使用这段代码，你可以显示菜单，你需要

• • 功能**

void showPopUpMenuAtTap(BuildContext context, TapDownDetails details) {
    showMenu(
      context: context,
      position: RelativeRect.fromLTRB(
        details.globalPosition.dx,
        details.globalPosition.dy,
        details.globalPosition.dx,
        details.globalPosition.dy,
      ),
      items: const [
        PopupMenuItem<String>(value: '1', child: Text('menu option 1')),
        PopupMenuItem<String>(value: '2', child: Text('menu option 2')),
        PopupMenuItem<String>(value: '3', child: Text('menu option 3')),
      ],
    ).then((value) {
      if (value == null) return;

      if (value == "1") {
        //code here
        log("message", name: value);
      } else if (value == "2") {
        //code here
        log("message", name: value);
      } else if (value == "3") {
        //code here
        log("message", name: value);
      }
    });
  }

"你可以这样打电话"

GestureDetector(
          child: const Icon(Icons.menu),
          onTapDown: (details) => showPopUpMenuAtTap(context, details),
        ),

Flutter软件包中的弹出菜单按钮
https://api.flutter.dev/flutter/material/PopupMenuButton-class.html
可以将“图形边框”设置为“RoundedRectangleBorder”。

您需要的是popupmenu，而不是AlertDialog，这里是popupmenu的documantain
有了特征形状，你可以玩的形状和大小...等