modules/camera/3_4/v4l2_gralloc.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.
 */

#ifndef V4L2_CAMERA_HAL_V4L2_GRALLOC_H_
#define V4L2_CAMERA_HAL_V4L2_GRALLOC_H_

#include <linux/videodev2.h>

#include <unordered_map>

#include <hardware/camera3.h>
#include <hardware/gralloc.h>
#include <system/graphics.h>

namespace v4l2_camera_hal {

// Generously allow up to 6MB (the largest JPEG on the RPi camera is about 5MB).
static constexpr size_t V4L2_MAX_JPEG_SIZE = 6000000;

// V4L2Gralloc is a wrapper around relevant parts of a gralloc module,
// with some assistive transformations.
class V4L2Gralloc {
 public:
  // Use this method to create V4L2Gralloc objects. Functionally equivalent
  // to "new V4L2Gralloc", except that it may return nullptr in case of failure.
  static V4L2Gralloc* NewV4L2Gralloc();
  virtual ~V4L2Gralloc();

  // Lock a camera buffer. Uses device buffer length, sets user pointer.
  int lock(const camera3_stream_buffer_t* camera_buffer,
           uint32_t bytes_per_line,
           v4l2_buffer* device_buffer);
  // Unlock a buffer that was locked by this helper (equality determined
  // based on buffer user pointer, not the specific object).
  int unlock(const v4l2_buffer* device_buffer);
  // Release all held locks.
  int unlockAllBuffers();

 private:
  // Constructor is private to allow failing on bad input.
  // Use NewV4L2Gralloc instead.
  V4L2Gralloc(const gralloc_module_t* module);

  const gralloc_module_t* mModule;

  struct BufferData {
    const camera3_stream_buffer_t* camera_buffer;
    // Below fields only used when a ycbcr format transform is necessary.
    std::unique_ptr<android_ycbcr> transform_dest;  // nullptr if no transform.
    uint32_t v4l2_bytes_per_line;
  };
  // Map data pointer : BufferData about that buffer.
  std::unordered_map<void*, const BufferData*> mBufferMap;
};

}  // namespace default_camera_hal

#endif  // V4L2_CAMERA_HAL_V4L2_GRALLOC_H_