a11y: add if applies ATK_RELATION_FLOWS_TO/FROM on EvPageAccessible

https://bugzilla.gnome.org/show_bug.cgi?id=724965

origin commit:
https://git.gnome.org/browse/evince/commit/?h=gnome-3-14&id=f6ae6b7

3 files changed, 58 insertions, 1 deletions

diff --git a/libview/ev-page-accessible.c b/libview/ev-page-accessible.c
index 60d07e33..77ae988f 100644
--- a/libview/ev-page-accessible.c
+++ b/libview/ev-page-accessible.c
@@ -125,6 +125,61 @@ ev_page_accessible_get_property (GObject    *object,
 	}
 }
 
+/*
+ * We redefine atk_class->ref_relation_set instead of just calling
+ * atk_object_add_relationship on ev_page_accessible_new because at
+ * that moment not all the pages could be created, being easier add
+ * the relation on demand.
+ */
+static AtkRelationSet *
+ev_page_accessible_ref_relation_set (AtkObject *accessible)
+{
+	gint n_pages;
+	EvPageAccessible *self;
+	AtkRelationSet *relation_set;
+	AtkObject *accessible_array[1];
+	AtkRelation *relation;
+
+	g_return_val_if_fail (EV_IS_PAGE_ACCESSIBLE (accessible), NULL);
+	self = EV_PAGE_ACCESSIBLE (accessible);
+
+	relation_set = ATK_OBJECT_CLASS (ev_page_accessible_parent_class)->ref_relation_set (accessible);
+	if (relation_set == NULL)
+		return NULL;
+
+	n_pages = ev_view_accessible_get_n_pages (self->priv->view_accessible);
+	if (n_pages == 0)
+		return relation_set;
+
+	if ((self->priv->page + 1) < n_pages && !atk_relation_set_contains (relation_set, ATK_RELATION_FLOWS_TO)) {
+		AtkObject *next_page;
+
+		next_page = atk_object_ref_accessible_child (ATK_OBJECT (self->priv->view_accessible),
+							     self->priv->page + 1);
+		accessible_array [0] = next_page;
+		relation = atk_relation_new (accessible_array, 1, ATK_RELATION_FLOWS_TO);
+		atk_relation_set_add (relation_set, relation);
+
+		g_object_unref (relation);
+		g_object_unref (next_page);
+	}
+
+	if (self->priv->page > 0 && !atk_relation_set_contains (relation_set, ATK_RELATION_FLOWS_FROM)) {
+		AtkObject *prev_page;
+
+		prev_page = atk_object_ref_accessible_child (ATK_OBJECT (self->priv->view_accessible),
+							     self->priv->page - 1);
+		accessible_array [0] = prev_page;
+		relation = atk_relation_new (accessible_array, 1, ATK_RELATION_FLOWS_FROM);
+		atk_relation_set_add (relation_set, relation);
+
+		g_object_unref (relation);
+		g_object_unref (prev_page);
+	}
+
+	return relation_set;
+}
+
 static void
 ev_page_accessible_class_init (EvPageAccessibleClass *klass)
 {
@@ -134,6 +189,7 @@ ev_page_accessible_class_init (EvPageAccessibleClass *klass)
         g_type_class_add_private (klass, sizeof (EvPageAccessiblePrivate));
 
 	atk_class->get_parent  = ev_page_accessible_get_parent;
+	atk_class->ref_relation_set = ev_page_accessible_ref_relation_set;
 
 	g_object_class->get_property = ev_page_accessible_get_property;
 	g_object_class->set_property = ev_page_accessible_set_property;
diff --git a/libview/ev-view-accessible.c b/libview/ev-view-accessible.c
index c350a7a6..3f448379 100644
--- a/libview/ev-view-accessible.c
+++ b/libview/ev-view-accessible.c
@@ -127,7 +127,7 @@ ev_view_accessible_initialize (AtkObject *obj,
 	atk_object_set_role (obj, ATK_ROLE_DOCUMENT_FRAME);
 }
 
-static gint
+gint
 ev_view_accessible_get_n_pages (EvViewAccessible *self)
 {
 	return self->priv->children == NULL ? 0 : self->priv->children->len;
diff --git a/libview/ev-view-accessible.h b/libview/ev-view-accessible.h
index df3ca317..9b62d347 100644
--- a/libview/ev-view-accessible.h
+++ b/libview/ev-view-accessible.h
@@ -52,6 +52,7 @@ GType      ev_view_accessible_get_type  (void);
 AtkObject *ev_view_accessible_new       (GtkWidget *widget);
 void       ev_view_accessible_set_model (EvViewAccessible *accessible,
                                          EvDocumentModel  *model);
+gint       ev_view_accessible_get_n_pages (EvViewAccessible *accessible);
 
 #endif  /* __EV_VIEW_ACCESSIBLE_H__ */