Como usar el mouse con opencv

mouse.cpp

#include <opencv2\opencv.hpp>

using namespace cv;
using namespace std;

static void onMouse( int event, int x, int y, int, void* )
{
  string msg = "mouse - movido: X = " + to_string(x) + " Y = " + to_string(y);
	Mat img(200, 650, CV_8UC3);

	switch (event)
	{
	case CV_EVENT_MOUSEMOVE:
		putText(img, msg, Point(10,100), 4, 1, CV_RGB(0,255,0), 0, CV_AA );
		imshow("Uso del raton", img);
		break;
	case CV_EVENT_LBUTTONDOWN   :  break;
	case CV_EVENT_RBUTTONDOWN   :  break;
	case CV_EVENT_MBUTTONDOWN   :  break;
	case CV_EVENT_LBUTTONUP     :  break;
	case CV_EVENT_RBUTTONUP     :  break;
	case CV_EVENT_MBUTTONUP     :  break;
	case CV_EVENT_LBUTTONDBLCLK :  break;
	case CV_EVENT_RBUTTONDBLCLK :  break;
	case CV_EVENT_MBUTTONDBLCLK :  break;
	}

}

int main( int argc, char** argv )
{
	namedWindow( "Uso del raton", 0 );
	setMouseCallback( "Uso del raton", onMouse);
	waitKey();

	return 0;
}