imshow microbench

#include <opencv2/opencv.hpp>
#include <cstdint>
#include <chrono>
#include <iostream>

int main()
{
    using std::chrono::high_resolution_clock;
    using std::chrono::duration_cast;
    using std::chrono::microseconds;

    cv::Mat img(cv::Mat::zeros(1200, 1600, CV_8UC3));

    high_resolution_clock::time_point t1 = high_resolution_clock::now();

    for (uint32_t i(0); i < 256; ++i) {
        cv::imshow("foo", img);
        cv::waitKey(1);
        img += 1;
    }

    high_resolution_clock::time_point t2 = high_resolution_clock::now();

    auto duration = duration_cast<microseconds>(t2 - t1).count();
    double t_ms(static_cast<double>(duration) / 1000.0);
    std::cout
        << "Total = " << t_ms << " ms\n"
        << "Iteration = " << (t_ms / 256) << " ms\n"
        << "FPS = " << (256 / t_ms * 1000.0) << "\n";
    return 0;
}