[wxPython-users] CustomTreeCtrl windows added via SetWindow aren't properly handled

[Andrea Gavana]

Hi Mike,

On 7/17/07, Mike Rooney wrote:
> Great! I noticed DeleteWindow on a GenericTreeItem also has the same
> issue but in reverse. The item never gets /removed /from the tree's
> _itemWithWindow, so later it will crash when you remove the item if you
> had previously properly added the window (say via SetItemWindow, or
> passed it in initially on item creation). From 'Delete' in
> CustomTreeCtrl [~#3433]:
>
>        # Remove the item with window
>        if item in self._itemWithWindow:
>            wnd = item.GetWindow()
>            wnd.Hide()
>
> If you previously used item.DeleteWindow, item.GetWindow will return
> None, and you will get an exception on the next line that NoneType has
> no attribute Hide. So I guess we also need a DeleteItemWindow in
> CustomTreeCtrl which removes the item from _itemWithWindow.
>
> Once those are there, SetWindow and DeleteWindow on a GenericTreeItem
> should probably not be "public" anymore, right (have underscores
> appended to the method names)?
>
> Though it seems a shame to lose these methods on the items themselves.
> One of the nicest things about going from a TreeCtrl to a CustomTreeCtrl
> for me was being able to call so many methods right on the tree items
> themselves. You can just pass them around as you please and perform many
> useful operations without worrying about also having the tree object
> available. Though, I don't see any particularly elegant way to
> accomplish this. Oh well!

Yes, I do see the same problem, and at the moment I can't think about
a solution off the top of my head... but I will think about it.
However, if I had to choose, I would go with the implementation of
SetItemWindow and DeleteItemWindow on CustomTreeCtrl moving the
GenericTreeItem to "private" methods (I am shivering on thoughts about
C++ :-D ).

> PS - Is the below method how you implemented SetItemWindow? It seems to
> work well but I don't want to make any silly mistakes.
>
>    def SetItemWindow(self, item, wnd):
>        """Sets the window for the given item"""
>
>        if wnd is not None:
>            self._hasWindows = True
>            if not item in self._itemWithWindow:
>                self._itemWithWindow.append(item)
>
>        item.SetWindow(wnd)

Almost perfect, except one thing: what happens if the item already
have a window? I would probably modify it to something like:

    def SetItemWindow(self, item, wnd):
        """Sets the window for the given item"""

        if wnd is not None:
            self._hasWindows = True
            if not item in self._itemWithWindow:
                self._itemWithWindow.append(item)
            else:
                oldWnd = item.GetWindow()
                oldWnd.Destroy()

        item.SetWindow(wnd)

More or less, it should be ok (not tested). I still have to send a
patch to Robin: the summer holidays left almost no one in the office
and I am struggling to keep the pace at work :-D :-D

Andrea.

"Imagination Is The Only Weapon In The War Against Reality."
http://xoomer.alice.it/infinity77/