[gimp/goat-invasion: 504/526] app: added gegl version of lighten only blending mode

[Michael Natterer <mitch src gnome org>]

commit 08805a5593523ed47f4e794652a1f6d1d694685b
Author: Ville Sokk <ville sokk gmail com>
Date:   Tue Apr 17 23:00:28 2012 +0300

    app: added gegl version of lighten only blending mode

 app/gegl/gimp-gegl-nodes.c              |    3 +--
 app/gegl/gimpoperationlightenonlymode.c |   29 ++++++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 7 deletions(-)
---
diff --git a/app/gegl/gimp-gegl-nodes.c b/app/gegl/gimp-gegl-nodes.c
index 1b05df5..2038488 100644
--- a/app/gegl/gimp-gegl-nodes.c
+++ b/app/gegl/gimp-gegl-nodes.c
@@ -257,7 +257,6 @@ gimp_gegl_node_set_layer_mode (GeglNode             *node,
     case GIMP_ADDITION_MODE:
     case GIMP_SUBTRACT_MODE:
     case GIMP_DARKEN_ONLY_MODE:
-    case GIMP_LIGHTEN_ONLY_MODE:
     case GIMP_HUE_MODE:
     case GIMP_SATURATION_MODE:
     case GIMP_COLOR_MODE:
@@ -296,7 +295,7 @@ gimp_gegl_node_set_layer_mode (GeglNode             *node,
     case GIMP_ADDITION_MODE:      operation = "gimp:addition-mode"; break;
     case GIMP_SUBTRACT_MODE:      operation = "gimp:subtract-mode"; break;
     case GIMP_DARKEN_ONLY_MODE:   operation = "gimp:darken-mode"; break;
-    case GIMP_LIGHTEN_ONLY_MODE:  operation = "gimp:lighten-mode"; break;
+    case GIMP_LIGHTEN_ONLY_MODE:  operation = "gimp:lighten-only-mode"; break;
     case GIMP_HUE_MODE:           operation = "gimp:hue-mode"; break;
     case GIMP_SATURATION_MODE:    operation = "gimp:saturation-mode"; break;
     case GIMP_COLOR_MODE:         operation = "gimp:color-mode"; break;
diff --git a/app/gegl/gimpoperationlightenonlymode.c b/app/gegl/gimpoperationlightenonlymode.c
index 5915799..96c5013 100644
--- a/app/gegl/gimpoperationlightenonlymode.c
+++ b/app/gegl/gimpoperationlightenonlymode.c
@@ -3,6 +3,7 @@
  *
  * gimpoperationlightenonlymode.c
  * Copyright (C) 2008 Michael Natterer <mitch gimp org>
+ *               2012 Ville Sokk <ville sokk gmail com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -40,6 +41,14 @@ static gboolean gimp_operation_lighten_only_mode_process (GeglOperation       *o
 G_DEFINE_TYPE (GimpOperationLightenOnlyMode, gimp_operation_lighten_only_mode,
                GIMP_TYPE_OPERATION_POINT_LAYER_MODE)
 
+static void prepare (GeglOperation *operation)
+{
+  const Babl *format = babl_format ("R'G'B'A float");
+
+  gegl_operation_set_format (operation, "input",  format);
+  gegl_operation_set_format (operation, "aux",    format);
+  gegl_operation_set_format (operation, "output", format);
+}
 
 static void
 gimp_operation_lighten_only_mode_class_init (GimpOperationLightenOnlyModeClass *klass)
@@ -55,7 +64,8 @@ gimp_operation_lighten_only_mode_class_init (GimpOperationLightenOnlyModeClass *
            "description", "GIMP lighten only mode operation",
            NULL);
 
-  point_class->process         = gimp_operation_lighten_only_mode_process;
+  point_class->process     = gimp_operation_lighten_only_mode_process;
+  operation_class->prepare = prepare;
 }
 
 static void
@@ -69,7 +79,7 @@ gimp_operation_lighten_only_mode_process (GeglOperation       *operation,
                                           void                *aux_buf,
                                           void                *out_buf,
                                           glong                samples,
-                                          const GeglRectangle *roi,
+                                          const GeglRectangle *result,
                                           gint                 level)
 {
   gfloat *in    = in_buf;
@@ -78,11 +88,20 @@ gimp_operation_lighten_only_mode_process (GeglOperation       *operation,
 
   while (samples--)
     {
-      out[RED]   = in[RED];
-      out[GREEN] = in[GREEN];
-      out[BLUE]  = in[BLUE];
+      gint b;
+      gfloat comp_alpha = MIN (in[ALPHA] * layer[ALPHA], layer[ALPHA] * in[ALPHA]);
+      gfloat new_alpha  = in[ALPHA] + (1 - in[ALPHA]) * comp_alpha;
+      gfloat ratio      = comp_alpha / new_alpha;
+
       out[ALPHA] = in[ALPHA];
 
+      for (b = RED; b < ALPHA; b++)
+        {
+          gfloat comp = MAX (layer[b], in[b]);
+
+          out[b] = comp * ratio + in[b] * (1 - ratio);
+        }
+
       in    += 4;
       layer += 4;
       out   += 4;