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39
40#include "genericrotationsensor.h"
41#include <QDebug>
42#include <qmath.h>
43
44char const * const genericrotationsensor::id("generic.rotation");
45
46genericrotationsensor::genericrotationsensor(QSensor *sensor)
47 : QSensorBackend(sensor)
48{
49 accelerometer = new QAccelerometer(this);
50 accelerometer->addFilter(filter: this);
51 accelerometer->connectToBackend();
52
53 setReading<QRotationReading>(&m_reading);
54 setDataRates(accelerometer);
55
56 QRotationSensor * const rotationSensor = qobject_cast<QRotationSensor *>(object: sensor);
57 if (rotationSensor)
58 rotationSensor->setHasZ(false);
59}
60
61void genericrotationsensor::start()
62{
63 accelerometer->setDataRate(sensor()->dataRate());
64 accelerometer->setAlwaysOn(sensor()->isAlwaysOn());
65 accelerometer->start();
66 if (!accelerometer->isActive())
67 sensorStopped();
68 if (accelerometer->isBusy())
69 sensorBusy();
70}
71
72void genericrotationsensor::stop()
73{
74 accelerometer->stop();
75}
76
77bool genericrotationsensor::filter(QSensorReading *reading)
78{
79 QAccelerometerReading *ar = qobject_cast<QAccelerometerReading*>(object: reading);
80 qreal pitch = 0;
81 qreal roll = 0;
82
83 qreal x = ar->x();
84 qreal y = ar->y();
85 qreal z = ar->z();
86
87 // Note that the formula used come from this document:
88 // http://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf
89 pitch = qRadiansToDegrees(radians: qAtan(v: y / qSqrt(v: x * x + z * z)));
90 roll = qRadiansToDegrees(radians: qAtan(v: x / qSqrt(v: y * y + z * z)));
91 // Roll is a left-handed rotation but we need right-handed rotation
92 roll = -roll;
93
94 // We need to fix up roll to the (-180,180] range required.
95 // Check for negative theta values and apply an offset as required.
96 // Note that theta is defined as the angle of the Z axis relative
97 // to gravity (see referenced document). It's negative when the
98 // face of the device points downward.
99 qreal theta = qRadiansToDegrees(radians: qAtan(v: qSqrt(v: x * x + y * y) / z));
100 if (theta < 0) {
101 if (roll > 0)
102 roll = 180 - roll;
103 else
104 roll = -180 - roll;
105 }
106
107 m_reading.setTimestamp(ar->timestamp());
108 m_reading.setFromEuler(x: pitch, y: roll, z: 0);
109 newReadingAvailable();
110 return false;
111}
112
113

source code of qtsensors/src/plugins/sensors/generic/genericrotationsensor.cpp