Question

我将arcobjects地图事件挂钩到vb.net表单以侦听地图选择更改。这一切都很好，但用户在打开表单时偶尔会报告此错误。我无法看到任何模式来重现错误，它似乎是随机的。

＆＃34;已与基础RCW分离的COM对象无法使用＆＃34;

它源自 Load（）方法，我挂钩事件。

有谁能帮我理解我做错了什么？我在FormClosing（）事件中取消了地图选择事件，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

Answer 1

您创建和销毁处理程序的方法是有效的。在表单打开时更改地图文档时，您可以收到RCW COM异常。由于您使用FocusMap创建句柄，因此在更改文档时，FocusMap也是如此，这意味着您需要为新地图文档重新创建处理程序。

Answer 2

好的，我想我已经通过使用ActiveViewChanged事件解决了这个问题。我没有在每个表单加载或新文档事件上重新加入事件，而是尝试在每次触发ActiveViewChanged事件时重新调用SelectionChanged事件。事实证明，每次打开新文档时都会多次触发（不确定原因）。无论如何，问题似乎已经消失。这是一些示例代码：

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

＆＃34;已经与其基础RCW分离的COM对象无法使用＆＃34;与vb.net表单事件相关的错误

2 个答案: