Add IdoActionHelper

This class contains some functionality that all menu items that are bound to
an action need. It listens for action additions and removals, changes in
enabled state, and state changes. It is _not_ intended to be used by specific
menu items, but rather as the glue in IdoMenuItemFactory, to bind a widget to
an action.

An alternative way to reach the same goal is to have an IdoMenuItem base class
which contains the common functionality. This would have required touching
all existing menu items (slider, user menu item, media player items) and
would have added more complexity to them.

It is similar in spirit to GtkActionHelper (a private class in gtk), but very
different in API and implementation.

1 files changed, 364 insertions, 0 deletions

diff --git a/src/idoactionhelper.c b/src/idoactionhelper.c
new file mode 100644
index 0000000..b68423a
--- /dev/null
+++ b/src/idoactionhelper.c
@@ -0,0 +1,364 @@
+/*
+* Copyright 2013 Canonical Ltd.
+*
+* This program is free software: you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 3, as published
+* by the Free Software Foundation.
+*
+* This program is distributed in the hope that it will be useful, but
+* WITHOUT ANY WARRANTY; without even the implied warranties of
+* MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
+* PURPOSE.  See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along
+* with this program.  If not, see <http://www.gnu.org/licenses/>.
+*
+* Authors:
+*     Lars Uebernickel <lars.uebernickel@canonical.com>
+*/
+
+#include "idoactionhelper.h"
+
+typedef GObjectClass IdoActionHelperClass;
+
+struct _IdoActionHelper
+{
+  GObject parent;
+
+  GtkWidget *widget;
+  GActionGroup *actions;
+  gchar *action_name;
+  GVariant *action_target;
+};
+
+G_DEFINE_TYPE (IdoActionHelper, ido_action_helper, G_TYPE_OBJECT)
+
+enum
+{
+  PROP_0,
+  PROP_WIDGET,
+  PROP_ACTION_GROUP,
+  PROP_ACTION_NAME,
+  PROP_ACTION_TARGET,
+  NUM_PROPERTIES
+};
+
+enum
+{
+  ACTION_STATE_CHANGED,
+  NUM_SIGNALS
+};
+
+static GParamSpec *properties[NUM_PROPERTIES];
+static guint signals[NUM_SIGNALS];
+
+static void
+ido_action_helper_action_added (GActionGroup *actions,
+                                const gchar  *action_name,
+                                gpointer      user_data)
+{
+  IdoActionHelper *helper = user_data;
+  gboolean enabled;
+  GVariant *state;
+
+  if (!g_str_equal (action_name, helper->action_name))
+    return;
+
+  if (g_action_group_query_action (actions, action_name,
+                                   &enabled, NULL, NULL, NULL, &state))
+    {
+      gtk_widget_set_sensitive (helper->widget, enabled);
+
+      if (state)
+        {
+          g_signal_emit (helper, signals[ACTION_STATE_CHANGED], 0, state);
+          g_variant_unref (state);
+        }
+    }
+  else
+    {
+      gtk_widget_set_sensitive (helper->widget, FALSE);
+    }
+}
+
+static void
+ido_action_helper_action_removed (GActionGroup *action_group,
+                                  gchar        *action_name,
+                                  gpointer      user_data)
+{
+  IdoActionHelper *helper = user_data;
+
+  if (g_str_equal (action_name, helper->action_name))
+    gtk_widget_set_sensitive (helper->widget, FALSE);
+}
+
+static void
+ido_action_helper_action_enabled_changed (GActionGroup *action_group,
+                                          gchar        *action_name,
+                                          gboolean      enabled,
+                                          gpointer      user_data)
+{
+  IdoActionHelper *helper = user_data;
+
+  if (g_str_equal (action_name, helper->action_name))
+    gtk_widget_set_sensitive (helper->widget, enabled);
+}
+
+static void
+ido_action_helper_action_state_changed (GActionGroup *action_group,
+                                        gchar        *action_name,
+                                        GVariant     *value,
+                                        gpointer      user_data)
+{
+  IdoActionHelper *helper = user_data;
+
+  if (g_str_equal (action_name, helper->action_name))
+    g_signal_emit (helper, signals[ACTION_STATE_CHANGED], 0, value);
+}
+
+static gboolean
+call_action_added (gpointer user_data)
+{
+  IdoActionHelper *helper = user_data;
+
+  ido_action_helper_action_added (helper->actions, helper->action_name, helper);
+
+  return G_SOURCE_REMOVE;
+}
+
+static void
+ido_action_helper_constructed (GObject *object)
+{
+  IdoActionHelper *helper = IDO_ACTION_HELPER (object);
+
+  g_signal_connect (helper->actions, "action-added",
+                    G_CALLBACK (ido_action_helper_action_added), helper);
+  g_signal_connect (helper->actions, "action-removed",
+                    G_CALLBACK (ido_action_helper_action_removed), helper);
+  g_signal_connect (helper->actions, "action-enabled-changed",
+                    G_CALLBACK (ido_action_helper_action_enabled_changed), helper);
+  g_signal_connect (helper->actions, "action-state-changed",
+                    G_CALLBACK (ido_action_helper_action_state_changed), helper);
+
+  if (g_action_group_has_action (helper->actions, helper->action_name))
+    {
+      /* call action_added in an idle, so that we don't fire the
+       * state-changed signal during construction (nobody could have
+       * connected by then).
+       */
+      g_idle_add (call_action_added, helper);
+    }
+
+  G_OBJECT_CLASS (ido_action_helper_parent_class)->constructed (object);
+}
+
+static void
+ido_action_helper_get_property (GObject    *object,
+                                guint       id,
+                                GValue     *value,
+                                GParamSpec *pspec)
+{
+  IdoActionHelper *helper = IDO_ACTION_HELPER (object);
+
+  switch (id)
+    {
+    case PROP_WIDGET:
+      g_value_set_object (value, helper->widget);
+      break;
+
+    case PROP_ACTION_GROUP:
+      g_value_set_object (value, helper->actions);
+      break;
+
+    case PROP_ACTION_NAME:
+      g_value_set_string (value, helper->action_name);
+      break;
+
+    case PROP_ACTION_TARGET:
+      g_value_set_variant (value, helper->action_target);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, id, pspec);
+    }
+}
+
+static void
+ido_action_helper_set_property (GObject      *object,
+                                guint         id,
+                                const GValue *value,
+                                GParamSpec   *pspec)
+{
+  IdoActionHelper *helper = IDO_ACTION_HELPER (object);
+
+  switch (id)
+    {
+    case PROP_WIDGET: /* construct-only */
+      helper->widget = g_value_dup_object (value);
+      break;
+
+    case PROP_ACTION_GROUP: /* construct-only */
+      helper->actions = g_value_dup_object (value);
+      break;
+
+    case PROP_ACTION_NAME: /* construct-only */
+      helper->action_name = g_value_dup_string (value);
+      break;
+
+    case PROP_ACTION_TARGET: /* construct-only */
+      helper->action_target = g_value_dup_variant (value);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, id, pspec);
+    }
+}
+
+static void
+ido_action_helper_finalize (GObject *object)
+{
+  IdoActionHelper *helper = IDO_ACTION_HELPER (object);
+
+  g_object_unref (helper->widget);
+
+  g_signal_handlers_disconnect_by_data (helper->actions, helper);
+  g_object_unref (helper->actions);
+
+  g_free (helper->action_name);
+
+  if (helper->action_target)
+    g_variant_unref (helper->action_target);
+
+  G_OBJECT_CLASS (ido_action_helper_parent_class)->finalize (object);
+}
+
+static void
+ido_action_helper_class_init (IdoActionHelperClass *class)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (class);
+
+  object_class->constructed = ido_action_helper_constructed;
+  object_class->get_property = ido_action_helper_get_property;
+  object_class->set_property = ido_action_helper_set_property;
+  object_class->finalize = ido_action_helper_finalize;
+
+  signals[ACTION_STATE_CHANGED] = g_signal_new ("action-state-changed",
+                                                IDO_TYPE_ACTION_HELPER,
+                                                G_SIGNAL_RUN_FIRST,
+                                                0, NULL, NULL,
+                                                g_cclosure_marshal_VOID__VARIANT,
+                                                G_TYPE_NONE, 1, G_TYPE_VARIANT);
+
+  properties[PROP_WIDGET] = g_param_spec_object ("widget", "", "",
+                                                 GTK_TYPE_WIDGET,
+                                                 G_PARAM_CONSTRUCT_ONLY |
+                                                 G_PARAM_READWRITE |
+                                                 G_PARAM_STATIC_STRINGS);
+
+  properties[PROP_ACTION_GROUP] = g_param_spec_object ("action-group", "", "",
+                                                       G_TYPE_ACTION_GROUP,
+                                                       G_PARAM_CONSTRUCT_ONLY |
+                                                       G_PARAM_READWRITE |
+                                                       G_PARAM_STATIC_STRINGS);
+
+  properties[PROP_ACTION_NAME] = g_param_spec_string ("action-name", "", "", NULL,
+                                                      G_PARAM_CONSTRUCT_ONLY |
+                                                      G_PARAM_READWRITE |
+                                                      G_PARAM_STATIC_STRINGS);
+
+  properties[PROP_ACTION_TARGET] = g_param_spec_variant ("action-target", "", "",
+                                                         G_VARIANT_TYPE_ANY, NULL,
+                                                         G_PARAM_CONSTRUCT_ONLY |
+                                                         G_PARAM_READWRITE |
+                                                         G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (object_class, NUM_PROPERTIES, properties);
+}
+
+static void
+ido_action_helper_init (IdoActionHelper *helper)
+{
+}
+
+/**
+ * ido_action_helper_new:
+ * @widget: a #GtkWidget
+ * @action_group: a #GActionGroup
+ * @action_name: the name of an action in @action_group
+ * @target: the target of the action
+ *
+ * Creates a new #IdoActionHelper. This helper ties @widget to an action
+ * (and a target), and performs some common tasks:
+ *
+ * @widget will be set to insensitive whenever @action_group does not
+ * contain an action with the name @action_name, or the action with that
+ * name is disabled.
+ *
+ * Also, the helper emits the "action-state-changed" signal whenever the
+ * widget must be updated from the action's state. This includes once
+ * when the action was added, and every time the action changes its
+ * state.
+ *
+ * Returns: (transfer full): a new #IdoActionHelper
+ */
+IdoActionHelper *
+ido_action_helper_new (GtkWidget    *widget,
+                       GActionGroup *action_group,
+                       const gchar  *action_name,
+                       GVariant     *target)
+{
+  g_return_val_if_fail (widget != NULL, NULL);
+  g_return_val_if_fail (action_group != NULL, NULL);
+  g_return_val_if_fail (action_name != NULL, NULL);
+
+  return g_object_new (IDO_TYPE_ACTION_HELPER,
+                       "widget", widget,
+                       "action-group", action_group,
+                       "action-name", action_name,
+                       "action-target", target,
+                       NULL);
+}
+
+/**
+ * ido_action_helper_get_widget:
+ * @helper: an #IdoActionHelper
+ *
+ * Returns: (transfer none): the #GtkWidget associated with @helper
+ */
+GtkWidget *
+ido_action_helper_get_widget (IdoActionHelper *helper)
+{
+  g_return_val_if_fail (IDO_IS_ACTION_HELPER (helper), NULL);
+
+  return helper->widget;
+}
+
+/**
+ * ido_action_helper_get_action_target:
+ * @helper: an #IdoActionHelper
+ *
+ * Returns: (transfer none): the action target that was set in
+ * ido_action_helper_new() as a #GVariant
+ */
+GVariant *
+ido_action_helper_get_action_target (IdoActionHelper *helper)
+{
+  g_return_val_if_fail (IDO_IS_ACTION_HELPER (helper), NULL);
+
+  return helper->action_target;
+}
+
+/**
+ * ido_action_helper_activate:
+ * @helper: an #IdoActionHelper
+ *
+ * Activates the action that is associated with this helper.
+ */
+void
+ido_action_helper_activate (IdoActionHelper *helper)
+{
+  g_return_if_fail (IDO_IS_ACTION_HELPER (helper));
+
+  if (helper->actions && helper->action_name)
+    g_action_group_activate_action (helper->actions, helper->action_name, helper->action_target);
+}