GtkListStore
A list-like data structure that can be used with the GtkTreeView
The #GtkListStore object is a list model for use with a #GtkTreeView
widget. It implements the #GtkTreeModel interface, and consequentialy,
can use all of the methods available there. It also implements the
#GtkTreeSortable interface so it can be sorted by the view.
Finally, it also implements the tree drag and
drop interfaces.
The #GtkListStore can accept most GObject types as a column type, though
it can't accept all custom types. Internally, it will keep a copy of
data passed in (such as a string or a boxed pointer). Columns that
accept #GObjects are handled a little differently. The
#GtkListStore will keep a reference to the object instead of copying the
value. As a result, if the object is modified, it is up to the
application writer to call @gtk_tree_model_row_changed to emit the
"row_changed" signal. This most commonly affects lists with
#GdkPixbufs stored.
Creating a simple list store.
enum {
COLUMN_STRING,
COLUMN_INT,
COLUMN_BOOLEAN,
N_COLUMNS
};
{
GtkListStore *list_store;
GtkTreePath *path;
GtkTreeIter iter;
gint i;
list_store = gtk_list_store_new (N_COLUMNS,
G_TYPE_STRING,
G_TYPE_INT,
G_TYPE_BOOLEAN);
for (i = 0; i < 10; i++)
{
gchar *some_data;
some_data = get_some_data (i);
/* Add a new row to the model */
gtk_list_store_append (list_store, &iter);
gtk_list_store_set (list_store, &iter,
COLUMN_STRING, some_data,
COLUMN_INT, i,
COLUMN_BOOLEAN, FALSE,
-1);
/* As the store will keep a copy of the string internally, we
* free some_data.
*/
g_free (some_data);
}
/* Modify a particular row */
path = gtk_tree_path_new_from_string ("4");
gtk_tree_model_get_iter (GTK_TREE_MODEL (list_store),
&iter,
path);
gtk_tree_path_free (path);
gtk_list_store_set (list_store, &iter,
COLUMN_BOOLEAN, TRUE,
-1);
}
Performance Considerations
Internally, the #GtkListStore was implemented with a linked list with a
tail pointer prior to GTK+ 2.6. As a result, it was fast at data
insertion and deletion, and not fast at random data access. The
#GtkListStore sets the #GTK_TREE_MODEL_ITERS_PERSIST flag, which means
that #GtkTreeIters can be cached while the row exists. Thus, if
access to a particular row is needed often and your code is expected to
run on older versions of GTK+, it is worth keeping the iter around.
Atomic Operations
It is important to note that only the methods
gtk_list_store_insert_with_values() and gtk_list_store_insert_with_valuesv()
are atomic, in the sense that the row is being appended to the store and the
values filled in in a single operation with regard to #GtkTreeModel signaling.
In contrast, using e.g. gtk_list_store_append() and then gtk_list_store_set()
will first create a row, which triggers the #GtkTreeModel::row-inserted signal
on #GtkListStore. The row, however, is still empty, and any signal handler
connecting to "row-inserted" on this particular store should be prepared
for the situation that the row might be empty. This is especially important
if you are wrapping the #GtkListStore inside a #GtkTreeModelFilter and are
using a #GtkTreeModelFilterVisibleFunc. Using any of the non-atomic operations
to append rows to the #GtkListStore will cause the
#GtkTreeModelFilterVisibleFunc to be visited with an empty row first; the
function must be prepared for that.
GtkListStore as GtkBuildable
The GtkListStore implementation of the GtkBuildable interface allows
to specify the model columns with a <columns> element that may
contain multiple <column> elements, each specifying one model
column. The "type" attribute specifies the data type for the column.
Additionally, it is possible to specify content for the list store
in the UI definition, with the <data> element. It can contain
multiple <row> elements, each specifying to content for one
row of the list model. Inside a <row>, the <col> elements
specify the content for individual cells.
Note that it is probably more common to define your models
in the code, and one might consider it a layering violation
to specify the content of a list store in a UI definition,
data, not presentation,
and common wisdom is to separate the two, as far as possible.
A UI Definition fragment for a list store