Flutter Get.changeTheme() does not change the app theme (misuse?) - flutter

Question

Here described the simplest/lasiest way to change a color theme of the app. It states:
Please do not use any higher level widget than GetMaterialApp in order to update it.
It appears my understanding of how to use the Get package is not correct.
Tried 2 variants of the code (with or without the commented out line) - the theme does not change.
import 'package:flutter/material.dart';
import 'package:get/get.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return GetMaterialApp(
title: 'ThemeDemo',
// UPDATE: Added 2 lines
theme: ThemeData.light(),
darkTheme: ThemeData.dark(),
themeMode: Get.isDarkMode ? ThemeMode.light : ThemeMode.dark,
home: const MyHomePage(
title: 'Theme Demo',
),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
#override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
actions: <Widget>[
PopupMenuButton<String>(
onSelected: handleClick,
itemBuilder: (BuildContext context) {
return {'Logout', 'Theme'}.map((String choice) {
return PopupMenuItem<String>(
value: choice,
child: Text(choice),
);
}).toList();
},
),
],
),
);
}
void handleClick(String value) {
switch (value) {
case 'Logout':
break;
case 'Theme':
// UPDATE: Uncommented the control
Get.changeTheme(Get.isDarkMode ? ThemeData.light() : ThemeData.dark());
break;
}
}
}
Please, help me to understand the problem and how to use Get to change the theme.
I am very beginner in Flutter, so any constructive critics is welcome!

Answer 1

you should specify the Theme and darkTheme in GetMaterialApp then the themeMode,
like this:
GetMaterialApp(
// your other properties
theme: YourDefaultTHemeHere,
darkTheme: YourDarkThemeHere,
themeMode: Get.isDarkMode ? ThemeMode.light : ThemeMode.dark,
)