QResource

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

Inheritance diagram of PySide2.QtCore.QResource

Synopsis

Functions

Static functions

Detailed Description

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 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 Qt 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 QResource objects 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.

class QResource([file=""[, locale=QLocale()]])
param locale

QLocale

param file

unicode

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

PySide2.QtCore.QResource.Compression

This enum is used by compressionAlgorithm() to indicate which algorithm the RCC tool used to compress the payload.

Constant

Description

QResource.NoCompression

Contents are not compressed ( isCompressed() is false).

QResource.ZlibCompression

Contents are compressed using https://zlib.net and can be decompressed using the qUncompress() function.

QResource.ZstdCompression

Contents are compressed using https://zstd.net. To decompress, use the ZSTD_decompress function from the zstd library.

New in version 5.13.

PySide2.QtCore.QResource.absoluteFilePath()
Return type

unicode

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

See also

fileName()

static PySide2.QtCore.QResource.addSearchPath(path)
Parameters

path – unicode

Note

This function is deprecated.

Use 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.

PySide2.QtCore.QResource.children()
Return type

list of strings

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

See also

isDir()

PySide2.QtCore.QResource.compressionAlgorithm()
Return type

Compression

Returns the compression type that this resource is compressed with, if any. If it is not compressed, this function returns NoCompression .

If this function returns ZlibCompression , you may decompress the data using the qUncompress() function. Up until Qt 5.13, this was the only possible compression algorithm.

If this function returns ZstdCompression , you need to use the Zstandard library functios (<zstd.h> header). Qt does not provide a wrapper. See \l{http://facebook.github.io/zstd/zstd_manual.html}{Zstandard manual}. \sa isCompressed(), data(), isFile()

PySide2.QtCore.QResource.data()
Return type

PyObject

Returns a read only buffer object pointing to the 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 None is returned.

PySide2.QtCore.QResource.fileName()
Return type

unicode

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

PySide2.QtCore.QResource.isCompressed()
Return type

bool

Returns true if the resource represents a file and the data backing it is in a compressed format, false otherwise. If the data is compressed, check compressionAlgorithm() to verify what algorithm to use to decompress the data.

PySide2.QtCore.QResource.isDir()
Return type

bool

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

See also

isFile()

PySide2.QtCore.QResource.isFile()
Return type

bool

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

See also

isDir()

PySide2.QtCore.QResource.isValid()
Return type

bool

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

PySide2.QtCore.QResource.lastModified()
Return type

QDateTime

Returns the date and time when the file was last modified before packaging into a resource.

PySide2.QtCore.QResource.locale()
Return type

QLocale

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

See also

setLocale()

static PySide2.QtCore.QResource.registerResource(rccFilename[, resourceRoot=""])
Parameters
  • rccFilename – unicode

  • resourceRoot – unicode

Return type

bool

static PySide2.QtCore.QResource.registerResourceData(rccData[, resourceRoot=""])
Parameters
  • rccDatauchar

  • resourceRoot – unicode

Return type

bool

static PySide2.QtCore.QResource.searchPaths()
Return type

list of strings

Note

This function is deprecated.

Use searchPaths() instead.

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

PySide2.QtCore.QResource.setFileName(file)
Parameters

file – unicode

Sets a QResource to point to file . file can either be absolute, in which case it is opened directly, if relative then the file will be tried to be found in searchPaths() .

PySide2.QtCore.QResource.setLocale(locale)
Parameters

localeQLocale

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.

PySide2.QtCore.QResource.size()
Return type

qint64

Returns the size of the data backing the resource.

See also

data() isFile()

static PySide2.QtCore.QResource.unregisterResource(rccFilename[, resourceRoot=""])
Parameters
  • rccFilename – unicode

  • resourceRoot – unicode

Return type

bool

static PySide2.QtCore.QResource.unregisterResourceData(rccData[, resourceRoot=""])
Parameters
  • rccDatauchar

  • resourceRoot – unicode

Return type

bool