/**
* Updates navigation history whenever the user navigates.
*
* @param WrapperViewModel navObj : Navigation object representing the current navigation
* point.
*
* @return Void
*/
private void AddToHistory(WrapperViewModel navObj)
{
if (NavigationHistory.Count >= MaxHistoryObjects)
{
NavigationHistory.RemoveAt(0);
}
NavigationHistory.Add(navObj);
}
/**
* Links a navigation handler and instance of the service to the corenavigationviewmodel.
* Inheriting classes will now be registerd with a window
*
* @param INavigationProvider navigationHandler
* @param WrapperViewModel defaultNavigation
* @param forceDefaultNavigation
* @return void
*/
public void Startup(INavigationProvider navigationHandler, WrapperViewModel defaultNavigation = null,
bool forceDefaultNavigation = false)
{
service.RegisterProvider(navigationHandler);
Handler = navigationHandler;
if (defaultNavigation != null)
{
service.SetDefaultNavigation(defaultNavigation, forceDefaultNavigation);
}
}
/**
* Sets default navigation based on parameters. Can force setting if the provider
* is empty.
*
* @param WrapperViewModel navigationObject : The navigation object to be set as default
* @param bool forceIfProviderEmpty : A bool value indicating if the default navigation
* should be forced. False by default.
* @return Void
*/
public void SetDefaultNavigation(WrapperViewModel navigationObject, bool forceIfProviderEmpty = false)
{
DefaultNavigation = navigationObject;
if (forceIfProviderEmpty)
{
if (Provider != null)
{
Provider.Current = navigationObject;
}
}
}
/**
* Navigates to a view specified by the parameter
*
* @param WrapperViewModel navObject : An object representing the view to be navigated to
*
* @return Void
*/
public void Navigate(WrapperViewModel navObject)
{
if (Provider == null)
{
throw new NullReferenceException("The navigation service does not have a registered 'INavigationProvider'");
}
var args = new NavigationEventArgs(navObject, Provider.Current);
OnBeforeNavigate(this, args);
if (Provider.Current != null && Provider.Current != navObject)
{
AddToHistory(Provider.Current);
}
Provider.Current = navObject;
OnAfterNavigate(this, args);
}
/**
* Navigates to the specified navigation object
*
* @param WrapperViewModel navigationObject : Navigation object representing
* the place to navigate to.
*
* @return Void
*/
protected virtual void Navigate(WrapperViewModel navigationObject)
{
service.Navigate(navigationObject);
}
/// <summary>
/// Constructor with ViewModels that indicate where navigation will go and where it came from
/// </summary>
public NavigationEventArgs(WrapperViewModel navigatingTo, WrapperViewModel navigatingFrom = null)
{
ViewModelTo = navigatingTo;
ViewModelFrom = navigatingFrom;
}