include/android/sensor.h

/*
 * Copyright (C) 2010 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 ANDROID_SENSOR_H
#define ANDROID_SENSOR_H

/******************************************************************
 *
 * IMPORTANT NOTICE:
 *
 *   This file is part of Android's set of stable system headers
 *   exposed by the Android NDK (Native Development Kit).
 *
 *   Third-party source AND binary code relies on the definitions
 *   here to be FROZEN ON ALL UPCOMING PLATFORM RELEASES.
 *
 *   - DO NOT MODIFY ENUMS (EXCEPT IF YOU ADD NEW 32-BIT VALUES)
 *   - DO NOT MODIFY CONSTANTS OR FUNCTIONAL MACROS
 *   - DO NOT CHANGE THE SIGNATURE OF FUNCTIONS IN ANY WAY
 *   - DO NOT CHANGE THE LAYOUT OR SIZE OF STRUCTURES
 */

/*
 * Structures and functions to receive and process sensor events in
 * native code.
 *
 */

#include <sys/types.h>

#include <android/looper.h>

#ifdef __cplusplus
extern "C" {
#endif


/*
 * Sensor types
 * (keep in sync with hardware/sensor.h)
 */

enum {
    ASENSOR_TYPE_ACCELEROMETER      = 1,
    ASENSOR_TYPE_MAGNETIC_FIELD     = 2,
    ASENSOR_TYPE_GYROSCOPE          = 4,
    ASENSOR_TYPE_LIGHT              = 5,
    ASENSOR_TYPE_PROXIMITY          = 8
};

/*
 * Sensor accuracy measure
 */
enum {
    ASENSOR_STATUS_UNRELIABLE       = 0,
    ASENSOR_STATUS_ACCURACY_LOW     = 1,
    ASENSOR_STATUS_ACCURACY_MEDIUM  = 2,
    ASENSOR_STATUS_ACCURACY_HIGH    = 3
};

/*
 * A few useful constants
 */

/* Earth's gravity in m/s^2 */
#define ASENSOR_STANDARD_GRAVITY            (9.80665f)
/* Maximum magnetic field on Earth's surface in uT */
#define ASENSOR_MAGNETIC_FIELD_EARTH_MAX    (60.0f)
/* Minimum magnetic field on Earth's surface in uT*/
#define ASENSOR_MAGNETIC_FIELD_EARTH_MIN    (30.0f)

/*
 * A sensor event.
 */

/* NOTE: Must match hardware/sensors.h */
typedef struct ASensorVector {
    union {
        float v[3];
        struct {
            float x;
            float y;
            float z;
        };
        struct {
            float azimuth;
            float pitch;
            float roll;
        };
    };
    int8_t status;
    uint8_t reserved[3];
} ASensorVector;

/* NOTE: Must match hardware/sensors.h */
typedef struct ASensorEvent {
    int32_t version; /* sizeof(struct ASensorEvent) */
    int32_t sensor;
    int32_t type;
    int32_t reserved0;
    int64_t timestamp;
    union {
        float           data[16];
        ASensorVector   vector;
        ASensorVector   acceleration;
        ASensorVector   magnetic;
        float           temperature;
        float           distance;
        float           light;
        float           pressure;
        float           step_counter;
    };
    int32_t reserved1[4];
} ASensorEvent;


struct ASensorManager;
typedef struct ASensorManager ASensorManager;

struct ASensorEventQueue;
typedef struct ASensorEventQueue ASensorEventQueue;

struct ASensor;
typedef struct ASensor ASensor;
typedef ASensor const* ASensorRef;
typedef ASensorRef const* ASensorList;

/*****************************************************************************/

/*
 * Get a reference to the sensor manager. ASensorManager is a singleton.
 *
 * Example:
 *
 *     ASensorManager* sensorManager = ASensorManager_getInstance();
 *
 */
ASensorManager* ASensorManager_getInstance();


/*
 * Returns the list of available sensors.
 */
int ASensorManager_getSensorList(ASensorManager* manager, ASensorList* list);

/*
 * Returns the default sensor for the given type, or NULL if no sensor
 * of that type exist.
 */
ASensor const* ASensorManager_getDefaultSensor(ASensorManager* manager, int type);

/*
 * Creates a new sensor event queue and associate it with a looper.
 */
ASensorEventQueue* ASensorManager_createEventQueue(ASensorManager* manager,
        ALooper* looper, int ident, ALooper_callbackFunc callback, void* data);

/*
 * Destroys the event queue and free all resources associated to it.
 */
int ASensorManager_destroyEventQueue(ASensorManager* manager, ASensorEventQueue* queue);


/*****************************************************************************/

/*
 * Enable the selected sensor. Returns a negative error code on failure.
 */
int ASensorEventQueue_enableSensor(ASensorEventQueue* queue, ASensor const* sensor);

/*
 * Disable the selected sensor. Returns a negative error code on failure.
 */
int ASensorEventQueue_disableSensor(ASensorEventQueue* queue, ASensor const* sensor);

/*
 * Sets the delivery rate of events in microseconds for the given sensor.
 * Note that this is a hint only, generally event will arrive at a higher
 * rate. It is an error to set a rate inferior to the value returned by
 * ASensor_getMinDelay().
 * Returns a negative error code on failure.
 */
int ASensorEventQueue_setEventRate(ASensorEventQueue* queue, ASensor const* sensor, int32_t usec);

/*
 * Returns true if there are one or more events available in the
 * sensor queue.  Returns 1 if the queue has events; 0 if
 * it does not have events; and a negative value if there is an error.
 */
int ASensorEventQueue_hasEvents(ASensorEventQueue* queue);

/*
 * Returns the next available events from the queue.  Returns a negative
 * value if no events are available or an error has occurred, otherwise
 * the number of events returned.
 *
 * Examples:
 *   ASensorEvent event;
 *   ssize_t numEvent = ASensorEventQueue_getEvents(queue, &event, 1);
 *
 *   ASensorEvent eventBuffer[8];
 *   ssize_t numEvent = ASensorEventQueue_getEvents(queue, eventBuffer, 8);
 *
 */
ssize_t ASensorEventQueue_getEvents(ASensorEventQueue* queue,
                ASensorEvent* events, size_t count);


/*****************************************************************************/

/*
 * Returns this sensor's name (non localized)
 */
const char* ASensor_getName(ASensor const* sensor);

/*
 * Returns this sensor's vendor's name (non localized)
 */
const char* ASensor_getVendor(ASensor const* sensor);

/*
 * Return this sensor's type
 */
int ASensor_getType(ASensor const* sensor);

/*
 * Returns this sensors's resolution
 */
float ASensor_getResolution(ASensor const* sensor);

/*
 * Returns the minimum delay allowed between events in microseconds.
 * A value of zero means that this sensor doesn't report events at a
 * constant rate, but rather only when a new data is available.
 */
int ASensor_getMinDelay(ASensor const* sensor);


#ifdef __cplusplus
};
#endif

#endif // ANDROID_SENSOR_H