Re:[wxperl-users] Re: Wrapping wxArtProvider class

[mattia\.barbon\@libero\.it <mat...@li...>]

  Hello,

> I've made a lot of progress on my wrapping of wxArtProvider=
.  It is in
> fact almost complete. However, there's one nagging problem=
 regarding
> the perl callbacks.

  I'm sorry I couldn't answer before=
.

> I'm having issues with wxSize objects getting double deleted somew=
here
> in the call to wxArtProvider::CreateBitmap.  As near as I can tel=
l,
> what happens is:
> 1) Perl code calls Wx::ArtProvider::GetBitmap.=0D
=
> 2) XS code for Wx::ArtProvider::GetBitmap makes a wxSize object from=0D
=
> either the parameter passed, or from wxDefaultSize.
> 3) XS code calls=
 down to wxArtProvider::GetBitmap
> 4) In the guts of here, a call is ma=
de out to
> wxPlArtProvider::CreateBitmap, passing the wxSize object alo=
ng
> 5) The XS for wxPlArtProvider::CreateBitmap creates a Wx::Size obje=
ct
> to pass on to the perl code
> 6) The perl code does its thing
> 7=
) The Wx::Size object created in #5 goes out of scope, and the
> underly=
ing wxSize object gets destroyed
> 8) Call frames finish and we end up b=
ack in the XS for
> Wx::ArtProvider::GetBitmap
> 9) This code delets th=
e same underlying wxSize object again
> 10) Reams of warnings from glibc=
 about free()ing invalid pointers are
> emitted as this chain of events =
repeats.

 This looks plausible. There are workarounds for this in
ext=
/docview/XS/*.xs and ext/docview/cpp/*.h. I'll give more
precise indicat=
ions later.

> I can work around this by allocating a copy of the size =
on the heap in
> the XS for Wx::ArtProvider::CreateBitmap and then letti=
ng / assuming
> that it will be deleted by perl, but somehow this seems =
dirty.  But if
> it's the right way to go, then I guess the attached pat=
ch is okay.
> 
> Attached is a patch against 0.22 with my progress so f=
ar.  Other than
> the problem described here, it seems to work for all t=
he static
> functions of wxArtProvider, and for deriving your own provid=
er from
> Wx::PlArtProvider.  To demonstrate the latter, I added an artp=
rov
> sample based on the minimal sample from wxPerl and the artprov sam=
ple
> from wxWidgets.

  Great!
 
> As an aside, the build process f=
or my code, and for XS/PlWindow.xsp
> leaves the .h files they generate =
in cpp/ even after a make realclean.
>  What's the proper way to fix thi=
s?

  I fixed plwindow.h deletion in CVS. Add your file in
(IIRC) buil=
d/Wx/buid/ExtUtils/MakeMaker/Any_OS.pm.

HTH & thanks!
Mattia=0A=0A=0A=
=0A____________________________________________________________=0ALibero =
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