多个检测框，合并成一个大框，或者输出一个最大的框

    cv::Rect largest_rect;
    bool found_largest = false;
    double max_area = 0.0;
    std::string det_name;

    for (auto it = dets.begin(); it != dets.end(); ++it) {
        const Detect& det = it->second;
        double area = det.rect.width * det.rect.height;

        // 如果找到更大的框，更新最大框
        if (area > max_area) {
            max_area = area;
            largest_rect = det.rect;
            found_largest = true;
            det_name=it->first;
        }
    }

合并成一个最大检测框

    // 初始化最小和最大坐标
    int min_x = INT_MAX;
    int min_y = INT_MAX;
    int max_x = INT_MIN;
    int max_y = INT_MIN;

    // 遍历所有的检测框，找到最小和最大坐标
    for (const auto& it : dets) {
        const Detect& det = it.second;

        min_x = std::min(min_x, det.rect.x);
        min_y = std::min(min_y, det.rect.y);
        max_x = std::max(max_x, det.rect.x + det.rect.width);
        max_y = std::max(max_y, det.rect.y + det.rect.height);
    }

    // 创建合并后的矩形框
    cv::Rect largest_rect(min_x, min_y, max_x - min_x, max_y - min_y);