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path: root/src/plugins/sensors/generic/genericrotationsensor.cpp
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/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtSensors module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "genericrotationsensor.h"
#include <QDebug>
#include <qmath.h>

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);

    QRotationSensor * const rotationSensor = qobject_cast<QRotationSensor *>(sensor);
    if (rotationSensor)
        rotationSensor->setHasZ(false);
}

void genericrotationsensor::start()
{
    accelerometer->setDataRate(sensor()->dataRate());
    accelerometer->setAlwaysOn(sensor()->isAlwaysOn());
    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 = qRadiansToDegrees(qAtan(y / qSqrt(x * x + z * z)));
    roll  = qRadiansToDegrees(qAtan(x / qSqrt(y * y + z * z)));
    // 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 = qRadiansToDegrees(qAtan(qSqrt(x * x + y * y) / z));
    if (theta < 0) {
        if (roll > 0)
            roll = 180 - roll;
        else
            roll = -180 - roll;
    }

    m_reading.setTimestamp(ar->timestamp());
    m_reading.setFromEuler(pitch, roll, 0);
    newReadingAvailable();
    return false;
}