0} = {1}", "Cancel", e.Cancel)
    messageBoxVB.AppendLine()
    MessageBox.Show(messageBoxVB.ToString(),"BeforeSelect Event")

End Sub

Remarks

For more information about how to handle events, see Handling and Raising Events.

See also

• OnBeforeSelect(TreeViewCancelEventArgs)
• AfterSelect
• OnAfterSelect(TreeViewEventArgs)