[gegl] Added an implementation of posterize to workshop

[Øyvind Kolås <ok src gnome org>]

commit 163658082921e92828cd2f908fd38653c0a7417d
Author: �yvind Kolås <pippin gimp org>
Date:   Thu Nov 26 22:27:17 2009 +0000

    Added an implementation of posterize to workshop

 operations/workshop/posterize.c |   92 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 92 insertions(+), 0 deletions(-)
---
diff --git a/operations/workshop/posterize.c b/operations/workshop/posterize.c
new file mode 100644
index 0000000..43c515f
--- /dev/null
+++ b/operations/workshop/posterize.c
@@ -0,0 +1,92 @@
+/* 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 2009 �yvind Kolås <pippin gimp org>
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+gegl_chant_int (levels, _("Levels"), 1, 64, 8,
+                   _("number of levels per component"))
+
+#else
+
+#define GEGL_CHANT_TYPE_POINT_FILTER
+#define GEGL_CHANT_C_FILE       "posterize.c"
+#define GEGLV4
+
+#include "gegl-chant.h"
+
+#ifndef RINT
+#define RINT(a) ((gint)(a+0.5))
+#endif
+
+
+static void prepare (GeglOperation *operation)
+{
+  /* We posterize sRGB data since it is more perceptually spaced than linear data
+   */
+  gegl_operation_set_format (operation, "input", babl_format ("R'G'B'A float"));
+  gegl_operation_set_format (operation, "output", babl_format ("R'G'B'A float"));
+}
+
+static gboolean process (GeglOperation       *operation,
+                         void                *in_buf,
+                         void                *out_buf,
+                         glong                samples,
+                         const GeglRectangle *roi)
+{
+  GeglChantO *o      = GEGL_CHANT_PROPERTIES (operation);
+  gfloat     *src    = in_buf;
+  gfloat     *dest   = out_buf;
+  gfloat      levels = o->levels;
+
+  while (samples--)
+    {
+      gint i;
+      for (i=0; i < 3; i++)
+        dest[i] = RINT (src[i]   * levels) / levels;
+      dest[3] = src[3];
+
+      src  += 4;
+      dest += 4;
+    }
+
+  return TRUE;
+}
+
+static void
+gegl_chant_class_init (GeglChantClass *klass)
+{
+  GeglOperationClass            *operation_class;
+  GeglOperationPointFilterClass *point_filter_class;
+
+  operation_class    = GEGL_OPERATION_CLASS (klass);
+  point_filter_class = GEGL_OPERATION_POINT_FILTER_CLASS (klass);
+
+  point_filter_class->process = process;
+
+  operation_class->name        = "gegl:posterize";
+  operation_class->categories  = "color";
+  operation_class->description =
+     _("Reduces the number of levels in each color component of the image.");
+       
+}
+
+#endif