/// <summary>
/// Handle the ItemsSource changing.
/// </summary>
/// <param name="sender">The combo box.</param>
/// <param name="eventArgs">The event arguments.</param>
private static void OnItemsSourceChanged(DependencyObject sender, DependencyPropertyChangedEventArgs eventArgs)
{
PersistentComboBox box = sender as PersistentComboBox;
box.SelectedValue = box.selectedValue;
if (eventArgs.OldValue is INotifyCollectionChanged)
{
(eventArgs.OldValue as INotifyCollectionChanged).CollectionChanged -= (sender as PersistentComboBox).OnItemsChanged;
if (eventArgs.OldValue is IDataBoundList)
{
(eventArgs.OldValue as IDataBoundList).CollectionChanging -= (sender as PersistentComboBox).OnItemsChanging;
}
}
if (eventArgs.NewValue is INotifyCollectionChanged)
{
(eventArgs.NewValue as INotifyCollectionChanged).CollectionChanged += (sender as PersistentComboBox).OnItemsChanged;
if (eventArgs.NewValue is IDataBoundList)
{
(eventArgs.NewValue as IDataBoundList).CollectionChanging -= (sender as PersistentComboBox).OnItemsChanging;
}
}
}
/// <summary>
/// Do any setup before the ItemsSource changes.
/// </summary>
/// <param name="sender">The combo box.</param>
/// <param name="baseValue">The proposed value of ItemsSource.</param>
/// <returns></returns>
private static object BeforeItemsSourceChanged(DependencyObject sender, object baseValue)
{
PersistentComboBox box = sender as PersistentComboBox;
box.selectedValue = box.SelectedValue;
return(baseValue);
}
/// <summary>
/// Handle a change in the selected value.
/// </summary>
/// <param name="sender">The combo box.</param>
/// <param name="eventArgs">The event arguments.</param>
private static void OnSelectedValueChanged(DependencyObject sender, DependencyPropertyChangedEventArgs eventArgs)
{
PersistentComboBox box = sender as PersistentComboBox;
box.RaiseEvent(new RoutedEventArgs(PersistentComboBox.PersistentSelectedValueChangedEvent, box));
if (box.selectedValue == null)
{
box.selectedValue = eventArgs.NewValue;
}
}