This is my first pull request and contribution to a public repository. I'm also pretty new on Flutter. I added a bool variable in order to avoid the disposing of the controller when it's passed by parameter. Fixing in this way the issue #14

Hi, thank you for the awesome Timer, it's really customizable, but I have one issue. According to the code, these builders will fire only when controller is provided. Why?

I am trying to set up a countdown timer but it keeps throwing an error. Controller is already disposed here's my code

CustomTimer(
    controller: controller,
    begin: Duration(seconds: 30),
    end: Duration(seconds: 0),
    onChangeState: (s) {
      if(s == CustomTimerState.finished) {
        print("We completed finished");
        // Prevent calling setState during a widget build
        showTimer.value = false;
        controller.reset();
      }
    },
    builder: (remaining) {
      return Text("${remaining.minutes}:${remaining.seconds}", style: TextStyle(
        fontFamily: "Montserrat",
        fontWeight: FontWeight.w600,
        color: primaryColor,
        fontSize: 14,
      ));
    },
  ),

I was expecting the behaviour of onFinish to be triggered when it gets to Duration(seconds: 0) yet it didn't and it continued to negative values, is this a bug? thanks!

 Widget _timer() {
    return CustomTimer(
      controller: _timerController,
      from: widget.durationLeft,
      to: Duration(seconds: 0),
      interval: Duration(seconds: 1),
      onFinish: () => widget.onFinish(),
      onBuildAction: CustomTimerAction.auto_start,
      builder: (CustomTimerRemainingTime remaining) {
        return Text('${remaining.hours}:${remaining.minutes}:${remaining.seconds}');
      },
    );
  }

I need a custom duration: eventDate.difference(DateTime.now()) for the from Yet the onFinished wasn't being triggered so I tried to add microseconds to the from property and indeed it doesn't trigger it and continue to countdown below 0

	from: Duration(seconds: 10, microseconds: 11111),

CustomTimer(
  from: Duration(seconds: 10, microseconds: 11111),
  to: Duration(hours: 0),
  onBuildAction: CustomTimerAction.auto_start,
  onFinish: () => _refreshData(),
  builder: (CustomTimerRemainingTime remaining) {
    return Text(
      '${remaining.hours}:${remaining.minutes}:${remaining.seconds}')
    );
  },
)

A workaround that works is convert to seconds and convert to Duration

from: Duration(seconds: Duration(seconds: 10, microseconds: 11111).inSeconds),

on version 0.0.3 this worked fine but since I upgraded to 0.0.5 the counter goes down to negative values

CustomTimer(
      controller: _controller,
      from: Duration(seconds: 0),
      to: Duration(hours: 10),
      interval: Duration(milliseconds: 500),
      onBuildAction: CustomTimerAction.auto_start,
      builder: (CustomTimerRemainingTime remaining) {
        return Text(
          '${remaining.minutes}:${remaining.seconds}',
          style: _tema.title2().copyWith(color: _tema.backgroundTertiary()),
        );
      },
    )

Hi, previously I used "onBuildAction: CustomTimerAction.auto_start", but now it's gone, and the timer doesn't auto start. How to auto start on build without using the external controller?

CustomTimer( from: Duration(milliseconds: 0), to: Duration(hours: 1), onBuildAction: CustomTimerAction.auto_start, builder: (CustomTimerRemainingTime remaining) { return Text( "${remaining.minutes}:${remaining.seconds}:${remaining.milliseconds} ", style: TextStyle(fontSize: 20.0), ); }, ),

https://user-images.githubusercontent.com/34600049/128942222-1531381f-2b6e-491e-b1e6-0e3bb7c07b93.mov

I want to use the same time accessed between multiple screens, The timer is resetting in every screen currently, even when I use the same controller.

And when I come back to the previous screen, two instances of the timer running.

I want one instance of the timer used across multiple screens, do we have an option for that?

Love this package, nice and simple & thank you for producing it. Now, I think something important could be improved.

I'm no Flutter pro engineer, mega computer genius, crazy Stephen Hawking intellectual, but rebuilding a widget a million times per second has always since I started learning Flutter been a serious main issue, concern & my arch nemesis and looks like Flutter's also. However it is also necessary IF one is showing milliseconds as part of their timer. I can understand this aspect of the programming. This uses enormous system resources in debug mode.

So my proposal is to include some sort of boolean value updateForMilliseconds or something which uses state and does not rebuild so much when not necessary when not using milliseconds value from timer. If using milliseconds then use the good old stateful widget and rebuild it quickly so user can see milliseconds passing.

I suppose all timers would have this issue and this is why I think this could be very valuable when some don't need rapid updates.

Showing my performance issue

class OTPTimer extends StatelessWidget {
  final CustomTimerController timeController;

  const OTPTimer({
    required this.timeController,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return CustomTimer(
        controller: timeController,
        begin: const Duration(minutes: 10),
        end: const Duration(minutes: 0),
        builder: (timeRemaining) {
          return Text(
            "${timeRemaining.hours}:${timeRemaining.minutes}:${timeRemaining.seconds}",
            style: timerStyle(timeRemaining),
          );
        });
  }

  // // Timer time text
  TextStyle timerStyle(CustomTimerRemainingTime timeRemaining) {
    print(int.parse(timeRemaining.secondsWithoutFill));                          // Prints 40-60 times per second (useless in my case)
    // Green indicator text
    if (int.parse(timeRemaining.minutesWithoutFill) > 3) {
      return ThemeEndpoints.infoHeaderPositive();
    }
    // Yellow indicator warning text
    if (int.parse(timeRemaining.minutesWithoutFill) < 3 &&
        int.parse(timeRemaining.minutesWithoutFill) > 1) {
      return ThemeEndpoints.infoHeaderWarning();
    }
    // Red indicator warning text
    return ThemeEndpoints.infoHeaderNegative();
  }

When the counter reaches the end its still in CustomTimerState.counting. I would like to take action and update certain state values once the clock hits 00:00:00. What would be the best way to do that please?

It would be nice to be have the controller be able to keep track of the timer regardless of whether or not the timer is in view or not.

I envision the controller being the source of truth for the timer widget and the widget simply latches on to the current state of the controller it was initialized with whenever it comes into view. This way we can get and set the timer from just the controller in other parts of an app.

The initial discussions for this issue can be found here.