[gegl] mirrors: pass-through on infinite planes (issue #179)

[Thomas Manni <tmanni src gnome org>]

commit 5bc4cced31c987ac27ade692f900152c95fcf73a
Author: Thomas Manni <thomas manni free fr>
Date:   Sun Aug 4 19:41:11 2019 +0200

    mirrors: pass-through on infinite planes (issue #179)

 operations/common/mirrors.c | 39 +++++++++++++++++++++++++++++++++++----
 1 file changed, 35 insertions(+), 4 deletions(-)
---
diff --git a/operations/common/mirrors.c b/operations/common/mirrors.c
index 85c26dce6..1c01dc002 100644
--- a/operations/common/mirrors.c
+++ b/operations/common/mirrors.c
@@ -358,7 +358,12 @@ get_required_for_output (GeglOperation       *operation,
                          const gchar         *input_pad,
                          const GeglRectangle *roi)
 {
-  GeglRectangle  result = get_effective_area (operation);
+  GeglRectangle result = *roi;
+  const GeglRectangle *in_rect =
+      gegl_operation_source_get_bounding_box (operation, "input");
+
+  if (in_rect && ! gegl_rectangle_is_infinite_plane (in_rect))
+    result = get_effective_area (operation);
 
   #ifdef TRACE
     g_warning ("> get_required_for_output src=%dx%d+%d+%d", result.width, result.height, result.x, result.y);
@@ -416,6 +421,31 @@ process (GeglOperation       *operation,
   return TRUE;
 }
 
+static gboolean
+operation_process (GeglOperation        *operation,
+                   GeglOperationContext *context,
+                   const gchar          *output_prop,
+                   const GeglRectangle  *result,
+                   gint                  level)
+{
+  GeglOperationClass  *operation_class;
+
+  const GeglRectangle *in_rect =
+    gegl_operation_source_get_bounding_box (operation, "input");
+
+  if (in_rect && gegl_rectangle_is_infinite_plane (in_rect))
+    {
+      gpointer in = gegl_operation_context_get_object (context, "input");
+      gegl_operation_context_take_object (context, "output",
+                                          g_object_ref (G_OBJECT (in)));
+      return TRUE;
+    }
+
+  operation_class = GEGL_OPERATION_CLASS (gegl_op_parent_class);
+
+  return operation_class->process (operation, context, output_prop, result,
+                                   gegl_operation_context_get_level (context));
+}
 
 static void
 gegl_op_class_init (GeglOpClass *klass)
@@ -426,9 +456,10 @@ gegl_op_class_init (GeglOpClass *klass)
   operation_class = GEGL_OPERATION_CLASS (klass);
   filter_class    = GEGL_OPERATION_FILTER_CLASS (klass);
 
-  filter_class->process = process;
-  operation_class->prepare = prepare;
-  operation_class->get_bounding_box = get_bounding_box;
+  filter_class->process                    = process;
+  operation_class->prepare                 = prepare;
+  operation_class->process                 = operation_process;
+  operation_class->get_bounding_box        = get_bounding_box;
   operation_class->get_required_for_output = get_required_for_output;
 
   gegl_operation_class_set_keys (operation_class,