moveBy method

void moveBy(
  1. int delta
)

Moves selection by delta positions with wrapping.

Positive delta moves down, negative moves up. Wraps around at list boundaries.

Implementation

void moveBy(int delta) {
  if (_itemCount == 0) return;
  _selectedIndex = (_selectedIndex + delta + _itemCount) % _itemCount;
  _adjustScroll();
}