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    41 

    42 #include "genericrotationsensor.h"

    43 #include <QDebug>

    44 #include <qmath.h>

    45 

    46 #define RADIANS_TO_DEGREES 57.2957795

    47 

    48 const char *genericrotationsensor::id("generic.rotation");

    49 

    50 genericrotationsensor::genericrotationsensor(QSensor *sensor)

    51     : QSensorBackend(sensor)

    52 {

    53     accelerometer = new QAccelerometer(this);

    54     accelerometer->addFilter(this);

    55     accelerometer->connectToBackend();

    56 

    57     setReading<QRotationReading>(&m_reading);

    58     setDataRates(accelerometer);

    59 

    60     sensor->setProperty("hasZ", false);

    61 }

    62 

    63 void genericrotationsensor::start()

    64 {

    65     accelerometer->setDataRate(sensor()->dataRate());

    66     accelerometer->start();

    67     if (!accelerometer->isActive())

    68         sensorStopped();

    69     if (accelerometer->isBusy())

    70         sensorBusy();

    71 }

    72 

    73 void genericrotationsensor::stop()

    74 {

    75     accelerometer->stop();

    76 }

    77 

    78 bool genericrotationsensor::filter(QSensorReading *reading)

    79 {

    80     QAccelerometerReading *ar = qobject_cast<QAccelerometerReading*>(reading);

    81     qreal pitch = 0;

    82     qreal roll = 0;

    83 

    84     qreal x = ar->x();

    85     qreal y = ar->y();

    86     qreal z = ar->z();

    87 

    88     // Note that the formula used come from this document:

    89     // http://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf

    90     pitch = qAtan(y / sqrt(x*x + z*z)) * RADIANS_TO_DEGREES;

    91     roll = qAtan(x / sqrt(y*y + z*z)) * RADIANS_TO_DEGREES;

    92     // Roll is a left-handed rotation but we need right-handed rotation

    93     roll = -roll;

    94 

    95     // We need to fix up roll to the (-180,180] range required.

    96     // Check for negative theta values and apply an offset as required.

    97     // Note that theta is defined as the angle of the Z axis relative

    98     // to gravity (see referenced document). It's negative when the

    99     // face of the device points downward.

   100     qreal theta = qAtan(sqrt(x*x + y*y) / z) * RADIANS_TO_DEGREES;

   101     if (theta < 0) {

   102         if (roll > 0)

   103             roll = 180 - roll;

   104         else

   105             roll = -180 - roll;

   106     }

   107 

   108     m_reading.setTimestamp(ar->timestamp());

   109     m_reading.setX(pitch);

   110     m_reading.setY(roll);

   111     m_reading.setZ(0);

   112     newReadingAvailable();

   113     return false;

   114 }

   115