The FreeCAD source code/de

DerFreeCAD Quellcode wird mit git verwaltet, ist public, offen und unter der LGPL Lizenz erhältlich. Er kann durch jederman kopiert, heruntergeladen, gelesen, analysiert, weiterverteilt und modifiziert werden. Wenn gewünschte Änderungen in den offiziellen Code einfließen sollen, müssen die selbst erstellten Änderungen durch FreeCAD Entwickler genehmigt werden. Es ist daher notwendig zunächst die Absichten und Ideen im Forum zu diskutieren, um zu verhindern, dass die vorzunehmenden Änderungen aus Gründen abgewiesen werden, die man selbst vorher nicht erkennt.

Es folgen einige Hinweise und nützliche Informationen zur Einführung, wenn Interesse am FreeCAD-Code besteht.


 * Der FreeCAD-Code ist hauptsächlich in C++ programmiert, stützt sich aber stark auf Python. Ein sehr großer Teil seiner Funktionalität bietet Verbindungen zu Python, und ist Teil der Kernphilosophie der FreeCAD Entwicklung permanent Zugriff zu jeder neuen Funktion, die in C++ einfließt (implementiert wird), über Python zu bieten. Um dies zu erreichen, wird CPython (das C steht für Werkzeuge, die durch Python selbst zur Verfügung gestellt werden) und besonders PyCXX intensiv für FreeCAD genutzt. Viele Vorlagen und selbst erstellte Werkzeuge werden ebenfalls im FreeCAD-Code zur Verfügung gestellt, um das Erstellen von passenden Python Verbindungen zu erleichtern. Einige wichtige Teile des FreeCAD-Codes sind vollständig in Python erstellt.


 * The FreeCAD source code is fully multi-platform, and great care is taken to allow to use the application on a biggest possible number of platforms and configurations, and not put existing users in difficult situations. Therefore, as most as possible, new versions of needed components are avoided while they are not widely and easily available on all platforms, and backwards compatibility (the ability to open a file produced with a new version of FreeCAD on an older version) is an important priority.


 * Almost all the functionality of FreeCAD is separated in two different parts, named App and Gui. This separation is reflected everywhere in the files structure of the source code. App contains all the functionality that needs to run in pure console mode (no GUI). As FreeCAD can be compiled and run without its Graphical User Interface, the code in App is independent of any GUI-related library. Gui contains all the code needed to run in GUI mode, and is built around the App functionality.


 * Most of FreeCAD's functionality is implemented in Modules. FreeCAD without its module is a simple container window that can just open and save a file. All the geometry tools and workbenches are implemented in Modules. Modules can be written in C++, in Python, or combining the best of the two worlds, can be hybrid C++/Python modules, where solid, core functionality is programmed in C++ while end-user tools are made in Python and are therefore much easier to extend and adapt by FreeCAD users. Each module usually defines and creates a Workbench in the FreeCAD interface, when used in GUI mode, usually with the same name, but it is not mandatory for modules to contain a workbench.


 * FreeCAD modules often depend on other modules. Most modules that use solid geometry depend on the Part module, which is the most fundamental module of FreeCAD, and implements most of the interfacing with OpenCasCade. Although other module can use OpenCasCade functionality directly, they often rely on higher-level functions provided by Part.


 * Modules are always initialized from Python. Even if they are written fully in C++, they always contain a minimal Python/CPython structure.


 * FreeCAD is an avid user of other open-source libraries. Besides Python and Qt, used by the core and almost all of the modules, the two heavyweight libraries used throughout most modules are OpenCasCade Technology and Coin3D. OpenCasCade is used to create and manage all the solid geometry of FreeCAD, while coin3D is used to manage the 3D view. OpenCascade is used mainly in the App world, and coin3D exclusively in the Gui world. A basic understanding of OpenCasCade is fundamental to do any geometry-related work with FreeCAD. More specific modules make use of more specific libraries, and since there are usually no restrictions on that point apart from these libraries to be easily available on all platforms, the list of dependencies of a full FreeCAD installation with all its modules can be quite large.


 * FreeCAD's document objects, which are all the objects contained in a FreeCAD document, are what appear in the Tree View in the GUI and in FreeCAD.ActiveDocument.Objects in Python. They may or may not have any geometrical data, and may or may not show anything in the 3D view. They are always separated in App and Gui parts. The Gui part is not loaded when running in console mode. Standard geometrical objects, such as those found in Part or PartDesign, have their OpenCasCade-based geometry defined in their App counterpart, while the Gui counterpart (also usually called "View Provider") is responsible for creating a coin3D representation of that geometry, which will be inserted into the main coin3D scene graph of the 3D view.


 * The basic directory structure of the source code is organized like this:
 * App: contains the FreeCAD console-mode application, defines basic structures and base classes for document objects, that are used by modules to build their own.
 * Base: contains core functionality commonly used everywhere in FreeCAD: 3D vectors, units, matrices, placements, etc.
 * Gui: contains the FreeCAD GUI-mode application, defines the 3D view, contains many tools and functions to be used by workbenches to interact with the interface and with the 3D view, defines base classes for view providers.
 * Doc: contains mainly an all-in-one Qt help file generated from this wiki.
 * Mod: contains all the modules, themselves further separated into App and Gui (except for python modules, which don't always follow that rule so clearly).

Related

 * Source Code Management
 * The Power users hub contains a lot of documentation about modules, OpenCasCade and Coin3D, mainly for the Python programmer. However, as the functionality is similar, these pages will be of interest to the C++ programmer as well.