polyline的 StartPoint 不支持写吗？请教

zoomify · 发表于 2016-1-18 10:55:00

....
                  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 · 发表于 2016-1-18 12:14:00

setpointat

雪山飞狐_lzh · 发表于 2016-1-18 15:03:00

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

zoomify · 发表于 2016-1-18 19:45:00

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

zoomify · 发表于 2016-1-18 19:49:00

setpointat 没这个方法

cairunbin · 发表于 2016-1-18 23:24:00

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 · 发表于 2016-1-19 08:18:00

Dim myCurve As Polyline
....
myCurve.SetPointAt(0,New Point2d(0,0))

zoomify · 发表于 2016-1-19 21:46:00

ivde:
谢谢！
测试是这个原因，理解了。

      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

polyline的 StartPoint 不支持写吗？请教

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