[gegl/soc-2012-ops] Shift operation

[Hans Shu Lo <hanslo src gnome org>]

commit 635bae8d2f4dd2e1845eac6bafbd78e64143fec9
Author: Hans Lo <hansshulo gmail com>
Date:   Tue May 22 14:17:48 2012 -0400

    Shift operation
    
    Shifts each row or column of pixels by a random amount.

 operations/common/shift.c |  187 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 187 insertions(+), 0 deletions(-)
---
diff --git a/operations/common/shift.c b/operations/common/shift.c
new file mode 100644
index 0000000..844c268
--- /dev/null
+++ b/operations/common/shift.c
@@ -0,0 +1,187 @@
+/* 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 1997 Brian Degenhardt <bdegenha ucsd edu>
+ * Copyright 1997 Federico Mena Quinter <quartic polloux fciencias unam mx>
+ * Copyright 2012 Hans Lo <hansshulo gmail com>
+ */
+
+#include "config.h"
+#include <glib/gi18n-lib.h>
+
+#ifdef GEGL_CHANT_PROPERTIES
+
+gegl_chant_int (shift, _("Shift"), 1, 200, 5,
+                   _("Maximum amount to shift"))
+
+gegl_chant_int (seed, _("Seed"), 0, 100, 0,
+                   _("Random seed"))
+
+gegl_chant_register_enum (gegl_direction)
+  enum_value (GEGL_HORIZONTAL, "Horizontal")
+  enum_value (GEGL_VERTICAL, "Vertical")
+gegl_chant_register_enum_end (GeglDirection)
+
+
+gegl_chant_enum (direction, _("Direction"), GeglDirection, gegl_direction,
+                 GEGL_HORIZONTAL, _("Shift direction"))
+
+#else
+
+#define GEGL_CHANT_TYPE_AREA_FILTER
+#define GEGL_CHANT_C_FILE       "shift.c"
+
+#include "gegl-chant.h"
+#include <stdio.h>
+#include <math.h>
+#include <stdlib.h>
+
+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   = o->shift;
+  op_area->right  = o->shift;
+  op_area->top    = o->shift;
+  op_area->bottom = o->shift;
+
+  gegl_operation_set_format (operation, "input",
+                             babl_format ("RGBA float"));
+  gegl_operation_set_format (operation, "output",
+                             babl_format ("RGBA float"));
+}
+
+static gboolean
+process (GeglOperation       *operation,
+         GeglBuffer          *input,
+         GeglBuffer          *output,
+         const GeglRectangle *result,
+         gint                 level)
+{
+  GeglOperationAreaFilter *op_area = GEGL_OPERATION_AREA_FILTER (operation);
+  GeglChantO *o                    = GEGL_CHANT_PROPERTIES (operation);
+  GeglRectangle src_rect;
+
+  gfloat *src_buf;
+  gfloat *dst_buf;
+
+  gint x = 0; /* initial x                   */
+  gint y = 0; /*           and y coordinates */
+    
+  gfloat *in_pixel;
+  gfloat *out_pixel;
+
+  gint n_pixels = result->width * result->height;
+  gint i;
+
+  GRand *gr;
+  gint shift; /* random shift amount */
+  gint s = o->shift; /* max shift amount */
+
+  src_rect.x      = result->x - op_area->left;
+  src_rect.width  = result->width + op_area->left + op_area->right;
+  src_rect.y      = result->y - op_area->top;
+  src_rect.height = result->height + op_area->top + op_area->bottom;
+
+  src_buf = g_slice_alloc (src_rect.width * src_rect.height * 4 * sizeof(gfloat));
+  dst_buf = g_slice_alloc (result->width * result->height * 4 * sizeof(gfloat));
+
+  in_pixel = src_buf;
+  out_pixel = dst_buf;
+
+  gegl_buffer_get (input, &src_rect, 1.0, babl_format ("RGBA float"),
+		   src_buf, GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+  gr = g_rand_new ();
+  g_rand_set_seed (gr, o->seed);
+  shift = g_rand_int_range(gr, -s, s);
+  
+  while (n_pixels--)
+    {
+      /* select the desired input pixel */
+      if (o->direction == GEGL_HORIZONTAL)
+	{
+	  in_pixel = src_buf + 4*(src_rect.width * (s + y) + s + x + shift);
+	}
+      else if (o->direction == GEGL_VERTICAL)
+	{
+	  in_pixel = src_buf + 4*(src_rect.width * (s + y + shift) + s + x);
+	  out_pixel = dst_buf + 4*(result->width * y + x);
+	}
+      
+      /* copy pixel */
+      for (i = 0; i < 4; i++)
+	{
+	  *out_pixel = *in_pixel;
+	  in_pixel ++;
+	  out_pixel ++;
+	}
+      
+      /* update x and y coordinates and shift amount if necessary */
+      if (o->direction == GEGL_HORIZONTAL)
+	{
+	  x++;
+	  if (x == result->width)
+	    {
+	      x = 0;
+	      y++;
+	      shift = g_rand_int_range(gr, -s, s);
+	    }
+	}
+      else if (o->direction == GEGL_VERTICAL)
+	{
+	  y++;
+	  if (y == result->height)
+	    {
+	      y = 0;
+	      x++;
+	      shift = g_rand_int_range(gr, -s, s);
+	    }
+	}
+    }
+  
+  g_rand_free (gr);
+
+  gegl_buffer_set (output, result, 0, babl_format ("RGBA float"), dst_buf, GEGL_AUTO_ROWSTRIDE);
+  g_slice_free1 (src_rect.width * src_rect.height * 4 * sizeof(gfloat), src_buf);
+  g_slice_free1 (result->width * result->height * 4 * sizeof(gfloat), dst_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" , "distort",
+    "name"       , "gegl:shift",
+    "description", _("Shift by a random number of pixels"),
+    NULL);
+}
+
+#endif