从回调接口获取数据

API 提供了 SetStreamCallback() SetMotionCallback() 函数，来设定各类数据的回调。

注意

一定不要阻塞回调。如果需要长时间处理数据，请将回调作为数据生产者。

参考代码片段：

auto &&api = API::Create(argc, argv);

// Attention: must not block the callbacks.

// Get left image from callback
std::atomic_uint left_count(0);
api->SetStreamCallback(
    Stream::LEFT, [&left_count](const api::StreamData &data) {
      CHECK_NOTNULL(data.img);
      ++left_count;
    });

// Get depth image from callback
api->EnableStreamData(Stream::DEPTH);
std::atomic_uint depth_count(0);
cv::Mat depth;
std::mutex depth_mtx;
api->SetStreamCallback(
    Stream::DEPTH,
    [&depth_count, &depth, &depth_mtx](const api::StreamData &data) {
      UNUSED(data)
      ++depth_count;
      {
        std::lock_guard<std::mutex> _(depth_mtx);
        depth = data.frame;
      }
    });

// Get motion data from callback
std::atomic_uint imu_count(0);
std::shared_ptr<mynteye::ImuData> imu;
std::mutex imu_mtx;
api->SetMotionCallback(
    [&imu_count, &imu, &imu_mtx](const api::MotionData &data) {
      CHECK_NOTNULL(data.imu);
      ++imu_count;
      {
        std::lock_guard<std::mutex> _(imu_mtx);
        imu = data.imu;
      }
    });

api->Start(Source::ALL);

CVPainter painter;

cv::namedWindow("frame");
cv::namedWindow("depth");

unsigned int depth_num = 0;
while (true) {
  api->WaitForStreams();

  auto &&left_data = api->GetStreamData(Stream::LEFT);
  auto &&right_data = api->GetStreamData(Stream::RIGHT);

  // Concat left and right as img
  cv::Mat img;
  cv::hconcat(left_data.frame, right_data.frame, img);

  // Draw img data and size
  painter.DrawImgData(img, *left_data.img);

  // Draw imu data
  if (imu) {
    std::lock_guard<std::mutex> _(imu_mtx);
    painter.DrawImuData(img, *imu);
  }

  // Draw counts
  std::ostringstream ss;
  ss << "left: " << left_count << ", depth: " << depth_count
     << ", imu: " << imu_count;
  painter.DrawText(img, ss.str(), CVPainter::BOTTOM_RIGHT);

  // Show img
  cv::imshow("frame", img);

  // Show depth
  if (!depth.empty()) {
    // Is the depth a new one?
    if (depth_num != depth_count || depth_num == 0) {
      std::lock_guard<std::mutex> _(depth_mtx);
      depth_num = depth_count;
      // LOG(INFO) << "depth_num: " << depth_num;
      ss.str("");
      ss.clear();
      ss << "depth: " << depth_count;
      painter.DrawText(depth, ss.str());
      cv::imshow("depth", depth);  // CV_16UC1
    }
  }

  char key = static_cast<char>(cv::waitKey(1));
  if (key == 27 || key == 'q' || key == 'Q') {  // ESC/Q
    break;
  }
}

api->Stop(Source::ALL);

上述代码，用了 OpenCV 来显示图像和数据。选中显示窗口时，按 ESC/Q 就会结束程序。

完整代码样例，请见 get_from_callbacks.cc 。