Question

I know that there is an easy way to do this – but it has beaten me tonight …

I want to know if two events occur within 300 milliseconds of each other, as in a double click.

Two leftdown mouse clicks in 300 milliseconds – I know this is what the reactive framework was built for – but damn if I can find a good doc that has simple examples for all the extenstion operatores – Throttle, BufferWithCount, BufferWithTime – all of which just werent’ doing it for me….

Answer 1

The TimeInterval method will give you the time between values.

public static IObservable<Unit> DoubleClicks<TSource>(
    this IObservable<TSource> source, TimeSpan doubleClickSpeed, IScheduler scheduler)
{
    return source
        .TimeInterval(scheduler)
        .Skip(1)
        .Where(interval => interval.Interval <= doubleClickSpeed)
        .RemoveTimeInterval();
}

If you want to be sure that triple clicks don’t trigger values, you could just use Repeat on a hot observable (I’ve used a FastSubject here as the clicks will all come on one thread and therefore don’t require the heaviness of the normal Subjects):

public static IObservable<TSource> DoubleClicks<TSource>(
    this IObservable<TSource> source, TimeSpan doubleClickSpeed, IScheduler scheduler)
{
    return source.Multicast<TSource, TSource, TSource>(
        () => new FastSubject<TSource>(), // events won't be multithreaded
        values =>
        {
            return values
                .TimeInterval(scheduler)
                .Skip(1)
                .Where(interval => interval.Interval <= doubleClickSpeed)
                .RemoveTimeInterval()
                .Take(1)
                .Repeat();
        });
}