问如何为AnimatedContainer创建setState函数

EN

class SectionTaps extends StatefulWidget {
  SectionTaps(this.isActive);

  bool isActive = false;

  _SectionTapsState createState() => _SectionTapsState();
}

class _SectionTapsState extends State<SectionTaps> {
  bool _isActive = false;
  double _width = 255.0;
  void _handleTap() {
    setState(() {
        print ('Set State Called.');
      _isActive = widget.isActive;
      _isActive == true ? _width = 55.0 : _width = 255.0;
      //change container width
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Center(
        child: GestureDetector(
          onTap: () {
            _handleTap();
          },
          child: new AnimatedContainer(
            duration: Duration(seconds: 1),
            height: 88.0,
            width: 255.0,
            decoration: new BoxDecoration(
              color: new Color(0xFF376480),
              shape: BoxShape.rectangle,
              borderRadius: new BorderRadius.only(
                topRight: Radius.circular(80.0),
                bottomRight: Radius.circular(80.0),
              ),
              boxShadow: <BoxShadow>[
                new BoxShadow(
                  color: Colors.black12,
                  blurRadius: 10.0,
                  offset: new Offset(0.0, .0),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}