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#include "genericrotationsensor.h"

#include <QDebug>

#include <qmath.h>

#define RADIANS_TO_DEGREES 57.2957795

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

genericrotationsensor::genericrotationsensor(QSensor *sensor)

    : QSensorBackend(sensor)

{

    accelerometer = new QAccelerometer(this);

    accelerometer->addFilter(this);

    accelerometer->connectToBackend();

    setReading<QRotationReading>(&m_reading);

    setDataRates(accelerometer);

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

}

void genericrotationsensor::start()

{

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

    accelerometer->start();

    if (!accelerometer->isActive())

        sensorStopped();

    if (accelerometer->isBusy())

        sensorBusy();

}

void genericrotationsensor::stop()

{

    accelerometer->stop();

}

bool genericrotationsensor::filter(QSensorReading *reading)

{

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

    qreal pitch = 0;

    qreal roll = 0;

    qreal x = ar->x();

    qreal y = ar->y();

    qreal z = ar->z();

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

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

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

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

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

    roll = -roll;

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

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

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

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

    // face of the device points downward.

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

    if (theta < 0) {

        if (roll > 0)

            roll = 180 - roll;

        else

            roll = -180 - roll;

    }

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

    m_reading.setX(pitch);

    m_reading.setY(roll);

    m_reading.setZ(0);

    newReadingAvailable();

    return false;

}