private static final float MAX_SWIPE_DISTANCE_FACTOR = .6f;
private static final int REFRESH_TRIGGER_DISTANCE = 120;
private float mTotalDragDistance = -1;
.................................................................

if (getParent() != null && ((View) getParent()).getHeight() > 0) {
     final DisplayMetrics metrics = getResources().getDisplayMetrics();
     mTotalDragDistance = (int) Math.min(
     ((View) getParent()).getHeight() * MAX_SWIPE_DISTANCE_FACTOR,
                        REFRESH_TRIGGER_DISTANCE * metrics.density);
}