[nautilus] background: make NautilusDesktopBackground a singleton

[Cosimo Cecchi <cosimoc src gnome org>]

commit 843e6a9b9331a3e7a318df03b4074deb1163e386
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Sun Oct 10 02:56:09 2010 +0200

    background: make NautilusDesktopBackground a singleton
    
    This avoids the need of using g_object_set_data() hacks to get the
    background from the desktop icon container.

 libnautilus-private/nautilus-desktop-background.c |   36 ++++++++++++++-------
 libnautilus-private/nautilus-desktop-background.h |    4 +--
 2 files changed, 25 insertions(+), 15 deletions(-)
---
diff --git a/libnautilus-private/nautilus-desktop-background.c b/libnautilus-private/nautilus-desktop-background.c
index b501cb3..d737f59 100644
--- a/libnautilus-private/nautilus-desktop-background.c
+++ b/libnautilus-private/nautilus-desktop-background.c
@@ -45,6 +45,8 @@ static void init_fade (NautilusDesktopBackground *self);
 static void free_fade (NautilusDesktopBackground *self);
 static void queue_background_change (NautilusDesktopBackground *self);
 
+static NautilusDesktopBackground *singleton = NULL;
+
 G_DEFINE_TYPE (NautilusDesktopBackground, nautilus_desktop_background, G_TYPE_OBJECT);
 
 enum {
@@ -481,11 +483,6 @@ nautilus_desktop_background_constructed (GObject *obj)
 
         g_assert (widget != NULL);
 
-        /* FIXME: this is ugly, but it's the only way of handling background DnD on
-         * the desktop without refactoring half nautilus.
-         */
-        g_object_set_data (G_OBJECT (widget), "desktop-background", self);
-
  	g_signal_connect_object (widget, "destroy",
                                  G_CALLBACK (on_widget_destroyed), self, 0);
 	g_signal_connect_object (widget, "realize",
@@ -519,6 +516,26 @@ nautilus_desktop_background_set_property (GObject *object,
         }
 }
 
+static GObject *
+nautilus_desktop_background_constructor (GType type,
+                                         guint n_construct_params,
+                                         GObjectConstructParam *construct_params)
+{
+        GObject *retval;
+
+        if (singleton != NULL) {
+                return g_object_ref (singleton);
+        }
+
+        retval = G_OBJECT_CLASS (nautilus_desktop_background_parent_class)->constructor
+                (type, n_construct_params, construct_params);
+
+        singleton = NAUTILUS_DESKTOP_BACKGROUND (retval);
+        g_object_add_weak_pointer (retval, (gpointer) &singleton);
+
+        return retval;
+}
+
 static void
 nautilus_desktop_background_class_init (NautilusDesktopBackgroundClass *klass)
 {
@@ -528,6 +545,7 @@ nautilus_desktop_background_class_init (NautilusDesktopBackgroundClass *klass)
 	object_class = G_OBJECT_CLASS (klass);
 	object_class->finalize = nautilus_desktop_background_finalize;
         object_class->set_property = nautilus_desktop_background_set_property;
+        object_class->constructor = nautilus_desktop_background_constructor;
         object_class->constructed = nautilus_desktop_background_constructed;
 
         pspec = g_param_spec_object ("widget", "The widget for this background",
@@ -559,15 +577,9 @@ nautilus_desktop_background_init (NautilusDesktopBackground *self)
 }
 
 void
-nautilus_desktop_background_receive_dropped_background_image (NautilusIconContainer *container,
+nautilus_desktop_background_receive_dropped_background_image (NautilusDesktopBackground *self,
                                                               const char *image_uri)
 {
-        NautilusDesktopBackground *self;
-
-        self = g_object_get_data (G_OBJECT (container), "desktop-background");
-
-        g_assert (self != NULL);
-
 	/* Currently, we only support tiled images. So we set the placement.
 	 */
 	gnome_bg_set_placement (self->details->bg,
diff --git a/libnautilus-private/nautilus-desktop-background.h b/libnautilus-private/nautilus-desktop-background.h
index 1ef2dc0..69fd35c 100644
--- a/libnautilus-private/nautilus-desktop-background.h
+++ b/libnautilus-private/nautilus-desktop-background.h
@@ -31,8 +31,6 @@
 
 #include <gtk/gtk.h>
 
-#include "nautilus-icon-container.h"
-
 typedef struct NautilusDesktopBackground NautilusDesktopBackground;
 typedef struct NautilusDesktopBackgroundClass NautilusDesktopBackgroundClass;
 
@@ -51,7 +49,7 @@ typedef struct NautilusDesktopBackgroundClass NautilusDesktopBackgroundClass;
 GType nautilus_desktop_background_get_type (void);
 NautilusDesktopBackground * nautilus_desktop_background_new (GtkWidget *widget);
 
-void nautilus_desktop_background_receive_dropped_background_image (NautilusIconContainer *container,
+void nautilus_desktop_background_receive_dropped_background_image (NautilusDesktopBackground *self,
 								   const gchar *image_uri);
 
 typedef struct NautilusDesktopBackgroundDetails NautilusDesktopBackgroundDetails;