interpolate method

@override Animation interpolate(Animation current, double scroll)

Интерполяция между анимациями

Implementation

@override
Animation interpolate(Animation current, double scroll) {
  final alpha = current as AlphaAnimation;
  final factor = alpha.factor(scroll);

  return AlphaAnimation(
    start: start,
    end: end,
    alpha: this.alpha + (alpha.alpha - this.alpha) * factor,
  );
}