code: public float getSize(final Axis axis) {
          float size = 0;
          if (mViewPort != null && mViewPort.isClippingEnabled(axis)) {
              size = mViewPort.get(axis);
          } else if (mContainer != null) {
              size = getSizeImpl(axis);
          }
          return size;
      }
docs: Calculate the layout container size along the axis
  @param axis {@link Axis}
  @return size