单击PopupMenuButton时无法更改图标

Question

我在flutter中为一个基于web的项目使用PopupMenuButton，并试图在单击时更改PopupMenuButton图标。因此，在其初始状态下，它会显示Icons.menu，当打开时，它会关闭Icons.close，一旦再次单击，就会恢复到Icons.mnu。

我尝试过onSelected，当单击它试图更改图标时，它根本不会被调用。

我在文档中使用了一个图标或子图标按钮，并使用onPressed来设置State，但这也不起作用。

当前，单击提升按钮时，不会显示下拉菜单，也不会更新图标。

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
static const String _title = 'Flutter Code Sample';
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: _title,
home: MyStatefulWidget(),
);
}
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({super.key});
@override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
bool menuClicked = true;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: <Widget>[
PointerInterceptor(
intercepting: true,
child:  PopupMenuButton<String>(
offset: const Offset(10.0, 50.0),
color: Colors.black,

child: ElevatedButton(
onPressed: () {
setState(() {
menuClicked = !menuClicked;
});
},
child: Icon((menuClicked = true)
? Icons.menu
: Icons.close),),



itemBuilder: (BuildContext context) =>
<PopupMenuEntry<String>>[

PopupMenuItem(
value: "close",

child: ListTile(
leading: Icon(Icons.close, color: Colors.white),
title: Text('Close',
style: TextStyle(color: Colors.white)),
onTap: () {
Navigator.pop(context);
}),

),

],
),
],
),
),
body: Center(
child: Text('test'),
),
);
}
}

Answer 1

等号将为==

Icon((menuClicked == true) ? Icons.menu : Icons.close),

或者你可以做

Icon(menuClicked ? Icons.menu : Icons.close),

class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({super.key});
@override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
bool menuClicked = false;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: <Widget>[
GestureDetector(
behavior: HitTestBehavior.translucent,
onPanDown: (details) {
setState(() {
menuClicked = true;
});
},
child: PopupMenuButton<String>(
offset: const Offset(10.0, 50.0),
color: Colors.black,
onSelected: (value) {
setState(() {
menuClicked = false;
});
},
padding: EdgeInsets.zero,
onCanceled: () {
setState(() {
menuClicked = false;
});
},
child: Icon(menuClicked ? Icons.close : Icons.menu),
itemBuilder: (BuildContext context) => [
PopupMenuItem(
value: "close",
child: ListTile(
leading: Icon(Icons.close, color: Colors.white),
title: Text(
'Close',
style: TextStyle(color: Colors.white),
),
onTap: () {
Navigator.pop(context);
},
),
),
],
),
),
],
),

);
}
}