/* GIMP - The GNU Image Manipulation Program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * gimppickable.c
 * Copyright (C) 2004  Michael Natterer <mitch@gimp.org>
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

/* This file contains an interface for pixel objects that their color at
 * a given position can be picked. Also included is a utility for
 * sampling an average area (which uses the implemented picking
 * functions).
 */

#include "config.h"

#include <string.h>

#include <cairo.h>
#include <gegl.h>
#include <gdk-pixbuf/gdk-pixbuf.h>

#include "libgimpcolor/gimpcolor.h"

#include "core-types.h"

#include "gimpobject.h"
#include "gimpimage.h"
#include "gimppickable.h"


static void   gimp_pickable_interface_base_init (GimpPickableInterface *iface);


GType
gimp_pickable_interface_get_type (void)
{
  static GType pickable_iface_type = 0;

  if (! pickable_iface_type)
    {
      const GTypeInfo pickable_iface_info =
      {
        sizeof (GimpPickableInterface),
        (GBaseInitFunc)     gimp_pickable_interface_base_init,
        (GBaseFinalizeFunc) NULL,
      };

      pickable_iface_type = g_type_register_static (G_TYPE_INTERFACE,
                                                    "GimpPickableInterface",
                                                    &pickable_iface_info,
                                                    0);

      g_type_interface_add_prerequisite (pickable_iface_type, GIMP_TYPE_OBJECT);
    }

  return pickable_iface_type;
}

static void
gimp_pickable_interface_base_init (GimpPickableInterface *iface)
{
  static gboolean initialized = FALSE;

  if (! initialized)
    {
      g_object_interface_install_property (iface,
                                           g_param_spec_object ("buffer",
                                                                NULL, NULL,
                                                                GEGL_TYPE_BUFFER,
                                                                GIMP_PARAM_READABLE));

      initialized = TRUE;
    }
}

void
gimp_pickable_flush (GimpPickable *pickable)
{
  GimpPickableInterface *pickable_iface;

  g_return_if_fail (GIMP_IS_PICKABLE (pickable));

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->flush)
    pickable_iface->flush (pickable);
}

GimpImage *
gimp_pickable_get_image (GimpPickable *pickable)
{
  GimpPickableInterface *pickable_iface;

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->get_image)
    return pickable_iface->get_image (pickable);

  return NULL;
}

const Babl *
gimp_pickable_get_format (GimpPickable *pickable)
{
  GimpPickableInterface *pickable_iface;

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->get_format)
    return pickable_iface->get_format (pickable);

  return NULL;
}

const Babl *
gimp_pickable_get_format_with_alpha (GimpPickable *pickable)
{
  GimpPickableInterface *pickable_iface;

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->get_format_with_alpha)
    return pickable_iface->get_format_with_alpha (pickable);

  return NULL;
}

GeglBuffer *
gimp_pickable_get_buffer (GimpPickable *pickable)
{
  GimpPickableInterface *pickable_iface;

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), NULL);

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->get_buffer)
    return pickable_iface->get_buffer (pickable);

  return NULL;
}

gboolean
gimp_pickable_get_pixel_at (GimpPickable *pickable,
                            gint          x,
                            gint          y,
                            const Babl   *format,
                            gpointer      pixel)
{
  GimpPickableInterface *pickable_iface;

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);
  g_return_val_if_fail (pixel != NULL, FALSE);

  if (! format)
    format = gimp_pickable_get_format (pickable);

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->get_pixel_at)
    return pickable_iface->get_pixel_at (pickable, x, y, format, pixel);

  return FALSE;
}

gboolean
gimp_pickable_get_color_at (GimpPickable *pickable,
                            gint          x,
                            gint          y,
                            GimpRGB      *color)
{
  guchar pixel[32];

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);
  g_return_val_if_fail (color != NULL, FALSE);

  if (! gimp_pickable_get_pixel_at (pickable, x, y, NULL, pixel))
    return FALSE;

  gimp_rgba_set_pixel (color, gimp_pickable_get_format (pickable), pixel);

  return TRUE;
}

gdouble
gimp_pickable_get_opacity_at (GimpPickable *pickable,
                              gint          x,
                              gint          y)
{
  GimpPickableInterface *pickable_iface;

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), GIMP_OPACITY_TRANSPARENT);

  pickable_iface = GIMP_PICKABLE_GET_INTERFACE (pickable);

  if (pickable_iface->get_opacity_at)
    return pickable_iface->get_opacity_at (pickable, x, y);

  return GIMP_OPACITY_TRANSPARENT;
}

gboolean
gimp_pickable_pick_color (GimpPickable *pickable,
                          gint          x,
                          gint          y,
                          gboolean      sample_average,
                          gdouble       average_radius,
                          gpointer      pixel,
                          GimpRGB      *color)
{
  const Babl *format;
  gdouble     sample[4];

  g_return_val_if_fail (GIMP_IS_PICKABLE (pickable), FALSE);

  format = gimp_pickable_get_format (pickable);

  if (! gimp_pickable_get_pixel_at (pickable, x, y, format, sample))
    return FALSE;

  gimp_rgba_set_pixel (color, format, sample);

  if (pixel)
    memcpy (pixel, sample, babl_format_get_bytes_per_pixel (format));

  if (sample_average)
    {
      gint    count        = 0;
      gdouble color_avg[4] = { 0.0, 0.0, 0.0, 0.0 };
      gint    radius       = (gint) average_radius;
      gint    i, j;

      format = babl_format ("RGBA double");

      for (i = x - radius; i <= x + radius; i++)
        for (j = y - radius; j <= y + radius; j++)
          if (gimp_pickable_get_pixel_at (pickable, i, j, format, sample))
            {
              count++;

              color_avg[RED]   += sample[RED];
              color_avg[GREEN] += sample[GREEN];
              color_avg[BLUE]  += sample[BLUE];
              color_avg[ALPHA] += sample[ALPHA];
            }

      sample[RED]   = color_avg[RED]   / count;
      sample[GREEN] = color_avg[GREEN] / count;
      sample[BLUE]  = color_avg[BLUE]  / count;
      sample[ALPHA] = color_avg[ALPHA] / count;

      gimp_rgba_set_pixel (color, format, sample);
    }

  return TRUE;
}
