[gcompris-devel] 2 programming questions

[Bruno Coudoin]

le jeu 15-11-2001 à 20:26, pgeorges a écrit :
> I have 2 problems and would like to know if somebody can help :
> 
> 1. How to move an item at an absolute position (not a relative one). I
> am using a work around with a mix of 
> 
> 	gnome_canvas_item_get_bounds(item, &dx1, &dy1, &dx2, &dy2);
> 	gnome_canvas_item_move(item, xOffset-dx1, line[0]-dy2);
> 
I did not find either. The shape board is full of what your doing :(

> (don't stare at parameters). This works but I would like something less
> ugly.
> 
> 2. More important (here i am stuck) : I don't know how to clear a GList.
> 
> If I use 
> g_list_free(int_model_list);
> 
I think that when you free it, then you keep the pointer to a freed
memory. It is different concept than clearing or emptying it.

Look at my code, I m using it with some success ;)

> the length of the list is not 0 !!
> 
> worse if I use my helper function below, the length of the list is not
> 0, but remains the same as it was before !
> 
> /* ==================================== */
> static void reset_list(GList * list) {
>   int i;
>   for (i=0; i<g_list_length(list); i++)
> 	list = g_list_remove(list, g_list_nth_data(list,0));
> }
> 
First a remark, you do a for loop but do not use 'i'. It probably means
that the 'for' is not the correct answer here.
In fact, i is being increased and g_list_length(list) decreases so you
will never complete the clenup. It you have 10 elements, when i is 5,
the remaining list nth is 5 and you end the loop :(

This code works: 

static void algebra_destroy_item(GnomeCanvasItem *item)
{
  item_list = g_list_remove (item_list, item);
  gtk_object_destroy (GTK_OBJECT(item));
}


 while(g_list_length(item_list)>0) 
    {
      item = g_list_nth_data(item_list, 0);
      algebra_destroy_item(item);
    }

> 
> I checked the news, but It seems that I am alone not to be able to cope
> with this.
> 
> Pascal
> 
> 
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-- 
Bruno Coudoin
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