device/generic_sensor/public/interfaces/sensor_provider.mojom

// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

module device.mojom;

import "sensor.mojom";

struct SensorReadBuffer {
  // The shared memory handle used to fetch the sensor reading.
  handle<shared_buffer> memory;

  // The offset at which shared buffer must be mapped.
  uint64 offset;

  // The ReportingMode supported by the sensor.
  ReportingMode mode;

  // Note: Each sensor's read buffer contains 4 tightly packed 64-bit floating
  // point fields, its layout is: { double timestamp; double values[3] }.
  // So it has a fixed size 4*8 = 32 bytes.
  const uint64 kReadBufferSize = 32;
};

interface SensorProvider {
  // Gets the sensor interface by the given type.
  //
  // |type| type of the sensor.
  //
  // |sensor_request| the Sensor interface instance to be initialized.
  //
  // |read_buffer| on success will contain the SensorReadBuffer describing the
  //               sensor reading buffer details,
  //               contains null on failure.
  // |client_request| on success contains a request to be bound by the client,
  //                  contains null on failure.
  GetSensor(SensorType type, Sensor& sensor_request) => (
      SensorReadBuffer? read_buffer,
      SensorClient&? client_request);
};