PySide: Difference between revisions

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(This means that in most cases the same code can be used with both Qt4 and Qt5, as long as it imports the single PySide module.)
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[[PySide|PySide]] is a library that allows you to use the cross-platform graphical user interface (GUI) toolkit Qt with [[Python|Python]]. Qt is a C++ collection of libraries, so its components are normally available from C++, but with the help of PySide, we can use the same components from Python. This means that every complex graphical interface that we can image that can be created in C++, can also be created and modified in Python. A big advantage of using Python is that Qt interfaces can be developed and tested live, as we don't need to compile the source files.
[[PySide|PySide]] is a library that allows you to use the cross-platform graphical user interface (GUI) toolkit Qt with [[Python|Python]]. Qt is a C++ collection of libraries, so its components are normally available from C++, but with the help of PySide, we can use the same components from Python. This means that every complex graphical interface that we can image that can be created in C++, can also be created and modified in Python. An advantage of using Python is that Qt interfaces can be developed and tested live, as we don't need to compile the source files.


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When you [[Installing|install]] FreeCAD, you should get both Qt and PySide as part of the package. If you are [[Compiling|compiling]] yourself, then you must verify that these two libraries are installed, in order for FreeCAD to run correctly. Of course, PySide will only work if Qt is present.

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In the past, FreeCAD used PyQt, another Qt binding for Python, but in 2013 ([https://github.com/FreeCAD/FreeCAD/commit/1dc122dc9a 1dc122dc9a]) the project migrated to PySide because it has a more permissible [[licence|license]].
In the past, FreeCAD used PyQt, another Qt binding for Python, but in 2013 ([https://github.com/FreeCAD/FreeCAD/commit/1dc122dc9a 1dc122dc9a]) the project migrated to PySide because it has a more permissible [[licence|license]].


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For more information see:
For more information see:
* [http://en.wikipedia.org/wiki/PySide Wikipedia:PySide]
* [http://en.wikipedia.org/wiki/PySide Wikipedia:PySide]
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[[File:PySideScreenSnapshot1.jpg]] [[File:PySideScreenSnapshot2.jpg]]
[[File:PySideScreenSnapshot1.jpg]] [[File:PySideScreenSnapshot2.jpg]]
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{{Caption|Examples created with PySide. Left: a simple dialog. Right: a more complex dialog with graphs.}}
{{Caption|Examples created with PySide. Left: a simple dialog. Right: a more complex dialog with graphs.}}


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== Real examples of PySide use ==
== Real examples of PySide use == <!--T:58-->


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It is expected that these examples are useful to get started, and afterwards the user can consult other resources online, or the official documentation.
It is expected that these examples are useful to get started, and afterwards the user can consult other resources online, or the official documentation.


== Documentation ==
== Documentation == <!--T:59-->


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There are some differences in handling of widgets in Qt4 (PySide) and Qt5 (PySide2). The programmer should be aware of these incompatibilities, and should consult the official documentation if something doesn't seem to work as expected in a given platform. Nevertheless, Qt4 is considered obsolete, so most development should target Qt5 and Python 3.
There are some differences in handling of widgets in Qt4 (PySide) and Qt5 (PySide2). The programmer should be aware of these incompatibilities, and should consult the official documentation if something doesn't seem to work as expected in a given platform. Nevertheless, Qt4 is considered obsolete, so most development should target Qt5 and Python 3.


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The PySide documentation refers to the Python-style classes; however, since Qt is originally a C++ library, the same information should be available in the corresponding C++ reference.
The PySide documentation refers to the Python-style classes; however, since Qt is originally a C++ library, the same information should be available in the corresponding C++ reference.
* [https://doc.qt.io/qtforpython/modules.html Qt Modules] available from PySide2 (Qt5).
* [https://doc.qt.io/qtforpython/modules.html Qt Modules] available from PySide2 (Qt5).

Revision as of 20:17, 15 May 2020

Introduction

PySide is a library that allows you to use the cross-platform graphical user interface (GUI) toolkit Qt with Python. Qt is a C++ collection of libraries, so its components are normally available from C++, but with the help of PySide, we can use the same components from Python. This means that every complex graphical interface that we can image that can be created in C++, can also be created and modified in Python. An advantage of using Python is that Qt interfaces can be developed and tested live, as we don't need to compile the source files.

When you install FreeCAD, you should get both Qt and PySide as part of the package. If you are compiling yourself, then you must verify that these two libraries are installed, in order for FreeCAD to run correctly. Of course, PySide will only work if Qt is present.

In the past, FreeCAD used PyQt, another Qt binding for Python, but in 2013 (1dc122dc9a) the project migrated to PySide because it has a more permissible license.

For more information see:

Examples created with PySide. Left: a simple dialog. Right: a more complex dialog with graphs.

PySide in FreeCAD with Qt5

FreeCAD was developed to be used with Python 2 and Qt4. As these two libraries became obsolete, FreeCAD transitioned to Python 3 and Qt5. In most cases this transition was done without needing to break backwards compatibility.

Normally, the PySide module provides support for Qt4, while PySide2 provides support for Qt5. However, in FreeCAD, there is no need to use PySide2 directly, as a special PySide module is included to handle Qt5.

This PySide module is located in the Ext/ directory of an installation of FreeCAD compiled for Qt5.

/usr/share/freecad/Ext/PySide

This module just imports the necessary classes from PySide2, but places them in the PySide namespace. This means that in most cases the same code can be used with both Qt4 and Qt5, as long as it imports the single PySide module.

PySide2.QtCore -> PySide.QtCore
PySide2.QtGui -> PySide.QtGui
PySide2.QtSvg -> PySide.QtSvg
PySide2.QtUiTools -> PySide.QtUiTools

The only unusual aspect is that the PySide2.QtWidgets classes are placed in the PySide.QtGui namespace.

PySide2.QtWidgets.QCheckBox -> PySide.QtGui.QCheckBox

Real examples of PySide use

The examples of PySide are divided into 3 parts, differentiated by level of exposure to PySide, Python and the FreeCAD internals. The first page has an overview on PySide; the second and third pages are mostly code examples at different levels.

It is expected that these examples are useful to get started, and afterwards the user can consult other resources online, or the official documentation.

Documentation

There are some differences in handling of widgets in Qt4 (PySide) and Qt5 (PySide2). The programmer should be aware of these incompatibilities, and should consult the official documentation if something doesn't seem to work as expected in a given platform. Nevertheless, Qt4 is considered obsolete, so most development should target Qt5 and Python 3.

The PySide documentation refers to the Python-style classes; however, since Qt is originally a C++ library, the same information should be available in the corresponding C++ reference.