/// <summary>
/// Handles the OnNavigatingFrom event which notifies a page/ViewModel that we are
/// moving AWAY from that view.
/// </summary>
/// <param name="rootFrame"></param>
/// <param name="navMode"></param>
/// <param name="cancel"></param>
/// <param name="suspending"></param>
private void HandleOnNavigatingFrom(Frame rootFrame, NavigationMode navMode, ref bool cancel, bool suspending)
{
if (rootFrame.Content != null)
{
IDictionary <string, object> stateDictionary = null;
FrameworkElement fe = rootFrame.Content as FrameworkElement;
if (fe != null)
{
if (fe.DataContext != null)
{
// Attempt to save the object off.
if (StateManager != null)
{
string key = GenerateStateKey(ViewModelKeyPrefix);
StateManager.SaveObject(key, fe.DataContext);
stateDictionary = StateManager.GetDictionary(key, true);
}
// See if the ViewModel participates in navigation-aware services.
INavigationAware navm = fe.DataContext as INavigationAware;
if (navm != null)
{
var e = (suspending)
? new NavigatingFromEventArgs(navMode, cancel, stateDictionary)
: new NavigatingFromEventArgs(stateDictionary);
navm.OnNavigatingFrom(e);
cancel = e.Cancel;
}
}
// See if the VIEW participates in navigation-aware services.
INavigationAware naView = fe as INavigationAware;
if (naView != null)
{
// Save off the VIEW
stateDictionary = null;
if (StateManager != null)
{
string key = GenerateStateKey(PageKeyPrefix);
stateDictionary = StateManager.GetDictionary(key, false);
}
var e = (suspending)
? new NavigatingFromEventArgs(navMode, cancel, stateDictionary)
: new NavigatingFromEventArgs(stateDictionary);
naView.OnNavigatingFrom(e);
cancel = e.Cancel;
}
}
}
}
private void NotifyOnNavigatingFrom()
{
FrameworkElement contentElement = frame.Content as FrameworkElement;
if (contentElement == null)
{
return;
}
INavigationAware navigationAwareContext = contentElement.DataContext as INavigationAware;
if (navigationAwareContext != null)
{
navigationAwareContext.OnNavigatingFrom();
}
}
