private static void ShiftSelect(this ISelectionService selectionService, ISelectable selectable)
{
var siblings = selectable.GetSiblings();
//See if there are any non sibinglings that need to be
var nonSiblingSelected = selectionService.GetSelected()
.Where(s => !siblings.Contains(s))
.ToArray();
foreach (var toUnselect in nonSiblingSelected)
{
selectionService.Unselect(toUnselect);
}
//Now, only existing siblings should be selected
var selected = selectionService.GetSelected();
//If there are none selected, then select all of the sibings up to this one
if (!selected.Any())
{
foreach (var sibling in siblings)
{
selectionService.Select(sibling);
if (sibling == selectable)
{
break;
}
}
}
else
{
//Do a range selection
selectionService.SelectBetween(siblings, selectable, selected.LastOrDefault());
}
}
