[gegl] gegl:mix add aa lerping in RGBA op

[Øyvind Kolås <ok src gnome org>]

commit 646c3993e12d501067b5a150992d303a804ce768
Author: Øyvind Kolås <pippin gimp org>
Date:   Fri Jun 23 13:53:49 2017 +0200

    gegl:mix add aa lerping in RGBA op

 operations/common/Makefile.am |    1 +
 operations/common/mix.c       |   97 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 98 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/Makefile.am b/operations/common/Makefile.am
index 5b0a655..292ff33 100644
--- a/operations/common/Makefile.am
+++ b/operations/common/Makefile.am
@@ -90,6 +90,7 @@ gegl_common_la_SOURCES =\
        maze.c \
        mblur.c \
        mirrors.c \
+       mix.c \
        mono-mixer.c \
        mosaic.c \
        motion-blur-circular.c \
diff --git a/operations/common/mix.c b/operations/common/mix.c
new file mode 100644
index 0000000..34169ea
--- /dev/null
+++ b/operations/common/mix.c
@@ -0,0 +1,97 @@
+/* This file is an image processing operation for GEGL
+ *
+ * GEGL is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * GEGL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with GEGL; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright 2017 Øyvind Kolås <pippin gimp org>
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+
+#ifdef GEGL_PROPERTIES
+
+property_double (ratio, _("Ratio"), 0.5)
+    description (_("mixing ratio, read as amount of aux, 0=input 0.5=half 1.0=aux"))
+
+#else
+
+#define GEGL_OP_POINT_COMPOSER
+#define GEGL_OP_NAME     mix
+#define GEGL_OP_C_SOURCE mix.c
+
+#include "gegl-op.h"
+
+static void prepare (GeglOperation *operation)
+{
+  const Babl *format;
+  format = babl_format ("RGBA float");
+  gegl_operation_set_format (operation, "input", format);
+  gegl_operation_set_format (operation, "aux", format);
+  gegl_operation_set_format (operation, "output", format);
+}
+
+static gboolean
+process (GeglOperation       *op,
+         void                *in_buf,
+         void                *aux_buf,
+         void                *out_buf,
+         glong                n_pixels,
+         const GeglRectangle *roi,
+         gint                 level)
+{
+  GeglProperties *o = GEGL_PROPERTIES (op);
+  gfloat * GEGL_ALIGNED in = in_buf;
+  gfloat * GEGL_ALIGNED aux = aux_buf;
+  gfloat * GEGL_ALIGNED out = out_buf;
+  gfloat r = o->ratio;
+  gfloat rr = 1.0 - o->ratio;
+
+  if (aux==NULL)
+    return TRUE;
+
+  while (n_pixels--)
+    {
+      out[0] = aux[0] * r + in[0] * rr;
+      out[1] = aux[1] * r + in[1] * rr;
+      out[2] = aux[2] * r + in[2] * rr;
+      out[3] = aux[3] * r + in[3] * rr;
+      in  += 4;
+      aux += 4;
+      out += 4;
+    }
+  return TRUE;
+}
+
+static void
+gegl_op_class_init (GeglOpClass *klass)
+{
+  GeglOperationClass              *operation_class;
+  GeglOperationPointComposerClass *point_composer_class;
+
+  operation_class      = GEGL_OPERATION_CLASS (klass);
+  point_composer_class = GEGL_OPERATION_POINT_COMPOSER_CLASS (klass);
+  operation_class->prepare = prepare;
+
+  point_composer_class->process    = process;
+
+  gegl_operation_class_set_keys (operation_class,
+    "name"       , "gegl:mix",
+    "title",       _("Mix"),
+    "description",
+          _("do a lerp, linear interpolation (lerp) between input and aux"),
+    NULL);
+}
+
+#endif