Is there a "Before" Navigated event?

Im using WPF with Navigation Service. I need to catch a situation before the next page is navigated. Is thera any event "before" next page is navigated?

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

code sample

Private Sub Window_Loaded(ByVal sender As System.Object, B开发者_如何学JAVAyVal 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

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Yes! Try the Navigating event. It is raised when a navigation is requested. More information on NavigationServices events is found in the "Remarks" section of http://msdn.microsoft.com/en-us/library/ms615518.aspx.

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In Silverlight, there is an event "OnNavigatedFom" that occurs before navigating to that page.. Hope it might be the same for WPF as well..

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