atk/atkregistry.c

   1 /* ATK - Accessibility Toolkit
   2  * Copyright 2001 Sun Microsystems Inc.
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Library General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Library General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Library General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 #include "config.h"
  21
  22 #include "atkregistry.h"
  23 #include "atknoopobjectfactory.h"
  24
  25 /**
  26  * SECTION:atkregistry
  27  * @Short_description: An object used to store the GType of the
  28  * factories used to create an accessible object for an object of a
  29  * particular GType.
  30  * @Title:AtkRegistry
  31  *
  32  * The AtkRegistry is normally used to create appropriate ATK "peers"
  33  * for user interface components.  Application developers usually need
  34  * only interact with the AtkRegistry by associating appropriate ATK
  35  * implementation classes with GObject classes via the
  36  * atk_registry_set_factory_type call, passing the appropriate GType
  37  * for application custom widget classes.
  38  */
  39
  40 static AtkRegistry *default_registry = NULL;
  41
  42 static void              atk_registry_init           (AtkRegistry      *instance,
  43                                                       AtkRegistryClass *klass);
  44 static void              atk_registry_finalize       (GObject          *instance);
  45 static void              atk_registry_class_init     (AtkRegistryClass *klass);
  46 static AtkRegistry*      atk_registry_new            (void);
  47
  48 static gpointer parent_class = NULL;
  49
  50 GType
  51 atk_registry_get_type (void)
  52 {
  53   static GType type = 0;
  54
  55   if (!type)
  56     {
  57       static const GTypeInfo info =
  58       {
  59         sizeof (AtkRegistryClass),
  60         (GBaseInitFunc) NULL,                             /* base_init */
  61         (GBaseFinalizeFunc) NULL,                         /* base_finalize */
  62         (GClassInitFunc) atk_registry_class_init,         /* class_init */
  63         (GClassFinalizeFunc) NULL,                        /* class_finalize */
  64         NULL,                                             /* class_data */
  65         sizeof (AtkRegistry),                             /* instance size */
  66         0,                                                /* n_preallocs */
  67         (GInstanceInitFunc) atk_registry_init,            /* instance init */
  68         NULL                                              /* value table */
  69       };
  70
  71       type = g_type_register_static (G_TYPE_OBJECT, "AtkRegistry", &info, 0);
  72     }
  73
  74   return type;
  75 }
  76
  77 static void
  78 atk_registry_class_init (AtkRegistryClass *klass)
  79 {
  80   GObjectClass *object_class = (GObjectClass *) klass;
  81
  82   parent_class = g_type_class_peek_parent (klass);
  83
  84   object_class->finalize = atk_registry_finalize;
  85 }
  86
  87 static void
  88 atk_registry_init (AtkRegistry *instance, AtkRegistryClass *klass)
  89 {
  90   instance->factory_type_registry = g_hash_table_new ((GHashFunc) NULL,
  91                                                       (GEqualFunc) NULL);
  92   instance->factory_singleton_cache = g_hash_table_new ((GHashFunc) NULL,
  93                                                         (GEqualFunc) NULL);
  94 }
  95
  96 static AtkRegistry *
  97 atk_registry_new (void)
  98 {
  99   GObject *object;
 100
 101   object = g_object_new (ATK_TYPE_REGISTRY, NULL);
 102
 103   g_return_val_if_fail (ATK_IS_REGISTRY (object), NULL);
 104
 105   return (AtkRegistry *) object;
 106 }
 107
 108 static void
 109 atk_registry_finalize (GObject *object)
 110 {
 111   AtkRegistry *registry = ATK_REGISTRY (object);
 112
 113   g_hash_table_destroy (registry->factory_type_registry);
 114   g_hash_table_destroy (registry->factory_singleton_cache);
 115
 116   G_OBJECT_CLASS (parent_class)->finalize (object);
 117 }
 118
 119 /**
 120  * atk_registry_set_factory_type:
 121  * @registry: the #AtkRegistry in which to register the type association
 122  * @type: an #AtkObject type
 123  * @factory_type: an #AtkObjectFactory type to associate with @type.  Must
 124  * implement AtkObject appropriate for @type.
 125  *
 126  * Associate an #AtkObjectFactory subclass with a #GType. Note:
 127  * The associated @factory_type will thereafter be responsible for
 128  * the creation of new #AtkObject implementations for instances
 129  * appropriate for @type.
 130  **/
 131 void
 132 atk_registry_set_factory_type (AtkRegistry *registry,
 133                                GType type,
 134                                GType factory_type)
 135 {
 136   GType old_type;
 137   gpointer value;
 138   AtkObjectFactory *old_factory;
 139
 140   g_return_if_fail (ATK_IS_REGISTRY (registry));
 141
 142   value = g_hash_table_lookup (registry->factory_type_registry,
 143                                   (gpointer) type);
 144   old_type = (GType) value;
 145   if (old_type && old_type != factory_type)
 146     {
 147       g_hash_table_remove (registry->factory_type_registry,
 148                            (gpointer) type);
 149       /*
 150        * If the old factory was created, notify it that it has
 151        * been replaced, then free it.
 152        */
 153       old_factory = g_hash_table_lookup (registry->factory_singleton_cache,
 154                                          (gpointer) old_type);
 155       if (old_factory)
 156         {
 157           atk_object_factory_invalidate (old_factory);
 158           g_type_free_instance ((GTypeInstance *) old_factory);
 159         }
 160     }
 161   g_hash_table_insert (registry->factory_type_registry,
 162                        (gpointer) type,
 163                        (gpointer) factory_type);
 164 }
 165
 166 /**
 167  * atk_registry_get_factory_type:
 168  * @registry: an #AtkRegistry
 169  * @type: a #GType with which to look up the associated #AtkObjectFactory
 170  * subclass
 171  *
 172  * Provides a #GType indicating the #AtkObjectFactory subclass
 173  * associated with @type.
 174  *
 175  * Returns: a #GType associated with type @type
 176  **/
 177 GType
 178 atk_registry_get_factory_type (AtkRegistry *registry,
 179                                GType type)
 180 {
 181   GType factory_type;
 182   gpointer value;
 183
 184   /*
 185    * look up factory type in first hash;
 186    * if there isn't an explicitly registered factory type,
 187    * try inheriting one...
 188    */
 189   do {
 190     value =
 191         g_hash_table_lookup (registry->factory_type_registry,
 192                              (gpointer) type);
 193     type = g_type_parent (type);
 194     if (type == G_TYPE_INVALID)
 195       {
 196         break;
 197       }
 198   } while (value == NULL);
 199
 200   factory_type = (GType) value;
 201   return factory_type;
 202 }
 203
 204 /**
 205  * atk_registry_get_factory:
 206  * @registry: an #AtkRegistry
 207  * @type: a #GType with which to look up the associated #AtkObjectFactory
 208  *
 209  * Gets an #AtkObjectFactory appropriate for creating #AtkObjects
 210  * appropriate for @type.
 211  *
 212  * Returns: (transfer none): an #AtkObjectFactory appropriate for creating
 213  * #AtkObjects appropriate for @type.
 214  **/
 215 AtkObjectFactory*
 216 atk_registry_get_factory (AtkRegistry *registry,
 217                           GType type)
 218 {
 219   gpointer factory_pointer = NULL;
 220   GType factory_type;
 221
 222   factory_type = atk_registry_get_factory_type (registry, type);
 223
 224   if (factory_type == G_TYPE_INVALID)
 225   {
 226   /* Factory type has not been specified for this object type */
 227     static AtkObjectFactory* default_factory = NULL;
 228
 229     if (!default_factory)
 230       default_factory = atk_no_op_object_factory_new ();
 231
 232     return default_factory;
 233   }
 234
 235   /* ask second hashtable for instance of factory type */
 236   factory_pointer =
 237         g_hash_table_lookup (registry->factory_singleton_cache,
 238         (gpointer) factory_type);
 239
 240   /* if there isn't one already, create one and save it */
 241   if (factory_pointer == NULL)
 242     {
 243       factory_pointer = g_type_create_instance (factory_type);
 244       g_hash_table_insert (registry->factory_singleton_cache,
 245                            (gpointer) factory_type,
 246                            factory_pointer);
 247     }
 248
 249   return ATK_OBJECT_FACTORY (factory_pointer);
 250 }
 251
 252 /**
 253  * atk_get_default_registry:
 254  *
 255  * Gets a default implementation of the #AtkObjectFactory/type
 256  * registry.
 257  * Note: For most toolkit maintainers, this will be the correct
 258  * registry for registering new #AtkObject factories. Following
 259  * a call to this function, maintainers may call atk_registry_set_factory_type()
 260  * to associate an #AtkObjectFactory subclass with the GType of objects
 261  * for whom accessibility information will be provided.
 262  *
 263  * Returns: (transfer full): a default implementation of the
 264  * #AtkObjectFactory/type registry
 265  **/
 266 AtkRegistry*
 267 atk_get_default_registry (void)
 268 {
 269   if (!default_registry)
 270     {
 271       default_registry = atk_registry_new ();
 272     }
 273   return default_registry;
 274 }