Re: GtkLayout, segfaulting with [hv]adjustment properties

[Owen Taylor <otaylor redhat com>]

jacob berkman <jacob ximian com> writes:

> i am getting a segfault in GtkLayout if i set the height/width
> properties before [hv]adjustment properties.
> 
> in looking at it, i think it makes sense in gtk_layout_init() to call
> gtk_layout_set_adjustments(layout, NULL, NULL) rather than setting both
> of the adjustments to NULL.
> 
> this is because typically, you are calling gtk_layout_new(), which does
> call gtk_layout_set_adjustments().
> 
> i've attached some sample code wich seg faults with current cvs, but
> doesn't with the attached patch.

Hmm, I think it was already bad that 

 layout = gtk_layout_new (NULL, NULL);
 gtk_container_add (scrolled_window, layout);

Generated and destroyed one set of adjustments. With your change,
it generates and destroys _two_ sets, which, I think, is just
too ugly to be acceptable.

One sketch of a solution would be to:

 * If NULL adjustments are set during construction, don't create
   adjustments

 * Create default adjustments in a constructor() methods if
   hadjustment, vadjustment are NULL.

 * Make sure that all properties can be set prior to creating
   the adjustments.

Regards,
                                        Owen

> Index: gtklayout.c
> ===================================================================
> RCS file: /cvs/gnome/gtk+/gtk/gtklayout.c,v
> retrieving revision 1.44
> diff -u -r1.44 gtklayout.c
> --- gtklayout.c	2001/09/08 19:33:05	1.44
> +++ gtklayout.c	2001/11/14 18:12:37
> @@ -774,6 +774,8 @@
>    layout->visibility = GDK_VISIBILITY_PARTIAL;
>  
>    layout->freeze_count = 0;
> +
> +  gtk_layout_set_adjustments (layout, NULL, NULL);
>  }
>  
>  /* Widget methods
> 
> #include <gtk/gtk.h>
> 
> int
> main (int argc, char *argv[])
> {
>   GtkAdjustment *h, *v;
>   GtkWidget *layout;
> 
>   gtk_init (&argc, &argv);
> 
>   h = gtk_adjustment_new (0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
>   v = gtk_adjustment_new (0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
> 
>   g_object_new (GTK_TYPE_LAYOUT, 
> 		"height", 100,
> 		"width", 100,
> 		"hadjustment", h,
> 		"vadjustment", v,
> 		NULL);
> }