public virtual void StartDrag(DragInfo dragInfo)
{
int itemCount = dragInfo.SourceItems.Cast<object>().Count();
if (itemCount == 1)
{
dragInfo.Data = dragInfo.SourceItems.Cast<object>().First();
}
else if (itemCount > 1)
{
dragInfo.Data = TypeUtilities.CreateDynamicallyTypedList(dragInfo.SourceItems);
}
dragInfo.Effects = (dragInfo.Data != null) ?
DragDropEffects.Copy | DragDropEffects.Move :
DragDropEffects.None;
}
static void DragSource_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
// Ignore the click if the user has clicked on a scrollbar.
if (HitTestScrollBar(sender, e))
{
m_DragInfo = null;
return;
}
m_DragInfo = new DragInfo(sender, e);
// If the sender is a list box that allows multiple selections, ensure that clicking on an
// already selected item does not change the selection, otherwise dragging multiple items
// is made impossible.
ItemsControl itemsControl = sender as ItemsControl;
if (m_DragInfo.VisualSourceItem != null && itemsControl != null && itemsControl.CanSelectMultipleItems())
{
IEnumerable selectedItems = itemsControl.GetSelectedItems();
if (selectedItems.Cast<object>().Contains(m_DragInfo.SourceItem))
{
// TODO: Re-raise the supressed event if the user didn't initiate a drag.
e.Handled = true;
}
}
}