How to scroll the listview or perform any other operation when popupmenu entry appears? - flutter

Question

I have created listView which contains 10 container.I trigger the _showCustomMenu() method while longpress the container to show popupmenu.
But could not scroll the listview when popup menu appears.I want to scroll the listview even when popupmenu appears.
This is my code:
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter/rendering.dart';
void main() => runApp(MyApp());
///
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Popup Menu Usage',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Popup Menu Usage'),
);
}
}
///
class MyHomePage extends StatefulWidget {
///
MyHomePage({Key key, this.title}) : super(key: key);
///
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
var _tapPosition;
void _showCustomMenu() {
final RenderBox overlay = Overlay.of(context).context.findRenderObject();
showMenu(
context: context,
items: <PopupMenuEntry<int>>[PopUpMenuEntry()],
position: RelativeRect.fromRect(
_tapPosition &
const Size(40, 40), // smaller rect, the touch area
Offset.zero & overlay.size // Bigger rect, the entire screen
));
}
void _storePosition(TapDownDetails details) {
_tapPosition = details.globalPosition;
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: GestureDetector(
onTapDown:_storePosition,
onLongPress: (){
_showCustomMenu();
},
child:ListView.builder(
itemCount: 10,
itemBuilder: (context,index) {
return Container(height: 500,child: Center(child: Text(index.toString(),style: TextStyle(fontSize: 16),),),);
},
),
),
);
}
}
///
// ignore: must_be_immutable
class PopUpMenuEntry extends PopupMenuEntry<int> {
#override
double height = 100;
// height doesn't matter, as long as we are not giving
// initialValue to showMenu().
#override
bool represents(int n) => n == 1 || n == -1;
#override
PopUpMenuEntryState createState() => PopUpMenuEntryState();
}
///
class PopUpMenuEntryState extends State<PopUpMenuEntry> {
void _onPressed() {
Navigator.pop(context);
}
#override
Widget build(BuildContext context) {
return Column(
children: <Widget>[
FlatButton(onPressed: _onPressed, child: Text('Copy',style: TextStyle(fontSize: 20),)),
],
);
}
}
This is the Output:
Please help me to solve this or give me suggestion for any other popup widgets to overcome this problem.