Basic graphical user interface with OpenCV

We are going to create a basic user interface with OpenCV. The OpenCV user interface allows us to create windows, add images to it, and move, resize, and destroy it. The user interface is in OpenCV's highui module. In the following code, we are going to learn how to create and show two images by pressing a key to display multiple windows with the image moving in the window on our desktop.

Don't worry about reading the full code; we are going to explain it in small chunks:

#include <iostream> 
#include <string> 
#include <sstream> 
using namespace std; 
 
// OpenCV includes 
#include <opencv2/core.hpp> 
#include <opencv2/highgui.hpp> 
using namespace cv; 
 
int main(int argc, const char** argv) 
{ 
   // Read images 
   Mat lena= imread("../lena.jpg"); 
   # Checking if Lena image has been loaded
   if (!lena.data) {
 cout << "Lena image missing!" << enld;
 return -1;
   }
   Mat photo= imread("../photo.jpg...