class _MyHomePageState extends State<MyHomePage> {
  int height = 170;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: HeightSlider(
          height: height,
          onChange: (val) => setState(() => height = val),
          unit: 'cm', // optional
        ),
      ),
    );
  }
}