[Bug] even if the Group property is set readonly, dragging is allowed

[flachyjoe]

Hi,
Context:

Code: Select all

class StaticGroup:
    def __init__(self, obj, children):

        obj.Proxy = self

        self.Type = "MyObject"
        self.children = children

        obj.Group = children
        obj.setPropertyStatus('Group', 'ReadOnly')

obj = App.ActiveDocument.addObject('App::DocumentObjectGroupPython', 'MyStaticGroup')
StaticGroup(obj, children)

Expected result:
Dragging an object in the StaticGroup shouldn't change the Group property and fail

Observed result:
Dragging change the Group property, an object can be add or a child can be removed.

Workaround:

Code: Select all

class StaticGroup:
    def __init__(self, obj, children):

        obj.Proxy = self

        self.Type = "MyObject"
        self.children = children

        obj.Group = children

    def onChanged(self, fp, prop):
        if str(prop) == 'Group':
            fp.Group = self.children

OS: Ubuntu 21.04 (XFCE/xubuntu)
Word size of FreeCAD: 64-bit
Version: 0.20.25207 (Git)
Build type: Unknown
Branch: master
Hash: e73ddda1b704fb602e1528efbf860862f51b9a3b
Python version: 3.9.5
Qt version: 5.15.2
Coin version: 4.0.0
OCC version: 7.5.2
Locale: French/France (fr_FR)

[ickby]

Read-only for a property does only apply for the property editor. It does not prevent any programmatic change of the property, neither by python, c++ or even other UI elements like Dialogs etc.

Drag and drop as a UI feature is controlled by the viewprovider. There you can define if drag and drop is supported, and what to do on a drop. For this override the filling functions:

Code: Select all

canDragObjects() --> return true/false for enable/disable
canDragObject(obj) --> same for individual objects
dragObject(obj) --> when object is draged by the user

As a side note: if you want to make a property really unchangeable, you need to set it to immutable (possible since 0.19). If I remember this works by using

Code: Select all

setPropertyStatus

. the method has good documentation on how-to do it.
But I would expect strange behaviour in the sense, that the UI feedback would show the user to allow drag and drop, but nothing would be changed and only an error printed.

[flachyjoe]

Thank you ickby for the clarification.

UI reacts anyway on read-only properties with removing of spin buttons and other three-dots ones and blocks text editing so it's disappointing to allow drag and drop.

[ickby]

Drag and drop is a universal implementarion, detailed by the document objects. It has no idea, what a group property is, or how it influences drag and drop. So it is understandable that it cannot react on the read only status.