App FeaturePython

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Introduction

An Feature.svg App FeaturePython object, or formally an App::FeaturePython, is a simple instance of the App DocumentObject in Python.

This is a simple object that by default doesn't have many properties, for example, no placement nor topological shape. This object is for general purpose use; depending on the properties that are assigned to it, it can be used to manage different types of data.

FreeCAD core objects.svg

Simplified diagram of the relationships between the core objects in the program. The App::FeaturePython class is a simple implementation of the App::DocumentObject that can be used for any purpose, as it doesn't have a TopoShape by default.


Usage

The App FeaturePython is an internal object, so it cannot be created from the graphical interface. It is meant to be sub-classed by classes that will handle different types of data.

See Scripting for more information.

Properties

An App FeaturePython (App::FeaturePython class) is derived from the basic App DocumentObject (App::DocumentObject class), therefore it shares all the latter's properties.

In addition to the properties described in App DocumentObject, the FeaturePython has a basic view provider, so it does appear in the tree view.

See Property for all property types that scripted objects can have.

These are the properties available in the property editor. Hidden properties can be shown by using the Show all command in the context menu of the property editor.

Data

Base

  • Data (hidden)Proxy (PythonObject): a custom class associated with this object.
  • DataLabel (String): the user editable name of this object, it is an arbitrary UTF8 string.
  • Data (hidden)Label2 (String): a longer, user editable description of this object, it is an arbitrary UTF8 string that may include newlines. By default, it is an empty string "".
  • Data (hidden)Expression Engine (ExpressionEngine): a list of expressions. By default, it is empty [].
  • Data (hidden)Visibility (Bool): whether to display the object or not.

View

These properties correspond to the basic properties of the base viewprovider, Gui::ViewProviderDocumentObject, that is inherited by all viewproviders in the software.

Base

  • View (hidden)Proxy (PythonObject): a custom view provider class associated with this object. This property only exist for those classes that are able to assign a custom class.

Display Options

  • ViewDisplay Mode (Enumeration): it is empty by default.
  • ViewShow In Tree (Bool): it defaults to true, in which case the object will appear in the tree view; otherwise, the object will be hidden in the tree view. Once an object in the tree is invisible, you can see it again by opening the context menu over the name of the document (right-click), and selecting CheckBoxTrue.svg Show hidden items. Then the hidden item can be chosen and ViewShow In Tree can be switched back to true.
  • ViewVisibility (Bool): it defaults to true, in which case the object will be visible in the 3D view if it has a Shape, otherwise it will be invisible. By default this property can be toggled on and off by selecting the object, and pressing the Space bar in the keyboard.

Selection

  • ViewOn Top When Selected (Enumeration): it controls the way in which the selection occurs in the 3D view if the object has a Shape, and there are many objects partially covered by others. It defaults to Disabled, meaning that no special highlighting will occur; Enabled means that the object will appear on top of any other object when selected; Object means that the object will appear on top only if the entire object is selected in the tree view; Element means that the object will appear on top only if a subelement (vertex, edge, face) is selected in the 3D view.
  • ViewSelection Style (Enumeration): it controls the way the object is highlighted if it has a Shape. If it is Shape, the entire shape (vertices, edges, and faces) will be highlighted in the 3D view; if it is BoundBox a bounding box will appear surrounding the object and will be highlighted.

Scripting

See also: FreeCAD Scripting Basics, and scripted objects.

See Part Feature for the general information on adding objects to the program.

An App FeaturePython is created with the addObject() method of the document.

import FreeCAD as App

doc = App.newDocument()
obj = App.ActiveDocument.addObject("App::FeaturePython", "Name")
obj.Label = "Custom label"

For example, the Draft Text, Draft Dimension, and Working plane proxy elements of the Draft Workbench are App::FeaturePython objects with a custom icon and additional properties. They hold data but not an actual Part TopoShape.

If the desired object should have a placement, a shape, an attachment, or other complex properties, it is better to create one of the more complex classes, for example, App GeoFeature, Part Feature, or Part Part2DObject.