[gegl] GeglPath: document internal flattener function

[Ãyvind KolÃs <ok src gnome org>]

commit 0c8b8b2292d45a952f776becc6af0bff90f96b56
Author: Michael Murà <batolettre gmail com>
Date:   Thu Jun 30 13:37:35 2011 +0200

    GeglPath: document internal flattener function

 gegl/property-types/gegl-path.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/gegl/property-types/gegl-path.c b/gegl/property-types/gegl-path.c
index dfa9576..075552d 100644
--- a/gegl/property-types/gegl-path.c
+++ b/gegl/property-types/gegl-path.c
@@ -78,8 +78,20 @@ typedef struct InstructionInfo
   gint   n_items;
   gchar *name;
 
-  /* a flatten function pointer is kept for all stored InstructionInfo's but are only
+  /**
+   * flatten:
+   * @matrix: a #GeglMatrix3 transformation matrix
+   * @head: head of the new path
+   * @prev: current tail of the new path
+   * @self: the original node to convert
+   *
+   * a flatten function pointer is kept for all stored InstructionInfo's but are only
    * used for the internal ones
+   * This function is called for each node of the path to be flattened.
+   * This function should build a new flattened path on the fly.
+   * The first call to this function is made with @head and @prev = NULL
+   *
+   * Return a pointer to the head of the flattened path.
    */
   GeglPathList *(*flatten) (GeglMatrix3   *matrix,
                             GeglPathList *head,