int quarterTurns

The number of clockwise quarter turns the child should be rotated.

Source 

int get quarterTurns => _quarterTurns;
void quarterTurns=(int value)

Source 

set quarterTurns(int value) {
  assert(value != null);
  if (_quarterTurns == value)
    return;
  _quarterTurns = value;
  markNeedsLayout();
}