app: GimpAccelLabel now closure-free.

- New gimp_action_get_display_accels() added to GimpAction API to get directly
  the human-visible strings for actions.
- Also adding an "accels-changed" signal to GimpAction. As far as I can see,
  even though accelerators are now to be set on the GtkApplication, there seems
  to be no signals or properties to connect to at all on this class. So instead,
  let's do it on our GimpAction (which means we must absolutely not use
  gtk_application_set_accels_for_action()).
- GimpAccelLabel now uses the proper GimpAction API instead of accelerator
  closure which is a disappearing concept.

app/widgets/gimpaccellabel.c

@@ -56,12 +56,6 @@ static void   gimp_accel_label_get_property  (GObject             *object,
                                              GValue              *value,
                                              GParamSpec          *pspec);
 
-static void   gimp_accel_label_accel_changed (GtkAccelGroup       *accel_group,
-                                              guint                keyval,
-                                              GdkModifierType      modifier,
-                                              GClosure            *accel_closure,
-                                              GimpAccelLabel      *accel_label);
-
 static void   gimp_accel_label_update       (GimpAccelLabel      *accel_label);
 
 
@@ -144,67 +138,22 @@ gimp_accel_label_get_property (GObject    *object,
     }
 }
 
-static void
-gimp_accel_label_accel_changed (GtkAccelGroup   *accel_group,
-                                guint            keyval,
-                                GdkModifierType  modifier,
-                                GClosure        *accel_closure,
-                                GimpAccelLabel  *accel_label)
-{
-  if (accel_closure ==
-      gimp_action_get_accel_closure (accel_label->priv->action))
-    {
-      gimp_accel_label_update (accel_label);
-    }
-}
-
-static gboolean
-gimp_accel_label_update_accel_find_func (GtkAccelKey *key,
-                                         GClosure    *closure,
-                                         gpointer     data)
-{
-  return (GClosure *) data == closure;
-}
-
 static void
 gimp_accel_label_update (GimpAccelLabel *accel_label)
 {
-  GClosure      *accel_closure;
+  gchar **accels;
-  GtkAccelGroup *accel_group;
-  GtkAccelKey   *accel_key;
 
   gtk_label_set_label (GTK_LABEL (accel_label), NULL);
 
   if (! accel_label->priv->action)
     return;
 
-  accel_closure = gimp_action_get_accel_closure (accel_label->priv->action);
+  accels = gimp_action_get_display_accels (accel_label->priv->action);
 
-  if (! accel_closure)
+  if (accels && accels[0])
-    return;
+    gtk_label_set_label (GTK_LABEL (accel_label), accels[0]);
 
-  accel_group = gtk_accel_group_from_accel_closure (accel_closure);
+  g_strfreev (accels);
-
-  if (! accel_group)
-    return;
-
-  accel_key = gtk_accel_group_find (accel_group,
-                                    gimp_accel_label_update_accel_find_func,
-                                    accel_closure);
-
-  if (accel_key            &&
-      accel_key->accel_key &&
-      (accel_key->accel_flags & GTK_ACCEL_VISIBLE))
-    {
-      gchar *label;
-
-      label = gtk_accelerator_get_label (accel_key->accel_key,
-                                         accel_key->accel_mods);
-
-      gtk_label_set_label (GTK_LABEL (accel_label), label);
-
-      g_free (label);
-    }
 }
 
 
@@ -230,45 +179,16 @@ gimp_accel_label_set_action (GimpAccelLabel *accel_label,
   if (action != accel_label->priv->action)
     {
       if (accel_label->priv->action)
-        {
+        g_signal_handlers_disconnect_by_func (accel_label->priv->action,
-          GClosure *accel_closure;
+                                              gimp_accel_label_update,
-
-          accel_closure = gimp_action_get_accel_closure (
-            accel_label->priv->action);
-
-          if (accel_closure)
-            {
-              GtkAccelGroup *accel_group;
-
-              accel_group = gtk_accel_group_from_accel_closure (accel_closure);
-
-              g_signal_handlers_disconnect_by_func (
-                accel_group,
-                gimp_accel_label_accel_changed,
                                               accel_label);
-            }
-        }
 
       g_set_object (&accel_label->priv->action, action);
 
       if (accel_label->priv->action)
-        {
+        g_signal_connect_swapped (action, "accels-changed",
-          GClosure *accel_closure;
+                                  G_CALLBACK (gimp_accel_label_update),
-
-          accel_closure = gimp_action_get_accel_closure (
-            accel_label->priv->action);
-
-          if (accel_closure)
-            {
-              GtkAccelGroup *accel_group;
-
-              accel_group = gtk_accel_group_from_accel_closure (accel_closure);
-
-              g_signal_connect (accel_group, "accel-changed",
-                                G_CALLBACK (gimp_accel_label_accel_changed),
                                   accel_label);
-            }
-        }
 
       gimp_accel_label_update (accel_label);
 

app/widgets/gimpaction.c

@@ -45,6 +45,7 @@ enum
 {
   ACTIVATE,
   CHANGE_STATE,
+  ACCELS_CHANGED,
   LAST_SIGNAL
 };
 
@@ -105,6 +106,15 @@ gimp_action_default_init (GimpActionInterface *iface)
                   G_TYPE_NONE, 1,
                   G_TYPE_VARIANT);
 
+  action_signals[ACCELS_CHANGED] =
+    g_signal_new ("accels-changed",
+                  G_TYPE_FROM_INTERFACE (iface),
+                  G_SIGNAL_RUN_FIRST,
+                  G_STRUCT_OFFSET (GimpActionInterface, accels_changed),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 1,
+                  G_TYPE_STRV);
+
   g_object_interface_install_property (iface,
                                        g_param_spec_object ("context",
                                                             NULL, NULL,
@@ -407,6 +417,19 @@ gimp_action_connect_accelerator (GimpAction  *action)
   gtk_action_connect_accelerator ((GtkAction *) action);
 }
 
+/**
+ * gimp_action_set_accels:
+ * @action: a #GimpAction
+ * @accels: accelerators in the format understood by gtk_accelerator_parse().
+ *          The first accelerator is the main one.
+ *
+ * Set the accelerators to be associated with the given @action.
+ *
+ * Note that the #GimpAction API will emit the signal "accels-changed" whereas
+ * GtkApplication has no signal (that we could find) to connect to. It means we
+ * must always change accelerators with this function.
+ * Never use gtk_application_set_accels_for_action() directly!
+ */
 void
 gimp_action_set_accels (GimpAction   *action,
                         const gchar **accels)
@@ -426,6 +449,8 @@ gimp_action_set_accels (GimpAction   *action,
                                          detailed_action_name,
                                          accels);
   g_free (detailed_action_name);
+
+  g_signal_emit (action, action_signals[ACCELS_CHANGED], 0, accels);
 }
 
 /**
@@ -460,6 +485,47 @@ gimp_action_get_accels (GimpAction *action)
   return accels;
 }
 
+/**
+ * gimp_action_get_display_accels:
+ * @action: a #GimpAction
+ *
+ * Gets the accelerators that are currently associated with the given @action,
+ * in a format which can be presented to people on the GUI.
+ *
+ * Returns: (transfer full): accelerators for @action, as a %NULL-terminated
+ *          array. Free with g_strfreev() when no longer needed
+ */
+gchar **
+gimp_action_get_display_accels (GimpAction *action)
+{
+  gchar **accels;
+  gint    i;
+
+  g_return_val_if_fail (GIMP_IS_ACTION (action), NULL);
+
+  accels = gimp_action_get_accels (action);
+
+  for (i = 0; accels[i] != NULL; i++)
+    {
+      guint           accel_key = 0;
+      GdkModifierType accel_mods = 0;
+
+      gtk_accelerator_parse (accels[i], &accel_key, &accel_mods);
+
+      if (accel_key != 0 || accel_mods != 0)
+        {
+          gchar *accel;
+
+          accel = gtk_accelerator_get_label (accel_key, accel_mods);
+
+          g_free (accels[i]);
+          accels[i] = accel;
+        }
+    }
+
+  return accels;
+}
+
 GSList *
 gimp_action_get_proxies (GimpAction *action)
 {

app/widgets/gimpaction.h

@@ -51,6 +51,8 @@ struct _GimpActionInterface
                                         GVariant     *value);
   void          (* change_state)       (GimpAction   *action,
                                         GVariant     *value);
+  void          (* accels_changed)     (GimpAction   *action,
+                                        const gchar **accels);
 };
 
 
@@ -114,6 +116,7 @@ void          gimp_action_connect_accelerator (GimpAction    *action);
 void          gimp_action_set_accels          (GimpAction    *action,
                                                const gchar  **accels);
 gchar **      gimp_action_get_accels          (GimpAction    *action);
+gchar **      gimp_action_get_display_accels  (GimpAction    *action);
 
 GSList      * gimp_action_get_proxies         (GimpAction    *action);