st/entry: Use hint-actor as a11y description if possible

The hint-actor is used as a placeholder to explain the purpose
of an entry, but it currently isn't exposed to accessibility.

There is no good reason to not do that, so also use the actor
as described-by relationship, provided the actor is a label.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3179>
(cherry picked from commit bf497e42fb0b9b069d56df65f323a1bfd842ccb9)

diff --git a/src/st/st-entry.c b/src/st/st-entry.c
index 5ce08dfd247705c6fc0b44c3efea8ec57c8a13d3..8830d63003ee752656c70a25bb6820fd93988db1 100644 (file)
--- a/src/st/st-entry.c
+++ b/src/st/st-entry.c
@@ -121,6 +121,8 @@ G_DECLARE_FINAL_TYPE (StEntryAccessible,
                       ST, ENTRY_ACCESSIBLE,
                       StWidgetAccessible)
 
+static void update_hint_relation (StEntry *entry);
+
 static void
 st_entry_set_property (GObject      *gobject,
                        guint         prop_id,
@@ -1490,6 +1492,8 @@ st_entry_set_hint_actor (StEntry      *entry,
   st_entry_update_hint_visibility (entry);
   g_object_notify_by_pspec (G_OBJECT (entry), props[PROP_HINT_ACTOR]);
 
+  update_hint_relation (entry);
+
   clutter_actor_queue_relayout (CLUTTER_ACTOR (entry));
 }
 
@@ -1522,6 +1526,8 @@ st_entry_get_hint_actor (StEntry *entry)
 typedef struct _StEntryAccessible
 {
   StWidgetAccessible parent;
+
+  AtkObject *current_hint;
 } StEntryAccessible;
 
 G_DEFINE_FINAL_TYPE (StEntryAccessible, st_entry_accessible, ST_TYPE_WIDGET_ACCESSIBLE)
@@ -1532,6 +1538,16 @@ st_entry_accessible_init (StEntryAccessible *self)
   /* initialization done on AtkObject->initialize */
 }
 
+static void
+st_entry_accessible_dispose (GObject *object)
+{
+  StEntryAccessible *accessible = ST_ENTRY_ACCESSIBLE (object);
+
+  g_clear_object (&accessible->current_hint);
+
+  G_OBJECT_CLASS (st_entry_accessible_parent_class)->dispose (object);
+}
+
 static void
 st_entry_accessible_initialize (AtkObject *obj,
                                 gpointer   data)
@@ -1540,6 +1556,8 @@ st_entry_accessible_initialize (AtkObject *obj,
 
   /* StEntry is behaving as a ClutterText container */
   atk_object_set_role (obj, ATK_ROLE_PANEL);
+
+  update_hint_relation (ST_ENTRY (data));
 }
 
 static gint
@@ -1593,8 +1611,48 @@ static void
 st_entry_accessible_class_init (StEntryAccessibleClass *klass)
 {
   AtkObjectClass *atk_class = ATK_OBJECT_CLASS (klass);
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+
+  gobject_class->dispose = st_entry_accessible_dispose;
 
   atk_class->initialize = st_entry_accessible_initialize;
   atk_class->get_n_children = st_entry_accessible_get_n_children;
   atk_class->ref_child= st_entry_accessible_ref_child;
 }
+
+static void
+update_hint_relation (StEntry *entry)
+{
+  StEntryPrivate *priv;
+  AtkObject *accessible;
+  StEntryAccessible *entry_accessible;
+
+  priv = st_entry_get_instance_private (entry);
+
+  accessible = clutter_actor_get_accessible (priv->entry);
+  entry_accessible = ST_ENTRY_ACCESSIBLE (atk_object_get_parent (accessible));
+
+  if (entry_accessible->current_hint != NULL)
+    {
+      atk_object_remove_relationship (accessible,
+                                      ATK_RELATION_DESCRIBED_BY,
+                                      entry_accessible->current_hint);
+      atk_object_remove_relationship (entry_accessible->current_hint,
+                                      ATK_RELATION_DESCRIPTION_FOR,
+                                      accessible);
+      g_clear_object (&entry_accessible->current_hint);
+    }
+
+  if (ST_IS_LABEL (priv->hint_actor))
+    {
+      g_set_object (&entry_accessible->current_hint,
+                    clutter_actor_get_accessible (priv->hint_actor));
+
+      atk_object_add_relationship (accessible,
+                                   ATK_RELATION_DESCRIBED_BY,
+                                   entry_accessible->current_hint);
+      atk_object_add_relationship (entry_accessible->current_hint,
+                                   ATK_RELATION_DESCRIPTION_FOR,
+                                   accessible);
+    }
+}