scrollByPixels method
Scroll by an exact pixels delta (positive = forward / toward end,
negative = backward / toward start).
Implementation
@override
Future<bool> scrollByPixels(double pixels) async {
if (!scrollPosition.hasContentDimensions) return false;
final target = (scrollPosition.pixels + pixels)
.clamp(scrollPosition.minScrollExtent, scrollPosition.maxScrollExtent);
if ((target - scrollPosition.pixels).abs() < 1) return false;
await scrollPosition.animateTo(target, duration: duration, curve: curve);
await _awaitFrameSettle();
return true;
}