private void OnSelectedItemChangedInternal(TViewModel oldValue, TViewModel newValue)
{
ISelectable selectable;
bool containsOld = false;
if (ItemsSource.Contains(oldValue))
{
selectable = oldValue as ISelectable;
if (selectable != null)
{
selectable.IsSelected = false;
}
containsOld = true;
}
selectable = newValue as ISelectable;
if (selectable != null)
{
selectable.IsSelected = true;
}
if (containsOld || newValue != null)
{
NavigationMode mode = newValue != null && newValue.Settings.Metadata.Remove(NavigationConstants.IsFirstNavigation) ? NavigationMode.New : NavigationMode.Refresh;
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Tab, mode, containsOld ? oldValue : null, newValue, this));
}
OnSelectedItemChanged(oldValue, newValue);
RaiseSelectedItemChanged(oldValue, newValue);
}
void IHandler <ForegroundNavigationMessage> .Handle(object sender, ForegroundNavigationMessage message)
{
var viewModel = Application.Current?.MainPage?.BindingContext as IViewModel;
if (viewModel != null && viewModel.Settings.State.Contains(IsRootConstant))
{
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Page, NavigationMode.Foreground, null, viewModel, this, message.Context));
}
}
protected virtual void InitializeRootPage(IViewModel viewModel, IDataContext context)
{
var mainPage = (Page)ViewManager.GetOrCreateView(viewModel, true, context);
var navigationPage = mainPage as NavigationPage;
if (WrapToNavigationPage)
{
navigationPage = CreateNavigationPage(mainPage);
}
var isRoot = navigationPage == null || ReferenceEquals(mainPage, navigationPage);
if (navigationPage != null)
{
INavigationService navigationService;
if (!ServiceProvider.TryGet(out navigationService))
{
navigationService = CreateNavigationService();
ServiceProvider.IocContainer.BindToConstant(navigationService);
}
//Activating navigation provider if need
INavigationProvider provider;
ServiceProvider.TryGet(out provider);
navigationService.UpdateRootPage(navigationPage, viewModel);
mainPage = navigationPage;
}
Application.Current.MainPage = mainPage;
EventHandler <Page, CancelEventArgs> handler = OnBackButtonPressed;
XamarinFormsToolkitExtensions.BackButtonPressed -= handler;
var mode = NavigationMode.New;
if (isRoot)
{
XamarinFormsToolkitExtensions.BackButtonPressed += handler;
if (viewModel.Settings.State.Contains(IsRootConstant))
{
mode = NavigationMode.Refresh;
}
else
{
viewModel.Settings.State.AddOrUpdate(IsRootConstant, null);
}
viewModel.Settings.Metadata.AddOrUpdate(ViewModelConstants.CanCloseHandler, CanCloseRootViewModel);
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Page, mode, null, viewModel, this, context));
}
else
{
mainPage.SetNavigationParameter(NavigationProvider.GenerateNavigationParameter(viewModel));
ServiceProvider.Get <INavigationProvider>().Restore(context);
}
}
void IHandler <ForegroundNavigationMessage> .Handle(object sender, ForegroundNavigationMessage message)
{
var viewModel = Window?.RootViewController?.DataContext() as IViewModel;
if (viewModel != null && viewModel.Settings.State.Contains(IsRootConstant))
{
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Page, NavigationMode.Foreground, null, viewModel, this, message.Context));
}
}
private void OnViewModelsChanged(IList newItems, IList oldItems, int oldStartingIndex)
{
if (newItems != null && newItems.Count != 0)
{
for (int index = 0; index < newItems.Count; index++)
{
var viewModel = (TViewModel)newItems[index];
// ReSharper disable once NotResolvedInText
Should.NotBeNull(viewModel, "newItem");
var selectable = viewModel as ISelectable;
if (selectable != null)
{
selectable.PropertyChanged += _propertyChangedWeakEventHandler;
}
viewModel.Settings.Metadata.AddOrUpdate(NavigationConstants.IsFirstNavigation, null);
OnViewModelAdded(viewModel);
RaiseViewModelAdded(viewModel);
}
}
if (oldItems != null && oldItems.Count != 0)
{
for (int index = 0; index < oldItems.Count; index++)
{
var viewModel = (TViewModel)oldItems[index];
if (SelectedItem == null || ReferenceEquals(SelectedItem, viewModel))
{
TryUpdateSelectedValue(oldStartingIndex + index);
}
var selectable = viewModel as ISelectable;
if (selectable != null)
{
selectable.PropertyChanged -= _propertyChangedWeakEventHandler;
if (selectable.IsSelected)
{
selectable.IsSelected = false;
}
}
INavigationContext context = _lastRemoveContext;
_lastRemoveContext = null;
if (context == null || context.ViewModelFrom != viewModel)
{
context = new NavigationContext(NavigationType.Tab, NavigationMode.Remove, viewModel, null, this);
}
viewModel.Settings.Metadata.Remove(NavigationConstants.IsFirstNavigation);
NavigationDispatcher.OnNavigated(context);
OnViewModelRemoved(viewModel);
RaiseViewModelRemoved(viewModel);
if (DisposeViewModelOnRemove)
{
viewModel.Dispose();
}
}
}
}
protected virtual void OnApplicationStart()
{
var openedViewModels = NavigationDispatcher.GetOpenedViewModels(NavigationType.Page);
foreach (var openedViewModel in openedViewModels)
{
Tracer.Warn($"There is an open view model {openedViewModel} after app restart");
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Page, NavigationMode.Remove, openedViewModel.ViewModel, null, this));
}
}
protected virtual void OnNavigated(INavigationContext context)
{
var vmFrom = context.ViewModelFrom;
var vmTo = context.ViewModelTo;
var mode = context.NavigationMode;
//only this mode allows to renavigate.
if (ReferenceEquals(vmFrom, vmTo) && mode != NavigationMode.Refresh && mode != NavigationMode.Undefined)
{
if (vmFrom != null)
{
Tracer.Error("Possible bug in navigation, navigate to the same view model with mode " + mode);
}
return;
}
if (mode != NavigationMode.Remove && mode != NavigationMode.Background && mode != NavigationMode.Foreground)
{
CurrentViewModel = vmTo;
if (vmTo != null)
{
if (!vmTo.Settings.State.Contains(IsNavigatedConstant))
{
vmTo.Settings.State.AddOrUpdate(IsNavigatedConstant, null);
}
if (!vmTo.Settings.Metadata.Contains(ViewModelConstants.CanCloseHandler))
{
vmTo.Settings.Metadata.AddOrUpdate(ViewModelConstants.CanCloseHandler, CanCloseViewModel);
}
vmTo.InvalidateCommands();
}
}
NavigationDispatcher.OnNavigated(context);
if (context.NavigationMode.IsClose())
{
if (vmFrom != null)
{
vmFrom.Settings.State.Remove(IsNavigatedConstant);
vmFrom.Settings.Metadata.Remove(ViewModelConstants.CanCloseHandler);
#if WINDOWS_UWP
lock (_openedViewModels)
_openedViewModels.Remove(vmFrom.GetViewModelId());
#endif
}
}
else if (vmTo != null)
{
#if WINDOWS_UWP
lock (_openedViewModels)
_openedViewModels[vmTo.GetViewModelId()] = vmTo;
#endif
}
}
public virtual bool Restore(IDataContext context, IViewModelPresenter parentPresenter)
{
_initialized = true;
var viewModel = context.GetData(NavigationConstants.ViewModel);
if (viewModel == null)
{
return(false);
}
if (viewModel.Settings.State.Contains(IsRootConstant))
{
viewModel.Settings.Metadata.AddOrUpdate(ViewModelConstants.CanCloseHandler, (model, o) => false);
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Page, NavigationMode.Refresh, null, viewModel, this, context));
return(true);
}
return(false);
}
private Task <bool> TryCloseRootAsync(IViewModel viewModel, IDataContext context)
{
if (viewModel == null || !viewModel.Settings.State.Contains(IsRootConstant) || viewModel.Settings.Metadata.Contains(IsClosed))
{
return(null);
}
var currentView = viewModel.GetCurrentView <object>();
var backButtonAction = XamarinFormsToolkitExtensions.SendBackButtonPressed?.Invoke(currentView);
if (backButtonAction == null)
{
return(null);
}
var navigationContext = new NavigationContext(NavigationType.Page, NavigationMode.Back, viewModel, null, this, context);
var task = NavigationDispatcher.OnNavigatingAsync(navigationContext);
if (task.IsCompleted)
{
if (task.Result)
{
viewModel.Settings.Metadata.AddOrUpdate(IsClosed, null);
_hasRootPage = false;
NavigationDispatcher.OnNavigated(navigationContext);
}
return(task);
}
return(task.TryExecuteSynchronously(t =>
{
if (!t.Result)
{
return false;
}
_hasRootPage = false;
viewModel.Settings.Metadata.AddOrUpdate(IsClosed, null);
backButtonAction();
NavigationDispatcher.OnNavigated(navigationContext);
return true;
}));
}
internal override void OnDisposeInternal(bool disposing)
{
if (disposing)
{
if (ItemsSource.Count != 0)
{
var viewModels = ItemsSource.ToArray();
for (int i = 0; i < viewModels.Length; i++)
{
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Tab, NavigationMode.Remove, viewModels[i], null, this));
}
}
SelectedItemChanged = null;
_selectedItemChangedNonGeneric = null;
ViewModelAdded = null;
ViewModelRemoved = null;
_viewModelAddedNonGeneric = null;
_viewModelRemovedNonGeneric = null;
}
base.OnDisposeInternal(disposing);
}
protected virtual void InitializeRootView(IViewModel viewModel, IDataContext context)
{
Window.RootViewController = (UIViewController)ViewManager.GetOrCreateView(viewModel, null, context);
NavigationDispatcher.OnNavigated(new NavigationContext(NavigationType.Page, NavigationMode.New, null, viewModel, this, context));
}
