Re: TreeView/ListStore reordering by DND

[Nicola Fontana <ntd entidi it>]

Il Sat, 01 Mar 2014 19:35:08 +0100 Stefan Salewski <mail ssalewski de> scrisse:

> On Sat, 2014-03-01 at 02:08 +0100, Stefan Salewski wrote:
> [...]
> Here is my complete C code:
>
> http://www.ssalewski.de/tmp/test.c
>
> I inserted these lines:
>
> void on_row_inserted(GtkTreeModel *tree_model, GtkTreePath *path,
> GtkTreeIter *iter, gpointer user_data)
> {
>   char *value;
>   printf("row_inserted\n");
>   gtk_tree_model_get(tree_model, iter, LIST_ITEM, &value, -1);
>   g_printf("value = %s\n", value);
>   gint *i = gtk_tree_path_get_indices(path);
>   g_printf("row ins = %d\n", i[0]);
> }
>
> void on_row_deleted(GtkTreeModel *tree_model, GtkTreePath *path, gpointer user_data)
> {
>   printf("row_deleted\n");
>   gint *i = gtk_tree_path_get_indices(path);
>   g_printf("row del = %d\n", i[0]);
> }
>
> First question:
> When I exchange rows by drag and drop, I get
>
> value = (null)
>
> similar to my test from Ruby yesterday. Is this intended, or is my code
> wrong (I have not much practice with using GTK from plain C...)

Hi,

this is intended behavior. The problem is the insertion is done in two
steps: (1) an empty row is created (and your on_row_inserted() callback
is called) and (2) that row is filled with data.

If you want 'value' to be meaningful you must postpone your callback, e.g.
by using g_idle_add(). Try to substitute your on_row_inserted() with the
following code:


typedef struct {
    GtkTreeModel *model;
    GtkTreePath *path;
} CallbackData;

static gboolean
real_row_inserted(CallbackData *data)
{
    GtkTreeIter iter;

    if (gtk_tree_model_get_iter(data->model, &iter, data->path)) {
        gchar *value;
        gtk_tree_model_get(data->model, &iter, LIST_ITEM, &value, -1);
        g_print("Row inserted: value = '%s'\n", value);
        g_free(value);
    }

    gtk_tree_path_free(data->path);
    g_free(data);
    return FALSE;
}

static void
on_row_inserted(GtkTreeModel *tree_model, GtkTreePath *path,
        GtkTreeIter *iter, gpointer user_data)
{
    CallbackData *data = g_new(CallbackData, 1);
    data->model = tree_model;
    data->path = gtk_tree_path_copy(path);
    g_idle_add((GSourceFunc) real_row_inserted, data);
}


Ciao.
-- 
Nicola