如何在flutter中实现fontSize调整对话框？

class FontSizeDialog extends StatefulWidget {
  @override
  _FontSizeDialogState createState() => _FontSizeDialogState();
}

class _FontSizeDialogState extends State<FontSizeDialog> {
  double _fontSize = 16.0;

  void _updateFontSize(double newSize) {
    setState(() {
      _fontSize = newSize;
    });
  }

  @override
  Widget build(BuildContext context) {
    // 构建对话框的UI
    // ...
  }
}

@override
Widget build(BuildContext context) {
  return AlertDialog(
    title: Text('调整字体大小'),
    content: Slider(
      value: _fontSize,
      min: 12.0,
      max: 24.0,
      onChanged: _updateFontSize,
    ),
    actions: <Widget>[
      FlatButton(
        child: Text('确定'),
        onPressed: () {
          Navigator.of(context).pop();
        },
      ),
    ],
  );
}

void _showFontSizeDialog() {
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return FontSizeDialog();
    },
  );
}