Flutter 如何更改 DropDownMenu 的显示方向

要让下拉列表向上移动，您只需将其放在Column的GestureDetector上方.我还改变了一些东西:

• 您不需要ClipRRect a AnimatedConainer具有属性decoration，该属性允许设置BoxDecoration以添加BorderRadius和许多其他内容.
• 此外，不需要Transform-Widget，AnimatedContainer本身就是一个Transform属性.

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

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

class _HomeDropdownMenuState extends State<HomeDropdownMenu> {
  bool _isExpanded = false;

  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        AnimatedContainer(
          duration: const Duration(milliseconds: 300),
          decoration: const BoxDecoration(
            color: Colors.white,
            borderRadius: BorderRadius.only(
              topLeft: Radius.circular(20),
              topRight: Radius.circular(20),
            ),
          ),
          height: _isExpanded
              ? min(MediaQuery.of(context).size.height * 0.5,
                  MediaQuery.of(context).size.height - 80)
              : 0,
          width: double.infinity,
          child: SingleChildScrollView(
            physics: const NeverScrollableScrollPhysics(),
            child: Column(
              children: const [
                Text('option 1'),
                Text('option 2'),
                Text('option 3'),
                Text('option 4'),
                Text('option 5'),
              ],
            ),
          ),
        ),
        GestureDetector(
          onTap: () {
            setState(() {
              _isExpanded = !_isExpanded;
            });
          },
          child: Container(
            color: Colors.blue,
            padding: const EdgeInsets.symmetric(vertical: 10, horizontal: 20),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Center(
                  child: Text(
                    'Menu',
                    style: TextStyle(
                      fontSize: 20,
                      fontWeight: FontWeight.bold,
                    ),
                  ),
                ),
                Icon(
                  _isExpanded
                      ? Icons.expand_more_rounded
                      : Icons.expand_less_rounded,
                  size: 30,
                ),
              ],
            ),
          ),
        ),
      ],
    );
  }
}