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().

3 files changed, 108 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
@@ -73,6 +131,37 @@ atk_plug_new (void)
 }
 
 /**
+ * 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..ec5bc59 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_2_36
+void          atk_plug_set_child (AtkPlug *plug, AtkObject *child);
 ATK_AVAILABLE_IN_ALL
-gchar*        atk_plug_get_id  (AtkPlug* plug);
+gchar*        atk_plug_get_id    (AtkPlug* plug);
 
 G_END_DECLS
 
diff --git a/atk/atkversion.h.in b/atk/atkversion.h.in
index 36946db..78dc6e2 100644
--- a/atk/atkversion.h.in
+++ b/atk/atkversion.h.in
@@ -400,6 +400,20 @@
 # define ATK_AVAILABLE_IN_2_30                 _ATK_EXTERN
 #endif
 
+#if ATK_VERSION_MIN_REQUIRED >= ATK_VERSION_2_36
+# define ATK_DEPRECATED_IN_2_36                ATK_DEPRECATED
+# define ATK_DEPRECATED_IN_2_36_FOR(f)         ATK_DEPRECATED_FOR(f)
+#else
+# define ATK_DEPRECATED_IN_2_36                _ATK_EXTERN
+# define ATK_DEPRECATED_IN_2_36_FOR(f)         _ATK_EXTERN
+#endif
+
+#if ATK_VERSION_MAX_ALLOWED < ATK_VERSION_2_36
+# define ATK_AVAILABLE_IN_2_36                 ATK_UNAVAILABLE(2, 36)
+#else
+# define ATK_AVAILABLE_IN_2_36                 _ATK_EXTERN
+#endif
+
 ATK_AVAILABLE_IN_2_8
 guint atk_get_major_version (void) G_GNUC_CONST;
 ATK_AVAILABLE_IN_2_8