onIntersection method

@override Stream<IntersectionObserverEntry> onIntersection(Element element)

A stream which fires when element intersects with the scroll viewport.

NOTE: This requires IntersectionObserver. Check supportsIntersectionObserver from feature_detector.dart before using.

Implementation

@override
Stream<IntersectionObserverEntry> onIntersection(Element element) {
  assert(feature_detector.supportsIntersectionObserver);
  _intersectionStreams[element] ??=
      StreamController<IntersectionObserverEntry>.broadcast(
          onListen: () => _intersectionObserver!.observe(element),
          onCancel: () => _intersectionObserver!.unobserve(element),
          sync: true);
  return _intersectionStreams[element]!.stream;
}