this my code
Container(
child: Column(
children: jobProvider.jobs
.map(
(job) => JobTile(job),
)
.toList(),
),
)
how to load this data delay for 3 seconds ? here I display the listview data, before displaying it I want to display, the
return Container(
child: ProfileShimmer(),
);
Should be as easy as this:
import 'package:flutter/material.dart';
class PageWithDelayedView extends StatefulWidget {
const PageWithDelayedView({Key? key}) : super(key: key);
#override
_PageWithDelayedViewState createState() => _PageWithDelayedViewState();
}
class _PageWithDelayedViewState extends State<PageWithDelayedView> {
bool _initialized = false;
#override
void initState() {
super.initState();
// Schedule function call after the widget is ready to display
WidgetsBinding.instance?.addPostFrameCallback((_) {
_initialize();
});
}
void _initialize() {
Future<void>.delayed(const Duration(seconds: 3), () {
if (mounted) { // Check that the widget is still mounted
setState(() {
_initialized = true;
});
}
});
}
#override
Widget build(BuildContext context) {
if (!_initialized) {
return Text('Hold on a bit');
}
return Text('Yay, I\'m ready!');
}
}
Related
i have two screens A and B.In screen A iam calling a function periodically(i.e every 5 seconds).At the time of navigating to screen B i need to stop the function calling and when its back to screen A, the function call should be resumed.
Is there any way to do it?
Navigator doesn't expose the current route.
What you can do instead is use Navigator.popUntil(callback) as popUtil pass to the callback the current Route, which includes it's name and stuff.
final newRouteName = "/NewRoute";
bool isNewRouteSameAsCurrent = false;
Navigator.popUntil(context, (route) {
if (route.settings.name == newRouteName) {
isNewRouteSameAsCurrent = true;
}
return true;
});
if (!isNewRouteSameAsCurrent) {
Navigator.pushNamed(context, newRouteName);
}
Use This bool to check current screen and toggle your function .
From what i see is you can use the Timer class in the widget and manupulate based on your needs, I have created a sample example for you.
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return const MaterialApp(
home: PageOne()
);
}
}
class PageOne extends StatefulWidget {
const PageOne({Key? key}) : super(key: key);
#override
_PageOneState createState() => _PageOneState();
}
class _PageOneState extends State<PageOne> {
Timer? timer;
#override
void initState() {
// TODO: implement initState
super.initState();
timer = Timer.periodic(const Duration(seconds: 2), (timer) {
printMethod("init");
});
}
printMethod(String type){
print("This is the $type print statement ");
}
#override
void dispose() {
super.dispose();
timer?.cancel();
print("First Page timer cancelled");
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: TextButton(onPressed: () async {
timer?.cancel();
var result = await Navigator.push(context, MaterialPageRoute(builder: (context)=> const PageTwo() ));
if(result)
{
timer = Timer.periodic(const Duration(seconds: 2), (timer) {
printMethod("init");
});
}
}, child: const Text("go to next page"),),
),
);
}
}
class PageTwo extends StatefulWidget {
const PageTwo({Key? key}) : super(key: key);
#override
_PageTwoState createState() => _PageTwoState();
}
class _PageTwoState extends State<PageTwo> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Page two"),),
body: Center(
child: TextButton(onPressed: () async {
Navigator.of(context).pop(true);
}, child: const Text("go to prev page"),),
),
);
}
}
Let me know if it works
You can simply use bool to handle this case as follows :
class _ScreenAState extends State<ScreenA> {
bool runPeriodicFun = true;
void periodicFun() {
if (runPeriodicFun) {
//write your periodic logic
}
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: InkWell(
onTap: () {
setState(() {
runPeriodicFun = false;
});
Navigator.push(
context,
MaterialPageRoute(
builder: (BuildContext context) => ScreenB()))
.then((value) {
setState(() {
runPeriodicFun = true;
});
periodicFun();
});
},
child: Container()),
);
}
}
when you go to Screen B then runPeriodicFun set to false and coming back to Screen A runPeriodicFun set to true. So it will use periodicFun block only when runPeriodicFun is true.
You will receive callback in then block in the Navigator.push method.
what i did is that, in timer function i checked the current page is at top of stack by
ModalRoute.of(context)!.isCurrent
what it did is that it will check the page by context which we pass if the page is at top it will continue the timer, if it navigates to another page then the above code will return false.
In false, i just stop the timer.
if(ModalRoute.of(context)!.isCurrent){
//timer running
}else{
_timer?.cancel();
}
so if the page is same timer will perform otherwise it will stop the timer.
Now for resuming the timer, under the build in screen where you called i just called the function from where timer get activated.
Widget build(BuildContext context) {
//call timer function
return SafeArea()}
i think this might solve the problem. if anyone identify any problem please comment it.
I have web api that returns last image taken from database so I wish to make timer to show latest image every few seconds using Flutter and Dart. Ideally I would like to load image, shot it to the user and request new image from server infinitely. My issue is that before new image is displayed, black screen appears so it makes flickering effect. How can I solve it? Here is my code:
import 'dart:async';
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
class TestWidget extends StatefulWidget {
const TestWidget({Key? key}) : super(key: key);
#override
_CameraWidgetState createState() => _CameraWidgetState();
}
class _CameraWidgetState extends State<TestWidget> {
late int a = 1;
final scaffoldKey = GlobalKey<ScaffoldState>();
late bool loaded = false;
late Future futureRecords;
Future getImage() async {
final responses = await http.get(
Uri.parse("https://0465-95-178-160-106.ngrok.io/profile/download?picNum=" +
(a++).toString()),
headers: {
"Accept": "application/json",
"Access-Control_Allow_Origin": "*",
});
if (responses.statusCode == 200) {
return responses.bodyBytes;
} else {
throw Exception('Failed to load image');
}
}
#override
void initState() {
futureRecords = getImage();
Timer.periodic(Duration(seconds: 5), (timer) async {
try {
//await getImage();
setState(() {
futureRecords = getImage();
});
} catch (Ex) {}
});
super.initState();
}
#override
Widget build(BuildContext context) {
return FutureBuilder(
future: futureRecords,
builder: (context, snapshot) {
if (!snapshot.hasData)
return Center(
child: CircularProgressIndicator(),
);
Uint8List bytes = snapshot.data as Uint8List;
return Image.memory(
bytes,
fit: BoxFit.fill,
);
});
}
}
Solution
You wrap your Testwidget with Material or Scaffold,Materialapp widget.You can AnimatedSwitcher widget to avoid that flickering effect or default color
Material(
child: AnimatedSwitcher(
duration: Duration(seconds: 1),
child: widget,
),
);
Before (Flickering)
class MYAppWithFlicker extends StatelessWidget {
const MYAppWithFlicker({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return TestWidget();
}
}
After (Without Flickering)
class MYAppWithoutFlicker extends StatelessWidget {
const MYAppWithoutFlicker({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Material(child: TestWidget());
}
}
Sample Code
import 'dart:async';
import 'dart:typed_data';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart';
void main() {
runApp(MYAppWithoutFlicker());
}
class MYAppWithoutFlicker extends StatelessWidget {
const MYAppWithoutFlicker({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return Material(
color: Colors.lightGreen,
child: TestWidget(),
);
}
}
class MYAppWithFlicker extends StatelessWidget {
const MYAppWithFlicker({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return TestWidget();
}
}
class TestWidget extends StatefulWidget {
const TestWidget({Key? key}) : super(key: key);
#override
_CameraWidgetState createState() => _CameraWidgetState();
}
class _CameraWidgetState extends State<TestWidget> {
late int a = 1;
final scaffoldKey = GlobalKey<ScaffoldState>();
late bool loaded = false;
late Future futureRecords;
Future getImage() async {
var s = "https://0465-95-178-160-106.ngrok.io/profile/download?picNum=" +
(a++).toString();
final responses = await get(
Uri.parse(a % 2 == 0
? "https://images.indianexpress.com/2019/09/toys.jpg"
: "https://ecommerce.ccc2020.fr/wp-content/uploads/2020/10/electronic-gadgets.jpeg"),
headers: {
"Accept": "application/json",
"Access-Control_Allow_Origin": "*",
});
if (responses.statusCode == 200) {
print(responses.bodyBytes);
return responses.bodyBytes;
} else {
throw Exception('Failed to load image');
}
}
#override
void initState() {
futureRecords = getImage();
Timer.periodic(Duration(seconds: 5), (timer) async {
try {
//await getImage();
setState(() {
futureRecords = getImage();
});
} catch (Ex) {}
});
super.initState();
}
#override
Widget build(BuildContext context) {
var widget;
return FutureBuilder(
future: futureRecords,
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.waiting)
widget =
Center(child: CircularProgressIndicator());
else if (snapshot.connectionState == ConnectionState.done) {
Uint8List bytes = snapshot.data as Uint8List;
widget = Image.memory(
bytes,
fit: BoxFit.fill,
);
}
// return AnimatedSwitcher(
// duration: Duration(seconds: 1),
// child: widget,
// );
return Material(
child: AnimatedSwitcher(
duration: Duration(seconds: 1),
child: widget,
),
);
});
}
}
After few days of trying various methods, I found out about gaplessPlayback property in Image.memory and when I set it to true, all magically worked as expected.
In Flutter, can I put FutureBuilder inside a Timer? Is there a way to automatically refresh the GUI using FutureBuilder? Or any other possible way?
I am not sure what is your goal, but if you want to recreate your widget every X seconds with different strings you can use Future.delayed:
import 'package:flutter/material.dart';
import 'dart:async';
class RefreshWidget extends StatefulWidget {
RefreshWidget({Key? key, required this.title}) : super(key: key);
final String title;
#override
_RefreshWidgetState createState() => _RefreshWidgetState();
}
class _RefreshWidgetState extends State<RefreshWidget> {
static List<String> myStrings = ["aaa", "bbb", "ccc", "ddd"];
int i = 0;
String _current = myStrings[0];
void rebuild() {
Future.delayed(Duration(seconds: 3), () {
setState(() {
_current = myStrings[++i % 4];
});
rebuild();
});
}
#override
void initState() {
rebuild();
super.initState();
}
#override
Widget build(BuildContext context) {
return Material(child: Center(child: Text(_current)));
}
}
This package might help to refresh your widget periodically.
https://pub.dev/packages/refreshable_widget
Flexible(
child: RefreshableWidget<num>(
initialValue: challenge.userParticipation!.donePercent,
refreshCall: () async {
final challenge =
await cadoo.getChallengeDetail(
id: widget.challengeId,
);
return challenge.userParticipation!.donePercent;
},
builder: (context, value) {
return DonePercentWidget(
percent: value,
);
},
),
),
FLutter:
How to display video in video_player from the location of path_provider ?
you can copy paste run full code below
In demo, I use getApplicationDocumentsDirectory. you can print full path to check
make sure you have a file located in
/data/user/0/your_proejct_name/app_flutter/Movies/2019-11-08.mp4
code snippet
Future<String> load_path_video() async {
loading = true;
final Directory extDir = await getApplicationDocumentsDirectory();
setState(() {
dirPath = '${extDir.path}/Movies/2019-11-08.mp4';
print(dirPath);
loading = false;
// if I print ($dirPath) I have /data/user/0/com.XXXXX.flutter_video_test/app_flutter/Movies/2019-11-08.mp4
});
}
Container(
padding: const EdgeInsets.all(20),
child: loading
? CircularProgressIndicator()
: NetworkPlayerLifeCycle(
'$dirPath', // with the String dirPath I have error but if I use the same path but write like this /data/user/0/com.XXXXX.flutter_video_test/app_flutter/Movies/2019-11-08.mp4 it's ok ... why ?
(BuildContext context, VideoPlayerController controller) =>
AspectRatioVideo(controller)),
),
working demo
full code
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:io';
import 'package:video_player/video_player.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
String dirPath;
bool loading = false;
Future<String> load_path_video() async {
loading = true;
final Directory extDir = await getApplicationDocumentsDirectory();
setState(() {
dirPath = '${extDir.path}/Movies/2019-11-08.mp4';
print(dirPath);
loading = false;
// if I print ($dirPath) I have /data/user/0/com.XXXXX.flutter_video_test/app_flutter/Movies/2019-11-08.mp4
});
}
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
#override
void initState() {
// TODO: implement initState
load_path_video();
super.initState();
}
#override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
body: ListView(
children: <Widget>[
Container(
padding: const EdgeInsets.all(20),
child: loading
? CircularProgressIndicator()
: NetworkPlayerLifeCycle(
'$dirPath', // with the String dirPath I have error but if I use the same path but write like this /data/user/0/com.XXXXX.flutter_video_test/app_flutter/Movies/2019-11-08.mp4 it's ok ... why ?
(BuildContext context, VideoPlayerController controller) =>
AspectRatioVideo(controller)),
),
],
),
);
}
}
class VideoPlayPause extends StatefulWidget {
VideoPlayPause(this.controller);
final VideoPlayerController controller;
#override
State createState() {
return _VideoPlayPauseState();
}
}
class _VideoPlayPauseState extends State<VideoPlayPause> {
_VideoPlayPauseState() {
listener = () {
setState(() {});
};
}
FadeAnimation imageFadeAnim =
FadeAnimation(child: const Icon(Icons.play_arrow, size: 100.0));
VoidCallback listener;
VideoPlayerController get controller => widget.controller;
#override
void initState() {
super.initState();
controller.addListener(listener);
controller.setVolume(1.0);
controller.play();
}
#override
void deactivate() {
controller.setVolume(0.0);
controller.removeListener(listener);
super.deactivate();
}
#override
Widget build(BuildContext context) {
final List<Widget> children = <Widget>[
GestureDetector(
child: VideoPlayer(controller),
onTap: () {
if (!controller.value.initialized) {
return;
}
if (controller.value.isPlaying) {
imageFadeAnim =
FadeAnimation(child: const Icon(Icons.pause, size: 100.0));
controller.pause();
} else {
imageFadeAnim =
FadeAnimation(child: const Icon(Icons.play_arrow, size: 100.0));
controller.play();
}
},
),
Align(
alignment: Alignment.bottomCenter,
child: VideoProgressIndicator(
controller,
allowScrubbing: true,
),
),
Center(child: imageFadeAnim),
Center(
child: controller.value.isBuffering
? const CircularProgressIndicator()
: null),
];
return Stack(
fit: StackFit.passthrough,
children: children,
);
}
}
class FadeAnimation extends StatefulWidget {
FadeAnimation(
{this.child, this.duration = const Duration(milliseconds: 500)});
final Widget child;
final Duration duration;
#override
_FadeAnimationState createState() => _FadeAnimationState();
}
class _FadeAnimationState extends State<FadeAnimation>
with SingleTickerProviderStateMixin {
AnimationController animationController;
#override
void initState() {
super.initState();
animationController =
AnimationController(duration: widget.duration, vsync: this);
animationController.addListener(() {
if (mounted) {
setState(() {});
}
});
animationController.forward(from: 0.0);
}
#override
void deactivate() {
animationController.stop();
super.deactivate();
}
#override
void didUpdateWidget(FadeAnimation oldWidget) {
super.didUpdateWidget(oldWidget);
if (oldWidget.child != widget.child) {
animationController.forward(from: 0.0);
}
}
#override
void dispose() {
animationController.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return animationController.isAnimating
? Opacity(
opacity: 1.0 - animationController.value,
child: widget.child,
)
: Container();
}
}
typedef Widget VideoWidgetBuilder(
BuildContext context, VideoPlayerController controller);
abstract class PlayerLifeCycle extends StatefulWidget {
PlayerLifeCycle(this.dataSource, this.childBuilder);
final VideoWidgetBuilder childBuilder;
final String dataSource;
}
/// A widget connecting its life cycle to a [VideoPlayerController] using
/// a data source from the network.
class NetworkPlayerLifeCycle extends PlayerLifeCycle {
NetworkPlayerLifeCycle(String dataSource, VideoWidgetBuilder childBuilder)
: super(dataSource, childBuilder);
#override
_NetworkPlayerLifeCycleState createState() => _NetworkPlayerLifeCycleState();
}
/// A widget connecting its life cycle to a [VideoPlayerController] using
/// an asset as data source
class AssetPlayerLifeCycle extends PlayerLifeCycle {
AssetPlayerLifeCycle(String dataSource, VideoWidgetBuilder childBuilder)
: super(dataSource, childBuilder);
#override
_AssetPlayerLifeCycleState createState() => _AssetPlayerLifeCycleState();
}
abstract class _PlayerLifeCycleState extends State<PlayerLifeCycle> {
VideoPlayerController controller;
#override
/// Subclasses should implement [createVideoPlayerController], which is used
/// by this method.
void initState() {
super.initState();
controller = createVideoPlayerController();
controller.addListener(() {
if (controller.value.hasError) {
print(controller.value.errorDescription);
}
});
controller.initialize();
controller.setLooping(true);
controller.play();
}
#override
void deactivate() {
super.deactivate();
}
#override
void dispose() {
controller.dispose();
super.dispose();
}
#override
Widget build(BuildContext context) {
return widget.childBuilder(context, controller);
}
VideoPlayerController createVideoPlayerController();
}
class _NetworkPlayerLifeCycleState extends _PlayerLifeCycleState {
#override
VideoPlayerController createVideoPlayerController() {
return VideoPlayerController.network(widget.dataSource);
}
}
class _AssetPlayerLifeCycleState extends _PlayerLifeCycleState {
#override
VideoPlayerController createVideoPlayerController() {
return VideoPlayerController.asset(widget.dataSource);
}
}
/// A filler card to show the video in a list of scrolling contents.
Widget buildCard(String title) {
return Card(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
ListTile(
leading: const Icon(Icons.airline_seat_flat_angled),
title: Text(title),
),
// TODO(jackson): Remove when deprecation is on stable branch
// ignore: deprecated_member_use
ButtonTheme.bar(
child: ButtonBar(
children: <Widget>[
FlatButton(
child: const Text('BUY TICKETS'),
onPressed: () {
/* ... */
},
),
FlatButton(
child: const Text('SELL TICKETS'),
onPressed: () {
/* ... */
},
),
],
),
),
],
),
);
}
class VideoInListOfCards extends StatelessWidget {
VideoInListOfCards(this.controller);
final VideoPlayerController controller;
#override
Widget build(BuildContext context) {
return ListView(
children: <Widget>[
buildCard("Item a"),
buildCard("Item b"),
buildCard("Item c"),
buildCard("Item d"),
buildCard("Item e"),
buildCard("Item f"),
buildCard("Item g"),
Card(
child: Column(children: <Widget>[
Column(
children: <Widget>[
const ListTile(
leading: Icon(Icons.cake),
title: Text("Video video"),
),
Stack(
alignment: FractionalOffset.bottomRight +
const FractionalOffset(-0.1, -0.1),
children: <Widget>[
AspectRatioVideo(controller),
Image.asset('assets/flutter-mark-square-64.png'),
]),
],
),
])),
buildCard("Item h"),
buildCard("Item i"),
buildCard("Item j"),
buildCard("Item k"),
buildCard("Item l"),
],
);
}
}
class AspectRatioVideo extends StatefulWidget {
AspectRatioVideo(this.controller);
final VideoPlayerController controller;
#override
AspectRatioVideoState createState() => AspectRatioVideoState();
}
class AspectRatioVideoState extends State<AspectRatioVideo> {
VideoPlayerController get controller => widget.controller;
bool initialized = false;
VoidCallback listener;
#override
void initState() {
super.initState();
listener = () {
if (!mounted) {
return;
}
if (initialized != controller.value.initialized) {
initialized = controller.value.initialized;
setState(() {});
}
};
controller.addListener(listener);
}
#override
Widget build(BuildContext context) {
if (initialized) {
return Center(
child: AspectRatio(
aspectRatio: controller.value.aspectRatio,
child: VideoPlayPause(controller),
),
);
} else {
return Container();
}
}
}
I have searched the web for auto refresh widgets and auto refresh future JSON for Flutter but the results all seem to be for pull down refresh.
What I need is like a function that I can call and every minute that said function repeats.
I know I have to integrate something like:
var future = new Future.delayed(const Duration(milliseconds: 10), TracksWidget());
However I am not sure where I need to put it.
import 'dart:async';
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import '../model/track.dart';
class TracksWidget extends StatefulWidget {
#override
_TracksWidgetState createState() => _TracksWidgetState();
}
class _TracksWidgetState extends State<TracksWidget> {
Future<Track> track;
#override
Widget build(BuildContext context) {
double c_width = MediaQuery.of(context).size.width;
return new FutureBuilder<Track>(
future: track,
builder: (context, snapshot) {
if (snapshot.hasData) {
Track track = snapshot.data;
return new Container(
padding: const EdgeInsets.all(16.0),
width: c_width,
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Image.network(track.imageurl, width:200.0, height: 200.0,fit: BoxFit.cover),
Text(track.title),
Text(track.artist),
]),
);
} else if (snapshot.hasError) {
return Text("${snapshot.error}");
}
//By default, show a loading spinner.
return CircularProgressIndicator();
},
);
}
#override
void initState() {
super.initState();
track = fetchTrack();
}
Future<Track> fetchTrack() async {
final response =
await http.get('http://139.59.108.222:2199/rpc/drn1/streaminfo.get');
if (response.statusCode == 200) {
// If the call to the server was successful, parse the JSON.
var responseJson = json.decode(response.body);
// assume there is only one track to display
// SO question mentioned 'display current track'
var track = responseJson['data']
.map((musicFileJson) => Track.fromJson(musicFileJson['track']))
.first;
return track;
} else {
// If that call was not successful, throw an error.
throw Exception('Failed to load post');
}
}
}
The simplest way to do this I have found is to use the Timer function.
If you put the timer into initState it will start when the the app is started.
In the code below, the timer will call the addValue() method every 5 seconds which increases the value by one each time. Just remember to dispose of the timer when you have finished with it.
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Timer timer;
int counter = 0;
#override
void initState() {
super.initState();
timer = Timer.periodic(Duration(seconds: 5), (Timer t) => addValue());
}
void addValue() {
setState(() {
counter++;
});
}
#override
void dispose() {
timer?.cancel();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(counter.toString())
],
),
),
);
}
}