linq语句快速筛选curve中polyline

   public void XX()
   {
   
       List<Curve> ents = Z.db.SelectEntities<Curve>();
       if (ents == null || ents.Count == 0) return;
       List<Curve> pl = ents.FindAll(x=>x is Polyline).Select(x=>x as Curve).ToList();
       pl.ForEach(x => {
           x.ChangeEntityColor(1);
           x.Highlight();
           });
       Z.ed.WriteMessage($"共有{pl.Count}个pl\n");
    
   }

效果如下：