timed_builder 2.0.0

A widget that rebuilds itself on scheduled, periodic, or dynamically generated time events.

example/lib/example.dart

import 'package:flutter/material.dart';
import 'package:timed_builder/timed_builder.dart';

void main() {
  runApp(SampleApp());
}

class SampleApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return SampleAppState();
  }
}

class SampleAppState extends State<SampleApp> {
  late DateTime alert;

  @override
  void initState() {
    super.initState();
    alert = DateTime.now().add(Duration(seconds: 10));
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Sample App'),
        ),
        body: TimedBuilder.scheduled([alert], builder: (context) {
          // This function will be called once the alert time is reached
          var now = DateTime.now();
          var reached = now.compareTo(alert) >= 0;
          final textStyle = Theme.of(context).textTheme.headline6;
          return Center(
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: <Widget>[
                Icon(
                  reached ? Icons.alarm_on : Icons.alarm,
                  color: reached ? Colors.red : Colors.green,
                  size: 48,
                ),
                !reached
                    ? TimedBuilder.periodic(Duration(seconds: 1),
                        alignment: Duration.zero, builder: (context) {
                        // This function will be called every second until the alert time
                        var now = DateTime.now();
                        var remaining = alert.difference(now);
                        return Text(
                          formatDuration(remaining),
                          style: textStyle,
                        );
                      })
                    : Text("Alert", style: textStyle),
                ElevatedButton(
                  child: Text("Reset"),
                  onPressed: () {
                    setState(() {
                      alert = DateTime.now().add(Duration(seconds: 10));
                    });
                  },
                ),
              ],
            ),
          );
        }),
      ),
      theme: ThemeData(backgroundColor: Colors.white),
    );
  }
}

String formatDuration(Duration d) {
  String f(int n) {
    return n.toString().padLeft(2, '0');
  }

  // We want to round up the remaining time to the nearest second
  d += Duration(microseconds: 999999);
  return "${f(d.inMinutes)}:${f(d.inSeconds % 60)}";
}