code: public boolean computeScroll() {
          boolean needInvalidate = false;
          if (isScrollEnabled && chartScroller.computeScrollOffset(computator)) {
              needInvalidate = true;
          }
          if (isZoomEnabled && chartZoomer.computeZoom(computator)) {
              needInvalidate = true;
          }
          return needInvalidate;
      }
docs: Computes scroll and zoom using {@link ChartScroller} and {@link ChartZoomer}. This method returns true if
  scroll/zoom was computed and chart needs to be invalidated.