openCV 트랙바 콜백 람다식 void* 다운스케일 예제

#include <opencv2/opencv.hpp>
#include <3vmw9.hpp>
 
using namespace cv;
using namespace rv2;
using namespace std;
 
namespace tbr{
 
    static Mat frame, downFrame;
    static int tbrV = 1;
 
}
 
void onChange(int tbrv, void* callee){
/*
    void (*fp)(Mat&, Mat&) = (void(*)(Mat&, Mat&))callee;
    fp(tbr::frame, tbr::downFrame);

//    ((void(*)(Mat&, Mat&))callee)(frame, downFrame);  축약형
*/
    co_i(tbrv, "tbrv :");
}
 
 
 
int main(int argc, char** argv)
{
    VideoCapture cap(0);
 
    namedWindow("window", 1);
    namedWindow("window2", 1);
 
 
 
    createTrackbar("tbr1", "window", &tbr::tbrV, 3, onChange, +[](const Mat& in, Mat& out) { pyrDown(in, out); });
 
 
    for (;;) {
        cap >> tbr::frame;
 
        for (int i = 0; i < tbr::tbrV; ++i)pyrDown(tbr::frame, tbr::downFrame);
 
 
        imshow("window", tbr::frame);
        imshow("window2", tbr::downFrame);
 
        c::t c = waitKey(10);
 
        if (c == 27) break;
    }
 
    return 0;
}