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QValueSpaceSubscriber Class Reference

The QValueSpaceSubscriber class allows applications to read and subscribe to Value Space paths. More...

 #include <QValueSpaceSubscriber>

Inherits: QObject.

This class was introduced in Qt Mobility 1.0.

Properties

  • 1 property inherited from QObject

Public Functions

QValueSpaceSubscriber ( QObject * parent = 0 )
QValueSpaceSubscriber ( const QString & path, QObject * parent = 0 )
QValueSpaceSubscriber ( QValueSpace::LayerOptions filter, const QString & path, QObject * parent = 0 )
QValueSpaceSubscriber ( const QUuid & uuid, const QString & path, QObject * parent = 0 )
virtual ~QValueSpaceSubscriber ()
void cd ( const QString & path )
void cdUp ()
bool isConnected () const
QString path () const
void setPath ( const QString & path )
void setPath ( QValueSpaceSubscriber * subscriber )
QStringList subPaths () const
QVariant value ( const QString & subPath = QString(), const QVariant & def = QVariant() ) const
  • 29 public functions inherited from QObject

Signals

void contentsChanged ()

Additional Inherited Members

  • 1 public slot inherited from QObject
  • 1 public variable inherited from QObject
  • 4 static public members inherited from QObject
  • 7 protected functions inherited from QObject
  • 2 protected variables inherited from QObject

Detailed Description

The QValueSpaceSubscriber class allows applications to read and subscribe to Value Space paths.

By default QValueSpaceSubscriber can read values from and report change notifications for all available Value Space layers. Only data from the layer with the highest order and that contains the specific key is returned by this class.

The layers that QValueSpaceSubscriber accesses can be limited by specifying either a filter or a QUuid at construction time.

Applications subscribe to a particular path in the Value Space. If anything under that path changes the contextChanged() signal is emitted. For example given the schema:

 /Device/Buttons = 3
 /Device/Buttons/1/Name = Menu
 /Device/Buttons/1/Usable = true
 /Device/Buttons/2/Name = Select
 /Device/Buttons/2/Usable = false
 /Device/Buttons/3/Name = Back
 /Device/Buttons/3/Usable = true

The code:

     QValueSpaceSubscriber *buttons = new QValueSpaceSubscriber("/Device/Buttons");
     QObject::connect(buttons, SIGNAL(contentsChanged()), this, SLOT(buttonInfoChanged()));

will invoke the buttonInfoChanged() slot whenever any value under /Device/Buttons changes. This includes the value of /Device/Buttons itself, a change of a subpath such as /Device/Buttons/2/Name or the creation or removal of a subpath.

Property Documentation

path : QString

This property holds the current path that the QValueSpaceSubscriber refers to.

Settings this property causes the QValueSpaceSubscriber to disconnect and reconnect to the Value Space with the new path. As a result all signal/slot connections are disconnected.

This property was introduced in Qt Mobility 1.0.

Access functions:

QString path () const
void setPath ( const QString & path )
void setPath ( QValueSpaceSubscriber * subscriber )

value : const QVariant

This property holds the value of the path that this QValueSpaceSubscriber refers to.

This property was introduced in Qt Mobility 1.0.

Notifier signal:

void contentsChanged ()

Member Function Documentation

QValueSpaceSubscriber::QValueSpaceSubscriber ( QObject * parent = 0 )

Constructs a QValueSpaceSubscriber with the specified parent that refers to the root path.

The constructed Value Space subscriber will access all available layers.

This function was introduced in Qt Mobility 1.0.

QValueSpaceSubscriber::QValueSpaceSubscriber ( const QString & path, QObject * parent = 0 )

Constructs a QValueSpaceSubscriber with the specified parent that refers to path.

The constructed Value Space subscriber will access all available layers.

This function was introduced in Qt Mobility 1.0.

QValueSpaceSubscriber::QValueSpaceSubscriber ( QValueSpace::LayerOptions filter, const QString & path, QObject * parent = 0 )

Constructs a QValueSpaceSubscriber with the specified parent that refers to path. The filter parameter is used to limit which layers this QValueSpaceSubscriber will access.

If a layer matching filter is not found, the constructed QValueSpaceSubscriber will be unconnected.

This function was introduced in Qt Mobility 1.0.

See also isConnected().

QValueSpaceSubscriber::QValueSpaceSubscriber ( const QUuid & uuid, const QString & path, QObject * parent = 0 )

Constructs a QValueSpaceSubscriber with the specified parent that refers to path. This QValueSpaceSubscriber will only use the layer identified by uuid.

Use of this constructor is not platform agnostic. If possible use one of the constructors that take a QValueSpace::LayerOptions parameter instead.

If a layer with a matching uuid is not found, the constructed QValueSpaceSubscriber will be unconnected.

This function was introduced in Qt Mobility 1.0.

See also QValueSpace and isConnected().

QValueSpaceSubscriber::~QValueSpaceSubscriber () [virtual]

Destroys the QValueSpaceSubscriber.

This function was introduced in Qt Mobility 1.0.

void QValueSpaceSubscriber::cd ( const QString & path )

Changes the path to the absolute path if path starts with a '/'; otherwise changes to the sub path of the current path.

This function was introduced in Qt Mobility 1.0.

void QValueSpaceSubscriber::cdUp ()

Sets the path to parent of the current path.

This function was introduced in Qt Mobility 1.0.

void QValueSpaceSubscriber::contentsChanged () [signal]

Emitted whenever any value under the current path changes.

Note: that if a value changes multiple times in quick succession, only the most recent value may be accessible via the value() function.

This function was introduced in Qt Mobility 1.0.

bool QValueSpaceSubscriber::isConnected () const

Returns true if this QValueSpaceSubscriber is connected to at least one available layer; otherwise returns false. An unconnected QValueSpaceSubscriber is constructed if the filtering parameters passed to the constructor eliminate all available layers.

This function was introduced in Qt Mobility 1.0.

QStringList QValueSpaceSubscriber::subPaths () const

Returns a list of sub-paths under the current path. For example, given a Value Space tree containing:

 /Settings/Nokia/Device
 /Settings/Nokia/Other
 /Settings/Qt
 /Device/Buttons

QValueSpaceSubscriber("/Settings").subPaths() will return a list containing { Nokia, Qt } in no particular order.

This function was introduced in Qt Mobility 1.0.

QVariant QValueSpaceSubscriber::value ( const QString & subPath = QString(), const QVariant & def = QVariant() ) const

Returns the value of the subPath under this subscriber path, or the value of this subscriber path if subPath is empty. If the value does not exists def is returned.

The following code shows how the subscriber path and subPath relate.

 QValueSpaceSubscriber base("/Settings");
 QValueSpaceSubscriber equiv("/Settings/Nokia/General/Mappings");

 // Is true
 equiv.value() == base.value("Nokia/General/Mappings");

This function was introduced in Qt Mobility 1.0.

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