private static ControlNavigationHandler EnsureNavigationHandler(DependencyObject d)
{
ControlNavigationHandler handler = GetNavigationHandler(d);
if (handler == null)
{
var handlers = MEFedContainer.Instance.Resolver.Container.GetExportedValues <ControlNavigationHandler>();
handler = handlers.FirstOrDefault(x => x.CanSupportControl(d));
if (handler == null)
{
throw new InvalidOperationException(d.GetType().FullName +
" does not support the NavigateTo. Note: you can create your own by implementing a ControlNavigationHandler and exporting it as type ControlNavigationHandler");
}
SetNavigationHandler(d, handler); // store the handler in the control itself
}
return(handler);
}
private static void OnNavigateOnceLoadedPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
string navigateTo = GetNavigateTo(d);
if (GetNavigateOnceLoaded(d) && !String.IsNullOrEmpty(navigateTo))
{
ControlNavigationHandler handler = GetNavigationHandler(d);
if (handler == null)
{
return;
}
var element = (FrameworkElement)d;
RoutedEventHandler elementOnLoaded = null; // fire this only once
elementOnLoaded = delegate
{
handler.OnEventFired(navigateTo);
element.Loaded -= elementOnLoaded;
};
element.Loaded += elementOnLoaded;
}
}
/// <summary>
/// Sets the NavigationHandler property. This dependency property
/// indicates ....
/// </summary>
public static void SetNavigationHandler(DependencyObject d, ControlNavigationHandler value)
{
d.SetValue(NavigationHandlerProperty, value);
}
