I am creating a web panel in flutter and I have a stateless widget. I need to change just an int which is on another file on this behalf my color of fonts is changing.
main.dart
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primaryColor: Color(0xfff00B074),
textTheme: const TextTheme(
bodyText1: TextStyle(
fontSize: 18.0,
fontFamily: 'Barlow-Medium',
color: Color(0xff464255)),
),
),
home: MainScreen(),
);
}
}
main_screen.dart
class MainScreen extends StatelessWidget {
const MainScreen({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Row(
children: [
if (Responsive.isDesktop(context))
Expanded(
// default flex = 1
child: SideMenu(),
),
Expanded(
flex: 5,
child: Container(),
),
],
),
),
);
}
}
And my side menu
class SideMenu extends StatelessWidget {
const SideMenu({
Key? key,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return Drawer(
child: ListView(
children: [
Padding(
padding: const EdgeInsets.only(top: 30, bottom: 15),
child: SvgPicture.asset(
"assets/icon/logo.svg",
),
),
DrawerListTile(
intKey: 1,
title: "Dashboard",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue = 1;
print('asd');
},
),
DrawerListTile(
intKey: 2,
title: "Transaction",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue = 2;
},
),
DrawerListTile(
intKey: 3,
title: "Task",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue = 3;
},
),
DrawerListTile(
intKey: 4,
title: "Documents",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue = 4;
},
),
DrawerListTile(
intKey: 5,
title: "Store",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue = 5;
},
),
DrawerListTile(
intKey: 6,
title: "Notification",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue = 6;
},
),
DrawerListTile(
intKey: 7,
title: "Profile",
svgSrc: "assets/icon/home_deactive.svg",
press: () {},
),
DrawerListTile(
intKey: 8,
title: "Settings",
svgSrc: "assets/icon/home_deactive.svg",
press: () {},
),
],
),
);
}
}
class DrawerListTile extends StatelessWidget {
const DrawerListTile({
Key? key,
// For selecting those three line once press "Command D"
required this.intKey,
required this.title,
required this.svgSrc,
required this.press,
}) : super(key: key);
final String title, svgSrc;
final VoidCallback press;
final int intKey;
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: press,
child: Padding(
padding: const EdgeInsets.only(left: 30, bottom: 30),
child: Container(
child: Row(
children: [
SvgPicture.asset(
svgSrc,
height: 18,
),
SizedBox(
width: 13,
),
Text(
title,
style: sideMenuValue == intKey
? TextStyle(
fontSize: 18.0,
fontFamily: 'Barlow-Medium',
color: Color(0xfff00B074))
: Theme.of(context).textTheme.bodyText1,
),
],
)),
),
);
}
}
You can see on press I am changing the value of sideMenuValue which is not changing because I am using the stateless widget and not want to use the stateful widget.
CodePudding user response：
Change the class that needs to change mode as follows
class HomePage extends StatefullWidget {
const HomePage({
Key? key,
}) : super(key: key);
@override
State<HomePage> createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
..........
);
}
CodePudding user response：
Please refer below code
ValueNotifer & ValueListenableBuilder can be used to hold value and update widget by notifying its listeners and reducing number of times widget tree getting rebuilt.
main.dart file
import 'package:elastic_search/SideMenu.dart';
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
/*
Since sideMenuValue is declared in main.dart file its available globally everywhere in the app
In order to update any value from other files we can make use of ValueNotifer
and to update widget we can use ValueListenableBuilder which updates the particular widget when the value changes (ValueNotifier value)
*/
final ValueNotifier sideMenuValue = ValueNotifier(0);
class MyApp extends StatelessWidget {
MyApp({Key key}) : super(key: key);
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primaryColor: Color(0xfff00B074),
textTheme: const TextTheme(
bodyText1: TextStyle(
fontSize: 18.0,
fontFamily: 'Barlow-Medium',
color: Color(0xff464255)),
),
),
home: MainScreen(),
);
}
}
class MainScreen extends StatelessWidget {
const MainScreen({Key key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Row(
children: [
Expanded(
child: SideMenu(),
),
// Expanded(
// flex: 5,
// child: Container(),
// ),
],
),
),
);
}
}
SideMenu.dart file
import 'package:flutter/material.dart';
import 'package:elastic_search/main.dart';
class SideMenu extends StatelessWidget {
const SideMenu({
Key key,
}) : super(key: key);
@override
Widget build(BuildContext context) {
return Drawer(
child: ListView(
children: [
// Padding(
// padding: const EdgeInsets.only(top: 30, bottom: 15),
// child: SvgPicture.asset(
// "assets/icon/logo.svg",
// ),
// ),
DrawerListTile(
intKey: 1,
title: "Dashboard",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 1;
print('asd');
},
),
DrawerListTile(
intKey: 2,
title: "Transaction",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 2;
},
),
DrawerListTile(
intKey: 3,
title: "Task",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 3;
},
),
DrawerListTile(
intKey: 4,
title: "Documents",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 4;
},
),
DrawerListTile(
intKey: 5,
title: "Store",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 5;
},
),
DrawerListTile(
intKey: 6,
title: "Notification",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 6;
},
),
DrawerListTile(
intKey: 7,
title: "Profile",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 7;
},
),
DrawerListTile(
intKey: 8,
title: "Settings",
svgSrc: "assets/icon/home_deactive.svg",
press: () {
sideMenuValue.value = 8;
},
),
],
),
);
}
}
class DrawerListTile extends StatelessWidget {
const DrawerListTile({
Key key,
// For selecting those three line once press "Command D"
@required this.intKey,
@required this.title,
@required this.svgSrc,
@required this.press,
}) : super(key: key);
final String title, svgSrc;
final VoidCallback press;
final int intKey;
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: press,
child: Padding(
padding: const EdgeInsets.only(left: 30, bottom: 30),
child: Container(
child: Row(
children: [
// SvgPicture.asset(
// svgSrc,
// height: 18,
// ),
SizedBox(
width: 13,
),
/*
In order update widget we can use ValueListenableBuilder which updates the particular widget when the value changes (ValueNotifier value)
*/
ValueListenableBuilder(
valueListenable: sideMenuValue,
builder: (context, snapshot, child) {
return Text(
title,
style: sideMenuValue.value == intKey
? TextStyle(
fontSize: 18.0,
fontFamily: 'Barlow-Medium',
color: Color(0xfff00B074))
: Theme.of(context).textTheme.bodyText1,
);
}),
],
)),
),
);
}
}