animateTo method

void animateTo(double value, { Duration duration = const Duration(milliseconds: 300), Curves curve = Curves.easeInOut, })

Animates the scroll position smoothly to value in pixels.

If duration is zero, animation will be ignored.

Example

final scrollController = ScrollController();
scrollController.animateTo(100.0);

Implementation

void animateTo(
  double value, {
  Duration duration = const Duration(milliseconds: 300),
  Curves curve = Curves.easeInOut,
}) {
  if (_attachedElement == null) return;

  // jump immediately if duration is zero
  if (duration == Duration.zero) {
    jumpTo(value);
    return;
  }

  // calculate starting offset and change
  final startOffset = offset;
  final change = value - startOffset;

  // setup animation variables
  final startTime = DateTime.now().millisecondsSinceEpoch;
  final totalDurationMs = duration.inMilliseconds;

  void step() {
    if (_attachedElement == null) return;

    // calculate animation progress
    final elapsed = DateTime.now().millisecondsSinceEpoch - startTime;
    final progress = (elapsed / totalDurationMs).clamp(
      0.0,
      1.0,
    );

    // calculate easing progress
    final easedProgress = curve.build(progress);

    // calculate current scroll position
    final current = startOffset + change * easedProgress;

    // update scroll position
    if (direction == ScrollDirection.vertical) {
      _attachedElement!.scrollTop = current;
    } else {
      _attachedElement!.scrollLeft = current;
    }

    // update scroll offset
    _offset = current;

    // notify listeners of scroll position changes
    notifyListeners();

    // continue animation if not done
    if (progress < 1.0) onComponentRendered(step);
  }

  // start animation
  step();
}