QSensorBackend

#include <QtSensors/QSensorBackend>

QtSensors

Since:

1.0

The QSensorBackend class is a sensor implementation.

Sensors on a device will be represented by sub-classes of QSensorBackend.

Public Functions Index

QSensorBackend (QSensor *sensor)
virtual ~QSensorBackend ()
voidstart ()=0
voidstop ()=0
voidaddDataRate (qreal min, qreal max)
voidsetDataRates (const QSensor *otherSensor)
voidaddOutputRange (qreal min, qreal max, qreal accuracy)
voidsetDescription (const QString &description)
T *setReading (T *reading)
QSensorReading *reading () const
QSensor *sensor () const
voidnewReadingAvailable ()
voidsensorStopped ()
voidsensorBusy ()
voidsensorError (int error)

Public Functions

QSensorBackend (

virtual~QSensorBackend ()

Destructor.

void start ()

Start reporting values.

Since:

1.0

void stop ()

Stop reporting values.

Since:

1.0

void addDataRate (
  • qrealmin,
  • qrealmax )

Add a data rate (consisting of min and max values) for the sensor.

Note that this function should be called from the constructor so that the information is available immediately.

See:

QSensor::availableDataRates

Since:

1.0

void setDataRates (

Set the data rates for the sensor based on otherSensor.

This is designed for sensors that are based on other sensors.

setDataRates(otherSensor);

Note that this function should be called from the constructor so that the information is available immediately.

See:

QSensor::availableDataRates, addDataRate()

Since:

1.0

void addOutputRange (
  • qrealmin,
  • qrealmax,
  • qrealaccuracy )

Add an output range (consisting of min, max values and accuracy) for the sensor.

Note that this function should be called from the constructor so that the information is available immediately.

See:

QSensor::outputRange, QSensor::outputRanges

Since:

1.0

void setDescription (

Set the description for the sensor.

Note that this function should be called from the constructor so that the information is available immediately.
Since:

1.0

T * setReading (
  • typename T,
  • T *reading )

This function is called to initialize the reading classes used for a sensor.

If your backend has already allocated a reading you should pass the address of this to the function. Otherwise you should pass 0 and the function will return the address of the reading your backend should use when it wants to notify the sensor API of new readings.

Note that this is a template function so it should be called with the appropriate type.

class MyBackend : public QSensorBackend
{
    QAccelerometerReading m_reading;
public:
    MyBackend(QSensor *sensor)
        : QSensorBackend(sensor)
    {
        setReading<QAccelerometerReading>(&m_reading);
    }

    ...

Note that this function must be called or you will not be able to send readings to the front end.

If you do not wish to store the address of the reading you may use the reading() method to get it again later.

class MyBackend : public QSensorBackend
{
public:
    MyBackend(QSensor *sensor)
        : QSensorBackend(sensor)
    {
        setReading<QAccelerometerReading>(0);
    }

    void poll()
    {
        qtimestamp timestamp;
        qreal x, y, z;
        ...
        QAccelerometerReading *reading = static_cast<QAccelerometerReading*>(reading());
        reading->setTimestamp(timestamp);
        reading->setX(x);
        reading->setY(y);
        reading->setZ(z);
    }

    ...
See:

reading()

Since:

1.0

QSensorReading * reading ()

If the backend has lost its reference to the reading it can call this method to get the address.

Note that you will need to down-cast to the appropriate type.

See:

setReading()

Since:

1.0

QSensor * sensor ()

Returns the sensor front end associated with this backend.

Since:

1.0

void newReadingAvailable ()

Notify the QSensor class that a new reading is available.

Since:

1.0

void sensorStopped ()

Inform the front end that the sensor has stopped.

This can be due to start() failing or for some unexpected reason (eg. hardware failure).

Note that the front end must call QSensor::isActive() to see if the sensor has stopped. If the sensor has stopped due to an error the sensorError() function should be called to notify the class of the error condition.
Since:

1.0

void sensorBusy ()

Inform the front end that the sensor is busy.

This implicitly calls sensorStopped() and is typically called from start().

Note that the front end must call QSensor::isBusy() to see if the sensor is busy. If the sensor has stopped due to an error the sensorError() function should be called to notify the class of the error condition.
Since:

1.0

void sensorError (
  • interror)

Inform the front end that a sensor error occurred.

Note that this only reports an error code. It does not stop the sensor.

See:

sensorStopped()

Since:

1.0

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