[Gegl-developer] Operations that I require

[Mark Probst]

Ok, so here's my mono mixer, implemented as a generic filter.

Next stop: gradient curves.  That'll be a bit more complex...

/* 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 2 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, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 * Copyright 2006 Mark Probst <mark.probst at gmail.com>
 */

#if GEGL_CHANT_PROPERTIES

  gegl_chant_double (red, -10.0, 10.0, 0.5, "Amount of red")
  gegl_chant_double (green, -10.0, 10.0, 0.25, "Amount of green")
  gegl_chant_double (blue, -10.0, 10.0, 0.25, "Amount of blue")

#else

#define GEGL_CHANT_FILTER

#define GEGL_CHANT_NAME         mono_mixer
#define GEGL_CHANT_SELF         "mono-mixer.c"

#define GEGL_CHANT_DESCRIPTION  "Monochrome channel mixer"

#define GEGL_CHANT_CATEGORIES   "color"

#include "gegl-chant.h"

static gboolean
process (GeglOperation *operation,
	 gpointer       context_id)
{
  GeglChantOperation *self;
  GeglBuffer         *input;
  GeglBuffer	     *output;
  gfloat             *in_buf;
  gfloat             *out_buf;
  GeglRectangle      *result_rect = gegl_operation_result_rect
(operation, context_id);
  gfloat              red, green, blue;

  self = GEGL_CHANT_OPERATION (operation);
  input = GEGL_BUFFER (gegl_operation_get_data (operation, context_id,
"input"));

  red = self->red;
  green = self->green;
  blue = self->blue;

  output = g_object_new (GEGL_TYPE_BUFFER,
			 "format", babl_format ("YA float"),
			 "x", result_rect->x,
			 "y", result_rect->y,
			 "width", result_rect->width,
			 "height", result_rect->height,
			 NULL);

  if ((result_rect->width > 0) && (result_rect->height > 0))
  {
      gint num_pixels = gegl_buffer_pixels (input);
      gint i;
      gfloat *in_pixel, *out_pixel;

      in_buf = g_malloc (4 * sizeof (gfloat) * num_pixels);
      out_buf = g_malloc (2 * sizeof(gfloat) * num_pixels);

      gegl_buffer_get (input, result_rect, 1.0, babl_format ("RGBA
float"), in_buf);

      in_pixel = in_buf;
      out_pixel = out_buf;
      for (i = 0; i < num_pixels; ++i)
      {
	  out_pixel[0] = in_pixel[0] * red + in_pixel[1] * green + in_pixel[2] * blue;
	  out_pixel[1] = in_pixel[3];

	  in_pixel += 4;
	  out_pixel += 2;
      }

      gegl_buffer_set (output, result_rect, output->format, out_buf);

      g_free (in_buf);
      g_free (out_buf);
  }

  gegl_operation_set_data (operation, context_id, "output", G_OBJECT (output));

  return TRUE;
}

#endif

-- 
Mark Probst
  http://www.complang.tuwien.ac.at/schani/
  http://www.flickr.com/photos/schani/
  http://schani.wordpress.com/