code: public void zoomToPoint(float scale, PointF imagePoint, PointF viewPoint) {
      FLog.v(TAG, "zoomToPoint");
      calculateZoomToPointTransform(mActiveTransform, scale, imagePoint, viewPoint, LIMIT_ALL);
      onTransformChanged();
    }
docs: Zooms to the desired scale and positions the image so that the given image point corresponds
  to the given view point.
  
  @param scale desired scale, will be limited to {min, max} scale factor
  @param imagePoint 2D point in image's relative coordinate system (i.e. 0 <= x, y <= 1)
  @param viewPoint 2D point in view's absolute coordinate system