polyline的 StartPoint 不支持写吗？请教

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....
                    Using trans As Transaction = db.TransactionManager.StartTransaction()


                        Dim myCurve As Curve
                        myCurve = TryCast(trans.GetObject(resEnt.ObjectId, OpenMode.ForWrite), Curve)

                        myCurve.StartPoint = New Point3d(0, 0, 0)

......


最后一句报错 ：The method or operation is not implemented

ivde

setpointat   

雪山飞狐_lzh

最好多研究下C#的继承、虚函数
StartPoint属性的set在polyline中应该是没有继承，或者直接抛出异常了

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Public Overridable Property StartPoint As Point3d
是这样的，不是readonlly

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ivde 发表于 2016-1-18 12:14
setpointat

setpointat   没这个方法

cairunbin

1、因为你的Curve实际上是Polyline，那么你将类型转换为Polyline时，即可调用setpointat方法；
2、Polyline应该override了StartPoint属性。将其set方法改为抛出The method or operation is not implemented异常。StartPoint属性的get还是没问题的。

ivde

Dim myCurve As Polyline

....

myCurve.SetPointAt(0,New Point2d(0,0))

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ivde:
谢谢！
测试是这个原因，理解了。
        <CommandMethod("ccc")>
        Public Sub ccc()
            Dim myCurve As Curve

            Dim db As Database = HostApplicationServices.WorkingDatabase
            Dim ed As Editor = Application.DocumentManager.MdiActiveDocument.Editor
            Dim optEnt As New PromptEntityOptions(vbLf & "选择曲线:")
            Dim resEnt As PromptEntityResult = ed.GetEntity(optEnt)
            If (resEnt.Status = PromptStatus.OK) Then
                Using trans As Transaction = db.TransactionManager.StartTransaction()
                    Dim bt As BlockTable = CType(trans.GetObject(db.BlockTableId, OpenMode.ForRead), BlockTable)

                    Dim btr As BlockTableRecord = CType(trans.GetObject(bt(BlockTableRecord.ModelSpace), OpenMode.ForWrite), BlockTableRecord)

                    myCurve = TryCast(trans.GetObject(resEnt.ObjectId, OpenMode.ForWrite), Curve)

                    If Not myCurve Is Nothing And TypeOf myCurve Is Polyline Then


                        CType(myCurve, Polyline).SetPointAt(0, New Point2d(0, 0))

                        trans.Commit()
                    End If


                End Using

            End If

        End Sub