protected void DisplayNavigationEntry(INavigationEntry entry)
{
if (entry == null)
{
// If this entry is null then simply pass null to the deriving class
DisplayPage(null);
}
else
{
// Cast to the internal NavigationEntry class so we can access all members
// TODO : Try to get rid of the need for this cast? (or check that it is of the correct type and provide alternatives for derived classes)
NavigationEntry internalEntry = (NavigationEntry)entry;
// If the page and VM have not been created then do so
if (internalEntry.ViewLifetimeContext == null)
{
CreatePage(internalEntry);
}
// Navigate to the relevant page
DisplayPage(internalEntry.ViewLifetimeContext.View);
}
}
// *** Private Methods ***
private void CreatePage(NavigationEntry entry)
{
// Create the View
IViewLifetimeContext viewLifetimeContext = viewFactory.CreateView(entry.PageName);
entry.ViewLifetimeContext = viewLifetimeContext;
// Activate the view model if it implements IActivatable<,>
// NB: Use reflection as we do not know the generic parameter types
object viewModel = entry.ViewLifetimeContext.ViewModel;
Type activatableInterface = ReflectionHelper.GetClosedGenericType(viewModel, typeof(IActivatable <,>));
if (activatableInterface != null)
{
// If required deserialize the arguments and state
entry.DeserializeData(activatableInterface.GenericTypeArguments[0], activatableInterface.GenericTypeArguments[1]);
// Activate the view model
MethodInfo activateMethod = activatableInterface.GetTypeInfo().GetDeclaredMethod("Activate");
activateMethod.Invoke(viewModel, new object[] { entry.Arguments, entry.State });
}
}
public void NavigateTo(string pageName, object arguments)
{
// Call NavigatingFrom on the existing navigation entry (if one exists)
CallNavigatingFrom(CurrentNavigationEntry, NavigationMode.New);
// Get the old value of CanGoBack
bool oldCanGoBack = CanGoBack;
// Create the new navigation entry and push it onto the navigation stack
NavigationEntry navigationEntry = new NavigationEntry(pageName, arguments);
navigationStack.Push(navigationEntry);
// Navigate to the page
DisplayNavigationEntry(navigationEntry);
// If the value of CanGoBack has changed then raise an event
if (CanGoBack != oldCanGoBack)
{
OnCanGoBackChanged();
}
// Call NavigatedTo on the new navigation entry
CallNavigatedTo(navigationEntry, NavigationMode.New);
}
// *** Private Methods ***
private void SavePageState(NavigationEntry entry)
{
// If the view model is IActivatable<,> then use this to save the page state
// NB: First check that the view has been created - this may still have state from a previous instance
// NB: Use reflection as we do not know the generic parameter types
if (entry.ViewLifetimeContext != null)
{
// Get the generic IActivatable<,> interface
object viewModel = entry.ViewLifetimeContext.ViewModel;
Type activatableInterface = ReflectionHelper.GetClosedGenericType(viewModel, typeof(IActivatable <,>));
if (activatableInterface != null)
{
// Save the state
MethodInfo saveStateMethod = activatableInterface.GetTypeInfo().GetDeclaredMethod("SaveState");
entry.State = saveStateMethod.Invoke(viewModel, null);
// Serialize the arguments and state
entry.SerializeData(activatableInterface.GenericTypeArguments[0], activatableInterface.GenericTypeArguments[1]);
}
}
}
private void SavePageState(NavigationEntry entry)
{
// If the view model is IActivatable<,> then use this to save the page state
// NB: First check that the view has been created - this may still have state from a previous instance
// NB: Use reflection as we do not know the generic parameter types
if (entry.ViewLifetimeContext != null)
{
// Get the generic IActivatable<,> interface
object viewModel = entry.ViewLifetimeContext.ViewModel;
Type activatableInterface = ReflectionHelper.GetClosedGenericType(viewModel, typeof(IActivatable<,>));
if (activatableInterface != null)
{
// Save the state
MethodInfo saveStateMethod = activatableInterface.GetTypeInfo().GetDeclaredMethod("SaveState");
entry.State = saveStateMethod.Invoke(viewModel, null);
// Serialize the arguments and state
entry.SerializeData(activatableInterface.GenericTypeArguments[0], activatableInterface.GenericTypeArguments[1]);
}
}
}
// *** Private Methods ***
private void CreatePage(NavigationEntry entry)
{
// Create the View
IViewLifetimeContext viewLifetimeContext = viewFactory.CreateView(entry.PageName, navigationContext);
entry.ViewLifetimeContext = viewLifetimeContext;
// Activate the view model if it implements IActivatable<,>
// NB: Use reflection as we do not know the generic parameter types
object viewModel = entry.ViewLifetimeContext.ViewModel;
Type activatableInterface = ReflectionHelper.GetClosedGenericType(viewModel, typeof(IActivatable<,>));
if (activatableInterface != null)
{
// If required deserialize the arguments and state
entry.DeserializeData(activatableInterface.GenericTypeArguments[0], activatableInterface.GenericTypeArguments[1]);
// Activate the view model
MethodInfo activateMethod = activatableInterface.GetTypeInfo().GetDeclaredMethod("Activate");
activateMethod.Invoke(viewModel, new object[] { entry.Arguments, entry.State });
}
}
public void NavigateTo(string pageName, object arguments)
{
// Call NavigatingFrom on the existing navigation entry (if one exists)
CallNavigatingFrom(CurrentNavigationEntry, NavigationMode.New);
// Get the old value of CanGoBack
bool oldCanGoBack = CanGoBack;
// Create the new navigation entry and push it onto the navigation stack
NavigationEntry navigationEntry = new NavigationEntry(pageName, arguments);
navigationStack.Push(navigationEntry);
// Navigate to the page
DisplayNavigationEntry(navigationEntry);
// If the value of CanGoBack has changed then raise an event
if (CanGoBack != oldCanGoBack)
OnCanGoBackChanged();
// Call NavigatedTo on the new navigation entry
CallNavigatedTo(navigationEntry, NavigationMode.New);
}
