[gegl] panorama-projection: opt out of base-class multi-threading

[Øyvind Kolås <ok src gnome org>]

commit e751ab33b2d95c43c5b2e8482049b9ad09669520
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu May 3 12:11:54 2018 +0200

    panorama-projection: opt out of base-class multi-threading
    
    The base class duplicates the input buffers, which for a
    panorama is expensive.
    
    Even avoiding copies is not enough to make it fast, we
    need to make multiple samplers on the same buffer fast.

 operations/common/panorama-projection.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/panorama-projection.c b/operations/common/panorama-projection.c
index 08dd3d7..ef609c5 100644
--- a/operations/common/panorama-projection.c
+++ b/operations/common/panorama-projection.c
@@ -593,6 +593,9 @@ gegl_op_class_init (GeglOpClass *klass)
 
   filter_class->process = process;
   operation_class->prepare = prepare;
+  operation_class->threaded = FALSE; /* XXX: figure out a way to make
+multi-threaded access to cache-work, and add a flag to operation_class about
+not wanting duplicated inputs */
   operation_class->get_bounding_box = get_bounding_box;
   operation_class->get_required_for_output = get_required_for_output;