/// <summary>
/// Returns an observable that returns a SW.DragDropKeyStates value
/// whenever it changes, even if one of the events involved
/// is handled or occurs in a sibling.
/// </summary>
/// <param name="that">The element to listen to.</param>
/// <param name="initialState">The initial state SW.DragDropKeyStates.
/// </param>
/// <returns>An observable that returns a SW.DragDropKeyStates value
/// whenever it changes, even if one of the events involved
/// is handled.</returns>
internal static IObservable <SW.DragDropKeyStates> GetKeyStateChangedOnSelfAndSiblingsAlways(this UIElement that, SW.DragDropKeyStates initialState)
{
IEnumerable <UIElement> popupRoots =
VisualTreeExtensions.GetVisualDescendants(that)
.OfType <Popup>()
.Select(popup => popup.Child)
.Where(popupRoot => popupRoot != null);
return(GetKeyStateChanged(
popupRoots
.Select(popupRoot => popupRoot.GetMouseLeftButtonDownAlways())
.Aggregate(that.GetMouseLeftButtonDownAlways(), (left, right) => left.Merge(right)),
popupRoots
.Select(popupRoot => popupRoot.GetMouseLeftButtonUpAlways())
.Aggregate(that.GetMouseLeftButtonUpAlways(), (left, right) => left.Merge(right)),
popupRoots
.Select(popupRoot => popupRoot.GetKeyUpAlways())
.Aggregate(that.GetKeyUpAlways(), (left, right) => left.Merge(right)),
popupRoots
.Select(popupRoot => popupRoot.GetKeyDownAlways())
.Aggregate(that.GetKeyDownAlways(), (left, right) => left.Merge(right)),
initialState));
}
/// <summary>
/// Returns an observable that returns a SW.DragDropKeyStates value
/// whenever it changes, even if one of the events involved
/// is handled.
/// </summary>
/// <param name="that">The element to listen to.</param>
/// <param name="initialState">The initial state SW.DragDropKeyStates.
/// </param>
/// <returns>An observable that returns a SW.DragDropKeyStates value
/// whenever it changes, even if one of the events involved
/// is handled.</returns>
internal static IObservable <SW.DragDropKeyStates> GetKeyStateChangedAlways(
this UIElement that,
SW.DragDropKeyStates initialState)
{
return
(GetKeyStateChanged(that.GetMouseLeftButtonDownAlways(), that.GetMouseLeftButtonUpAlways(), that.GetKeyDownAlways(), that.GetKeyUpAlways(), initialState));
}