How to call a void function everywhere in my Flutter app using InheritedWidget?
Niyazi Toros
I have a main.dart and has a button in center. When user tabs the button it navigate into home.dart page. My home.dart page also has a button on center and when user tabs the button it navigate to details page. The app tree and code is shown below.
I try to implement the "InheritedWidget" in my home.dart so after the home.dart as deep as I go I can call the "void _handleUserInteraction" function using "InheritedWidget". Unluckly I am keep getting error that says:
I/flutter (20715): The getter 'handleOnTap' was called on null.
I/flutter (20715): Receiver: null
I/flutter (20715): Tried calling: handleOnTap
home.dart code:
import 'package:flutter/material.dart';
import 'dart:async';
import 'main.dart';
import 'details.dart';
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Timer timer;
// TODO: 1 - INIT STATE
@override
void initState() {
super.initState();
setState(() {
_initializeTimer();
});
}
// TODO: 3 - INITIALIZE TIMER
void _initializeTimer() {
timer = Timer.periodic(const Duration(minutes: 5), (__) {
_logOutUser();
});
}
// TODO: 4 - LOG OUT USER
void _logOutUser() {
timer.cancel();
Navigator.push(
context, new MaterialPageRoute(builder: (context) => new MyApp()));
}
// TODO: 5 - HANDLE USER INTERACTION
// void _handleUserInteraction([_]) {
void _handleUserInteraction() {
print("+++++++ _handleUserInteraction Header ++++++++");
if (!timer.isActive) {
return;
}
timer.cancel();
_initializeTimer();
print("+++++++ _handleUserInteraction Footer ++++++++");
}
@override
Widget build(BuildContext context) {
return LoginState(
handleOnTap: _handleUserInteraction,
child: GestureDetector(
onTap: _handleUserInteraction,
onDoubleTap: _handleUserInteraction,
onLongPress: _handleUserInteraction,
onTapCancel: _handleUserInteraction,
child: new Scaffold(
appBar: AppBar(
title: Text("HOME PAGE"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'GOTO DETAILS PAGE',
),
new RaisedButton(
child: new Text("Details"),
onPressed: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) => new Details()));
})
],
),
),
)));
}
}
class LoginState extends InheritedWidget {
LoginState({
Key key,
@required Widget child,
@required this.handleOnTap,
}): super(key: key, child: child);
final VoidCallback handleOnTap;
static LoginState of(BuildContext context) {
return context.inheritFromWidgetOfExactType(LoginState);
}
@override
bool updateShouldNotify(LoginState oldWidget) => true;
}
details.dart code:
import 'package:flutter/material.dart';
import 'home.dart';
class Details extends StatefulWidget {
@override
_DetailsState createState() => _DetailsState();
}
class _DetailsState extends State<Details> {
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: LoginState.of(context).handleOnTap,
onDoubleTap: LoginState.of(context).handleOnTap,
onLongPress: LoginState.of(context).handleOnTap,
onTapCancel: LoginState.of(context).handleOnTap,
child: new Scaffold(
appBar: AppBar(
title: Text("Details PAGE"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'Every time Tabed it reset the home timer',
),
],
),
),
));
}
}
Ian Hickson
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Ian Hickson
😸
Niyazi Toros
Thanks Ian, I don't want to use my timer in main.dart. I need to use my timer in home.dart and rest of the tree. So I change my home.dart and the details.dart. The onTap: _callback, is working in home.dart but getting same error on details.dart. In my home.dart I created new MaterialApp. Any idea?
Widget build(BuildContext context) => MaterialApp(
theme: ThemeData(
primarySwatch: Colors.red,
),
home: LoginState(
callback: _handleUserInteraction,
child: Builder(builder: homeScreenBuilder)),
);
}
@override
Widget homeScreenBuilder(BuildContext context) {
Function() _callback = LoginState.of(context).callback;
return GestureDetector(
onTap: _callback,
onDoubleTap: _callback,
onLongPress: _callback,
onTapCancel: _callback,
child: new Scaffold(
appBar: AppBar(
title: Text("HOME PAGE"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'GOTO DETAILS PAGE',
),
new RaisedButton(
child: new Text("Details"),
onPressed: () {
Navigator.push(
context,
new MaterialPageRoute(
builder: (context) => new Details()));
})
],
),
),
));
}
class LoginState extends InheritedWidget {
final Widget child;
final Function() callback;
final Key key;
LoginState({@required this.callback, @required this.child, this.key})
: super(key: key);
@override
bool updateShouldNotify(LoginState oldWidget) {
return true;
}
static LoginState of(BuildContext context) =>
context.inheritFromWidgetOfExactType(LoginState);
}
import 'package:flutter/material.dart';
import 'home.dart';
class Details extends StatefulWidget {
@override
_DetailsState createState() => _DetailsState();
}
class _DetailsState extends State<Details> {
@override
Widget build(BuildContext context) {
Function() _callback = LoginState.of(context).callback;
return GestureDetector(
onTap: _callback,
onDoubleTap: _callback,
onLongPress: _callback,
onTapCancel: _callback,
Benedicte Roussel
Le dim., nov. 25, 2018 à 6:48, Niyazi Toros<niyazi...@gmail.com> a écrit :
--
Niyazi Toros
Benedicte Roussel
hum, I have not enough knowledge of inherited widget but here in your code I think you go too quick. LoginState must be reach first and then it's function used. But my beginner level can not help you further :) sorry about that and may be I am wrong.... but I understand that any class under the tree can inherited from your widget but it is not automatic. Something must state it clearly.... something like final loginState=LoginState.of(context);
Widget build(BuildContext context) {
Function() _callback = LoginState.of(context).callback;Le dim., nov. 25, 2018 à 11:44, Niyazi Toros<niyazi...@gmail.com> a écrit :@Bened I thought the "LoginState.of(context). handleOnTap," sufficient enough to goto inherited widget. Is it possible to give me more detail information regarding to my example?