CreateAccessible not virtual in latest snapshot

[DietmarSchwertberger]

Operating system: Windows 11, 64 bit
wxPython version & source: latest 4.3 snapshots, e.g. wxpython-4.3.0a16024+b2b09702-cp312-cp312-win_amd64.whl
Python version & source: stock 3.12 or 3.14

Description of the problem:

The wxWidgets 3.3 branch adds wxWindow->CreateAccessible() and wxWindow->GetOrCreateAccessible() to interface/wx/window.h.
With wxPython PR #2618 and PR #2515 wx.Window.GetOrCreateAccessible should call the virtual CreateAccessible to allow a Python class to provide an accessibility handler on demand by overriding this virtual method.

It seems that this is not working with the snapshot. Probably the C++ implementation of CreateAccessible is being called and this returns None.
With my own build of the current master branch, it's working fine. (I'm just using the standard commands python build.py dox etg --nodoc sip build).

The virtual method is only created in tweaker_tools.py if Windows is detected by
isWindows = sys.platform.startswith('win')
Could it be that this check does not work with the snapshot build process?

The output of the example code below:
With the snapshot build:

D:\Python\Python312-64_wx430>python AccessibleFrameMin.py
GetOrCreateAccessible(): None

The correct output with my own build (Visual Studio 2022):

D:\Python\Python312-64_wxgit>python AccessibleFrameMin.py
GetOrCreateAccessible(): <__main__.MyAcc object at 0x000002731643C9E0>

Code Example (click to expand)

import wx


class MyAcc(wx.Accessible):
    pass


# this does override CreateAccessible to return a custom accessibility handler
class MyAccessibleTextCtrl(wx.TextCtrl):
    def CreateAccessible(self):
        return MyAcc(self)


class MainFrame(wx.Frame):
    def __init__(self, parent, id=wx.ID_ANY, title=''):
        wx.Frame.__init__(self, parent, id, title)
        self.panel = wx.Panel(self, wx.ID_ANY)

        self.text_ctrl = MyAccessibleTextCtrl(self.panel, wx.ID_ANY, "")


class MyApp(wx.App):
    def OnInit(self):
        self.frame = MainFrame(None, wx.ID_ANY, "")
        self.SetTopWindow(self.frame)
        self.frame.Show()
        return True


# call GetOrCreateAccessible and print the result:

app = MyApp(0)
print("GetOrCreateAccessible():", app.frame.text_ctrl.GetOrCreateAccessible() )
app.MainLoop()

[swt2c]

Yeah, so the reason is that the etg process is run on a Linux host during the snapshot builds. We'll have to think about another way to do this (ideally, we don't have to go back to building the etg / sip stuff separately per OS).

[DietmarSchwertberger]

Well, I took the code for isWindows from build.py. Did not expect this to fail...

I have just uploaded a draft PR to check the output from CI if CreateAccessible is unconditionally added to publicWindowVirtuals.

This is the error message from the Ubuntu build:

  [ 10/963] Compiling sip/cpp/sip_corewxWindowDestroyEvent.cpp
  [ 11/963] Compiling sip/cpp/sip_corewxListBox.cpp
  [ 12/963] Compiling sip/cpp/sip_corewxEvent.cpp
  [ 13/963] Compiling sip/cpp/sip_corewxCloseEvent.cpp
  ../../../../sip/cpp/sip_corewxListBox.cpp:145:21: error: ‘wxAccessible* sipwxListBox::CreateAccessible()’ marked ‘override’, but does not override
    145 |     ::wxAccessible* CreateAccessible() SIP_OVERRIDE;
        |                     ^~~~~~~~~~~~~~~~
  ../../../../sip/cpp/sip_corewxListBox.cpp: In member function ‘wxAccessible* sipwxListBox::CreateAccessible()’:
  ../../../../sip/cpp/sip_corewxListBox.cpp:652:29: error: ‘CreateAccessible’ is not a member of ‘wxListBox’
    652 |         return ::wxListBox::CreateAccessible();
        |                             ^~~~~~~~~~~~~~~~
  ../../../../sip/cpp/sip_corewxListBox.cpp: In function ‘PyObject* meth_wxListBox_CreateAccessible(PyObject*, PyObject*)’:
  ../../../../sip/cpp/sip_corewxListBox.cpp:2880:60: error: ‘class wxListBox’ has no member named ‘CreateAccessible’
   2880 |             sipRes = (sipSelfWasArg ? sipCpp->::wxListBox::CreateAccessible() : sipCpp->CreateAccessible());
        |                                                            ^~~~~~~~~~~~~~~~
  ../../../../sip/cpp/sip_corewxListBox.cpp:2880:89: error: ‘class wxListBox’ has no member named ‘CreateAccessible’
   2880 |             sipRes = (sipSelfWasArg ? sipCpp->::wxListBox::CreateAccessible() : sipCpp->CreateAccessible());
        |                                                                                         ^~~~~~~~~~~~~~~~

  Waf: Leaving directory `/tmp/pip-req-build-fm0m2ef9/build/waf/3.10/gtk3'
  Build failed
   -> task in '_core' failed with exit status 1 (run with -v to display more information)

And from the macos build:

 [ 11/963] Compiling sip/cpp/sip_corewxWindowDestroyEvent.cpp
    [ 12/963] Compiling sip/cpp/sip_corewxEvent.cpp
    ../../../sip/cpp/sip_corewxListBox.cpp:145:40: error: only virtual member functions can be marked 'override'
        ::wxAccessible* CreateAccessible() SIP_OVERRIDE;
                                           ^~~~~~~~~~~~
    ../../../sip/siplib/sip.h:114:25: note: expanded from macro 'SIP_OVERRIDE'
    #define SIP_OVERRIDE    override
                            ^
    ../../../sip/cpp/sip_corewxListBox.cpp:652:16: error: no member named 'CreateAccessible' in 'wxListBox'; did you mean simply 'CreateAccessible'?
            return ::wxListBox::CreateAccessible();
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                   CreateAccessible
    ../../../sip/cpp/sip_corewxListBox.cpp:644:31: note: 'CreateAccessible' declared here
    ::wxAccessible* sipwxListBox::CreateAccessible()
                                  ^
    ../../../sip/cpp/sip_corewxListBox.cpp:2880:89: error: no member named 'CreateAccessible' in 'wxListBox'
                sipRes = (sipSelfWasArg ? sipCpp->::wxListBox::CreateAccessible() : sipCpp->CreateAccessible());
                                                                                    ~~~~~~  ^
    ../../../sip/cpp/sip_corewxListBox.cpp:2880:60: error: no member named 'CreateAccessible' in 'wxListBox'
                sipRes = (sipSelfWasArg ? sipCpp->::wxListBox::CreateAccessible() : sipCpp->CreateAccessible());
                                          ~~~~~~               ^
    4 errors generated.

[swt2c]

Yes, those are the errors I would expect as CreateAccessible only exists in wxWidgets for MSW.

We need to figure out how to add CreateAccessible to wxPython unconditionally, but in the C++ code, guard it from being compiled on Linux and macOS. We need to do something like this:
https://github.com/wxWidgets/Phoenix/blob/master/etg/_glcanvas.py#L131

But figure out some place to do it for all Window classes.

[DietmarSchwertberger]

Actually etg/window.py has such code:

    # wxAccessbile is MSW only. Provide a NotImplemented fallback for the
    # other platforms.

    c.find('CreateAccessible').factory = True
    c.find('CreateAccessible').setCppCode("""\
        #if wxUSE_ACCESSIBILITY
            return self->CreateAccessible();
        #else
            wxPyRaiseNotImplemented();
            return NULL;
        #endif
        """)

What is this doing if CreateAccessible does not exist on the platform?
In ext/wxWidgets/include/wx/window.h it's only added conditionally:

#if wxUSE_ACCESSIBILITY
    // Override to create a specific accessible object.
    virtual wxAccessible* CreateAccessible() { return nullptr; }
[...]
#endif

[swt2c]

That is only doing it for wxWindow, though. It needs to be done for all subclasses too. Working on a solution...

[swt2c]

Of course, I ran into a really strange sip bug while implementing the fix... :(