Fires when an element is about to be expanded/collapsed. Allows you to implement a custom element expansion behavior.
The ExpandStateChanging event's data class is ExpandStateChangingEventArgs. The following properties provide information specific to this event:
|Element||Gets the current element that is about to be expanded/collapsed.|
|ElementsToExpandCollapse||Gets the list of elements to be additionally expanded/collapsed.|
|NewState||Gets the new expansion state into which the currently processed element (ExpandStateChangingEventArgs.Element) will be set after your ExpandStateChanging event handler is complete.|
To implement custom element expansion logic, set the AccordionControl.ExpandElementMode property to Multiple and handle the ExpandStateChanging event.
The ExpandStateChanging event fires when an element (e.Element) is about to be expanded/collapsed. The element's new state is specified by the event's e.NewState parameter.
To expand/collapse other elements in code, add these elements to the e.ElementsToExpandCollapse list. Each list item identifies an element to be expanded/collapsed and the new expansion state for this element. After your ExpandStateChanging event handler is complete, the AccordionControl traverses through the e.ElementsToExpandCollapse list and expands/collapses corresponding elements.
Initially, the e.ElementsToExpandCollapse list contains a single item, which is the currently processed element (e.Element).