如何在flutter中做yoyo动画？

Question

I know there is repeat() method on AnimationController but it always starts from the start.

Is there a built-in way to do one forward and one reverse animation, and to repeat that?

Thank you

Answer 1

The repeat method supports the reverse optional named argument, so you can write

animationController.repeat(reverse: true);

This is the modern, simple solution.

Answer 2

You can listen to the status of an animation using addStatusListener . And on animation end reverse it.

final AnimationController c;
...
c.addStatusListener((status) {
  if (status == AnimationStatus.completed) {
    c.reverse();
  }
  else if (status == AnimationStatus.dismissed) {
    c.forward();
  }
});