[gegl] added pixelise filter

[Øyvind Kolås <ok src gnome org>]

commit 59af83798fe9ca20a1efaccee7d6e66ec609426f
Author: Andy Gill <andyggill gmail com>
Date:   Wed Jan 26 13:22:17 2011 +0000

    added pixelise filter

 operations/common/pixelise.c              |  183 +++++++++++++++++++++++++++++
 tests/compositions/pixelise.xml           |   14 +++
 tests/compositions/reference/pixelise.png |  Bin 0 -> 5023 bytes
 3 files changed, 197 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/pixelise.c b/operations/common/pixelise.c
new file mode 100644
index 0000000..a87fbcb
--- /dev/null
+++ b/operations/common/pixelise.c
@@ -0,0 +1,183 @@
+/* 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 2006 �yvind Kolås <pippin gimp org>
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+#include <math.h>
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+gegl_chant_int (xsize, _("Block Width"), 1, 256, 8,
+   _("Width of blocks in pixels"))
+gegl_chant_int (ysize, _("Block Height"), 1, 256, 8,
+   _("Height of blocks in pixels"))
+
+#else
+
+#define GEGL_CHANT_TYPE_AREA_FILTER
+#define GEGL_CHANT_C_FILE       "pixelise.c"
+
+#include "gegl-chant.h"
+
+#define CELL_X(px, cell_width)  ((px) / (cell_width))
+#define CELL_Y(py, cell_height)  ((py) / (cell_height))
+
+
+static void prepare (GeglOperation *operation)
+{
+  GeglChantO              *o;
+  GeglOperationAreaFilter *op_area;
+
+  op_area = GEGL_OPERATION_AREA_FILTER (operation);
+  o       = GEGL_CHANT_PROPERTIES (operation);
+
+  op_area->left   =
+  op_area->right  = o->xsize;
+  op_area->top    =
+  op_area->bottom = o->ysize;
+
+  gegl_operation_set_format (operation, "output",
+                             babl_format ("RaGaBaA float"));
+}
+
+static void
+calc_block_colors (gfloat* block_colors,
+                   const gfloat* input,
+                   const GeglRectangle* roi,
+                   gint xsize,
+                   gint ysize)
+{
+  gint cx0 = CELL_X(roi->x, xsize);
+  gint cy0 = CELL_Y(roi->y, ysize);
+  gint cx1 = CELL_X(roi->x + roi->width - 1, xsize);
+  gint cy1 = CELL_Y(roi->y + roi->height - 1, ysize);
+  
+  gint cx;
+  gint cy;
+  gfloat weight = 1.0f / (xsize * ysize);
+  gint line_width = roi->width + 2*xsize;
+  /* loop over the blocks within the region of interest */
+  for (cy=cy0; cy<=cy1; ++cy)
+    {
+      for (cx=cx0; cx<=cx1; ++cx)
+        {
+          gint px = (cx * xsize) - roi->x + xsize;
+          gint py = (cy * ysize) - roi->y + ysize;
+          
+          /* calculate the average color for this block */
+          gint j,i,c;
+          gfloat col[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+          for (j=py; j<py+ysize; ++j)
+            {
+              for (i=px; i<px+xsize; ++i)
+                {
+                  for (c=0; c<4; ++c)
+                    col[c] += input[(py*line_width + px)*4 + c];
+                }
+            }
+          for (c=0; c<4; ++c)
+            block_colors[c] = weight * col[c];
+          block_colors += 4; 
+        }
+    }
+}
+
+static void 
+pixelise (gfloat* buf, 
+          const GeglRectangle* roi,
+          gint xsize, 
+          gint ysize)
+{
+  gint cx0 = CELL_X(roi->x, xsize);
+  gint cy0 = CELL_Y(roi->y, ysize);
+  gint block_count_x = CELL_X(roi->x + roi->width - 1, xsize) - cx0 + 1;
+  gint block_count_y = CELL_Y(roi->y + roi->height - 1, ysize) - cy0 + 1;
+  gfloat* block_colors = g_new0 (gfloat, block_count_x * block_count_y * 4);
+  gint x;
+  gint y;
+  gint c;
+
+  /* calculate the average color of all the blocks */
+  calc_block_colors(block_colors, buf, roi, xsize, ysize);
+
+  /* set each pixel to the average color of the block it belongs to */
+  for (y=0; y<roi->height; ++y)
+    {
+      gint cy = CELL_Y(y + roi->y, ysize) - cy0;
+      for (x=0; x<roi->width; ++x)
+        {
+          gint cx = CELL_X(x + roi->x, xsize) - cx0;
+          for (c=0; c<4; ++c)
+            *buf++ = block_colors[(cy*block_count_x + cx)*4 + c];
+        }
+    }
+
+  g_free (block_colors);
+}
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *output,
+         const GeglRectangle *roi)
+{
+  GeglRectangle src_rect;
+  GeglChantO *o = GEGL_CHANT_PROPERTIES (operation);
+  GeglOperationAreaFilter *op_area;
+  gfloat* buf;
+
+  op_area = GEGL_OPERATION_AREA_FILTER (operation);
+  src_rect = *roi;
+  src_rect.x -= op_area->left;
+  src_rect.y -= op_area->top;
+  src_rect.width += op_area->left + op_area->right;
+  src_rect.height += op_area->top + op_area->bottom;
+  
+  buf = g_new0 (gfloat, src_rect.width * src_rect.height * 4);
+
+  gegl_buffer_get (input, 1.0, &src_rect, babl_format ("RaGaBaA float"), buf, GEGL_AUTO_ROWSTRIDE);
+
+  pixelise(buf, roi, o->xsize, o->ysize);
+
+  gegl_buffer_set (output, roi, babl_format ("RaGaBaA float"), buf, GEGL_AUTO_ROWSTRIDE);
+  
+  g_free (buf);
+
+  return  TRUE;
+}
+
+
+static void
+gegl_chant_class_init (GeglChantClass *klass)
+{
+  GeglOperationClass       *operation_class;
+  GeglOperationFilterClass *filter_class;
+
+  operation_class = GEGL_OPERATION_CLASS (klass);
+  filter_class    = GEGL_OPERATION_FILTER_CLASS (klass);
+
+  filter_class->process    = process;
+  operation_class->prepare = prepare;
+
+  operation_class->categories  = "blur";
+  operation_class->name        = "gegl:pixelise";
+  operation_class->description =
+       _("Pixelise filter");
+}
+
+#endif
diff --git a/tests/compositions/pixelise.xml b/tests/compositions/pixelise.xml
new file mode 100644
index 0000000..363809a
--- /dev/null
+++ b/tests/compositions/pixelise.xml
@@ -0,0 +1,14 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<gegl>
+  <node operation='gegl:pixelise'>
+    <params>
+      <param name='xsize'>9</param>
+      <param name='ysize'>11</param>
+    </params>
+  </node>
+  <node operation='gegl:load'>
+    <params>
+      <param name='path'>data/parliament_0.jpg</param>
+    </params>
+  </node>
+</gegl>
diff --git a/tests/compositions/reference/pixelise.png b/tests/compositions/reference/pixelise.png
new file mode 100644
index 0000000..33a9302
Binary files /dev/null and b/tests/compositions/reference/pixelise.png differ