&引用；无法使用已与其基础RCW分离的COM对象"；与vb.net窗体事件相关的错误

我正在将arcobjects映射事件挂接到vb.net窗体，以侦听映射选择的更改。这一切都很好，但用户在打开表单时偶尔会报告此错误。我看不到任何模式来重现错误，它似乎是随机的

“无法使用与其基础RCW分离的COM对象”

它源于我挂接事件的表单Load（）方法

谁能帮我理解我做错了什么？我正在FormClosing（）事件中取消映射选择事件的挂钩，我认为这是正确的方法

Public Class MyForm

    Private _activeViewEvents As IActiveViewEvents_Event

    Private Sub FormLoad(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        _activeViewEvents = TryCast(pMxDoc.ActiveView.FocusMap, IActiveViewEvents_Event)
        AddHandler _activeViewEvents.SelectionChanged, AddressOf SelectionChanged    
    End Sub

    Private Sub SelectionChanged
        'do something when selection is changed
    End Sub

    Private Sub FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing
        RemoveHandler _activeViewEvents.SelectionChanged, AddressOf SelectionChanged
    End Sub

End Class

---

创建和销毁处理程序的方法是有效的。当表单打开时更改地图文档时，您可能会收到RCW COM异常。由于您正在使用

FocusMap

创建句柄，因此当文档更改时，

FocusMap

也会更改，这意味着您需要为新的映射文档重新创建句柄。

好，所以我想我已经通过使用ActiveViewChanged事件解决了这个问题。我没有在每次表单加载或新文档事件时重新定位事件，而是尝试侦听ActiveViewChanged事件何时被触发，并每次重新定位SelectionChanged事件。事实证明，每次打开新文档时都会多次触发此操作（不确定原因）。无论如何，问题似乎已经过去了。下面是一些示例代码：

Public Class MyForm

Private _activeViewEvents As IActiveViewEvents_Event
Private _docEvents As IDocumentEvents_Event

Private Sub FormLoad(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    AddHandler _docEvents.ActiveViewChanged, AddressOf ActiveViewChanged
End Sub

Private Sub ActiveViewChanged()
    Dim maps = pMxDoc.Maps
    For i = 0 to maps.Count - 1 'remove handlers from all maps
        RemoveActiveViewEvents(maps.Item(i))
    Next
    SetupActiveViewEvent(pMxDoc.ActiveView.FocusMap) 'only add handler to active map
End Sub

Private Sub RemoveActiveViewEvents(map As IMap)
    _activeViewEvents = CType(map, IActiveViewEvents_Event)
    RemoveHandler _activeViewEvents.SelectionChanged, AddressOf SelectionChanged
End Sub

Private Sub SetupActiveViewEvents(map As IMap)
    _activeViewEvents = CType(map, IActiveViewEvents_Event)
    AddHandler _activeViewEvents.SelectionChanged, AddressOf SelectionChanged
End Sub

Private Sub SelectionChanged
    'do something when selection is changed
End Sub

End Class

---

我已经采取了这种方法，但不幸的是，问题依然存在。我的表单还与文档事件挂钩，因此在文档更改时，它永远不会保持打开状态。每当映射文档发生更改时，用户必须重新加载表单，因此FormLoad（）总是为新文档重新创建处理程序。我怀疑它与更改地图文档有关，因此我将深入研究它。是否有可能您正在使用

封送

或

ComReleaser

处理资源？不，我只处理搜索游标，但与此表单或事件无关。现在通过收听ActiveViewChanged事件修复。解决方案张贴。