如何在Overlay/PopupRoute中制作英雄小部件动画

class HeroWidget extends StatefulWidget {
  @override
  _HeroWidgetState createState() => _HeroWidgetState();
}

class _HeroWidgetState extends State<HeroWidget>
    with SingleTickerProviderStateMixin {
  AnimationController _controller;
  Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: const Duration(milliseconds: 500),
      vsync: this,
    );
    _animation = CurvedAnimation(
      parent: _controller,
      curve: Curves.easeInOut,
    );
    _controller.forward();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _animation,
      builder: (BuildContext context, Widget child) {
        return Opacity(
          opacity: _animation.value,
          child: Transform.scale(
            scale: _animation.value,
            child: child,
          ),
        );
      },
      child: Container(
        // Hero小部件的内容
      ),
    );
  }
}

OverlayEntry overlayEntry = OverlayEntry(
  builder: (BuildContext context) {
    return HeroWidget();
  },
);

Overlay.of(context).insert(overlayEntry);

overlayEntry.remove();