[cogl] Add a version of _cogl_pipeline_get_layer which does not create it

[Neil Roberts <nroberts src gnome org>]

commit 740bd12f2ddd432af03e3ceb133db0d8e53cf716
Author: Neil Roberts <neil linux intel com>
Date:   Thu Feb 9 20:38:03 2012 +0000

    Add a version of _cogl_pipeline_get_layer which does not create it
    
    This adds _cogl_pipeline_get_layer_with_flags which takes a set of
    flags to modify the behaviour. The only flag currently available is
    one to disable creating the layer if the layer index does not already
    exist.
    
    Reviewed-by: Robert Bragg <robert linux intel com>

 cogl/cogl-pipeline-private.h |   13 +++++++++++--
 cogl/cogl-pipeline.c         |    7 ++++---
 2 files changed, 15 insertions(+), 5 deletions(-)
---
diff --git a/cogl/cogl-pipeline-private.h b/cogl/cogl-pipeline-private.h
index 5e4f0ff..072ab74 100644
--- a/cogl/cogl-pipeline-private.h
+++ b/cogl/cogl-pipeline-private.h
@@ -665,9 +665,18 @@ _cogl_pipeline_prune_redundant_ancestry (CoglPipeline *pipeline);
 void _cogl_pipeline_update_blend_enable (CoglPipeline *pipeline,
                                          CoglPipelineState changes);
 
+typedef enum
+{
+  COGL_PIPELINE_GET_LAYER_NO_CREATE
+} CoglPipelineGetLayerFlags;
+
 CoglPipelineLayer *
-_cogl_pipeline_get_layer (CoglPipeline *pipeline,
-                          int layer_index);
+_cogl_pipeline_get_layer_with_flags (CoglPipeline *pipeline,
+                                     int layer_index,
+                                     CoglPipelineGetLayerFlags flags);
+
+#define _cogl_pipeline_get_layer(p, l) \
+  _cogl_pipeline_get_layer_with_flags (p, l, 0)
 
 gboolean
 _cogl_is_pipeline_layer (void *object);
diff --git a/cogl/cogl-pipeline.c b/cogl/cogl-pipeline.c
index fa3b1e2..b94b16e 100644
--- a/cogl/cogl-pipeline.c
+++ b/cogl/cogl-pipeline.c
@@ -1707,8 +1707,9 @@ _cogl_pipeline_get_layer_info (CoglPipeline *pipeline,
 }
 
 CoglPipelineLayer *
-_cogl_pipeline_get_layer (CoglPipeline *pipeline,
-                          int layer_index)
+_cogl_pipeline_get_layer_with_flags (CoglPipeline *pipeline,
+                                     int layer_index,
+                                     CoglPipelineGetLayerFlags flags)
 {
   CoglPipeline *authority =
     _cogl_pipeline_get_authority (pipeline, COGL_PIPELINE_STATE_LAYERS);
@@ -1742,7 +1743,7 @@ _cogl_pipeline_get_layer (CoglPipeline *pipeline,
 
   _cogl_pipeline_get_layer_info (authority, &layer_info);
 
-  if (layer_info.layer)
+  if (layer_info.layer || (flags & COGL_PIPELINE_GET_LAYER_NO_CREATE))
     return layer_info.layer;
 
   ctx = _cogl_context_get_default ();