Re: [gtk-list] Re: selecting an item in a tree widget (fwd)

[Alexandru Harsanyi <haral codec ro>]

Well, I tried to modify tree.c example from the gtk+ distribution. I added
my modified version to this mail. This particular example invokes
gtk_tree_select_item on the first item, after the first item and it's
subtree was created. It simply core dumps. (As I told you I tried
selecting the child at the end of the tree creation process too, but it
failed too).

On Thu, 15 Jul 1999, Michael Vance wrote:

> 
> > I'm trying to create a tree widget that has an item selected when the
> > window is popped up. I set up the tree widget (with all the subwidgets)
> > and than select the item I want. Unfortunately both gtk_tree_select_item
> > and gtk_tree_select_child cause a core dump when they are called.
> 
> Give us a code snippet. Does this happen when the signal is bound, caller, or
> inside the signal handler? If you get a namespace clash and do something like
> 
> gtk_signal_connect( GTK_OBJECT( write_button ), "clicked"
> 		    GTK_SIGNAL_FUNC( write ), NULL );

I don't know exactly what you mean, but my signal handler never gets
called (i put a breakpoint with gdb but it did not stop there). And I
suppose that the tree.c example is free of nameclases.

I also want to stress out that selecting items by clicking them with the
mouse works fine. Just selecting an item from inside the application does
not work.

> 
> this can cause a core dump.
> 
> m.
>   

Best regards,
alex.
/* example-start tree tree.c */

#include <gtk/gtk.h>

/* for all the GtkItem:: and GtkTreeItem:: signals */
static void cb_itemsignal (GtkWidget *item, gchar *signame)
{
  gchar *name;
  GtkLabel *label;

  /* It's a GtkBin, so it has one child, which we know to be a
     label, so get that */
  label = GTK_LABEL (GTK_BIN (item)->child);
  /* Get the text of the label */
  gtk_label_get (label, &name);
  /* Get the level of the tree which the item is in */
  g_print ("%s called for item %s->%p, level %d\n", signame, name,
	   item, GTK_TREE (item->parent)->level);
}

/* Note that this is never called */
static void cb_unselect_child (GtkWidget *root_tree, GtkWidget *child,
			       GtkWidget *subtree)
{
  g_print ("unselect_child called for root tree %p, subtree %p, child %p\n",
	   root_tree, subtree, child);
}

/* Note that this is called every time the user clicks on an item,
   whether it is already selected or not. */
static void cb_select_child (GtkWidget *root_tree, GtkWidget *child,
			     GtkWidget *subtree)
{
  g_print ("select_child called for root tree %p, subtree %p, child %p\n",
	   root_tree, subtree, child);
}

static void cb_selection_changed (GtkWidget *tree)
{
  GList *i;
  
  g_print ("selection_change called for tree %p\n", tree);
  g_print ("selected objects are:\n");

  i = GTK_TREE_SELECTION(tree);
  while (i){
    gchar *name;
    GtkLabel *label;
    GtkWidget *item;

    /* Get a GtkWidget pointer from the list node */
    item = GTK_WIDGET (i->data);
    label = GTK_LABEL (GTK_BIN (item)->child);
    gtk_label_get (label, &name);
    g_print ("\t%s on level %d\n", name, GTK_TREE
	     (item->parent)->level);
    i = i->next;
  }
}

int main (int argc, char *argv[])
{
  GtkWidget *window, *scrolled_win, *tree;
  static gchar *itemnames[] = {"Foo", "Bar", "Baz", "Quux",
                               "Maurice"};
  gint i;

  gtk_init (&argc, &argv);

  /* a generic toplevel window */
  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_signal_connect (GTK_OBJECT(window), "delete_event",
		      GTK_SIGNAL_FUNC (gtk_main_quit), NULL);
  gtk_container_set_border_width (GTK_CONTAINER(window), 5);

  /* A generic scrolled window */
  scrolled_win = gtk_scrolled_window_new (NULL, NULL);
  gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_win),
				  GTK_POLICY_AUTOMATIC,
				  GTK_POLICY_AUTOMATIC);
  gtk_widget_set_usize (scrolled_win, 150, 200);
  gtk_container_add (GTK_CONTAINER(window), scrolled_win);
  gtk_widget_show (scrolled_win);
  
  /* Create the root tree */
  tree = gtk_tree_new();
  g_print ("root tree is %p\n", tree);
  /* connect all GtkTree:: signals */
  gtk_signal_connect (GTK_OBJECT(tree), "select_child",
		      GTK_SIGNAL_FUNC(cb_select_child), tree);
  gtk_signal_connect (GTK_OBJECT(tree), "unselect_child",
		      GTK_SIGNAL_FUNC(cb_unselect_child), tree);
  gtk_signal_connect (GTK_OBJECT(tree), "selection_changed",
		      GTK_SIGNAL_FUNC(cb_selection_changed), tree);
  /* Add it to the scrolled window */
  gtk_scrolled_window_add_with_viewport (GTK_SCROLLED_WINDOW(scrolled_win),
                                         tree);
  /* Set the selection mode */
  gtk_tree_set_selection_mode (GTK_TREE(tree),
			       GTK_SELECTION_SINGLE);
  /* Show it */
  gtk_widget_show (tree);

  for (i = 0; i < 5; i++){
    GtkWidget *subtree, *item;
    gint j;

    /* Create a tree item */
    item = gtk_tree_item_new_with_label (itemnames[i]);
    /* Connect all GtkItem:: and GtkTreeItem:: signals */
    gtk_signal_connect (GTK_OBJECT(item), "select",
			GTK_SIGNAL_FUNC(cb_itemsignal), "select");
    gtk_signal_connect (GTK_OBJECT(item), "deselect",
			GTK_SIGNAL_FUNC(cb_itemsignal), "deselect");
    gtk_signal_connect (GTK_OBJECT(item), "toggle",
			GTK_SIGNAL_FUNC(cb_itemsignal), "toggle");
    gtk_signal_connect (GTK_OBJECT(item), "expand",
			GTK_SIGNAL_FUNC(cb_itemsignal), "expand");
    gtk_signal_connect (GTK_OBJECT(item), "collapse",
			GTK_SIGNAL_FUNC(cb_itemsignal), "collapse");
    /* Add it to the parent tree */
    gtk_tree_append (GTK_TREE(tree), item);

    /* Show it - this can be done at any time */
    gtk_widget_show (item);
    /* Create this item's subtree */
    subtree = gtk_tree_new();
    g_print ("-> item %s->%p, subtree %p\n", itemnames[i], item,
	     subtree);

    /* This is still necessary if you want these signals to be called
       for the subtree's children.  Note that selection_change will be 
       signalled for the root tree regardless. */
    gtk_signal_connect (GTK_OBJECT(subtree), "select_child",
			GTK_SIGNAL_FUNC(cb_select_child), subtree);
    gtk_signal_connect (GTK_OBJECT(subtree), "unselect_child",
			GTK_SIGNAL_FUNC(cb_unselect_child), subtree);
    /* This has absolutely no effect, because it is completely ignored 
       in subtrees */
    gtk_tree_set_selection_mode (GTK_TREE(subtree),
				 GTK_SELECTION_SINGLE);
    /* Neither does this, but for a rather different reason - the
       view_mode and view_line values of a tree are propagated to
       subtrees when they are mapped.  So, setting it later on would
       actually have a (somewhat unpredictable) effect */
    gtk_tree_set_view_mode (GTK_TREE(subtree), GTK_TREE_VIEW_ITEM);
    /* Set this item's subtree - note that you cannot do this until
       AFTER the item has been added to its parent tree! */
    gtk_tree_item_set_subtree (GTK_TREE_ITEM(item), subtree);

    for (j = 0; j < 5; j++){
      GtkWidget *subitem;

      /* Create a subtree item, in much the same way */
      subitem = gtk_tree_item_new_with_label (itemnames[j]);
      /* Connect all GtkItem:: and GtkTreeItem:: signals */
      gtk_signal_connect (GTK_OBJECT(subitem), "select",
			  GTK_SIGNAL_FUNC(cb_itemsignal), "select");
      gtk_signal_connect (GTK_OBJECT(subitem), "deselect",
			  GTK_SIGNAL_FUNC(cb_itemsignal), "deselect");
      gtk_signal_connect (GTK_OBJECT(subitem), "toggle",
			  GTK_SIGNAL_FUNC(cb_itemsignal), "toggle");
      gtk_signal_connect (GTK_OBJECT(subitem), "expand",
			  GTK_SIGNAL_FUNC(cb_itemsignal), "expand");
      gtk_signal_connect (GTK_OBJECT(subitem), "collapse",
			  GTK_SIGNAL_FUNC(cb_itemsignal), "collapse");
      g_print ("-> -> item %s->%p\n", itemnames[j], subitem);
      /* Add it to its parent tree */
      gtk_tree_append (GTK_TREE(subtree), subitem);
      /* Show it */
      gtk_widget_show (subitem);
    }
    /* haral */
    if(i==0)
      gtk_tree_select_item(GTK_TREE(tree), 0); /* select first item */
    /* haral */
  }

  /* Show the window and loop endlessly */
  gtk_widget_show (window);
  gtk_main();
  return 0;
}
/* example-end */