Android APIs
public abstract class

SensorManager

extends Object
java.lang.Object
   ↳ android.hardware.SensorManager

Class Overview

SensorManager lets you access the device's sensors. Get an instance of this class by calling Context.getSystemService() with the argument SENSOR_SERVICE.

Always make sure to disable sensors you don't need, especially when your activity is paused. Failing to do so can drain the battery in just a few hours. Note that the system will not disable sensors automatically when the screen turns off.

Note: Don't use this mechanism with a Trigger Sensor, have a look at TriggerEventListener. TYPE_SIGNIFICANT_MOTION is an example of a trigger sensor.

 public class SensorActivity extends Activity, implements SensorEventListener {
     private final SensorManager mSensorManager;
     private final Sensor mAccelerometer;

     public SensorActivity() {
         mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
         mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
     }

     protected void onResume() {
         super.onResume();
         mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_NORMAL);
     }

     protected void onPause() {
         super.onPause();
         mSensorManager.unregisterListener(this);
     }

     public void onAccuracyChanged(Sensor sensor, int accuracy) {
     }

     public void onSensorChanged(SensorEvent event) {
     }
 }
 

Summary

Constants
int AXIS_MINUS_X see remapCoordinateSystem(float[], int, int, float[])
int AXIS_MINUS_Y see remapCoordinateSystem(float[], int, int, float[])
int AXIS_MINUS_Z see remapCoordinateSystem(float[], int, int, float[])
int AXIS_X see remapCoordinateSystem(float[], int, int, float[])
int AXIS_Y see remapCoordinateSystem(float[], int, int, float[])
int AXIS_Z see remapCoordinateSystem(float[], int, int, float[])
int DATA_X This constant was deprecated in API level 3. use Sensor instead.
int DATA_Y This constant was deprecated in API level 3. use Sensor instead.
int DATA_Z This constant was deprecated in API level 3. use Sensor instead.
float GRAVITY_DEATH_STAR_I Gravity (estimate) on the first Death Star in Empire units (m/s^2)
float GRAVITY_EARTH Earth's gravity in SI units (m/s^2)
float GRAVITY_JUPITER Jupiter's gravity in SI units (m/s^2)
float GRAVITY_MARS Mars' gravity in SI units (m/s^2)
float GRAVITY_MERCURY Mercury's gravity in SI units (m/s^2)
float GRAVITY_MOON The Moon's gravity in SI units (m/s^2)
float GRAVITY_NEPTUNE Neptune's gravity in SI units (m/s^2)
float GRAVITY_PLUTO Pluto's gravity in SI units (m/s^2)
float GRAVITY_SATURN Saturn's gravity in SI units (m/s^2)
float GRAVITY_SUN Sun's gravity in SI units (m/s^2)
float GRAVITY_THE_ISLAND Gravity on the island
float GRAVITY_URANUS Uranus' gravity in SI units (m/s^2)
float GRAVITY_VENUS Venus' gravity in SI units (m/s^2)
float LIGHT_CLOUDY luminance under a cloudy sky in lux
float LIGHT_FULLMOON luminance at night with full moon in lux
float LIGHT_NO_MOON luminance at night with no moon in lux
float LIGHT_OVERCAST luminance under an overcast sky in lux
float LIGHT_SHADE luminance in shade in lux
float LIGHT_SUNLIGHT luminance of sunlight in lux
float LIGHT_SUNLIGHT_MAX Maximum luminance of sunlight in lux
float LIGHT_SUNRISE luminance at sunrise in lux
float MAGNETIC_FIELD_EARTH_MAX Maximum magnetic field on Earth's surface
float MAGNETIC_FIELD_EARTH_MIN Minimum magnetic field on Earth's surface
float PRESSURE_STANDARD_ATMOSPHERE Standard atmosphere, or average sea-level pressure in hPa (millibar)
int RAW_DATA_INDEX This constant was deprecated in API level 3. use Sensor instead.
int RAW_DATA_X This constant was deprecated in API level 3. use Sensor instead.
int RAW_DATA_Y This constant was deprecated in API level 3. use Sensor instead.
int RAW_DATA_Z This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_ACCELEROMETER This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_ALL This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_DELAY_FASTEST get sensor data as fast as possible
int SENSOR_DELAY_GAME rate suitable for games
int SENSOR_DELAY_NORMAL rate (default) suitable for screen orientation changes
int SENSOR_DELAY_UI rate suitable for the user interface
int SENSOR_LIGHT This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_MAGNETIC_FIELD This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_MAX This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_MIN This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_ORIENTATION This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_ORIENTATION_RAW This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_PROXIMITY This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_STATUS_ACCURACY_HIGH This sensor is reporting data with maximum accuracy
int SENSOR_STATUS_ACCURACY_LOW This sensor is reporting data with low accuracy, calibration with the environment is needed
int SENSOR_STATUS_ACCURACY_MEDIUM This sensor is reporting data with an average level of accuracy, calibration with the environment may improve the readings
int SENSOR_STATUS_NO_CONTACT The values returned by this sensor cannot be trusted because the sensor had no contact with what it was measuring (for example, the heart rate monitor is not in contact with the user).
int SENSOR_STATUS_UNRELIABLE The values returned by this sensor cannot be trusted, calibration is needed or the environment doesn't allow readings
int SENSOR_TEMPERATURE This constant was deprecated in API level 3. use Sensor instead.
int SENSOR_TRICORDER This constant was deprecated in API level 3. use Sensor instead.
float STANDARD_GRAVITY Standard gravity (g) on Earth.
Public Methods
boolean cancelTriggerSensor(TriggerEventListener listener, Sensor sensor)
Cancels receiving trigger events for a trigger sensor.
boolean flush(SensorEventListener listener)
Flushes the batch FIFO of all the sensors registered for this listener.
static float getAltitude(float p0, float p)
Computes the Altitude in meters from the atmospheric pressure and the pressure at sea level.
static void getAngleChange(float[] angleChange, float[] R, float[] prevR)
Helper function to compute the angle change between two rotation matrices.
Sensor getDefaultSensor(int type)
Use this method to get the default sensor for a given type.
static float getInclination(float[] I)
Computes the geomagnetic inclination angle in radians from the inclination matrix I returned by getRotationMatrix(float[], float[], float[], float[]).
static float[] getOrientation(float[] R, float[] values)
Computes the device's orientation based on the rotation matrix.
static void getQuaternionFromVector(float[] Q, float[] rv)
Helper function to convert a rotation vector to a normalized quaternion.
static boolean getRotationMatrix(float[] R, float[] I, float[] gravity, float[] geomagnetic)

Computes the inclination matrix I as well as the rotation matrix R transforming a vector from the device coordinate system to the world's coordinate system which is defined as a direct orthonormal basis, where:

  • X is defined as the vector product Y.Z (It is tangential to the ground at the device's current location and roughly points East).
static void getRotationMatrixFromVector(float[] R, float[] rotationVector)
Helper function to convert a rotation vector to a rotation matrix.
List<Sensor> getSensorList(int type)
Use this method to get the list of available sensors of a certain type.
int getSensors()
This method was deprecated in API level 3. This method is deprecated, use getSensorList(int) instead
boolean registerListener(SensorListener listener, int sensors, int rate)
This method was deprecated in API level 3. This method is deprecated, use registerListener(SensorEventListener, Sensor, int) instead.
boolean registerListener(SensorListener listener, int sensors)
This method was deprecated in API level 3. This method is deprecated, use registerListener(SensorEventListener, Sensor, int) instead.
boolean registerListener(SensorEventListener listener, Sensor sensor, int rateUs, int maxBatchReportLatencyUs)
Enables batch mode for a sensor with the given rate and maxBatchReportLatency.
boolean registerListener(SensorEventListener listener, Sensor sensor, int rateUs, Handler handler)
Registers a SensorEventListener for the given sensor.
boolean registerListener(SensorEventListener listener, Sensor sensor, int rateUs, int maxBatchReportLatencyUs, Handler handler)
Enables batch mode for a sensor with the given rate and maxBatchReportLatency.
boolean registerListener(SensorEventListener listener, Sensor sensor, int rateUs)
Registers a SensorEventListener for the given sensor.
static boolean remapCoordinateSystem(float[] inR, int X, int Y, float[] outR)

Rotates the supplied rotation matrix so it is expressed in a different coordinate system.

boolean requestTriggerSensor(TriggerEventListener listener, Sensor sensor)
Requests receiving trigger events for a trigger sensor.
void unregisterListener(SensorListener listener)
This method was deprecated in API level 3. This method is deprecated, use unregisterListener(SensorEventListener) instead.
void unregisterListener(SensorListener listener, int sensors)
This method was deprecated in API level 3. This method is deprecated, use unregisterListener(SensorEventListener, Sensor) instead.
void unregisterListener(SensorEventListener listener, Sensor sensor)
Unregisters a listener for the sensors with which it is registered.
void unregisterListener(SensorEventListener listener)
Unregisters a listener for all sensors.
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final int AXIS_MINUS_X

Added in API level 3
Constant Value: 129 (0x00000081)

public static final int AXIS_MINUS_Y

Added in API level 3
Constant Value: 130 (0x00000082)

public static final int AXIS_MINUS_Z

Added in API level 3
Constant Value: 131 (0x00000083)

public static final int AXIS_X

Added in API level 3
Constant Value: 1 (0x00000001)

public static final int AXIS_Y

Added in API level 3
Constant Value: 2 (0x00000002)

public static final int AXIS_Z

Added in API level 3
Constant Value: 3 (0x00000003)

public static final int DATA_X

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Index of the X value in the array returned by onSensorChanged(int, float[])

Constant Value: 0 (0x00000000)

public static final int DATA_Y

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Index of the Y value in the array returned by onSensorChanged(int, float[])

Constant Value: 1 (0x00000001)

public static final int DATA_Z

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Index of the Z value in the array returned by onSensorChanged(int, float[])

Constant Value: 2 (0x00000002)

public static final float GRAVITY_DEATH_STAR_I

Added in API level 1

Gravity (estimate) on the first Death Star in Empire units (m/s^2)

Constant Value: 3.5303614E-7

public static final float GRAVITY_EARTH

Added in API level 1

Earth's gravity in SI units (m/s^2)

Constant Value: 9.80665

public static final float GRAVITY_JUPITER

Added in API level 1

Jupiter's gravity in SI units (m/s^2)

Constant Value: 23.12

public static final float GRAVITY_MARS

Added in API level 1

Mars' gravity in SI units (m/s^2)

Constant Value: 3.71

public static final float GRAVITY_MERCURY

Added in API level 1

Mercury's gravity in SI units (m/s^2)

Constant Value: 3.7

public static final float GRAVITY_MOON

Added in API level 1

The Moon's gravity in SI units (m/s^2)

Constant Value: 1.6

public static final float GRAVITY_NEPTUNE

Added in API level 1

Neptune's gravity in SI units (m/s^2)

Constant Value: 11.0

public static final float GRAVITY_PLUTO

Added in API level 1

Pluto's gravity in SI units (m/s^2)

Constant Value: 0.6

public static final float GRAVITY_SATURN

Added in API level 1

Saturn's gravity in SI units (m/s^2)

Constant Value: 8.96

public static final float GRAVITY_SUN

Added in API level 1

Sun's gravity in SI units (m/s^2)

Constant Value: 275.0

public static final float GRAVITY_THE_ISLAND

Added in API level 1

Gravity on the island

Constant Value: 4.815162

public static final float GRAVITY_URANUS

Added in API level 1

Uranus' gravity in SI units (m/s^2)

Constant Value: 8.69

public static final float GRAVITY_VENUS

Added in API level 1

Venus' gravity in SI units (m/s^2)

Constant Value: 8.87

public static final float LIGHT_CLOUDY

Added in API level 1

luminance under a cloudy sky in lux

Constant Value: 100.0

public static final float LIGHT_FULLMOON

Added in API level 1

luminance at night with full moon in lux

Constant Value: 0.25

public static final float LIGHT_NO_MOON

Added in API level 1

luminance at night with no moon in lux

Constant Value: 0.0010

public static final float LIGHT_OVERCAST

Added in API level 1

luminance under an overcast sky in lux

Constant Value: 10000.0

public static final float LIGHT_SHADE

Added in API level 1

luminance in shade in lux

Constant Value: 20000.0

public static final float LIGHT_SUNLIGHT

Added in API level 1

luminance of sunlight in lux

Constant Value: 110000.0

public static final float LIGHT_SUNLIGHT_MAX

Added in API level 1

Maximum luminance of sunlight in lux

Constant Value: 120000.0

public static final float LIGHT_SUNRISE

Added in API level 1

luminance at sunrise in lux

Constant Value: 400.0

public static final float MAGNETIC_FIELD_EARTH_MAX

Added in API level 1

Maximum magnetic field on Earth's surface

Constant Value: 60.0

public static final float MAGNETIC_FIELD_EARTH_MIN

Added in API level 1

Minimum magnetic field on Earth's surface

Constant Value: 30.0

public static final float PRESSURE_STANDARD_ATMOSPHERE

Added in API level 9

Standard atmosphere, or average sea-level pressure in hPa (millibar)

Constant Value: 1013.25

public static final int RAW_DATA_INDEX

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Offset to the untransformed values in the array returned by onSensorChanged(int, float[])

Constant Value: 3 (0x00000003)

public static final int RAW_DATA_X

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Index of the untransformed X value in the array returned by onSensorChanged(int, float[])

Constant Value: 3 (0x00000003)

public static final int RAW_DATA_Y

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Index of the untransformed Y value in the array returned by onSensorChanged(int, float[])

Constant Value: 4 (0x00000004)

public static final int RAW_DATA_Z

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Index of the untransformed Z value in the array returned by onSensorChanged(int, float[])

Constant Value: 5 (0x00000005)

public static final int SENSOR_ACCELEROMETER

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing an accelerometer. See SensorListener for more details.

Constant Value: 2 (0x00000002)

public static final int SENSOR_ALL

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant that includes all sensors

Constant Value: 127 (0x0000007f)

public static final int SENSOR_DELAY_FASTEST

Added in API level 1

get sensor data as fast as possible

Constant Value: 0 (0x00000000)

public static final int SENSOR_DELAY_GAME

Added in API level 1

rate suitable for games

Constant Value: 1 (0x00000001)

public static final int SENSOR_DELAY_NORMAL

Added in API level 1

rate (default) suitable for screen orientation changes

Constant Value: 3 (0x00000003)

public static final int SENSOR_DELAY_UI

Added in API level 1

rate suitable for the user interface

Constant Value: 2 (0x00000002)

public static final int SENSOR_LIGHT

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing an ambient light sensor See SensorListener for more details.

Constant Value: 16 (0x00000010)

public static final int SENSOR_MAGNETIC_FIELD

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing a magnetic sensor See SensorListener for more details.

Constant Value: 8 (0x00000008)

public static final int SENSOR_MAX

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Largest sensor ID

Constant Value: 64 (0x00000040)

public static final int SENSOR_MIN

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

Smallest sensor ID

Constant Value: 1 (0x00000001)

public static final int SENSOR_ORIENTATION

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing an orientation sensor. See SensorListener for more details.

Constant Value: 1 (0x00000001)

public static final int SENSOR_ORIENTATION_RAW

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing an orientation sensor. See SensorListener for more details.

Constant Value: 128 (0x00000080)

public static final int SENSOR_PROXIMITY

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing a proximity sensor See SensorListener for more details.

Constant Value: 32 (0x00000020)

public static final int SENSOR_STATUS_ACCURACY_HIGH

Added in API level 1

This sensor is reporting data with maximum accuracy

Constant Value: 3 (0x00000003)

public static final int SENSOR_STATUS_ACCURACY_LOW

Added in API level 1

This sensor is reporting data with low accuracy, calibration with the environment is needed

Constant Value: 1 (0x00000001)

public static final int SENSOR_STATUS_ACCURACY_MEDIUM

Added in API level 1

This sensor is reporting data with an average level of accuracy, calibration with the environment may improve the readings

Constant Value: 2 (0x00000002)

public static final int SENSOR_STATUS_NO_CONTACT

Added in API level 20

The values returned by this sensor cannot be trusted because the sensor had no contact with what it was measuring (for example, the heart rate monitor is not in contact with the user).

Constant Value: -1 (0xffffffff)

public static final int SENSOR_STATUS_UNRELIABLE

Added in API level 1

The values returned by this sensor cannot be trusted, calibration is needed or the environment doesn't allow readings

Constant Value: 0 (0x00000000)

public static final int SENSOR_TEMPERATURE

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing a temperature sensor See SensorListener for more details.

Constant Value: 4 (0x00000004)

public static final int SENSOR_TRICORDER

Added in API level 1

This constant was deprecated in API level 3.
use Sensor instead.

A constant describing a Tricorder See SensorListener for more details.

Constant Value: 64 (0x00000040)

public static final float STANDARD_GRAVITY

Added in API level 1

Standard gravity (g) on Earth. This value is equivalent to 1G

Constant Value: 9.80665

Public Methods

public boolean cancelTriggerSensor (TriggerEventListener listener, Sensor sensor)

Added in API level 18

Cancels receiving trigger events for a trigger sensor.

Note that a Trigger sensor will be auto disabled if onTrigger(TriggerEvent) has triggered. This method is provided in case the user wants to explicitly cancel the request to receive trigger events.

Parameters
listener The listener on which the onTrigger(TriggerEvent) is delivered.It should be the same as the one used in requestTriggerSensor(TriggerEventListener, Sensor)
sensor The sensor for which the trigger request should be canceled. If null, it cancels receiving trigger for all sensors associated with the listener.
Returns
  • true if successfully canceled.
Throws
IllegalArgumentException when sensor is a trigger sensor.

public boolean flush (SensorEventListener listener)

Added in API level 19

Flushes the batch FIFO of all the sensors registered for this listener. If there are events in the FIFO of the sensor, they are returned as if the batch timeout in the FIFO of the sensors had expired. Events are returned in the usual way through the SensorEventListener. This call doesn't affect the batch timeout for this sensor. This call is asynchronous and returns immediately. onFlushCompleted is called after all the events in the batch at the time of calling this method have been delivered successfully. If the hardware doesn't support flush, it still returns true and a trivial flush complete event is sent after the current event for all the clients registered for this sensor.

Parameters
listener A SensorEventListener object which was previously used in a registerListener call.
Returns
  • true if the flush is initiated successfully on all the sensors registered for this listener, false if no sensor is previously registered for this listener or flush on one of the sensors fails.
Throws
IllegalArgumentException when listener is null.

public static float getAltitude (float p0, float p)

Added in API level 9

Computes the Altitude in meters from the atmospheric pressure and the pressure at sea level.

Typically the atmospheric pressure is read from a TYPE_PRESSURE sensor. The pressure at sea level must be known, usually it can be retrieved from airport databases in the vicinity. If unknown, you can use PRESSURE_STANDARD_ATMOSPHERE as an approximation, but absolute altitudes won't be accurate.

To calculate altitude differences, you must calculate the difference between the altitudes at both points. If you don't know the altitude as sea level, you can use PRESSURE_STANDARD_ATMOSPHERE instead, which will give good results considering the range of pressure typically involved.

    float altitude_difference = getAltitude(SensorManager.PRESSURE_STANDARD_ATMOSPHERE, pressure_at_point2) - getAltitude(SensorManager.PRESSURE_STANDARD_ATMOSPHERE, pressure_at_point1);

Parameters
p0 pressure at sea level
p atmospheric pressure
Returns
  • Altitude in meters

public static void getAngleChange (float[] angleChange, float[] R, float[] prevR)

Added in API level 9

Helper function to compute the angle change between two rotation matrices. Given a current rotation matrix (R) and a previous rotation matrix (prevR) computes the rotation around the z,x, and y axes which transforms prevR to R. outputs a 3 element vector containing the z,x, and y angle change at indexes 0, 1, and 2 respectively.

Each input matrix is either as a 3x3 or 4x4 row-major matrix depending on the length of the passed array:

If the array length is 9, then the array elements represent this matrix

   /  R[ 0]   R[ 1]   R[ 2]   \
   |  R[ 3]   R[ 4]   R[ 5]   |
   \  R[ 6]   R[ 7]   R[ 8]   /

If the array length is 16, then the array elements represent this matrix

   /  R[ 0]   R[ 1]   R[ 2]   R[ 3]  \
   |  R[ 4]   R[ 5]   R[ 6]   R[ 7]  |
   |  R[ 8]   R[ 9]   R[10]   R[11]  |
   \  R[12]   R[13]   R[14]   R[15]  /

Parameters
angleChange an an array of floats (z, x, and y) in which the angle change is stored
R current rotation matrix
prevR previous rotation matrix

public Sensor getDefaultSensor (int type)

Added in API level 3

Use this method to get the default sensor for a given type. Note that the returned sensor could be a composite sensor, and its data could be averaged or filtered. If you need to access the raw sensors use getSensorList.

Parameters
type of sensors requested
Returns
  • the default sensor matching the requested type if one exists and the application has the necessary permissions, or null otherwise.

public static float getInclination (float[] I)

Added in API level 3

Computes the geomagnetic inclination angle in radians from the inclination matrix I returned by getRotationMatrix(float[], float[], float[], float[]).

Parameters
I inclination matrix see getRotationMatrix(float[], float[], float[], float[]).
Returns
  • The geomagnetic inclination angle in radians.

public static float[] getOrientation (float[] R, float[] values)

Added in API level 3

Computes the device's orientation based on the rotation matrix.

When it returns, the array values is filled with the result:

  • values[0]: azimuth, rotation around the Z axis.
  • values[1]: pitch, rotation around the X axis.
  • values[2]: roll, rotation around the Y axis.

The reference coordinate-system used is different from the world coordinate-system defined for the rotation matrix:

  • X is defined as the vector product Y.Z (It is tangential to the ground at the device's current location and roughly points West).
  • Y is tangential to the ground at the device's current location and points towards the magnetic North Pole.
  • Z points towards the center of the Earth and is perpendicular to the ground.

Inverted world coordinate-system diagram.

All three angles above are in radians and positive in the counter-clockwise direction.

Parameters
R rotation matrix see getRotationMatrix(float[], float[], float[], float[]).
values an array of 3 floats to hold the result.
Returns
  • The array values passed as argument.

public static void getQuaternionFromVector (float[] Q, float[] rv)

Added in API level 9

Helper function to convert a rotation vector to a normalized quaternion. Given a rotation vector (presumably from a ROTATION_VECTOR sensor), returns a normalized quaternion in the array Q. The quaternion is stored as [w, x, y, z]

Parameters
Q an array of floats in which to store the computed quaternion
rv the rotation vector to convert

public static boolean getRotationMatrix (float[] R, float[] I, float[] gravity, float[] geomagnetic)

Added in API level 3

Computes the inclination matrix I as well as the rotation matrix R transforming a vector from the device coordinate system to the world's coordinate system which is defined as a direct orthonormal basis, where:

  • X is defined as the vector product Y.Z (It is tangential to the ground at the device's current location and roughly points East).
  • Y is tangential to the ground at the device's current location and points towards the magnetic North Pole.
  • Z points towards the sky and is perpendicular to the ground.

World coordinate-system diagram.


By definition:

[0 0 g] = R * gravity (g = magnitude of gravity)

[0 m 0] = I * R * geomagnetic (m = magnitude of geomagnetic field)

R is the identity matrix when the device is aligned with the world's coordinate system, that is, when the device's X axis points toward East, the Y axis points to the North Pole and the device is facing the sky.

I is a rotation matrix transforming the geomagnetic vector into the same coordinate space as gravity (the world's coordinate space). I is a simple rotation around the X axis. The inclination angle in radians can be computed with getInclination(float[]).


Each matrix is returned either as a 3x3 or 4x4 row-major matrix depending on the length of the passed array:

If the array length is 16:

   /  M[ 0]   M[ 1]   M[ 2]   M[ 3]  \
   |  M[ 4]   M[ 5]   M[ 6]   M[ 7]  |
   |  M[ 8]   M[ 9]   M[10]   M[11]  |
   \  M[12]   M[13]   M[14]   M[15]  /
This matrix is ready to be used by OpenGL ES's glLoadMatrixf(float[], int).

Note that because OpenGL matrices are column-major matrices you must transpose the matrix before using it. However, since the matrix is a rotation matrix, its transpose is also its inverse, conveniently, it is often the inverse of the rotation that is needed for rendering; it can therefore be used with OpenGL ES directly.

Also note that the returned matrices always have this form:

   /  M[ 0]   M[ 1]   M[ 2]   0  \
   |  M[ 4]   M[ 5]   M[ 6]   0  |
   |  M[ 8]   M[ 9]   M[10]   0  |
   \      0       0       0   1  /

If the array length is 9:

   /  M[ 0]   M[ 1]   M[ 2]  \
   |  M[ 3]   M[ 4]   M[ 5]  |
   \  M[ 6]   M[ 7]   M[ 8]  /

The inverse of each matrix can be computed easily by taking its transpose.

The matrices returned by this function are meaningful only when the device is not free-falling and it is not close to the magnetic north. If the device is accelerating, or placed into a strong magnetic field, the returned matrices may be inaccurate.

Parameters
R is an array of 9 floats holding the rotation matrix R when this function returns. R can be null.

I is an array of 9 floats holding the rotation matrix I when this function returns. I can be null.

gravity is an array of 3 floats containing the gravity vector expressed in the device's coordinate. You can simply use the values returned by a SensorEvent of a Sensor of type TYPE_ACCELEROMETER.

geomagnetic is an array of 3 floats containing the geomagnetic vector expressed in the device's coordinate. You can simply use the values returned by a SensorEvent of a Sensor of type TYPE_MAGNETIC_FIELD.
Returns
  • true on success, false on failure (for instance, if the device is in free fall). On failure the output matrices are not modified.

public static void getRotationMatrixFromVector (float[] R, float[] rotationVector)

Added in API level 9

Helper function to convert a rotation vector to a rotation matrix. Given a rotation vector (presumably from a ROTATION_VECTOR sensor), returns a 9 or 16 element rotation matrix in the array R. R must have length 9 or 16. If R.length == 9, the following matrix is returned:

   /  R[ 0]   R[ 1]   R[ 2]   \
   |  R[ 3]   R[ 4]   R[ 5]   |
   \  R[ 6]   R[ 7]   R[ 8]   /
If R.length == 16, the following matrix is returned:
   /  R[ 0]   R[ 1]   R[ 2]   0  \
   |  R[ 4]   R[ 5]   R[ 6]   0  |
   |  R[ 8]   R[ 9]   R[10]   0  |
   \  0       0       0       1  /

Parameters
R an array of floats in which to store the rotation matrix
rotationVector the rotation vector to convert

public List<Sensor> getSensorList (int type)

Added in API level 3

Use this method to get the list of available sensors of a certain type. Make multiple calls to get sensors of different types or use Sensor.TYPE_ALL to get all the sensors.

Parameters
type of sensors requested
Returns
  • a list of sensors matching the asked type.

public int getSensors ()

Added in API level 1

This method was deprecated in API level 3.
This method is deprecated, use getSensorList(int) instead

Returns
  • available sensors.

public boolean registerListener (SensorListener listener, int sensors, int rate)

Added in API level 1

This method was deprecated in API level 3.
This method is deprecated, use registerListener(SensorEventListener, Sensor, int) instead.

Registers a SensorListener for given sensors.

Parameters
listener sensor listener object
sensors a bit masks of the sensors to register to
rate rate of events. This is only a hint to the system. events may be received faster or slower than the specified rate. Usually events are received faster. The value must be one of SENSOR_DELAY_NORMAL, SENSOR_DELAY_UI, SENSOR_DELAY_GAME, or SENSOR_DELAY_FASTEST.
Returns
  • true if the sensor is supported and successfully enabled

public boolean registerListener (SensorListener listener, int sensors)

Added in API level 1

This method was deprecated in API level 3.
This method is deprecated, use registerListener(SensorEventListener, Sensor, int) instead.

Registers a listener for given sensors.

Parameters
listener sensor listener object
sensors a bit masks of the sensors to register to
Returns
  • true if the sensor is supported and successfully enabled

public boolean registerListener (SensorEventListener listener, Sensor sensor, int rateUs, int maxBatchReportLatencyUs)

Added in API level 19

Enables batch mode for a sensor with the given rate and maxBatchReportLatency. If the underlying hardware does not support batch mode, this defaults to registerListener(SensorEventListener, Sensor, int) and other parameters are ignored. In non-batch mode, all sensor events must be reported as soon as they are detected. While in batch mode, sensor events do not need to be reported as soon as they are detected. They can be temporarily stored in batches and reported in batches, as long as no event is delayed by more than "maxBatchReportLatency" microseconds. That is, all events since the previous batch are recorded and returned all at once. This allows to reduce the amount of interrupts sent to the SoC, and allows the SoC to switch to a lower power state (Idle) while the sensor is capturing and batching data.

Registering to a sensor in batch mode will not prevent the SoC from going to suspend mode. In this case, the sensor will continue to gather events and store it in a hardware FIFO. If the FIFO gets full before the AP wakes up again, some events will be lost, as the older events get overwritten by new events in the hardware FIFO. This can be avoided by holding a wake lock. If the application holds a wake lock, the SoC will not go to suspend mode, so no events will be lost, as the events will be reported before the FIFO gets full.

Batching is always best effort. If a different application requests updates in continuous mode, this application will also get events in continuous mode. Batch mode updates can be unregistered by calling unregisterListener(SensorEventListener).

Note: Don't use this method with a one shot trigger sensor such as TYPE_SIGNIFICANT_MOTION. Use requestTriggerSensor(TriggerEventListener, Sensor) instead.

Parameters
listener A SensorEventListener object that will receive the sensor events. If the application is interested in receiving flush complete notifications, it should register with SensorEventListener2 instead.
sensor The Sensor to register to.
rateUs The desired delay between two consecutive events in microseconds. This is only a hint to the system. Events may be received faster or slower than the specified rate. Usually events are received faster. Can be one of SENSOR_DELAY_NORMAL, SENSOR_DELAY_UI, SENSOR_DELAY_GAME, SENSOR_DELAY_FASTEST or the delay in microseconds.
maxBatchReportLatencyUs An event in the batch can be delayed by at most maxBatchReportLatency microseconds. More events can be batched if this value is large. If this is set to zero, batch mode is disabled and events are delivered in continuous mode as soon as they are available which is equivalent to calling registerListener(SensorEventListener, Sensor, int).
Returns
  • true if batch mode is successfully enabled for this sensor, false otherwise.

public boolean registerListener (SensorEventListener listener, Sensor sensor, int rateUs, Handler handler)

Added in API level 3

Registers a SensorEventListener for the given sensor. Events are delivered in continuous mode as soon as they are available. To reduce the battery usage, use registerListener(SensorEventListener, Sensor, int, int) which enables batch mode for the sensor.

Note: Don't use this method with a one shot trigger sensor such as TYPE_SIGNIFICANT_MOTION. Use requestTriggerSensor(TriggerEventListener, Sensor) instead.

Parameters
listener A SensorEventListener object.
sensor The Sensor to register to.
rateUs The rate sensor events are delivered at. This is only a hint to the system. Events may be received faster or slower than the specified rate. Usually events are received faster. The value must be one of SENSOR_DELAY_NORMAL, SENSOR_DELAY_UI, SENSOR_DELAY_GAME, or SENSOR_DELAY_FASTEST. or, the desired delay between events in microseconds. Specifying the delay in microseconds only works from Android 2.3 (API level 9) onwards. For earlier releases, you must use one of the SENSOR_DELAY_* constants.
handler The Handler the sensor events will be delivered to.
Returns
  • true if the sensor is supported and successfully enabled.

public boolean registerListener (SensorEventListener listener, Sensor sensor, int rateUs, int maxBatchReportLatencyUs, Handler handler)

Added in API level 19

Enables batch mode for a sensor with the given rate and maxBatchReportLatency.

Parameters
listener A SensorEventListener object that will receive the sensor events. If the application is interested in receiving flush complete notifications, it should register with SensorEventListener2 instead.
sensor The Sensor to register to.
rateUs The desired delay between two consecutive events in microseconds. This is only a hint to the system. Events may be received faster or slower than the specified rate. Usually events are received faster. Can be one of SENSOR_DELAY_NORMAL, SENSOR_DELAY_UI, SENSOR_DELAY_GAME, SENSOR_DELAY_FASTEST or the delay in microseconds.
maxBatchReportLatencyUs An event in the batch can be delayed by at most maxBatchReportLatency microseconds. More events can be batched if this value is large. If this is set to zero, batch mode is disabled and events are delivered in continuous mode as soon as they are available which is equivalent to calling registerListener(SensorEventListener, Sensor, int).
handler The Handler the sensor events will be delivered to.
Returns
  • true if batch mode is successfully enabled for this sensor, false otherwise.

public boolean registerListener (SensorEventListener listener, Sensor sensor, int rateUs)

Added in API level 3

Registers a SensorEventListener for the given sensor.

Note: Don't use this method with a one shot trigger sensor such as TYPE_SIGNIFICANT_MOTION. Use requestTriggerSensor(TriggerEventListener, Sensor) instead.

Parameters
listener A SensorEventListener object.
sensor The Sensor to register to.
rateUs The rate sensor events are delivered at. This is only a hint to the system. Events may be received faster or slower than the specified rate. Usually events are received faster. The value must be one of SENSOR_DELAY_NORMAL, SENSOR_DELAY_UI, SENSOR_DELAY_GAME, or SENSOR_DELAY_FASTEST or, the desired delay between events in microseconds. Specifying the delay in microseconds only works from Android 2.3 (API level 9) onwards. For earlier releases, you must use one of the SENSOR_DELAY_* constants.
Returns
  • true if the sensor is supported and successfully enabled.

public static boolean remapCoordinateSystem (float[] inR, int X, int Y, float[] outR)

Added in API level 3

Rotates the supplied rotation matrix so it is expressed in a different coordinate system. This is typically used when an application needs to compute the three orientation angles of the device (see getOrientation(float[], float[])) in a different coordinate system.

When the rotation matrix is used for drawing (for instance with OpenGL ES), it usually doesn't need to be transformed by this function, unless the screen is physically rotated, in which case you can use Display.getRotation() to retrieve the current rotation of the screen. Note that because the user is generally free to rotate their screen, you often should consider the rotation in deciding the parameters to use here.

Examples:

  • Using the camera (Y axis along the camera's axis) for an augmented reality application where the rotation angles are needed:
    • remapCoordinateSystem(inR, AXIS_X, AXIS_Z, outR);

  • Using the device as a mechanical compass when rotation is Surface.ROTATION_90:
    • remapCoordinateSystem(inR, AXIS_Y, AXIS_MINUS_X, outR);

    Beware of the above example. This call is needed only to account for a rotation from its natural orientation when calculating the rotation angles (see getOrientation(float[], float[])). If the rotation matrix is also used for rendering, it may not need to be transformed, for instance if your Activity is running in landscape mode.

Since the resulting coordinate system is orthonormal, only two axes need to be specified.

Parameters
inR the rotation matrix to be transformed. Usually it is the matrix returned by getRotationMatrix(float[], float[], float[], float[]).
X defines on which world axis and direction the X axis of the device is mapped.
Y defines on which world axis and direction the Y axis of the device is mapped.
outR the transformed rotation matrix. inR and outR should not be the same array.
Returns
  • true on success. false if the input parameters are incorrect, for instance if X and Y define the same axis. Or if inR and outR don't have the same length.

public boolean requestTriggerSensor (TriggerEventListener listener, Sensor sensor)

Added in API level 18

Requests receiving trigger events for a trigger sensor.

When the sensor detects a trigger event condition, such as significant motion in the case of the TYPE_SIGNIFICANT_MOTION, the provided trigger listener will be invoked once and then its request to receive trigger events will be canceled. To continue receiving trigger events, the application must request to receive trigger events again.

Parameters
listener The listener on which the onTrigger(TriggerEvent) will be delivered.
sensor The sensor to be enabled.
Returns
  • true if the sensor was successfully enabled.
Throws
IllegalArgumentException when sensor is null or not a trigger sensor.

public void unregisterListener (SensorListener listener)

Added in API level 1

This method was deprecated in API level 3.
This method is deprecated, use unregisterListener(SensorEventListener) instead.

Unregisters a listener for all sensors.

Parameters
listener a SensorListener object

public void unregisterListener (SensorListener listener, int sensors)

Added in API level 1

This method was deprecated in API level 3.
This method is deprecated, use unregisterListener(SensorEventListener, Sensor) instead.

Unregisters a listener for the sensors with which it is registered.

Parameters
listener a SensorListener object
sensors a bit masks of the sensors to unregister from

public void unregisterListener (SensorEventListener listener, Sensor sensor)

Added in API level 3

Unregisters a listener for the sensors with which it is registered.

Note: Don't use this method with a one shot trigger sensor such as TYPE_SIGNIFICANT_MOTION. Use cancelTriggerSensor(TriggerEventListener, Sensor) instead.

Parameters
listener a SensorEventListener object
sensor the sensor to unregister from

public void unregisterListener (SensorEventListener listener)

Added in API level 3

Unregisters a listener for all sensors.

Parameters
listener a SensorListener object