Code snippets

This page contains examples, pieces, chunks of FreeCAD python code collected from users experiences and discussions on the forums. Read and use it as a start for your own scripts...

A typical InitGui.py file
Every module must contain, besides your main module file, an InitGui.py file, responsible for inserting the module in the main Gui. This is an example of a simple one.

A typical module file
This is an example of a main module file, containing everything your module does. It is the Scripts.py file invoked by the previous example. You can have all your custom commands here.

Import a new filetype
Making an importer for a new filetype in FreeCAD is easy. FreeCAD doesn't consider that you import data in an opened document, but rather that you simply can directly open the new filetype. So what you need to do is to add the new file extension to FreeCAD's list of known extensions, and write the code that will read the file and create the FreeCAD objects you want:

This line must be added to the InitGui.py file to add the new file extension to the list:

Then in the Import_Ext.py file:

Adding a line
A line simply has 2 points.

Adding a polygon
A polygon is simply a set of connected line segments (a polyline in AutoCAD). It doesn't need to be closed.

Adding and removing an object to a group
Note: You can even add other groups to a group...

Accessing and changing representation of an object
Each object in a FreeCAD document has an associated view representation object that stores all the parameters that define how the object appear, like color, linewidth, etc...

Observing mouse events in the 3D viewer via Python
The Inventor framework allows to add one or more callback nodes to the scenegraph of the viewer. By default in FreeCAD one callback node is installed per viewer which allows to add global or static C++ functions. In the appropriate Python binding some methods are provided to make use of this technique from within Python code.

Now, pick somewhere on the area in the 3D viewer and observe the messages in the output window. To finish the observation just call

The following event types are supported
 * SoEvent -- all kind of events
 * SoButtonEvent -- all mouse button and key events
 * SoLocation2Event -- 2D movement events (normally mouse movements)
 * SoMotion3Event -- 3D movement events (normally spaceball)
 * SoKeyboradEvent -- key down and up events
 * SoMouseButtonEvent -- mouse button down and up events
 * SoSpaceballButtonEvent -- spaceball button down and up events

The Python function that can be registered with addEventCallback expects a dictionary. Depending on the watched event the dictionary can contain different keys. For all events it has the keys: For all button events, i.e. keyboard, mouse or spaceball events For keyboard events: For mouse button event For spaceball events: And finally motion events:
 * Type -- the name of the event type i.e. SoMouseEvent, SoLocation2Event, ...
 * Time -- the current time as string
 * Position -- a tuple of two integers, mouse position
 * ShiftDown -- a boolean, true if Shift was pressed otherwise false
 * CtrlDown -- a boolean, true if Ctrl was pressed otherwise false
 * AltDown -- a boolean, true if Alt was pressed otherwise false
 * State -- A string 'UP' if the button was up, 'DOWN' if it was down or 'UNKNOWN' for all other cases
 * Key -- a character of the pressed key
 * Button -- The pressed button, could be BUTTON1, ..., BUTTON5 or ANY
 * Button -- The pressed button, could be BUTTON1, ..., BUTTON7 or ANY
 * Translation -- a tuple of three floats
 * Rotation -- a quaternion for the rotation, i.e. a tuple of four floats

Manipulate the scenegraph in Python
It is also possible to get and change the scenegraph in Python. Therefore you have to have the 'pivy' module -- a Python binding for Coin.

The Python API of pivy is created by using the tool SWIG. As we use in FreeCAD some self-written nodes you cannot create them directly in Python. However, it is possible to create a node by its internal name. An instance of the type 'SoFCSelection' can be created with

Adding and removing objects to/from the scenegraph
Adding new nodes to the scenegraph can be done this way. Take care of always adding a SoSeparator to contain the geometry, coordinates and material info of a same object. The following example adds a red line from (0,0,0) to (10,0,0):

To remove it, simply issue:

Adding custom widgets to the interface
You can create custom widgets with Qt designer, transform them into a python script, and then load them into the FreeCAD interface with PyQt4.

The python code produced by the Ui python compiler (the tool that converts qt-designer .ui files into python code) generally looks like this (it is simple, you can also code it directly in python):

Then, all you need to do is to create a reference to the FreeCAD Qt window, insert a custom widget into it, and "transform" this widget into yours with the Ui code we just made: