Re: Pixmap theme, caching and gnome-pixmaps

[James Henstridge <james daa com au>]

I think there is another way to fix this problem which doesn't involve the
pixmap copying overhead.  Basically free_pixmap_and_mask in gnome-pixmap.c
is wrong.

According to the imlib documentation, to free a pixmap that has been
created by imlib, you call the following function:
  void gdk_imlib_free_pixmap(GdkPixmap *pixmap);
This function will also free the associated mask, and take the imlib cache
into account.

In free_pixmap_and_mask, it uses gdk_pixmap_unref directly, which is what
is stuffing up imlib's internal structures.  The correct implementation of
free_pixmap_and_mask should be:

static void
free_pixmap_and_mask (GnomePixmap *gpixmap)
{
        g_return_if_fail (gpixmap != NULL);
        g_return_if_fail (GNOME_IS_PIXMAP (gpixmap));

        if (gpixmap->pixmap) {
                gdk_imlib_free_pixmap (gpixmap->pixmap);
                gpixmap->pixmap = NULL;
                gpixmap->mask = NULL;
        }
}

I have not tested this, but if it doesn't work correctly, then it would be
an imlib problem.

James Henstridge.

--
Email: james@daa.com.au
WWW:   http://www.daa.com.au/~james/


On 29 Mar 1999, Owen Taylor wrote:

> 
> The problems people have been having with *Bad Window*
> errors and pixmap themes seem to be occurring because
> of mistakes in the way that gnome-pixmap is handling
> Imlib images. (Well, actually, they are occurring because
> of mistakes in the design of imlib...)
> 
> To be specific, gnome-pixmap widget calls 
> gdk_imlib_move_pixmap() and gdk_imlib_move_mask(), then
> gdk_imlib_destroy_image(). 
> 
> If no caching is enabled, then this works pretty
> much as expected - the pixmaps and masks are dissociated
> from the image and the imlib data structures are cleaned
> up.
> 
> If caching is enabled, then bad things happen. move_pixmap()
> and move_mask() leave the pixmaps in the cache; the
> destroy_image() drops the refcount of the pixmaps to 
> zero, and when the cache gets full, the pixmaps are
> destroyed.
> 
> The following patch fixes things up, but is a rather
> inefficient, since it puts every pixmap in GNOME through
> a extra copy. I'm not really sure how to do this
> better - I'll ask Raster about it when he gets back
> from Germany. 
>                                         Owen
> 
> Index: gnome-pixmap.c
> ===================================================================
> RCS file: /cvs/gnome/gnome-libs/libgnomeui/gnome-pixmap.c,v
> retrieving revision 1.32
> diff -u -r1.32 gnome-pixmap.c
> --- gnome-pixmap.c	1999/03/21 09:02:20	1.32
> +++ gnome-pixmap.c	1999/03/29 20:23:06
> @@ -617,8 +617,8 @@
>  	else
>  		gdk_imlib_render (im, im->rgb_width, im->rgb_height);
>  
> -	gpixmap->pixmap = gdk_imlib_move_image (im);
> -	gpixmap->mask = gdk_imlib_move_mask (im);
> +	gpixmap->pixmap = gdk_imlib_copy_image (im);
> +	gpixmap->mask = gdk_imlib_copy_mask (im);
>  
>  	if (destroy)
>  		gdk_imlib_destroy_image (im);
> 
> 
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