private static void OnGridPreviewDragOver(object sender, DragEventArgs e)
{
if (_dropData == null)
{
return;
}
var adapter = GetSelectorAdapter(sender as Selector);
var data = _dropData.GetData(typeof(Data)) as Data;
bool sameSelectorTypes = _senderAdapter.GetType() == adapter.GetType();
if (sameSelectorTypes)
{
var hoveredControl = e.OriginalSource as DependencyObject;
// update drag visuals
var currentTargetItem = adapter.GetItem(hoveredControl);
if (currentTargetItem != null)
{
showInsertLine(currentTargetItem, e.GetPosition(currentTargetItem).Y < currentTargetItem.ActualHeight / 4);
}
else
{
hideInsertLine();
}
if (adapter.IsValidDropTarget(hoveredControl))
{
e.Effects = (!isCtrlKeyPressed()) ? DragDropEffects.Move : DragDropEffects.Copy;
}
else
{
e.Effects = DragDropEffects.None;
}
}
// scroll if necessary
ScrollViewer sv = VisualHelpers.FindChild <ScrollViewer>(adapter.Selector);
double verticalPos = e.GetPosition(adapter.Selector).Y;
double scrollOffset = getDragScrollOffset(adapter);
if (verticalPos < DRAG_SCROLL_TOLERANCE) // Top of visible list?
{
sv.ScrollToVerticalOffset(sv.VerticalOffset - scrollOffset); //Scroll up.
}
else if (verticalPos > adapter.Selector.ActualHeight - DRAG_SCROLL_TOLERANCE) //Bottom of visible list?
{
sv.ScrollToVerticalOffset(sv.VerticalOffset + scrollOffset); //Scroll down.
}
e.Handled = sameSelectorTypes;
}
