QSensorReading

Qt 5.7.1 Reference Documentation

QSensorReading Class

The QSensorReading class holds the readings from the sensor. More...

Header:	#include <QSensorReading>
qmake:	QT += sensors
Inherits:	QObject
Inherited By:	QAccelerometerReading, QAltimeterReading, QAmbientLightReading, QAmbientTemperatureReading, QCompassReading, QDistanceReading, QGyroscopeReading, QHolsterReading, QIRProximityReading, QLightReading, QMagnetometerReading, QOrientationReading, QPressureReading, QProximityReading, QRotationReading, QTapReading, and QTiltReading

List of all members, including inherited members

Properties

timestamp : const quint64

1 property inherited from QObject

Public Functions

void	setTimestamp(quint64 timestamp)
quint64	timestamp() const
QVariant	value(int index) const
int	valueCount() const

31 public functions inherited from QObject

Macros

	DECLARE_READING(classname)
	IMPLEMENT_READING(classname)

Additional Inherited Members

1 public slot inherited from QObject
2 signals inherited from QObject
1 public variable inherited from QObject
10 static public members inherited from QObject
9 protected functions inherited from QObject
2 protected variables inherited from QObject

Detailed Description

The QSensorReading class holds the readings from the sensor.

Note that QSensorReading is not particularly useful by itself. The interesting data for each sensor is defined in a sub-class of QSensorReading.

Property Documentation

timestamp : const quint64

This property holds the timestamp of the reading.

Timestamps values are microseconds since a fixed point. You can use timestamps to see how far apart two sensor readings are.

Note that sensor timestamps from different sensors may not be directly comparable (as they may choose different fixed points for their reference).

Note that some platforms do not deliver timestamps correctly. Applications should be prepared for occasional issues that cause timestamps to jump backwards.

Access functions:

quint64 timestamp() const

Member Function Documentation

void QSensorReading::setTimestamp(quint64 timestamp)

Sets the timestamp of the reading.

See also timestamp().

quint64 QSensorReading::timestamp() const

Returns the timestamp of the reading.

Note: Getter function for property timestamp.

See also setTimestamp().

QVariant QSensorReading::value(int index) const

Returns the value of the property at index.

Note that this function is slower than calling the data function directly.

Here is an example of getting a property via the different mechanisms available.

Accessing directly provides the best performance but requires compile-time knowledge of the data you are accessing.


  QAccelerometerReading *reading = ...;
  qreal x = reading->x();

You can also access a property by name. To do this you must call QObject::property().


  qreal x = reading->property("x").value<qreal>();

Finally, you can access values via numeric index.


  qreal x = reading->value(0).value<qreal>();

Note that value() can only access properties declared with Q_PROPERTY() in sub-classes of QSensorReading.

See also valueCount() and QObject::property().

int QSensorReading::valueCount() const

Returns the number of extra properties that the reading has.

Note that this does not count properties declared in QSensorReading.

As an example, this returns 3 for QAccelerometerReading because there are 3 properties defined in that class.

Macro Documentation

DECLARE_READING(classname)

The DECLARE_READING macro adds some required methods to a reading class.

This macro should be used for all reading classes. Pass the classname of your reading class.


  class MyReading : public QSensorReading
  {
      Q_OBJECT
      Q_PROPERTY(qreal myprop READ myprop)
      DECLARE_READING(MyReading)
  public:
      qreal myprop() const;
      vod setMyprop(qreal myprop);
  };

See also IMPLEMENT_READING().

IMPLEMENT_READING(classname)

The IMPLEMENT_READING macro implements the required methods for a reading class.

This macro should be used for all reading classes. It should be placed into a single compilation unit (source file), not into a header file. Pass the classname of your reading class.


  IMPLEMENT_READING(MyReading)

See also DECLARE_READING().

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