[gimp] app: layer-modes: add comments to lighten/darken only

[Øyvind Kolås <ok src gnome org>]

commit acc58c421d9c4864ff21b3e88da475895bcd36db
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Feb 20 20:12:26 2017 +0100

    app: layer-modes: add comments to lighten/darken only
    
    The lack of a blend space is there for a reason, document it.

 app/operations/layer-modes/gimp-layer-modes.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/app/operations/layer-modes/gimp-layer-modes.c b/app/operations/layer-modes/gimp-layer-modes.c
index 1fbd3ee..adf73cc 100644
--- a/app/operations/layer-modes/gimp-layer-modes.c
+++ b/app/operations/layer-modes/gimp-layer-modes.c
@@ -557,8 +557,8 @@ static const GimpLayerModeInfo layer_mode_infos[] =
     .context              = GIMP_LAYER_MODE_CONTEXT_ALL,
     .paint_composite_mode = GIMP_LAYER_COMPOSITE_SRC_OVER,
     .composite_mode       = GIMP_LAYER_COMPOSITE_SRC_ATOP,
-    .composite_space      = GIMP_LAYER_COLOR_SPACE_RGB_LINEAR,
-    .blend_space          = GIMP_LAYER_COLOR_SPACE_RGB_LINEAR
+    .composite_space      = GIMP_LAYER_COLOR_SPACE_RGB_LINEAR
+    /* no blend_space: reuse composite space, no conversion thus fewer copies */
   },
 
   { GIMP_LAYER_MODE_LIGHTEN_ONLY,
@@ -569,8 +569,8 @@ static const GimpLayerModeInfo layer_mode_infos[] =
     .context              = GIMP_LAYER_MODE_CONTEXT_ALL,
     .paint_composite_mode = GIMP_LAYER_COMPOSITE_SRC_OVER,
     .composite_mode       = GIMP_LAYER_COMPOSITE_SRC_ATOP,
-    .composite_space      = GIMP_LAYER_COLOR_SPACE_RGB_LINEAR,
-    .blend_space          = GIMP_LAYER_COLOR_SPACE_RGB_LINEAR
+    .composite_space      = GIMP_LAYER_COLOR_SPACE_RGB_LINEAR
+    /* no blend_space: reuse composite space, no conversion thus fewer copies */
   },
 
   { GIMP_LAYER_MODE_HSV_HUE,