Re: [gtk-list] Runtime Linkage queries

[Tim Janik <timj gtk org>]

Grrr, of course i posted the wrong prototypes,
here they go corrected:

On Fri, 12 Jun 1998, Tim Janik wrote:

> hi everyone,
> 
> user interface builders usually let you create complete guis through
> creating and placing widgets/containers in other containers.
> gtk implements a mechanism to query/set widget specific arguments to
> control widget specific behaviour, but does not (yet) support a way
> for runtime settings/adjustments of the way a container links in a
> child.
> i therefore would like the following things to be implemented:
> 
> - a way to query a container about the expected type of child
> - a way to query the supported linkage arguments of a container
> - a way to set these linkage arguments.
> 
> for the implementation side i'd like to see...
> 
> the GtkContainerClass extended to support the following methods:
> 
> struct _GtkContainerClass
> {
>   [...]
>   
>   void    (*get_linkage_arg)  (GtkContainer *container,
>   			       GtkWidget    *child,
>                                GtkArg       *arg,
>                                guint         arg_id);
>   void    (*set_linkage_arg)  (GtkContainer *container,
>   			       GtkWidget    *child,
>                                GtkArg       *arg,
>                                guint         arg_id);
>   
>   GtkType (*next_child_slot)  (GtkContainer *container);
> };
> 
> the following functions to be implemented on gtkcontainer basis:
> 
> GtkType gtk_container_next_child_slot (GtkContainer *container);
> 
> /* this function is similar to gtk_object_add_arg_type */
void    gtk_container_add_linkage_arg_type (const gchar       *arg_name,
                                            GtkType            arg_type,
                                            guint              arg_flags,
                                            guint              arg_id);
> 
> /* this function is similar to gtk_object_query_args */
GtkArg* gtk_container_query_linkage_args (GtkType            class_type,
                                          guint32          **arg_flags,
                                          guint             *nargs);
> 
> /* the following functions are in place to set/get the linkage
>  * arguments through the newly introduced class methods
>  */
> 
> /* this function is similar to gtk_object_getv */
> void    gtk_container_linkage_getv    (GtkContainer *container,
> 				       GtkWidget    *child,
>                                        guint         n_args,
> 				       GtkArg       *args);
> 
> /* this function is similar to gtk_object_setv */
> void    gtk_container_linkage_setv    (GtkContainer *container,
> 				       GtkWidget    *child,
>                                        guint         n_args,
> 				       GtkArg       *args);
> 
> 
> /* this function is a combination of gtk_container_add and
>  * gtk_container_linkage_setv, similar to the semantics of
>  * gtk_object_new
>  */
> void    gtk_container_linkage_add     (GtkContainer *container,
> 				       GtkWidget    *child,
> 				       ...);
> 
> /* this function is a combination of gtk_container_add and
>  * gtk_container_linkage_setv, similar to the semantics of
>  * gtk_object_newv
>  */
> void    gtk_container_linkage_addv    (GtkContainer *container,
> 				       GtkWidget    *child,
>                                        guint         n_args,
> 				       GtkArg       *args);
> 
> 
> the gtk_container_next_child_slot() will return the expected base type
> of new children.
> examples:
> a GtkWindow would return GTK_TYPE_WIDGET if it doesn't yet have a child,
> and GTK_TYPE_NONE otherwise (since it is derived from GtkBin it can hold
> one child at maximum).
> a GtkBox would always return GTK_TYPE_WIDGET, since it can hold an unlimited
> amount of children.
> a GtkList would always return GTK_TYPE_LIST_ITEM, since that is the minimum
> base class a list's children have to be derived from, and a GtkList can hold
> an unlimited amount of children as well.
> a GtkPaned would return GTK_TYPE_WIDGET as long as one of its two child slots
> is unallocated.
> 
> basically, the linkage argument functions operate similar to the object
> argument mechanism, they just have an extra child widget specified.
> e.g. a GtkBox will introduce the following linkage arguments:
> 
> GtkBox::expand  bool
> GtkBox::fill    bool
> GtkBox::padding int
> 
> the usage of linkage arguments is actually straight forward, once one
> got familiar with the object argument mechanism. a small example prog:
> 
> GtkWidget *box;
> GtkWidget *label;
> GtkWidget *window;
> 
> gtk_init (NULL, NULL);
> 
> window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
> 
> box = gtk_widget_new (GTK_TYPE_BOX,
>                       "GtkBox::homogenous", TRUE,
>                       "GtkWidget::visible", TRUE,
>                       "GtkWidget::parent", window,
> 		      NULL);
> label = gtk_widget_new (GTK_TYPE_LABEL,
> 			"GtkWidget::visible", TRUE,
> 			"GtkLabel::label", "yeppers",
> 			NULL);
> gtk_container_linkage_add (box,
>                            label,
>                            "GtkBox::expand", TRUE,
>                            "GtkBox::fill", TRUE,
>                            "GtkBox::padding", 4,
>                            NULL);
> gtk_widget_show (window);
> gtk_main ();
> 
> 
> i'm curious about people's comments, especially damon's ;)
> 
> ---
> ciaoTJ
> 

---
ciaoTJ