modules/camera/3_4/V4L2Camera.h

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// Loosely based on hardware/libhardware/modules/camera/ExampleCamera.h

#ifndef V4L2_CAMERA_H
#define V4L2_CAMERA_H

#include <array>
#include <string>
#include <vector>

#include <nativehelper/ScopedFd.h>
#include <system/camera_metadata.h>

#include "ArrayVector.h"
#include "Camera.h"
#include "Common.h"
#include "V4L2Gralloc.h"

namespace v4l2_camera_hal {
// V4L2Camera is a specific V4L2-supported camera device. The Camera object
// contains all logic common between all cameras (e.g. front and back cameras),
// while a specific camera device (e.g. V4L2Camera) holds all specific
// metadata and logic about that device.
class V4L2Camera : public default_camera_hal::Camera {
public:
  // Use this method to create V4L2Camera objects. Functionally equivalent
  // to "new V4L2Camera", except that it may return nullptr in case of failure.
  static V4L2Camera* NewV4L2Camera(int id, const std::string path);
  ~V4L2Camera();

private:
  // Constructor private to allow failing on bad input.
  // Use NewV4L2Camera instead.
  V4L2Camera(int id, const std::string path,
             std::unique_ptr<V4L2Gralloc> gralloc);

  // default_camera_hal::Camera virtual methods.
  // Connect to the device: open dev nodes, etc.
  int connect() override;
  // Disconnect from the device: close dev nodes, etc.
  void disconnect() override;
  // Initialize static camera characteristics for individual device.
  int initStaticInfo(camera_metadata_t** out) override;
  // Initialize device info: facing, orientation, resource cost,
  // and conflicting devices (/conflicting devices length).
  void initDeviceInfo(camera_info_t* info) override;
  // Initialize whole device (templates/etc) when opened.
  int initDevice() override;
  // Verify stream configuration is device-compatible.
  bool isSupportedStreamSet(default_camera_hal::Stream** streams,
                            int count, uint32_t mode) override;
  // Set up the device for a stream, and get the maximum number of
  // buffers that stream can handle (max_buffers is an output parameter).
  int setupStream(default_camera_hal::Stream* stream,
                  uint32_t* max_buffers) override;
  // Verify settings are valid for a capture with this device.
  bool isValidCaptureSettings(const camera_metadata_t* settings) override;
  // Enqueue a buffer to receive data from the camera.
  int enqueueBuffer(const camera3_stream_buffer_t* camera_buffer) override;
  // Get the shutter time and updated settings for the most recent frame.
  // The metadata parameter is both an input and output; frame-specific
  // result fields should be appended to what is passed in.
  int getResultSettings(camera_metadata_t** metadata, uint64_t* timestamp);

  // Helper functions for V4L2 functionality.
  int streamOn();
  int streamOff();
  int setFormat(const default_camera_hal::Stream* stream);
  int setupBuffers();
  int dequeueBuffer(v4l2_buffer* buffer);

  // HAL <-> V4L2 conversions.
  uint32_t halToV4L2PixelFormat(int hal_format);  // 0 for unrecognized.
  int V4L2ToHalPixelFormat(uint32_t v4l2_format);  // -1 for unrecognized.

  // The camera device path. For example, /dev/video0.
  const std::string mDevicePath;
  // The opened device fd.
  ScopedFd mDeviceFd;
  // Gralloc helper.
  std::unique_ptr<V4L2Gralloc> mGralloc;
  // Lock protecting use of the device.
  android::Mutex mDeviceLock;
  // Wrapper around ioctl.
  template<typename T>
  int ioctlLocked(int request, T data);

  // Current output stream settings.
  uint32_t mOutStreamType;
  uint32_t mOutStreamFormat;
  uint32_t mOutStreamWidth;
  uint32_t mOutStreamHeight;
  uint32_t mOutStreamBytesPerLine;
  uint32_t mOutStreamMaxBuffers;

  bool mTemplatesInitialized;
  int initTemplates();

  // Camera characteristics.
  bool mCharacteristicsInitialized;  // If false, characteristics are invalid.
  // Fixed characteristics.
  float mAperture;
  float mFilterDensity;
  float mFocalLength;
  int32_t mOrientation;
  std::array<float, 2> mPhysicalSize;  // {width, height}, in mm.
  std::array<int32_t, 4> mPixelArraySize;  // {xmin, ymin, width, height}.
  uint8_t mCropType;
  float mMaxZoom;
  std::array<int32_t, 2> mAeCompensationRange;  // {min, max}.
  camera_metadata_rational mAeCompensationStep;
  uint8_t mAeLockAvailable;
  uint8_t mAwbLockAvailable;
  uint8_t mFlashAvailable;
  float mFocusDistance;
  int32_t mMaxRawOutputStreams;
  int32_t mMaxYuvOutputStreams;
  int32_t mMaxJpegOutputStreams;
  int32_t mMaxInputStreams;
  std::vector<int32_t> mSupportedFormats;
  // Variable characteristics available options.
  std::vector<uint8_t> mAeModes;
  std::vector<uint8_t> mAeAntibandingModes;
  std::vector<uint8_t> mAfModes;
  std::vector<uint8_t> mAwbModes;
  std::vector<uint8_t> mSceneModes;
  std::vector<uint8_t> mControlModes;
  std::vector<uint8_t> mEffects;
  std::vector<uint8_t> mLeds;
  std::vector<uint8_t> mOpticalStabilizationModes;
  std::vector<uint8_t> mVideoStabilizationModes;
  // {format, width, height, direction} (input or output).
  ArrayVector<int32_t, 4> mStreamConfigs;
  // {format, width, height, duration} (duration in ns).
  ArrayVector<int64_t, 4> mMinFrameDurations;
  int64_t mMaxFrameDuration;
  // {format, width, height, duration} (duration in ns).
  ArrayVector<int64_t, 4> mStallDurations;
  // {min, max} (in fps).
  ArrayVector<int32_t, 2> mFpsRanges;

  // Initialize characteristics and set mCharacteristicsInitialized to True.
  int initCharacteristics();

  DISALLOW_COPY_AND_ASSIGN(V4L2Camera);
};

} // namespace v4l2_camera_hal

#endif // V4L2_CAMERA_H