// Creates or updates the DropAdorner.
private void UpdateDropAdorner(FrameworkElement adornedElement, bool isVertical, bool insertAfter)
{
// Remove the old adorner if adorner is shown on wrong item container.
if (_dropAdorner != null && _dropAdorner.AdornedElement != adornedElement)
{
RemoveDropAdorner();
}
if (adornedElement == null)
{
return;
}
// Create new adorner if necessary.
if (_dropAdorner == null)
{
// We need to get the AdornerLayer of the ItemContainer and not the ItemsControl.
// The ItemsControl could contain a ScrollContentPresenter with its own
// AdornerLayer. If we would use the AdornerLayer of the Window, then the drop
// adorner could render over the scroll bar of the ItemsControl.
_dropAdorner = new DropAdorner(isVertical, insertAfter, adornedElement);
var adornerLayer = AdornerLayer.GetAdornerLayer(adornedElement);
adornerLayer?.Add(_dropAdorner);
}
// Update the position of the adorner.
if (_dropAdorner != null)
{
_dropAdorner.InsertAfter = insertAfter;
_dropAdorner.InvalidateVisual();
}
}
private void RemoveDropAdorner()
{
if (_dropAdorner != null)
{
var adornerLayer = AdornerLayer.GetAdornerLayer(_dropAdorner.AdornedElement);
adornerLayer?.Remove(_dropAdorner);
_dropAdorner = null;
}
}
private void RemoveDropAdorner()
{
if (_dropAdorner != null)
{
var adornerLayer = AdornerLayer.GetAdornerLayer(_dropAdorner.AdornedElement);
adornerLayer?.Remove(_dropAdorner);
_dropAdorner = null;
}
}
// Creates or updates the DropAdorner.
private void UpdateDropAdorner(FrameworkElement adornedElement, bool isVertical, bool insertAfter)
{
// Remove the old adorner if adorner is shown on wrong item container.
if (_dropAdorner != null && _dropAdorner.AdornedElement != adornedElement)
RemoveDropAdorner();
if (adornedElement == null)
return;
// Create new adorner if necessary.
if (_dropAdorner == null)
{
// We need to get the AdornerLayer of the ItemContainer and not the ItemsControl.
// The ItemsControl could contain a ScrollContentPresenter with its own
// AdornerLayer. If we would use the AdornerLayer of the Window, then the drop
// adorner could render over the scroll bar of the ItemsControl.
_dropAdorner = new DropAdorner(isVertical, insertAfter, adornedElement);
var adornerLayer = AdornerLayer.GetAdornerLayer(adornedElement);
adornerLayer?.Add(_dropAdorner);
}
// Update the position of the adorner.
if (_dropAdorner != null)
{
_dropAdorner.InsertAfter = insertAfter;
_dropAdorner.InvalidateVisual();
}
}
