创建arrowsymbol后，为什么屏幕刷新重叠?大奇迹，有源代码，大家快看！

<P>当我用arrowsymbol标志管线的水流向时，没有问题，但标志出后，我拖动屏幕，则出现重叠显现，原有的还在，新的继续叠加，即重影现象，请问哪位高手可以解决？</P>
<P>谢谢！</P>

<P>不会是显卡的问题吧，呵呵</P>

<P>Public Sub m_pActiveViewEvents_OnAfterDrawAll(ByVal display As esriCore.IScreenDisplay, ByVal phase As esriCore.esriViewDrawPhase)
   On Error GoTo ErrorHandler
  
  Dim pEnumFeat As IEnumFeature
  Dim pFeature As IFeature
  Dim pEnvelope As IEnvelope
  Dim pCancel As ITrackCancel
  Dim lLoop As Long
  
  Dim pDT As IDisplayTransformation
  Dim pScreenDisplay As IScreenDisplay
  Dim realWorldDisplayExtent As Double
  Dim pixelExtent As Long
  Dim sizeOfOnePixel As Double
  Dim deviceRECT As tagRECT
  Dim pEnv As IEnvelope
  
  Dim pAMSymbol As IArrowMarkerSymbol
  Dim pRGBColor As IRgbColor
  Dim pSymbol As IMarkerSymbol</P><P>  Dim pEnumLayer As IEnumLayer
  Dim pLayer As IFeatureLayer
  Dim pID As New UID
  Dim bVisible As Boolean
  Dim aryLayers() As String
  Dim iLayers As Integer
  Dim iCount As Integer
  
  Dim pGeoColl As IGeometryCollection
  Dim pSegColl As ISegmentCollection
  Dim pSegment As ISegment
  Dim lSegment As Long
  Dim lGeometry As Long
  Dim pline As ILine
  Dim dAngle As Double
  Dim dLength As Double
  Dim pfeatclass As IFeatureClass
  Dim pFeatures As IFeatureCursor
  Dim l11ActiveCache As Long
  Dim pGraphicsContainer As IGraphicsContainer
  Dim pTextElement As ISimpleLineDecorationElement
  Dim pElement As IElement
  '试验Element
  Set pGraphicsContainer = m_Map
  Set pTextElement = New SimpleLineDecorationElement
  pTextElement.MarkerSymbol.color.RGB = 8612054
  
  
  If phase = esriViewGeoSelection Then  'And pWorkEdit.IsBeingEdited = True
    l11ActiveCache = display.ActiveCache
    Set pDT = display.DisplayTransformation
    If TypeOf display Is IScreenDisplay Then
      Set pScreenDisplay = display
      Set pCancel = m_View.ScreenDisplay.CancelTracker
    End If
    Set pRGBColor = New RgbColor
    pRGBColor.red = 255
    pRGBColor.blue = 0
    pRGBColor.green = 0</P><P>    Set pAMSymbol = New ArrowMarkerSymbol
    pAMSymbol.Style = esriAMSPlain
    
    Dim dArrowSize As Double
    dArrowSize = 10
    If m_Map.ReferenceScale > 0 Then
      deviceRECT = pDT.DeviceFrame
      pixelExtent = deviceRECT.right - deviceRECT.left
      Set pEnv = pDT.VisibleBounds
      
      realWorldDisplayExtent = pEnv.Width
      sizeOfOnePixel = realWorldDisplayExtent / pixelExtent
      If dArrowSize < (sizeOfOnePixel * 2) Then
        dArrowSize = sizeOfOnePixel * 2
      End If
    End If
    pAMSymbol.Width = 10
    pAMSymbol.Size = dArrowSize
    pAMSymbol.color = pRGBColor
    Set pSymbol = pAMSymbol</P><P>     Set pline = New esriCore.Line
     Dim pTargetLayer As IFeatureLayer
    Set pTargetLayer = m_CurrentLayer
    Set pfeatclass = pTargetLayer.FeatureClass
    Dim pQueryFilter As IQueryFilter
    Set pQueryFilter = New QueryFilter
    pQueryFilter.whereClause = ""
    Set pFeatures = pfeatclass.Search(pQueryFilter, False)
    
      Set pFeature = pFeatures.NextFeature
  Do While Not pFeature Is Nothing
    
      If Not pFeature Is Nothing Then
          display.ActiveCache = esriNoScreenCache
          display.StartDrawing 0, esriNoScreenCache
          display.setsymbol pSymbol
        If pFeature.Shape.GeometryType = esriGeometryPolyline And pTargetLayer.FeatureClass.ShapeType = esriGeometryPolyline Then</P><P>            Set pGeoColl = pFeature.Shape
            
            For lGeometry = 0 To pGeoColl.GeometryCount - 1
              Set pSegColl = pGeoColl.Geometry(lGeometry)
              Set pSegment = pSegColl.Segment(pSegColl.SegmentCount - 1)
              dLength = pSegment.length - ConvertPixelsToRW(7)
              If dLength <= 0 Then
                dLength = pSegment.length
              End If
              If dLength > 0 Then
                pSegment.QueryTangent esriExtendTangentAtTo, dLength, False, 1, pline
                dAngle = AngleFromCoords(pline.FromPoint.X, pline.FromPoint.Y, _
                  pline.ToPoint.X, pline.ToPoint.Y)
                ' Draw the arrow</P><P>                pAMSymbol.Angle = dAngle
                With display</P><P>                 .DrawPoint pline.FromPoint
            
                .ActiveCache = esriNoScreenCache
                End With
              End If
            Next lGeometry
          End If
        End If
        Set pFeature = pFeatures.NextFeature
'        If Not pCancel Is Nothing Then
'          If Not pCancel.Continue Then
'            Set pFeature = Nothing
'          End If
'        End If
      
    Loop
  End If
  display.FinishDrawing
  display.ActiveCache = l11ActiveCache
'  display.RemoveCache l11ActiveCache
''  InvalidateRect; m_disp.hwnd, prect, 0
'  display.Invalidate m_View.Extent, False, 0
 ' m_View.Draw display.hDC, Nothing
'  m_View.PartialRefresh esriViewNone, Nothing, Nothing
''
Finally:</P><P>  Set pAMSymbol = Nothing
  
  Exit Sub
  
ErrorHandler:
  Set pAMSymbol = Nothing
  MsgBox "Error " ; err.Number ; ": " ; err.Description ; vbNewLine _
       ; "In " ; err.Source ; " at DrawSelectedArrows.m_pActiveViewEvents_AfterDraw"
End Sub</P><P>请各位大虾帮我看看！</P>

我想你应该在该事件内先把IGraphicsContainer内的东西清空并刷新一次 用该接口的<a href="mk:@MSITStore:C:\arcgis\arcexe83\ArcObjects%20Developer%20Kit\Help\esriCore.chm::/IGraphicsContainer_DeleteAllElements.htm" target="_blank" ><b>DeleteAllElements</b></A>方法