• Article

TreeViewItem.OnExpanded Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Raises an Expanded event when the IsExpanded property changes from false to true.

Namespace:  System.Windows.Controls
Assembly:  System.Windows.Controls (in System.Windows.Controls.dll)

Syntax

'Declaration
Protected Overridable Sub OnExpanded ( _
    e As RoutedEventArgs _
)

protected virtual void OnExpanded(
    RoutedEventArgs e
)

Parameters

Remarks

This method updates the visual state of the TreeViewItem when the value of IsExpanded changes and then raises the Expanded event.

Raising an event invokes the event handler through a delegate. The OnExpanded method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors

When overriding OnExpanded in a derived class, make sure to call the base class’s OnExpanded method so that registered delegates receive the event.

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.