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These rights are described in the Digia Qt LGPL Exception ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. ** ** $QT_END_LICENSE$ ** ****************************************************************************/ #include "qsensor.h" #include "qsensor_p.h" #include "qsensorbackend.h" #include "qsensormanager.h" #include #include #include QT_BEGIN_NAMESPACE /*! \typedef qrange \relates QSensor \since 5.1 This type is defined as a QPair. \code typedef QPair qrange; \endcode \sa QPair, qrangelist, QSensor::availableDataRates */ /*! \typedef qrangelist \relates QSensor \since 5.1 This type is defined as a list of qrange values. \code typedef QList qrangelist; \endcode \sa QList, qrange, QSensor::availableDataRates */ /*! \class qoutputrange \relates QSensor \inmodule QtSensors \brief The qoutputrange class holds the specifics of an output range. \since 5.1 The class is defined as a simple struct. \code struct qoutputrange { qreal maximum; qreal minimum; qreal accuracy; }; \endcode Each output range specifies a minimum and maximum value as well as an accuracy value. The accuracy value represents the resolution of the sensor. It is the smallest change the sensor can detect and is expressed using the same units as the minimum and maximum. Sensors must often trade off range for accuracy. To allow the user to determine which of these are more important the sensor may offer several output ranges. One output range may have reduced minimum and maximum values and increased sensitivity. Another output range may have higher minimum and maximum values with reduced sensitivity. Note that higher sensitivities will be represented by smaller accuracy values. An example of this tradeoff can be seen by examining the LIS302DL accelerometer. It has only 256 possible values to report with. These values are scaled so that they can represent either -2G to +2G (with an accuracy value of 0.015G) or -8G to +8G (with an accuracy value of 0.06G). \sa qoutputrangelist, QSensor::outputRanges */ /*! \variable qoutputrange::maximum This is the maximum value for this output range. The units are defined by the sensor. */ /*! \variable qoutputrange::minimum This is the minimum value for this output range. The units are defined by the sensor. */ /*! \variable qoutputrange::accuracy The accuracy value represents the resolution of the sensor. It is the smallest change the sensor can detect and is expressed using the same units as the minimum and maximum. */ /*! \typedef qoutputrangelist \relates QSensor \since 5.1 This type is defined as a list of qoutputrange values. \code typedef QList qoutputrangelist; \endcode \sa QList, qoutputrange, QSensor::outputRanges */ static void registerTypes() { qRegisterMetaType("qrange"); qRegisterMetaType("qrangelist"); qRegisterMetaType("qoutputrangelist"); } Q_CONSTRUCTOR_FUNCTION(registerTypes) // ===================================================================== void QSensorPrivate::init(const QByteArray &sensorType) { Q_Q(QSensor); type = sensorType; q->registerInstance(); // so the availableSensorsChanged() signal works } /*! \class QSensor \ingroup sensors_main \inmodule QtSensors \since 5.1 \brief The QSensor class represents a single hardware sensor. The life cycle of a sensor is typically: \list \li Create a sub-class of QSensor on the stack or heap. \li Setup as required by the application. \li Start receiving values. \li Sensor data is used by the application. \li Stop receiving values. \endlist The sensor data is delivered via QSensorReading and its sub-classes. \section1 Orientation Some sensors react to screen orientation changes, such as QAccelerometer, QMagnetometer and QRotationSensor. These are so called \e orientable sensors. For orientable sensors, QSensor supports changing the reporting of the reading values based on the orientation of the screen. For orientable sensors, the axesOrientationMode property controls how the orientation affects the reading values. In the default mode, QSensor::FixedOrientation, the reading values remain unaffected by the orientation. In the QSensor::AutomaticOrientation mode, the reading values are automatically rotated by taking the current screen orientation into account. And finally, in the QSensor::UserOrientation mode, the reading values are rotated according to a user-specified orientation. The functionality of this is only available if it is supported by the backend and if the sensor is orientable, which can be checked by calling QSensor::isFeatureSupported() with the QSensor::AxesOrientation flag. The orientation values here are always of the screen orientation, not the device orientation. The screen orientation is the orientation of the GUI. For example when rotating a device by 90 degrees counter-clockwise, the screen orientation compensates for that by rotating 90 degrees clockwise, to the effect that the GUI is still facing upright after the device has been rotated. Note that applications can lock the screen orientation, for example to force portrait or landscape mode. For locked orientations, orientable sensors will not react with reading changes if the device orientation is changed, as orientable sensors react to screen orientation changes only. This makes sense, as the purpose of orientable sensors is to keep the sensor orientation in sync with the screen orientation. The orientation values range from 0 to 270 degrees. The orientation is applied in clockwise direction, e.g. an orientation value of 90 degrees means that the screen has been rotated 90 degress to the right from its origin position, to compensate a device rotation of 90 degrees to the left. \sa QSensorReading */ /*! \enum QSensor::Feature \brief Lists optional features a backend might support. The features common to all sensor types are: \value Buffering The backend supports buffering of readings, controlled by the QSensor::bufferSize property. \value AlwaysOn The backend supports changing the policy on whether to suspend when idle, controlled by the QSensor::alwaysOn property. \value SkipDuplicates The backend supports skipping of same or very similar successive readings. This can be enabled by setting the QSensor::skipDuplicates property to true. The features of QMagnetometer are: \value GeoValues The backend supports returning geo values, which can be controlled with the QMagnetometer::returnGeoValues property. The features of QLightSensor are: \value FieldOfView The backend specifies its field of view, which can be read from the QLightSensor::fieldOfView property. The features of QAccelerometer are: \value AccelerationMode The backend supports switching the acceleration mode of the acceleromter with the QAccelerometer::accelerationMode property. The features of QPressureSensor are: \value PressureSensorTemperature The backend provides the pressure sensor's die temperature The features of all orientable sensors are: \value AxesOrientation The backend supports changing the axes orientation from the default of QSensor::FixedOrientation to something else. \omitvalue Reserved \sa QSensor::isFeatureSupported() \since 5.0 */ /*! Construct the \a type sensor as a child of \a parent. Do not use this constructor if a derived class exists for the specific sensor type. The wrong way is to use the base class constructor: \snippet sensors/creating.cpp 3 The right way is to create an instance of the derived class: \snippet sensors/creating.cpp 2 The derived classes have additional properties and data members which are needed for certain features such as geo value support in QMagnetometer or acceleration mode support in QAccelerometer. These features will only work properly when creating a sensor instance from a QSensor subclass. Only use this constructor if there is no derived sensor class available. Note that all built-in sensors have a derived class, so using this constructor should only be necessary when implementing custom sensors, like in the \l {Qt Sensors - Grue Sensor Example}{Grue sensor example}. */ QSensor::QSensor(const QByteArray &type, QObject *parent) : QObject(*new QSensorPrivate, parent) { Q_D(QSensor); d->init(type); } /*! \internal */ QSensor::QSensor(const QByteArray &type, QSensorPrivate &dd, QObject* parent) : QObject(dd, parent) { Q_D(QSensor); d->init(type); } /*! \internal */ QSensorBackend *QSensor::backend() const { Q_D(const QSensor); return d->backend; } /*! Destroy the sensor. Stops the sensor if it has not already been stopped. */ QSensor::~QSensor() { Q_D(QSensor); stop(); Q_FOREACH (QSensorFilter *filter, d->filters) filter->setSensor(0); delete d->backend; d->backend = 0; // owned by the backend d->device_reading = 0; d->filter_reading = 0; d->cache_reading = 0; } /*! \property QSensor::connectedToBackend \brief a value indicating if the sensor has connected to a backend. A sensor that has not been connected to a backend cannot do anything useful. Call the connectToBackend() method to force the sensor to connect to a backend immediately. This is automatically called if you call start() so you only need to do this if you need access to sensor properties (ie. to poll the sensor's meta-data before you use it). */ bool QSensor::isConnectedToBackend() const { Q_D(const QSensor); return (d->backend != 0); } /*! \property QSensor::identifier \brief the backend identifier for the sensor. Note that the identifier is filled out automatically when the sensor is connected to a backend. If you want to connect a specific backend, you should call setIdentifier() before connectToBackend(). */ QByteArray QSensor::identifier() const { Q_D(const QSensor); return d->identifier; } void QSensor::setIdentifier(const QByteArray &identifier) { Q_D(QSensor); if (isConnectedToBackend()) { qWarning() << "ERROR: Cannot call QSensor::setIdentifier while connected to a backend!"; return; } d->identifier = identifier; } /*! \property QSensor::type \brief the type of the sensor. */ QByteArray QSensor::type() const { Q_D(const QSensor); return d->type; } /*! Try to connect to a sensor backend. Returns true if a suitable backend could be found, false otherwise. The type must be set before calling this method if you are using QSensor directly. \sa isConnectedToBackend() */ bool QSensor::connectToBackend() { Q_D(QSensor); if (isConnectedToBackend()) return true; int dataRate = d->dataRate; int outputRange = d->outputRange; d->backend = QSensorManager::createBackend(this); if (d->backend) { // Reset the properties to their default values and re-set them now so // that the logic we've put into the setters gets called. if (dataRate != 0) { d->dataRate = 0; setDataRate(dataRate); } if (outputRange != -1) { d->outputRange = -1; setOutputRange(outputRange); } } return isConnectedToBackend(); } /*! \property QSensor::busy \brief a value to indicate if the sensor is busy. Some sensors may be on the system but unavailable for use. This function will return true if the sensor is busy. You will not be able to start() the sensor. Note that this function does not return true if you are using the sensor, only if another process is using the sensor. \sa busyChanged() */ bool QSensor::isBusy() const { Q_D(const QSensor); return d->busy; } /*! \fn QSensor::busyChanged() This signal is emitted when the sensor is no longer busy. This can be used to grab a sensor when it becomes available. \code sensor.start(); if (sensor.isBusy()) { // need to wait for busyChanged signal and try again } \endcode */ /*! \property QSensor::active \brief a value to indicate if the sensor is active. This is true if the sensor is active (returning values). This is false otherwise. Note that setting this value to true will not have an immediate effect. Instead, the sensor will be started once the event loop has been reached. */ void QSensor::setActive(bool active) { if (active == isActive()) return; if (active) QTimer::singleShot(0, this, SLOT(start())); // delay ensures all properties have been set if using QML else stop(); } bool QSensor::isActive() const { Q_D(const QSensor); return d->active; } /*! \property QSensor::alwaysOn \brief a value to indicate if the sensor should remain running when the screen is off. Some platforms have a policy of suspending sensors when the screen turns off. Setting this property to true will ensure the sensor continues to run. */ /*! \fn QSensor::alwaysOnChanged() This signal is emitted when the alwaysOn property changes. */ void QSensor::setAlwaysOn(bool alwaysOn) { Q_D(QSensor); if (d->alwaysOn == alwaysOn) return; d->alwaysOn = alwaysOn; emit alwaysOnChanged(); } bool QSensor::isAlwaysOn() const { Q_D(const QSensor); return d->alwaysOn; } /*! \property QSensor::skipDuplicates \brief Indicates whether duplicate reading values should be omitted. \since 5.1 When duplicate skipping is enabled, successive readings with the same or very similar values are omitted. This helps reducing the amount of processing done, as less sensor readings are made available. As a consequence, readings arrive at an irregular interval. Duplicate skipping is not just enabled for readings that are exactly the same, but also for readings that are quite similar, as each sensor has a bit of jitter even if the device is not moved. Support for this property depends on the backend. Use isFeatureSupported() to check if it is supported on the current platform. Duplicate skipping is disabled by default. Duplicate skipping takes effect when the sensor is started, changing the property while the sensor is active has no immediate effect. */ bool QSensor::skipDuplicates() const { Q_D(const QSensor); return d->skipDuplicates; } /*! Sets the duplicate skipping to \a skipDuplicates. \since 5.1 */ void QSensor::setSkipDuplicates(bool skipDuplicates) { Q_D(QSensor); if (d->skipDuplicates != skipDuplicates) { d->skipDuplicates = skipDuplicates; emit skipDuplicatesChanged(skipDuplicates); } } /*! \fn QSensor::skipDuplicatesChanged(bool skipDuplicates) \since 5.1 This signal is emitted when the skipDuplicates property changes. */ /*! \property QSensor::availableDataRates \brief the data rates that the sensor supports. This is a list of the data rates that the sensor supports. Measured in Hertz. Entries in the list can represent discrete rates or a continuous range of rates. A discrete rate is noted by having both values the same. See the sensor_explorer example for an example of how to interpret and use this information. Note that this information is not mandatory as not all sensors have a rate at which they run. In such cases, the list will be empty. \sa QSensor::dataRate, qrangelist */ qrangelist QSensor::availableDataRates() const { Q_D(const QSensor); return d->availableDataRates; } /*! \property QSensor::dataRate \brief the data rate that the sensor should be run at. Measured in Hertz. The data rate is the maximum frequency at which the sensor can detect changes. Setting this property is not portable and can cause conflicts with other applications. Check with the sensor backend and platform documentation for any policy regarding multiple applications requesting a data rate. The default value (0) means that the app does not care what the data rate is. Applications should consider using a timer-based poll of the current value or ensure that the code that processes values can run very quickly as the platform may provide updates hundreds of times each second. This should be set before calling start() because the sensor may not notice changes to this value while it is running. Note that there is no mechanism to determine the current data rate in use by the platform. \sa QSensor::availableDataRates */ int QSensor::dataRate() const { Q_D(const QSensor); return d->dataRate; } void QSensor::setDataRate(int rate) { Q_D(QSensor); if (d->dataRate != rate) { d->dataRate = rate; emit dataRateChanged(); } } /*! Checks if a specific feature is supported by the backend. QtSensors supports a rich API for controlling and providing information about sensors. Naturally, not all of this functionality can be supported by all of the backends. To check if the current backend supports the feature \a feature, call this function. The backend needs to be connected, otherwise false will be returned. Calling connectToBackend() or start() will create a connection to the backend. Backends have to implement QSensorBackend::isFeatureSupported() to make this work. Returns whether or not the feature is supported if the backend is connected, or false if the backend is not connected. \since 5.0 */ bool QSensor::isFeatureSupported(Feature feature) const { Q_D(const QSensor); return d->backend && d->backend->isFeatureSupported(feature); } /*! Start retrieving values from the sensor. Returns true if the sensor was started, false otherwise. The sensor may fail to start for several reasons. Once an application has started a sensor it must wait until the sensor receives a new value before it can query the sensor's values. This is due to how the sensor receives values from the system. Sensors do not (in general) poll for new values, rather new values are pushed to the sensors as they happen. For example, this code will not work as intended. \badcode sensor->start(); sensor->reading()->x(); // no data available \endcode To work correctly, the code that accesses the reading should ensure the readingChanged() signal has been emitted. \code connect(sensor, SIGNAL(readingChanged()), this, SLOT(checkReading())); sensor->start(); } void MyClass::checkReading() { sensor->reading()->x(); \endcode \sa QSensor::busy */ bool QSensor::start() { Q_D(QSensor); if (isActive()) return true; if (!connectToBackend()) return false; // Set these flags to their defaults d->active = true; d->busy = false; // Backend will update the flags appropriately d->backend->start(); Q_EMIT activeChanged(); return isActive(); } /*! Stop retrieving values from the sensor. This releases the sensor so that other processes can use it. \sa QSensor::busy */ void QSensor::stop() { Q_D(QSensor); if (!isConnectedToBackend() || !isActive()) return; d->active = false; d->backend->stop(); Q_EMIT activeChanged(); } /*! \property QSensor::reading \brief the reading class. The reading class provides access to sensor readings. The reading object is a volatile cache of the most recent sensor reading that has been received so the application should process readings immediately or save the values somewhere for later processing. Note that this will return 0 until a sensor backend is connected to a backend. Also note that readings are not immediately available after start() is called. Applications must wait for the readingChanged() signal to be emitted. \sa isConnectedToBackend(), start() */ QSensorReading *QSensor::reading() const { Q_D(const QSensor); return d->cache_reading; } /*! Add a \a filter to the sensor. The sensor does not take ownership of the filter. QSensorFilter will inform the sensor if it is destroyed. \sa QSensorFilter */ void QSensor::addFilter(QSensorFilter *filter) { Q_D(QSensor); if (!filter) { qWarning() << "addFilter: passed a null filter!"; return; } filter->setSensor(this); d->filters << filter; } /*! Remove \a filter from the sensor. \sa QSensorFilter */ void QSensor::removeFilter(QSensorFilter *filter) { Q_D(QSensor); if (!filter) { qWarning() << "removeFilter: passed a null filter!"; return; } d->filters.removeOne(filter); filter->setSensor(0); } /*! Returns the filters currently attached to the sensor. \sa QSensorFilter */ QList QSensor::filters() const { Q_D(const QSensor); return d->filters; } /*! \fn QSensor::readingChanged() This signal is emitted when a new sensor reading is received. The sensor reading can be found in the QSensor::reading property. Note that the reading object is a volatile cache of the most recent sensor reading that has been received so the application should process the reading immediately or save the values somewhere for later processing. Before this signal has been emitted for the first time, the reading object will have uninitialized data. \sa start() */ /*! \fn QSensor::activeChanged() This signal is emitted when the QSensor::active property has changed. \sa QSensor::active */ /*! \property QSensor::outputRanges \brief a list of output ranges the sensor supports. A sensor may have more than one output range. Typically this is done to give a greater measurement range at the cost of lowering accuracy. Note that this information is not mandatory. This information is typically only available for sensors that have selectable output ranges (such as typical accelerometers). \sa QSensor::outputRange, qoutputrangelist */ qoutputrangelist QSensor::outputRanges() const { Q_D(const QSensor); return d->outputRanges; } /*! \property QSensor::outputRange \brief the output range in use by the sensor. This value represents the index in the QSensor::outputRanges list to use. Setting this property is not portable and can cause conflicts with other applications. Check with the sensor backend and platform documentation for any policy regarding multiple applications requesting an output range. The default value (-1) means that the app does not care what the output range is. Note that there is no mechanism to determine the current output range in use by the platform. \sa QSensor::outputRanges */ int QSensor::outputRange() const { Q_D(const QSensor); return d->outputRange; } void QSensor::setOutputRange(int index) { Q_D(QSensor); if (index == -1 || !isConnectedToBackend()) { d->outputRange = index; return; } bool warn = true; if (index >= 0 && index < d->outputRanges.count()) { warn = false; d->outputRange = index; } if (warn) { qWarning() << "setOutputRange:" << index << "is not supported by the sensor."; } } /*! \property QSensor::description \brief a descriptive string for the sensor. */ QString QSensor::description() const { Q_D(const QSensor); return d->description; } /*! \property QSensor::error \brief the last error code set on the sensor. Note that error codes are sensor-specific. */ int QSensor::error() const { Q_D(const QSensor); return d->error; } /*! \enum QSensor::AxesOrientationMode \since 5.1 Describes how reading values are affected by the screen orientation. \value FixedOrientation No automatic rotation is applied to the reading values. \value AutomaticOrientation The reading values are automatically rotated based on the screen orientation. \value UserOrientation The reading values are rotated based on the angle of the userOrientation property. \sa QSensor::axesOrientationMode */ /*! \property QSensor::axesOrientationMode \since 5.1 \brief The mode that affects how the screen orientation changes reading values. When set to FixedOrientation, which is the default mode, no automatic rotation is applied to the reading. This is the only mode available for backends that do not support the QSensor::AxesOrientation feature. When set to AutomaticOrientation, the reading values are automatically rotated when the screen orientation changes. In effect, the screen orientation is canceled out. As an example, assume the device is rotated by 180 degrees and therefore the screen orientation also is rotated by 180 degrees from the native orientation. Without automatic axes orientation, the reading values would now be changed: Both the X and the Y values would be negated, forcing an application developer to manually cancel out the negation in application code. Automatic axes orientation does this automatically, in this mode the X and Y values would be the same as with the default screen orientation. This automatic rotation of the axes is handy is some usecases, for example in a bubble level application that measures how level a surface is by looking at the X axis value of an accelerometer. When the device and screen orientation change by 90 degrees, an application developer does not need to change anything, he can continue using the X axis value even though the device is rotated. Without automatic axes orientation, the application developer would need to look at the Y values instead, thereby adding code to the application that reads from a different axis depending on the screen orientation. The UserOrientation mode is quite similar to AutomaticOrientation, only that the screen orientation is manually controlled instead of automatically determined. The angle of the userOrientation property is then used for rotating the reading values. Since the rotation of the reading values is based on the screen orientation, Z values will never change, as the Z axis is perpendicular to the screen. As screen orientation changes in 90 degree steps, rotating the reading values is also done in steps of 90 degrees. This property is only used for orientable sensors. */ QSensor::AxesOrientationMode QSensor::axesOrientationMode() const { Q_D(const QSensor); return d->axesOrientationMode; } void QSensor::setAxesOrientationMode(QSensor::AxesOrientationMode axesOrientationMode) { Q_D(QSensor); if (d->axesOrientationMode != axesOrientationMode) { d->axesOrientationMode = axesOrientationMode; emit axesOrientationModeChanged(axesOrientationMode); } } /*! \property QSensor::currentOrientation \since 5.1 \brief The current orientation that is used for rotating the reading values. This might not be the same as the screen orientation. For example, in the FixedOrientation mode, the reading values are not rotated, and therefore the property is 0. In the UserOrientation mode, the readings are rotated based on the userOrientation property, and therefore this property is equal to the userOrientation property. In the AutomaticOrientation mode, the readings are rotated based on the screen orientation, and therefore this property will be equal to the current screen orientation. This property is set by the backend and only valid for orientable sensors. */ int QSensor::currentOrientation() const { Q_D(const QSensor); return d->currentOrientation; } /*! \since 5.1 Sets the current screen orientation to \a currentOrientation. This is to be called from the backend whenever the screen orientation or the userOrientation property changes. */ void QSensor::setCurrentOrientation(int currentOrientation) { Q_D(QSensor); if (d->currentOrientation != currentOrientation) { d->currentOrientation = currentOrientation; emit currentOrientationChanged(currentOrientation); } } /*! \property QSensor::userOrientation \since 5.1 \brief The angle used for rotating the reading values in the UserOrientation mode. When the axesOrientationMode property is set to UserOrientation, the angle for rotating the reading values is taken from this property. In other modes, the property has no effect. The default is 0. The only valid values are 0, 90, 180 and 270, as those are the only possible screen orientations. This property is only valid for orientable sensors. */ int QSensor::userOrientation() const { Q_D(const QSensor); return d->userOrientation; } void QSensor::setUserOrientation(int userOrientation) { Q_D(QSensor); if (d->userOrientation != userOrientation) { d->userOrientation = userOrientation; emit userOrientationChanged(userOrientation); } } /*! \fn QSensor::sensorError(int error) This signal is emitted when an \a error code is set on the sensor. Note that some errors will cause the sensor to stop working. You should call isActive() to determine if the sensor is still running. */ /*! \fn QSensor::availableSensorsChanged() This signal is emitted when the list of available sensors has changed. The sensors available to a program will not generally change over time however some of the available sensors may represent hardware that is not permanently connected. For example, a game controller that is connected via bluetooth would become available when it was on and would become unavailable when it was off. \sa QSensor::sensorTypes(), QSensor::sensorsForType() */ /*! \property QSensor::maxBufferSize The property holds the maximum buffer size. Note that this may be 1, in which case the sensor does not support any form of buffering. In that case, isFeatureSupported(QSensor::Buffering) will also return false. \sa QSensor::bufferSize, QSensor::efficientBufferSize */ int QSensor::maxBufferSize() const { Q_D(const QSensor); return d->maxBufferSize; } /*! \since 5.1 Sets the maximum buffer size to \a maxBufferSize. This is to be called from the backend. */ void QSensor::setMaxBufferSize(int maxBufferSize) { Q_D(QSensor); if (d->maxBufferSize != maxBufferSize) { d->maxBufferSize = maxBufferSize; emit maxBufferSizeChanged(maxBufferSize); } } /*! \property QSensor::efficientBufferSize The property holds the most efficient buffer size. Normally this is 1 (which means no particular size is most efficient). Some sensor drivers have a FIFO buffer which makes it more efficient to deliver the FIFO's size worth of readings at one time. \sa QSensor::bufferSize, QSensor::maxBufferSize */ int QSensor::efficientBufferSize() const { Q_D(const QSensor); return d->efficientBufferSize; } /*! \since 5.1 Sets the efficient buffer size to \a efficientBufferSize. This is to be called from the backend. */ void QSensor::setEfficientBufferSize(int efficientBufferSize) { Q_D(QSensor); if (d->efficientBufferSize != efficientBufferSize) { d->efficientBufferSize = efficientBufferSize; emit efficientBufferSizeChanged(efficientBufferSize); } } /*! \property QSensor::bufferSize This property holds the size of the buffer. By default, the buffer size is 1, which means no buffering. If the maximum buffer size is 1, then buffering is not supported by the sensor. Setting bufferSize greater than maxBufferSize will cause maxBufferSize to be used. Buffering is turned on when bufferSize is greater than 1. The sensor will collect the requested number of samples and deliver them all to the application at one time. They will be delivered to the application as a burst of changed readings so it is particularly important that the application processes each reading immediately or saves the values somewhere else. If stop() is called when buffering is on-going, the partial buffer is not delivered. When the sensor is started with buffering option, values are collected from that moment onwards. There is no pre-existing buffer that can be utilized. Some backends like Blackberry only support enabling or disabling the buffer and do not give control over the size. In this case, the maxBufferSize and efficientBufferSize properties might not be set at all, even though buffering is supported. Setting the bufferSize property to any value greater than 1 will enable buffering. After the sensor has been started, the bufferSize property will be set to the actual value by the backend. On Blackberry, buffering will not wait until the buffer is full to deliver new readings. Instead, the buffer will be used if the backend does not manage to retrieve the readings in time, for example when the event loop is blocked for too long. Without a buffer, these readings would simply be dropped. \sa QSensor::maxBufferSize, QSensor::efficientBufferSize */ int QSensor::bufferSize() const { Q_D(const QSensor); return d->bufferSize; } void QSensor::setBufferSize(int bufferSize) { Q_D(QSensor); if (d->bufferSize != bufferSize) { d->bufferSize = bufferSize; emit bufferSizeChanged(bufferSize); } } // ===================================================================== /*! \class QSensorFilter \ingroup sensors_main \inmodule QtSensors \brief The QSensorFilter class provides an efficient callback facility for asynchronous notifications of sensor changes. Some sensors (eg. the accelerometer) are often accessed very frequently. This may be slowed down by the use of signals and slots. The QSensorFilter interface provides a more efficient way for the sensor to notify your class that the sensor has changed. Additionally, multiple filters can be added to a sensor. They are called in order and each filter has the option to modify the values in the reading or to suppress the reading altogether. Note that the values in the class returned by QSensor::reading() will not be updated until after the filters have been run. \sa filter() */ /*! \internal */ QSensorFilter::QSensorFilter() : m_sensor(0) { } /*! Notifies the attached sensor (if any) that the filter is being destroyed. */ QSensorFilter::~QSensorFilter() { if (m_sensor) m_sensor->removeFilter(this); } /*! \fn QSensorFilter::filter(QSensorReading *reading) This function is called when the sensor \a reading changes. The filter can modify the reading. Returns true to allow the next filter to receive the value. If this is the last filter, returning true causes the signal to be emitted and the value is stored in the sensor. Returns false to drop the reading. */ /*! \internal */ void QSensorFilter::setSensor(QSensor *sensor) { m_sensor = sensor; } // ===================================================================== /*! \class QSensorReading \ingroup sensors_main \inmodule QtSensors \brief 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. */ /*! \internal */ QSensorReading::QSensorReading(QObject *parent, QSensorReadingPrivate *_d) : QObject(parent) , d(_d?_d:new QSensorReadingPrivate) { } /*! \internal */ QSensorReading::~QSensorReading() { } /*! \property QSensorReading::timestamp \brief 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). \b{Note that some platforms do not deliver timestamps correctly}. Applications should be prepared for occasional issues that cause timestamps to jump backwards. */ /*! Returns the timestamp of the reading. */ quint64 QSensorReading::timestamp() const { return d->timestamp; } /*! Sets the \a timestamp of the reading. */ void QSensorReading::setTimestamp(quint64 timestamp) { d->timestamp = timestamp; } /*! 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. */ int QSensorReading::valueCount() const { const QMetaObject *mo = metaObject(); return mo->propertyCount() - mo->propertyOffset(); } /*! Returns the value of the property at \a 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. \code QAccelerometerReading *reading = ...; qreal x = reading->x(); \endcode You can also access a property by name. To do this you must call QObject::property(). \code qreal x = reading->property("x").value(); \endcode Finally, you can access values via numeric index. \code qreal x = reading->value(0).value(); \endcode Note that value() can only access properties declared with Q_PROPERTY() in sub-classes of QSensorReading. \sa valueCount(), QObject::property() */ QVariant QSensorReading::value(int index) const { // get them meta-object const QMetaObject *mo = metaObject(); // determine the index of the property we want index += mo->propertyOffset(); // get the meta-property QMetaProperty property = mo->property(index); // read the property return property.read(this); } /*! \fn QSensorReading::copyValuesFrom(QSensorReading *other) \internal Copy values from other into this reading. Implemented by sub-classes using the DECLARE_READING() and IMPLEMENT_READING() macros. Note that this method should only be called by QSensorBackend. */ void QSensorReading::copyValuesFrom(QSensorReading *other) { QSensorReadingPrivate *my_ptr = d.data(); QSensorReadingPrivate *other_ptr = other->d.data(); /* Do a direct copy of the private class */ *(my_ptr) = *(other_ptr); } /*! \fn QSensorReading::d_ptr() \internal No longer used. Exists to keep the winscw build happy. */ /*! \macro DECLARE_READING(classname) \relates QSensorReading \brief The DECLARE_READING macro adds some required methods to a reading class. This macro should be used for all reading classes. Pass the \a classname of your reading class. \code class MyReading : public QSensorReading { Q_OBJECT Q_PROPERTY(qreal myprop READ myprop) DECLARE_READING(MyReading) public: qreal myprop() const; vod setMyprop(qreal myprop); }; \endcode \sa IMPLEMENT_READING() */ /*! \macro IMPLEMENT_READING(classname) \relates QSensorReading \brief 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 \a classname of your reading class. \code IMPLEMENT_READING(MyReading) \endcode \sa DECLARE_READING() */ #include "moc_qsensor.cpp" QT_END_NAMESPACE