private void SetExpanded(bool expand)
{
// Don't do anything if the new state is the same as the previous state
if (IsExpanded == expand)
{
return;
}
if (expand)
{
// Transition the visual state to expanded
VisualStateManager.GoToState(this, ExpanderStatesVisualStateExpandedName, false);
// Find the first focusable element in the expanded content presenter and set focus to it.
if (IsFocusFirstChildOnExpandEnabled && !_expandedContentPresenter.SetFocusOnChildControl(FocusState.Programmatic))
{
// If we're unable to get the first focusable element, it may be because x:DeferLoadStrategy was used, wait for the content
// to load then set focus.
var element = _expandedContentPresenter.Content as FrameworkElement;
if (element != null)
{
element.Loaded += OnContentPresenterContentLoaded;
}
}
}
else
{
VisualStateManager.GoToState(this, ExpanderStatesVisualStateCollapsedName, false);
}
IsExpanded = !IsExpanded;
}