有没有“之前”？导航事件？

Question

我正在使用带有导航服务的 WPF。我需要在导航下一页之前捕获情况。导航下一页“之前”是否有任何事件？

Navigate("MyPage1.xaml")
Navigate("MyPage2.xaml")'now, I need a event which shows me : FromPage("MyPage1.xaml") before navigating to "MyPage2.xaml".

代码示例

Private Sub Window_Loaded(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
    Application.NavigationService = Me.ContentFrame.NavigationService
End Sub

Class Application
    ' Application-level events, such as Startup, Exit, and DispatcherUnhandledException
    ' can be handled in this file.
    Public Shared NavigationService As NavigationService
End Class



Private Sub ContentFrame_Navigated(ByVal sender As Object, ByVal e As System.Windows.Navigation.NavigationEventArgs) Handles ContentFrame.Navigated
    If Application.cLang Is Nothing Then Call InitializeLanguage()
    'The following Welcome page is never visible because e.Uri is always the NEXT page
    If e.Uri IsNot Nothing AndAlso (e.Uri.ToString.Contains("Pages/PageWelcome.xaml")) Then
        Call UpdateLanguageCombobox()
    End If
End Sub



Private Sub ContentFrame_Navigating(ByVal sender As Object, ByVal e As System.Windows.Navigation.NavigatingCancelEventArgs) Handles ContentFrame.Navigating
    Dim Uri As Uri = CType(sender, Frame).Source
    If Application.cLang Is Nothing Then Call InitializeLanguage()
    'The following Welcome page is never visible because e.Uri is always the NEXT page
    If e.Uri IsNot Nothing AndAlso (e.Uri.ToString.Contains("Pages/PageWelcome.xaml")) Then
        'Call UpdateLanguageCombobox()
    End If
End Sub

Answer 1

是的！尝试导航事件。当请求导航时会引发它。有关 NavigationServices 事件的详细信息，请参阅 http://msdn 的“备注”部分.microsoft.com/en-us/library/ms615518.aspx。

Answer 2

在 Silverlight 中，在导航到该页面之前会发生一个事件“OnNavigedFom”。希望对于 WPF 来说也是如此。

protected override void OnNavigatedFrom(NavigationEventArgs e) {
    base.OnNavigatedFrom(e);
}