[atk/plug_child] atkplug: Add atk_plug_set_child

[Samuel Thibault <sthibaul src gnome org>]

commit c4c00d439cfb6e75d961f723a9e52ec56cf05856
Author: Samuel Thibault <samuel thibault ens-lyon org>
Date:   Fri Aug 23 18:30:42 2019 +0200

    atkplug: Add atk_plug_set_child
    
    As discussed on
    
    https://mail.gnome.org/archives/gnome-accessibility-devel/2019-August/msg00001.html
    
    In some cases, one can not use the AtkPlug type directly as accessible
    object for the toplevel widget of the application. For instance in the gtk
    case, GtkPlugAccessible can not inherit both from GtkWindowAccessible and
    from AtkPlug. In such a case, one can create, in addition to the standard
    accessible object for the toplevel widget, an AtkPlug object, and make the
    former the child of the latter by calling atk_plug_set_child().

 atk/atkplug.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 atk/atkplug.h |  6 ++--
 2 files changed, 94 insertions(+), 3 deletions(-)
---
diff --git a/atk/atkplug.c b/atk/atkplug.c
index ceb3e5d..ddd86ed 100644
--- a/atk/atkplug.c
+++ b/atk/atkplug.c
@@ -34,8 +34,57 @@
 
 static void atk_component_interface_init (AtkComponentIface *iface);
 
+typedef struct {
+  AtkObject *child;
+} AtkPlugPrivate;
+
+static gint AtkPlug_private_offset;
+
 G_DEFINE_TYPE_WITH_CODE (AtkPlug, atk_plug, ATK_TYPE_OBJECT,
-                         G_IMPLEMENT_INTERFACE (ATK_TYPE_COMPONENT, atk_component_interface_init))
+                         G_IMPLEMENT_INTERFACE (ATK_TYPE_COMPONENT, atk_component_interface_init)
+                         G_ADD_PRIVATE(AtkPlug))
+
+static AtkObject*
+atk_plug_ref_child (AtkObject *obj, int i)
+{
+  AtkPlugPrivate *private = atk_plug_get_instance_private (ATK_PLUG (obj));
+  AtkObject *child;
+
+  if (i != 0)
+    return NULL;
+
+  child = private->child;
+
+  if (child == NULL)
+    return NULL;
+
+  return g_object_ref (child);
+}
+
+static int
+atk_plug_get_n_children (AtkObject *obj)
+{
+  AtkPlugPrivate *private = atk_plug_get_instance_private (ATK_PLUG (obj));
+
+  if (private->child == NULL)
+    return 0;
+
+  return 1;
+}
+
+static AtkStateSet*
+atk_plug_ref_state_set (AtkObject *obj)
+{
+  AtkPlugPrivate *private = atk_plug_get_instance_private (ATK_PLUG (obj));
+  AtkObject *child;
+
+  child = private->child;
+
+  if (child == NULL)
+    return NULL;
+
+  return atk_object_ref_state_set (child);
+}
 
 static void
 atk_plug_init (AtkPlug* obj)
@@ -49,7 +98,16 @@ atk_plug_init (AtkPlug* obj)
 static void
 atk_plug_class_init (AtkPlugClass* klass)
 {
+  AtkObjectClass *class = ATK_OBJECT_CLASS (klass);
+
+  if (AtkPlug_private_offset != 0)
+    g_type_class_adjust_private_offset (klass, &AtkPlug_private_offset);
+
   klass->get_object_id = NULL;
+
+  class->get_n_children = atk_plug_get_n_children;
+  class->ref_child      = atk_plug_ref_child;
+  class->ref_state_set  = atk_plug_ref_state_set;
 }
 
 static void
@@ -72,6 +130,37 @@ atk_plug_new (void)
   return g_object_new (ATK_TYPE_PLUG, NULL);
 }
 
+/**
+ * atk_plug_set_child:
+ * @plug: an #AtkPlug to be set as accessible parent of @child.
+ * @child: an #AtkObject to be set as accessible child of @plug.
+ *
+ * Sets @child as accessible child of @plug and @plug as accessible parent of
+ * @child. @child can be NULL.
+ *
+ * In some cases, one can not use the AtkPlug type directly as accessible
+ * object for the toplevel widget of the application. For instance in the gtk
+ * case, GtkPlugAccessible can not inherit both from GtkWindowAccessible and
+ * from AtkPlug. In such a case, one can create, in addition to the standard
+ * accessible object for the toplevel widget, an AtkPlug object, and make the
+ * former the child of the latter by calling atk_plug_set_child().
+ *
+ * Since: 2.35.0
+ */
+void
+atk_plug_set_child (AtkPlug *plug, AtkObject *child)
+{
+  AtkPlugPrivate *private = atk_plug_get_instance_private (plug);
+
+  if (private->child)
+    atk_object_set_parent (private->child, NULL);
+
+  private->child = child;
+
+  if (child)
+    atk_object_set_parent (child, ATK_OBJECT(plug));
+}
+
 /**
  * atk_plug_get_id:
  * @plug: an #AtkPlug
diff --git a/atk/atkplug.h b/atk/atkplug.h
index b1d83ff..39244ff 100644
--- a/atk/atkplug.h
+++ b/atk/atkplug.h
@@ -57,9 +57,11 @@ struct _AtkPlugClass
 };
 
 ATK_AVAILABLE_IN_ALL
-AtkObject*    atk_plug_new     (void);
+AtkObject*    atk_plug_new       (void);
 ATK_AVAILABLE_IN_ALL
-gchar*        atk_plug_get_id  (AtkPlug* plug);
+void          atk_plug_set_child (AtkPlug *plug, AtkObject *child);
+ATK_AVAILABLE_IN_ALL
+gchar*        atk_plug_get_id    (AtkPlug* plug);
 
 G_END_DECLS