tick method

bool tick(double now)

Advances everything to now (in seconds; the same clock as touch times). Returns whether anything is still moving.

Implementation

bool tick(double now) {
  if (!_started) {
    _started = true;
    _now = now;
  }
  final double elapsed = math.max(now - _now, 0.0);
  double start =
      now - (_idle ? math.min(elapsed, _firstStep) : math.min(elapsed, 0.1));
  // Touch times: ignore any on another clock; a resting bar starts from
  // the earliest touch.
  double? timeOf(_TouchEvent e) {
    final double? t = e.time;
    return t == null || t < now - 0.1 || t > now + 0.05 ? null : t;
  }

  if (_idle) {
    for (final _TouchEvent e in _pending) {
      final double? t = timeOf(e);
      if (t != null) {
        start = math.min(start, math.max(t, now - 0.05));
      }
    }
  }
  var t = start;
  for (final _TouchEvent e in _pending) {
    final double te = (timeOf(e) ?? (start + now) / 2).clamp(t, now);
    _advance(t, te);
    _apply(e, te);
    t = te;
  }
  _pending.clear();
  _advance(t, now);
  _now = now;

  // The finger's speed along the bar, from where the lens belonged over
  // the last 50ms of frames: it falls to zero as soon as the finger rests.
  if (_touch != null) {
    _history.addLast((now, _lensAnchor));
    while (_history.length > 2 && now - _history.first.$1 > 0.05) {
      _history.removeFirst();
    }
    _anchorVelocity = _slope(_history);
  }

  _idle = !isActive;
  debugOnTick?.call(this, now);
  return !_idle;
}