CAD 二次开发 引用外部DWG并放到对应图层上

 [CommandMethod("InsertBlock")]
        //插入外面的块文件
        public void InsertBlock()
        {
            Editor ed = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument.Editor;
            Document doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
            PromptPointResult ppr = ed.GetPoint("选择插入点");
            Point3d pt = ppr.Value;//获取到插入点 
            //utility.WriteToEditor(pt.ToString());

            string blockPath = @"C:\Users\Administrator\Desktop\变压器.dwg";
            using (Database blkDb = new Database(false, true))
            {

                //read drawing 

                blkDb.ReadDwgFile(blockPath, System.IO.FileShare.Read, true, null);

                blkDb.CloseInput(true);

                using (DocumentLock docLock = doc.LockDocument())//多文档要先这样，否则报至命错误 
                {

                    //新建图层id
                    ObjectId layerId = ObjectId.Null;

                    using (Transaction t = doc.TransactionManager.StartTransaction())
                    {
                        string name = "变压器";//aa是不与blockPath文件中的任何块重名的字符串
                        //insert it as a new block 

                        ObjectId idBTR = doc.Database.Insert(name, blkDb, false);
                        
                        //create a ref to the block 

                        BlockTable bt = (BlockTable)t.GetObject(doc.Database.BlockTableId, OpenMode.ForRead);

                        BlockTableRecord btr = (BlockTableRecord)t.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);



                        //新建图层
                        LayerTable lt = (LayerTable)t.GetObject(doc.Database.LayerTableId, OpenMode.ForWrite);
                        if (!lt.Has("图层4")) 
                        { 
                            LayerTableRecord ltr = new LayerTableRecord();
                            ltr.Name = "图层4";
                            layerId = lt.Add(ltr); 
                            t.AddNewlyCreatedDBObject(ltr, true); 
                        } 
                        //t.Commit();

                        btr.LayoutId = layerId;
                        
                        using (BlockReference bref = new BlockReference(pt, idBTR)) //pt是一个Point3D坐标,这里是插入进当前dwg文件中
                        {
                            bref.LayerId = layerId;
                            btr.AppendEntity(bref);
                            t.AddNewlyCreatedDBObject(bref, true);
                        }

                        
                        t.Commit();
                    }
                }

            }
        }