code: public PointF getScrollPosition() {
          Drawable drawable = getDrawable();
          if (drawable == null) {
              return null;
          }
          int drawableWidth = drawable.getIntrinsicWidth();
          int drawableHeight = drawable.getIntrinsicHeight();
  
          PointF point = transformCoordTouchToBitmap(viewWidth / 2, viewHeight / 2, true);
          point.x /= drawableWidth;
          point.y /= drawableHeight;
          return point;
      }
docs: Return the point at the center of the zoomed image. The PointF coordinates range
  in value between 0 and 1 and the focus point is denoted as a fraction from the left
  and top of the view. For example, the top left corner of the image would be (0, 0).
  And the bottom right corner would be (1, 1).
  
  @return PointF representing the scroll position of the zoomed image.