private static bool HasViewModel(object view, Type viewModelType)
{
if (view == null)
{
return(false);
}
var viewModel = ToolkitExtensions.GetDataContext(view) as IViewModel;
if (viewModel == null)
{
return(false);
}
var vmType = viewModel.GetType();
#if WINDOWS_UWP || XAMARIN_FORMS
if (!viewModelType.GetTypeInfo().IsGenericType)
#else
if (!viewModelType.IsGenericType)
#endif
{ return(vmType.Equals(viewModelType)); }
#if WINDOWS_UWP || XAMARIN_FORMS
if (!vmType.GetTypeInfo().IsGenericType)
#else
if (!vmType.IsGenericType)
#endif
{ return(false); }
return(vmType.GetGenericTypeDefinition().Equals(viewModelType.GetGenericTypeDefinition()));
}
public bool CanClose(IDataContext dataContext)
{
Should.NotBeNull(dataContext, nameof(dataContext));
var viewModel = dataContext.GetData(NavigationConstants.ViewModel);
if (viewModel == null)
{
return(false);
}
var content = CurrentContent;
var canClose = content != null && ToolkitExtensions.GetDataContext(content) == viewModel && _frame.CanGoBack;
if (canClose)
{
return(true);
}
var viewModelId = viewModel.GetViewModelId();
var backStack = _frame.BackStack;
for (int index = 0; index < backStack.Count; index++)
{
if (GetViewModelIdFromParameter(backStack[index].Parameter) == viewModelId)
{
return(true);
}
}
return(false);
}
public bool TryClose(IDataContext dataContext)
{
Should.NotBeNull(dataContext, nameof(dataContext));
var viewModel = dataContext.GetData(NavigationConstants.ViewModel);
if (viewModel == null)
{
return(false);
}
var content = CurrentContent;
if (content != null && ToolkitExtensions.GetDataContext(content) == viewModel && _frame.CanGoBack)
{
_lastContext = dataContext;
_frame.GoBack();
return(true);
}
if (!CanClose(dataContext))
{
return(false);
}
if (RaiseNavigatingRemove(dataContext))
{
bool closed = false;
var viewModelId = viewModel.GetViewModelId();
for (int index = 0; index < _frame.BackStack.Count; index++)
{
if (GetViewModelIdFromParameter(_frame.BackStack[index].Parameter) == viewModelId)
{
_frame.BackStack.RemoveAt(index);
--index;
closed = true;
}
}
if (closed)
{
RaiseNavigated(new RemoveNavigationEventArgs(dataContext));
}
return(closed);
}
return(true);
}
protected virtual IViewModel GetViewModelForView([NotNull] NavigationEventArgsBase args,
[CanBeNull] IViewModel navigationViewModel, [NotNull] INavigationContext context, [NotNull] Type vmType)
{
var view = args.Content;
if (navigationViewModel != null)
{
ViewManager.InitializeViewAsync(navigationViewModel, view, context);
return(navigationViewModel);
}
if (HasViewModel(view, vmType))
{
return((IViewModel)ToolkitExtensions.GetDataContext(view));
}
IDataContext viewModelState = null;
#if WINDOWS_UWP
viewModelState = UwpToolkitExtensions.GetViewModelState(view);
if (viewModelState != null)
{
UwpToolkitExtensions.SetViewModelState(view, null);
}
#endif
var vm = ViewModelProvider.RestoreViewModel(viewModelState, new DataContext
{
{ InitializationConstants.ViewModelType, vmType }
}, true);
if (vm != null)
{
ViewManager.InitializeViewAsync(vm, view, context);
if (viewModelState == null && !vm.Settings.Metadata.GetData(NavigationConstants.DoNotDisposeNoStateViewModel))
{
vm.RegisterNavigationOperation(OperationType.PageNavigation, context)
.ContinueWith <IViewModel>((viewModel, result) => viewModel.Dispose());
}
}
return(vm);
}
protected virtual IViewModel GetViewModelForView([NotNull] NavigationEventArgsBase args,
[CanBeNull] IViewModel navigationViewModel, [NotNull] INavigationContext context, [NotNull] Type vmType)
{
var view = args.Content;
if (navigationViewModel != null)
{
ViewManager.InitializeViewAsync(navigationViewModel, view, context);
return(navigationViewModel);
}
if (HasViewModel(view, vmType))
{
return((IViewModel)ToolkitExtensions.GetDataContext(view));
}
IDataContext viewModelState = null;
#if WINDOWS_UWP
viewModelState = UwpToolkitExtensions.GetViewModelState(view);
if (viewModelState != null)
{
UwpToolkitExtensions.SetViewModelState(view, null);
}
#endif
var vm = ViewModelProvider.RestoreViewModel(viewModelState, new DataContext
{
{ InitializationConstants.ViewModelType, vmType }
}, true);
if (vm != null)
{
ViewManager.InitializeViewAsync(vm, view, context);
}
return(vm);
}
protected virtual INavigationContext CreateContextNavigateTo(NavigationEventArgsBase args)
{
IViewModel viewModelFrom = null, viewModelTo = null;
if (args.NavigationMode.IsClose())
{
viewModelFrom = args.Context.GetData(NavigationConstants.ViewModel);
}
else
{
viewModelTo = args.Context.GetData(NavigationConstants.ViewModel);
}
if (viewModelFrom == null)
{
viewModelFrom = CurrentViewModel;
}
if (args.NavigationMode == NavigationMode.Remove)
{
if (viewModelFrom != null)
{
return(new NavigationContext(NavigationType.Page, NavigationMode.Remove, viewModelFrom, null, this, args.Context));
}
Tracer.Error("Possible bug in navigation, navigate with Remove mode without ViewModel");
}
Guid viewModelId;
var vmType = GetViewModelTypeFromParameter(args.Parameter, out viewModelId);
if (viewModelTo == null && vmType != null)
{
viewModelTo = ViewModelProvider.TryGetViewModelById(viewModelId);
}
if (vmType == null)
{
if (args.Content != null)
{
var items = ViewMappingProvider.FindMappingsForView(args.Content.GetType(), false);
if (items.Count == 1)
{
var type = items[0].ViewModelType;
#if WINDOWS_UWP || XAMARIN_FORMS
if (!type.GetTypeInfo().IsGenericTypeDefinition)
#else
if (!type.IsGenericTypeDefinition)
#endif
{ vmType = type; }
}
else if (viewModelTo == null || items.Count > 1)
{
var viewModel = ToolkitExtensions.GetDataContext(args.Content) as IViewModel;
var type = viewModel?.GetType();
if (type != null && items.Any(item => item.ViewModelType == type))
{
viewModelTo = viewModel;
vmType = type;
}
}
}
if (vmType == null)
{
return(new NavigationContext(NavigationType.Page, args.NavigationMode, viewModelFrom, viewModelTo, this, args.Context));
}
}
return(new NavigationContext(NavigationType.Page, args.NavigationMode, viewModelFrom, viewModelTo, this, args.Context)
{
{ ViewModelTypeConstant, vmType }
});
}
