[OpenCV] interactive crop

#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <Windows.h>
#include <opencv2/core.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>


cv::Mat image1, image2;

cv::Mat src, img, ROI;
cv::Rect cropRect(0, 0, 0, 0);
cv::Point P1(0, 0);
cv::Point P2(0, 0);

const std::string winName = "Crop Image";
bool clicked = false;
int saveIndex = 0;
char imgName[15];

void checkBoundary()
{
    //check croping rectangle exceed image boundary
    if (cropRect.width > img.cols - cropRect.x)
        cropRect.width = img.cols - cropRect.x;

    if (cropRect.height > img.rows - cropRect.y)
        cropRect.height = img.rows - cropRect.y;

    if (cropRect.x < 0)
        cropRect.x = 0;

    if (cropRect.y < 0)
        cropRect.height = 0;
}

void showImage()
{
    img = src.clone();
    checkBoundary();
    if (cropRect.width > 0 && cropRect.height > 0)
    {
        ROI = src(cropRect);
        imshow("cropped", ROI);
    }
    cv::rectangle(img, cropRect, cv::Scalar(0, 255, 0), 1, 8, 0);
    imshow(winName, img);
}


void onMouseCrop(int event, int x, int y, int f, void*)
{
    switch (event)
    {
    case  cv::EVENT_LBUTTONDOWN:
        clicked = true;
        P1.x = x;
        P1.y = y;
        P2.x = x;
        P2.y = y;
        break;
    case  cv::EVENT_LBUTTONUP:
        P2.x = x;
        P2.y = y;
        clicked = false;
        break;
    case  cv::EVENT_MOUSEMOVE:
        if (clicked)
        {
            P2.x = x;
            P2.y = y;
        }
        break;
    default:
        break;
    }
    if (clicked)
    {
        if (P1.x > P2.x)
        {
            cropRect.x = P2.x;
            cropRect.width = P1.x - P2.x;
        }
        else
        {
            cropRect.x = P1.x;
            cropRect.width = P2.x - P1.x;
        }

        if (P1.y > P2.y)
        {
            cropRect.y = P2.y;
            cropRect.height = P1.y - P2.y;
        }
        else
        {
            cropRect.y = P1.y;
            cropRect.height = P2.y - P1.y;
        }
    }
    showImage();
}

void displayRoiMessage()
{
    std::cout << "Click and drag for Selection" << std::endl << std::endl;
    std::cout << "------> Press 's' to save" << std::endl << std::endl;

    std::cout << "------> Press '8' to move up" << std::endl;
    std::cout << "------> Press '2' to move down" << std::endl;
    std::cout << "------> Press '6' to move right" << std::endl;
    std::cout << "------> Press '4' to move left" << std::endl << std::endl;

    std::cout << "------> Press 'w' increas top" << std::endl;
    std::cout << "------> Press 'x' increas bottom" << std::endl;
    std::cout << "------> Press 'd' increas right" << std::endl;
    std::cout << "------> Press 'a' increas left" << std::endl << std::endl;

    std::cout << "------> Press 't' decrease top" << std::endl;
    std::cout << "------> Press 'b' decrease bottom" << std::endl;
    std::cout << "------> Press 'h' decrease right" << std::endl;
    std::cout << "------> Press 'f' decrease left" << std::endl << std::endl;

    std::cout << "------> Press 'r' to reset" << std::endl;
    std::cout << "------> Press 'Esc' to quit" << std::endl << std::endl;
}

void performOpcode(char c)
{
    if (c == 's' && ROI.data)
    {
        std::sprintf(imgName, "%d.jpg", saveIndex++);
        cv::imwrite(imgName, ROI);
        std::cout << "  Saved " << imgName << std::endl;
    }
    if (c == '6') cropRect.x++;
    if (c == '4') cropRect.x--;
    if (c == '8') cropRect.y--;
    if (c == '2') cropRect.y++;

    if (c == 'w')
    {
        cropRect.y--;
        cropRect.height++;
    }
    if (c == 'd') cropRect.width++;
    if (c == 'x') cropRect.height++;
    if (c == 'a')
    {
        cropRect.x--;
        cropRect.width++;
    }

    if (c == 't')
    {
        cropRect.y++;
        cropRect.height--;
    }
    if (c == 'h') cropRect.width--;
    if (c == 'b') cropRect.height--;
    if (c == 'f')
    {
        cropRect.x++;
        cropRect.width--;
    }
    if (c == 'r')
    {
        cropRect.x = 0;
        cropRect.y = 0;
        cropRect.width = 0;
        cropRect.height = 0;
    }

    if (c == 27)
    {
        std::cout << "Exit program" << std::endl << std::endl;
        std::exit(EXIT_FAILURE);
    }
}

int main(int argc, char* argv[])
{
    cv::VideoCapture cap;
    cap.open(1);
    if (!cap.isOpened())
    {
        std::cerr << "cannot open camera for capture" << std::endl;
        std::exit(EXIT_FAILURE);
    }
    cv::waitKey(1000);
    // Let user crop a ROI from the input image
    displayRoiMessage();
    cv::namedWindow(winName, cv::WINDOW_NORMAL);
    cv::setMouseCallback(winName, onMouseCrop, nullptr);
    //imshow(winName, src);
    char c;
    do
    {
        cap >> src;
        showImage();
        c = cv::waitKey();
        performOpcode(c);

    } while (c != VK_RETURN);

    // Extract feature
    std::cout << "into feature detection" << std::endl;

    return 0;
}