Detect touch on OpenCV C++ window - c++

Question

I'm trying to open web-cam video and then pause it on first tap and then close it on second tap on a touchscreen display. I'm using OpenCV version 3.4.0.
Currently I can do it by either pressing q key or by closing window but I am unable to do it with screen tap. Here is my code sample:
bool exit_flag = false;
do
{
cv::imshow("window", draw_frame);
int key = cv::waitKey(3);
if (key == 'q'|| cv::getWindowProperty("window", cv::WND_PROP_ASPECT_RATIO) < 0)
{
//do_something
exit_flag = true;
}
} while (!exit_flag);
cv::waitKey(0);
cv::destroyWindow("window");
I tried using cv::EVENT_LBUTTONDOWN but couldn't use it properly to bring any positive results.
Pardon me if code isn't proper, I have created a sample for demonstration and I'm not very good at C++.

Answer 1

If you want to close your imshow window using mouse, you can simply use setMouseCallback. Here is my approach: you can close your window by "q" keyword or by simply clicking to window:
#include "opencv2/highgui/highgui.hpp"
#include <iostream>
using namespace std;
using namespace cv;
static bool exit_flag = false;
static void mouseHandler(int event,int x,int y, int flags,void* param){
if(event==1)
exit_flag = true;
}
int main(int argc, char **argv) {
Mat draw_frame = imread("/ur/image/directory/photo.jpg");
do {
cv::imshow("window", draw_frame);
int key = cv::waitKey(3);
setMouseCallback("window",mouseHandler);
if (key == 'q'|| cv::getWindowProperty("window", cv::WND_PROP_ASPECT_RATIO) < 0)
{
//do_something
exit_flag = true;
}
} while (!exit_flag);
cv::destroyWindow("window");
}