Viewprovider

Introduction

Viewproviders are classes that define the way objects will look like in the tree view and the 3D view, and how they will interact with certain graphical actions such as selection.

They complement the scripted objects. While the base class of the scripted object defines its data properties, the viewprovider defines it view properties. These view properties are not essential information of the object, as they only indicate superficial information like line width, line color, face color, etc. In a terminal only session, the viewprovider is not loaded because there will be no interface to manipulate those visible properties.

Like with data properties, view properties are accessible from the property editor.

Python view providers

The viewproviders classes usually include ViewProvider in their name. They are assigned on the ViewObject attribute of the base object.

In this example, we define two properties for the viewprovider, only if the properties don\'t already exist, and assign their default values. We also define the

# views/view_custom.py
class ViewProviderCustom:
    """Viewprovider of the custom object."""

    def __init__(self, vobj):
        self.Object = vobj.Object

        self._set_properties(vobj)
        vobj.Proxy = self

    def _set_properties(self, vobj):
        if not hasattr(vobj, "Pattern"):
            vobj.addProperty("App::PropertyEnumeration",
                             "Pattern",
                             "Custom",
                             "Defines a hatch pattern for this object.")
            vobj.Pattern = ["None", "diagonals", "cross", "brick"]

        if not hasattr(vobj, "PatternSize"):
            vobj.addProperty("App::PropertyFloat",
                             "PatternSize",
                             "Custom",
                             "Defines the size of the hatch pattern.")
            vobj.PatternSize = 1

    def onChanged(self, vobj, prop):
        if prop in "Pattern":
            self._set_pattern(vobj.Pattern)
        if prop in "PatternSize":
            self._set_size(vobj.PatternSize)

    def _set_pattern(self, pattern):
        ...

    def _set_size(self, size):
        ...

The normal workflow is to first add the object proxy class, for example,

import FreeCAD as App
import objects.custom as custom
import views.view_custom as view_custom

doc = App.newDocument()
obj = doc.addObject("Part::FeaturePython", "Custom")

custom.CustomObject(obj)

if App.GuiUp:
    view_custom.ViewProviderCustom(obj.ViewObject)

Custom icons

By implementing the getIcon method, you can specify the icon that will be shown in the tree view in the upper part of the combo view.

The return value can be the full path to an icon.

import os
some_path = "/home/user/.FreeCAD/custom_icons"

class ViewProviderCustom:
    ...

    def getIcon(self):
        return os.path.join(some_path, "my_icon.svg")

The relative path to an icon inside a compiled resource file.

import MyModule_rc.py

class ViewProviderCustom:
    ...

    def getIcon(self):
        return ":/icons/my_icon.svg"

A raw XPM icon, which is essentially ASCII art.

import MyModule_rc.py

class ViewProviderCustom:
    ...

    def getIcon(self):
        return """
               /* XPM */
               static char *Some_icon_xpm[] = {
               /* columns rows colors chars-per-pixel */
               "16 16 3 1 ",
               "  c None",
               ". c #D71414",
               "+ c #AA1919",
               /* pixels */
               "                ",
               "  +          +  ",
               " +.+        +.+ ",
               "  +.+      +.+  ",
               "   +        +   ",
               "      ++++      ",
               "     +....+     ",
               "     +...++     ",
               "     +..+++     ",
               "     +.++.+     ",
               "      ++++      ",
               "   +        +   ",
               "  +.+      +.+  ",
               " +.+        +.+ ",
               "  +          +  ",
               "                "
               };
               """

See various examples in Custom icon in tree view.

⏵ documentation index > Developer Documentation > Python Code > Viewprovider

This page is retrieved from https://github.com/FreeCAD/FreeCAD-documentation/blob/main/wiki/Viewprovider.md