private async Task <TransitionResult> ViewModelOnPageTransitionRequested(object sender,
[NotNull] TransitionRequest transitionRequest)
{
if (transitionRequest == null)
{
throw new ArgumentNullException(nameof(transitionRequest));
}
var tcs = new TaskCompletionSource <TransitionResult>();
await Invoker.InvokeAsync(async() =>
{
try
{
if (!(sender is IStoryboardPageViewModel viewModel))
{
throw new InvalidOperationException("Incorrect request of transition");
}
var result = await GoToPageAsync(
transitionRequest.DestinationPageId,
viewModel.StoryboardId,
transitionRequest.DestinationPageContext)
.ConfigureAwait(true);
tcs.SetResult(result);
}
catch (Exception e)
{
ExceptionOccured?.Invoke(this, e);
tcs.SetResult(TransitionResult.Failed);
}
}).ConfigureAwait(false);
return(await tcs.Task.ConfigureAwait(true));
}
public static Task InvokeAsync(this Func <object, TransitionRequest, Task> handler, object arg, TransitionRequest request)
{
if (handler == null)
{
return(Task.CompletedTask);
}
var invocationList = handler.GetInvocationList();
var handlerTasks = new Task[invocationList.Length];
for (var i = 0; i < invocationList.Length; i++)
{
handlerTasks[i] = ((Func <object, TransitionRequest, Task>)invocationList[i])(arg, request);
}
return(Task.WhenAll(handlerTasks));
}