QSensorReading

Qt 5.9.0 Reference Documentation

QSensorReading Class

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

头文件:	#include <QSensorReading>
qmake:	QT += sensors
基类:	QObject
派生类:	QAccelerometerReading, QAltimeterReading, QAmbientLightReading, QAmbientTemperatureReading, QCompassReading, QDistanceReading, QGyroscopeReading, QHolsterReading, QHumidityReading, QIRProximityReading, QLidReading, QLightReading, QMagnetometerReading, QOrientationReading, QPressureReading, QProximityReading, QRotationReading, QTapReading, and QTiltReading

所有的成员列表, 包括继承的成员

属性

timestamp : const quint64

1 个属性继承自 QObject

公有函数

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

32 个公有函数继承自 QObject

Macros

	DECLARE_READING(classname)
	IMPLEMENT_READING(classname)

其他继承的成员

1 个公有槽函数继承自 QObject
2 个信号继承自 QObject
1 个公有变量继承自 QObject
10 个静态公有成员继承自 QObject
9 个受保护的函数继承自 QObject
2 个受保护的变量继承自 QObject

详细描述

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.

属性

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.

访问函数:

quint64 timestamp() const

成员函数

void QSensorReading::setTimestamp(quint64 timestamp)

Sets the timestamp of the reading.

参见 timestamp().

quint64 QSensorReading::timestamp() const

Returns the timestamp of the reading.

Note: Getter function for property timestamp.

参见 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.

参见 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.

宏

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);
  };

参见 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)

参见 DECLARE_READING().

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