/* GIMP - The GNU Image Manipulation Program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * gimpoperationerasemode.c
 * Copyright (C) 2008 Michael Natterer <mitch@gimp.org>
 *               2012 Ville Sokk <ville.sokk@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include "config.h"

#include <gegl-plugin.h>

#include "gimp-gegl-types.h"

#include "gimpoperationerasemode.h"


static gboolean gimp_operation_erase_mode_process (GeglOperation       *operation,
                                                   void                *in_buf,
                                                   void                *aux_buf,
                                                   void                *out_buf,
                                                   glong                samples,
                                                   const GeglRectangle *roi,
                                                   gint                 level);


G_DEFINE_TYPE (GimpOperationEraseMode, gimp_operation_erase_mode,
               GIMP_TYPE_OPERATION_POINT_LAYER_MODE)


static void
gimp_operation_erase_mode_class_init (GimpOperationEraseModeClass *klass)
{
  GeglOperationClass              *operation_class;
  GeglOperationPointComposerClass *point_class;

  operation_class = GEGL_OPERATION_CLASS (klass);
  point_class     = GEGL_OPERATION_POINT_COMPOSER_CLASS (klass);

  gegl_operation_class_set_keys (operation_class,
                                 "name",        "gimp:erase-mode",
                                 "description", "GIMP erase mode operation",
                                 NULL);

  point_class->process         = gimp_operation_erase_mode_process;
}

static void
gimp_operation_erase_mode_init (GimpOperationEraseMode *self)
{
}

static gboolean
gimp_operation_erase_mode_process (GeglOperation       *operation,
                                   void                *in_buf,
                                   void                *aux_buf,
                                   void                *out_buf,
                                   glong                samples,
                                   const GeglRectangle *roi,
                                   gint                 level)
{
  GimpOperationPointLayerMode *point = GIMP_OPERATION_POINT_LAYER_MODE (operation);
  gfloat                      *in    = in_buf;
  gfloat                      *layer = aux_buf;
  gfloat                      *out   = out_buf;

  if (point->premultiplied)
    {
      while (samples--)
        {
          gint b;

          out[ALPHA] = in[ALPHA] - in[ALPHA] * layer[ALPHA];
          for (b = RED; b < ALPHA; b++)
            {
              out[b] = in[b] / in[ALPHA] * out[ALPHA];
            }

          in    += 4;
          layer += 4;
          out   += 4;
        }
    }
  else
    {
      while (samples--)
        {
          gint b;

          for (b = RED; b < ALPHA; b++)
            {
              out[b] = in[b];
            }
          out[ALPHA] = in[ALPHA] - in[ALPHA] * layer[ALPHA];;

          in    += 4;
          layer += 4;
          out   += 4;
        }
    }

  return TRUE;
}
