/// <summary>
/// Creates a new NavigationService from the gived Frame to the
/// WindowWrapper collection. In addition, it optionally will setup the
/// shell back button to react to the nav of the Frame.
/// A developer should call this when creating a new/secondary frame.
/// The shell back button should only be setup one time.
/// </summary>
public INavigationService NavigationServiceSetup(
BackButton backButton,
ExistingContent existingContent,
Frame frame)
{
frame.Language = ApplicationLanguages.Languages[0];
frame.Content = existingContent == ExistingContent.Include ? Window.Current.Content : null;
var navigationService = new NavigationService(frame);
navigationService.FrameFacade.BackButtonHandling = backButton;
WindowWrapper.Current().NavigationServices.Add(navigationService);
if (backButton == BackButton.Attach)
{
// TODO: unattach others
// update shell back when backstack changes
// only the default frame in this case because secondary should not dismiss the app
frame.RegisterPropertyChangedCallback(Frame.BackStackDepthProperty, (s, args) => UpdateShellBackButton());
// update shell back when navigation occurs
// only the default frame in this case because secondary should not dismiss the app
frame.Navigated += (s, args) => UpdateShellBackButton();
}
// this is always okay to check, default or not
// expire any state (based on expiry)
DateTime cacheDate;
// default the cache age to very fresh if not known
var otherwise = DateTime.MinValue.ToString(CultureInfo.InvariantCulture);
if (DateTime.TryParse(navigationService.FrameFacade.GetFrameState(CacheDateKey, otherwise), out cacheDate))
{
var cacheAge = DateTime.Now.Subtract(cacheDate);
if (cacheAge >= CacheMaxDuration)
{
// clear state in every nav service in every view
foreach (var service in WindowWrapper.ActiveWrappers.SelectMany(x => x.NavigationServices))
{
service.FrameFacade.ClearFrameState();
}
}
}
return(navigationService);
}
private void RaiseForwardRequested()
{
var args = new HandledEventArgs();
ForwardRequested?.Invoke(null, args);
if (args.Handled)
{
return;
}
foreach (var frame in WindowWrapper.Current().NavigationServices.Select(x => x.FrameFacade))
{
frame.RaiseForwardRequested(args);
if (args.Handled)
{
return;
}
}
NavigationService.GoForward();
}
/// <summary>
/// Default Hardware/Shell Back handler overrides standard Back behavior
/// that navigates to previous app in the app stack to instead cause a backward page navigation.
/// Views or Viewodels can override this behavior by handling the BackRequested
/// event and setting the Handled property of the BackRequestedEventArgs to true.
/// </summary>
private void RaiseBackRequested(ref bool handled)
{
var args = new HandledEventArgs();
BackRequested?.Invoke(null, args);
if (handled = args.Handled)
{
return;
}
foreach (var frame in WindowWrapper.Current().NavigationServices.Select(x => x.FrameFacade).Reverse())
{
frame.RaiseBackRequested(args);
if (handled = args.Handled)
{
return;
}
}
NavigationService.GoBack();
}