1 /* 2 * Copyright (C) 2008 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 package android.hardware; 18 19 import android.compat.annotation.UnsupportedAppUsage; 20 21 /** 22 * This class represents a {@link android.hardware.Sensor Sensor} event and 23 * holds information such as the sensor's type, the time-stamp, accuracy and of 24 * course the sensor's {@link SensorEvent#values data}. 25 * 26 * <p> 27 * <u>Definition of the coordinate system used by the SensorEvent API.</u> 28 * </p> 29 * 30 * <p> 31 * The coordinate-system is defined relative to the screen of the phone in its 32 * default orientation. The axes are not swapped when the device's screen 33 * orientation changes. 34 * </p> 35 * 36 * <p> 37 * The X axis is horizontal and points to the right, the Y axis is vertical and 38 * points up and the Z axis points towards the outside of the front face of the 39 * screen. In this system, coordinates behind the screen have negative Z values. 40 * </p> 41 * 42 * <p> 43 * <center><img src="../../../images/axis_device.png" 44 * alt="Sensors coordinate-system diagram." border="0" /></center> 45 * </p> 46 * 47 * <p> 48 * <b>Note:</b> This coordinate system is different from the one used in the 49 * Android 2D APIs where the origin is in the top-left corner. 50 * </p> 51 * 52 * @see SensorManager 53 * @see SensorEvent 54 * @see Sensor 55 * 56 */ 57 58 public class SensorEvent { 59 /** 60 * <p> 61 * The length and contents of the {@link #values values} array depends on 62 * which {@link android.hardware.Sensor sensor} type is being monitored (see 63 * also {@link SensorEvent} for a definition of the coordinate system used). 64 * </p> 65 * 66 * <h4>{@link android.hardware.Sensor#TYPE_ACCELEROMETER 67 * Sensor.TYPE_ACCELEROMETER}:</h4> All values are in SI units (m/s^2) 68 * 69 * <ul> 70 * <li> values[0]: Acceleration minus Gx on the x-axis </li> 71 * <li> values[1]: Acceleration minus Gy on the y-axis </li> 72 * <li> values[2]: Acceleration minus Gz on the z-axis </li> 73 * </ul> 74 * 75 * <p> 76 * A sensor of this type measures the acceleration applied to the device 77 * (<b>Ad</b>). Conceptually, it does so by measuring forces applied to the 78 * sensor itself (<b>Fs</b>) using the relation: 79 * </p> 80 * 81 * <b><center>Ad = - ∑Fs / mass</center></b> 82 * 83 * <p> 84 * In particular, the force of gravity is always influencing the measured 85 * acceleration: 86 * </p> 87 * 88 * <b><center>Ad = -g - ∑F / mass</center></b> 89 * 90 * <p> 91 * For this reason, when the device is sitting on a table (and obviously not 92 * accelerating), the accelerometer reads a magnitude of <b>g</b> = 9.81 93 * m/s^2 94 * </p> 95 * 96 * <p> 97 * Similarly, when the device is in free-fall and therefore dangerously 98 * accelerating towards to ground at 9.81 m/s^2, its accelerometer reads a 99 * magnitude of 0 m/s^2. 100 * </p> 101 * 102 * <p> 103 * It should be apparent that in order to measure the real acceleration of 104 * the device, the contribution of the force of gravity must be eliminated. 105 * This can be achieved by applying a <i>high-pass</i> filter. Conversely, a 106 * <i>low-pass</i> filter can be used to isolate the force of gravity. 107 * </p> 108 * 109 * <pre class="prettyprint"> 110 * 111 * public void onSensorChanged(SensorEvent event) 112 * { 113 * // alpha is calculated as t / (t + dT) 114 * // with t, the low-pass filter's time-constant 115 * // and dT, the event delivery rate 116 * 117 * final float alpha = 0.8; 118 * 119 * gravity[0] = alpha * gravity[0] + (1 - alpha) * event.values[0]; 120 * gravity[1] = alpha * gravity[1] + (1 - alpha) * event.values[1]; 121 * gravity[2] = alpha * gravity[2] + (1 - alpha) * event.values[2]; 122 * 123 * linear_acceleration[0] = event.values[0] - gravity[0]; 124 * linear_acceleration[1] = event.values[1] - gravity[1]; 125 * linear_acceleration[2] = event.values[2] - gravity[2]; 126 * } 127 * </pre> 128 * 129 * <p> 130 * <u>Examples</u>: 131 * <ul> 132 * <li>When the device lies flat on a table and is pushed on its left side 133 * toward the right, the x acceleration value is positive.</li> 134 * 135 * <li>When the device lies flat on a table, the acceleration value is 136 * +9.81, which correspond to the acceleration of the device (0 m/s^2) minus 137 * the force of gravity (-9.81 m/s^2).</li> 138 * 139 * <li>When the device lies flat on a table and is pushed toward the sky 140 * with an acceleration of A m/s^2, the acceleration value is equal to 141 * A+9.81 which correspond to the acceleration of the device (+A m/s^2) 142 * minus the force of gravity (-9.81 m/s^2).</li> 143 * </ul> 144 * 145 * 146 * <h4>{@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD 147 * Sensor.TYPE_MAGNETIC_FIELD}:</h4> 148 * All values are in micro-Tesla (uT) and measure the ambient magnetic field 149 * in the X, Y and Z axis. 150 * 151 * <h4>{@link android.hardware.Sensor#TYPE_GYROSCOPE Sensor.TYPE_GYROSCOPE}: 152 * </h4> All values are in radians/second and measure the rate of rotation 153 * around the device's local X, Y and Z axis. The coordinate system is the 154 * same as is used for the acceleration sensor. Rotation is positive in the 155 * counter-clockwise direction. That is, an observer looking from some 156 * positive location on the x, y or z axis at a device positioned on the 157 * origin would report positive rotation if the device appeared to be 158 * rotating counter clockwise. Note that this is the standard mathematical 159 * definition of positive rotation and does not agree with the definition of 160 * roll given earlier. 161 * <ul> 162 * <li> values[0]: Angular speed around the x-axis </li> 163 * <li> values[1]: Angular speed around the y-axis </li> 164 * <li> values[2]: Angular speed around the z-axis </li> 165 * </ul> 166 * <p> 167 * Typically the output of the gyroscope is integrated over time to 168 * calculate a rotation describing the change of angles over the time step, 169 * for example: 170 * </p> 171 * 172 * <pre class="prettyprint"> 173 * private static final float NS2S = 1.0f / 1000000000.0f; 174 * private final float[] deltaRotationVector = new float[4](); 175 * private float timestamp; 176 * 177 * public void onSensorChanged(SensorEvent event) { 178 * // This time step's delta rotation to be multiplied by the current rotation 179 * // after computing it from the gyro sample data. 180 * if (timestamp != 0) { 181 * final float dT = (event.timestamp - timestamp) * NS2S; 182 * // Axis of the rotation sample, not normalized yet. 183 * float axisX = event.values[0]; 184 * float axisY = event.values[1]; 185 * float axisZ = event.values[2]; 186 * 187 * // Calculate the angular speed of the sample 188 * float omegaMagnitude = sqrt(axisX*axisX + axisY*axisY + axisZ*axisZ); 189 * 190 * // Normalize the rotation vector if it's big enough to get the axis 191 * if (omegaMagnitude > EPSILON) { 192 * axisX /= omegaMagnitude; 193 * axisY /= omegaMagnitude; 194 * axisZ /= omegaMagnitude; 195 * } 196 * 197 * // Integrate around this axis with the angular speed by the time step 198 * // in order to get a delta rotation from this sample over the time step 199 * // We will convert this axis-angle representation of the delta rotation 200 * // into a quaternion before turning it into the rotation matrix. 201 * float thetaOverTwo = omegaMagnitude * dT / 2.0f; 202 * float sinThetaOverTwo = sin(thetaOverTwo); 203 * float cosThetaOverTwo = cos(thetaOverTwo); 204 * deltaRotationVector[0] = sinThetaOverTwo * axisX; 205 * deltaRotationVector[1] = sinThetaOverTwo * axisY; 206 * deltaRotationVector[2] = sinThetaOverTwo * axisZ; 207 * deltaRotationVector[3] = cosThetaOverTwo; 208 * } 209 * timestamp = event.timestamp; 210 * float[] deltaRotationMatrix = new float[9]; 211 * SensorManager.getRotationMatrixFromVector(deltaRotationMatrix, deltaRotationVector); 212 * // User code should concatenate the delta rotation we computed with the current 213 * // rotation in order to get the updated rotation. 214 * // rotationCurrent = rotationCurrent * deltaRotationMatrix; 215 * } 216 * </pre> 217 * <p> 218 * In practice, the gyroscope noise and offset will introduce some errors 219 * which need to be compensated for. This is usually done using the 220 * information from other sensors, but is beyond the scope of this document. 221 * </p> 222 * <h4>{@link android.hardware.Sensor#TYPE_LIGHT Sensor.TYPE_LIGHT}:</h4> 223 * <ul> 224 * <li>values[0]: Ambient light level in SI lux units </li> 225 * </ul> 226 * 227 * <h4>{@link android.hardware.Sensor#TYPE_PRESSURE Sensor.TYPE_PRESSURE}:</h4> 228 * <ul> 229 * <li>values[0]: Atmospheric pressure in hPa (millibar) </li> 230 * </ul> 231 * 232 * <h4>{@link android.hardware.Sensor#TYPE_PROXIMITY Sensor.TYPE_PROXIMITY}: 233 * </h4> 234 * 235 * <ul> 236 * <li>values[0]: Proximity sensor distance measured in centimeters </li> 237 * </ul> 238 * 239 * <p> 240 * <b>Note:</b> Some proximity sensors only support a binary <i>near</i> or 241 * <i>far</i> measurement. In this case, the sensor should report its 242 * {@link android.hardware.Sensor#getMaximumRange() maximum range} value in 243 * the <i>far</i> state and a lesser value in the <i>near</i> state. 244 * </p> 245 * 246 * <h4>{@link android.hardware.Sensor#TYPE_GRAVITY Sensor.TYPE_GRAVITY}:</h4> 247 * <p>A three dimensional vector indicating the direction and magnitude of gravity. Units 248 * are m/s^2. The coordinate system is the same as is used by the acceleration sensor.</p> 249 * <p><b>Note:</b> When the device is at rest, the output of the gravity sensor should be 250 * identical to that of the accelerometer.</p> 251 * 252 * <h4> 253 * {@link android.hardware.Sensor#TYPE_LINEAR_ACCELERATION Sensor.TYPE_LINEAR_ACCELERATION}: 254 * </h4> A three dimensional vector indicating acceleration along each device axis, not 255 * including gravity. All values have units of m/s^2. The coordinate system is the same as is 256 * used by the acceleration sensor. 257 * <p>The output of the accelerometer, gravity and linear-acceleration sensors must obey the 258 * following relation:</p> 259 * <p><ul>acceleration = gravity + linear-acceleration</ul></p> 260 * 261 * <h4>{@link android.hardware.Sensor#TYPE_ROTATION_VECTOR Sensor.TYPE_ROTATION_VECTOR}:</h4> 262 * <p>The rotation vector represents the orientation of the device as a combination of an 263 * <i>angle</i> and an <i>axis</i>, in which the device has rotated through an angle θ 264 * around an axis <x, y, z>.</p> 265 * <p>The three elements of the rotation vector are 266 * <x*sin(θ/2), y*sin(θ/2), z*sin(θ/2)>, such that the magnitude of the rotation 267 * vector is equal to sin(θ/2), and the direction of the rotation vector is equal to the 268 * direction of the axis of rotation.</p> 269 * </p>The three elements of the rotation vector are equal to 270 * the last three components of a <b>unit</b> quaternion 271 * <cos(θ/2), x*sin(θ/2), y*sin(θ/2), z*sin(θ/2)>.</p> 272 * <p>Elements of the rotation vector are unitless. 273 * The x,y, and z axis are defined in the same way as the acceleration 274 * sensor.</p> 275 * The reference coordinate system is defined as a direct orthonormal basis, 276 * where: 277 * </p> 278 * 279 * <ul> 280 * <li>X is defined as the vector product <b>Y.Z</b> (It is tangential to 281 * the ground at the device's current location and roughly points East).</li> 282 * <li>Y is tangential to the ground at the device's current location and 283 * points towards magnetic north.</li> 284 * <li>Z points towards the sky and is perpendicular to the ground.</li> 285 * </ul> 286 * 287 * <p> 288 * <center><img src="../../../images/axis_globe.png" 289 * alt="World coordinate-system diagram." border="0" /></center> 290 * </p> 291 * 292 * <ul> 293 * <li> values[0]: x*sin(θ/2) </li> 294 * <li> values[1]: y*sin(θ/2) </li> 295 * <li> values[2]: z*sin(θ/2) </li> 296 * <li> values[3]: cos(θ/2) </li> 297 * <li> values[4]: estimated heading Accuracy (in radians) (-1 if unavailable)</li> 298 * </ul> 299 * <p> values[3], originally optional, will always be present from SDK Level 18 onwards. 300 * values[4] is a new value that has been added in SDK Level 18. 301 * </p> 302 * 303 * <h4>{@link android.hardware.Sensor#TYPE_ORIENTATION 304 * Sensor.TYPE_ORIENTATION}:</h4> All values are angles in degrees. 305 * 306 * <ul> 307 * <li> values[0]: Azimuth, angle between the magnetic north direction and the 308 * y-axis, around the z-axis (0 to 359). 0=North, 90=East, 180=South, 309 * 270=West 310 * </p> 311 * 312 * <p> 313 * values[1]: Pitch, rotation around x-axis (-180 to 180), with positive 314 * values when the z-axis moves <b>toward</b> the y-axis. 315 * </p> 316 * 317 * <p> 318 * values[2]: Roll, rotation around the y-axis (-90 to 90) 319 * increasing as the device moves clockwise. 320 * </p> 321 * </ul> 322 * 323 * <p> 324 * <b>Note:</b> This definition is different from <b>yaw, pitch and roll</b> 325 * used in aviation where the X axis is along the long side of the plane 326 * (tail to nose). 327 * </p> 328 * 329 * <p> 330 * <b>Note:</b> This sensor type exists for legacy reasons, please use 331 * {@link android.hardware.Sensor#TYPE_ROTATION_VECTOR 332 * rotation vector sensor type} and 333 * {@link android.hardware.SensorManager#getRotationMatrix 334 * getRotationMatrix()} in conjunction with 335 * {@link android.hardware.SensorManager#remapCoordinateSystem 336 * remapCoordinateSystem()} and 337 * {@link android.hardware.SensorManager#getOrientation getOrientation()} to 338 * compute these values instead. 339 * </p> 340 * 341 * <p> 342 * <b>Important note:</b> For historical reasons the roll angle is positive 343 * in the clockwise direction (mathematically speaking, it should be 344 * positive in the counter-clockwise direction). 345 * </p> 346 * 347 * <h4>{@link android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY 348 * Sensor.TYPE_RELATIVE_HUMIDITY}:</h4> 349 * <ul> 350 * <li> values[0]: Relative ambient air humidity in percent </li> 351 * </ul> 352 * <p> 353 * When relative ambient air humidity and ambient temperature are 354 * measured, the dew point and absolute humidity can be calculated. 355 * </p> 356 * <u>Dew Point</u> 357 * <p> 358 * The dew point is the temperature to which a given parcel of air must be 359 * cooled, at constant barometric pressure, for water vapor to condense 360 * into water. 361 * </p> 362 * <center><pre> 363 * ln(RH/100%) + m·t/(T<sub>n</sub>+t) 364 * t<sub>d</sub>(t,RH) = T<sub>n</sub> · ------------------------------ 365 * m - [ln(RH/100%) + m·t/(T<sub>n</sub>+t)] 366 * </pre></center> 367 * <dl> 368 * <dt>t<sub>d</sub></dt> <dd>dew point temperature in °C</dd> 369 * <dt>t</dt> <dd>actual temperature in °C</dd> 370 * <dt>RH</dt> <dd>actual relative humidity in %</dd> 371 * <dt>m</dt> <dd>17.62</dd> 372 * <dt>T<sub>n</sub></dt> <dd>243.12 °C</dd> 373 * </dl> 374 * <p>for example:</p> 375 * <pre class="prettyprint"> 376 * h = Math.log(rh / 100.0) + (17.62 * t) / (243.12 + t); 377 * td = 243.12 * h / (17.62 - h); 378 * </pre> 379 * <u>Absolute Humidity</u> 380 * <p> 381 * The absolute humidity is the mass of water vapor in a particular volume 382 * of dry air. The unit is g/m<sup>3</sup>. 383 * </p> 384 * <center><pre> 385 * RH/100%·A·exp(m·t/(T<sub>n</sub>+t)) 386 * d<sub>v</sub>(t,RH) = 216.7 · ------------------------- 387 * 273.15 + t 388 * </pre></center> 389 * <dl> 390 * <dt>d<sub>v</sub></dt> <dd>absolute humidity in g/m<sup>3</sup></dd> 391 * <dt>t</dt> <dd>actual temperature in °C</dd> 392 * <dt>RH</dt> <dd>actual relative humidity in %</dd> 393 * <dt>m</dt> <dd>17.62</dd> 394 * <dt>T<sub>n</sub></dt> <dd>243.12 °C</dd> 395 * <dt>A</dt> <dd>6.112 hPa</dd> 396 * </dl> 397 * <p>for example:</p> 398 * <pre class="prettyprint"> 399 * dv = 216.7 * 400 * (rh / 100.0 * 6.112 * Math.exp(17.62 * t / (243.12 + t)) / (273.15 + t)); 401 * </pre> 402 * 403 * <h4>{@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE Sensor.TYPE_AMBIENT_TEMPERATURE}: 404 * </h4> 405 * 406 * <ul> 407 * <li> values[0]: ambient (room) temperature in degree Celsius.</li> 408 * </ul> 409 * 410 * 411 * <h4>{@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD_UNCALIBRATED 412 * Sensor.TYPE_MAGNETIC_FIELD_UNCALIBRATED}:</h4> 413 * Similar to {@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD}, 414 * but the hard iron calibration is reported separately instead of being included 415 * in the measurement. Factory calibration and temperature compensation will still 416 * be applied to the "uncalibrated" measurement. Assumptions that the magnetic field 417 * is due to the Earth's poles is avoided. 418 * <p> 419 * The values array is shown below: 420 * <ul> 421 * <li> values[0] = x_uncalib </li> 422 * <li> values[1] = y_uncalib </li> 423 * <li> values[2] = z_uncalib </li> 424 * <li> values[3] = x_bias </li> 425 * <li> values[4] = y_bias </li> 426 * <li> values[5] = z_bias </li> 427 * </ul> 428 * </p> 429 * <p> 430 * x_uncalib, y_uncalib, z_uncalib are the measured magnetic field in X, Y, Z axes. 431 * Soft iron and temperature calibrations are applied. But the hard iron 432 * calibration is not applied. The values are in micro-Tesla (uT). 433 * </p> 434 * <p> 435 * x_bias, y_bias, z_bias give the iron bias estimated in X, Y, Z axes. 436 * Each field is a component of the estimated hard iron calibration. 437 * The values are in micro-Tesla (uT). 438 * </p> 439 * <p> Hard iron - These distortions arise due to the magnetized iron, steel or permanent 440 * magnets on the device. 441 * Soft iron - These distortions arise due to the interaction with the earth's magnetic 442 * field. 443 * </p> 444 * <h4> {@link android.hardware.Sensor#TYPE_GAME_ROTATION_VECTOR 445 * Sensor.TYPE_GAME_ROTATION_VECTOR}:</h4> 446 * Identical to {@link android.hardware.Sensor#TYPE_ROTATION_VECTOR} except that it 447 * doesn't use the geomagnetic field. Therefore the Y axis doesn't 448 * point north, but instead to some other reference, that reference is 449 * allowed to drift by the same order of magnitude as the gyroscope 450 * drift around the Z axis. 451 * <p> 452 * In the ideal case, a phone rotated and returning to the same real-world 453 * orientation will report the same game rotation vector 454 * (without using the earth's geomagnetic field). However, the orientation 455 * may drift somewhat over time. See {@link android.hardware.Sensor#TYPE_ROTATION_VECTOR} 456 * for a detailed description of the values. This sensor will not have 457 * the estimated heading accuracy value. 458 * </p> 459 * 460 * <h4> {@link android.hardware.Sensor#TYPE_GYROSCOPE_UNCALIBRATED 461 * Sensor.TYPE_GYROSCOPE_UNCALIBRATED}:</h4> 462 * All values are in radians/second and measure the rate of rotation 463 * around the X, Y and Z axis. An estimation of the drift on each axis is 464 * reported as well. 465 * <p> 466 * No gyro-drift compensation is performed. Factory calibration and temperature 467 * compensation is still applied to the rate of rotation (angular speeds). 468 * </p> 469 * <p> 470 * The coordinate system is the same as is used for the 471 * {@link android.hardware.Sensor#TYPE_ACCELEROMETER} 472 * Rotation is positive in the counter-clockwise direction (right-hand rule). 473 * That is, an observer looking from some positive location on the x, y or z axis 474 * at a device positioned on the origin would report positive rotation if the device 475 * appeared to be rotating counter clockwise. 476 * The range would at least be 17.45 rad/s (ie: ~1000 deg/s). 477 * <ul> 478 * <li> values[0] : angular speed (w/o drift compensation) around the X axis in rad/s </li> 479 * <li> values[1] : angular speed (w/o drift compensation) around the Y axis in rad/s </li> 480 * <li> values[2] : angular speed (w/o drift compensation) around the Z axis in rad/s </li> 481 * <li> values[3] : estimated drift around X axis in rad/s </li> 482 * <li> values[4] : estimated drift around Y axis in rad/s </li> 483 * <li> values[5] : estimated drift around Z axis in rad/s </li> 484 * </ul> 485 * </p> 486 * <p><b>Pro Tip:</b> Always use the length of the values array while performing operations 487 * on it. In earlier versions, this used to be always 3 which has changed now. </p> 488 * 489 * <h4>{@link android.hardware.Sensor#TYPE_POSE_6DOF 490 * Sensor.TYPE_POSE_6DOF}:</h4> 491 * 492 * A TYPE_POSE_6DOF event consists of a rotation expressed as a quaternion and a translation 493 * expressed in SI units. The event also contains a delta rotation and translation that show 494 * how the device?s pose has changed since the previous sequence numbered pose. 495 * The event uses the cannonical Android Sensor axes. 496 * 497 * 498 * <ul> 499 * <li> values[0]: x*sin(θ/2) </li> 500 * <li> values[1]: y*sin(θ/2) </li> 501 * <li> values[2]: z*sin(θ/2) </li> 502 * <li> values[3]: cos(θ/2) </li> 503 * 504 * 505 * <li> values[4]: Translation along x axis from an arbitrary origin. </li> 506 * <li> values[5]: Translation along y axis from an arbitrary origin. </li> 507 * <li> values[6]: Translation along z axis from an arbitrary origin. </li> 508 * 509 * <li> values[7]: Delta quaternion rotation x*sin(θ/2) </li> 510 * <li> values[8]: Delta quaternion rotation y*sin(θ/2) </li> 511 * <li> values[9]: Delta quaternion rotation z*sin(θ/2) </li> 512 * <li> values[10]: Delta quaternion rotation cos(θ/2) </li> 513 * 514 * <li> values[11]: Delta translation along x axis. </li> 515 * <li> values[12]: Delta translation along y axis. </li> 516 * <li> values[13]: Delta translation along z axis. </li> 517 * 518 * <li> values[14]: Sequence number </li> 519 * 520 * </ul> 521 * 522 * <h4>{@link android.hardware.Sensor#TYPE_STATIONARY_DETECT 523 * Sensor.TYPE_STATIONARY_DETECT}:</h4> 524 * 525 * A TYPE_STATIONARY_DETECT event is produced if the device has been 526 * stationary for at least 5 seconds with a maximal latency of 5 527 * additional seconds. ie: it may take up anywhere from 5 to 10 seconds 528 * afte the device has been at rest to trigger this event. 529 * 530 * The only allowed value is 1.0. 531 * 532 * <ul> 533 * <li> values[0]: 1.0 </li> 534 * </ul> 535 * 536 * <h4>{@link android.hardware.Sensor#TYPE_MOTION_DETECT 537 * Sensor.TYPE_MOTION_DETECT}:</h4> 538 * 539 * A TYPE_MOTION_DETECT event is produced if the device has been in 540 * motion for at least 5 seconds with a maximal latency of 5 541 * additional seconds. ie: it may take up anywhere from 5 to 10 seconds 542 * afte the device has been at rest to trigger this event. 543 * 544 * The only allowed value is 1.0. 545 * 546 * <ul> 547 * <li> values[0]: 1.0 </li> 548 * </ul> 549 * 550 * <h4>{@link android.hardware.Sensor#TYPE_HEART_BEAT 551 * Sensor.TYPE_HEART_BEAT}:</h4> 552 * 553 * A sensor of this type returns an event everytime a hear beat peak is 554 * detected. 555 * 556 * Peak here ideally corresponds to the positive peak in the QRS complex of 557 * an ECG signal. 558 * 559 * <ul> 560 * <li> values[0]: confidence</li> 561 * </ul> 562 * 563 * <p> 564 * A confidence value of 0.0 indicates complete uncertainty - that a peak 565 * is as likely to be at the indicated timestamp as anywhere else. 566 * A confidence value of 1.0 indicates complete certainly - that a peak is 567 * completely unlikely to be anywhere else on the QRS complex. 568 * </p> 569 * 570 * <h4>{@link android.hardware.Sensor#TYPE_LOW_LATENCY_OFFBODY_DETECT 571 * Sensor.TYPE_LOW_LATENCY_OFFBODY_DETECT}:</h4> 572 * 573 * <p> 574 * A sensor of this type returns an event every time the device transitions 575 * from off-body to on-body and from on-body to off-body (e.g. a wearable 576 * device being removed from the wrist would trigger an event indicating an 577 * off-body transition). The event returned will contain a single value to 578 * indicate off-body state: 579 * </p> 580 * 581 * <ul> 582 * <li> values[0]: off-body state</li> 583 * </ul> 584 * 585 * <p> 586 * Valid values for off-body state: 587 * <ul> 588 * <li> 1.0 (device is on-body)</li> 589 * <li> 0.0 (device is off-body)</li> 590 * </ul> 591 * </p> 592 * 593 * <p> 594 * When a sensor of this type is activated, it must deliver the initial 595 * on-body or off-body event representing the current device state within 596 * 5 seconds of activating the sensor. 597 * </p> 598 * 599 * <p> 600 * This sensor must be able to detect and report an on-body to off-body 601 * transition within 1 second of the device being removed from the body, 602 * and must be able to detect and report an off-body to on-body transition 603 * within 5 seconds of the device being put back onto the body. 604 * </p> 605 * 606 * <h4>{@link android.hardware.Sensor#TYPE_ACCELEROMETER_UNCALIBRATED 607 * Sensor.TYPE_ACCELEROMETER_UNCALIBRATED}:</h4> All values are in SI 608 * units (m/s^2) 609 * 610 * Similar to {@link android.hardware.Sensor#TYPE_ACCELEROMETER}, 611 * Factory calibration and temperature compensation will still be applied 612 * to the "uncalibrated" measurement. 613 * 614 * <p> 615 * The values array is shown below: 616 * <ul> 617 * <li> values[0] = x_uncalib without bias compensation </li> 618 * <li> values[1] = y_uncalib without bias compensation </li> 619 * <li> values[2] = z_uncalib without bias compensation </li> 620 * <li> values[3] = estimated x_bias </li> 621 * <li> values[4] = estimated y_bias </li> 622 * <li> values[5] = estimated z_bias </li> 623 * </ul> 624 * </p> 625 * <p> 626 * x_uncalib, y_uncalib, z_uncalib are the measured acceleration in X, Y, Z 627 * axes similar to the {@link android.hardware.Sensor#TYPE_ACCELEROMETER}, 628 * without any bias correction (factory bias compensation and any 629 * temperature compensation is allowed). 630 * x_bias, y_bias, z_bias are the estimated biases. 631 * </p> 632 * 633 * @see GeomagneticField 634 */ 635 public final float[] values; 636 637 /** 638 * The sensor that generated this event. See 639 * {@link android.hardware.SensorManager SensorManager} for details. 640 */ 641 public Sensor sensor; 642 643 /** 644 * The accuracy of this event. See {@link android.hardware.SensorManager 645 * SensorManager} for details. 646 */ 647 public int accuracy; 648 649 /** 650 * The time in nanosecond at which the event happened 651 */ 652 public long timestamp; 653 654 @UnsupportedAppUsage SensorEvent(int valueSize)655 SensorEvent(int valueSize) { 656 values = new float[valueSize]; 657 } 658 } 659
