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/*! @file smomo.h
  @brief Interface file for SmoMo which defines the public interface exposed to SmoMo clients.

  @details SmoMo clients use these interfaces to feed SmoMo required info like frame rate, refresh
  rate, these info are used to update SmoMo internal state.
*/

#ifndef __SMOMO_INTERFACE_H__
#define __SMOMO_INTERFACE_H__

#include <sys/types.h>

#include <vector>
#include <string>

namespace smomo {

typedef int64_t nsecs_t;

/*! @brief This structure defines the layer stats required by SmoMo.

  @sa SmomoIntf::updateSmomoState
*/
struct SmomoLayerStats {
  std::string name;  // layer full name
  int32_t id;    // layer ID
};

/*! @brief This structure defines the buffer stats required by SmoMo.

  @sa SmomoIntf::CollectLayerStats
  @sa SmomoIntf::ShouldPresentNow
*/
struct SmomoBufferStats {
  int32_t id;    // layer ID
  int32_t queued_frames;  // queued frame count of this layer
  bool auto_timestamp;  // whether timestamp was generated automatically
  nsecs_t timestamp;  // layer buffer's timestamp
};

/*! @brief SmoMo interface implemented by SmoMo library.

  @details This class declares prototype for SmoMo public interfaces which must be
  implemented by SmoMo library. SmoMo clients will use these methods to feed required
  info to SmoMo implementation.
*/
class SmomoIntf {
 public:
  virtual ~SmomoIntf() = default;

  /*! @brief Update SmoMo internal state.

    @details This function is called once per each composition so that required layer info are feed
    to SmoMo, the SmoMo uses these info to update its internal state.

    @param[in] layers \link SmomoLayerStats \endlink
    @param[in] refresh_rate current display refresh rate

    @return \link void \endlink
  */
  virtual void UpdateSmomoState(const std::vector<SmomoLayerStats> &layers,
      float refresh_rate) = 0;

  /*! @brief Collect layer buffer stats.

    @details This function is called once new buffer is ready for this layer. It's used to collect
    layer's buffer stats for SmoMo.

    @param[in] \link SmomoBufferStats \endlink

    @return \link void \endlink
  */
  virtual void CollectLayerStats(const SmomoBufferStats &buffer_stats) = 0;

  /*! @brief Is this layer buffer ready to present.

    @details This function is called by SmoMo clients used to check whether this layer buffer is
    due to present.

    @param[in] \link SmomoBufferStats \endlink
    @param[in] next_vsync_time When next VSYNC arrives

    @return \link bool \endlink
  */
  virtual bool ShouldPresentNow(const SmomoBufferStats &buffer_stats,
      const nsecs_t next_vsync_time) = 0;

  /*! @brief Change refresh rate callback type definition.
  */
  using ChangeRefreshRateCallback = std::function<void(int32_t)>;

  /*! @brief Set the callback used by SmoMo to change display refresh rate.

    @details This function is called by SmoMo clients used to set the refresh rate callback.

    @param[in] callback \link ChangeRefreshRateCallback \endlink

    @return \link void \endlink
  */
  virtual void SetChangeRefreshRateCallback(
      const ChangeRefreshRateCallback& callback) = 0;

  /*! @brief Set the refersh rates supported by display.

    @details This function is called to tell SmoMo what refresh rates this display can suport.

    @param[in] refresh_rates The refresh rates list supported by the display

    @return \link void \endlink
  */
  virtual void SetDisplayRefreshRates(const std::vector<float> &refresh_rates) = 0;
};

}  // namespace smomo

#endif  // __SMOMO_INTERFACE_H__