/// <summary>
/// Raises the attached QueryContinueDrag event on a element.
/// </summary>
/// <param name="element">The element to raise the event on.</param>
/// <param name="args">Information about the event.</param>
internal static void OnQueryContinueDrag(this DependencyObject element, SW.QueryContinueDragEventArgs args)
{
if (!args.Handled)
{
IAcceptDrop acceptDrop = element as IAcceptDrop;
if (acceptDrop != null)
{
acceptDrop.OnQueryContinueDrag(args);
}
}
ExtendedRoutedEventHandlerCollection <SW.QueryContinueDragEventHandler, SW.QueryContinueDragEventArgs> handlers = element.GetQueryContinueDragHandlers();
if (handlers != null)
{
handlers.Raise(args);
}
}
/// <summary>
/// Raises the QueryContinueDragEvent on the drag source.
/// </summary>
/// <returns>Information about the QueryContinueDrag event.</returns>
private SW.QueryContinueDragEventArgs OnDragSourceQueryContinueDrag()
{
SW.QueryContinueDragEventArgs queryContinueDragEventArgs =
new SW.QueryContinueDragEventArgs()
{
Action = SW.DragAction.Continue,
EscapePressed = _escapePressed,
KeyStates = KeyStates,
OriginalSource = _dragSource
};
DependencyObject dragSource = _dragSource;
if (dragSource != null)
{
queryContinueDragEventArgs =
dragSource.RaiseRoutedEvent(
queryContinueDragEventArgs,
(acc, e) => acc.OnQueryContinueDrag(e));
}
if (!queryContinueDragEventArgs.Handled)
{
if (queryContinueDragEventArgs.EscapePressed)
{
queryContinueDragEventArgs.Action = SW.DragAction.Cancel;
queryContinueDragEventArgs.Handled = true;
}
else if ((queryContinueDragEventArgs.KeyStates & SW.DragDropKeyStates.LeftMouseButton) != SW.DragDropKeyStates.LeftMouseButton)
{
queryContinueDragEventArgs.Action = (_lastGiveFeedbackEventArgs == null || _lastGiveFeedbackEventArgs.Effects != SW.DragDropEffects.None) ? SW.DragAction.Drop : SW.DragAction.Cancel;
queryContinueDragEventArgs.Handled = true;
}
}
_dragSourceQueryContinueDrag.OnNext(
Event.Create(
_dragSource,
queryContinueDragEventArgs));
return(queryContinueDragEventArgs);
}
public IDisposable Subscribe(IObserver <SW.DragDropEffects> observer)
{
if (IsDragging)
{
throw new InvalidOperationException("A drag operation is already in progress.");
}
IsDragging = true;
// Always execute a QueryContinueDrag first.
_dragStarting.Take(1)
.ObserveOnDispatcher()
.Subscribe(
dragEventArgs =>
{
SW.QueryContinueDragEventArgs args = OnDragSourceQueryContinueDrag();
if (!(args.Handled && args.Action == SW.DragAction.Cancel))
{
OnDragSourceGiveFeedback(_lastDragEventArgs);
_dragStarted.OnNext(dragEventArgs);
}
});
IObservable <SW.DragDropKeyStates> keyStatesChanged =
from dragStarted in _dragStarting
where Application.Current != null
from keyState in
Application.Current.RootVisual
.GetKeyStateChangedOnSelfAndSiblingsAlways(KeyStates)
.TakeUntil(_dragCompleted)
select keyState;
keyStatesChanged.Subscribe(keyState => KeyStates = keyState);
IObservable <bool> escapePressedChanged =
from dragStated in _dragStarting
where Application.Current != null
from escapePressed in
Application.Current.RootVisual
.GetEscapePressedChangedOnSelfAndSiblingsAlways()
.TakeUntil(_dragCompleted)
select escapePressed;
escapePressedChanged.Subscribe(pressed => _escapePressed = pressed);
Observable
.Merge(
keyStatesChanged.IgnoreAll(),
escapePressedChanged.IgnoreAll())
.TakeUntil(_dragCompleted)
.ObserveOnDispatcher()
.Subscribe(_ => RaiseDragSourceEvents(_lastDragEventArgs));
IObservable <IEvent <SW.DragEventArgs> > dragOver =
from dragStartedEvent in _dragStarted
let mouseMoveDragOver = GetMouseMoveDragOver()
from dragMouseOverEvent in mouseMoveDragOver.TakeUntil(_dragCompleted)
from pulseDragMouseOverEvent in
Observable.Merge(
Observable.Return(dragMouseOverEvent),
Observable
.Interval(TimeSpan.FromMilliseconds(MouseOverPulseIntervalInMilliseconds))
.ObserveOnDispatcher()
.Select(_ =>
{
UIElement originalSource = dragMouseOverEvent.EventArgs.OriginalSource as UIElement;
if (originalSource != null)
{
Point pointWithinOriginalSource = dragMouseOverEvent.EventArgs.GetPosition((UIElement)dragMouseOverEvent.EventArgs.OriginalSource);
// if point is no longer within original source find the element
// in the tree that contains the point and make it the original source (and sender)
// or the next dragover event.
if (!new Rect(new Point(0, 0), originalSource.GetSize()).Contains(pointWithinOriginalSource))
{
originalSource = GetDragOverOriginalSource(dragMouseOverEvent.EventArgs);
}
}
return(Event.Create(originalSource, new SW.DragEventArgs(dragMouseOverEvent.EventArgs)
{
OriginalSource = originalSource
}));
})
.TakeUntil(
Observable.Merge(
mouseMoveDragOver.IgnoreAll(),
_dragCompleted.IgnoreAll())))
where IsDragging
select pulseDragMouseOverEvent;
dragOver
.ObserveOnDispatcher()
.Subscribe(dragOverEvent => OnDragOver(dragOverEvent.Sender, dragOverEvent.EventArgs));
_dragStarting.OnNext(Event.Create(_dragSource, _dragStartEventArgs));
_dragCompleted
.ObserveOnDispatcher()
.Subscribe(observer);
return(new AnonymousDisposable(() => { Debug.Assert(false, "Should never detach from DragOperation."); }));
}