build method

@override Widget build(BuildContext context, Widget child, AnimationController controller, EffectEntry entry,)

Builds the widgets necessary to implement the effect, based on the provided AnimationController and EffectEntry.

Implementation

@override
Widget build(
  BuildContext context,
  Widget child,
  AnimationController controller,
  EffectEntry entry,
) {
  final bool shouldRotate = rotation != 0;
  final bool shouldTranslate = offset != Offset.zero;
  if (!shouldRotate && !shouldTranslate) return child;

  final Animation<double> animation = buildAnimation(controller, entry);
  final int count = (entry.duration.inSeconds * hz).floor();

  return getOptimizedBuilder<double>(
    animation: animation,
    builder: (_, __) {
      double value = sin(animation.value * count * pi * 2);
      Widget widget = child;
      if (shouldRotate) {
        widget = Transform.rotate(angle: rotation * value, child: widget);
      }
      if (shouldTranslate) {
        widget = Transform.translate(offset: offset * value, child: widget);
      }
      return widget;
    },
  );
}