code: public String pack() {
          String viewStr = view.flattenToString();
          String viewportStr = viewport.flattenToString();
          String visibleStr = visible.flattenToString();
          String imageStr = image.flattenToString();
          return TextUtils.join(DELIMITER, new String[] {
                  viewStr, viewportStr, visibleStr, imageStr
          });
      }
docs: Packs this ViewPosition into string, which can be passed i.e. between activities.
  
  @return Serialized position
  @see #unpack(String)