private void AssociateObject_PreviewDragEnter(object sender, DragEventArgs e)
{
if (AssociatedObject.ItemTemplate != null)
{
if (_dragVisual == null)
{
FrameworkElement source = sender as FrameworkElement;
Point dragStart = DragManager.DragStartPosition;
FrameworkElement dragItem = GetItemContainerFromPoint(AssociatedObject, dragStart) as FrameworkElement;
Point itemPos = dragItem.TranslatePoint(new Point(), source);
Point position = e.GetPosition(source);
Point offset = new Point(dragStart.X - itemPos.X, dragStart.Y - itemPos.Y);
Size size = new Size(dragItem.ActualWidth, dragItem.ActualHeight);
IList data = DragDataManager.GetData(e.Data);
_dragVisual = new DragVisual(data, source, AssociatedObject.ItemTemplate, offset, size);
}
e.Handled = true;
}
}
private void AssociatedObject_OnDragInitialize(object sender, DragInitializeEventArgs e)
{
e.Effects = DragDropEffects.All;
IList selectedItems = GetSelectedItemsAsList(AssociatedObject);
if (selectedItems.Count > 0)
{
if (GetItemContainerFromPoint(AssociatedObject, e.DragStartPosition) is FrameworkElement item)
{
Point mousePos = e.GetPosition(AssociatedObject);
Point itemPos = item.TranslatePoint(new Point(), AssociatedObject);
Point offset = new Point(mousePos.X - itemPos.X, mousePos.Y - itemPos.Y);
e.DragVisualSize = new Size(item.ActualWidth, item.ActualHeight);
e.DragVisualOffset = offset;
e.Data = DragDataManager.GenerateDataObject(selectedItems);
}
else
{
AssociatedObject.SelectedItems.Clear();
}
}
}
