final int size = fixations.size();
if (size < 2) return;
final Fixation a = fixations.get(size - 2);
final Fixation b = fixations.get(size - 1);
final int x1 = a.getCenter().x;
final int x2 = b.getCenter().x;
final int delta = x2 - x1;
final FixationLineUtil fixationLineUtil = new FixationLineUtil(fixationLine);
final Rectangle r = fixationLineUtil.getRectangle();