How to convert the time to minutes of Timer - flutter

Question

I have this time that starts when a product is initialized and I want to format it to 00:00 instead of just 0.
Timer _timer;
_startTimer(prod) {
prod.tempo = 0;
_timer = Timer.periodic(Duration(seconds: 1), (timer) {
setState(() {
prod.tempo++;
});
});
}`
[you can se the time in red I want to convert][1]
[1]: https://i.stack.imgur.com/vCv7p.jpg

Answer 1

If you have a total number of seconds, you can pretty print it with:
String toTimeField(int n) => n.toString().padLeft(2, '0');
var seconds = totalSeconds % 60;
var minutes = totalSeconds ~/ 60;
var prettyDuration = '${toTimeField(minutes)}:${toTimeField(seconds)}`;
That said, if you want to measure a duration, you're usually better off keeping track of the starting time and then computing the difference with the current time. That prevents accumulating error if there are any timing discrepancies from when your callback fires. You can use DateTime.now() to get the current time, store it, and then when your callback fires, call DateTime.now() again and subtract the original value. Or use the Stopwatch class, which does that for you. Using Stopwatch and Duration, you'd do:
_startTimer(prod) {
prod.stopwatch = Stopwatch();
...
}
...
final elapsed = prod.stopwatch.elapsed;
var seconds = elapsed.inSeconds % 60;
var minutes = elapsed.inMinutes;
Finally, I also recommend avoiding using : when printing durations since it could easily be misinterpreted. Does 12:34 represent a time? Does it represent 12 hours and 34 minutes or 12 minutes and 34 seconds? Printing durations as 12m34s is much clearer.

Answer 2

You can format the String as follows:
var seconds = prod.tempo % 60;
var minutes = (prod.tempo - seconds) / 60;
//if you have less than 10 seconds/minutes, prepend a '0':
String secondsAsString = seconds < 10 ? '0$seconds' : seconds;
String minutesAsString = minutes < 10 ? '0$minutes' : minutes;
String displayTime = 'Tempo: ' + secondsAsString + ':' + minutesAsString;