/// <summary>
/// Overrides the page's OnNavigatedFrom method and calls the Viewmodel's
/// <see cref="MVVMbasics.Viewmodels.BaseViewmodel.OnNavigatedFrom">OnNavigatedFrom</see> method.
/// </summary>
/// <param name="e"></param>
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
InstantiateViewmodel();
if (Viewmodel != null)
{
ViewState viewState;
if (e.NavigationMode == NavigationMode.Back || IsMvvmBasicsBackNavigation())
{
viewState = ViewState.Closed; // switching to the previous page inside the App
}
else
{
viewState = ViewState.Deactivated; // switching to another page inside the App
}
Viewmodel.OnNavigatedFrom(viewState);
}
// Ensure that the page can correctly be disposed
DataContextChanged -= View_DataContextChanged;
Viewmodel = null;
DataContext = null;
Window.Current.VisibilityChanged -= OnWindowVisibilityChanged;
base.OnNavigatedFrom(e);
}
/// <summary>
/// Retrieves a View and navigates to the corresponding window.
/// </summary>
public void NavigateTo <T>(ParameterList parameters) where T : BaseViewmodel
{
if (_mappings.ContainsKey(typeof(T)))
{
// If the currently active Viewmodel is registered in the Application class, call the OnNavigatedFrom
// event on this Viewmodel!
var application = Application.Current as BaseApplication;
if (application != null)
{
BaseViewmodel currentViewmodel = application.CurrentViewmodel;
if (currentViewmodel != null)
{
currentViewmodel.OnNavigatedFrom(ViewState.Deactivated);
}
}
// Now actually instantiate and open the new window
BaseView window = (BaseView)Activator.CreateInstance(_mappings[typeof(T)]);
_windowStack.Add(window);
window.Initialize(parameters);
window.ShowDialog(); // Returns only after the new window has been closed
// After the new window has been closed (either through NavigateBack or through the X button), pass
// parameters to the previous window (since this is the window that will be reactivated)
if (_windowStack.Count > 1)
{
var previousWindow = _windowStack[_windowStack.Count - 2] as BaseView;
if (previousWindow != null)
{
previousWindow.Initialize(_backParameters);
_backParameters = new ParameterList();
}
}
else
{
if (Application.Current != null) // For non-WPF-applications, this is NULL and the App's main window
// can therefore not be retrieved
// (due to this, passing back parameters will not work in those
// Applications)
{
// If no previous window is found on the back stack, the App's main window is our target:
var previousWindow = Application.Current.MainWindow as BaseView;
if (previousWindow != null)
{
previousWindow.Initialize(_backParameters);
_backParameters = new ParameterList();
}
}
}
// Finally remove the closing window from the back stack:
if (_windowStack.Count > 0)
{
_windowStack.RemoveAt(_windowStack.Count - 1);
}
}
}
/// <summary>
/// Whenever the view's DataContext changes, set its Viewmodel and (if implementing the <code>IBindableView</code>
/// interface) Vm properties accordingly.
/// </summary>
/// <param name="sender"></param>
/// <param name="args"></param>
private void View_DataContextChanged(FrameworkElement sender, DataContextChangedEventArgs args)
{
if (DataContext == null)
{
return;
}
// Retrieve the current DataContext value - this is the Viewmodel instance
Viewmodel = (BaseViewmodel)DataContext;
// If not done already, inject a reference to the global dispatcher helper into the Viewmodel
if (Viewmodel.DispatcherHelper == null)
{
Viewmodel.DispatcherHelper = new DispatcherHelper();
}
//TODO: remove deprecated
// If a ServiceLocator has been registered in the BaseApplication, and if the Viewmodel does not yet
// know about it:
// Inject ServiceLocator into Viewmodel (it will automatically be notified about the
// ServiceLocator's availability by the ServiceLocator's setter method).
#pragma warning disable 618
var application = Application.Current as BaseApplication;
if (application != null)
{
if (Viewmodel.ServiceLocator == null && application.ServiceLocator != null)
{
Viewmodel.ServiceLocator = application.ServiceLocator;
}
}
#pragma warning restore 618
// If implementing the IBindableView interface, also store the current viewmodel in the view's Vm property
if (this.GetType().GetTypeInfo().ImplementedInterfaces
.Any(i => i.GetTypeInfo().IsGenericType&& i.GetGenericTypeDefinition() == typeof(IBindableView <>)))
{
var vmProperty = this.GetType().GetRuntimeProperty("Vm");
if (vmProperty != null)
{
vmProperty.SetMethod.Invoke(this, new[] { DataContext });
}
}
}
/// <summary>
/// Navigates to the last page on the back stack.
/// </summary>
public void NavigateBack()
{
if (_backStack.Count > 0)
{
var application = Application.Current as BaseApplication;
if (application != null)
{
Frame frame = application.RootFrame;
if (frame != null)
{
// Since we manage the back stack on our own instead of relying on the built-in back stack and
// navigation, we cannot simply call frame.NavigateBack()
// Instead, retrieve the Viewmodel instance of the View that is about to be reactivated from the
// back stack, store it in the BackNavigationViewmodel property for the page to pick it up, call
// frame.Navigate() and remove the retrieved Viewmodel instance from the back stack.
BaseViewmodel previousViewmodel = _backStack[_backStack.Count - 1];
TypeInfo type = (TypeInfo)Retrieve(previousViewmodel.GetType());
IsBackNavigation = true;
BackNavigationViewmodel = previousViewmodel;
// Keep the system page stack correctly sized
for (int i = 0; i < 2 && frame.BackStack.Count > 0; ++i)
{
// Remove two pages: the one we're leaving, and the one we're going back to (which will be
// added to the stack by frame.Navigate(...))
frame.BackStack.RemoveAt(frame.BackStack.Count - 1);
}
// Now, actually do navigate...
frame.Navigate(type.AsType());
// ...and keep the internal back stack clear
_backStack.RemoveAt(_backStack.Count - 1);
}
}
}
}
public OpenWindowCommand(BaseViewmodel viewModel)
{
ViewModel = viewModel;
LoginModel = LoginModel;
}
/// <summary>
/// Internally used method that tries to find the Viewmodel registered to the View, and instantiates it if
/// necessary.
/// </summary>
private void InstantiateViewmodel()
{
// If Viewmodel is already known by the View, nothing to do here...
if (Viewmodel == null)
{
// If a Viewmodel has been registered to this View, and if it has not been referenced as DataContext,
// then get the Viewmodel type from the MvvmNavigationTarget attribute, instantiate it, pass a
// reference to the ServiceLocator if requested, and set this instance as the View's DataContext
if (DataContext == null && this.GetType().GetCustomAttributes(typeof(MvvmNavigationTargetAttribute), false).Length > 0)
{
Type viewmodelType =
((MvvmNavigationTargetAttribute)this.GetType().GetCustomAttributes(typeof(MvvmNavigationTargetAttribute), false).First())
.GetViewmodel();
object instance = null;
var application = Application.Current as BaseApplication;
if (application != null)
{
//TODO: remove deprecated
// If a ServiceLocator has been registered in the BaseApplication, and if the Viewmodel does not yet
// know about it:
// Inject ServiceLocator into Viewmodel (it will automatically be notified about the
// ServiceLocator's availability by the ServiceLocator's setter method).
if (viewmodelType.GetConstructors().Any(c =>
c.GetParameters().Count() == 1 &&
c.GetParameters()[0].ParameterType == typeof(ServiceLocator)))
{
#pragma warning disable 618
instance = Activator.CreateInstance(viewmodelType, application.ServiceLocator);
#pragma warning restore 618
}
else
{
instance = application.Resolve(viewmodelType);
}
}
if (instance == null && viewmodelType.GetConstructors().Any(c => !c.GetParameters().Any()))
{
instance = Activator.CreateInstance(viewmodelType);
}
if (instance != null)
{
DataContext = instance;
}
}
// If this View's DataContext has been set (either by the user, or by the code snippet above), we assume
// that the DataContext is an instance of the Viewmodel and store it
if (DataContext != null)
{
Viewmodel = (BaseViewmodel)DataContext;
// If not done already, inject a reference to the global dispatcher helper into the Viewmodel
if (Viewmodel.DispatcherHelper == null)
{
Viewmodel.DispatcherHelper = new DispatcherHelper();
}
//TODO: remove deprecated
// If a ServiceLocator has been registered in the BaseApplication, and if the Viewmodel does not yet
// know about it:
// Inject ServiceLocator into Viewmodel (it will automatically be notified about the
// ServiceLocator's availability by the ServiceLocator's setter method).
#pragma warning disable 618
var application = Application.Current as BaseApplication;
if (application != null)
{
if (Viewmodel.ServiceLocator == null && application.ServiceLocator != null)
{
Viewmodel.ServiceLocator = application.ServiceLocator;
}
}
#pragma warning restore 618
}
}
// In a Viewmodel has been registered to this View (either by the code snippet above, or by an earlier
// method), register it as currently active Viewmodel in the Application
if (Viewmodel != null)
{
if (Application.Current != null)
{
if (Application.Current is BaseApplication)
{
(Application.Current as BaseApplication).CurrentViewmodel = Viewmodel;
}
}
}
}
public ExitWindowCommand(BaseViewmodel viewModel)
{
this.ViewModel = viewModel;
}
/// <summary>
/// Internally used method that tries to find the Viewmodel registered to the View, and instantiates it if
/// necessary.
/// </summary>
private void InstantiateViewmodel()
{
// If Viewmodel is already known by the View, nothing to do here...
if (Viewmodel == null)
{
// ...otherwise, if DataContext is not set yet and if we are navigating backwards, set the DataContext
// to the Viewmodel instance that has been kept within the back stack
if (BindingContext == null)
{
if (IsMvvmBasicsBackNavigation())
{
if (NavigatorServiceReference != null)
{
BindingContext = NavigatorServiceReference.BackNavigationViewmodel;
NavigatorServiceReference.BackNavigationViewmodel = null;
}
}
}
// If a Viewmodel has been registered to this View, and if it has not been referenced as DataContext,
// then get the Viewmodel type from the MvvmNavigationTarget attribute, instantiate it, pass a
// reference to the ServiceLocator if requested, and set this instance as the View's DataContext
var attribute = this.GetType().GetTypeInfo().GetCustomAttribute <MvvmNavigationTargetAttribute>(false);
if (BindingContext == null && attribute != null)
{
Type viewmodelType = attribute.GetViewmodel();
object instance = null;
var application = Application.Current as BaseApplication;
if (application != null)
{
//TODO: remove deprecated
// If a ServiceLocator has been registered in the BaseApplication, and if the Viewmodel does not yet
// know about it:
// Inject ServiceLocator into Viewmodel (it will automatically be notified about the
// ServiceLocator's availability by the ServiceLocator's setter method).
if (viewmodelType.GetTypeInfo().DeclaredConstructors.Any(c =>
c.GetParameters().Count() == 1 &&
c.GetParameters()[0].ParameterType == typeof(ServiceLocator)))
{
#pragma warning disable 618
instance = Activator.CreateInstance(viewmodelType, application.ServiceLocator);
#pragma warning restore 618
}
else
{
instance = application.Resolve(viewmodelType);
}
}
if (instance == null && viewmodelType.GetTypeInfo().DeclaredConstructors.Any(c => !c.GetParameters().Any()))
{
instance = Activator.CreateInstance(viewmodelType);
}
if (instance != null)
{
BindingContext = instance;
}
}
// If this View's DataContext has been set (either by the user, or by the code snippet above), we assume
// that the DataContext is an instance of the Viewmodel and store it
if (BindingContext != null)
{
Viewmodel = (BaseViewmodel)BindingContext;
// If not done already, inject a reference to the global dispatcher helper into the Viewmodel
if (Viewmodel.DispatcherHelper == null)
{
Viewmodel.DispatcherHelper = new DispatcherHelper();
}
//TODO: remove deprecated
// If a ServiceLocator has been registered in the BaseApplication, and if the Viewmodel does not yet
// know about it:
// Inject ServiceLocator into Viewmodel (it will automatically be notified about the
// ServiceLocator's availability by the ServiceLocator's setter method).
#pragma warning disable 618
var application = Application.Current as BaseApplication;
if (application != null)
{
if (Viewmodel.ServiceLocator == null && application.ServiceLocator != null)
{
Viewmodel.ServiceLocator = application.ServiceLocator;
}
}
#pragma warning restore 618
}
}
}
public NewConnectionCommand(BaseViewmodel viewModel)
{
this.ViewModel = viewModel;
}
/// <summary>
/// Stores the currently closing View's Viewmodel instance on the back stack, in order to be able to re-assign
/// it whenever this View will be reactivated again.
/// Gets called from within BaseView's OnNavigatingFrom method.
/// </summary>
/// <param name="viewmodel">Viewmodel instance of the View that is currently being closed</param>
internal void AddToBackstack(BaseViewmodel viewmodel)
{
_backStack.Add(viewmodel);
}
