內容

公共類型
特性
公共函數
公共槽
信號
靜態公共成員
相關非成員
詳細描述
Orientation

QSensor 類

The QSensor class represents a single hardware sensor. 更多...

頭：	#include <QSensor>
qmake:	QT += sensors
Since:	Qt 5.1
繼承：	QObject
繼承者：	QAccelerometer , QAltimeter , QAmbientLightSensor , QAmbientTemperatureSensor , QCompass , QDistanceSensor , QGyroscope , QHolsterSensor , QHumiditySensor , QIRProximitySensor , QLidSensor , QLightSensor , QMagnetometer , QOrientationSensor , QPressureSensor , QProximitySensor , QRotationSensor , QTapSensor ，和 QTiltSensor

公共類型

enum	AxesOrientationMode { FixedOrientation, AutomaticOrientation, UserOrientation }
enum	Feature { Buffering, AlwaysOn, SkipDuplicates, GeoValues, ..., AxesOrientation }

特性

active : bool
alwaysOn : bool
availableDataRates : const qrangelist
axesOrientationMode : AxesOrientationMode
bufferSize : int
busy : const bool
connectedToBackend : const bool
currentOrientation : const int
dataRate : int
description : const QString

efficientBufferSize : const int
error : const int
標識符 : QByteArray
maxBufferSize : const int
outputRange : int
outputRanges : const qoutputrangelist
reading : QSensorReading* const
skipDuplicates : bool
type : const QByteArray
userOrientation : int

1 特性繼承自 QObject

公共函數

	QSensor (const QByteArray & type , QObject * parent = Q_NULLPTR)
virtual	~QSensor ()
void	addFilter (QSensorFilter * filter )
qrangelist	availableDataRates () const
QSensor::AxesOrientationMode	axesOrientationMode () const
int	bufferSize () const
bool	connectToBackend ()
int	currentOrientation () const
int	dataRate () const
QString	description () const
int	efficientBufferSize () const
int	error () const
QList<QSensorFilter *>	過濾 () const
QByteArray	標識符 () const
bool	isActive () const
bool	isAlwaysOn () const
bool	isBusy () const
bool	isConnectedToBackend () const
bool	isFeatureSupported (QSensor::Feature feature ) const
int	maxBufferSize () const
int	outputRange () const
qoutputrangelist	outputRanges () const
QSensorReading *	reading () const
void	removeFilter (QSensorFilter * filter )
void	setActive (bool active )
void	setAlwaysOn (bool alwaysOn )
void	setAxesOrientationMode (QSensor::AxesOrientationMode axesOrientationMode )
void	setBufferSize (int bufferSize )
void	setCurrentOrientation (int currentOrientation )
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 )
void	setUserOrientation (int userOrientation )
bool	skipDuplicates () const
QByteArray	type () const
int	userOrientation () const

31 公共函數繼承自 QObject

公共槽

bool	start ()
void	stop ()

1 公共槽繼承自 QObject

信號

void	activeChanged ()
void	alwaysOnChanged ()
void	availableSensorsChanged ()
void	axesOrientationModeChanged (QSensor::AxesOrientationMode axesOrientationMode )
void	bufferSizeChanged (int bufferSize )
void	busyChanged ()
void	currentOrientationChanged (int currentOrientation )
void	dataRateChanged ()
void	efficientBufferSizeChanged (int efficientBufferSize )
void	maxBufferSizeChanged (int maxBufferSize )
void	readingChanged ()
void	sensorError (int error )
void	skipDuplicatesChanged (bool skipDuplicates )
void	userOrientationChanged (int userOrientation )

2 信號繼承自 QObject

靜態公共成員

QByteArray	defaultSensorForType (const QByteArray & type )
QList<QByteArray>	sensorTypes ()
QList<QByteArray>	sensorsForType (const QByteArray & type )
const QMetaObject	staticMetaObject

9 靜態公共成員繼承自 QObject

typedef	qoutputrangelist
typedef	qrange
typedef	qrangelist

額外繼承成員

9 保護函數繼承自 QObject

詳細描述

The QSensor class represents a single hardware sensor.

通常，傳感器的生命周期為：

Create a sub-class of QSensor on the stack or heap.
通過應用程序按要求設置。
開始接收值。
通過應用程序使用傳感器數據。
停止接收值。

交付傳感器數據憑藉 QSensorReading 及其子類。

取嚮

Some sensors react to screen orientation changes, such as QAccelerometer , QMagnetometer and QRotationSensor . These are so called 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 () 采用 QSensor::AxesOrientation 標誌。

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.

另請參閱 QSensorReading .

成員類型文檔編製

enum QSensor:: AxesOrientationMode

Describes how reading values are affected by the screen orientation.

常量	值	描述
`QSensor::FixedOrientation`	`0`	No automatic rotation is applied to the reading values.
`QSensor::AutomaticOrientation`	`1`	The reading values are automatically rotated based on the screen orientation.
`QSensor::UserOrientation`	`2`	The reading values are rotated based on the angle of the userOrientation 特性。

該枚舉在 Qt 5.1 引入或被修改。

另請參閱 QSensor::axesOrientationMode .

enum QSensor:: Feature

列齣後端可能支持的可選特徵。

The features common to all sensor types are:

常量	值	描述
`QSensor::Buffering`	`0`	The backend supports buffering of readings, controlled by the QSensor::bufferSize 特性。
`QSensor::AlwaysOn`	`1`	The backend supports changing the policy on whether to suspend when idle, controlled by the QSensor::alwaysOn 特性。
`QSensor::SkipDuplicates`	`5`	The backend supports skipping of same or very similar successive readings. This can be enabled by setting the QSensor::skipDuplicates 特性為 true。

The features of QMagnetometer 是：

常量	值	描述
`QSensor::GeoValues`	`2`	The backend supports returning geo values, which can be controlled with the QMagnetometer::returnGeoValues 特性。

The features of QLightSensor 是：

常量	值	描述
`QSensor::FieldOfView`	`3`	The backend specifies its field of view, which can be read from the QLightSensor::fieldOfView 特性。

The features of QAccelerometer 是：

常量	值	描述
`QSensor::AccelerationMode`	`4`	The backend supports switching the acceleration mode of the acceleromter with the QAccelerometer::accelerationMode 特性。

The features of QPressureSensor 是：

常量	值	描述
`QSensor::PressureSensorTemperature`	`7`	The backend provides the pressure sensor's die temperature

所有可定嚮傳感器特徵：

常量	值	描述
`QSensor::AxesOrientation`	`6`	The backend supports changing the axes orientation from the default of QSensor::FixedOrientation to something else.

該枚舉在 Qt 5.0 引入或被修改。

另請參閱 QSensor::isFeatureSupported ().

特性文檔編製

active : bool

This property holds 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.

訪問函數：

bool	isActive () const
void	setActive (bool active )

通知程序信號：

void	activeChanged ()

alwaysOn : bool

This property holds 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.

訪問函數：

bool	isAlwaysOn () const
void	setAlwaysOn (bool alwaysOn )

通知程序信號：

void	alwaysOnChanged ()

availableDataRates : const qrangelist

This property holds 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.

見 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.

訪問函數：

qrangelist

availableDataRates () const

另請參閱 QSensor::dataRate and qrangelist .

axesOrientationMode : AxesOrientationMode

This property holds the mode that affects how the screen orientation changes reading values.

當設為 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 特徵。

當設為 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.

此特性僅用於可定嚮傳感器。

該特性在 Qt 5.1 引入。

訪問函數：

QSensor::AxesOrientationMode	axesOrientationMode () const
void	setAxesOrientationMode (QSensor::AxesOrientationMode axesOrientationMode )

通知程序信號：

void	axesOrientationModeChanged (QSensor::AxesOrientationMode axesOrientationMode )

bufferSize : 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.

若 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 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.

訪問函數：

int	bufferSize () const
void	setBufferSize (int bufferSize )

通知程序信號：

void	bufferSizeChanged (int bufferSize )

另請參閱 QSensor::maxBufferSize and QSensor::efficientBufferSize .

busy : const bool

This property holds 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.

訪問函數：

bool	isBusy () const

另請參閱 busyChanged ().

connectedToBackend : const bool

This property holds 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.

調用 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).

訪問函數：

bool	isConnectedToBackend () const

currentOrientation : const int

This property holds 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.

在 UserOrientation mode, the readings are rotated based on the userOrientation property, and therefore this property is equal to the userOrientation 特性。

在 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.

該特性在 Qt 5.1 引入。

訪問函數：

int	currentOrientation () const

通知程序信號：

void	currentOrientationChanged (int currentOrientation )

dataRate : int

This property holds the data rate that the sensor should be run at.

以赫茲為單位度量。

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.

訪問函數：

int	dataRate () const
void	setDataRate (int rate )

通知程序信號：

void	dataRateChanged ()

另請參閱 QSensor::availableDataRates .

description : const QString

此特性保持用於傳感器的描述性字符串。

訪問函數：

QString

描述 () const

efficientBufferSize : const 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.

訪問函數：

int	efficientBufferSize () const

通知程序信號：

void	efficientBufferSizeChanged (int efficientBufferSize )

另請參閱 QSensor::bufferSize and QSensor::maxBufferSize .

error : const int

此特性保持傳感器設置的最後錯誤代碼。

注意：錯誤代碼特定於傳感器。

訪問函數：

int	error () const

通知程序信號：

void	sensorError (int error )

標識符 : QByteArray

This property holds 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 ().

訪問函數：

QByteArray	標識符 () const
void	setIdentifier (const QByteArray & identifier )

maxBufferSize : const 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. In that case, isFeatureSupported ( QSensor::Buffering ) will also return false.

訪問函數：

int	maxBufferSize () const

通知程序信號：

void	maxBufferSizeChanged (int maxBufferSize )

另請參閱 QSensor::bufferSize and QSensor::efficientBufferSize .

outputRange : int

This property holds the output range in use by the sensor.

This value represents the index in the QSensor::outputRanges list to use.

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.

訪問函數：

int	outputRange () const
void	setOutputRange (int index )

另請參閱 QSensor::outputRanges .

outputRanges : const qoutputrangelist

This property holds 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).

訪問函數：

qoutputrangelist

outputRanges () const

另請參閱 QSensor::outputRange and qoutputrangelist .

reading : QSensorReading * const

This property holds 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 () 信號發射。

訪問函數：

QSensorReading *

reading () const

通知程序信號：

void	readingChanged ()

另請參閱 isConnectedToBackend () 和 start ().

skipDuplicates : 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. 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.

該特性在 Qt 5.1 引入。

訪問函數：

bool	skipDuplicates () const
void	setSkipDuplicates (bool skipDuplicates )

通知程序信號：

void	skipDuplicatesChanged (bool skipDuplicates )

type : const QByteArray

此特性保持傳感器的類型。

訪問函數：

QByteArray

type () const

userOrientation : int

This property holds the angle used for rotating the reading values in the UserOrientation 模式。

當 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.

該特性在 Qt 5.1 引入。

訪問函數：

int	userOrientation () const
void	setUserOrientation (int userOrientation )

通知程序信號：

void	userOrientationChanged (int userOrientation )

成員函數文檔編製

QSensor:: QSensor (const QByteArray & type , QObject * parent = Q_NULLPTR)

Construct the type sensor as a child of 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:


 QSensor *magnetometer = new QSensor(QMagnetometer::type, this);

The right way is to create an instance of the derived class:


 QMagnetometer *magnetometer = new QMagnetometer(this);

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 子類。

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 Grue sensor example .

`[虛擬]` QSensor:: ~QSensor ()

銷毀傳感器。停止傳感器若尚未停止。

`[signal]` void QSensor:: activeChanged ()

此信號發射，當 QSensor::active property has changed.

注意： 通知程序信號對於特性 active .

另請參閱 QSensor::active .

void QSensor:: addFilter ( QSensorFilter * filter )

添加 filter to the sensor.

The sensor does not take ownership of the filter. QSensorFilter will inform the sensor if it is destroyed.

另請參閱 QSensorFilter .

`[signal]` void QSensor:: alwaysOnChanged ()

此信號發射，當 alwaysOn 特性改變。

注意： 通知程序信號對於特性 alwaysOn .

`[signal]` void 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.

另請參閱 QSensor::sensorTypes () 和 QSensor::sensorsForType ().

`[signal]` void 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.


 sensor.start();
 if (sensor.isBusy()) {
     // need to wait for busyChanged signal and try again
 }

bool QSensor:: connectToBackend ()

試著連接到傳感器後端。

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 直接。

注意： 此函數可以被援引，通過元對象係統和從 QML。見 Q_INVOKABLE .

另請參閱 isConnectedToBackend ().

`[static]` QByteArray QSensor:: defaultSensorForType (const QByteArray & type )

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 .

另請參閱 Determining the default sensor for a type .

QList < QSensorFilter *> QSensor:: 過濾 () const

Returns the filters currently attached to the sensor.

另請參閱 QSensorFilter .

bool QSensor:: isFeatureSupported ( QSensor::Feature feature ) const

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 feature , call this function.

The backend needs to be connected, otherwise false will be returned. Calling connectToBackend () 或 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.

該函數在 Qt 5.0 引入。

注意： 此函數可以被援引，通過元對象係統和從 QML。見 Q_INVOKABLE .

`[signal]` void 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.

注意： 通知程序信號對於特性 reading .

另請參閱 start ().

void QSensor:: removeFilter ( QSensorFilter * filter )

移除 filter from the sensor.

另請參閱 QSensorFilter .

`[signal]` void QSensor:: sensorError ( int error )

此信號發射，當 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.

注意： 通知程序信號對於特性 error .

`[static]` QList < QByteArray > QSensor:: sensorTypes ()

Returns a list of all sensor types.

`[static]` QList < QByteArray > QSensor:: sensorsForType (const QByteArray & type )

Returns a list of ids for each of the sensors for type . If there are no sensors of that type available the list will be empty.

void QSensor:: setCurrentOrientation ( int currentOrientation )

Sets the current screen orientation to currentOrientation . This is to be called from the backend whenever the screen orientation or the userOrientation 特性改變。

該函數在 Qt 5.1 引入。

另請參閱 currentOrientation ().

void QSensor:: setEfficientBufferSize ( int efficientBufferSize )

Sets the efficient buffer size to efficientBufferSize . This is to be called from the backend.

該函數在 Qt 5.1 引入。

另請參閱 efficientBufferSize ().

void QSensor:: setMaxBufferSize ( int maxBufferSize )

Sets the maximum buffer size to maxBufferSize . This is to be called from the backend.

該函數在 Qt 5.1 引入。

另請參閱 maxBufferSize ().

void QSensor:: setSkipDuplicates ( bool skipDuplicates )

Sets the duplicate skipping to skipDuplicates .

該函數在 Qt 5.1 引入。

注意： setter 函數對於特性 skipDuplicates .

另請參閱 skipDuplicates ().

`[signal]` void QSensor:: skipDuplicatesChanged ( bool skipDuplicates )

此信號發射，當 skipDuplicates 特性改變。

該函數在 Qt 5.1 引入。

注意： 通知程序信號對於特性 skipDuplicates .

`[slot]` bool QSensor:: start ()

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 () 信號已發射。


     connect(sensor, SIGNAL(readingChanged()), this, SLOT(checkReading()));
     sensor->start();
 }
 void MyClass::checkReading() {
     sensor->reading()->x();

另請參閱 QSensor::busy .

`[slot]` void QSensor:: stop ()

Stop retrieving values from the sensor.

This releases the sensor so that other processes can use it.

另請參閱 QSensor::busy .

內容

QSensor 類

公共類型

特性

公共函數

公共槽

信號

靜態公共成員

相關非成員

額外繼承成員

詳細描述

取嚮

成員類型文檔編製

enum QSensor:: AxesOrientationMode

enum QSensor:: Feature

特性文檔編製

active : bool

alwaysOn : bool

availableDataRates : const qrangelist

axesOrientationMode : AxesOrientationMode

bufferSize : int

busy : const bool

connectedToBackend : const bool

currentOrientation : const int

dataRate : int

description : const QString

efficientBufferSize : const int

error : const int

標識符 : QByteArray

maxBufferSize : const int

outputRange : int

outputRanges : const qoutputrangelist

reading : QSensorReading * const

skipDuplicates : bool

type : const QByteArray

userOrientation : int

成員函數文檔編製

QSensor:: QSensor (const QByteArray & type , QObject * parent = Q_NULLPTR)

[虛擬] QSensor:: ~QSensor ()

[signal] void QSensor:: activeChanged ()

void QSensor:: addFilter ( QSensorFilter * filter )

[signal] void QSensor:: alwaysOnChanged ()

[signal] void QSensor:: availableSensorsChanged ()

[signal] void QSensor:: busyChanged ()

bool QSensor:: connectToBackend ()

[static] QByteArray QSensor:: defaultSensorForType (const QByteArray & type )

QList < QSensorFilter *> QSensor:: 過濾 () const

bool QSensor:: isFeatureSupported ( QSensor::Feature feature ) const

[signal] void QSensor:: readingChanged ()

void QSensor:: removeFilter ( QSensorFilter * filter )

[signal] void QSensor:: sensorError ( int error )

[static] QList < QByteArray > QSensor:: sensorTypes ()

[static] QList < QByteArray > QSensor:: sensorsForType (const QByteArray & type )

void QSensor:: setCurrentOrientation ( int currentOrientation )

void QSensor:: setEfficientBufferSize ( int efficientBufferSize )

void QSensor:: setMaxBufferSize ( int maxBufferSize )

void QSensor:: setSkipDuplicates ( bool skipDuplicates )

[signal] void QSensor:: skipDuplicatesChanged ( bool skipDuplicates )

[slot] bool QSensor:: start ()

[slot] void QSensor:: stop ()

相關非成員

typedef qoutputrangelist

typedef qrange

typedef qrangelist

`[虛擬]` QSensor:: ~QSensor ()

`[signal]` void QSensor:: activeChanged ()

`[signal]` void QSensor:: alwaysOnChanged ()

`[signal]` void QSensor:: availableSensorsChanged ()

`[signal]` void QSensor:: busyChanged ()

`[static]` QByteArray QSensor:: defaultSensorForType (const QByteArray & type )

`[signal]` void QSensor:: readingChanged ()

`[signal]` void QSensor:: sensorError ( int error )

`[static]` QList < QByteArray > QSensor:: sensorTypes ()

`[static]` QList < QByteArray > QSensor:: sensorsForType (const QByteArray & type )

`[signal]` void QSensor:: skipDuplicatesChanged ( bool skipDuplicates )

`[slot]` bool QSensor:: start ()

`[slot]` void QSensor:: stop ()