How to refresh the displayed window of imshow? - opencv

Question

Every time I click on the displayed window, I want a circle to be drawn. The following code does not refresh the window. How to do so?
#include <iostream>
#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;
const string filename = "family.jpg";
const string sourceWindow = "source";
void onMouse(int event, int x, int y, int flags, void* param)
{
Mat* image = reinterpret_cast<Mat*>(param);
switch (event)
{
case cv::EVENT_LBUTTONDOWN:
cout << "at (" << x << "," << y << ") values is: "
<< static_cast<int>(image->at<uchar>(Point(x, y))) << endl;
circle(*image, Point(x, y), 65, 0, 5);
break;
}
}
void main()
{
Mat src = imread(filename, IMREAD_GRAYSCALE);
if (!src.empty())
{
namedWindow(sourceWindow, WINDOW_NORMAL);
imshow(sourceWindow, src);
setMouseCallback(sourceWindow, onMouse, reinterpret_cast<void*>(&src));
}
waitKey(0);
}

Answer 1

Just as it is done for video capturing (see VideoCapture)
You simply call imshowagain with the new image.
void onMouse(int event, int x, int y, int flags, void* param)
{
Mat* image = reinterpret_cast<Mat*>(param);
switch (event)
{
case cv::EVENT_LBUTTONDOWN:
cout << "at (" << x << "," << y << ") values is: "
<< static_cast<int>(image->at<uchar>(Point(x, y))) << endl;
circle(*image, Point(x, y), 65, 0, 5);
imshow(sourceWindow, image);
break;
}
}