jumpTo method
Function to move the current time.
Implementation
void jumpTo(Duration duration) {
final isCountUp = begin < end;
final a = isCountUp ? begin.inMilliseconds : end.inMilliseconds;
final b = isCountUp ? end.inMilliseconds : begin.inMilliseconds;
final value = (duration.inMilliseconds - a) / (b - a);
final next = isCountUp ? value : 1.0 - value;
if (next <= 0.0 && state.value != CustomTimerState.counting) return reset();
if (next >= 1.0) return finish();
_animationController.value = next;
if (state.value == CustomTimerState.counting)
start();
else
_pause();
}