method turn

Source

bool turn([int pages = 1]) {
  var cur = _active;
  var idx = _pages.indexOf(cur);
  var next = _pages[(idx + pages) % _pages.length];
  if (cur == next) return false;

  cur._display = _displayNone;
  cur.onEvent(PageEvent.offScreen, this);
  next._display = _display;
  _active = next;
  next.onEvent(PageEvent.onScreen, this);
  return true;
}