Qt Documentation

Qt 5.14
Qt Sensors
C++ Classes
QAccelerometer

QAccelerometer Class

The QAccelerometer class is a convenience wrapper around QSensor. More...

Header:	#include <QAccelerometer>
qmake:	QT += sensors
Since:	Qt 5.1
Inherits:	QSensor

This class was introduced in Qt 5.1.

List of all members, including inherited members

Public Types

enum	AccelerationMode { Combined, Gravity, User }

Properties

accelerationMode : AccelerationMode

Public Functions

	QAccelerometer(QObject *parent = Q_NULLPTR)
virtual	~QAccelerometer()
QAccelerometer::AccelerationMode	accelerationMode() const
QAccelerometerReading *	reading() const
void	setAccelerationMode(QAccelerometer::AccelerationMode accelerationMode)

Signals

void	accelerationModeChanged(QAccelerometer::AccelerationMode accelerationMode)

Detailed Description

The only behavioural difference is that this class sets the type properly.

It also supports changing the acceleration mode, which controls whether the force of gravity is included in the accelerometer values or not.

Furthermore, this class features a reading() function that returns a QAccelerometerReading instead of a QSensorReading.

For details about how the sensor works, see QAccelerometerReading.

See also QAccelerometerReading.

Member Type Documentation

enum QAccelerometer::AccelerationMode

This enum represents the acceleration mode of an acceleration sensor.

The acceleration mode controls how the sensor reports acceleration. QAccelerometer::Combined is the only mode in which the values can be directly physically measured, the others are an approximation.

Constant	Value	Description
`QAccelerometer::Combined`	`0`	Both the acceleration caused by gravity and the acceleration caused by the user moving the device is reported combined.
`QAccelerometer::Gravity`	`1`	Only the acceleration caused by gravity is reported. Movements of the device caused by the user have no effect other than changing the direction when the device is rotated.
`QAccelerometer::User`	`2`	Only the acceleration caused by the user moving the device is reported, the effect of gravity is canceled out. A device at rest therefore should report values of, or close to, zero. In other APIs, this mode might be known as linear acceleration.

This enum was introduced or modified in Qt 5.1.

See also QAccelerometer::accelerationMode.

Property Documentation

accelerationMode : AccelerationMode

This property holds the acceleration mode controls how acceleration values are reported.

The acceleration mode controls how the acceleration sensor reports its values. The default mode is QAccelerometer::Combined, which means the acceleration caused by gravity is included in the reported values.

Acceleration caused by gravity and acceleration caused by the user moving the device are physically impossible to distinguish because of general relativity. Most devices use sensor fusion to figure out which parts of the acceleration is caused by gravity, for example by using a rotation sensor to calculate the gravity direction and assuming a fixed magnitude for gravity. Therefore the result is only an approximation and may be inaccurate. The QAccelerometer::Combined mode is the most accurate one, as it does not involve approximating the gravity.

Not all backends and devices might support setting the acceleration mode. For those cases, the default mode QAccelerometer::Combined is used, changing it has no effect.

This property was introduced in Qt 5.1.

Access functions:

QAccelerometer::AccelerationMode	accelerationMode() const
void	setAccelerationMode(QAccelerometer::AccelerationMode accelerationMode)

Notifier signal:

void	accelerationModeChanged(QAccelerometer::AccelerationMode accelerationMode)

Member Function Documentation

QAccelerometer::QAccelerometer(QObject **parent* = Q_NULLPTR)

Construct the sensor as a child of parent.

`[signal]` void QAccelerometer::accelerationModeChanged(QAccelerometer::AccelerationMode accelerationMode)

Emitted when the accelerationMode was changed.

This function was introduced in Qt 5.1.

Note: Notifier signal for property accelerationMode.

`[virtual]` QAccelerometer::~QAccelerometer()

Destroy the sensor. Stops the sensor if it has not already been stopped.

QAccelerometerReading *QAccelerometer::reading() const

Returns the reading class for this sensor.

See also QSensor::reading().

void QAccelerometer::setAccelerationMode(QAccelerometer::AccelerationMode accelerationMode)

Sets the acceleration mode to accelerationMode.