internal async Task <bool> Navigate(Type viewModelType, object[] arguments, XamlNav.NavigationMode navigationMode, NavigationType navigationType)
{
if (!await this.CanChangePage(viewModelType, navigationMode, navigationType))
{
return(false);
}
FrameworkElement view = null;
IViewModel viewModel = null;
// Create a view
if (navigationMode == XamlNav.NavigationMode.Back || navigationMode == XamlNav.NavigationMode.Forward || navigationMode == XamlNav.NavigationMode.New)
{
view = GetView(viewModelType);
}
// Create a view model
if (navigationMode == XamlNav.NavigationMode.Back || navigationMode == XamlNav.NavigationMode.Forward || navigationMode == XamlNav.NavigationMode.Refresh)
{
viewModel = Factory.Create(viewModelType, arguments).As <IViewModel>(); // Use Factory create here so that the factory extensions are invoked
}
// Bind the IsLoading if implemented
if (view != null)
{
view.SetBinding(Control.IsEnabledProperty, new Binding
{
Path = new PropertyPath(nameof(IViewModel.IsLoading)),
Converter = new BooleanInvertConverter()
});
}
if (navigationMode == XamlNav.NavigationMode.Back || navigationMode == XamlNav.NavigationMode.Forward)
{
// Setup the page transition animations
if (view.Transitions != null && view.Transitions.Count > 0)
{
this.ContentTransitions = view.Transitions;
}
else
{
this.ContentTransitions = this.DefaultChildrenTransitions;
}
// we need to keep our old datacontext to dispose them properly later on
var oldDataContext = this.ContentDataContext;
var oldView = this.Content.As <FrameworkElement>();
// Assign our new content
this.Content = view;
await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => view.DataContext = viewModel);
// Invoke the Navigation stuff in the current datacontext
await AsyncHelper.NullGuard(viewModel.As <INavigable>()?.OnNavigatedTo(new NavigationInfo(navigationMode, navigationType, oldDataContext?.GetType())));
// Remove the reference of the old vm from the old view
oldView.IsNotNull(x => x.DataContext = null);
// Now invoke the navigated from on our old data context
await AsyncHelper.NullGuard(oldDataContext?.As <INavigable>()?.OnNavigatedFrom(new NavigationInfo(navigationMode, navigationType, viewModelType)));
// dispose the old viewmodel
oldDataContext?.TryDispose();
}
else if (navigationMode == XamlNav.NavigationMode.New)
{
// NavigationMode.New means recreate the view but preserve the viewmodel
// we need to keep our current datacontext for later reassigning
var currentDataContext = this.ContentDataContext;
var oldView = this.Content.As <FrameworkElement>();
// cancel this if the oldview and the new view are the same
if (oldView.GetType() == view.GetType())
{
return(false);
}
// Assign our content
this.Content = view;
await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => view.DataContext = currentDataContext);
// Invoke the Navigation stuff in the current datacontext
await AsyncHelper.NullGuard(currentDataContext.As <INavigable>()?.OnNavigatedTo(new NavigationInfo(navigationMode, navigationType, currentDataContext.GetType())));
// Remove the reference of the current viewmodel from the old view
oldView.IsNotNull(x => x.DataContext = null);
}
else if (navigationMode == XamlNav.NavigationMode.Refresh)
{
// we need to keep our old datacontext to dispose them properly later on
var oldDataContext = this.ContentDataContext;
// NavigationMode.Refresh means recreate the view model but preserve the view
viewModel = Factory.Create(viewModelType, arguments).As <IViewModel>();
await this.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => view.DataContext = viewModel);
// Invoke the Navigation stuff in the current datacontext
await AsyncHelper.NullGuard(viewModel.As <INavigable>()?.OnNavigatedTo(new NavigationInfo(navigationMode, navigationType, viewModelType)));
// dispose the old viewmodel
oldDataContext?.TryDispose();
}
// Refresh the stacks
if (navigationMode == XamlNav.NavigationMode.Forward)
{
// we have to check if the current viewmodel is the same as the one the top of the forwardstack
// if that is the case we remove it from the stack
// if that is not the case, then we clear the stack
if (this.ForwardStack.Count > 0)
{
var stackEntry = this.ForwardStack[0];
// Remove the stack if equal
if (viewModelType == stackEntry.ViewModelType &&
((stackEntry.Parameters != null && arguments != null && stackEntry.Parameters.SequenceEqual(arguments)) ||
(stackEntry.Parameters == null && arguments == null)))
{
this.ForwardStack.RemoveAt(0);
}
else
{
this.ForwardStack.Clear();
}
}
}
if (navigationMode == XamlNav.NavigationMode.Back || navigationMode == XamlNav.NavigationMode.Forward)
{
this.BackStack.Add(new PageStackEntry(viewModelType, arguments));
}
// remove entries from stack
if (this.MaxStackSize > 1)
{
if (this.BackStack.Count > this.MaxStackSize + 1)
{
this.BackStack.RemoveAt(0);
}
if (this.ForwardStack.Count > this.MaxStackSize)
{
this.ForwardStack.RemoveAt(this.ForwardStack.Count - 1);
}
}
this.CanGoBack = this.BackStack.Count > 1;
this.CanGoForward = this.ForwardStack.Count > 0;
this.Navigated?.Invoke(this, EventArgs.Empty);
return(true);
}
private async void OpenInfoAction(IViewModel arg) => await this.Navigator.NavigateAsync <ItemInfoViewModel>(arg.As <TypeNameItemViewModel>().ItemId);
