Introduction¶

License¶

PyQt5 is dual licensed on all platforms under the Riverbank Commercial License and the GPL v3. Your PyQt5 license must be compatible with your Qt license. If you use the GPL version then your own code must also use a compatible license.

PyQt5, unlike Qt, is not available under the LGPL.

You can purchase a commercial PyQt5 license here.

PyQt5 Components¶

PyQt5 comprises a number of different components. First of all there are a number of Python extension modules. These are all installed in the PyQt5 Python package.

• QAxContainer contains classes that allow access to ActiveX controls and COM objects. It does not support the ability to write ActiveX servers in Python. It is only available under Windows.

• QtBluetooth contains classes that enables an application to scan for devices and connect and interact with them.

• QtCore contains the core classes, including the event loop and Qt's signal and slot mechanism. It also includes platform independent abstractions for animations, state machines, threads, mapped files, shared memory, regular expressions, and user and application settings.

• QtDBus contains classes that support Inter-Process Communication using the D-Bus protocol. It is not available under Windows.

• QtDesigner contains classes that allow Qt Designer to be extended using PyQt5. See Writing Qt Designer Plugins for a full description of how to do this.

• QtGui contains classes for windowing system integration, event handling, 2D graphics, basic imaging, fonts and text. It also containes a complete set of OpenGL and OpenGL ES bindings (see Support for OpenGL). Application developers would normally use this with higher level APIs such as those contained in the QtWidgets module.

• QtHelp contains classes for creating and viewing searchable documentation.

• QtLocation contains classes for accessing geocoding and navigation information, and also place search. It allows the creation of mapping solutions using data from some of the popular location services.

• QtMacExtras contains additional classes that are specific to OS X and iOS.

• QtMultimedia contains classes to handle multimedia content and APIs to access camera and radio functionality.

• QtMultimediaWidgets contains classes to handle multimedia content in QtWidgets based applications.

• QtNetwork contains classes for writing UDP and TCP clients and servers. It includes classes that implement HTTP clients and support DNS lookups.

• QtNfc contains classes to provide connectivity between NFC enabled devices. The NFC API provides APIs for interacting with NFC Forum Tags and NFC Forum Devices, including target detection and loss, registering NDEF message handlers, reading and writing NDEF messages on NFC Forum Tags and sending tag specific commands.

• QtOpenGL contains classes that allow the use of OpenGL in rendering 3D graphics in QtWidgets based applications.

• QtPositioning contains classes to determine a position by using a variety of possible sources, including satellite, or Wi-Fi, or a text file, and so on. That information can then be used to, for example, determine a position on a map. In addition satellite information can be retrieved and area based monitoring can be performed.

• QtPrintSupport contains classes to allow applications to print to locally attached and remote printers. It also enables the generation of PostScript and PDF files.

• QtQml contains classes to allow applications to integrate support for QML and JavaScript. Python objects can be exported to QML or be created from QML in the same way that Qt allows the same with C++ instances. See Integrating Python and QML for a fuller description of how to do this.

• QtQuick contains classes that provide the basic elements necessary for creating user interfaces with QML.

• QtQuickWidgets contains classes that support the display of a QML scene in a traditional widget.

• QtSensors contains classes that provide access to a system's hardware sensors including accelerometers, altimeters, ambient light and temperature sensors, gyroscopes and magnetometers. Note that sensor gestures are not currently supported.

• QtSerialPort contains classes that provide access to a system's serial ports.

• QtSql contains classes that integrate with SQL databases. It includes editable data models for database tables that can be used with GUI classes. It also includes an implementation of SQLite.

• QtSvg contains classes for displaying the contents of SVG files.

• QtTest contains functions that enable unit testing of PyQt5 applications. (PyQt5 does not implement the complete Qt unit test framework. Instead it assumes that the standard Python unit test framework will be used and implements those functions that simulate a user interacting with a GUI.) In addition the QSignalSpy class provides easy introspection of Qt's signals and slots.

• QtWebChannel contains classes for transparently accessing QObject or QML objects from HTML clients.

• QtWebEngineCore contains core classes used by the QtWebEngineWidgets module.

• QtWebEngineWidgets contains classes for a Chromium based implementation of a web browser. This supercedes the QtWebKit module and provides better and up-to-date support for HTML, CSS and JavaScript features. However it also consumes more resources and doesn't give direct access to the network stack and the HTML document via C++ APIs.

  Note

  QtWebEngineWidgets is not normally available under Windows using versions of Python earlier than v3.5 because of compiler incompatibilities.

• QtWebKit contains classes for a WebKit2 based implementation of a web browser.

• QtWebKitWidgets contains classes for a WebKit1 based implementation of a web browser for use in QtWidgets based applications.

• QtWebSockets contains classes that implement the WebSocket protocol described in RFC 6455.

• QtWidgets contains classes that provide a set of UI elements to create classic desktop-style user interfaces.

• QtWinExtras contains additional classes that are specific to Windows, for example providing access to Jump Lists, a progress indicator on a taskbar button, and a thumbnail toolbar.

• QtX11Extras contains additional classes that are specific to X11.

• QtXml module. This module contains classes that implement SAX and DOM interfaces to Qt's XML parser.

• QtXmlPatterns contains classes that provide support for XPath, XQuery, XSLT and XML Schema validation.

• Enginio implements the client-side library for accessing the Qt Cloud Services Managed Application Runtime.

• Qt consolidates the classes contained in all of the modules described above into a single module. This has the advantage that you don't have to worry about which underlying module contains a particular class. It has the disadvantage that it loads the whole of the Qt framework, thereby increasing the memory footprint of an application. Whether you use this consolidated module, or the individual component modules is down to personal taste.

• uic contains classes for handling the .ui files created by Qt Designer that describe the whole or part of a graphical user interface. It includes classes that load a .ui file and render it directly, and classes that generate Python code from a .ui file for later execution.

PyQt5 contains plugins that enable Qt Designer and qmlscene to be extended using Python code. See Writing Qt Designer Plugins and Integrating Python and QML respectively for the details.

PyQt5 also contains a number of utility programs.

• pyuic5 corresponds to the Qt uic utility. It converts QtWidgets based GUIs created using Qt Designer to Python code.
• pyrcc5 corresponds to the Qt rcc utility. It embeds arbitrary resources (eg. icons, images, translation files) described by a resource collection file in a Python module.
• pylupdate5 corresponds to the Qt lupdate utility. It extracts all of the translatable strings from Python code and creates or updates .ts translation files. These are then used by Qt Linguist to manage the translation of those strings.

The DBus support module is installed as dbus.mainloop.pyqt5. This module provides support for the Qt event loop in the same way that the dbus.mainloop.glib included with the standard dbus-python bindings package provides support for the GLib event loop. The API is described in DBus Support. It is only available if the dbus-python v0.80 (or later) bindings package is installed. The QtDBus module provides a more Qt-like interface to DBus.

When PyQt5 is configured a file called PyQt5.api is generated. This can be used by the QScintilla editor component to enable the use of auto-completion and call tips when editing PyQt5 code. The API file is installed automatically if QScintilla is already installed.

PyQt5 includes a large number of examples. These are ports to Python of many of the C++ examples provided with Qt. They can be found in the examples directory.

Finally, PyQt5 contains the .sip files used by SIP to generate PyQt5 itself. These can be used by developers of bindings of other Qt based class libraries.

An Explanation of Version Numbers¶

Historically the version number of PyQt bears no relation to the version of Qt supported. It's no longer even true that PyQt4 requires Qt v4 as it will also build against Qt v5. People sometimes mistakenly believe that, for example, PyQt4 v4.8 is needed when building against Qt v4.8.

When refering to a version number we assume it consists of three numbers separated by a dot. These are the major number, the minor number and the maintenance number. The major number will always be 5. The maintenance number may be omitted if it is 0.

Starting with PyQt5 the version number of PyQt5 is tied, to a certain extent, to the version of Qt v5. This is based on the following assumptions.

• All parts of the Qt API will be supported throughout the life of Qt v5 even though some may be marked as deprecated or obsolete at some point.
• When new parts of the Qt API are introduced the minor number of the version will be increased and the maintenance number will be reset to 0.

Therefore, for PyQt5 v5.n.* the following are true.

• It will build against any version of Qt v5, but will not support any new features introduced in Qt v5.n+1 or later.
• It will support all the features of supported modules of Qt v5.n or earlier.
• Support for new modules may be added to PyQt5 at any time. This would result in a change of maintenance number only.

The maintenance numbers of PyQt5 and Qt v5 are entirely unrelated to each other.

So, for example, PyQt5 v5.1 will build against Qt v5.2 but will not support any new features introduced in Qt v5.2. PyQt5 v5.1 will support all the features of supported modules of Qt v5.0 and those new features introduced in Qt v5.1.

In summary, just as with PyQt4, you should always try and use the latest version of PyQt5 no matter what version of Qt v5 you are using.