Qt for Python/GettingStarted

From Qt Wiki
< Qt for Python
Revision as of 08:55, 23 April 2018 by Croitor Alexandru (talk | contribs) (setup.py build script)

Jump to: navigation, search

Getting Started

You can install PySide2 by building the source package yourself.

After cloning the official repository you must follow the instructions for your specific system.

Platform Requirements

  • Python:
    • Python 3 (version >= 3.5 recommended) and Python 2 (version >= 2.7 recommended).
  • Qt:
    • 5.6 onward are supported, but 5.9 (recommended).
  • libclang:
    • The libclang library (C-bindings), version 3.9 or higher is required for building using the PySide 5.9 branch.
    • Prebuilt versions of it can be downloaded from download.qt.io.
  • CMake (version >= 3.1 required) :
    • The build system required by for building PySide2.


Pre-release wheels are available in http://download.qt.io/snapshots/ci/pyside/ You can install Qt for Python via pip, for example to install the latest 5.9:

pip install --index-url=http://download.qt.io/snapshots/ci/pyside/5.9/latest/ pyside2 --trusted-host download.qt.io

Building PySide2

The building processes are covered in the platform pages.

setup.py build script

The script setup.py in the top level repository is used to build and install the PySide2 package. It takes a mode argument (build or install) and several options (more options are documented in setup.py itself).· The main options are:

  • --qmake=/path/to/qmake: Path to qmake of the Qt library to be used
  • --cmake=/path/to/cmake: Path to cmake binary
  • --build-tests: Builds tests along with some helper packages
  • --ignore-git: Prevents setup.py from cloning and checking out the git submodules.
  • --debug: Build in Debug mode (some restrictions apply to Windows, see Build considerations)
  • --reuse-build: Rebuilds only modified files
  • --openssl=C:\Dev\qtdev\OpenSSL-Win64\bin: Path to OpenSSL's bindir which contains dlls (Only required for Windows PySide2 packages)
  • --jobs=#: Number of # processes to use when building
  • --standalone: Copies over the Qt libraries (and other library dependencies) into the PySide2 package to make it work on other machines (on Windows all builds are standalone, even without specifying the command line argument).
  • "--verbose": Prints all compiler invocations when building the package.

A typical invocation looks like:

python setup.py install --build-tests --jobs=4                                                                                                                       

A successful build can be tested by running an example:

 python sources/examples/widgets/widgets/tetrix.py                                                                                                  

You can search for working examples by typing

 cd sources/examples                                                        
 git grep "PySide2 port"

Running Tests

To perform all the available tests, just execute:

python testrunner.py test  > testlog.txt

Note that to successfully run the tests on Windows you need to point the PATH environment variable to the Qt libdir:

set PATH=E:\Qt\5.9\msvc2015_64\bin;%PATH%

Run only one test(qpainter_test):

ctest -R qpainter_test --verbose

Building the Documentation

This is currently unexplored terrain PYSIDE-363, and works at least somewhat only on Linux.

  • The sources are in pyside2/doc
  • libXML2 and libXSLT should be present when building PySide2 (Ubuntu: apt-get install libxml2-dev libxslt1-dev)
  • graphviz + dot should be installed
  • QT_SRC_DIR needs to be set
  • sphinx should be installed (pip install sphinx)
  • qdoc3 is used to generate it

Using Qt Creator as a project explorer

Qt Creator 4.0+ can be used to open the PySide and Shiboken CMakeLists.txt files as projects, and thus provide usual IDE features for developing PySide - project file navigation, code completion (C++ only), following symbols under cursor (C++ only), syntax highlighting, locator usage, debugging, etc.

Currently there is a limitation that Shiboken has to be built first using the terminal, because the installed shiboken CMake packages will have to be specified for the PySide project in Qt Creator.

The steps for opening the projects in Qt Creator are:

  1. Open pyside-setup/sources/shiboken2/CMakeLists.txt, and specify a 5.6 Qt Kit to be used
  2. Build the project as usual (by pressing the build icon for instance)
  3. Open pyside-setup/sources/pyside2/CMakeLists.txt, and specify the same 5.6 Qt Kit
  4. Go to projects tab, and under the Build / CMake section find the Shiboken2_DIR setting. You have to specify the path to the folder where the Shiboken CMake package was installed when you compiled Shiboken from the terminal·
  5. An example path under MacOS is /Users/user/Dev/pyside2-setup/pyside_install/py2.7-qt5.6.1-64bit-debug/lib/cmake/Shiboken2-2.0.0. The path has to be adjusted depending on the user folder name, the version of python and qt, etc
  6. (Optional) On MacOS you also have to set the ALTERNATIVE_QT_INCLUDE_DIR setting to the Qt kit include path (e.g. /Users/user/Dev/qt56_source/include)
  7. Apply the CMake configuration changes (by pressing the button), and you should be able to build PySide

Now you can use the project explorer to look through the source cpp files, python files, use the locator feature to open files and file classes / methods, and other features that Qt Creator provides.

Troubleshooting / Known Issues

  • Qt 5.9 does not work with OpenSSL 1.1
    • When doing a custom Qt build (some unspecified versions for now), It is necessary to have an OpenSSL version of 1.0.x, since there are compatibility issues with newer versions of OpenSSL (see details)
  • PySide2 looks at the system installation if the local Qt version does not have a required module
    • The only workaround is to uninstall any module from the system, then PySide2 can look at only the Qt path currently being use.
  • Qt packages that directly link to OpenSSL (as opposed to runtime discovery) are not currently supported.
  • Make sure that the Python environment location where the PySide2 package will be installed is writable (otherwise you might get various permission denied errors). The install location can be found with 99% probability by running:
python -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())"