嗨，我有一个带有倒计时计时器的颤动应用程序，我从这部视频https://www.youtube.com/watch?v=Rkkb8P9LsPw&list=PL26uY6-lIzqmfQO2iK5vTpmp5Iz_rHyr6&index=13中获得了它的效果，但是工作正常，但是当它计数时，它会导致小部件每秒重建一次，因此它会初始化为init状态，所以我不这样做不知道如何停止不必要的重建，只在显示计时器的地方重建，这将是自定义计时器代码
class TimeLeft {
List<String> timeLeft(DateTime due) {
List<String> retVal = List(2);
Duration _timeUntilDue = due.difference(DateTime.now());
//int _monthsUntil;
int _daysUntil = _timeUntilDue.inDays;
int _hoursUntil = _timeUntilDue.inHours - (_daysUntil * 24);
int _minUntil =
_timeUntilDue.inMinutes - (_daysUntil * 24 * 60) - (_hoursUntil * 60);
int _secUntil = _timeUntilDue.inSeconds -
(_daysUntil * 24 * 60 * 60) -
(_hoursUntil * 60 * 60) -
(_minUntil * 60);
if (_daysUntil > 0) {
retVal[0] =
//_daysUntil > 30 ? '${double.parse('${_daysUntil/30}').toStringAsFixed(0)}' + ' month ' : '' +
_daysUntil.toString() +
" day" +
'${_daysUntil > 1 ? 's' : ''}' +
' : ' +
_hoursUntil.toString() +
" hours : " +
_minUntil.toString() +
" mins : " +
_secUntil.toString() +
' sec';
} else if (_hoursUntil > 0) {
retVal[0] = _hoursUntil.toString() +
" hours : " +
_minUntil.toString() +
"mins : " +
_secUntil.toString() +
'sec';
} else if (_minUntil > 0) {
retVal[0] =
_minUntil.toString() + " mins : " + _secUntil.toString() + 'sec';
} else if (_secUntil > 0) {
retVal[0] = _secUntil.toString() + ' : sec';
} else {
retVal[0] = 'Done';
}
Duration _timeUntilReveal =
due.add(Duration(hours: 1)).difference(DateTime.now());
int _daysUntilReveal = _timeUntilReveal.inDays;
int _hoursUntilReveal = _timeUntilReveal.inHours - (_daysUntilReveal * 24);
int _minUntilReveal = _timeUntilReveal.inMinutes -
(_daysUntilReveal * 24 * 60) -
(_hoursUntilReveal * 60);
int _secUntilReveal = _timeUntilReveal.inSeconds -
(_daysUntilReveal * 24 * 60 * 60) -
(_hoursUntilReveal * 60 * 60) -
(_minUntilReveal * 60);
if (_daysUntilReveal > 0) {
retVal[1] = _daysUntilReveal.toString() +
" day" +
'${_daysUntilReveal > 1 ? 's' : ''}';
//_hoursUntilReveal.toString() +" hours";
//_minUntilReveal.toString() +" mins" ;
//_secUntilReveal.toString() +': sec';
} else if (_hoursUntilReveal > 0) {
retVal[1] = _hoursUntilReveal.toString() +
" hours : " +
_minUntilReveal.toString() +
"mins ";
//_secUntilReveal.toString() +'sec';
} else if (_minUntilReveal > 0) {
retVal[1] = _minUntilReveal.toString() +
" mins : " +
_secUntilReveal.toString() +
'sec';
} else if (_secUntilReveal > 0) {
retVal[1] = _secUntilReveal.toString() + ' : sec';
} else {
retVal[1] = "Done";
}
return retVal;
}
}
这是我使用它的页面
class _InProgressPageState extends State<InProgressPage> {
Timer _timer;
var value;
List<String> _timeUntil = List(2);
void _startTimer(DateTime time) {
_timer = Timer.periodic(Duration(seconds: 1), (timer) {
if (this.mounted)
return setState(() {
_timeUntil =
TimeLeft().timeLeft(DateTime.parse("2020-10-01 00:00:00Z"));
});
});
}
@override
void initState() {
_startTimer(DateTime.now());
super.initState();
}
@override
void dispose() {
_timer.cancel();
super.dispose();
}
@override
Widget build(BuildContext context) {
print('Build InProgress');
ThemeManagment themeManagment = Provider.of<ThemeManagment>(context);
DataNotifier dataNotifier = Provider.of<DataNotifier>(context,listen: false);
double size = MediaQuery.of(context).size.height;
return Scaffold(
backgroundColor: themeManagment.theme == ThemeType.Dark
? Color(0xFF161A26)
: Colors.white
.withOpacity(0.15),
body: dataNotifier.dataList.length == 0
? Center(
child: Text(
'You Have No Inprogress Data',
style: GoogleFonts.lato(
color: themeManagment.theme == ThemeType.Dark
? Colors.white
: Color(0xFF161A26),
fontSize: 15,
),
),
)
: Padding(
padding: const EdgeInsets.only(top: 8.0, bottom: 1),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Expanded(
child: ListView.builder(
itemCount: dataNotifier.dataList.length,
itemBuilder: (context, int i) => Padding(
padding: const EdgeInsets.only(
bottom: 10, right: 10, left: 10, top: 5),
child: Material(
borderRadius: BorderRadius.circular(20),
elevation: 10,
color: Colors.transparent,
//shadowColor: Colors.lightBlueAccent,
child: Container(
decoration: BoxDecoration(
color: themeManagment.theme ==
ThemeType.Dark
? Color(0xFF161A26)
:Colors.white.withOpacity(
0.85),
borderRadius: BorderRadius.circular(20),
border: Border.all(
width: 1,
color: themeManagment.theme ==
ThemeType.Dark
? Colors.grey.withOpacity(0.1)
: Colors.blueGrey.withOpacity(0.2),
),
),
child: Padding(
padding: const EdgeInsets.all(10),
child: Column(
mainAxisAlignment:
MainAxisAlignment.spaceEvenly,
children: [
Column(
children: [
Padding(
padding:
const EdgeInsets.all(8.0),
child: Text(
'Time Left To Join',
style: GoogleFonts.lato(
fontSize: size / 54,
color:
themeManagment.theme ==
ThemeType.Dark
? Colors.white
: Color(0xFF161A26),
),
),
),
Text(
_timeUntil[0] ?? 'loading...',
style: GoogleFonts.lato(
color: Color(
0xFF18DEBA), //Color(0xFFFF9A44),
fontSize: size / 40,
),
),
],
),