GravitySensor.cpp revision 18343a2fd11583b884d1566a232a75b004fb3813 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdint.h>
18#include <math.h>
19#include <sys/types.h>
20
21#include <utils/Errors.h>
22
23#include <hardware/sensors.h>
24
25#include "GravitySensor.h"
26#include "SensorDevice.h"
27#include "SensorFusion.h"
28
29namespace android {
30// ---------------------------------------------------------------------------
31
32GravitySensor::GravitySensor(sensor_t const* list, size_t count)
33    : mSensorDevice(SensorDevice::getInstance()),
34      mSensorFusion(SensorFusion::getInstance())
35{
36    for (size_t i=0 ; i<count ; i++) {
37        if (list[i].type == SENSOR_TYPE_ACCELEROMETER) {
38            mAccelerometer = Sensor(list + i);
39            break;
40        }
41    }
42}
43
44bool GravitySensor::process(sensors_event_t* outEvent,
45        const sensors_event_t& event)
46{
47    if (event.type == SENSOR_TYPE_ACCELEROMETER) {
48        vec3_t g;
49        if (!mSensorFusion.hasEstimate())
50            return false;
51        const mat33_t R(mSensorFusion.getRotationMatrix());
52        // FIXME: we need to estimate the length of gravity because
53        // the accelerometer may have a small scaling error. This
54        // translates to an offset in the linear-acceleration sensor.
55        g = R[2] * GRAVITY_EARTH;
56
57        *outEvent = event;
58        outEvent->data[0] = g.x;
59        outEvent->data[1] = g.y;
60        outEvent->data[2] = g.z;
61        outEvent->sensor = '_grv';
62        outEvent->type = SENSOR_TYPE_GRAVITY;
63        return true;
64    }
65    return false;
66}
67
68status_t GravitySensor::activate(void* ident, bool enabled) {
69    return mSensorFusion.activate(ident, enabled);
70}
71
72status_t GravitySensor::setDelay(void* ident, int /*handle*/, int64_t ns) {
73    return mSensorFusion.setDelay(ident, ns);
74}
75
76Sensor GravitySensor::getSensor() const {
77    sensor_t hwSensor;
78    hwSensor.name       = "Gravity Sensor";
79    hwSensor.vendor     = "AOSP";
80    hwSensor.version    = 3;
81    hwSensor.handle     = '_grv';
82    hwSensor.type       = SENSOR_TYPE_GRAVITY;
83    hwSensor.maxRange   = GRAVITY_EARTH * 2;
84    hwSensor.resolution = mAccelerometer.getResolution();
85    hwSensor.power      = mSensorFusion.getPowerUsage();
86    hwSensor.minDelay   = mSensorFusion.getMinDelay();
87    Sensor sensor(&hwSensor);
88    return sensor;
89}
90
91// ---------------------------------------------------------------------------
92}; // namespace android
93
94