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Class/Instance Initializers

You will have to set up a class initializer for the GObject if your AtkObject implementation either:

  1. Redefines any function calls defined by the object's parent. This is typically necessary when an object needs to implement a function like atk_object_get_n_accessible_children(). This is necessary if the object has children, but they are not represented with widgets.

  2. Requires a parent->init, parent->notify_gtk, or parent->finalize function.

    1. parent->init

      A parent->init() function may be necessary if the ATK implementation needs to do either of the following:

      1. Cache any data obtained from a backing GTK widget.
      2. Listen to any signals from the backing GTK widget.

    2. parent->notify_gtk

      If the ATK implementation needs to listen to any property notifications on the backing GTK object, a parent->notify_gtk() function may be necessary. For example:

      Example 1-7 A custom notify_gtk() function
      void 
myatkimp_mytype_real_notify_gtk (GObject    *obj, 
                                 GParamSpec *pspec) 
{ 
   GtkWidget *widget = GTK_WIDGET (obj); 
   AtkObject* atk_obj = gtk_widget_get_accessible (widget); 

   if (strcmp (pspec->name, "property-of-interest") == 0) 
   { 
      /* Handle the property change. */ 
   } 
   else 
   { 
      parent_class->notify_gtk (obj, pspec); 
   } 
}

    3. parent->finalize

      If it is necessary to free any data when a GObject instance is destroyed, then a finalize() function is needed to free the memory. For example:

      Example 1-8 A custom finalize() function
      void 
myatkimp_mytype_finalize (GObject *object) 
{ 
   MyAtkimpMyType *my_type = MYATKIMP_MYTYPE (object); 

   g_object_unref (my_type->cached_value); 
   G_OBJECT_CLASS (parent_class)->finalize (object); 
}
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