[CommandMethod("boundaryCAD")]
        public void BoundaryCAD()
        {
            PromptPointOptions pPointOptions = new PromptPointOptions("\n 选择一个点");
            PromptPointResult pPointResult = pDocument.Editor.GetPoint(pPointOptions);
            if (pPointResult.Status == PromptStatus.OK)
            {
                Point3d point3d = pPointResult.Value;

                InvokeArx.Command(true, "_Boundary", point3d, "\0");

                PromptSelectionResult pResult=  pDocument.Editor.SelectLast();
                SelectionSet pSelectionSet = pResult.Value;
                using (Transaction tran = pDatabase.TransactionManager.StartTransaction())
                {
                    foreach (ObjectId pObjectId in pSelectionSet.GetObjectIds())
                    {
                        Entity pEntity = tran.GetObject(pObjectId,OpenMode.ForWrite) as Entity;
                        if ((pEntity as Polyline) != null)
                        {
                            Polyline pPolyline = pEntity as Polyline;
                            pDocument.Editor.WriteMessage("\n当前区域面积是:" + pPolyline.Area.ToString());
                        }
                      pEntity.Erase(true);
                    }
                    tran.Commit();
                }
            }
        }