demo: Add a listview sections demo

Just display the list of objects from GTK, and order them in some
made-up categories.

demos/gtk-demo/demo.gresource.xml

@@ -305,6 +305,7 @@
     <file>listview_clocks.c</file>
     <file>listview_filebrowser.c</file>
     <file>listview_minesweeper.c</file>
+    <file>listview_objects.c</file>
     <file>listview_settings.c</file>
     <file>listview_ucd.c</file>
     <file>listview_weather.c</file>

demos/gtk-demo/listview_objects.c

@@ -0,0 +1,220 @@
+/* Lists/Objects in GTK
+ * #Keywords: GtkListItemFactory, GtkSortListModel, GtkStringList
+ *
+ * This demo uses the GtkListView widget to show all the objects in GTK
+ * grouped by their type.
+ *
+ * It shows how to use sections in GtkListView
+ */
+
+#include <gtk/gtk.h>
+
+/* This is the function that creates the GListModel that we need.
+ */
+static GListModel *
+create_object_list (void)
+{
+  GtkStringList *strings;
+  const GType *types;
+  guint i, n;
+
+  /* We use a GtkStringList here, because it requires the smallest amount of
+   * code, not because it's a great fit.
+   */
+  strings = gtk_string_list_new (NULL);
+
+  /* This function is meant for testing, but we use it here to get some data
+   * to operate on
+   */
+  gtk_test_register_all_types ();
+  types = gtk_test_list_all_types (&n);
+
+  for (i = 0; i < n; i++)
+    {
+      /* Add all the names of the object types in GTK */
+      if (g_type_is_a (types[i], G_TYPE_OBJECT))
+        gtk_string_list_append (strings, g_type_name (types[i]));
+    }
+
+  return G_LIST_MODEL (strings);
+}
+
+/* Make a function that returns a section name for all our types.
+ * Do this by adding a few type checks and returning a made up
+ * section name for it.
+ */
+static char *
+get_section (GtkStringObject *object)
+{
+  GType type;
+
+  type = g_type_from_name (gtk_string_object_get_string (object));
+
+  if (g_type_is_a (type, GTK_TYPE_WIDGET))
+    return g_strdup ("Widget");
+  else if (g_type_is_a (type, GTK_TYPE_FILTER))
+    return g_strdup ("Filter");
+  else if (g_type_is_a (type, GTK_TYPE_SORTER))
+    return g_strdup ("Sorter");
+  else if (g_type_is_a (type, G_TYPE_LIST_MODEL))
+    return g_strdup ("ListModel");
+  else
+    return g_strdup ("Zzz..."); /* boring stuff, cleverly sorted at the end */
+}
+
+/* These functions set up the object names
+ */
+static void
+setup_section_listitem_cb (GtkListItemFactory *factory,
+                           GtkListItem        *list_item)
+{
+  GtkWidget *label;
+
+  label = gtk_label_new ("");
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_widget_add_css_class (label, "heading");
+  gtk_widget_set_margin_top (label, 4);
+  gtk_widget_set_margin_bottom (label, 4);
+  gtk_list_item_set_child (list_item, label);
+}
+
+/* Here we need to prepare the listitem for displaying its item. We get the
+ * listitem already set up from the previous function, so we can reuse the
+ * GtkImage widget we set up above.
+ * We get the item - which we know is a GAppInfo because it comes out of
+ * the model we set up above, grab its icon and display it.
+ */
+static void
+bind_section_listitem_cb (GtkListItemFactory *factory,
+                          GtkListItem        *list_item)
+{
+  GtkWidget *label;
+  GtkStringObject *item;
+  char *text;
+
+  label = gtk_list_item_get_child (list_item);
+  item = gtk_list_item_get_item (list_item);
+
+  text = get_section (item);
+  gtk_label_set_label (GTK_LABEL (label), text);
+  g_free (text);
+}
+
+static void
+setup_listitem_cb (GtkListItemFactory *factory,
+                   GtkListItem        *list_item)
+{
+  GtkWidget *label;
+
+  label = gtk_label_new ("");
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_list_item_set_child (list_item, label);
+}
+
+/* Here we need to prepare the listitem for displaying its item. We get the
+ * listitem already set up from the previous function, so we can reuse the
+ * GtkImage widget we set up above.
+ * We get the item - which we know is a GAppInfo because it comes out of
+ * the model we set up above, grab its icon and display it.
+ */
+static void
+bind_listitem_cb (GtkListItemFactory *factory,
+                  GtkListItem        *list_item)
+{
+  GtkWidget *label;
+  GtkStringObject *item;
+
+  label = gtk_list_item_get_child (list_item);
+  item = gtk_list_item_get_item (list_item);
+
+  gtk_label_set_label (GTK_LABEL (label), gtk_string_object_get_string (item));
+}
+
+/* In more complex code, we would also need functions to unbind and teardown
+ * the listitem, but this is simple code, so the default implementations are
+ * enough. If we had connected signals, this step would have been necessary.
+ *
+ * The GtkSignalListItemFactory documentation contains more information about
+ * this step.
+ */
+
+static GtkWidget *window = NULL;
+
+GtkWidget *
+do_listview_objects (GtkWidget *do_widget)
+{
+  if (window == NULL)
+    {
+      GtkWidget *list, *sw;
+      GListModel *model;
+      GtkListItemFactory *factory;
+      GtkSorter *sorter;
+
+      /* Create a window and set a few defaults */
+      window = gtk_window_new ();
+      gtk_window_set_default_size (GTK_WINDOW (window), 300, 400);
+      gtk_window_set_display (GTK_WINDOW (window),
+                              gtk_widget_get_display (do_widget));
+      gtk_window_set_title (GTK_WINDOW (window), "Objects in GTK");
+      g_object_add_weak_pointer (G_OBJECT (window), (gpointer *) &window);
+
+      /* The GtkListitemFactory is what is used to create GtkListItems
+       * to display the data from the model. So it is absolutely necessary
+       * to create one.
+       * We will use a GtkSignalListItemFactory because it is the simplest
+       * one to use. Different ones are available for different use cases.
+       * The most powerful one is GtkBuilderListItemFactory which uses
+       * GtkBuilder .ui files, so it requires little code.
+       */
+      factory = gtk_signal_list_item_factory_new ();
+      g_signal_connect (factory, "setup", G_CALLBACK (setup_listitem_cb), NULL);
+      g_signal_connect (factory, "bind", G_CALLBACK (bind_listitem_cb), NULL);
+
+      /* And of course we need to set the data model. Here we call the function
+       * we wrote above that gives us the list of applications. Then we set
+       * it on the list widget.
+       * The list will now take items from the model and use the factory
+       * to create as many listitems as it needs to show itself to the user.
+       */
+      model = create_object_list ();
+
+      /* Wrap the model in a sort model that sorts the objects alphabetically.
+       */
+      sorter = GTK_SORTER (gtk_string_sorter_new (gtk_property_expression_new (GTK_TYPE_STRING_OBJECT, NULL, "string")));
+      model = G_LIST_MODEL (gtk_sort_list_model_new (model, sorter));
+
+      /* Create a sorter for the sections and tell the sort model about it
+       */
+      sorter = GTK_SORTER (gtk_string_sorter_new (gtk_cclosure_expression_new (G_TYPE_STRING, NULL, 0, NULL, G_CALLBACK (get_section), NULL, NULL)));
+      gtk_string_sorter_set_ignore_case (GTK_STRING_SORTER (sorter), FALSE);
+      gtk_sort_list_model_set_section_sorter (GTK_SORT_LIST_MODEL (model), sorter);
+      g_object_unref (sorter);
+
+      /* Create the list widget here.
+       */
+      list = gtk_list_view_new (GTK_SELECTION_MODEL (gtk_single_selection_new (model)), factory);
+
+      /* Set a factory for sections, otherwise the listview won't use sections.
+       */
+      factory = gtk_signal_list_item_factory_new ();
+      g_signal_connect (factory, "setup", G_CALLBACK (setup_section_listitem_cb), NULL);
+      g_signal_connect (factory, "bind", G_CALLBACK (bind_section_listitem_cb), NULL);
+      gtk_list_view_set_section_factory (GTK_LIST_VIEW (list), factory);
+      g_object_unref (factory);
+
+      /* List widgets should always be contained in a GtkScrolledWindow,
+       * because otherwise they might get too large or they might not
+       * be scrollable.
+       */
+      sw = gtk_scrolled_window_new ();
+      gtk_window_set_child (GTK_WINDOW (window), sw);
+      gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (sw), list);
+    }
+
+  if (!gtk_widget_get_visible (window))
+    gtk_widget_show (window);
+  else
+    gtk_window_destroy (GTK_WINDOW (window));
+
+  return window;
+}

demos/gtk-demo/meson.build

@@ -18,8 +18,9 @@ demos = files([
   'css_shadows.c',
   'cursors.c',
   'dialog.c',
-  'drawingarea.c',
   'dnd.c',
+  'drawingarea.c',
+  'dropdown.c',
   'editable_cells.c',
   'entry_completion.c',
   'entry_undo.c',
@@ -28,6 +29,7 @@ demos = files([
   'filtermodel.c',
   'fishbowl.c',
   'fixed.c',
+  'flowbox.c',
   'fontrendering.c',
   'frames.c',
   'gears.c',
@@ -46,20 +48,19 @@ demos = files([
   'links.c',
   'listbox.c',
   'listbox_controls.c',
-  'menu.c',
-  'flowbox.c',
   'list_store.c',
   'listview_applauncher.c',
   'listview_clocks.c',
   'listview_colors.c',
   'listview_filebrowser.c',
   'listview_minesweeper.c',
-  'dropdown.c',
+  'listview_objects.c',
   'listview_settings.c',
   'listview_ucd.c',
   'listview_weather.c',
   'listview_words.c',
   'markup.c',
+  'menu.c',
   'overlay.c',
   'overlay_decorative.c',
   'paint.c',