CopperSpice API  1.7.2
QResource Class Reference

The QResource class provides an interface for reading directly from resources. More...

Public Methods

 QResource (const QString &file=QString (), const QLocale &locale=QLocale ())
 
 ~QResource ()
 
QString absoluteFilePath () const
 
const uchardata () const
 
QString fileName () const
 
bool isCompressed () const
 
bool isValid () const
 
QLocale locale () const
 
void setFileName (const QString &file)
 
void setLocale (const QLocale &locale)
 
qint64 size () const
 

Static Public Methods

static void addSearchPath (const QString &path)
 
static bool registerResource (const QString &fileName, const QString &resourceRoot=QString ())
 
static bool registerResource (const uchar *rccData, const QString &resourceRoot=QString ())
 
static QStringList searchPaths ()
 
static bool unregisterResource (const QString &fileName, const QString &resourceRoot=QString ())
 
static bool unregisterResource (const uchar *rccData, const QString &resourceRoot=QString ())
 

Protected Methods

QStringList children () const
 
bool isDir () const
 
bool isFile () const
 

Detailed Description

The QResource class provides an interface for reading directly from resources.

QResource is an object that represents a set of data (and possibly children) relating to a single resource entity. QResource gives direct access to the bytes in their raw format. In this way direct access allows reading data without buffer copying or indirection. Indirection is often useful when interacting with the resource entity as if it is a file, this can be achieved with QFile. The data and children behind a QResource are normally compiled into an application/library, but it is also possible to load a resource at runtime. When loaded at run time the resource file will be loaded as one big set of data and then given out in pieces via references into the resource tree.

A QResource can either be loaded with an absolute path, either treated as a file system rooted with a / character, or in resource notation rooted with a : character. A relative resource can also be opened which will be found in the list of paths returned by QDir::searchPaths().

A QResource that is representing a file will have data backing it, this data can possibly be compressed, in which case qUncompress() must be used to access the real data; this happens implicitly when accessed through a QFile. A QResource that is representing a directory will have only children and no data.

Dynamic Resource Loading

A resource can be left out of an application's binary and loaded when it is needed at run-time by using the registerResource() function. The resource file passed into registerResource() must be a binary resource as created by rcc. Further information about binary resources can be found in the Resource System documentation.

This can often be useful when loading a large set of application icons that may change based on a setting, or that can be edited by a user and later recreated. The resource is immediately loaded into memory, either as a result of a single file read operation, or as a memory mapped file.

This approach can prove to be a significant performance gain as only a single file will be loaded, and pieces of data will be given out via the path requested in setFileName().

The unregisterResource() function removes a reference to a particular file. If there are QResources that currently reference resources related to the unregistered file, they will continue to be valid but the resource file itself will be removed from the resource roots, and thus no further QResource can be created pointing into this resource data. The resource itself will be unmapped from memory when the last QResource that points to it is destroyed.

See also
Resource System, QFile, QDir, QFileInfo

Constructor & Destructor Documentation

QResource::QResource ( const QString file = QString(),
const QLocale locale = QLocale() 
)

Constructs a QResource pointing to file. locale is used to load a specific localization of a resource data.

See also
QFileInfo, QDir::searchPaths(), setFileName(), setLocale()
QResource::~QResource ( )

Releases the resources of the QResource object.

Method Documentation

QString QResource::absoluteFilePath ( ) const

Returns the real path that this QResource represents, if the resource was found via the QDir::searchPaths() it will be indicated in the path.

See also
fileName()
void QResource::addSearchPath ( const QString path)
deprecatedstatic
Deprecated:
Use QDir::addSearchPath() with a prefix instead.

Adds path to the search paths searched in to find resources that are not specified with an absolute path. The path must be an absolute path (start with /).

The default search path is to search only in the root (:/). The last path added will be consulted first upon next QResource creation.

QStringList QResource::children ( ) const
protected

Returns a list of all resources in this directory, if the resource represents a file the list will be empty.

See also
isDir()
const uchar * QResource::data ( ) const

Returns direct access to a read only segment of data that this resource represents. If the resource is compressed the data returns is compressed and qUncompress() must be used to access the data. If the resource is a directory 0 is returned.

See also
size(), isCompressed(), isFile()
QString QResource::fileName ( ) const

Returns the full path to the file that this QResource represents as it was passed.

See also
setFileName(), absoluteFilePath()
bool QResource::isCompressed ( ) const

Returns true if the resource represents a file and the data backing it is in a compressed format, false otherwise.

See also
data(), isFile()
bool QResource::isDir ( ) const
protected

Returns true if the resource represents a directory and thus may have children() in it, false if it represents a file.

See also
isFile()
bool QResource::isFile ( ) const
inlineprotected

Returns true if the resource represents a file and thus has data backing it, false if it represents a directory.

See also
isDir()
bool QResource::isValid ( ) const

Returns true if the resource really exists in the resource hierarchy, false otherwise.

QLocale QResource::locale ( ) const

Returns the locale used to locate the data for the QResource.

See also
setLocale()
bool QResource::registerResource ( const QString fileName,
const QString resourceRoot = QString() 
)
static

Registers the resource with the given fileName at the location in the resource tree specified by resourceRoot, and returns true if the file is successfully opened, otherwise returns false.

See also
unregisterResource()
bool QResource::registerResource ( const uchar rccData,
const QString resourceRoot = QString() 
)
static

Registers the resource with the given rccData at the location in the resource tree specified by resourceRoot, and returns true if the file is successfully opened, otherwise returns false.

Warning
The data must remain valid throughout the life of any QFile that may reference the resource data.
See also
unregisterResource()
QStringList QResource::searchPaths ( )
deprecatedstatic
Deprecated:
Use QDir::searchPaths() instead.

Returns the current search path list. This list is consulted when creating a relative resource.

See also
QDir::addSearchPath(), QDir::setSearchPaths()
void QResource::setFileName ( const QString file)

Sets a QResource to point to file which can be can either be absolute, in which case it is opened directly. If it is relative then the file will be searched in QDir::searchPaths().

See also
fileName(), absoluteFilePath()
void QResource::setLocale ( const QLocale locale)

Sets a QResource to only load the localization of resource to for locale. If a resource for the specific locale is not found then the C locale is used.

See also
locale(), setFileName()
qint64 QResource::size ( ) const

Returns the size of the data backing the resource.

See also
data(), isFile()
bool QResource::unregisterResource ( const QString fileName,
const QString resourceRoot = QString() 
)
static

Unregisters the resource with the given fileName at the location in the resource tree specified by resourceRoot, and returns true if the resource is successfully unloaded and no references exist for the resource, otherwise returns false.

See also
registerResource()
bool QResource::unregisterResource ( const uchar rccData,
const QString resourceRoot = QString() 
)
static

Unregisters the resource with the given rccData at the location in the resource tree specified by resourceRoot, and returns true if the resource is successfully unloaded and no references exist into the resource, otherwise returns false.

See also
registerResource()