Seconds CountDown Timer

Question

I have a lblCountdown with an int value of 60. I want to make the int value of the lblCountDown decrease with seconds until it reaches 0.

This is what I have so far:

Answer 1

.

Usage:

CountDownTimer timer = new CountDownTimer();


//set to 30 mins
timer.SetTime(30,0);     

timer.Start();

//update label text
timer.TimeChanged += () => Label1.Text = timer.TimeLeftMsStr; 

// show messageBox on timer = 00:00.000
timer.CountDownFinished += () => MessageBox.Show("Timer finished the work!"); 

//timer step. By default is 1 second
timer.StepMs = 77; // for nice milliseconds time switch

and don't forget to Dispose(); when timer is useless for you;

Source code:

using System;
using System.Diagnostics;
using System.Windows.Forms;

public class CountDownTimer : IDisposable
{
    public Stopwatch _stpWatch = new Stopwatch();

    public Action TimeChanged;
    public Action CountDownFinished;

    public bool IsRunnign => timer.Enabled;

    public int StepMs
    {
        get => timer.Interval;
        set => timer.Interval = value;
    }

    private Timer timer = new Timer();

    private TimeSpan _max = TimeSpan.FromMilliseconds(30000);

    public TimeSpan TimeLeft => (_max.TotalMilliseconds - _stpWatch.ElapsedMilliseconds) > 0 ? TimeSpan.FromMilliseconds(_max.TotalMilliseconds - _stpWatch.ElapsedMilliseconds) : TimeSpan.FromMilliseconds(0);

    private bool _mustStop => (_max.TotalMilliseconds - _stpWatch.ElapsedMilliseconds) < 0;

    public string TimeLeftStr => TimeLeft.ToString(@"\mm\:ss");

    public string TimeLeftMsStr => TimeLeft.ToString(@"mm\:ss\.fff");

    private void TimerTick(object sender, EventArgs e)
    {
        TimeChanged?.Invoke();

        if (_mustStop)
        {
            CountDownFinished?.Invoke();
            _stpWatch.Stop();
            timer.Enabled = false;
        }
    }

    public CountDownTimer(int min, int sec)
    {
        SetTime(min, sec);
        Init();
    }

    public CountDownTimer(TimeSpan ts)
    {
        SetTime(ts);
        Init();
    }

    public CountDownTimer()
    {
        Init();
    }

    private void Init()
    {
        StepMs = 1000;
        timer.Tick += new EventHandler(TimerTick);
    }

    public void SetTime(TimeSpan ts)
    {
        _max = ts;
        TimeChanged?.Invoke();
    }

    public void SetTime(int min, int sec = 0) => SetTime(TimeSpan.FromSeconds(min * 60 + sec));

    public void Start() {
        timer.Start();
        _stpWatch.Start();
    }

    public void Pause()
    {
        timer.Stop();
        _stpWatch.Stop();
    }

    public void Stop()
    {
        Reset();
        Pause();
    }

    public void Reset()
    {
        _stpWatch.Reset();
    }

    public void Restart()
    {
        _stpWatch.Reset();
        timer.Start();
    }

    public void Dispose() => timer.Dispose();
}

(updated 6.6.2020, because of problems with time calculation)