Android Chronometer resume function

Question

I mm trying to create a resume button in my Android app using Chronometer. So far I have this code snippet for the resume method:

private long pauseResume() {

    long timeWhenStopped = chronometer.getBase() - SystemClock.elapsedRealtime();

    return timeWhenStopped;

}

And here's the code for the resume button:

 public void onClick(View v) {
      switch(v.getId()) {

          ...

          case R.id.resume_button:                
              chronometer.setBase(SystemClock.elapsedRealtime() + pauseResume());
              chronometer.start();    
              break;

      }
}

THE PROBLEM: Example, when I pause the timer at 00:05 and then I press the resume button 10 seconds later, the timer will resume counting at 00:15.

I want it to start at 00:05 again, not 00:15, because as it is a "resume" function.

I am very glad you could help. Thanks.

Answer 1

A little bit too late but it might help others. I think this is the solution to your problem.

Start / Resume chronometer:

private void chronoStart()
{
    // on first start
    if ( mLastStopTime == 0 )
        mChronometer.setBase( SystemClock.elapsedRealtime() );
    // on resume after pause
    else
    {
        long intervalOnPause = (SystemClock.elapsedRealtime() - mLastStopTime);
        mChronometer.setBase( mChronometer.getBase() + intervalOnPause );
    }

    mChronometer.start();
}

Pause chronometer:

private void chronoPause()
{
    mChronometer.stop();

    mLastStopTime = SystemClock.elapsedRealtime();
}

You need to remember last chronometer stop time.

On resume, you calculate how long it took between the last stop time and the new start time. When you have this interval you just add the interval to your chronometer base time (you "move" original start time).

Hope this helps ;)

Answer 2

Chronometer has used for implements a simple timer.You can give it a start time in the elapsedRealtime() timebase, and it counts up from that, or if you don't give it a base time, it will use the time at which you call start().

long timeWhenStopped = 0;

Update the value of the variable when you stop the chronometer like this:

timeWhenStopped = mChronometer.getBase() - SystemClock.elapsedRealtime();
mChronometer.stop();

We will also use this variable to adjust the chronometer before starting it:

mChronometer.setBase(SystemClock.elapsedRealtime() + timeWhenStopped);
mChronometer.start();

And finally if you have a way to reset your chronometer then you should remember to also reset the timeWhenStopped variable. Something like this:

mChronometer.setBase(SystemClock.elapsedRealtime());
timeWhenStopped = 0;

Answer 3

here's a kotlin version:

private var chronometerPausedTime: Long = 0

// to start the chronometer with 00:00
private fun Chronometer.startFromZero() {
    base = SystemClock.elapsedRealtime()
    start()
}

private fun Chronometer.pause() {
    chronometerPausedTime = SystemClock.elapsedRealtime() - this.base
    stop()
}

private fun Chronometer.resume() {
    base = SystemClock.elapsedRealtime() - chronometerPausedTime
    chronometerPausedTime = 0
    start()
}

to use:

binding.chronometer.startFromZero()

//pause
binding.chronometer.pause()

//resume
binding.chronometer.resume()