Message-ID: <43412404.3090002 at irisa.fr>
Date: Mon, 03 Oct 2005 14:28:52 +0200
From: Sebastien Ferre <ferre at irisa.fr>
Organization: IRISA
MIME-Version: 1.0
To: lablgtk at math.nagoya-u.ac.jp
Cc: Olivier Andrieu <oandrieu at nerim.net>
Subject: Re: GTree: delaying the computation of a pixbuf upon visibility
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Olivier Andrieu wrote:
>  Sebastien Ferre [Monday 3 October 2005] :
>  >
>  > Olivier Andrieu wrote:
>  > >  Sebastien Ferre [Friday 30 September 2005] :
>  > >  >
>  > >  > Hi,
>  > >  > 
>  > >  > Olivier Andrieu wrote:
>  > >  > >  Sebastien Ferre [Wednesday 28 September 2005] :
>  > >  > >  >
>  > >  > >  > Hi,
>  > >  > >  > 
>  > >  > >  > I'm working on a GUI in which there is a 'GTree.list_store' of
>  > >  > >  > thumbnails (look at http://www.irisa.fr/lande/ferre/camelis
>  > >  > >  > for screen captions). I use the library CamlImages for
>  > >  > >  > computing these thumbnails from JPEG pictures.
>  > >  > > 
>  > >  > > Why don't you use GdkPixbuf for this ? It can load JPEG pictures. 
>  > >  > 
>  > >  > this is what I used at the beginning. But I noticed there was
>  > >  > something like a memory leak as the process rapidly grew to more
>  > >  > than 1Gb of memory, while I checked the loaded images were no more
>  > >  > reachable.
>  > > 
>  > > Ah. It might be a memory leak in lablgtk. I'd be interested if
>  > > you still have some code showing this problem.
>  > 
>  > If you call many times the function 'pixmap_of_picture', you should
>  > exhibit the problem. It seems the data in local variable 'pixbuf'
>  > is never deallocated (while the use of Gc.finalize shows it do
>  > become unreachable, as expected).
> 
> Argl. OK I remember: indeed GdkPixbuf.from_file had a leak in lablgtk
> 2.4.0 (the pixbuf was referenced before being returned to caml and
> thus never deallocated). I fixed this in the first snapshot after
> lablgtk 2.4.0 (2004-11-19). But later, when I added support for
> serialisation of GdkPixbufs, I inadvertently broke the reference
> counting. This means that with the latest snapshot all functions
> creating pixbufs (like GdkPixbuf.copy, new_from_file, etc.) leak the
> pixbuf. (This will be fixed in the next version of course).
> 
>  > >  > Also, CamlImages allows for loading directly a thumbnail from
>  > >  > JPEG pictures, which is lighter.
>  > > 
>  > > GdkPixbuf has a GdkPixbuf.from_file_at_size function that lets
>  > > you do that too (I hope so).
>  > 
>  > I can't find it. Is it in a newer version ? (I have version 2.4.0).
> 
> Yes it's in newer versions.
> 
> So, could you do this:
> 
>  - download the lastest lablgtk snapshot
>    http://wwwfun.kurims.kyoto-u.ac.jp/soft/olabl/dist/lablgtk2-20050701.tar.gz 
>  - apply the attached patch to fix the pixbuf refcounting
>  - compile, install
>  - test your program with GdkPixbuf.new_from_file/GdkPixbuf.scale : it
>    shouldn't leak anymore
>  - test your program with GdkPixbuf.new_from_file_at_size

Great! there is no more memory leak, in both cases.
And the solution with 'from_file_at_size' is much quicker.

There is only one last thing that is annoying, while not so
important. It is that even if a few pictures are displayed in
the list_store, it is not possible to select them while other
pictures are computed (with Glib.Idle) and displayed.
Do you have any hint on that subject ?

Thank you for your help !
Sebastien