[gegl] add a map_relative operator

[Øyvind Kolås <ok src gnome org>]

commit e405366072542781b04664497c1377ba15137de2
Author: Michael Muré <batolettre gmail com>
Date:   Wed May 25 21:45:46 2011 +0200

    add a map_relative operator

 operations/common/map_relative.c |  164 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 164 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/map_relative.c b/operations/common/map_relative.c
new file mode 100644
index 0000000..b9c03f0
--- /dev/null
+++ b/operations/common/map_relative.c
@@ -0,0 +1,164 @@
+/* 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 2011 Michael Muré <batolettre gmail com>
+ *
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+#include <gegl.h>
+#include <gegl-plugin.h>
+#include <gegl-utils.h>
+#include "buffer/gegl-sampler.h"
+#include "buffer/gegl-buffer-iterator.h"
+
+#include <stdio.h>
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+#else
+
+#define GEGL_CHANT_TYPE_COMPOSER
+#define GEGL_CHANT_C_FILE       "map_relative.c"
+
+#include "gegl-chant.h"
+
+
+static void
+prepare (GeglOperation *operation)
+{
+  Babl *format = babl_format ("RGBA float");
+
+  gegl_operation_set_format (operation, "input", format);
+  gegl_operation_set_format (operation, "aux", babl_format_n (babl_type ("float"), 2));
+  gegl_operation_set_format (operation, "output", format);
+}
+
+static GeglRectangle
+get_required_for_output (GeglOperation       *operation,
+                         const gchar         *input_pad,
+                         const GeglRectangle *region)
+{
+  GeglRectangle result = *gegl_operation_source_get_bounding_box (operation, "input");
+
+  return result;
+}
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *aux,
+         GeglBuffer          *output,
+         const GeglRectangle *result)
+{
+  Babl                 *format_io, *format_coords;
+  GeglSampler          *sampler;
+  GType                 desired_type;
+  GeglInterpolation     interpolation;
+  GeglBufferIterator   *it;
+  gint                  index_in, index_out, index_coords;
+
+  format_io = babl_format ("RGBA float");
+  format_coords = babl_format_n (babl_type ("float"), 2);
+
+  interpolation = gegl_buffer_interpolation_from_string ("cubic");
+  desired_type = gegl_sampler_type_from_interpolation (interpolation);
+
+  sampler = g_object_new (desired_type,
+                          "format", format_io,
+                          "buffer", input,
+                          NULL);
+
+  gegl_sampler_prepare (sampler);
+
+  if (aux != NULL)
+    {
+      it = gegl_buffer_iterator_new (output, result, format_io, GEGL_BUFFER_WRITE);
+      index_out = 0;
+
+      index_coords = gegl_buffer_iterator_add (it, aux, result, format_coords, GEGL_BUFFER_READ);
+      index_in = gegl_buffer_iterator_add (it, input, result, format_io, GEGL_BUFFER_READ);
+
+      while (gegl_buffer_iterator_next (it))
+        {
+          gint        i;
+          gint        n_pixels = it->length;
+          gint        x = it->roi->x; /* initial x                   */
+          gint        y = it->roi->y; /*           and y coordinates */
+          gfloat     *in = it->data[index_in];
+          gfloat     *out = it->data[index_out];
+          gfloat     *coords = it->data[index_coords];
+
+          for (i=0; i<n_pixels; i++)
+            {
+              /* if the coordinate asked is an exact pixel, we fetch it directly, to avoid the blur of sampling */
+              if (coords[0] == 0 && coords[1] == 0)
+                {
+                  out[0] = in[0];
+                  out[1] = in[1];
+                  out[2] = in[2];
+                  out[3] = in[3];
+                }
+              else
+                {
+                  gegl_sampler_get (sampler, x+coords[0], y+coords[1], out);
+                }
+
+              coords += 2;
+              in += 4;
+              out += 4;
+
+              /* update x and y coordinates */
+              x++;
+              if (x >= (it->roi->x + it->roi->width))
+                {
+                  x = it->roi->x;
+                  y++;
+                }
+
+            }
+        }
+    }
+  else
+    {
+      gegl_buffer_copy (input, result, output, result);
+    }
+
+  g_object_unref (sampler);
+
+  return TRUE;
+}
+
+static void
+gegl_chant_class_init (GeglChantClass *klass)
+{
+  GeglOperationClass         *operation_class;
+  GeglOperationComposerClass *composer_class;
+
+  operation_class = GEGL_OPERATION_CLASS (klass);
+  composer_class  = GEGL_OPERATION_COMPOSER_CLASS (klass);
+
+  composer_class->process = process;
+  operation_class->prepare = prepare;
+  operation_class->get_required_for_output = get_required_for_output;
+
+  operation_class->name        = "gegl:map-relative";
+
+  operation_class->categories  = "transform";
+  operation_class->description = _("sample input with an auxiliary buffer that contain relative source coordinates");
+}
+#endif