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<chapter id="gtk-migrating-GtkComboBox">
<title>Migrating from GtkOptionMenu and GtkCombo to GtkComboBox and
GtkComboBoxEntry</title>
<para>
Prior to 2.4, GTK+ offered two widgets for the task of selecting one
item from a list of options. #GtkOptionMenu presents the list of
options as a menu while #GtkCombo presents them in a Windows-style list
popup. The only difference between the two is that a #GtkCombo allows to
manually edit the selected value, while the #GtkOptionMenu does not.
</para>
<para>
In GTK+ 2.4, a unified API for list selection was introduced, with
#GtkComboBox for the non-editable case and #GtkComboBoxEntry for the
editable case.
The selection of the display style — menu or list —
is no longer done at the API level, but has been made themeable via
the style property #GtkComboBox:appears-as-list.
</para>
<section id="migrating-GtkOptionMenu">
<title>Migrating from GtkOptionMenu to GtkComboBox</title>
<para>
Here is an example of a simple, but typical use of
#GtkOptionMenu<!---->:
<informalexample><programlisting>
GtkWidget *option_menu, *menu, *menu_item;
option_menu = gtk_option_menu_new (<!-- -->);
menu = gtk_menu_new (<!-- -->);
menu_item = gtk_menu_item_new_with_label ("First Item");
gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
gtk_widget_show (menu_item);
menu_item = gtk_menu_item_new_with_label ("Second Item");
gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
gtk_widget_show (menu_item);
menu_item = gtk_menu_item_new_with_label ("Third Item");
gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
gtk_widget_show (menu_item);
gtk_option_menu_set_menu (GTK_OPTION_MENU (option_menu), menu);
</programlisting></informalexample>
In order to react to the user's selection, connect to the #GtkOptionMenu::changed
signal on the option menu and use gtk_option_menu_get_history()
to retrieve the index of the selected item.
</para>
<para>
And here is how it would be done with a #GtkComboBox<!---->:
<informalexample><programlisting>
GtkWidget *combo_box;
combo_box = gtk_combo_box_text_new (<!-- -->);
gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo_box), "First Item");
gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo_box), "Second Item");
gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo_box), "Third Item");
</programlisting></informalexample>
In order to react to the user's selection, connect to the
#GtkComboBox::changed signal and use gtk_combo_box_get_active()
to retrieve the index of the selected item.
</para>
<para>
A slightly more complex example involving images:
<informalexample><programlisting>
GtkWidget *option_menu, *menu, *menu_item;
option_menu = gtk_option_menu_new (<!-- -->);
menu = gtk_menu_new (<!-- -->);
menu_item = gtk_image_menu_item_new_with_label ("First Item");
gtk_image_menu_item_set_image (gtk_image_new_from_pixbuf (pixbuf1));
gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
gtk_widget_show (menu_item);
menu_item = gtk_image_menu_item_new_with_label ("Second Item");
gtk_image_menu_item_set_image (gtk_image_new_from_pixbuf (pixbuf2));
gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
gtk_widget_show (menu_item);
menu_item = gtk_image_menu_item_new_with_label ("Third Item");
gtk_image_menu_item_set_image (gtk_image_new_from_pixbuf (pixbuf3));
gtk_menu_shell_append (GTK_MENU_SHELL (menu), menu_item);
gtk_widget_show (menu_item);
gtk_option_menu_set_menu (GTK_OPTION_MENU (option_menu), menu);
</programlisting></informalexample>
</para>
<para>
can be done using a #GtkComboBox as follows:
<informalexample><programlisting>
GtkListStore *store;
GtkTreeIter iter;
GtkCellRenderer *renderer;
GtkWidget *combo_box;
store = gtk_list_store_new (2, GDK_TYPE_PIXBUF, G_TYPE_STRING);
gtk_list_store_append (store, &iter);
gtk_list_store_set (store, &iter, 0, pixbuf1, 1, "First Item", -1);
gtk_list_store_append (store, &iter);
gtk_list_store_set (store, &iter, 0, pixbuf2, 1, "Second Item", -1);
gtk_list_store_append (store, &iter);
gtk_list_store_set (store, &iter, 0, pixbuf3, 1, "Third Item", -1);
combo_box = gtk_combo_box_new_with_model (GTK_TREE_MODEL (store));
renderer = gtk_cell_renderer_pixbuf_new (<!-- -->);
gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (combo_box), renderer, FALSE);
gtk_cell_layout_set_attributes (GTK_CELL_LAYOUT (combo_box), renderer,
"pixbuf", 0,
NULL);
renderer = gtk_cell_renderer_text_new (<!-- -->);
gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (combo_box), renderer, TRUE);
gtk_cell_layout_set_attributes (GTK_CELL_LAYOUT (combo_box), renderer,
"text", 1,
NULL);
</programlisting></informalexample>
</para>
</section>
<section id="migrating-GtkCombo">
<title>Migrating from GtkCombo to GtkComboBoxEntry</title>
<para>
Here is an example of a simple, but typical use of a #GtkCombo<!---->:
<informalexample><programlisting>
GtkWidget *combo;
GList *items = NULL;
items = g_list_append (items, "First Item");
items = g_list_append (items, "Second Item");
items = g_list_append (items, "Third Item");
combo = gtk_combo_new (<!-- -->);
gtk_combo_set_popdown_strings (GTK_COMBO (combo), items);
</programlisting></informalexample>
In order to react to the user's selection, connect to the #GtkCombo::changed
signal on the combo and use
<literal>gtk_entry_get_text (GTK_ENTRY (combo->entry))</literal>
to retrieve the selected text.
</para>
<para>
And here is how it would be done using #GtkComboBoxEntry<!---->:
<informalexample><programlisting>
combo_box = gtk_combo_box_text_new_with_entry (<!-- -->);
gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo_box), "First Item");
gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo_box), "Second Item");
gtk_combo_box_text_append (GTK_COMBO_BOX_TEXT (combo_box), "Third Item");
</programlisting></informalexample>
In order to react to the user's selection, connect to the #GtkComboBox::changed
signal on the combo and use
<literal>gtk_entry_get_text (GTK_ENTRY (GTK_BIN (combo_box)->child))</literal>
to retrieve the selected text.
</para>
</section>
<section id="new-features-GtkComboBox">
<title>New features</title>
<para>
The new widgets have more to offer than a mere combination of the
features of #GtkOptionMenu and #GtkCombo. Notable new features
include:
<variablelist>
<varlistentry>
<term>Grid mode</term>
<listitem><para>Sometimes it is preferable to display the available
options not in a linear list, but in a grid. A typical example
would be a "color combo" where the individual items are small
square color swatches. The new widgets support gridded display
with the functions
gtk_combo_box_set_wrap_width(),
gtk_combo_box_set_row_span_column() and
gtk_combo_box_set_column_span_column().
</para></listitem>
</varlistentry>
<varlistentry>
<term>Display of icons</term>
<listitem><para>An often-heard complaint about #GtkOptionMenu is that
the icons which appear in the image menu items in its menu are not
displayed in the button showing the selected item. This limitation
has been removed in #GtkComboBox; the selected item appears in the
same way as the options in the popup.
</para></listitem>
</varlistentry>
<varlistentry>
<term>Full tree model power</term>
<listitem><para>
Since the new widgets are built around the same models that are
used for #GtkTreeView, all of the powerful machinery of tree models
and cell renderers can be used.
</para></listitem>
</varlistentry>
</variablelist>
</para>
</section>
</chapter>
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