introduce private GtkActionHelper

The current process of implementing GActionObserver is annoying and the
GSimpleActionObserver interface leaves a lot to be desired.  Introduce a
new class, GtkActionHelper that gives you pretty much everything you'd
want to do as an implementor of GtkActionable.

The GtkActionHelper also features an "application" mode that is not
associated with a particular GtkWidget but rather with whatever widget
happens to be the active window of the given GtkApplication at a
particular point in time.  This will be useful for the Mac OS menubar.

1 files changed, 631 insertions, 0 deletions

diff --git a/gtk/gtkactionhelper.c b/gtk/gtkactionhelper.c
new file mode 100644
index 0000000000..6047a43cf9
--- /dev/null
+++ b/gtk/gtkactionhelper.c
@@ -0,0 +1,631 @@
+/*
+ * Copyright © 2012 Canonical Limited
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * licence or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Ryan Lortie <desrt@desrt.ca>
+ */
+
+#include "gtkactionhelper.h"
+#include "gactionobservable.h"
+
+#include "gtkwidget.h"
+#include "gtkwidgetprivate.h"
+
+#include <string.h>
+
+typedef struct
+{
+  GActionGroup *group;
+
+  GHashTable *watchers;
+} GtkActionHelperGroup;
+
+static void             gtk_action_helper_action_added                  (GtkActionHelper    *helper,
+                                                                         gboolean            enabled,
+                                                                         const GVariantType *parameter_type,
+                                                                         GVariant           *state,
+                                                                         gboolean            should_emit_signals);
+
+static void             gtk_action_helper_action_removed                (GtkActionHelper    *helper);
+
+static void             gtk_action_helper_action_enabled_changed        (GtkActionHelper    *helper,
+                                                                         gboolean            enabled);
+
+static void             gtk_action_helper_action_state_changed          (GtkActionHelper    *helper,
+                                                                         GVariant           *new_state);
+
+typedef GObjectClass GtkActionHelperClass;
+
+struct _GtkActionHelper
+{
+  GObject parent_instance;
+
+  GtkApplication *application;
+  GtkWidget *widget;
+
+  GtkActionHelperGroup *group;
+
+  GActionMuxer *action_context;
+  gchar *action_name;
+
+  GVariant *target;
+
+  GtkActionHelperRole role;
+  gboolean can_activate;
+  gboolean enabled;
+  gboolean active;
+
+  gint reporting;
+};
+
+enum
+{
+  PROP_0,
+  PROP_ENABLED,
+  PROP_ACTIVE,
+  PROP_ROLE,
+  N_PROPS
+};
+
+static GParamSpec *gtk_action_helper_pspecs[N_PROPS];
+
+static void gtk_action_helper_observer_iface_init (GActionObserverInterface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (GtkActionHelper, gtk_action_helper, G_TYPE_OBJECT,
+  G_IMPLEMENT_INTERFACE (G_TYPE_ACTION_OBSERVER, gtk_action_helper_observer_iface_init))
+
+static void
+gtk_action_helper_report_change (GtkActionHelper *helper,
+                                 guint            prop_id)
+{
+  helper->reporting++;
+
+  if (!helper->application)
+    {
+      switch (prop_id)
+        {
+        case PROP_ENABLED:
+          gtk_widget_set_sensitive (GTK_WIDGET (helper->widget), helper->enabled);
+          break;
+
+        case PROP_ACTIVE:
+          {
+            GParamSpec *pspec;
+
+            pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (helper->widget), "active");
+
+            if (pspec && G_PARAM_SPEC_VALUE_TYPE (pspec) == G_TYPE_BOOLEAN)
+              g_object_set (G_OBJECT (helper->widget), "active", helper->active, NULL);
+          }
+          break;
+
+        case PROP_ROLE:
+          {
+            GParamSpec *pspec;
+
+            pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (helper->widget), "action-role");
+
+            if (pspec && G_PARAM_SPEC_VALUE_TYPE (pspec) == G_TYPE_UINT)
+              g_object_set (G_OBJECT (helper->widget), "action-role", helper->role, NULL);
+          }
+          break;
+
+        default:
+          g_assert_not_reached ();
+        }
+    }
+
+  g_object_notify_by_pspec (G_OBJECT (helper), gtk_action_helper_pspecs[prop_id]);
+  helper->reporting--;
+}
+
+static void
+gtk_action_helper_action_added (GtkActionHelper    *helper,
+                                gboolean            enabled,
+                                const GVariantType *parameter_type,
+                                GVariant           *state,
+                                gboolean            should_emit_signals)
+{
+  /* we can only activate if we have the correct type of parameter */
+  helper->can_activate = (helper->target == NULL && parameter_type == NULL) ||
+                          (helper->target != NULL && parameter_type != NULL &&
+                          g_variant_is_of_type (helper->target, parameter_type));
+
+  if (!helper->can_activate)
+    return;
+
+  helper->enabled = enabled;
+
+  if (helper->target != NULL && state != NULL)
+    {
+      helper->active = g_variant_equal (state, helper->target);
+      helper->role = GTK_ACTION_HELPER_ROLE_RADIO;
+    }
+
+  else if (state != NULL && g_variant_is_of_type (state, G_VARIANT_TYPE_BOOLEAN))
+    {
+      helper->active = g_variant_get_boolean (state);
+      helper->role = GTK_ACTION_HELPER_ROLE_TOGGLE;
+    }
+
+  if (should_emit_signals)
+    {
+      if (helper->enabled)
+        gtk_action_helper_report_change (helper, PROP_ENABLED);
+
+      if (helper->active)
+        gtk_action_helper_report_change (helper, PROP_ACTIVE);
+
+      if (helper->role)
+        gtk_action_helper_report_change (helper, PROP_ROLE);
+    }
+}
+
+static void
+gtk_action_helper_action_removed (GtkActionHelper *helper)
+{
+  if (!helper->can_activate)
+    return;
+
+  helper->can_activate = FALSE;
+
+  if (helper->enabled)
+    {
+      helper->enabled = FALSE;
+      gtk_action_helper_report_change (helper, PROP_ENABLED);
+    }
+
+  if (helper->active)
+    {
+      helper->enabled = FALSE;
+      gtk_action_helper_report_change (helper, PROP_ACTIVE);
+    }
+
+  if (helper->role)
+    {
+      helper->role = GTK_ACTION_HELPER_ROLE_NORMAL;
+      gtk_action_helper_report_change (helper, PROP_ROLE);
+    }
+}
+
+static void
+gtk_action_helper_action_enabled_changed (GtkActionHelper *helper,
+                                          gboolean         enabled)
+{
+  if (!helper->can_activate)
+    return;
+
+  if (helper->enabled == enabled)
+    return;
+
+  helper->enabled = enabled;
+  gtk_action_helper_report_change (helper, PROP_ENABLED);
+}
+
+static void
+gtk_action_helper_action_state_changed (GtkActionHelper *helper,
+                                        GVariant        *new_state)
+{
+  gboolean was_active;
+
+  if (!helper->can_activate)
+    return;
+
+  was_active = helper->active;
+
+  if (helper->target)
+    helper->active = g_variant_equal (new_state, helper->target);
+
+  else if (g_variant_is_of_type (new_state, G_VARIANT_TYPE_BOOLEAN))
+    helper->active = g_variant_get_boolean (new_state);
+
+  else
+    helper->active = FALSE;
+
+  if (helper->active != was_active)
+    gtk_action_helper_report_change (helper, PROP_ACTIVE);
+}
+
+static void
+gtk_action_helper_get_property (GObject *object, guint prop_id,
+                                GValue *value, GParamSpec *pspec)
+{
+  GtkActionHelper *helper = GTK_ACTION_HELPER (object);
+
+  switch (prop_id)
+    {
+    case PROP_ENABLED:
+      g_value_set_boolean (value, helper->enabled);
+      break;
+
+    case PROP_ACTIVE:
+      g_value_set_boolean (value, helper->active);
+      break;
+
+    case PROP_ROLE:
+      g_value_set_uint (value, helper->role);
+      break;
+
+    default:
+      g_assert_not_reached ();
+    }
+}
+
+static void
+gtk_action_helper_finalize (GObject *object)
+{
+  GtkActionHelper *helper = GTK_ACTION_HELPER (object);
+
+  if (helper->application)
+    {
+      g_signal_handlers_disconnect_by_data (helper->application, helper);
+      g_object_unref (helper->action_context);
+      g_object_unref (helper->application);
+
+      if (helper->widget)
+          g_object_unref (helper->widget);
+    }
+
+  g_free (helper->action_name);
+
+  if (helper->target)
+    g_variant_unref (helper->target);
+
+  G_OBJECT_CLASS (gtk_action_helper_parent_class)
+    ->finalize (object);
+}
+
+static void
+gtk_action_helper_observer_action_added (GActionObserver    *observer,
+                                         GActionObservable  *observable,
+                                         const gchar        *action_name,
+                                         const GVariantType *parameter_type,
+                                         gboolean            enabled,
+                                         GVariant           *state)
+{
+  gtk_action_helper_action_added (GTK_ACTION_HELPER (observer), enabled, parameter_type, state, TRUE);
+}
+
+static void
+gtk_action_helper_observer_action_enabled_changed (GActionObserver    *observer,
+                                                   GActionObservable  *observable,
+                                                   const gchar        *action_name,
+                                                   gboolean            enabled)
+{
+  gtk_action_helper_action_enabled_changed (GTK_ACTION_HELPER (observer), enabled);
+}
+
+static void
+gtk_action_helper_observer_action_state_changed (GActionObserver    *observer,
+                                                 GActionObservable  *observable,
+                                                 const gchar        *action_name,
+                                                 GVariant           *state)
+{
+  gtk_action_helper_action_state_changed (GTK_ACTION_HELPER (observer), state);
+}
+
+static void
+gtk_action_helper_observer_action_removed (GActionObserver    *observer,
+                                           GActionObservable  *observable,
+                                           const gchar        *action_name)
+{
+  gtk_action_helper_action_removed (GTK_ACTION_HELPER (observer));
+}
+
+static void
+gtk_action_helper_init (GtkActionHelper *helper)
+{
+}
+
+static void
+gtk_action_helper_class_init (GtkActionHelperClass *class)
+{
+  class->get_property = gtk_action_helper_get_property;
+  class->finalize = gtk_action_helper_finalize;
+
+  gtk_action_helper_pspecs[PROP_ENABLED] = g_param_spec_boolean ("enabled", "enabled", "enabled", FALSE,
+                                                                 G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
+  gtk_action_helper_pspecs[PROP_ACTIVE] = g_param_spec_boolean ("active", "active", "active", FALSE,
+                                                                G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
+  gtk_action_helper_pspecs[PROP_ROLE] = g_param_spec_uint ("role", "role", "role", 0, 2, 0,
+                                                           G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
+  g_object_class_install_properties (class, N_PROPS, gtk_action_helper_pspecs);
+}
+
+static void
+gtk_action_helper_observer_iface_init (GActionObserverInterface *iface)
+{
+  iface->action_added = gtk_action_helper_observer_action_added;
+  iface->action_enabled_changed = gtk_action_helper_observer_action_enabled_changed;
+  iface->action_state_changed = gtk_action_helper_observer_action_state_changed;
+  iface->action_removed = gtk_action_helper_observer_action_removed;
+}
+
+/*< private >
+ * gtk_action_helper_new:
+ * @widget: a #GtkWidget implementing #GtkActionable
+ *
+ * Creates a helper to track the state of a named action.  This will
+ * usually be used by widgets implementing #GtkActionable.
+ *
+ * This helper class is usually used by @widget itself.  In order to
+ * avoid reference cycles, the helper does not hold a reference on
+ * @widget, but will assume that it continues to exist for the duration
+ * of the life of the helper.  If you are using the helper from outside
+ * of the widget, you should take a ref on @widget for each ref you hold
+ * on the helper.
+ *
+ * Returns: a new #GtkActionHelper
+ */
+GtkActionHelper *
+gtk_action_helper_new (GtkActionable *widget)
+{
+  GtkActionHelper *helper;
+
+  g_return_val_if_fail (GTK_IS_ACTIONABLE (widget), NULL);
+  helper = g_object_new (GTK_TYPE_ACTION_HELPER, NULL);
+
+  helper->widget = GTK_WIDGET (widget);
+
+  if (helper->widget)
+    {
+      GParamSpec *pspec;
+
+      helper->enabled = gtk_widget_get_sensitive (GTK_WIDGET (helper->widget));
+
+      pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (helper->widget), "active");
+      if (pspec && G_PARAM_SPEC_VALUE_TYPE (pspec) == G_TYPE_BOOLEAN)
+        g_object_get (G_OBJECT (helper->widget), "active", &helper->active, NULL);
+    }
+
+  helper->action_context = _gtk_widget_get_action_muxer (GTK_WIDGET (widget));
+
+  return helper;
+}
+
+static void
+gtk_action_helper_active_window_changed (GObject    *object,
+                                         GParamSpec *pspec,
+                                         gpointer    user_data)
+{
+  GtkActionHelper *helper = user_data;
+  GActionMuxer *parent;
+
+  if (helper->widget)
+    g_object_unref (helper->widget);
+
+  helper->widget = GTK_WIDGET (gtk_application_get_active_window (helper->application));
+
+  if (helper->widget)
+    {
+      parent = g_object_ref (_gtk_widget_get_action_muxer (GTK_WIDGET (helper->widget)));
+      g_object_ref (helper->widget);
+    }
+  else
+    {
+      parent = g_action_muxer_new ();
+      g_action_muxer_insert (parent, "app", G_ACTION_GROUP (helper->application));
+    }
+
+  g_action_muxer_set_parent (helper->action_context, parent);
+  g_object_unref (parent);
+}
+
+GtkActionHelper *
+gtk_action_helper_new_with_application (GtkApplication *application)
+{
+  GtkActionHelper *helper;
+
+  g_return_val_if_fail (GTK_IS_APPLICATION (application), NULL);
+
+  helper = g_object_new (GTK_TYPE_ACTION_HELPER, NULL);
+  helper->application = g_object_ref (application);
+
+  helper->action_context = g_action_muxer_new ();
+  g_signal_connect (application, "notify::active-window", G_CALLBACK (gtk_action_helper_active_window_changed), helper);
+  gtk_action_helper_active_window_changed (NULL, NULL, helper);
+
+  return helper;
+}
+
+void
+gtk_action_helper_set_action_name (GtkActionHelper *helper,
+                                   const gchar     *action_name)
+{
+  gboolean was_enabled, was_active;
+  GtkActionHelperRole old_role;
+  const GVariantType *parameter_type;
+  gboolean enabled;
+  GVariant *state;
+
+  if (g_strcmp0 (action_name, helper->action_name) == 0)
+    return;
+
+  if (helper->action_name)
+    {
+      g_action_observable_unregister_observer (G_ACTION_OBSERVABLE (helper->action_context),
+                                               helper->action_name,
+                                               G_ACTION_OBSERVER (helper));
+      g_free (helper->action_name);
+    }
+
+  helper->action_name = g_strdup (action_name);
+
+  g_action_observable_register_observer (G_ACTION_OBSERVABLE (helper->action_context),
+                                         helper->action_name,
+                                         G_ACTION_OBSERVER (helper));
+
+  /* Start by recording the current state of our properties so we know
+   * what notify signals we will need to send.
+   */
+  was_enabled = helper->enabled;
+  was_active = helper->active;
+  old_role = helper->role;
+
+  if (g_action_group_query_action (G_ACTION_GROUP (helper->action_context), helper->action_name,
+                                   &enabled, &parameter_type, NULL, NULL, &state))
+    {
+      gtk_action_helper_action_added (helper, enabled, parameter_type, state, FALSE);
+
+      if (state)
+        g_variant_unref (state);
+    }
+  else
+    {
+      helper->enabled = FALSE;
+    }
+
+  /* Send the notifies for the properties that changed.
+   *
+   * When called during construction, widget is NULL.  We don't need to
+   * report in that case.
+   */
+  if (helper->enabled != was_enabled)
+    gtk_action_helper_report_change (helper, PROP_ENABLED);
+
+  if (helper->active != was_active)
+    gtk_action_helper_report_change (helper, PROP_ACTIVE);
+
+  if (helper->role != old_role)
+    gtk_action_helper_report_change (helper, PROP_ROLE);
+
+  if (!helper->application)
+    g_object_notify (G_OBJECT (helper->widget), "action-name");
+}
+
+/*< private >
+ * gtk_action_helper_set_action_target_value:
+ * @helper: a #GtkActionHelper
+ * @target_value: an action target, as per #GtkActionable
+ *
+ * This function consumes @action_target if it is floating.
+ */
+void
+gtk_action_helper_set_action_target_value (GtkActionHelper *helper,
+                                           GVariant        *target_value)
+{
+  gboolean was_enabled;
+  gboolean was_active;
+
+  if (target_value == helper->target)
+    return;
+
+  if (target_value && helper->target && g_variant_equal (target_value, helper->target))
+    return;
+
+  if (helper->target)
+    {
+      g_variant_unref (helper->target);
+      helper->target = NULL;
+    }
+
+  if (target_value)
+    helper->target = g_variant_ref_sink (target_value);
+
+  was_enabled = helper->enabled;
+  was_active = helper->active;
+
+  /* If we are attached to an action group then it is possible that this
+   * change of the target value could impact our properties (including
+   * changes to 'can_activate' and therefore 'enabled', due to resolving
+   * a parameter type mismatch).
+   *
+   * Start over again by pretending the action gets re-added.
+   */
+  helper->can_activate = FALSE;
+  helper->enabled = FALSE;
+  helper->active = FALSE;
+
+  if (helper->action_context)
+    {
+      const GVariantType *parameter_type;
+      gboolean enabled;
+      GVariant *state;
+
+      if (g_action_group_query_action (G_ACTION_GROUP (helper->action_context),
+                                       helper->action_name, &enabled, &parameter_type,
+                                       NULL, NULL, &state))
+        {
+          gtk_action_helper_action_added (helper, enabled, parameter_type, state, FALSE);
+
+          if (state)
+            g_variant_unref (state);
+        }
+    }
+
+  if (helper->enabled != was_enabled)
+    gtk_action_helper_report_change (helper, PROP_ENABLED);
+
+  if (helper->active != was_active)
+    gtk_action_helper_report_change (helper, PROP_ACTIVE);
+
+  if (!helper->application)
+    g_object_notify (G_OBJECT (helper->widget), "action-target");
+}
+
+const gchar *
+gtk_action_helper_get_action_name (GtkActionHelper *helper)
+{
+  if (helper == NULL)
+    return NULL;
+
+  return helper->action_name;
+}
+
+GVariant *
+gtk_action_helper_get_action_target_value (GtkActionHelper *helper)
+{
+  if (helper == NULL)
+    return NULL;
+
+  return helper->target;
+}
+
+GtkActionHelperRole
+gtk_action_helper_get_role (GtkActionHelper *helper)
+{
+  if (helper == NULL)
+    return GTK_ACTION_HELPER_ROLE_NORMAL;
+
+  return helper->role;
+}
+
+gboolean
+gtk_action_helper_get_enabled (GtkActionHelper *helper)
+{
+  g_return_val_if_fail (GTK_IS_ACTION_HELPER (helper), FALSE);
+
+  return helper->enabled;
+}
+
+gboolean
+gtk_action_helper_get_active (GtkActionHelper *helper)
+{
+  g_return_val_if_fail (GTK_IS_ACTION_HELPER (helper), FALSE);
+
+  return helper->active;
+}
+
+void
+gtk_action_helper_activate (GtkActionHelper *helper)
+{
+  g_return_if_fail (GTK_IS_ACTION_HELPER (helper));
+
+  if (!helper->can_activate || helper->reporting)
+    return;
+
+  g_action_group_activate_action (G_ACTION_GROUP (helper->action_context),
+                                  helper->action_name, helper->target);
+}