animateToScroll method

void animateToScroll(double scrollDelta, double scrollSpeed)

Implementation

void animateToScroll(double scrollDelta, double scrollSpeed) {
  if (scrollDelta > 0 != prevDeltaPositive) {
    prevDeltaPositive = !prevDeltaPositive;
    futurePosition =
        clientController.offset + (scrollDelta * scrollSpeed * 0.5);
  } else {
    futurePosition = futurePosition + (scrollDelta * scrollSpeed * 0.5);
  }

  final Duration duration;
  if (futurePosition > clientController.position.maxScrollExtent) {
    futurePosition = isPlatformBouncingScrollPhysics
        ? min(clientController.position.maxScrollExtent + 150, futurePosition)
        : clientController.position.maxScrollExtent;
    duration = Duration(
      milliseconds: silkyScrollDuration.inMilliseconds ~/ 2,
    );
  } else if (futurePosition < clientController.position.minScrollExtent) {
    futurePosition = isPlatformBouncingScrollPhysics
        ? max(clientController.position.minScrollExtent - 150, futurePosition)
        : clientController.position.minScrollExtent;
    duration = Duration(
      milliseconds: silkyScrollDuration.inMilliseconds ~/ 2,
    );
  } else {
    duration = silkyScrollDuration;
  }
  isOnSilkyScrolling = true;
  final Future<void> animationEnd = _animationEnd = clientController
      .animateTo(futurePosition, duration: duration, curve: animationCurve);
  animationEnd.whenComplete(() {
    if (animationEnd == _animationEnd) {
      isOnSilkyScrolling = false;
      if (clientController.hasClients == false) {
        return;
      }

      double edgePosition = 0;
      if (clientController.offset >
          clientController.position.maxScrollExtent) {
        isRecoilScroll = true;
        edgePosition = clientController.position.maxScrollExtent;
      } else if (clientController.offset <
          clientController.position.minScrollExtent) {
        isRecoilScroll = true;
        edgePosition = clientController.position.minScrollExtent;
      }

      if (isRecoilScroll) {
        notifyListeners();
        clientController
            .animateTo(
              edgePosition,
              duration: Duration(milliseconds: recoilDurationMS),
              curve: Curves.easeInOutSine,
            )
            .whenComplete(() {
              if (isAlive) {
                isRecoilScroll = false;
                notifyListeners();
              }
            });
      }
    }
  });
}