flutter設定寬高不生效

給設定寬高的Container包一個父元件（如Center）即可
參考文章-寫了為什麼會這樣
原始碼

class TapboxA extends StatefulWidget {
  TapboxA({Key? key}) : super(key: key);

  @override
  _TapboxAState createState() => _TapboxAState();
}

class _TapboxAState extends State<TapboxA> {
  bool _active = false;

  void _handleTap() {
    setState(() {
      _active = !_active;
    });
  }

  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: _handleTap,
        child: Container(
          child: Center(
            child: Text(
              _active ? 'Active' : 'Inactive',
              style: TextStyle(fontSize: 32.0, color: Colors.white),
            ),
          ),
          width: 200.0,
          height: 200.0,
          decoration: BoxDecoration(
            color: _active ? Colors.lightGreen[700] : Colors.grey[600],
          ),
        ),
    );
  }
}

修改後

class TapboxA extends StatefulWidget {
  TapboxA({Key? key}) : super(key: key);

  @override
  _TapboxAState createState() => _TapboxAState();
}

class _TapboxAState extends State<TapboxA> {
  bool _active = false;

  void _handleTap() {
    setState(() {
      _active = !_active;
    });
  }

  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: _handleTap,
      child: Center(
        child: Container(
          child: Center(
            child: Text(
              _active ? 'Active' : 'Inactive',
              style: TextStyle(fontSize: 32.0, color: Colors.white),
            ),
          ),
          width: 200.0,
          height: 200.0,
          decoration: BoxDecoration(
            color: _active ? Colors.lightGreen[700] : Colors.grey[600],
          ),
        ),
      ),
    );
  }
}