[OpenCV] my utils

cv::Rect2d selectROI(const std::string &video_name, const cv::Mat &frame)
{
    cv::namedWindow(video_name, cv::WINDOW_NORMAL);
    cv::resizeWindow(video_name, frame.cols, frame.rows);
    struct Data
    {
        cv::Point center;
        cv::Rect2d box;

        static void mouseHandler(int event, int x, int y, int flags, void *param)
        {
            Data *data = (Data*)param;
            switch (event)
            {
                // start to select the bounding box
            case cv::EVENT_LBUTTONDOWN:
                data->box = cvRect(x, y, 0, 0);
                data->center = cv::Point2f((float)x, (float)y);
                break;
                // update the selected bounding box
            case cv::EVENT_MOUSEMOVE:
                if (flags == 1)
                {
                    data->box.width = 2 * (x - data->center.x);
                    data->box.height = 2 * (y - data->center.y);
                    data->box.x = data->center.x - data->box.width / 2.0;
                    data->box.y = data->center.y - data->box.height / 2.0;
                }
                break;
                // cleaning up the selected bounding box
            case cv::EVENT_LBUTTONUP:
                if (data->box.width < 0)
                {
                    data->box.x += data->box.width;
                    data->box.width *= -1;
                }
                if (data->box.height < 0)
                {
                    data->box.y += data->box.height;
                    data->box.height *= -1;
                }
                break;
            }
        }
    } data;

    cv::setMouseCallback(video_name, Data::mouseHandler, &data);

    while (cv::waitKey(1) < 0)
    {
        cv::Mat draw = frame.clone();
        rectangle(draw, data.box, cv::Scalar(255, 0, 0), 2, 1);
        cv::imshow(video_name, draw);
    }
    cv::destroyWindow(video_name);
    return data.box;
}


void toGray(const cv::Mat &frame, cv::Mat &gray)
{
    if (frame.channels() > 1)
        cv::cvtColor(frame, gray, CV_BGR2GRAY);
    else
        frame.copyTo(gray);
}

void toRGB(const cv::Mat &frame, cv::Mat &rgb)
{
    if (frame.channels() == 1)
        cv::cvtColor(frame, rgb, CV_GRAY2RGB);
    else
        frame.copyTo(rgb);
}

void drawBoundingBox(cv::Mat image, std::vector<cv::Point2f> bb, cv::Scalar colour)
{
    for (unsigned i = 0; i < bb.size() - 1; i++) {
        line(image, bb[i], bb[i + 1], colour, 2);
    }
    line(image, bb[bb.size() - 1], bb[0], colour, 2);
}

void drawDot(cv::Mat image, std::vector<cv::Point2f> bb, cv::Scalar colour)
{
    for (unsigned i = 0; i < bb.size() - 1; i++)
    {
        //line(image, bb[i], bb[i + 1], colour, 2);
        cv::circle(image, bb[i], 2, colour, 2);
    }
    cv::circle(image, bb[bb.size() - 1], 2, colour, 2);
}



std::vector<cv::Point2f> Points(std::vector<cv::KeyPoint> keypoints)
{
    std::vector<cv::Point2f> res;
    for (unsigned i = 0; i < keypoints.size(); i++) {
        res.push_back(keypoints[i].pt);
    }
    return res;
}

std::string paddingZeros(int num, int max_zeros)
{
    std::ostringstream ss;
    ss << std::setw(max_zeros) << std::setfill('0') << num;
    return ss.str();
}

std::string cv_makeFilename(std::string path_pattern, int index, cv_FileSuffix format)
{
    std::string format_1 = "";
    switch (format)
    {
    case JPEG:  format_1 += ".jpeg";
    case PNG:   format_1 += ".png";
    default:    format_1 += " ";
    }
    std::string save_index = paddingZeros(index + 1, 4);
    return (path_pattern + save_index + format_1);
}