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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "iosmotionmanager.h"
#include "iosmagnetometer.h"
#import <CoreMotion/CoreMotion.h>
QT_BEGIN_NAMESPACE
char const * const IOSMagnetometer::id("ios.magnetometer");
int IOSMagnetometer::s_magnetometerStartCount = 0;
int IOSMagnetometer::s_deviceMotionStartCount = 0;
IOSMagnetometer::IOSMagnetometer(QSensor *sensor)
: QSensorBackend(sensor)
, m_motionManager([QIOSMotionManager sharedManager])
, m_timer(0)
, m_returnGeoValues(true)
{
setReading<QMagnetometerReading>(&m_reading);
// Technical information about data rate is not found, but
// seems to be ~70Hz after testing on iPad4:
addDataRate(1, 70);
// Output range is +/- 2 gauss (0.0002 tesla) and can sense magnetic fields less than
// 100 microgauss (1e-08 tesla) Ref: "iOS Sensor Programming", Alasdair, 2012.
addOutputRange(-0.0002, 0.0002, 1e-08);
}
void IOSMagnetometer::start()
{
if (m_timer != 0)
return;
int hz = sensor()->dataRate();
m_timer = startTimer(1000 / (hz == 0 ? 60 : hz));
m_returnGeoValues = static_cast<QMagnetometer *>(sensor())->returnGeoValues();
if (m_returnGeoValues) {
if (++s_deviceMotionStartCount == 1)
[m_motionManager startDeviceMotionUpdatesUsingReferenceFrame:CMAttitudeReferenceFrameXMagneticNorthZVertical];
} else {
if (++s_magnetometerStartCount == 1)
[m_motionManager startMagnetometerUpdates];
}
}
void IOSMagnetometer::stop()
{
if (m_timer == 0)
return;
killTimer(m_timer);
m_timer = 0;
if (m_returnGeoValues) {
if (--s_deviceMotionStartCount == 0)
[m_motionManager stopDeviceMotionUpdates];
} else {
if (--s_magnetometerStartCount == 0)
[m_motionManager stopMagnetometerUpdates];
}
}
void IOSMagnetometer::timerEvent(QTimerEvent *)
{
CMMagneticField field;
if (m_returnGeoValues) {
CMDeviceMotion *deviceMotion = m_motionManager.deviceMotion;
CMCalibratedMagneticField calibratedField = deviceMotion.magneticField;
field = calibratedField.field;
// skip update if NaN
if (field.x != field.x || field.y != field.y || field.z != field.z)
return;
m_reading.setTimestamp(quint64(deviceMotion.timestamp * 1e6));
switch (calibratedField.accuracy) {
case CMMagneticFieldCalibrationAccuracyUncalibrated:
m_reading.setCalibrationLevel(0.0);
break;
case CMMagneticFieldCalibrationAccuracyLow:
m_reading.setCalibrationLevel(0.3);
break;
case CMMagneticFieldCalibrationAccuracyMedium:
m_reading.setCalibrationLevel(0.6);
break;
case CMMagneticFieldCalibrationAccuracyHigh:
m_reading.setCalibrationLevel(1.0);
break;
}
} else {
CMMagnetometerData *data = m_motionManager.magnetometerData;
field = data.magneticField;
// skip update if NaN
if (field.x != field.x || field.y != field.y || field.z != field.z)
return;
m_reading.setTimestamp(quint64(data.timestamp * 1e6));
m_reading.setCalibrationLevel(1.0);
}
// Convert NSTimeInterval to microseconds and microtesla to tesla:
m_reading.setX(qreal(field.x) / 1e6);
m_reading.setY(qreal(field.y) / 1e6);
m_reading.setZ(qreal(field.z) / 1e6);
newReadingAvailable();
}
QT_END_NAMESPACE
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