private UniRx.IObservable <int> CounterAnimation(IReactiveProperty <int> property, TimeSpan delay = default)
{
return(property
.Skip(1)
.Scan(new { Previous = 0, Current = property.Value },
(accumulator, newVal) => new { Previous = accumulator.Current, Current = newVal })
.Select(pair =>
{
var direction = pair.Current > pair.Previous ? 1 : -1;
return Observable.Interval(delay == default ? TimeSpan.FromMilliseconds(30) : delay)
.Scan(pair.Previous, (accumulator, _) => accumulator + direction)
.TakeWhile(val => val != pair.Current + direction);
})
.Switch()
.StartWith(property.Value));
}
