颤振倒数计时器
Flutter Countdown Timer
我怎样才能将传递的值放入构造中,制作一个四舍五入到第一位小数并显示在我的 RaisedButton 的子文本中的计时器?我试过但没有运气。我设法用一个简单的定时器使回调函数工作,但没有周期性的,也没有在文本中实时更新值...
import 'package:flutter/material.dart';
import 'dart:ui';
import 'dart:async';
class TimerButton extends StatefulWidget {
final Duration timerTastoPremuto;
TimerButton(this.timerTastoPremuto);
@override
_TimerButtonState createState() => _TimerButtonState();
}
class _TimerButtonState extends State<TimerButton> {
@override
Widget build(BuildContext context) {
return Container(
margin: EdgeInsets.all(5.0),
height: 135.0,
width: 135.0,
child: new RaisedButton(
elevation: 100.0,
color: Colors.white.withOpacity(.8),
highlightElevation: 0.0,
onPressed: () {
int _start = widget.timerTastoPremuto.inMilliseconds;
const oneDecimal = const Duration(milliseconds: 100);
Timer _timer = new Timer.periodic(
oneDecimal,
(Timer timer) =>
setState(() {
if (_start < 100) {
_timer.cancel();
} else {
_start = _start - 100;
}
}));
},
splashColor: Colors.red,
highlightColor: Colors.red,
//shape: RoundedRectangleBorder e tutto il resto uguale
shape: BeveledRectangleBorder(
side: BorderSide(color: Colors.black, width: 2.5),
borderRadius: new BorderRadius.circular(15.0)),
child: new Text(
"$_start",
style: new TextStyle(fontFamily: "Minim", fontSize: 50.0),
),
),
);
}
}
这是一个使用 Timer.periodic 的例子:
单击按钮时倒计时从 10
开始到 0
:
import 'dart:async';
[...]
Timer _timer;
int _start = 10;
void startTimer() {
const oneSec = const Duration(seconds: 1);
_timer = new Timer.periodic(
oneSec,
(Timer timer) {
if (_start == 0) {
setState(() {
timer.cancel();
});
} else {
setState(() {
_start--;
});
}
},
);
}
@override
void dispose() {
_timer.cancel();
super.dispose();
}
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text("Timer test")),
body: Column(
children: <Widget>[
RaisedButton(
onPressed: () {
startTimer();
},
child: Text("start"),
),
Text("$_start")
],
),
);
}
结果:
你也可以使用CountdownTimer class from the quiver.async库,用法更简单:
import 'package:quiver/async.dart';
[...]
int _start = 10;
int _current = 10;
void startTimer() {
CountdownTimer countDownTimer = new CountdownTimer(
new Duration(seconds: _start),
new Duration(seconds: 1),
);
var sub = countDownTimer.listen(null);
sub.onData((duration) {
setState(() { _current = _start - duration.elapsed.inSeconds; });
});
sub.onDone(() {
print("Done");
sub.cancel();
});
}
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text("Timer test")),
body: Column(
children: <Widget>[
RaisedButton(
onPressed: () {
startTimer();
},
child: Text("start"),
),
Text("$_current")
],
),
);
}
编辑:对于评论中关于按钮点击行为的问题
上面使用 Timer.periodic
的代码,确实会在每次单击按钮时启动一个新的计时器,并且所有这些计时器都会更新相同的 _start
变量,从而导致计数器减少得更快.
有多种解决方案可以改变这种行为,具体取决于您想要实现的目标:
- 单击后禁用按钮,这样用户就不能再打扰倒计时(可能会在取消计时器后重新启用它)
- 用非 null 条件包裹
Timer.periodic
创建,以便多次单击按钮无效
if (_timer != null) {
_timer = new Timer.periodic(...);
}
- 如果您想在每次点击时重新启动计时器,请取消计时器并重置倒计时:
if (_timer != null) {
_timer.cancel();
_start = 10;
}
_timer = new Timer.periodic(...);
- 如果您希望按钮像 play/pause 按钮一样工作:
if (_timer != null) {
_timer.cancel();
_timer = null;
} else {
_timer = new Timer.periodic(...);
}
您也可以使用这个官方 async package which provides a RestartableTimer class,它从 Timer
扩展并添加了 reset
方法。
因此只需在每次单击按钮时调用 _timer.reset();
。
终于,Codepen 现在支持 Flutter 了!所以这里是一个活生生的例子,这样每个人都可以玩它:https://codepen.io/Yann39/pen/oNjrVOb
我创建了一个 Generic Timer Widget,它可以用来显示任何类型的计时器并且它也很灵活。
此小部件具有以下属性
- secondsRemaining:计时器需要运行秒
的持续时间
- whenTimeExpires: 如果计时器结束需要执行什么操作
- countDownStyle: 你想给定时器的任何一种样式
- countDownFormatter:用户想要显示倒数计时器的方式,例如
hh mm ss
字符串如 01 hours: 20 minutes: 45 seconds
您可以提供默认格式化程序 (formatHHMMSS
),以防您不想从每个地方都提供它。
// 为此提供实现 - formatHHMMSS(duration.inSeconds);
或使用下面我提供的实现。
import 'package:flutter/material.dart';
class CountDownTimer extends StatefulWidget {
const CountDownTimer({
Key key,
int secondsRemaining,
this.countDownTimerStyle,
this.whenTimeExpires,
this.countDownFormatter,
}) : secondsRemaining = secondsRemaining,
super(key: key);
final int secondsRemaining;
final Function whenTimeExpires;
final Function countDownFormatter;
final TextStyle countDownTimerStyle;
State createState() => new _CountDownTimerState();
}
class _CountDownTimerState extends State<CountDownTimer>
with TickerProviderStateMixin {
AnimationController _controller;
Duration duration;
String get timerDisplayString {
Duration duration = _controller.duration * _controller.value;
return widget.countDownFormatter != null
? widget.countDownFormatter(duration.inSeconds)
: formatHHMMSS(duration.inSeconds);
// In case user doesn't provide formatter use the default one
// for that create a method which will be called formatHHMMSS or whatever you like
}
@override
void initState() {
super.initState();
duration = new Duration(seconds: widget.secondsRemaining);
_controller = new AnimationController(
vsync: this,
duration: duration,
);
_controller.reverse(from: widget.secondsRemaining.toDouble());
_controller.addStatusListener((status) {
if (status == AnimationStatus.completed || status == AnimationStatus.dismissed) {
widget.whenTimeExpires();
}
});
}
@override
void didUpdateWidget(CountDownTimer oldWidget) {
if (widget.secondsRemaining != oldWidget.secondsRemaining) {
setState(() {
duration = new Duration(seconds: widget.secondsRemaining);
_controller.dispose();
_controller = new AnimationController(
vsync: this,
duration: duration,
);
_controller.reverse(from: widget.secondsRemaining.toDouble());
_controller.addStatusListener((status) {
if (status == AnimationStatus.completed) {
widget.whenTimeExpires();
} else if (status == AnimationStatus.dismissed) {
print("Animation Complete");
}
});
});
}
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return new Center(
child: AnimatedBuilder(
animation: _controller,
builder: (_, Widget child) {
return Text(
timerDisplayString,
style: widget.countDownTimerStyle,
);
}));
}
}
用法:
Container(
width: 60.0,
padding: EdgeInsets.only(top: 3.0, right: 4.0),
child: CountDownTimer(
secondsRemaining: 30,
whenTimeExpires: () {
setState(() {
hasTimerStopped = true;
});
},
countDownTimerStyle: TextStyle(
color: Color(0XFFf5a623),
fontSize: 17.0,
height: 1.2,
),
),
)
格式HHMMSS的示例:
String formatHHMMSS(int seconds) {
int hours = (seconds / 3600).truncate();
seconds = (seconds % 3600).truncate();
int minutes = (seconds / 60).truncate();
String hoursStr = (hours).toString().padLeft(2, '0');
String minutesStr = (minutes).toString().padLeft(2, '0');
String secondsStr = (seconds % 60).toString().padLeft(2, '0');
if (hours == 0) {
return "$minutesStr:$secondsStr";
}
return "$hoursStr:$minutesStr:$secondsStr";
}
以上代码的空安全版本
import 'package:flutter/material.dart';
class CountDownTimer extends StatefulWidget {
const CountDownTimer({
Key? key,
required this.secondsRemaining,
required this.whenTimeExpires,
this.countDownFormatter,
this.countDownTimerStyle,
}) : super(key: key);
final int secondsRemaining;
final VoidCallback whenTimeExpires;
final TextStyle? countDownTimerStyle;
final Function(int seconds)? countDownFormatter;
@override
State createState() => _CountDownTimerState();
}
class _CountDownTimerState extends State<CountDownTimer>
with TickerProviderStateMixin {
late final AnimationController _controller;
late final Duration duration;
String get timerDisplayString {
final duration = _controller.duration! * _controller.value;
if (widget.countDownFormatter != null) {
return widget.countDownFormatter!(duration.inSeconds) as String;
} else {
return formatHHMMSS(duration.inSeconds);
}
}
String formatHHMMSS(int seconds) {
final hours = (seconds / 3600).truncate();
seconds = (seconds % 3600).truncate();
final minutes = (seconds / 60).truncate();
final hoursStr = (hours).toString().padLeft(2, '0');
final minutesStr = (minutes).toString().padLeft(2, '0');
final secondsStr = (seconds % 60).toString().padLeft(2, '0');
if (hours == 0) {
return '$minutesStr:$secondsStr';
}
return '$hoursStr:$minutesStr:$secondsStr';
}
@override
void initState() {
super.initState();
duration = Duration(seconds: widget.secondsRemaining);
_controller = AnimationController(
vsync: this,
duration: duration,
);
_controller
..reverse(from: widget.secondsRemaining.toDouble())
..addStatusListener((status) {
if (status == AnimationStatus.completed ||
status == AnimationStatus.dismissed) {
widget.whenTimeExpires();
}
});
}
@override
void didUpdateWidget(CountDownTimer oldWidget) {
super.didUpdateWidget(oldWidget);
if (widget.secondsRemaining != oldWidget.secondsRemaining) {
setState(() {
duration = Duration(seconds: widget.secondsRemaining);
_controller.dispose();
_controller = AnimationController(
vsync: this,
duration: duration,
);
_controller
..reverse(from: widget.secondsRemaining.toDouble())
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
widget.whenTimeExpires();
}
});
});
}
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Center(
child: AnimatedBuilder(
animation: _controller,
builder: (_, Widget? child) {
return Text(
timerDisplayString,
style: widget.countDownTimerStyle,
);
},
),
);
}
}
一行倒计时
CountdownTimer(Duration(seconds: 5), Duration(seconds: 1)).listen((data){
})..onData((data){
print('data $data');
})..onDone((){
print('onDone.........');
});
没有直接回答你的问题。但对那些想在一段时间后开始做某事的人有帮助。
Future.delayed(Duration(seconds: 1), () {
print('yo hey');
});
如果您只需要一个简单的倒计时计时器,这是一个很好的替代方法,而不是安装一个包。编码愉快!
countDownTimer() async {
int timerCount;
for (int x = 5; x > 0; x--) {
await Future.delayed(Duration(seconds: 1)).then((_) {
setState(() {
timerCount -= 1;
});
});
}
}
这是我的计时器小部件,与问题无关,但可能对某人有所帮助。
import 'dart:async';
import 'package:flutter/material.dart';
class OtpTimer extends StatefulWidget {
@override
_OtpTimerState createState() => _OtpTimerState();
}
class _OtpTimerState extends State<OtpTimer> {
final interval = const Duration(seconds: 1);
final int timerMaxSeconds = 60;
int currentSeconds = 0;
String get timerText =>
'${((timerMaxSeconds - currentSeconds) ~/ 60).toString().padLeft(2, '0')}: ${((timerMaxSeconds - currentSeconds) % 60).toString().padLeft(2, '0')}';
startTimeout([int milliseconds]) {
var duration = interval;
Timer.periodic(duration, (timer) {
setState(() {
print(timer.tick);
currentSeconds = timer.tick;
if (timer.tick >= timerMaxSeconds) timer.cancel();
});
});
}
@override
void initState() {
startTimeout();
super.initState();
}
@override
Widget build(BuildContext context) {
return Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Icon(Icons.timer),
SizedBox(
width: 5,
),
Text(timerText)
],
);
}
}
你会得到这样的东西
我正在使用 https://pub.dev/packages/flutter_countdown_timer
依赖项:
flutter_countdown_timer: ^1.0.0
$ flutter pub get
CountdownTimer(endTime: 1594829147719)
1594829147719 是以毫秒为单位的时间戳
晚会有点晚了,但你们为什么不试试 animation.No 我不是要你管理动画控制器并处理掉它们等等,这里有一个 built-in 小部件那叫 TweenAnimationBuilder。您可以在任何类型的值之间设置动画,这是一个持续时间 class
的示例
TweenAnimationBuilder<Duration>(
duration: Duration(minutes: 3),
tween: Tween(begin: Duration(minutes: 3), end: Duration.zero),
onEnd: () {
print('Timer ended');
},
builder: (BuildContext context, Duration value, Widget? child) {
final minutes = value.inMinutes;
final seconds = value.inSeconds % 60;
return Padding(
padding: const EdgeInsets.symmetric(vertical: 5),
child: Text('$minutes:$seconds',
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.black,
fontWeight: FontWeight.bold,
fontSize: 30)));
}),
并且您还会收到 onEnd 回调,它会在动画完成时通知您;
这是输出
你可以使用这个插件timer_builder
timer_builder 根据预定、定期或动态生成的时间事件自行重建的小部件。
例子
定期重建
import 'package:timer_builder/timer_builder.dart';
class ClockWidget extends StatelessWidget {
@override
Widget build(BuildContext context) {
return TimerBuilder.periodic(Duration(seconds: 1),
builder: (context) {
return Text("${DateTime.now()}");
}
);
}
}
按计划重建
import 'package:timer_builder/timer_builder.dart';
class StatusIndicator extends StatelessWidget {
final DateTime startTime;
final DateTime endTime;
StatusIndicator(this.startTime, this.endTime);
@override
Widget build(BuildContext context) {
return TimerBuilder.scheduled([startTime, endTime],
builder: (context) {
final now = DateTime.now();
final started = now.compareTo(startTime) >= 0;
final ended = now.compareTo(endTime) >= 0;
return Text(started ? ended ? "Ended": "Started": "Not Started");
}
);
}
}
已经提供了很多答案。我建议一个捷径-
使用这个包Custom_timer
将此添加到您的包的 pubspec.yaml 文件中:
dependencies:
custom_timer: ^0.0.3
(使用最新版本)
而且实施起来非常简单
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
appBar: AppBar(
title: Text("CustomTimer example"),
),
body: Center(
child: CustomTimer(
from: Duration(hours: 12),
to: Duration(hours: 0),
onBuildAction: CustomTimerAction.auto_start,
builder: (CustomTimerRemainingTime remaining) {
return Text(
"${remaining.hours}:${remaining.minutes}:${remaining.seconds}",
style: TextStyle(fontSize: 30.0),
);
},
),
),
),
);
}
import 'dart:async';
import 'package:flutter/material.dart';
class CustomTimer extends StatefulWidget {
@override
_CustomTimerState createState() => _CustomTimerState();
}
class _CustomTimerState extends State<CustomTimer> {
final _maxSeconds = 61;
int _currentSecond = 0;
Timer _timer;
String get _timerText {
final secondsPerMinute = 60;
final secondsLeft = _maxSeconds - _currentSecond;
final formattedMinutesLeft =
(secondsLeft ~/ secondsPerMinute).toString().padLeft(2, '0');
final formattedSecondsLeft =
(secondsLeft % secondsPerMinute).toString().padLeft(2, '0');
print('$formattedMinutesLeft : $formattedSecondsLeft');
return '$formattedMinutesLeft : $formattedSecondsLeft';
}
@override
void initState() {
super.initState();
_startTimer();
}
@override
void dispose() {
_timer.cancel();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Icon(Icons.timer),
Text(_timerText),
],
),
),
);
}
void _startTimer() {
final duration = Duration(seconds: 1);
_timer = Timer.periodic(duration, (Timer timer) {
setState(() {
_currentSecond = timer.tick;
if (timer.tick >= _maxSeconds) timer.cancel();
});
});
}
}
要以这种格式 hh:mm:ss 显示您的总秒数,您可以使用以下方法:
String getDuration(int totalSeconds) {
String seconds = (totalSeconds % 60).toInt().toString().padLeft(2, '0');
String minutes =
((totalSeconds / 60) % 60).toInt().toString().padLeft(2, '0');
String hours = (totalSeconds ~/ 3600).toString().padLeft(2, '0');
return "$hours\:$minutes\:$seconds";
}
我已经创建了一个没有任何插件的神奇计时器,在这里您还可以获得倒数计时器。
并且不要忘记在按下后退时停止计时器。
这是我的计时器完整项目的 link。
*Hope this will help someone. Thank you.
*
import 'dart:async';
import 'package:flutter/material.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(
primarySwatch: Colors.blue,
),
home: AttendanceScreen(),
);
}
}
class AttendanceScreen extends StatefulWidget {
AttendanceScreen();
@override
_AttendanceScreenState createState() => _AttendanceScreenState();
}
class _AttendanceScreenState extends State<AttendanceScreen> {
static var countdownDuration = Duration(minutes: 10);
static var countdownDuration1 = Duration(minutes: 10);
Duration duration = Duration();
Duration duration1 = Duration();
Timer? timer;
Timer? timer1;
bool countDown = true;
bool countDown1 = true;
@override
void initState() {
var hours;
var mints;
var secs;
hours = int.parse("00");
mints = int.parse("00");
secs = int.parse("00");
countdownDuration = Duration(hours: hours, minutes: mints, seconds: secs);
startTimer();
reset();
var hours1;
var mints1;
var secs1;
hours1 = int.parse("10");
mints1 = int.parse("00");
secs1 = int.parse("00");
countdownDuration1 =
Duration(hours: hours1, minutes: mints1, seconds: secs1);
startTimer1();
reset1();
super.initState();
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onWillPop,
child: Scaffold(
appBar: AppBar(
title: Text("Timer Example"),
leading: IconButton(
icon: Icon(Icons.arrow_back_ios),
color: Colors.white,
onPressed: () {
_onWillPop();
},
),
),
body: Container(
color: Colors.black12,
width: double.infinity,
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
SizedBox(
height: 20,
),
Text(
"Timer",
style: TextStyle(fontSize: 25),
),
Container(
margin: EdgeInsets.only(top: 30, bottom: 30),
child: buildTime()),
SizedBox(
height: 20,
),
Text(
"Count down timer",
style: TextStyle(fontSize: 25),
),
Container(
margin: EdgeInsets.only(top: 30, bottom: 30),
child: buildTime1()),
]),
),
),
);
}
Future<bool> _onWillPop() async {
final isRunning = timer == null ? false : timer!.isActive;
if (isRunning) {
timer!.cancel();
}
Navigator.of(context, rootNavigator: true).pop(context);
return true;
}
void reset() {
if (countDown) {
setState(() => duration = countdownDuration);
} else {
setState(() => duration = Duration());
}
}
void reset1() {
if (countDown) {
setState(() => duration1 = countdownDuration1);
} else {
setState(() => duration1 = Duration());
}
}
void startTimer() {
timer = Timer.periodic(Duration(seconds: 1), (_) => addTime());
}
void startTimer1() {
timer = Timer.periodic(Duration(seconds: 1), (_) => addTime1());
}
void addTime() {
final addSeconds = 1;
setState(() {
final seconds = duration.inSeconds + addSeconds;
if (seconds < 0) {
timer?.cancel();
} else {
duration = Duration(seconds: seconds);
}
});
}
void addTime1() {
final addSeconds = 1;
setState(() {
final seconds = duration1.inSeconds - addSeconds;
if (seconds < 0) {
timer1?.cancel();
} else {
duration1 = Duration(seconds: seconds);
}
});
}
Widget buildTime() {
String twoDigits(int n) => n.toString().padLeft(2, '0');
final hours = twoDigits(duration.inHours);
final minutes = twoDigits(duration.inMinutes.remainder(60));
final seconds = twoDigits(duration.inSeconds.remainder(60));
return Row(mainAxisAlignment: MainAxisAlignment.center, children: [
buildTimeCard(time: hours, header: 'HOURS'),
SizedBox(
width: 8,
),
buildTimeCard(time: minutes, header: 'MINUTES'),
SizedBox(
width: 8,
),
buildTimeCard(time: seconds, header: 'SECONDS'),
]);
}
Widget buildTime1() {
String twoDigits(int n) => n.toString().padLeft(2, '0');
final hours = twoDigits(duration1.inHours);
final minutes = twoDigits(duration1.inMinutes.remainder(60));
final seconds = twoDigits(duration1.inSeconds.remainder(60));
return Row(mainAxisAlignment: MainAxisAlignment.center, children: [
buildTimeCard(time: hours, header: 'HOURS'),
SizedBox(
width: 8,
),
buildTimeCard(time: minutes, header: 'MINUTES'),
SizedBox(
width: 8,
),
buildTimeCard(time: seconds, header: 'SECONDS'),
]);
}
Widget buildTimeCard({required String time, required String header}) =>
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
padding: EdgeInsets.all(8),
decoration: BoxDecoration(
color: Colors.white, borderRadius: BorderRadius.circular(20)),
child: Text(
time,
style: TextStyle(
fontWeight: FontWeight.bold,
color: Colors.black,
fontSize: 50),
),
),
SizedBox(
height: 24,
),
Text(header, style: TextStyle(color: Colors.black45)),
],
);
}
import 'package:rxdart/rxdart.dart';
final BehaviorSubject<int> resendTimeController = BehaviorSubject<int>();
static const timerDuration = 90;
int resendTimer = 0;
Timer? timer;
void startTimer() {
timer?.cancel();
resendTimer = timerDuration;
timer = Timer.periodic(const Duration(seconds: 1), (timer) {
if (resendTimer > 0) {
resendTimer--;
resendTimeController.add(resendTimer);
if (resendTimer == 0) {
timer.cancel();
}
}
});
}
and use intl this
StreamBuilder<int>(
stream: _bloc.resendTimeController,
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Container();
}
final DateTime date = DateTime.fromMillisecondsSinceEpoch(snapshot.data! * 1000);
return GestureDetector(
onTap: () {
if (snapshot.data == 0) {
_bloc.resendCode();
}
},
child: Text(
snapshot.data! > 0 ? 'Resend code ${DateFormat('mm:ss').format(date)}' : 'Resend SMS',
),
);
},
),
import 'package:async/async.dart';
late CancelableOperation? cancellableOperation;
int counter = 5;
StatefulBuilder(
builder: (context, setState) {
if (counter > 0) {
cancellableOperation = CancelableOperation.fromFuture(
Future.delayed(const Duration(seconds: 1)),
onCancel: () => {},
);
cancellableOperation?.value.whenComplete(() => setState(() => counter--));
return buildButton(
text: 'Wait($counter)',
textColor: getTextColor,
backgroundColor: Colors.grey.withOpacity(0.5),
onPressed: () {},
);
}
return buildButton(
text: 'Complete',
textColor: Colors.green,
backgroundColor: Colors.greenAccent.withOpacity(0.5),
onPressed: () {},
);
},
)
我为对话框的完成按钮做了类似的事情。在显示完成按钮之前,它计数 5 秒。但如果您在计数完成前关闭对话框或页面,请不要忘记调用 cancellableOperation?.cancel()
。
我怎样才能将传递的值放入构造中,制作一个四舍五入到第一位小数并显示在我的 RaisedButton 的子文本中的计时器?我试过但没有运气。我设法用一个简单的定时器使回调函数工作,但没有周期性的,也没有在文本中实时更新值...
import 'package:flutter/material.dart';
import 'dart:ui';
import 'dart:async';
class TimerButton extends StatefulWidget {
final Duration timerTastoPremuto;
TimerButton(this.timerTastoPremuto);
@override
_TimerButtonState createState() => _TimerButtonState();
}
class _TimerButtonState extends State<TimerButton> {
@override
Widget build(BuildContext context) {
return Container(
margin: EdgeInsets.all(5.0),
height: 135.0,
width: 135.0,
child: new RaisedButton(
elevation: 100.0,
color: Colors.white.withOpacity(.8),
highlightElevation: 0.0,
onPressed: () {
int _start = widget.timerTastoPremuto.inMilliseconds;
const oneDecimal = const Duration(milliseconds: 100);
Timer _timer = new Timer.periodic(
oneDecimal,
(Timer timer) =>
setState(() {
if (_start < 100) {
_timer.cancel();
} else {
_start = _start - 100;
}
}));
},
splashColor: Colors.red,
highlightColor: Colors.red,
//shape: RoundedRectangleBorder e tutto il resto uguale
shape: BeveledRectangleBorder(
side: BorderSide(color: Colors.black, width: 2.5),
borderRadius: new BorderRadius.circular(15.0)),
child: new Text(
"$_start",
style: new TextStyle(fontFamily: "Minim", fontSize: 50.0),
),
),
);
}
}
这是一个使用 Timer.periodic 的例子:
单击按钮时倒计时从 10
开始到 0
:
import 'dart:async';
[...]
Timer _timer;
int _start = 10;
void startTimer() {
const oneSec = const Duration(seconds: 1);
_timer = new Timer.periodic(
oneSec,
(Timer timer) {
if (_start == 0) {
setState(() {
timer.cancel();
});
} else {
setState(() {
_start--;
});
}
},
);
}
@override
void dispose() {
_timer.cancel();
super.dispose();
}
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text("Timer test")),
body: Column(
children: <Widget>[
RaisedButton(
onPressed: () {
startTimer();
},
child: Text("start"),
),
Text("$_start")
],
),
);
}
结果:
你也可以使用CountdownTimer class from the quiver.async库,用法更简单:
import 'package:quiver/async.dart';
[...]
int _start = 10;
int _current = 10;
void startTimer() {
CountdownTimer countDownTimer = new CountdownTimer(
new Duration(seconds: _start),
new Duration(seconds: 1),
);
var sub = countDownTimer.listen(null);
sub.onData((duration) {
setState(() { _current = _start - duration.elapsed.inSeconds; });
});
sub.onDone(() {
print("Done");
sub.cancel();
});
}
Widget build(BuildContext context) {
return new Scaffold(
appBar: AppBar(title: Text("Timer test")),
body: Column(
children: <Widget>[
RaisedButton(
onPressed: () {
startTimer();
},
child: Text("start"),
),
Text("$_current")
],
),
);
}
编辑:对于评论中关于按钮点击行为的问题
上面使用 Timer.periodic
的代码,确实会在每次单击按钮时启动一个新的计时器,并且所有这些计时器都会更新相同的 _start
变量,从而导致计数器减少得更快.
有多种解决方案可以改变这种行为,具体取决于您想要实现的目标:
- 单击后禁用按钮,这样用户就不能再打扰倒计时(可能会在取消计时器后重新启用它)
- 用非 null 条件包裹
Timer.periodic
创建,以便多次单击按钮无效
if (_timer != null) {
_timer = new Timer.periodic(...);
}
- 如果您想在每次点击时重新启动计时器,请取消计时器并重置倒计时:
if (_timer != null) {
_timer.cancel();
_start = 10;
}
_timer = new Timer.periodic(...);
- 如果您希望按钮像 play/pause 按钮一样工作:
if (_timer != null) {
_timer.cancel();
_timer = null;
} else {
_timer = new Timer.periodic(...);
}
您也可以使用这个官方 async package which provides a RestartableTimer class,它从 Timer
扩展并添加了 reset
方法。
因此只需在每次单击按钮时调用 _timer.reset();
。
终于,Codepen 现在支持 Flutter 了!所以这里是一个活生生的例子,这样每个人都可以玩它:https://codepen.io/Yann39/pen/oNjrVOb
我创建了一个 Generic Timer Widget,它可以用来显示任何类型的计时器并且它也很灵活。
此小部件具有以下属性
- secondsRemaining:计时器需要运行秒 的持续时间
- whenTimeExpires: 如果计时器结束需要执行什么操作
- countDownStyle: 你想给定时器的任何一种样式
- countDownFormatter:用户想要显示倒数计时器的方式,例如
hh mm ss
字符串如01 hours: 20 minutes: 45 seconds
您可以提供默认格式化程序 (formatHHMMSS
),以防您不想从每个地方都提供它。
// 为此提供实现 - formatHHMMSS(duration.inSeconds);
或使用下面我提供的实现。
import 'package:flutter/material.dart';
class CountDownTimer extends StatefulWidget {
const CountDownTimer({
Key key,
int secondsRemaining,
this.countDownTimerStyle,
this.whenTimeExpires,
this.countDownFormatter,
}) : secondsRemaining = secondsRemaining,
super(key: key);
final int secondsRemaining;
final Function whenTimeExpires;
final Function countDownFormatter;
final TextStyle countDownTimerStyle;
State createState() => new _CountDownTimerState();
}
class _CountDownTimerState extends State<CountDownTimer>
with TickerProviderStateMixin {
AnimationController _controller;
Duration duration;
String get timerDisplayString {
Duration duration = _controller.duration * _controller.value;
return widget.countDownFormatter != null
? widget.countDownFormatter(duration.inSeconds)
: formatHHMMSS(duration.inSeconds);
// In case user doesn't provide formatter use the default one
// for that create a method which will be called formatHHMMSS or whatever you like
}
@override
void initState() {
super.initState();
duration = new Duration(seconds: widget.secondsRemaining);
_controller = new AnimationController(
vsync: this,
duration: duration,
);
_controller.reverse(from: widget.secondsRemaining.toDouble());
_controller.addStatusListener((status) {
if (status == AnimationStatus.completed || status == AnimationStatus.dismissed) {
widget.whenTimeExpires();
}
});
}
@override
void didUpdateWidget(CountDownTimer oldWidget) {
if (widget.secondsRemaining != oldWidget.secondsRemaining) {
setState(() {
duration = new Duration(seconds: widget.secondsRemaining);
_controller.dispose();
_controller = new AnimationController(
vsync: this,
duration: duration,
);
_controller.reverse(from: widget.secondsRemaining.toDouble());
_controller.addStatusListener((status) {
if (status == AnimationStatus.completed) {
widget.whenTimeExpires();
} else if (status == AnimationStatus.dismissed) {
print("Animation Complete");
}
});
});
}
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return new Center(
child: AnimatedBuilder(
animation: _controller,
builder: (_, Widget child) {
return Text(
timerDisplayString,
style: widget.countDownTimerStyle,
);
}));
}
}
用法:
Container(
width: 60.0,
padding: EdgeInsets.only(top: 3.0, right: 4.0),
child: CountDownTimer(
secondsRemaining: 30,
whenTimeExpires: () {
setState(() {
hasTimerStopped = true;
});
},
countDownTimerStyle: TextStyle(
color: Color(0XFFf5a623),
fontSize: 17.0,
height: 1.2,
),
),
)
格式HHMMSS的示例:
String formatHHMMSS(int seconds) {
int hours = (seconds / 3600).truncate();
seconds = (seconds % 3600).truncate();
int minutes = (seconds / 60).truncate();
String hoursStr = (hours).toString().padLeft(2, '0');
String minutesStr = (minutes).toString().padLeft(2, '0');
String secondsStr = (seconds % 60).toString().padLeft(2, '0');
if (hours == 0) {
return "$minutesStr:$secondsStr";
}
return "$hoursStr:$minutesStr:$secondsStr";
}
以上代码的空安全版本
import 'package:flutter/material.dart';
class CountDownTimer extends StatefulWidget {
const CountDownTimer({
Key? key,
required this.secondsRemaining,
required this.whenTimeExpires,
this.countDownFormatter,
this.countDownTimerStyle,
}) : super(key: key);
final int secondsRemaining;
final VoidCallback whenTimeExpires;
final TextStyle? countDownTimerStyle;
final Function(int seconds)? countDownFormatter;
@override
State createState() => _CountDownTimerState();
}
class _CountDownTimerState extends State<CountDownTimer>
with TickerProviderStateMixin {
late final AnimationController _controller;
late final Duration duration;
String get timerDisplayString {
final duration = _controller.duration! * _controller.value;
if (widget.countDownFormatter != null) {
return widget.countDownFormatter!(duration.inSeconds) as String;
} else {
return formatHHMMSS(duration.inSeconds);
}
}
String formatHHMMSS(int seconds) {
final hours = (seconds / 3600).truncate();
seconds = (seconds % 3600).truncate();
final minutes = (seconds / 60).truncate();
final hoursStr = (hours).toString().padLeft(2, '0');
final minutesStr = (minutes).toString().padLeft(2, '0');
final secondsStr = (seconds % 60).toString().padLeft(2, '0');
if (hours == 0) {
return '$minutesStr:$secondsStr';
}
return '$hoursStr:$minutesStr:$secondsStr';
}
@override
void initState() {
super.initState();
duration = Duration(seconds: widget.secondsRemaining);
_controller = AnimationController(
vsync: this,
duration: duration,
);
_controller
..reverse(from: widget.secondsRemaining.toDouble())
..addStatusListener((status) {
if (status == AnimationStatus.completed ||
status == AnimationStatus.dismissed) {
widget.whenTimeExpires();
}
});
}
@override
void didUpdateWidget(CountDownTimer oldWidget) {
super.didUpdateWidget(oldWidget);
if (widget.secondsRemaining != oldWidget.secondsRemaining) {
setState(() {
duration = Duration(seconds: widget.secondsRemaining);
_controller.dispose();
_controller = AnimationController(
vsync: this,
duration: duration,
);
_controller
..reverse(from: widget.secondsRemaining.toDouble())
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
widget.whenTimeExpires();
}
});
});
}
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Center(
child: AnimatedBuilder(
animation: _controller,
builder: (_, Widget? child) {
return Text(
timerDisplayString,
style: widget.countDownTimerStyle,
);
},
),
);
}
}
一行倒计时
CountdownTimer(Duration(seconds: 5), Duration(seconds: 1)).listen((data){
})..onData((data){
print('data $data');
})..onDone((){
print('onDone.........');
});
没有直接回答你的问题。但对那些想在一段时间后开始做某事的人有帮助。
Future.delayed(Duration(seconds: 1), () {
print('yo hey');
});
如果您只需要一个简单的倒计时计时器,这是一个很好的替代方法,而不是安装一个包。编码愉快!
countDownTimer() async {
int timerCount;
for (int x = 5; x > 0; x--) {
await Future.delayed(Duration(seconds: 1)).then((_) {
setState(() {
timerCount -= 1;
});
});
}
}
这是我的计时器小部件,与问题无关,但可能对某人有所帮助。
import 'dart:async';
import 'package:flutter/material.dart';
class OtpTimer extends StatefulWidget {
@override
_OtpTimerState createState() => _OtpTimerState();
}
class _OtpTimerState extends State<OtpTimer> {
final interval = const Duration(seconds: 1);
final int timerMaxSeconds = 60;
int currentSeconds = 0;
String get timerText =>
'${((timerMaxSeconds - currentSeconds) ~/ 60).toString().padLeft(2, '0')}: ${((timerMaxSeconds - currentSeconds) % 60).toString().padLeft(2, '0')}';
startTimeout([int milliseconds]) {
var duration = interval;
Timer.periodic(duration, (timer) {
setState(() {
print(timer.tick);
currentSeconds = timer.tick;
if (timer.tick >= timerMaxSeconds) timer.cancel();
});
});
}
@override
void initState() {
startTimeout();
super.initState();
}
@override
Widget build(BuildContext context) {
return Row(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Icon(Icons.timer),
SizedBox(
width: 5,
),
Text(timerText)
],
);
}
}
你会得到这样的东西
我正在使用 https://pub.dev/packages/flutter_countdown_timer
依赖项: flutter_countdown_timer: ^1.0.0
$ flutter pub get
CountdownTimer(endTime: 1594829147719)
1594829147719 是以毫秒为单位的时间戳
晚会有点晚了,但你们为什么不试试 animation.No 我不是要你管理动画控制器并处理掉它们等等,这里有一个 built-in 小部件那叫 TweenAnimationBuilder。您可以在任何类型的值之间设置动画,这是一个持续时间 class
的示例TweenAnimationBuilder<Duration>(
duration: Duration(minutes: 3),
tween: Tween(begin: Duration(minutes: 3), end: Duration.zero),
onEnd: () {
print('Timer ended');
},
builder: (BuildContext context, Duration value, Widget? child) {
final minutes = value.inMinutes;
final seconds = value.inSeconds % 60;
return Padding(
padding: const EdgeInsets.symmetric(vertical: 5),
child: Text('$minutes:$seconds',
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.black,
fontWeight: FontWeight.bold,
fontSize: 30)));
}),
并且您还会收到 onEnd 回调,它会在动画完成时通知您;
这是输出
你可以使用这个插件timer_builder
timer_builder 根据预定、定期或动态生成的时间事件自行重建的小部件。
例子
定期重建
import 'package:timer_builder/timer_builder.dart';
class ClockWidget extends StatelessWidget {
@override
Widget build(BuildContext context) {
return TimerBuilder.periodic(Duration(seconds: 1),
builder: (context) {
return Text("${DateTime.now()}");
}
);
}
}
按计划重建
import 'package:timer_builder/timer_builder.dart';
class StatusIndicator extends StatelessWidget {
final DateTime startTime;
final DateTime endTime;
StatusIndicator(this.startTime, this.endTime);
@override
Widget build(BuildContext context) {
return TimerBuilder.scheduled([startTime, endTime],
builder: (context) {
final now = DateTime.now();
final started = now.compareTo(startTime) >= 0;
final ended = now.compareTo(endTime) >= 0;
return Text(started ? ended ? "Ended": "Started": "Not Started");
}
);
}
}
已经提供了很多答案。我建议一个捷径-
使用这个包Custom_timer
将此添加到您的包的 pubspec.yaml 文件中:
dependencies:
custom_timer: ^0.0.3
(使用最新版本)
而且实施起来非常简单
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Scaffold(
appBar: AppBar(
title: Text("CustomTimer example"),
),
body: Center(
child: CustomTimer(
from: Duration(hours: 12),
to: Duration(hours: 0),
onBuildAction: CustomTimerAction.auto_start,
builder: (CustomTimerRemainingTime remaining) {
return Text(
"${remaining.hours}:${remaining.minutes}:${remaining.seconds}",
style: TextStyle(fontSize: 30.0),
);
},
),
),
),
);
}
import 'dart:async';
import 'package:flutter/material.dart';
class CustomTimer extends StatefulWidget {
@override
_CustomTimerState createState() => _CustomTimerState();
}
class _CustomTimerState extends State<CustomTimer> {
final _maxSeconds = 61;
int _currentSecond = 0;
Timer _timer;
String get _timerText {
final secondsPerMinute = 60;
final secondsLeft = _maxSeconds - _currentSecond;
final formattedMinutesLeft =
(secondsLeft ~/ secondsPerMinute).toString().padLeft(2, '0');
final formattedSecondsLeft =
(secondsLeft % secondsPerMinute).toString().padLeft(2, '0');
print('$formattedMinutesLeft : $formattedSecondsLeft');
return '$formattedMinutesLeft : $formattedSecondsLeft';
}
@override
void initState() {
super.initState();
_startTimer();
}
@override
void dispose() {
_timer.cancel();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Icon(Icons.timer),
Text(_timerText),
],
),
),
);
}
void _startTimer() {
final duration = Duration(seconds: 1);
_timer = Timer.periodic(duration, (Timer timer) {
setState(() {
_currentSecond = timer.tick;
if (timer.tick >= _maxSeconds) timer.cancel();
});
});
}
}
要以这种格式 hh:mm:ss 显示您的总秒数,您可以使用以下方法:
String getDuration(int totalSeconds) {
String seconds = (totalSeconds % 60).toInt().toString().padLeft(2, '0');
String minutes =
((totalSeconds / 60) % 60).toInt().toString().padLeft(2, '0');
String hours = (totalSeconds ~/ 3600).toString().padLeft(2, '0');
return "$hours\:$minutes\:$seconds";
}
我已经创建了一个没有任何插件的神奇计时器,在这里您还可以获得倒数计时器。 并且不要忘记在按下后退时停止计时器。
这是我的计时器完整项目的 link。 *Hope this will help someone. Thank you. *
import 'dart:async';
import 'package:flutter/material.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(
primarySwatch: Colors.blue,
),
home: AttendanceScreen(),
);
}
}
class AttendanceScreen extends StatefulWidget {
AttendanceScreen();
@override
_AttendanceScreenState createState() => _AttendanceScreenState();
}
class _AttendanceScreenState extends State<AttendanceScreen> {
static var countdownDuration = Duration(minutes: 10);
static var countdownDuration1 = Duration(minutes: 10);
Duration duration = Duration();
Duration duration1 = Duration();
Timer? timer;
Timer? timer1;
bool countDown = true;
bool countDown1 = true;
@override
void initState() {
var hours;
var mints;
var secs;
hours = int.parse("00");
mints = int.parse("00");
secs = int.parse("00");
countdownDuration = Duration(hours: hours, minutes: mints, seconds: secs);
startTimer();
reset();
var hours1;
var mints1;
var secs1;
hours1 = int.parse("10");
mints1 = int.parse("00");
secs1 = int.parse("00");
countdownDuration1 =
Duration(hours: hours1, minutes: mints1, seconds: secs1);
startTimer1();
reset1();
super.initState();
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onWillPop,
child: Scaffold(
appBar: AppBar(
title: Text("Timer Example"),
leading: IconButton(
icon: Icon(Icons.arrow_back_ios),
color: Colors.white,
onPressed: () {
_onWillPop();
},
),
),
body: Container(
color: Colors.black12,
width: double.infinity,
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
SizedBox(
height: 20,
),
Text(
"Timer",
style: TextStyle(fontSize: 25),
),
Container(
margin: EdgeInsets.only(top: 30, bottom: 30),
child: buildTime()),
SizedBox(
height: 20,
),
Text(
"Count down timer",
style: TextStyle(fontSize: 25),
),
Container(
margin: EdgeInsets.only(top: 30, bottom: 30),
child: buildTime1()),
]),
),
),
);
}
Future<bool> _onWillPop() async {
final isRunning = timer == null ? false : timer!.isActive;
if (isRunning) {
timer!.cancel();
}
Navigator.of(context, rootNavigator: true).pop(context);
return true;
}
void reset() {
if (countDown) {
setState(() => duration = countdownDuration);
} else {
setState(() => duration = Duration());
}
}
void reset1() {
if (countDown) {
setState(() => duration1 = countdownDuration1);
} else {
setState(() => duration1 = Duration());
}
}
void startTimer() {
timer = Timer.periodic(Duration(seconds: 1), (_) => addTime());
}
void startTimer1() {
timer = Timer.periodic(Duration(seconds: 1), (_) => addTime1());
}
void addTime() {
final addSeconds = 1;
setState(() {
final seconds = duration.inSeconds + addSeconds;
if (seconds < 0) {
timer?.cancel();
} else {
duration = Duration(seconds: seconds);
}
});
}
void addTime1() {
final addSeconds = 1;
setState(() {
final seconds = duration1.inSeconds - addSeconds;
if (seconds < 0) {
timer1?.cancel();
} else {
duration1 = Duration(seconds: seconds);
}
});
}
Widget buildTime() {
String twoDigits(int n) => n.toString().padLeft(2, '0');
final hours = twoDigits(duration.inHours);
final minutes = twoDigits(duration.inMinutes.remainder(60));
final seconds = twoDigits(duration.inSeconds.remainder(60));
return Row(mainAxisAlignment: MainAxisAlignment.center, children: [
buildTimeCard(time: hours, header: 'HOURS'),
SizedBox(
width: 8,
),
buildTimeCard(time: minutes, header: 'MINUTES'),
SizedBox(
width: 8,
),
buildTimeCard(time: seconds, header: 'SECONDS'),
]);
}
Widget buildTime1() {
String twoDigits(int n) => n.toString().padLeft(2, '0');
final hours = twoDigits(duration1.inHours);
final minutes = twoDigits(duration1.inMinutes.remainder(60));
final seconds = twoDigits(duration1.inSeconds.remainder(60));
return Row(mainAxisAlignment: MainAxisAlignment.center, children: [
buildTimeCard(time: hours, header: 'HOURS'),
SizedBox(
width: 8,
),
buildTimeCard(time: minutes, header: 'MINUTES'),
SizedBox(
width: 8,
),
buildTimeCard(time: seconds, header: 'SECONDS'),
]);
}
Widget buildTimeCard({required String time, required String header}) =>
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
padding: EdgeInsets.all(8),
decoration: BoxDecoration(
color: Colors.white, borderRadius: BorderRadius.circular(20)),
child: Text(
time,
style: TextStyle(
fontWeight: FontWeight.bold,
color: Colors.black,
fontSize: 50),
),
),
SizedBox(
height: 24,
),
Text(header, style: TextStyle(color: Colors.black45)),
],
);
}
import 'package:rxdart/rxdart.dart';
final BehaviorSubject<int> resendTimeController = BehaviorSubject<int>();
static const timerDuration = 90;
int resendTimer = 0;
Timer? timer;
void startTimer() {
timer?.cancel();
resendTimer = timerDuration;
timer = Timer.periodic(const Duration(seconds: 1), (timer) {
if (resendTimer > 0) {
resendTimer--;
resendTimeController.add(resendTimer);
if (resendTimer == 0) {
timer.cancel();
}
}
});
}
and use intl this
StreamBuilder<int>(
stream: _bloc.resendTimeController,
builder: (context, snapshot) {
if (!snapshot.hasData) {
return Container();
}
final DateTime date = DateTime.fromMillisecondsSinceEpoch(snapshot.data! * 1000);
return GestureDetector(
onTap: () {
if (snapshot.data == 0) {
_bloc.resendCode();
}
},
child: Text(
snapshot.data! > 0 ? 'Resend code ${DateFormat('mm:ss').format(date)}' : 'Resend SMS',
),
);
},
),
import 'package:async/async.dart';
late CancelableOperation? cancellableOperation;
int counter = 5;
StatefulBuilder(
builder: (context, setState) {
if (counter > 0) {
cancellableOperation = CancelableOperation.fromFuture(
Future.delayed(const Duration(seconds: 1)),
onCancel: () => {},
);
cancellableOperation?.value.whenComplete(() => setState(() => counter--));
return buildButton(
text: 'Wait($counter)',
textColor: getTextColor,
backgroundColor: Colors.grey.withOpacity(0.5),
onPressed: () {},
);
}
return buildButton(
text: 'Complete',
textColor: Colors.green,
backgroundColor: Colors.greenAccent.withOpacity(0.5),
onPressed: () {},
);
},
)
我为对话框的完成按钮做了类似的事情。在显示完成按钮之前,它计数 5 秒。但如果您在计数完成前关闭对话框或页面,请不要忘记调用 cancellableOperation?.cancel()
。