Revit API多选多重过滤

过滤条件可以这样累加，小技巧。

//墙风管过滤器
class WallDuctSelectionFilter : ISelectionFilter
{
    public bool AllowElement(Element e)
    {
        return (e is Wall) || (e is Duct);
    }

    public bool AllowReference(Reference r, XYZ p)
    {
        return true;
    }
}
[Transaction(TransactionMode.Manual)]
[Regeneration(RegenerationOption.Manual)]
public class cmdTest20110907 : IExternalCommand
{
    public Result Execute(ExternalCommandData cmdData, ref string messages, ElementSet elements)
    {
        UIDocument uiDoc = cmdData.Application.ActiveUIDocument;
        Selection sel = uiDoc.Selection;

        Transaction ts = new Transaction(uiDoc.Document, "多类别多选");
        ts.Start();

        List<Wall> listWall = new List<Wall>();
        List<Duct> listDuct = new List<Duct>();

        IList<Reference> listRef = sel.PickObjects(ObjectType.Element, new WallDuctSelectionFilter(), "选择墙和风管");
        foreach (Reference refObj in listRef)
        {
            Element el = uiDoc.Document.GetElement(refObj);
            if (el is Wall)
            {
                listWall.Add(el as Wall);
            }
            else if (el is Duct)
            {
                listDuct.Add(el as Duct);
            }
        }
        TaskDialog.Show("info", "墙：" + listWall.Count + "\n风管：" + listDuct.Count);

        ts.Commit();
        return Result.Succeeded;
    }
}

from:http://revit.5d6d.com/thread-1330-1-1.html