Home · All Classes · Annotated · Functions

IValueSpaceLayer Class Reference

The IValueSpaceLayer class provides support for adding new logical data layers to the Qtopia Value Space. More...

#include <IValueSpaceLayer>

Inherits QObject.

• List of all members, including inherited members

Public Types

• typedef HANDLE
• enum Properties { Publish }
• enum Type { Server, Client }

Public Functions

• virtual QSet<QByteArray> children ( HANDLE handle ) = 0
• virtual QUuid id () = 0
• virtual HANDLE item ( HANDLE parent, const QByteArray & subPath ) = 0
• virtual QString name () = 0
• virtual unsigned int order () = 0
• virtual void remHandle ( HANDLE handle ) = 0
• virtual void setProperty ( HANDLE handle, Properties property ) = 0
• virtual void shutdown () = 0
• virtual bool startup ( Type type ) = 0
• virtual bool value ( HANDLE handle, QVariant * data ) = 0
• virtual bool value ( HANDLE handle, const QByteArray & subPath, QVariant * data ) = 0

• 36 public functions inherited from QObject

Signals

• void handleChanged ( unsigned int handle )

• 1 signal inherited from QObject

Additional Inherited Members

• 1 property inherited from QObject
• 1 public slot inherited from QObject
• 4 static public members inherited from QObject
• 8 protected functions inherited from QObject
• 2 protected variables inherited from QObject
• 1 static protected member inherited from QObject

Detailed Description

The IValueSpaceLayer class provides support for adding new logical data layers to the Qtopia Value Space.

Member Type Documentation

typedef IValueSpaceLayer::HANDLE

The HANDLE type is an opaque, pointer sized contextual handle used to represent paths within value space layers. HANDLES are only ever created by IValueSpaceLayer::item() and are always released by calls to IValueSpaceLayer::remHandle(). The special, InvalidHandle is reserved to represent an invalid handle.

enum IValueSpaceLayer::Properties

To allow for efficient layer implementations, expensive handle operations, currently only monitoring for changes, are enabled and disabled as needed on a per-handle basis. The Properties enumeration is a bitmask representing the different properties that can exist on a handle.

enum IValueSpaceLayer::Type

Value Space layers are initialized in either a "Server" or a "Client" context. There is only a single server in the value space architecture, and its layers are always initialized before any clients. This distinction allows layers to implement Client/Server architecture if required. If not, layers are free to treat Server and Client contexts identically.

Member Function Documentation

QSet<QByteArray> IValueSpaceLayer::children ( HANDLE handle )   [pure virtual]

Returns the set of children of handle. For example, in a layer providing the following items:

    /Device/Configuration/Applications/FocusedApplication
    /Device/Configuration/Buttons/PrimaryInput
    /Device/Configuration/Name

a request for children of "/Device/Configuration" will return { "Applications", "Buttons", "Name" }.

void IValueSpaceLayer::handleChanged ( unsigned int handle )   [signal]

Emitted whenever the handle's value, or any sub value, changes.

QUuid IValueSpaceLayer::id ()   [pure virtual]

Return a globally unique id for the layer. This id is used to break ordering ties.

HANDLE IValueSpaceLayer::item ( HANDLE parent, const QByteArray & subPath )   [pure virtual]

Returns a new opaque handle for the requested subPath of parent. If parent is an InvalidHandle, subPath is an absolute path.

QString IValueSpaceLayer::name ()   [pure virtual]

Returns the name of the Value Space layer. This name is only used for diagnostics purposes.

unsigned int IValueSpaceLayer::order ()   [pure virtual]

Return the position in the Value Space layer stack that this layer should reside. Higher numbers mean the layer has a higher precedence and its values will "shadow" those below it. If two layers specify the same ordering, the IValueSpaceLayer::id() value is used to break the tie.

void IValueSpaceLayer::remHandle ( HANDLE handle )   [pure virtual]

Releases a handle previously returned from IValueSpaceLayer::item().

void IValueSpaceLayer::setProperty ( HANDLE handle, Properties property )   [pure virtual]

Apply the specified property mask to handle.

void IValueSpaceLayer::shutdown ()   [pure virtual]

Called by the Value Space system to uninitialize each layer. The shutdown call can be used to release any resources in use by the layer.

bool IValueSpaceLayer::startup ( Type type )   [pure virtual]

Called by the Value Space system to initialize each layer. The type parameter will be set accordingly, and layer implementors can use this to implement a client/server architecture if desired.

bool IValueSpaceLayer::value ( HANDLE handle, QVariant * data )   [pure virtual]

Returns the value for a particular handle. If a value is available, the layer will set data and return true. If no value is available, false is returned.

bool IValueSpaceLayer::value ( HANDLE handle, const QByteArray & subPath, QVariant * data )   [pure virtual]

This is an overloaded member function, provided for convenience.

Returns the value for a particular subPath of handle. If a value is available, the layer will set data and return true. If no value is available, false is returned.