animation method

@override List<AnimationController> animation()

Method to init the animation controllers

Implementation

@override
List<AnimationController> animation() {
  var controllers = <AnimationController>[];
  AnimationController alphaController = AnimationController(
      duration: const Duration(milliseconds: 1000), vsync: state);
  Animation<int> alpha =
      IntTween(begin: 255, end: 0).animate(alphaController);
  alpha.addListener(() {
    mAlpha = alpha.value;
    postInvalidate();
  });
  // alpha.
  controllers.add(alphaController);

  AnimationController sizeController = AnimationController(
      duration: const Duration(milliseconds: 1000), vsync: state);
  sizeController.addListener(() {
    mScale = sizeController.value;
  });
  // alpha.
  controllers.add(sizeController);

  return controllers;
}