给我写一个c++函数，传入一个mat，用dlib找出mat中所有人脸的关键点，并存入full_object_detection数组中，该函数的返回值需要为bool，判断是否成功

以下是一个示例代码：

#include <dlib/image_processing/frontal_face_detector.h>
#include <dlib/image_processing/shape_predictor.h>
#include <dlib/opencv.h>
#include <opencv2/opencv.hpp>
#include <vector>

using namespace dlib;
using namespace std;

bool detect_face_keypoints(cv::Mat &mat, std::vector<full_object_detection> &keypoints) {
  try {
    // 加载人脸检测器
    frontal_face_detector face_detector = get_frontal_face_detector();
    // 加载关键点预测器
    shape_predictor shape_predictor;
    deserialize("shape_predictor_68_face_landmarks.dat") >> shape_predictor;

    // 转换为dlib图像
    cv_image<bgr_pixel> cv_img(mat);
    // 检测人脸
    std::vector<rectangle> faces = face_detector(cv_img);
    // 检测关键点
    for (auto &face : faces) {
      full_object_detection shape = shape_predictor(cv_img, face);
      keypoints.push_back(shape);
    }
    return true;
  } catch (exception &e) {
    return false;
  }
}