/// <summary>
/// Initialize the _rootVisual property (if possible and not already done).
/// </summary>
private void InitializeRootVisual()
{
if (null == _rootVisual)
{
// Try to capture the Application's RootVisual
_rootVisual = Application.Current.RootVisual as FrameworkElement;
if (null != _rootVisual)
{
var rootVisual = _rootVisual;
// Use a weak event listener.
if (_rootVisualMouseMoveListener != null)
{
_rootVisualMouseMoveListener.Detach();
}
_rootVisualMouseMoveListener = new WeakEventListener <ContextMenu, object, MouseEventArgs>(this);
_rootVisualMouseMoveListener.OnEventAction = (instance, source, eventArgs) => instance.HandleRootVisualMouseMove(source, eventArgs);
_rootVisualMouseMoveListener.OnDetachAction = (weakEventListener) => rootVisual.MouseMove -= weakEventListener.OnEvent;
rootVisual.MouseMove += _rootVisualMouseMoveListener.OnEvent;
}
}
}
/// <summary>
/// Called when ItemsSource has changed.
/// Handles setting the selected item.
/// </summary>
/// <param name="oldItemsSource">The old items source.</param>
/// <param name="itemsSource">The items source.</param>
/// <remarks>When switching ItemsSource, the selectedIndex will be used (if possible)
/// to select an item in the new collection.</remarks>
private void OnItemsSourceChanged(IEnumerable oldItemsSource, IEnumerable itemsSource)
{
INotifyCollectionChanged oldObservableItemsSource = oldItemsSource as INotifyCollectionChanged;
INotifyCollectionChanged newObservableItemsSource = itemsSource as INotifyCollectionChanged;
if (oldObservableItemsSource != null)
{
// no longer react to changes in this collection.
// Detach the WeakEventListener
if (null != _weakEventListener)
{
_weakEventListener.Detach();
_weakEventListener = null;
}
}
if (itemsSource != null)
{
int index = GetIndexOf(itemsSource, Value);
if (index > -1)
{
// no need to select a different value, however, currentIndex needs to be set.
CurrentIndex = index;
}
else
{
// use the currentindex to set the value
// or use the _currentIndexDuringInitialization
// or set to first item in list
IEnumerable <object> newItemsSource = itemsSource.OfType <object>();
if (_currentIndexDuringInitialization != null && _currentIndexDuringInitialization.Value > -1)
{
if (IsValidCurrentIndex(CurrentIndex))
{
Value = newItemsSource.ElementAt(CurrentIndex);
}
else
{
Value = IsValidCurrentIndex(_currentIndexDuringInitialization.Value) ? newItemsSource.ElementAt(_currentIndexDuringInitialization.Value) : newItemsSource.FirstOrDefault();
}
_currentIndexDuringInitialization = -1;
}
else if (newItemsSource.Contains(_valueDuringInitialization))
{
// set the value from the initialization cache.
Value = _valueDuringInitialization;
_valueDuringInitialization = new object();
}
else
{
// get value at the same index of the new source, of get the first.
// it is possible for the new source to have 0 items
Value = IsValidCurrentIndex(CurrentIndex) ? newItemsSource.ElementAtOrDefault(CurrentIndex) : newItemsSource.FirstOrDefault();
}
}
if (newObservableItemsSource != null)
{
// if ItemsSource supplies CollectionChanged events, subscribe to them.
// Use a WeakEventListener so that the backwards reference doesn't keep this object alive
_weakEventListener = new WeakEventListener <DomainUpDown, object, NotifyCollectionChangedEventArgs>(this);
_weakEventListener.OnEventAction = (instance, source, eventArgs) => instance.OnItemsChanged(source, eventArgs);
_weakEventListener.OnDetachAction = (weakEventListener) => newObservableItemsSource.CollectionChanged -= weakEventListener.OnEvent;
newObservableItemsSource.CollectionChanged += _weakEventListener.OnEvent;
}
}
else
{
// clear the items collection.
_items.Clear();
}
// determine if the user can spin.
SetValidSpinDirection();
}
