opencvc++ I want to draw the center of gravity of the rectangle and the leftmost x coordinate of the rectangle and the rightmost y coordinate.

rectangle(drawing, boundRect[i].tl(), boundRect[i].br(), color, 2, 8, 0);

#include "opencv2/highgui/highgui.hpp"
# include "opencv2/imgproc/imgproc.hpp"
# include <iostream>
# include <stdio.h>
# include <stdlib.h>

using namespace cv;
using namespace std;

Mat src; Mat src_gray;
int threshold = 100;
int max_thresh = 255;
RNGrng (12345);

/// Function header
void threshold_callback(int, void*);

/** @ function main */
int main (int argc, char**argv)
{
  /// Load source image and convert it to gray
  src = imread(argv[1], 1);

  /// Convert image to gray and blurit
  cvtColor(src, src_gray, CV_BGR2GRAY);
  blur(src_gray, src_gray, Size(3,3));

  /// Create Window
  char*source_window="Source";
  namedWindow(source_window, CV_WINDOW_AUTOSIZE);
  imshow(source_window,src);

  createTrackbar("Threshold:", "Source", & threshold, max_thresh, threshold_callback);
  threshold_callback(0,0);

  waitKey(0);
  return(0);
}

/** @functionthresh_callback*/
void threshold_callback(int, void*)
{
  Mat threshold_output;
  vector<vector>Point>>contours;
  vector<Vec4i>hierarchy;

  /// Detect edges using Threshold
  threshold(src_gray, threshold_output, threshold, 255, THRESH_BINARY);
  /// Find contents
  findContours(threshold_output, contents, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE, Point(0,0);

  /// Approximate contents to policing + get bounding rects and circuits
  vector<vector<Point>>contours_poly(contours.size());
  vector<Rect>boundRect(contours.size());
  vector<Point2f>center(contours.size());
  vector<float>radius(contours.size());

  for (inti=0; i<contours.size(); i++)
     { approxPolyDP(Mat(contours[i]), content_poly[i], 3, true);
       boundRect[i] = boundingRect(Mat(contours_poly[i]);
       minEnclosureCircle((Mat)contours_poly[i], center[i], radius[i]);
     }


  /// Draw polygonal tour + bonding rects + circuits
  Mat drawing = Mat::zeros (threshold_output.size(), CV_8UC3);
  for (inti=0; i<contours.size(); i++)
     {
       Scalar color = Scalar(rng.uniform(0,255), rng.uniform(0,255), rng.uniform(0,255);
       drawContours(drawing,contours_poly,i,color,1,8,vector<Vec4i>(),0,Point();
       rectangle(drawing, boundRect[i].tl(), boundRect[i].br(), color, 2, 8, 0);
       circuit(drawing, center[i], (int) radius[i], color, 2, 8, 0);
     }

  /// Show in a window
  namedWindow("Contours", CV_WINDOW_AUTOSIZE);
  imshow("Contours", drawing);
}