OpenCV Mouse Event Handler 2

OpenCV_Mouse_Event_Handler_2.cpp

#include "opencv2/opencv.hpp"
#include <iostream>

using namespace cv;
using namespace std;

Mat frame;

void mouseEventHandler(int event, int x, int y, int flags, void* param)
{
     if ( flags == (EVENT_FLAG_CTRLKEY + EVENT_FLAG_LBUTTON) )
     {
          cout << "Left mouse button is clicked while pressing CTRL key - position (" << x << ", " << y << ")" << endl;
     }
     else if ( flags == (EVENT_FLAG_SHIFTKEY + EVENT_FLAG_RBUTTON) )
     {
          cout << "Right mouse button is clicked while pressing SHIFT key - position (" << x << ", " << y << ")" << endl;
     }
     else if ( event == EVENT_MOUSEMOVE && flags == EVENT_FLAG_ALTKEY)
     {
          cout << "Mouse is moved over the window while pressing ALT key - position (" << x << ", " << y << ")" << endl;
     }
}

void showWindow()
{
  	//Create an autoresize window
	namedWindow("My Window", 1);

	//Set the callback function for any mouse event
	setMouseCallback("My Window", mouseEventHandler, NULL);

	//Show the image
	frame = cv::imread("lena.png");
	imshow("My Window", frame);

	//Wait until user press some key
	waitKey(0);
}