倒计时到日期时间，停止一段时间并在一段时间后再次计数

Question

在周四、周五、周六、周日下午 6 点至晚上 10 点，应用允许用户某些权限。

我想显示从任何日期到每个星期四至星期日（下午 6 点至晚上 10 点）这段时间的倒计时

例如，如果是星期一，计时器将倒计时到星期四下午 6 点。如果是星期五早上 8 点，则倒计时到星期五下午 6 点。在任何时候，计时器都应该显示一次计时。

如果在周四至周日（下午 6 点至晚上 10 点）内，计时器将消失。仅在周四至周日再次出现 22:00:01。

我该如何实现？此外，对于日期列表，是否有一种方法可以确保每个星期四 - 星期日（下午 6 点）倒计时，而不是像看到的那样对日期进行硬编码。没有使用包。我被困在下面的代码中。

以下是我截断的代码：

List<DateTime> date =
[DateTime.parse("2021-08-26 18:00:00Z"),
DateTime.parse("2021-08-27 18:00:00Z"),
DateTime.parse("2021-08-28 18:00:00Z"),
DateTime.parse("2021-08-29 18:00:00Z"),];

@override 
Widget build(BuildContext context){
return Scaffold(
body: Center(child: ListView.builder(
itemCount: date.length,
itemBuilder: (context, index){
countTime = CountDown().timeLeft(date[0], 'Completed');
return Text(
countTime, 
style(TextStyle(fontSize:25.0));
...

感谢您的帮助。

编辑如下：

编辑以显示倒计时中增加的天数小部件错误。

remainingTimeToText 上的代码被截断

 String remainingTimeToText(Duration duration) {
    DateTime now = DateTime.now();
    int days = duration.inDays;
    int hours = duration.inHours - days * 24;
    int minutes = duration.inMinutes - hours * 60;
    int seconds = duration.inSeconds - hours * 3600 - minutes * 60;
    if (now.weekday < 4) {
      return days.toString() +
          ' days ' +
          hours.toString() +
          ":" +
          minutes.toString() +
          ":" +
          seconds.toString();
    } else if (now.weekday>3){return 
        hours.toString() +
        ":" +
        minutes.toString() +
        ":" +
        seconds.toString();
  }

Answer 1

import 'package:flutter/material.dart';

//needed for using the Timer
import 'dart:async';

class TimerScreen extends StatefulWidget {
  const TimerScreen({Key? key}) : super(key: key);

  @override
  _TimerScreenState createState() => _TimerScreenState();
}

class _TimerScreenState extends State<TimerScreen> {
//the time left till the next special time comes up
  String timeLeft = "";

  ///takes an int when converting it to string adds
  /// a 0 in fron when it is smaller than 10
  ///
  ///will look nicer  when displayed on the screen
  String customString(int i) {
    if (i < 10) {
      return "0" + i.toString();
    } else {
      return i.toString();
    }
  }

  ///converts a duration to a
  ///string: days hours:minuts:seconds
  String remainingTimeToText(Duration duration) {
    print(duration);
    int days = duration.inDays;
    int hours = duration.inHours - days * 24;
    int minutes = duration.inMinutes - hours * 60 - days * 24 * 60;
    int seconds =
        duration.inSeconds - hours * 3600 - minutes * 60 - days * 86400;
    if (days > 0) {
      String s = " days ";
      if (days == 1) {
        s = " day ";
      }
      return days.toString() +
          s +
          customString(hours) +
          ":" +
          customString(minutes) +
          ":" +
          customString(seconds);
    } else {
      return customString(hours) +
          ":" +
          customString(minutes) +
          ":" +
          customString(seconds);
    }
  }

  ///given a list of ints and another int value
  ///
  ///returs true it the value is contained in the list
  ///
  ///else returns false
  bool listContainsValue(List<int> list, int value) {
    for (var element in list) {
      if (element == value) {
        print(true);
        return true;
      }
    }
    print(false);
    return false;
  }

  ///returns the time remaining till the next
  ///special time takes place as a string: hours:minutes:seconds
  ///
  ///if specialTime is currently active
  ///it returns an empty string
  ///
  ///specialTimes have to be given by entering an int list with all special
  ///weekdays and entering the startingHour and the endingHour
  timeRemaining(List<int> weekdays, int startingHour, int endingHour) {
    DateTime now = DateTime.now();
    bool timeIsSpecial = false;
    for (var specificWeekday in weekdays) {
      if (now.weekday == specificWeekday &&
          (now.hour >= startingHour && now.hour < endingHour)) {
        timeIsSpecial = true;
      }
    }
    print(timeIsSpecial);
    if (!timeIsSpecial) {
      DateTime nextSpecialTime =
          DateTime(now.year, now.month, now.day, startingHour);
      while (nextSpecialTime.isBefore(now) ||
          !listContainsValue(weekdays, nextSpecialTime.weekday)) {
        nextSpecialTime = nextSpecialTime.add(Duration(days: 1));
      }
      return remainingTimeToText(nextSpecialTime.difference(now));
    } else {
      return "";
    }
  }

  @override
  void initState() {
    Timer.periodic(Duration(seconds: 1), (timer) {
      if (mounted == true) {
        setState(() {
          timeLeft = timeRemaining([4, 5, 6], 18, 22);
        });
      }
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: Container(
        child: Center(
          child: Text(
            timeLeft,
            style: TextStyle(
              color: Colors.black,
              fontSize: 40,
            ),
          ),
        ),
      ),
    );
  }
}

倒计时到日期时间，停止一段时间并在一段时间后再次计数

Countdown to datetime, stop for a period and after period, count again

datetime

timer

countdown

flutter