QGyroscope
Since: 1.2
#include <QtSensors/QGyroscope>
More information will be added here shortly. For now, you'll find more extensive information about this class in the Qt reference for QGyroscope
QtSensors
The QGyroscope class is a convenience wrapper around QSensor.
The only behavioural difference is that this class sets the type properly.
This class also features a reading() function that returns a QGyroscopeReading instead of a QSensorReading.
For details about how the sensor works, see QGyroscopeReading.
Overview
Inheritance
QSensor | ||
QGyroscope |
Properties Index
Only has inherited properties
bool | active![]() |
bool | alwaysOn![]() |
QtMobility::qrangelist | availableDataRates [read-only]![]() |
int | bufferSize![]() |
bool | busy [read-only]![]() |
bool | connectedToBackend [read-only]![]() |
int | dataRate![]() |
QString | description [read-only]![]() |
int | efficientBufferSize [read-only]![]() |
int | error [read-only]![]() |
int | maxBufferSize [read-only]![]() |
int | outputRange![]() |
QtMobility::qoutputrangelist | outputRanges [read-only]![]() |
QSensorReading | reading [read-only]![]() |
QByteArray | sensorid![]() |
bool | skipDuplicates![]() |
Public Static Attributes Index
char const *const | type |
Public Functions Index
QGyroscope (QObject *parent=0) | |
virtual | ~QGyroscope () |
QGyroscopeReading * | reading () const |
void | addFilter (QSensorFilter *filter)![]() |
qrangelist | availableDataRates () const ![]() |
int | bufferSize () const ![]() |
Q_INVOKABLE bool | connectToBackend ()![]() |
int | dataRate () const ![]() |
QString | description () const ![]() |
int | efficientBufferSize () const ![]() |
int | error () const ![]() |
QList< QSensorFilter * > | filters () const ![]() |
QByteArray | identifier () const ![]() |
bool | isActive () const ![]() |
bool | isAlwaysOn () const ![]() |
bool | isBusy () const ![]() |
bool | isConnectedToBackend () const ![]() |
int | maxBufferSize () const ![]() |
int | outputRange () const ![]() |
qoutputrangelist | outputRanges () const ![]() |
QSensor (const QByteArray &type, QObject *parent=0)![]() | |
void | removeFilter (QSensorFilter *filter)![]() |
void | setActive (bool active)![]() |
void | setAlwaysOn (bool alwaysOn)![]() |
void | setBufferSize (int bufferSize)![]() |
void | setDataRate (int rate)![]() |
void | setEfficientBufferSize (int efficientBufferSize)![]() |
void | setIdentifier (const QByteArray &identifier)![]() |
void | setMaxBufferSize (int maxBufferSize)![]() |
void | setOutputRange (int index)![]() |
void | setSkipDuplicates (bool skipDuplicates)![]() |
bool | skipDuplicates () const ![]() |
QByteArray | type () const ![]() |
Static Public Functions Index
Only has inherited static public functions
QByteArray | defaultSensorForType (const QByteArray &type)![]() |
QList< QByteArray > | sensorsForType (const QByteArray &type)![]() |
QList< QByteArray > | sensorTypes ()![]() |
Protected Functions Index
Signals Index
Only has inherited signals
void | activeChanged ()![]() |
void | alwaysOnChanged ()![]() |
void | availableSensorsChanged ()![]() |
void | bufferSizeChanged (int bufferSize)![]() |
void | busyChanged ()![]() |
void | dataRateChanged ()![]() |
void | efficientBufferSizeChanged (int efficientBufferSize)![]() |
void | maxBufferSizeChanged (int maxBufferSize)![]() |
void | readingChanged ()![]() |
void | sensorError (int error)![]() |
void | skipDuplicatesChanged (bool skipDuplicates)![]() |
Properties
(Only has inherited properties)
bool
a value to indicate if the sensor is active.
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.
1.1
bool
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.
QtMobility::qrangelist
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.
1.0
int
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.
bool
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.
1.0
bool
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.
1.0
int
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.
1.0
int
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.
int
the last error code set on the sensor.
1.0
int
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.
int
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.
1.0
QtMobility::qoutputrangelist
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).
1.0
QSensorReading
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.
isConnectedToBackend(), start()
1.0
QByteArray
the backend identifier for the sensor.
1.0
bool
Indicates whether duplicate reading values should be omitted.
When duplicate skipping is enabled, successive readings with the same or very similar values are omitted and skipped. 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. It is disabled by default.
Duplicate skipping can only be changed while the sensor is not active.
Public Static Attributes
char const *const
the type of the sensor.
1.0
Public Functions
Construct the sensor as a child of parent.
1.2
virtual
Destructor.
1.2
void 
Add a filter to the sensor.
The sensor does not take ownership of the filter. QSensorFilter will inform the sensor if it is destroyed.
1.0
int 
Q_INVOKABLE bool 
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.
isConnectedToBackend()
1.0
int 
int 
int 
bool 
bool 
bool 
bool 
int 
int 
Construct the type sensor as a child of parent.
1.0
void 
void 
void 
void 
void 
Sets the efficient buffer size to efficientBufferSize.
This is to be called from the backend.
void 
void 
Sets the maximum buffer size to maxBufferSize.
This is to be called from the backend.
void 
void 
Sets the duplicate skipping to skipDuplicates.
bool 
Static Public Functions
(Only has inherited static public functions)
QByteArray 
Returns the default sensor identifier for type.
This is set in a config file and can be overridden if required. If no default is available the system will return the first registered sensor for type.
Note that there is special case logic to prevent the generic plugin's backends from becoming the default when another backend is registered for the same type. This logic means that a backend identifier starting with {generic.} will only be the default if no other backends have been registered for that type or if it is specified in {Sensors.conf}.
{Determining the default sensor for a type}
1.0
QList< QByteArray > 
Returns a list of ids for each of the sensors for type.
1.0
Protected Functions
(Only has inherited protected functions)
QSensorPrivate * 
Public Slots
(Only has inherited public slots)
bool 
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.
sensor->start(); sensor->reading()->x(); // no data available
To work correctly, the code that accesses the reading should ensure the readingChanged() signal has been emitted.
connect(sensor, SIGNAL(readingChanged()), this, SLOT(checkReading())); sensor->start(); } void MyClass::checkReading() { sensor->reading()->x();
1.0
void 
Stop retrieving values from the sensor.
This releases the sensor so that other processes can use it.
1.0
Signals
(Only has inherited signals)
void 
This signal is emitted when the alwaysOn property changes.
void 
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 avilable 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.
1.2
void 
void 
This signal is emitted when the sensor is no longer busy.
This can be used to grab a sensor when it becomes available.
sensor.start(); if (sensor.isBusy()) { // need to wait for busyChanged signal and try again }
1.0
void 
void 
void 
void 
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.
1.0
void 
This signal is emitted when an error code is set on the sensor.
1.0
void 
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