docs: public void init(int index, Bitmap bitmap, int horizontalOffset, int verticalOffset) {
          this.index = index;
  
          this.groupBitmapHalfHeight = bitmap.getHeight() / 2;
          this.groupBitmapHalfWidth = bitmap.getWidth() / 2;
          this.groupHOffset = horizontalOffset;
          this.groupVOffset = verticalOffset;
      }