Removed special casing code in GtkCellLayout in favor of default implementation.

The fact that GtkCellLayout was checking "if (gtk_cell_layout_get_area (layout))"
and executing code contitionally from the apis instead of simply falling
back to the default implementation for these things was causing problems
in language bindings such as gtkmm... Regardless, the implementation
is cleaner this way too.

gtk/gtkcelllayout.c

@@ -97,12 +97,191 @@
 typedef GtkCellLayoutIface GtkCellLayoutInterface;
 G_DEFINE_INTERFACE (GtkCellLayout, gtk_cell_layout, G_TYPE_OBJECT);
 
+static void   gtk_cell_layout_default_pack_start         (GtkCellLayout         *cell_layout,
+							  GtkCellRenderer       *cell,
+							  gboolean               expand);
+static void   gtk_cell_layout_default_pack_end           (GtkCellLayout         *cell_layout,
+							  GtkCellRenderer       *cell,
+							  gboolean               expand);
+static void   gtk_cell_layout_default_clear              (GtkCellLayout         *cell_layout);
+static void   gtk_cell_layout_default_add_attribute      (GtkCellLayout         *cell_layout,
+							  GtkCellRenderer       *cell,
+							  const gchar           *attribute,
+							  gint                   column);
+static void   gtk_cell_layout_default_set_cell_data_func (GtkCellLayout         *cell_layout,
+							  GtkCellRenderer       *cell,
+							  GtkCellLayoutDataFunc  func,
+							  gpointer               func_data,
+							  GDestroyNotify         destroy);
+static void   gtk_cell_layout_default_clear_attributes   (GtkCellLayout         *cell_layout,
+							  GtkCellRenderer       *cell);
+static void   gtk_cell_layout_default_reorder            (GtkCellLayout         *cell_layout,
+							  GtkCellRenderer       *cell,
+							  gint                   position);
+static GList *gtk_cell_layout_default_get_cells          (GtkCellLayout         *cell_layout);
+
 
 static void
-gtk_cell_layout_default_init (GtkCellLayoutInterface *iface)
+gtk_cell_layout_default_init (GtkCellLayoutIface *iface)
 {
+  iface->pack_start         = gtk_cell_layout_default_pack_start;
+  iface->pack_end           = gtk_cell_layout_default_pack_end;
+  iface->clear              = gtk_cell_layout_default_clear;
+  iface->add_attribute      = gtk_cell_layout_default_add_attribute;
+  iface->set_cell_data_func = gtk_cell_layout_default_set_cell_data_func;
+  iface->clear_attributes   = gtk_cell_layout_default_clear_attributes;
+  iface->reorder            = gtk_cell_layout_default_reorder;
+  iface->get_cells          = gtk_cell_layout_default_get_cells;
 }
 
+
+/* Default implementation is to fall back on an underlying cell area */
+static void
+gtk_cell_layout_default_pack_start (GtkCellLayout         *cell_layout,
+				    GtkCellRenderer       *cell,
+				    gboolean               expand)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (area), cell, expand);
+    }
+}
+
+static void
+gtk_cell_layout_default_pack_end (GtkCellLayout         *cell_layout,
+				  GtkCellRenderer       *cell,
+				  gboolean               expand)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      gtk_cell_layout_pack_end (GTK_CELL_LAYOUT (area), cell, expand);
+    }
+}
+
+static void
+gtk_cell_layout_default_clear (GtkCellLayout *cell_layout)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      gtk_cell_layout_clear (GTK_CELL_LAYOUT (area));
+    }
+}
+
+static void
+gtk_cell_layout_default_add_attribute (GtkCellLayout         *cell_layout,
+				       GtkCellRenderer       *cell,
+				       const gchar           *attribute,
+				       gint                   column)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      gtk_cell_layout_add_attribute (GTK_CELL_LAYOUT (area), cell, attribute, column);
+    }
+}
+
+static void
+gtk_cell_layout_default_set_cell_data_func (GtkCellLayout         *cell_layout,
+					    GtkCellRenderer       *cell,
+					    GtkCellLayoutDataFunc  func,
+					    gpointer               func_data,
+					    GDestroyNotify         destroy)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      _gtk_cell_area_set_cell_data_func_with_proxy (area, cell, 
+						    (GFunc)func, func_data, destroy, 
+						    cell_layout);
+    }
+}
+
+static void
+gtk_cell_layout_default_clear_attributes (GtkCellLayout         *cell_layout,
+					  GtkCellRenderer       *cell)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      gtk_cell_layout_clear_attributes (GTK_CELL_LAYOUT (area), cell);
+    }
+}
+
+static void
+gtk_cell_layout_default_reorder (GtkCellLayout         *cell_layout,
+				 GtkCellRenderer       *cell,
+				 gint                   position)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      gtk_cell_layout_reorder (GTK_CELL_LAYOUT (area), cell, position);
+    }
+}
+
+static GList *
+gtk_cell_layout_default_get_cells (GtkCellLayout *cell_layout)
+{
+  GtkCellLayoutIface *iface;
+  GtkCellArea        *area;
+
+  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+
+  if (iface->get_area)
+    {
+      area = iface->get_area (cell_layout);
+
+      return gtk_cell_layout_get_cells (GTK_CELL_LAYOUT (area));
+    }
+  return NULL;
+}
+
+
 /**
  * gtk_cell_layout_pack_start:
  * @cell_layout: a #GtkCellLayout
@@ -122,23 +301,10 @@ gtk_cell_layout_pack_start (GtkCellLayout   *cell_layout,
                             GtkCellRenderer *cell,
                             gboolean         expand)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
   g_return_if_fail (GTK_IS_CELL_RENDERER (cell));
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->pack_start (cell_layout, cell, expand);
-
-  if (iface->pack_start)
-    iface->pack_start (cell_layout, cell, expand);
-  else
-    {
-      area = iface->get_area (cell_layout);
-
-      if (area)
-	gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (area), cell, expand);
-    }
 }
 
 /**
@@ -160,23 +326,10 @@ gtk_cell_layout_pack_end (GtkCellLayout   *cell_layout,
                           GtkCellRenderer *cell,
                           gboolean         expand)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
   g_return_if_fail (GTK_IS_CELL_RENDERER (cell));
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->pack_end (cell_layout, cell, expand);
-
-  if (iface->pack_end)
-    iface->pack_end (cell_layout, cell, expand);
-  else
-    {
-      area = iface->get_area (cell_layout);
-
-      if (area)
-	gtk_cell_layout_pack_end (GTK_CELL_LAYOUT (area), cell, expand);
-    }
 }
 
 /**
@@ -191,22 +344,9 @@ gtk_cell_layout_pack_end (GtkCellLayout   *cell_layout,
 void
 gtk_cell_layout_clear (GtkCellLayout *cell_layout)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->clear (cell_layout);
-
-  if (iface->clear)
-    iface->clear (cell_layout);
-  else
-    {
-      area = iface->get_area (cell_layout);
-
-      if (area)
-	gtk_cell_layout_clear (GTK_CELL_LAYOUT (area));
-    }
 }
 
 static void
@@ -216,28 +356,16 @@ gtk_cell_layout_set_attributesv (GtkCellLayout   *cell_layout,
 {
   gchar *attribute;
   gint column;
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
 
   attribute = va_arg (args, gchar *);
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  gtk_cell_layout_clear_attributes (cell_layout, cell);
-
-  if (iface->get_area)
-    area = iface->get_area (cell_layout);
-
-  if (iface->clear_attributes)
-    iface->clear_attributes (cell_layout, cell);
-  else if (area)
-    gtk_cell_layout_clear_attributes (GTK_CELL_LAYOUT (area), cell);
 
   while (attribute != NULL)
     {
       column = va_arg (args, gint);
-      if (iface->add_attribute)
+
-	iface->add_attribute (cell_layout, cell, attribute, column);
+      gtk_cell_layout_add_attribute (cell_layout, cell, attribute, column);
-      else if (area)
-	gtk_cell_layout_add_attribute (GTK_CELL_LAYOUT (area), cell, attribute, column);
 
       attribute = va_arg (args, gchar *);
     }
@@ -294,28 +422,12 @@ gtk_cell_layout_add_attribute (GtkCellLayout   *cell_layout,
                                const gchar     *attribute,
                                gint             column)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
   g_return_if_fail (GTK_IS_CELL_RENDERER (cell));
   g_return_if_fail (attribute != NULL);
   g_return_if_fail (column >= 0);
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->add_attribute (cell_layout, cell, attribute, column);
-
-  if (iface->add_attribute)
-    iface->add_attribute (cell_layout,
-			  cell,
-			  attribute,
-			  column);
-  else
-    {
-      area = iface->get_area (cell_layout);
-
-      if (area)
-	gtk_cell_layout_add_attribute (GTK_CELL_LAYOUT (area), cell, attribute, column);
-    }
 }
 
 /**
@@ -343,36 +455,11 @@ gtk_cell_layout_set_cell_data_func (GtkCellLayout         *cell_layout,
                                     gpointer               func_data,
                                     GDestroyNotify         destroy)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
   g_return_if_fail (GTK_IS_CELL_RENDERER (cell));
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE 
-
+    (cell_layout)->set_cell_data_func (cell_layout, cell, func, func_data, destroy);
-  if (iface->set_cell_data_func)
-    iface->set_cell_data_func (cell_layout,
-			       cell,
-			       func,
-			       func_data,
-			       destroy);
-  else
-    {
-      area = iface->get_area (cell_layout);
-
-      if (area)
-	{
-	  /* Ensure that the correct proxy object is sent to 'func' */
-	  if (GTK_CELL_LAYOUT (area) != cell_layout)
-	    _gtk_cell_area_set_cell_data_func_with_proxy (area, cell, 
-							  (GFunc)func, func_data, destroy, 
-							  cell_layout);
-	  else
-	    gtk_cell_layout_set_cell_data_func (GTK_CELL_LAYOUT (area), cell, 
-						func, func_data, destroy);
-	}
-    }
 }
 
 /**
@@ -389,23 +476,10 @@ void
 gtk_cell_layout_clear_attributes (GtkCellLayout   *cell_layout,
                                   GtkCellRenderer *cell)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
   g_return_if_fail (GTK_IS_CELL_RENDERER (cell));
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->clear_attributes (cell_layout, cell);
-
-  if (iface->clear_attributes)
-    iface->clear_attributes (cell_layout, cell);
-  else
-    {
-      area = iface->get_area (cell_layout);
-      
-      if (area)
-	gtk_cell_layout_clear_attributes (GTK_CELL_LAYOUT (area), cell);
-    }
 }
 
 /**
@@ -426,23 +500,10 @@ gtk_cell_layout_reorder (GtkCellLayout   *cell_layout,
                          GtkCellRenderer *cell,
                          gint             position)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_if_fail (GTK_IS_CELL_LAYOUT (cell_layout));
   g_return_if_fail (GTK_IS_CELL_RENDERER (cell));
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);
+  GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->reorder (cell_layout, cell, position);
-
-  if (iface->reorder)
-    iface->reorder (cell_layout, cell, position);
-  else
-    {
-      area = iface->get_area (cell_layout);
-      
-      if (area)
-	gtk_cell_layout_reorder (GTK_CELL_LAYOUT (area), cell, position);
-    }
 }
 
 /**
@@ -461,23 +522,9 @@ gtk_cell_layout_reorder (GtkCellLayout   *cell_layout,
 GList *
 gtk_cell_layout_get_cells (GtkCellLayout *cell_layout)
 {
-  GtkCellLayoutIface *iface;
-  GtkCellArea        *area;
-
   g_return_val_if_fail (GTK_IS_CELL_LAYOUT (cell_layout), NULL);
 
-  iface = GTK_CELL_LAYOUT_GET_IFACE (cell_layout);  
+  return GTK_CELL_LAYOUT_GET_IFACE (cell_layout)->get_cells (cell_layout);
-  if (iface->get_cells)
-    return iface->get_cells (cell_layout);
-  else
-    {
-      area = iface->get_area (cell_layout);
-      
-      if (area)
-	return gtk_cell_layout_get_cells (GTK_CELL_LAYOUT (area));
-    }
-
-  return NULL;
 }
 
 /**