Workbench creation

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This page will show you how to add a new workbench to the FreeCAD interface. Workbenches are containers for FreeCAD commands. They can be coded in python, in C++, or in a mix of both, which has the advantage to ally the speed of C++ to the flexibility of python. In all cases, though, your workbench will be launched by a set of two python files.

The workbench structure

Basically it is simple: You need a folder, with any name you like, placed in the Mod directory, with an Init.py file, and, optionally an InitGui.py file. The Init file is executed when FreeCAD starts, always, and the InitGui.py file is executed immediately after, but only when FreeCAD starts in GUI mode, not in console mode. That's all it needs for FreeCAD to find your workbench at startup and add it to its interface.

Inside those files you can do whatever you want. Usually they are used like this:

  • In the Init.py file you just add a couple of things used even when FreeCAD works in console mode, for example the file importers and exporters
  • In the InitGui.py file you usually define a workbench, which contains a name, an icon, and a series of FreeCAD commands (see below). That workbench also defines functions that are executed when FreeCAD loads (you try to do as little as possible there, so you don't slow down the startup), another that gets executed when the workbench is activated (that's where you'll do most of the work), and a third one when the workbench is deactivated (so you can remove things if needed).

A typical Init.py file

# FreeCAD init script of XXX module  

#***************************************************************************
#*   (c) John Doe john@doe.com 2015                                        *   
#*                                                                         *
#*   This file is part of the FreeCAD CAx development system.              *
#*                                                                         *
#*   This program is free software; you can redistribute it and/or modify  *
#*   it under the terms of the GNU Lesser General Public License (LGPL)    *
#*   as published by the Free Software Foundation; either version 2 of     *
#*   the License, or (at your option) any later version.                   *
#*   for detail see the LICENCE text file.                                 *
#*                                                                         *
#*   FreeCAD is distributed in the hope that it will be useful,            *
#*   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
#*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
#*   GNU Lesser General Public License for more details.                   *
#*                                                                         *
#*   You should have received a copy of the GNU Library General Public     *
#*   License along with FreeCAD; if not, write to the Free Software        *
#*   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
#*   USA                                                                   *
#*                                                                         *
#***************************************************************************/

FreeCAD.addImportType("My own format (*.own)","importOwn")
FreeCAD.addExportType("My own format (*.own)","importOwn")

You can choose any license you like for your workbench, but be aware that if you wish to see your workbench integrated into and distributed with the FreeCAD source code at some point, it needs to be LGPL2+ like the example above. The FreeCAD.addImportType() and addEXportType() functions allow you to give the name and extension of a file type, and a python module responsible for its import. In the example above, an "importOwn.py" module will handle .own files. See Code snippets for more examples.

A typical InitGui.py file

class MyWorkbench (Workbench):

    MenuText = "My Workbench"
    ToolTip = "A description of my workbench"
    Icon = """paste here the contents of a 16x16 xpm icon"""

    def Initialize(self):
        "This function is executed when FreeCAD starts"
        import MyModuleA, MyModuleB # import here all the needed files that create your FreeCAD commands
        self.list = ["MyCommand1, MyCommand2"] # A list of command names created in the line above
        self.appendToolbar("My Commands",self.list) # creates a new toolbar with your commands
        self.appendMenu("My New Menu",self.list) # creates a new menu
        self.appendMenu(["An existing Menu","My submenu"],self.list) # appends a submenu to an existing menu

    def Activated(self):
        "This function is executed when the workbench is activated"
        return

    def Deactivated(self):
        "This function is executed when the workbench is deactivated"
        return

    def ContextMenu(self, recipient):
        "This is executed whenever the user right-clicks on screen"
        # "recipient" will be either "view" or "tree"
        self.appendContextMenu("My commands",self.list) # add commands to the context menu

    def GetClassName(self): 
        # this function is mandatory
        return "Gui::PythonWorkbench"
       
Gui.addWorkbench(MyWorkbench())

Other than that, you can do anything you want: You could put your whole workbench code inside the InitGui.py if you want, but it is usually more convenient to place the different functions of your workbench in separate files. So those files are smaller and easier to read. Then you import those files into your InitGui.py file. You can organize those files the way you want, a good example is one for each FreeCAD command you add.

FreeCAD commands

FreeCAD commands are the basic building block of the FreeCAD interface. They can appear as a button on toolbars, and as a menu entry in menus. But it is the same command. A command is a simple python class, that must contain a couple of predefined attributes and functions, that define the name of the command, its icon, and what to do when the command is activated.

A typical command definition

class My_Command_Class():
    """My new command"""

    def GetResources(self):
        return {'Pixmap'  : 'My_Command_Icon', # the name of a svg file available in the resources
                'Accel' : "Shift+S", # a default shortcut (optional)
                'MenuText': "My New Command"
                'ToolTip' : "What my new command does"}

    def Activated(self):
        "Do something here"
        return

    def IsActive(self):
        """Here you can define if the command must be active or not (greyed) if certain conditions
        are met or not. This function is optional."""
        return True

FreeCADGui.addCommand('My_Command',My_Command_Class())