public PhotoListViewModel(IRouter router = null, IPhotosService service = null)
: base(router)
{
Service = service ?? Locator.Current.GetService <IPhotosService>();
var canLoad = Resumed.FirstAsync().Select(r => r?.LoadedPhotos == null);
LoadPhotos = ReactiveCommand.CreateAsyncTask(canLoad, async o => await Service.GetPhotosAsync());
var canLoadData = this.WhenAnyValue(vm => vm.LoadedPhotos)
.Select(p => p != null);
LoadPhotoData = ReactiveCommand.CreateAsyncTask(canLoadData, async o => await LoadPhotoDataImpl());
Share = ReactiveCommand.CreateAsyncTask(async o => await ShareImpl());
ShowPhoto = ReactiveCommand.CreateAsyncTask(async p => await ShowPhotoImpl((int)p));
loadedPhotos = Resumed.Select(state => state?.LoadedPhotos).Merge(LoadPhotos)
.ObserveOn(RxApp.MainThreadScheduler)
.ToProperty(this, vm => vm.LoadedPhotos, new Photo[0]);
loadedPhotoBytes = LoadPhotoData
.ObserveOn(RxApp.MainThreadScheduler)
.ToProperty(this, vm => vm.LoadedPhotoData);
isLoading = LoadPhotos.IsExecuting.CombineLatest(LoadPhotoData.IsExecuting, (l, ld) => l || ld)
.DistinctUntilChanged()
.ObserveOn(RxApp.MainThreadScheduler)
.ToProperty(this, vm => vm.IsLoading);
this.WhenAnyValue(vm => vm.LoadedPhotos)
.InvokeCommand(this, vm => vm.LoadPhotoData);
}