aos/vision/image/reader.h

#ifndef AOS_VISION_IMAGE_READER_H_
#define AOS_VISION_IMAGE_READER_H_

#include <inttypes.h>
#include <functional>
#include <string>

#include "aos/common/time.h"
#include "aos/vision/image/V4L2.h"
#include "aos/vision/image/camera_params.pb.h"
#include "aos/vision/image/image_types.h"

namespace camera {

aos::vision::CameraParams MakeCameraParams(int32_t width, int32_t height,
                                           int32_t exposure, int32_t brightness,
                                           int32_t gain, int32_t fps);

class Reader {
 public:
  using ProcessCb = std::function<void(
      aos::vision::DataRef data, aos::monotonic_clock::time_point timestamp)>;
  Reader(const std::string &dev_name, ProcessCb process,
         aos::vision::CameraParams params);

  aos::vision::ImageFormat get_format();

  void HandleFrame();
  void StartAsync() {
    MMapBuffers();
    Start();
  }
  int fd() { return fd_; }

 private:
  void QueueBuffer(v4l2_buffer *buf);
  void InitMMap();
  bool SetCameraControl(uint32_t id, const char *name, int value);
  void Init();
  void Start();
  void MMapBuffers();
  // File descriptor of the camera
  int fd_;
  // Name of the camera device.
  std::string dev_name_;

  ProcessCb process_;

  int tick_id_ = 0;
  // The number of buffers currently queued in v4l2.
  uint32_t queued_;
  struct Buffer;
  // TODO(parker): This should be a smart pointer, but it cannot
  // because the buffers are not ummapped.
  Buffer *buffers_;

  // TODO(parker): The timestamps should be queue insertion timestamps
  // which will remove the impact of kNumBuffers.
  // TODO(parker): Flush the queue (or tweak the FPS) if we fall behind.
  static const unsigned int kNumBuffers = 5;

  // set only at initialize
  aos::vision::CameraParams params_;
};

}  // namespace camera

#endif  // AOS_VISION_IMAGE_READER_H_