块插入图中时，块随鼠标移动 EntityJig

//继承EntityJig  两个函数重载   
 public class CADJig : EntityJig
    {
      //  houlinbo QQ420021327
       Entity moveEnt; //移动的实体
        Point3d ptTo;   //插入点
        string promp;   //提示
        public CADJig(Entity ent, string strPromp)
            : base(ent)
        {
            moveEnt = ent; //打开的 ent
            promp = strPromp;
        }


        protected override SamplerStatus Sampler(JigPrompts prompts)
        {
            JigPromptPointOptions optJigPoint = new JigPromptPointOptions(promp);
            //optJigPoint.Cursor = CursorType.RubberBand;
            PromptPointResult resJigPoint = prompts.AcquirePoint(optJigPoint);
            Point3d curPt = resJigPoint.Value;

            if (ptTo != curPt)
            {
                ptTo = curPt;
                return SamplerStatus.OK;
            }
            else
            {
                return SamplerStatus.NoChange;
            }
        }


        protected override bool Update()
        {
            try
            {
                ((BlockReference)moveEnt).Position = ptTo;
            }
            catch (System.Exception)
            {
                return false;
            }
            return true;
        }
     } 
代码 
        /// <summary>
        /// 将文件以块的形式添加到图中  随鼠标移动 JIG
        /// </summary>
        /// <returns></returns>
        public static ObjectId AddBlockDwgJig(Database db, Editor ed, String sourceFileName, String newBlockName, Point3d po, double dAngle, string jigPrompt)
        {
           //  houlinbo  QQ420021327
            BlockReference bref = null;
            Transaction trans = db.TransactionManager.StartTransaction();
            using (trans)
            {
                try
                {
                    BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForWrite);
                    BlockTableRecord btr = (BlockTableRecord)trans.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);

                    ObjectId bobj = new ObjectId();
                    if (bt.Has(newBlockName))
                    {
                        bobj = bt[newBlockName];
                    }
                    else
                    {
                        Database databaseFromFile = Getdb(sourceFileName, System.IO.FileShare.Read, true);
                        bobj = db.Insert(newBlockName, databaseFromFile, true);
                    }
                    bref = new BlockReference(po, bobj);
                    bref.Rotation = dAngle;
                    ObjectId blockobj = btr.AppendEntity(bref);
                    BlockTableRecord empBtr = (BlockTableRecord)trans.GetObject(bt[newBlockName], OpenMode.ForWrite);

                    //用以下两句调用随鼠标移动的效果 在事务未知前调用，否则原点会出现一个块
                    CADJig cadJig = new CADJig(bref as Entity, jigPrompt);
                    PromptResult pr = ed.Drag(cadJig);


                    foreach (ObjectId id in empBtr)
                    {
                        Entity ent = (Entity)trans.GetObject(id, OpenMode.ForRead, true);
                        if (ent.GetType() == typeof(AttributeDefinition))
                        {
                            //块属性
                            AttributeReference attRef = new AttributeReference();
                            AttributeDefinition attDef = (AttributeDefinition)ent;
                            attRef.SetPropertiesFrom(attDef);
                            attRef.SetAttributeFromBlock(attDef, bref.BlockTransform);
                            bref.AttributeCollection.AppendAttribute(attRef);
                            trans.AddNewlyCreatedDBObject(attRef, true);
                        }
                    }
                    trans.AddNewlyCreatedDBObject(bref, true);
                    trans.Commit();
                }
                catch (Exception ex)
                {
                    CE.Elec.Common.ShowMgr.SException("出错Insert ARX " + ex.Message);
                }
                finally
                {
                    trans.Dispose();
                }
            }
            return bref.ObjectId;
        }