[wxPython] bug in 'wxPyTypeCast' for 'wxTreeCtrl' ??

wxPython Users
1

BUG IN WXWINDOWS-BINDING TO PYTHON ?

hi!

i'm a c++ professional,

but i consider using python and wxwindows for my win32 gui tools.
i find them very powerfull, but recently a bug (?) stopped me:

i construct some gui-controls in a function, an so i can not access them
directly.

i need to find them with 'FindWindowById' and 'wxPyTypeCast'
for wxButton and wxSlider and much other stuff this is no problem,
but it does not works for wxTreeCtrl.

sample:

        PlaceTree(self) #constructs a tree
                
        self.tree = wxPyTypeCast( self.FindWindowById( 151515 ),
"wxTreeCtrl" )
        self.tree.Unselect() #this crashes at compiletime
        self.tree.AddRoot("ral") #this too
        
        self.tree = wxPyTypeCast( self.FindWindowById( 161616 ), "wxButton"
)
        self.tree.Enable(false) #this works fine
        
the errormessage is as follows:

  File "python20\wxPython\controls2.py", line 746, in Unselect
        val = apply(controls2c.wxTreeCtrl_Unselect,(self,) + _args, _kwargs)
        TypeError: Type error in argument 1 of wxTreeCtrl_Unselect, Expected
_wxPyTreeCtrl_p.
          
if i call AddRoot() directly in the 'PlaceTree' function, where the tree
gets constructed,
everything is fine.

so i think there must be a bug in 'FindWindowById', or more probably in
'wxPyTypeCast'

exactly the same error appears for the button, if i exchange "wxButton" to
"wxTreeCtrl".
(cast to a wrong type)

can you help me with this?
i can not debug this code.
but i dont want to use mfc or tcl..
inserting my c++ code in python seems much better.

below is the TypCast function from wx.py

···

#----------------------------------------------------------------------
# This helper function will take a wxPython object and convert it to
# another wxPython object type. This will not be able to create objects
# that are derived from wxPython classes by the user, only those that are
# actually part of wxPython and directly corespond to C++ objects.
#
# This is useful in situations where some method returns a generic
# type such as wxWindow, but you know that it is actually some
# derived type such as a wxTextCtrl. You can't call wxTextCtrl specific
# methods on a wxWindow object, but you can use this function to
# create a wxTextCtrl object that will pass the same pointer to
# the C++ code. You use it like this:
#
# textCtrl = wxPyTypeCast(window, "wxTextCtrl")
#
#
# WARNING: Using this function to type cast objects into types that
# they are not is not recommended and is likely to cause your
# program to crash... Hard.
#

def wxPyTypeCast(obj, typeStr):
    if hasattr(obj, "this"):
        newPtr = ptrcast(obj.this, typeStr+"_p")
    else:
        newPtr = ptrcast(obj, typeStr+"_p")
    theClass = globals()[typeStr+"Ptr"]
    theObj = theClass(newPtr)
    if hasattr(obj, "this"):
        theObj.thisown = obj.thisown
    return theObj

Another minor problem is:

if i use wxStaticBoxSizers, their client-area is not
correctly updated, if directly embedded into a wxFrame.
(the background from UNDER the wxFrame shines trought partialy)

if embedded into a wxDialog, everything is fine.

this bugs rise on win nt4.0 (with the new comctrl.dll)
not tested on win95

Matthias

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2

i need to find them with 'FindWindowById' and 'wxPyTypeCast'
for wxButton and wxSlider and much other stuff this is no problem,
but it does not works for wxTreeCtrl.

The wxTreeCtrl class in the python interface is actually wrapps a C++ class named wxPyTreeCtrl, which handles the redirections for the OnCompareItems virtual method. Because of this renaming the internal swig typename is one thing and the visible class name is another, so wxPyTypeCast doesn't work right. Robert R. recently discovered this and came up with the following workaround. The newest wxDesigner will generate a getter for a tree control like this instead of using wxPyTypeCast directly:

    def GetTreectrl(self):
        window = self.FindWindowById(ID_TREECTRL)
        if hasattr(window, "this"):
            newPtr = ptrcast(window.this, "wxPyTreeCtrl_p")
        else:
            newPtr = ptrcast(window, "wxPyTreeCtrl_p")
        theClass = globals()["wxTreeCtrlPtr"]
        theObj = theClass(newPtr)
        if hasattr(window, "this"):
            theObj.thisown = window.thisown
        return theObj

Another minor problem is:

if i use wxStaticBoxSizers, their client-area is not
correctly updated, if directly embedded into a wxFrame.
(the background from UNDER the wxFrame shines trought partialy)

if embedded into a wxDialog, everything is fine.

This is a known problem and the workaround is to always use a wxPanel or wxDialog under the wxStaticBox.

···

--
Robin Dunn
Software Craftsman
robin@AllDunn.com Java give you jitters?
http://wxPython.org Relax with wxPython!

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