private void DragMove(Func <IInputElement, Point> getPosition, bool isCreatingCopy)
{
if (!m_initialMousePositionToAdorner.HasValue)
{
return;
}
if (!m_isDragging)
{
var position = getPosition.Invoke(m_adornerLayer);
if (DragDropHelper.IsMouseMoveDrag(m_initialMousePositionToAdorner.Value, position))
{
m_draggedElementGhost = DragSourceManagerBase.CreateDraggedElementGhost(m_draggedElement, isCreatingCopy);
this.OnDragStart(getPosition);
this.IsDragging = true;
}
}
if (m_isDragging)
{
this.OnDragMove(getPosition);
this.UpdateGhost(getPosition);
}
}
internal DragSourceManagerBase(UIElement draggedElement, AdornerLayer adornerLayer, UIElement container, bool enableAutoScroll, bool showGhost)
{
if (draggedElement == null)
{
throw new ArgumentNullException("draggedElement");
}
if (container == null)
{
throw new ArgumentNullException("container");
}
m_draggedElement = draggedElement;
m_container = container;
m_adornerLayer = (adornerLayer != null) ? adornerLayer : AdornerLayer.GetAdornerLayer(container);
m_showGhost = showGhost;
if (enableAutoScroll)
{
var scrollViewer = DragSourceManagerBase.GetScrollViewer(draggedElement);
if (scrollViewer != null)
{
m_autoScrollManager = new AutoScrollManager(scrollViewer);
}
}
}
private void DragStart(Func <IInputElement, Point> getPosition)
{
var parent = DragSourceManagerBase.GetPopupOrWindow(m_draggedElement);
var draggedElementPosition = getPosition.Invoke(m_draggedElement);
m_isPopup = (parent is Popup);
m_initialMousePositionToAdorner = (m_adornerLayer != null) ? getPosition.Invoke(m_adornerLayer) : default(Point? );
m_initialMousePositionToDraggedElement = draggedElementPosition;
m_mouseToScreenPositionFactor = DragSourceManagerBase.CalculateMouseToScreenPositionFactor(parent);
m_draggedElementMouseOffset = new Vector(draggedElementPosition.X, draggedElementPosition.Y);
if (m_autoScrollManager != null)
{
m_autoScrollManager.Start();
}
this.IsDragStarted = true;
}
private static Vector CalculateMouseToScreenPositionFactor(FrameworkElement element)
{
if (element == null)
{
return(new Vector(1d, 1d));
}
var source = PresentationSource.FromVisual(element);
if (source == null)
{
var parent = DragSourceManagerBase.GetPopupParent(element);
while (parent != null)
{
source = PresentationSource.FromDependencyObject(parent);
if (source != null)
{
break;
}
parent = DragSourceManagerBase.GetPopupParent(parent);
}
}
double x, y;
if (source != null)
{
var deviceUnits = source.CompositionTarget.TransformToDevice;
x = deviceUnits.M11;
y = deviceUnits.M22;
}
else
{
using (var hwnd = new HwndSource(new HwndSourceParameters()))
{
var deviceUnits = hwnd.CompositionTarget.TransformToDevice;
x = deviceUnits.M11;
y = deviceUnits.M22;
}
}
return(new Vector((x == 0d) ? 1d : 1d / x, (y == 0d) ? 1d : 1d / y));
}
