[gegl/soc-2012-ops] add a revamped pixelize op to produce dot raster image

[Hans Shu Lo <hanslo src gnome org>]

commit 0669efb5dcc85f74091430ae442b24bb4bae770f
Author: Michael Murà <batolettre gmail com>
Date:   Mon Jun 4 14:40:10 2012 +0900

    add a revamped pixelize op to produce dot raster image

 operations/common/dot.c |  195 +++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 195 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/dot.c b/operations/common/dot.c
new file mode 100644
index 0000000..0d9df4d
--- /dev/null
+++ b/operations/common/dot.c
@@ -0,0 +1,195 @@
+/* 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 Ãyvind KolÃs <pippin gimp org>
+ * Copyright 2012 Michael Murà <batolettre gmail com>
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+#include <math.h>
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+gegl_chant_int_ui (size, _("Block Width"),  1, 123456, 16, 1, 1024, 1.5,
+   _("Size of each block in pixels"))
+gegl_chant_double(ratio, _("Dot size ratio"), 0.0, 1.0, 1.0,
+                  _("Size ratio of a dot inside each block"))
+
+#else
+
+#define GEGL_CHANT_TYPE_AREA_FILTER
+#define GEGL_CHANT_C_FILE       "dot.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  =
+  op_area->top    =
+  op_area->bottom = o->size;
+
+  gegl_operation_set_format (operation, "input",
+                             babl_format ("RGBA float"));
+  gegl_operation_set_format (operation, "output",
+                             babl_format ("RGBA float"));
+}
+
+static void
+calc_block_colors (gfloat* block_colors,
+                   const gfloat* input,
+                   const GeglRectangle* roi,
+                   gint size)
+{
+  gint cx0 = CELL_X(roi->x, size);
+  gint cy0 = CELL_Y(roi->y, size);
+  gint cx1 = CELL_X(roi->x + roi->width - 1, size);
+  gint cy1 = CELL_Y(roi->y + roi->height - 1, size);
+
+  gint cx;
+  gint cy;
+  gfloat weight = 1.0f / (size * size);
+  gint line_width = roi->width + 2*size;
+  /* loop over the blocks within the region of interest */
+  for (cy=cy0; cy<=cy1; ++cy)
+    {
+      for (cx=cx0; cx<=cx1; ++cx)
+        {
+          gint px = (cx * size) - roi->x + size;
+          gint py = (cy * size) - roi->y + size;
+
+          /* 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+size; ++j)
+            {
+              for (i=px; i<px+size; ++i)
+                {
+                  for (c=0; c<4; ++c)
+                    col[c] += input[(j*line_width + i)*4 + c];
+                }
+            }
+          for (c=0; c<4; ++c)
+            block_colors[c] = weight * col[c];
+          block_colors += 4;
+        }
+    }
+}
+
+static void
+dot (gfloat* buf,
+     const GeglRectangle* roi,
+     GeglChantO *o)
+{
+  gint cx0 = CELL_X(roi->x, o->size);
+  gint cy0 = CELL_Y(roi->y, o->size);
+  gint block_count_x = CELL_X(roi->x + roi->width - 1, o->size) - cx0 + 1;
+  gint block_count_y = CELL_Y(roi->y + roi->height - 1, o->size) - cy0 + 1;
+  gfloat* block_colors = g_new0 (gfloat, block_count_x * block_count_y * 4);
+  gint x;
+  gint y;
+  gint c;
+  gfloat radius2 = (o->size * o->ratio / 2.0);
+  radius2 *= radius2;
+
+/* calculate the average color of all the blocks */
+  calc_block_colors(block_colors, buf, roi, o->size);
+
+  /* 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, o->size) - cy0;
+      for (x=0; x<roi->width; ++x)
+        {
+          gint cx = CELL_X(x + roi->x, o->size) - cx0;
+          gfloat cellx = x + roi->x - (cx0 + cx) * o->size - o->size / 2.0;
+          gfloat celly = y + roi->y - (cy0 + cy) * o->size - o->size / 2.0;
+          
+          if (cellx * cellx + celly * celly > radius2)
+            for (c=0; c<4; ++c)
+              *buf++ = 0;
+          else
+            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,
+         gint                 level)
+{
+  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, &src_rect, 1.0, babl_format ("RGBA float"), buf, GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+  dot(buf, roi, o);
+  gegl_buffer_set (output, roi, 0, babl_format ("RGBA 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;
+
+  gegl_operation_class_set_keys (operation_class,
+    "categories" , "render",
+    "name"       , "gegl:dot",
+    "description",
+         _("Simplify image into an array of solid-colored dots"),
+    NULL);
+}
+
+#endif