ReactiveUI.RoutedViewHost.RoutedViewHost C# (CSharp) Method

        public RoutedViewHost()
        {
#if NETFX_CORE
            this.DefaultStyleKey = typeof(RoutedViewHost);
#endif
            HorizontalContentAlignment = HorizontalAlignment.Stretch;
            VerticalContentAlignment = VerticalAlignment.Stretch;

            if (ModeDetector.InUnitTestRunner()) {
                ViewContractObservable = Observable.Never<string>();
                return;
            }

            var platform = Locator.Current.GetService<IPlatformOperations>();
            Func<string> platformGetter = () => default(string);

            if (platform == null) {
                // NB: This used to be an error but WPF design mode can't read
                // good or do other stuff good.
                this.Log().Error("Couldn't find an IPlatformOperations. This should never happen, your dependency resolver is broken");
            } else {
                platformGetter = () => platform.GetOrientation();
            }

            ViewContractObservable = Observable.FromEventPattern<SizeChangedEventHandler, SizeChangedEventArgs>(x => SizeChanged += x, x => SizeChanged -= x)
                .Select(_ => platformGetter())
                .DistinctUntilChanged()
                .StartWith(platformGetter())
                .Select(x => x != null ? x.ToString() : default(string));

            var vmAndContract = Observable.CombineLatest(
                this.WhenAnyObservable(x => x.Router.CurrentViewModel),
                this.WhenAnyObservable(x => x.ViewContractObservable),
                (vm, contract) => Tuple.Create(vm, contract));

            this.WhenActivated(d => {
                // NB: The DistinctUntilChanged is useful because most views in 
                // WinRT will end up getting here twice - once for configuring
                // the RoutedViewHost's ViewModel, and once on load via SizeChanged
                d(vmAndContract.DistinctUntilChanged().Subscribe(x => {
                    if (x.Item1 == null) {
                        Content = DefaultContent;
                        return;
                    }

                    var viewLocator = ViewLocator ?? ReactiveUI.ViewLocator.Current;
                    var view = viewLocator.ResolveView(x.Item1, x.Item2) ?? viewLocator.ResolveView(x.Item1, null);

                    if (view == null) {
                        throw new Exception(String.Format("Couldn't find view for '{0}'.", x.Item1));
                    }

                    view.ViewModel = x.Item1;
                    Content = view;
                }, ex => RxApp.DefaultExceptionHandler.OnNext(ex)));
            });
        }
    }