[gegl] GeglNode: added passthrough property

[Øyvind Kolås <ok src gnome org>]

commit 9c30bb4213d89413a65d11fc4ab39266e911da6a
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Jul 14 00:17:17 2014 +0200

    GeglNode: added passthrough property
    
    This boolean, which lives on the node; not the operation makes the contained
    op act like gegl:nop.

 gegl/gegl-xml.c                 |    8 ++++++++
 gegl/graph/gegl-node-private.h  |    2 ++
 gegl/graph/gegl-node.c          |   37 ++++++++++++++++++++++++++++++++++++-
 gegl/graph/gegl-node.h          |    6 ++++++
 gegl/operation/gegl-operation.c |   35 +++++++++++++++++++++++++++++++++--
 5 files changed, 85 insertions(+), 3 deletions(-)
---
diff --git a/gegl/gegl-xml.c b/gegl/gegl-xml.c
index 41ca7e4..96815cd 100644
--- a/gegl/gegl-xml.c
+++ b/gegl/gegl-xml.c
@@ -1073,6 +1073,10 @@ add_stack (SerializeState *ss,
                         xml_attr (ss->buf, "operation", class);
                         if (id != NULL)
                           xml_attr (ss->buf, "id", id);
+
+                        if (gegl_node_get_passthrough (iter) == TRUE)
+                          xml_attr (ss->buf, "passthrough", "true");
+
                         g_free (name);
                         g_free (class);
                       }
@@ -1103,6 +1107,10 @@ add_stack (SerializeState *ss,
                             xml_attr (ss->buf, "operation", class);
                             if (id != NULL)
                               xml_attr (ss->buf, "id", id);
+
+                            if (gegl_node_get_passthrough (iter) == TRUE)
+                              xml_attr (ss->buf, "passthrough", "true");
+
                             g_free (name);
                             g_free (class);
                           }
diff --git a/gegl/graph/gegl-node-private.h b/gegl/graph/gegl-node-private.h
index 222d141..f458176 100644
--- a/gegl/graph/gegl-node-private.h
+++ b/gegl/graph/gegl-node-private.h
@@ -79,6 +79,8 @@ struct _GeglNode
 
   GMutex          mutex;
 
+  gint            passthrough;
+
   /*< private >*/
   GeglNodePrivate *priv;
 };
diff --git a/gegl/graph/gegl-node.c b/gegl/graph/gegl-node.c
index 8fc8edc..4ab2103 100644
--- a/gegl/graph/gegl-node.c
+++ b/gegl/graph/gegl-node.c
@@ -50,7 +50,8 @@ enum
   PROP_OPERATION,
   PROP_NAME,
   PROP_DONT_CACHE,
-  PROP_USE_OPENCL
+  PROP_USE_OPENCL,
+  PROP_PASSTHROUGH
 };
 
 enum
@@ -172,6 +173,14 @@ gegl_node_class_init (GeglNodeClass *klass)
                                                         G_PARAM_CONSTRUCT |
                                                         G_PARAM_READWRITE));
 
+  g_object_class_install_property (gobject_class, PROP_PASSTHROUGH,
+                                   g_param_spec_boolean ("passthrough",
+                                                         "Passthrough",
+                                                        "Act as a nop, passing input unmodifed through to 
ouput.",
+                                                        FALSE,
+                                                        G_PARAM_CONSTRUCT |
+                                                        G_PARAM_READWRITE));
+
   gegl_node_signals[INVALIDATED] =
     g_signal_new ("invalidated",
                   G_TYPE_FROM_CLASS (klass),
@@ -305,6 +314,10 @@ gegl_node_local_set_property (GObject      *gobject,
         node->dont_cache = g_value_get_boolean (value);
         break;
 
+      case PROP_PASSTHROUGH:
+        node->passthrough = g_value_get_boolean (value);
+        break;
+
       case PROP_USE_OPENCL:
         node->use_opencl = g_value_get_boolean (value);
         break;
@@ -351,6 +364,10 @@ gegl_node_local_get_property (GObject    *gobject,
         g_value_set_boolean (value, node->dont_cache);
         break;
 
+      case PROP_PASSTHROUGH:
+        g_value_set_boolean (value, node->passthrough);
+        break;
+
       case PROP_USE_OPENCL:
         g_value_set_boolean (value, node->use_opencl);
         break;
@@ -2128,3 +2145,21 @@ gegl_node_new (void)
 {
   return g_object_new (GEGL_TYPE_NODE, NULL);
 }
+
+gboolean
+gegl_node_get_passthrough (GeglNode *node)
+{
+  g_return_val_if_fail (GEGL_IS_NODE (node), FALSE);
+
+  return node->passthrough;
+}
+
+void
+gegl_node_set_passthrough (GeglNode *node,
+                           gboolean  passthrough)
+{
+  g_return_if_fail (GEGL_IS_NODE (node));
+
+  gegl_node_invalidated (node, NULL, TRUE);
+  node->passthrough = passthrough;
+}
diff --git a/gegl/graph/gegl-node.h b/gegl/graph/gegl-node.h
index 5af5afe..df76656 100644
--- a/gegl/graph/gegl-node.h
+++ b/gegl/graph/gegl-node.h
@@ -667,6 +667,12 @@ GeglNode    * gegl_node_new_from_file    (const gchar   *path);
 gchar       * gegl_node_to_xml           (GeglNode      *node,
                                           const gchar   *path_root);
 
+gboolean       gegl_node_get_passthrough (GeglNode      *node);
+
+void           gegl_node_set_passthrough (GeglNode      *node,
+                                          gboolean       passthrough);
+
+
 G_END_DECLS
 
 #endif /* __GEGL_NODE_H__ */
diff --git a/gegl/operation/gegl-operation.c b/gegl/operation/gegl-operation.c
index add450a..4bcf029 100644
--- a/gegl/operation/gegl-operation.c
+++ b/gegl/operation/gegl-operation.c
@@ -14,7 +14,7 @@
  * License along with GEGL; if not, see <http://www.gnu.org/licenses/>.
  *
  * Copyright 2003      Calvin Williamson
- *           2005-2008 Øyvind Kolås
+ * 2005-2009,2011-2014 Øyvind Kolås
  */
 
 #include "config.h"
@@ -159,6 +159,13 @@ gegl_operation_process (GeglOperation        *operation,
       return TRUE;
     }
 
+  if (operation->node->passthrough)
+  {
+    GeglBuffer *input = GEGL_BUFFER (gegl_operation_context_get_object (context, "input"));
+    gegl_operation_context_take_object (context, output_pad, g_object_ref (G_OBJECT (input)));
+    return TRUE;
+  }
+
   g_return_val_if_fail (klass->process, FALSE);
 
   return klass->process (operation, context, output_pad, result, level);
@@ -173,7 +180,16 @@ gegl_operation_get_bounding_box (GeglOperation *self)
   GeglOperationClass *klass = GEGL_OPERATION_GET_CLASS (self);
   GeglRectangle       rect  = { 0, 0, 0, 0 };
 
-  if (klass->get_bounding_box)
+  if (self->node->passthrough)
+  {
+    GeglRectangle  result = { 0, 0, 0, 0 };
+    GeglRectangle *in_rect;
+    in_rect = gegl_operation_source_get_bounding_box (self, "input");
+    if (in_rect)
+      return *in_rect;
+    return result;
+  }
+  else if (klass->get_bounding_box)
     return klass->get_bounding_box (self);
 
   return rect;
@@ -191,6 +207,9 @@ gegl_operation_get_invalidated_by_change (GeglOperation       *self,
   g_return_val_if_fail (input_pad != NULL, retval);
   g_return_val_if_fail (input_region != NULL, retval);
 
+  if (self->node && self->node->passthrough)
+    return *input_region;
+
   klass = GEGL_OPERATION_GET_CLASS (self);
 
   if (input_region->width  == 0 ||
@@ -208,6 +227,9 @@ get_required_for_output (GeglOperation        *operation,
                          const gchar         *input_pad,
                          const GeglRectangle *roi)
 {
+  if (operation->node->passthrough)
+    return *roi;
+
   if (operation->node->is_graph)
     {
       return gegl_operation_get_required_for_output (operation, input_pad, roi);
@@ -227,6 +249,9 @@ gegl_operation_get_required_for_output (GeglOperation        *operation,
       roi->height == 0)
     return *roi;
 
+  if (operation->node->passthrough)
+    return *roi;
+
   g_assert (klass->get_required_for_output);
 
   return klass->get_required_for_output (operation, input_pad, roi);
@@ -240,6 +265,9 @@ gegl_operation_get_cached_region (GeglOperation        *operation,
 {
   GeglOperationClass *klass = GEGL_OPERATION_GET_CLASS (operation);
 
+  if (operation->node->passthrough)
+    return *roi;
+
   if (!klass->get_cached_region)
     {
       return *roi;
@@ -280,6 +308,9 @@ gegl_operation_prepare (GeglOperation *self)
 
   g_return_if_fail (GEGL_IS_OPERATION (self));
 
+  if (self->node->passthrough)
+    return;
+
   klass = GEGL_OPERATION_GET_CLASS (self);
 
   /* build OpenCL kernel */