A minimal accessible implementation

To inform ATs about what is going on, implement AtkSelection,
and also emit ::active-descendant-changed. This seems enough
to make orca read 'filler' for each row (unless the row happens
to be just a label, in which case, it reads the label).
https://bugzilla.gnome.org/show_bug.cgi?id=692258

Makefile.am

@@ -12,7 +12,10 @@ AM_VALAFLAGS = \
 
 noinst_LTLIBRARIES = libegglistbox.la
 
-libegglistbox_la_SOURCES = egg-list-box.c egg-list-box.h
+libegglistbox_la_SOURCES = \
+	egg-list-box.c egg-list-box.h \
+	egg-list-box-accessible.c egg-list-box-accessible.h
+
 libegglistbox_la_LIBADD = $(LISTBOX_LIBS)
 
 noinst_PROGRAMS = test-list test-scrolled test-focus test-sel

egg-list-box-accessible.c

@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2013 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "egg-list-box.h"
+#include "egg-list-box-accessible.h"
+
+static void atk_selection_interface_init (AtkSelectionIface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (EggListBoxAccessible, egg_list_box_accessible, GTK_TYPE_CONTAINER_ACCESSIBLE,
+                         G_IMPLEMENT_INTERFACE (ATK_TYPE_SELECTION, atk_selection_interface_init))
+
+static void
+egg_list_box_accessible_init (EggListBoxAccessible *accessible)
+{
+}
+
+static void
+egg_list_box_accessible_class_init (EggListBoxAccessibleClass *klass)
+{
+}
+
+static gboolean
+egg_list_box_accessible_add_selection (AtkSelection *selection,
+                                       gint          idx)
+{
+  GtkWidget *box;
+  GList *children;
+  GtkWidget *child;
+
+  box = gtk_accessible_get_widget (GTK_ACCESSIBLE (selection));
+  if (box == NULL)
+    return FALSE;
+
+  children = gtk_container_get_children (GTK_CONTAINER (box));
+  child = g_list_nth_data (children, idx);
+  g_list_free (children);
+  if (child)
+    {
+      egg_list_box_select_child (EGG_LIST_BOX (box), child);
+      return TRUE;
+    }
+  return FALSE;
+}
+
+static gboolean
+egg_list_box_accessible_clear_selection (AtkSelection *selection)
+{
+  GtkWidget *box;
+
+  box = gtk_accessible_get_widget (GTK_ACCESSIBLE (selection));
+  if (box == NULL)
+    return FALSE;
+
+  egg_list_box_select_child (EGG_LIST_BOX (box), NULL);
+  return TRUE;
+}
+
+static AtkObject *
+egg_list_box_accessible_ref_selection (AtkSelection *selection,
+                                       gint          idx)
+{
+  GtkWidget *box;
+  GtkWidget *widget;
+  AtkObject *accessible;
+
+  if (idx != 0)
+    return NULL;
+
+  box = gtk_accessible_get_widget (GTK_ACCESSIBLE (selection));
+  if (box == NULL)
+    return NULL;
+
+  widget = egg_list_box_get_selected_child (EGG_LIST_BOX (box));
+  if (widget == NULL)
+    return NULL;
+
+  accessible = gtk_widget_get_accessible (widget);
+  g_object_ref (accessible);
+  return accessible;
+}
+
+static gint
+egg_list_box_accessible_get_selection_count (AtkSelection *selection)
+{
+  GtkWidget *box;
+  GtkWidget *widget;
+
+  box = gtk_accessible_get_widget (GTK_ACCESSIBLE (selection));
+  if (box == NULL)
+    return 0;
+
+  widget = egg_list_box_get_selected_child (EGG_LIST_BOX (box));
+  if (widget == NULL)
+    return 0;
+
+  return 1;
+}
+
+static gboolean
+egg_list_box_accessible_is_child_selected (AtkSelection *selection,
+                                           gint          idx)
+{
+  GtkWidget *box;
+  GtkWidget *widget;
+  GList *children;
+  GtkWidget *child;
+
+  box = gtk_accessible_get_widget (GTK_ACCESSIBLE (selection));
+  if (box == NULL)
+    return FALSE;
+
+  widget = egg_list_box_get_selected_child (EGG_LIST_BOX (box));
+  if (widget == NULL)
+    return FALSE;
+
+  children = gtk_container_get_children (GTK_CONTAINER (box));
+  child = g_list_nth_data (children, idx);
+  g_list_free (children);
+  return child == widget;
+}
+
+static void atk_selection_interface_init (AtkSelectionIface *iface)
+{
+  iface->add_selection = egg_list_box_accessible_add_selection;
+  iface->clear_selection = egg_list_box_accessible_clear_selection;
+  iface->ref_selection = egg_list_box_accessible_ref_selection;
+  iface->get_selection_count = egg_list_box_accessible_get_selection_count;
+  iface->is_child_selected = egg_list_box_accessible_is_child_selected;
+}
+
+void
+_egg_list_box_accessible_update_selected (EggListBox *box,
+                                          GtkWidget  *child)
+{
+  AtkObject *accessible;
+  accessible = gtk_widget_get_accessible (GTK_WIDGET (box));
+  g_signal_emit_by_name (accessible, "selection-changed");
+}
+
+void
+_egg_list_box_accessible_update_cursor (EggListBox *box,
+                                        GtkWidget  *child)
+{
+  AtkObject *accessible;
+  AtkObject *descendant;
+  accessible = gtk_widget_get_accessible (GTK_WIDGET (box));
+  descendant = child ? gtk_widget_get_accessible (child) : NULL;
+  g_signal_emit_by_name (accessible, "active-descendant-changed", descendant);
+}

egg-list-box-accessible.h

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2013 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __EGG_LIST_BOX_ACCESSIBLE_H__
+#define __EGG_LIST_BOX_ACCESSIBLE_H__
+
+#include <gtk/gtk-a11y.h>
+
+G_BEGIN_DECLS
+
+#define EGG_TYPE_LIST_BOX_ACCESSIBLE                   (egg_list_box_accessible_get_type ())
+#define EGG_LIST_BOX_ACCESSIBLE(obj)                   (G_TYPE_CHECK_INSTANCE_CAST ((obj), EGG_TYPE_LIST_BOX_ACCESSIBLE, EggListBoxAccessible))
+#define EGG_LIST_BOX_ACCESSIBLE_CLASS(klass)           (G_TYPE_CHECK_CLASS_CAST ((klass), EGG_TYPE_LIST_BOX_ACCESSIBLE, EggListBoxAccessibleClass))
+#define EGG_IS_LIST_BOX_ACCESSIBLE(obj)                (G_TYPE_CHECK_INSTANCE_TYPE ((obj), EGG_TYPE_LIST_BOX_ACCESSIBLE))
+#define EGG_IS_LIST_BOX_ACCESSIBLE_CLASS(klass)        (G_TYPE_CHECK_CLASS_TYPE ((klass), EGG_TYPE_LIST_BOX_ACCESSIBLE))
+#define EGG_LIST_BOX_ACCESSIBLE_GET_CLASS(obj)         (G_TYPE_INSTANCE_GET_CLASS ((obj), EGG_TYPE_LIST_BOX_ACCESSIBLE, EggListBoxAccessibleClass))
+
+typedef struct _EggListBoxAccessible        EggListBoxAccessible;
+typedef struct _EggListBoxAccessibleClass   EggListBoxAccessibleClass;
+typedef struct _EggListBoxAccessiblePrivate EggListBoxAccessiblePrivate;
+
+struct _EggListBoxAccessible
+{
+  GtkContainerAccessible parent;
+
+  EggListBoxAccessiblePrivate *priv;
+};
+
+struct _EggListBoxAccessibleClass
+{
+  GtkContainerAccessibleClass parent_class;
+};
+
+GType egg_list_box_accessible_get_type (void);
+
+void _egg_list_box_accessible_update_selected (EggListBox *box, GtkWidget *child);
+void _egg_list_box_accessible_update_cursor   (EggListBox *box, GtkWidget *child);
+
+G_END_DECLS
+
+#endif /* __EGG_LIST_BOX_ACCESSIBLE_H__ */

egg-list-box.c

@@ -26,6 +26,7 @@
 #include <gobject/gvaluecollector.h>
 
 #include "egg-list-box.h"
+#include "egg-list-box-accessible.h"
 
 /* This already exists in gtk as _gtk_marshal_VOID__ENUM_INT, inline it here for now
    to avoid separate marshallers file */
@@ -293,6 +294,8 @@ egg_list_box_class_init (EggListBoxClass *klass)
 
   g_type_class_add_private (klass, sizeof (EggListBoxPrivate));
 
+  gtk_widget_class_set_accessible_type (widget_class, EGG_TYPE_LIST_BOX_ACCESSIBLE);
+
   object_class->finalize = egg_list_box_finalize;
   widget_class->enter_notify_event = egg_list_box_real_enter_notify_event;
   widget_class->leave_notify_event = egg_list_box_real_leave_notify_event;
@@ -709,6 +712,7 @@ egg_list_box_update_cursor (EggListBox *list_box,
 				 priv->cursor_child->y + allocation.y,
 				 priv->cursor_child->y + allocation.y + priv->cursor_child->height);
   }
+  _egg_list_box_accessible_update_cursor (list_box, child ? child->widget : NULL);
 }
 
 static void
@@ -725,6 +729,7 @@ egg_list_box_update_selected (EggListBox *list_box,
 		     (priv->selected_child != NULL) ? priv->selected_child->widget : NULL);
       gtk_widget_queue_draw (GTK_WIDGET (list_box));
     }
+  _egg_list_box_accessible_update_selected (list_box, child ? child->widget : NULL);
   if (child != NULL)
     egg_list_box_update_cursor (list_box, child);
 }