gimp/plug-ins/common/grid.c

/* GIMP - The GNU Image Manipulation Program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

/* Original plug-in coded by Tim Newsome.
 *
 * Changed to make use of real-life units by Sven Neumann <sven@gimp.org>.
 *
 * The interface code is heavily commented in the hope that it will
 * help other plug-in developers to adapt their plug-ins to make use
 * of the gimp_size_entry functionality.
 *
 * Note: There is a convenience constructor called gimp_coordinetes_new ()
 *       which simplifies the task of setting up a standard X,Y sizeentry.
 *
 * For more info and bugs see libgimp/gimpsizeentry.h and libgimp/gimpwidgets.h
 *
 * May 2000 tim copperfield [timecop@japan.co.jp]
 * http://www.ne.jp/asahi/linux/timecop
 * Added dynamic preview.  Due to weird implementation of signals from all
 * controls, preview will not auto-update.  But this plugin isn't really
 * crying for real-time updating either.
 *
 */

#include "config.h"

#include <string.h>

#include <libgimp/gimp.h>
#include <libgimp/gimpui.h>

#include "libgimp/stdplugins-intl.h"


#define PLUG_IN_PROC        "plug-in-grid"
#define PLUG_IN_BINARY      "grid"
#define PLUG_IN_ROLE        "gimp-grid"
#define SPIN_BUTTON_WIDTH    8
#define COLOR_BUTTON_WIDTH  55


typedef struct _Grid      Grid;
typedef struct _GridClass GridClass;

struct _Grid
{
  GimpPlugIn           parent_instance;

  GimpDrawable        *drawable;
  GimpProcedureConfig *config;
  GtkWidget           *hcolor_button;
  GtkWidget           *vcolor_button;
  GtkWidget           *icolor_button;
  GtkWidget           *color_chain;
};

struct _GridClass
{
  GimpPlugInClass parent_class;
};


#define GRID_TYPE  (grid_get_type ())
#define GRID(obj) (G_TYPE_CHECK_INSTANCE_CAST ((obj), GRID_TYPE, Grid))

GType                   grid_get_type         (void) G_GNUC_CONST;

static GList          * grid_query_procedures (GimpPlugIn           *plug_in);
static GimpProcedure  * grid_create_procedure (GimpPlugIn           *plug_in,
                                               const gchar          *name);

static GimpValueArray * grid_run              (GimpProcedure        *procedure,
                                               GimpRunMode           run_mode,
                                               GimpImage            *image,
                                               GimpDrawable        **drawables,
                                               GimpProcedureConfig  *config,
                                               gpointer              run_data);

static guchar           best_cmap_match       (const guchar         *cmap,
                                               gint                  ncolors,
                                               GeglColor            *color);
static void             render_grid           (GimpImage            *image,
                                               GimpDrawable         *drawable,
                                               GimpProcedureConfig  *config,
                                               GimpPreview          *preview);
static gint             dialog                (GimpImage            *image,
                                               GimpDrawable         *drawable,
                                               GimpProcedure        *procedure,
                                               GimpProcedureConfig  *config);


G_DEFINE_TYPE (Grid, grid, GIMP_TYPE_PLUG_IN)

GIMP_MAIN (GRID_TYPE)
DEFINE_STD_SET_I18N


static gint sx1, sy1, sx2, sy2;

static GtkWidget *main_dialog    = NULL;


static void
grid_class_init (GridClass *klass)
{
  GimpPlugInClass *plug_in_class = GIMP_PLUG_IN_CLASS (klass);

  plug_in_class->query_procedures = grid_query_procedures;
  plug_in_class->create_procedure = grid_create_procedure;
  plug_in_class->set_i18n         = STD_SET_I18N;
}

static void
grid_init (Grid *grid)
{
}

static GList *
grid_query_procedures (GimpPlugIn *plug_in)
{
  return g_list_append (NULL, g_strdup (PLUG_IN_PROC));
}

static GimpProcedure *
grid_create_procedure (GimpPlugIn  *plug_in,
                       const gchar *name)
{
  GimpProcedure *procedure = NULL;

  if (! strcmp (name, PLUG_IN_PROC))
    {
      GeglColor *default_hcolor;
      GeglColor *default_vcolor;
      GeglColor *default_icolor;

      gegl_init (NULL, NULL);

      default_hcolor = gegl_color_new ("black");
      default_vcolor = gegl_color_new ("black");
      default_icolor = gegl_color_new ("black");

      procedure = gimp_image_procedure_new (plug_in, name,
                                            GIMP_PDB_PROC_TYPE_PLUGIN,
                                            grid_run, NULL, NULL);

      gimp_procedure_set_image_types (procedure, "*");
      gimp_procedure_set_sensitivity_mask (procedure,
                                           GIMP_PROCEDURE_SENSITIVE_DRAWABLE);

      gimp_procedure_set_menu_label (procedure, _("_Grid (legacy)..."));
      gimp_procedure_add_menu_path (procedure,
                                    "<Image>/Filters/Render/Pattern");

      gimp_procedure_set_documentation (procedure,
                                        _("Draw a grid on the image"),
                                        "Draws a grid using the specified "
                                        "colors. The grid origin is the "
                                        "upper left corner.",
                                        name);
      gimp_procedure_set_attribution (procedure,
                                      "Tim Newsome",
                                      "Tim Newsome, Sven Neumann, "
                                      "Tom Rathborne, TC",
                                      "1997 - 2000");

      gimp_procedure_add_int_argument (procedure, "hwidth",
                                       "H width",
                                       "Horizontal width",
                                       0, GIMP_MAX_IMAGE_SIZE, 1,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "hspace",
                                       "H space",
                                       "Horizontal spacing",
                                       1, GIMP_MAX_IMAGE_SIZE, 16,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "hoffset",
                                       "H offset",
                                       "Horizontal offset",
                                       0, GIMP_MAX_IMAGE_SIZE, 8,
                                       G_PARAM_READWRITE);

      /* TODO: for "hcolor", "icolor" and "vcolor", the original code would use
       * the foreground color as default. Future work would be to get the
       * foreground/background color from context.
       */
      gimp_procedure_add_color_argument (procedure, "hcolor",
                                         "H color",
                                         "Horizontal color",
                                         TRUE, default_hcolor,
                                         G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "vwidth",
                                       "V width",
                                       "Vertical width",
                                       0, GIMP_MAX_IMAGE_SIZE, 1,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "vspace",
                                       "V space",
                                       "Vertical spacing",
                                       1, GIMP_MAX_IMAGE_SIZE, 16,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "voffset",
                                       "V offset",
                                       "Vertical offset",
                                       0, GIMP_MAX_IMAGE_SIZE, 8,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_color_argument (procedure, "vcolor",
                                         "V color",
                                         "Vertical color",
                                         TRUE, default_vcolor,
                                         G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "iwidth",
                                       "I width",
                                       "Intersection width",
                                       0, GIMP_MAX_IMAGE_SIZE, 0,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "ispace",
                                       "I space",
                                       "Intersection spacing",
                                       1, GIMP_MAX_IMAGE_SIZE, 2,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_int_argument (procedure, "ioffset",
                                       "I offset",
                                       "Intersection offset",
                                       0, GIMP_MAX_IMAGE_SIZE, 6,
                                       G_PARAM_READWRITE);

      gimp_procedure_add_color_argument (procedure, "icolor",
                                         "I color",
                                         "Intersection color",
                                         TRUE, default_icolor,
                                         G_PARAM_READWRITE);

      g_object_unref (default_hcolor);
      g_object_unref (default_vcolor);
      g_object_unref (default_icolor);
    }

  return procedure;
}

static GimpValueArray *
grid_run (GimpProcedure        *procedure,
          GimpRunMode           run_mode,
          GimpImage            *image,
          GimpDrawable        **drawables,
          GimpProcedureConfig  *config,
          gpointer              run_data)
{
  GimpDrawable *drawable;

  gegl_init (NULL, NULL);

  if (gimp_core_object_array_get_length ((GObject **) drawables) != 1)
    {
      GError *error = NULL;

      g_set_error (&error, GIMP_PLUG_IN_ERROR, 0,
                   _("Procedure '%s' only works with one drawable."),
                   PLUG_IN_PROC);

      return gimp_procedure_new_return_values (procedure,
                                               GIMP_PDB_CALLING_ERROR,
                                               error);
    }
  else
    {
      drawable = drawables[0];
    }

  if (run_mode == GIMP_RUN_INTERACTIVE && ! dialog (image, drawable, procedure, config))
    return gimp_procedure_new_return_values (procedure,
                                             GIMP_PDB_CANCEL,
                                             NULL);

  gimp_progress_init (_("Drawing grid"));

  render_grid (image, drawable, config, NULL);

  if (run_mode != GIMP_RUN_NONINTERACTIVE)
    gimp_displays_flush ();

  return gimp_procedure_new_return_values (procedure, GIMP_PDB_SUCCESS, NULL);
}


#define MAXDIFF 195076

static guchar
best_cmap_match (const guchar  *cmap,
                 gint           ncolors,
                 GeglColor     *color)
{
  guchar cmap_index = 0;
  gint   max        = MAXDIFF;
  gint   i, diff, sum;
  guchar rgb[3];

  gegl_color_get_pixel (color, babl_format ("R'G'B' u8"), rgb);

  for (i = 0; i < ncolors; i++)
    {
      diff = rgb[0] - *cmap++;
      sum = SQR (diff);
      diff = rgb[1] - *cmap++;
      sum += SQR (diff);
      diff = rgb[2] - *cmap++;
      sum += SQR (diff);

      if (sum < max)
        {
          cmap_index = i;
          max = sum;
        }
    }

  return cmap_index;
}

static inline void
pix_composite (guchar   *p1,
               guchar    p2[4],
               gint      bytes,
               gboolean  blend,
               gboolean  alpha)
{
  gint b;
  gint alpha_index;

  alpha_index = alpha ? (bytes - 1) : bytes;

  if (blend)
    {
      if (alpha)
        bytes--;

      for (b = 0; b < bytes; b++)
        {
          *p1 = *p1 * (1.0 - p2[alpha_index] / 255.0) +
                p2[b] * p2[alpha_index] / 255.0;
          p1++;
        }
    }
  else
    {
      /* blend should only be TRUE for indexed (bytes == 1) */
      *p1++ = *p2;
    }

  if (alpha && *p1 < 255)
    {
      b = *p1 + 255.0 * ((gdouble) p2[alpha_index] / (255.0 - *p1));

      *p1 = b > 255 ? 255 : b;
    }
}

static void
render_grid (GimpImage           *image,
             GimpDrawable        *drawable,
             GimpProcedureConfig *config,
             GimpPreview         *preview)
{
  GeglBuffer *src_buffer  = NULL;
  GeglBuffer *dest_buffer = NULL;
  const Babl *format;
  gint        bytes;
  gint        x_offset;
  gint        y_offset;
  guchar     *dest        = NULL;
  guchar     *buffer      = NULL;
  gint        x, y;
  gboolean    alpha;
  gboolean    blend;
  guchar      hcolor[4];
  guchar      vcolor[4];
  guchar      icolor[4];
  guchar     *cmap;
  gint        ncolors;

  gint        hwidth;
  gint        hspace;
  gint        hoffset;
  GeglColor  *hcolor_gegl;
  gint        vwidth;
  gint        vspace;
  gint        voffset;
  GeglColor  *vcolor_gegl;
  gint        iwidth;
  gint        ispace;
  gint        ioffset;
  GeglColor  *icolor_gegl;

  g_object_get (config,
                "hwidth",  &hwidth,
                "hspace",  &hspace,
                "hoffset", &hoffset,
                "hcolor",  &hcolor_gegl,
                "vwidth",  &vwidth,
                "vspace",  &vspace,
                "voffset", &voffset,
                "vcolor",  &vcolor_gegl,
                "iwidth",  &iwidth,
                "ispace",  &ispace,
                "ioffset", &ioffset,
                "icolor",  &icolor_gegl,
                NULL);

  if (hcolor_gegl == NULL)
    hcolor_gegl = gegl_color_new ("black");
  if (vcolor_gegl == NULL)
    vcolor_gegl = gegl_color_new ("black");
  if (icolor_gegl == NULL)
    icolor_gegl = gegl_color_new ("black");

  alpha = gimp_drawable_has_alpha (drawable);

  switch (gimp_image_get_base_type (image))
    {
    case GIMP_RGB:
      blend = TRUE;

      if (alpha)
        format = babl_format ("R'G'B'A u8");
      else
        format = babl_format ("R'G'B' u8");

      gegl_color_get_pixel (hcolor_gegl, babl_format ("R'G'B'A u8"), hcolor);
      gegl_color_get_pixel (vcolor_gegl, babl_format ("R'G'B'A u8"), vcolor);
      gegl_color_get_pixel (icolor_gegl, babl_format ("R'G'B'A u8"), icolor);
      break;

    case GIMP_GRAY:
      blend = TRUE;

      if (alpha)
        format = babl_format ("Y'A u8");
      else
        format = babl_format ("Y' u8");

      gegl_color_get_pixel (hcolor_gegl, babl_format ("Y'A u8"), hcolor);
      gegl_color_get_pixel (vcolor_gegl, babl_format ("Y'A u8"), vcolor);
      gegl_color_get_pixel (icolor_gegl, babl_format ("Y'A u8"), icolor);
      break;

    case GIMP_INDEXED:
      cmap = gimp_palette_get_colormap (gimp_image_get_palette (image), babl_format ("R'G'B' u8"), &ncolors, NULL);

      hcolor[0] = best_cmap_match (cmap, ncolors, hcolor_gegl);
      vcolor[0] = best_cmap_match (cmap, ncolors, vcolor_gegl);
      icolor[0] = best_cmap_match (cmap, ncolors, icolor_gegl);

      g_free (cmap);
      blend = FALSE;

      format = gimp_drawable_get_format (drawable);
      break;

    default:
      g_assert_not_reached ();
      blend = FALSE;
    }

  g_clear_object (&hcolor_gegl);
  g_clear_object (&vcolor_gegl);
  g_clear_object (&icolor_gegl);

  bytes = babl_format_get_bytes_per_pixel (format);

  if (preview)
    {
      gimp_preview_get_position (preview, &sx1, &sy1);
      gimp_preview_get_size (preview, &sx2, &sy2);

      buffer = g_new (guchar, bytes * sx2 * sy2);

      sx2 += sx1;
      sy2 += sy1;
    }
  else
    {
      gint w, h;

      if (! gimp_drawable_mask_intersect (drawable,
                                          &sx1, &sy1, &w, &h))
        return;

      sx2 = sx1 + w;
      sy2 = sy1 + h;

      dest_buffer = gimp_drawable_get_shadow_buffer (drawable);
    }

  src_buffer = gimp_drawable_get_buffer (drawable);

  dest = g_new (guchar, (sx2 - sx1) * bytes);

  for (y = sy1; y < sy2; y++)
    {
      gegl_buffer_get (src_buffer, GEGL_RECTANGLE (sx1, y, sx2 - sx1, 1), 1.0,
                       format, dest,
                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);

      y_offset = y - hoffset;
      while (y_offset < 0)
        y_offset += hspace;

      if ((y_offset + (hwidth / 2)) % hspace < hwidth)
        {
          for (x = sx1; x < sx2; x++)
            {
              pix_composite (&dest[(x-sx1) * bytes],
                             hcolor, bytes, blend, alpha);
            }
        }

      for (x = sx1; x < sx2; x++)
        {
          x_offset = vspace + x - voffset;
          while (x_offset < 0)
            x_offset += vspace;

          if ((x_offset + (vwidth / 2)) % vspace < vwidth)
            {
              pix_composite (&dest[(x-sx1) * bytes],
                             vcolor, bytes, blend, alpha);
            }

          if ((x_offset + (iwidth / 2)) % vspace < iwidth
              &&
              ((y_offset % hspace >= ispace
                &&
                y_offset % hspace < ioffset)
               ||
               (hspace -
                (y_offset % hspace) >= ispace
                &&
                hspace -
                (y_offset % hspace) < ioffset)))
            {
              pix_composite (&dest[(x-sx1) * bytes],
                             icolor, bytes, blend, alpha);
            }
        }

      if ((y_offset + (iwidth / 2)) % hspace < iwidth)
        {
          for (x = sx1; x < sx2; x++)
            {
              x_offset = vspace + x - voffset;
              while (x_offset < 0)
                x_offset += vspace;

              if ((x_offset % vspace >= ispace
                   &&
                   x_offset % vspace < ioffset)
                  ||
                  (vspace -
                   (x_offset % vspace) >= ispace
                   &&
                   vspace -
                   (x_offset % vspace) < ioffset))
                {
                  pix_composite (&dest[(x-sx1) * bytes],
                                 icolor, bytes, blend, alpha);
                }
            }
        }

      if (preview)
        {
          memcpy (buffer + (y - sy1) * (sx2 - sx1) * bytes,
                  dest,
                  (sx2 - sx1) * bytes);
        }
      else
        {
          gegl_buffer_set (dest_buffer,
                           GEGL_RECTANGLE (sx1, y, sx2 - sx1, 1), 0,
                           format, dest,
                           GEGL_AUTO_ROWSTRIDE);

          if (y % 16 == 0)
            gimp_progress_update ((gdouble) y / (gdouble) (sy2 - sy1));
        }
    }

  g_free (dest);

  g_object_unref (src_buffer);

  if (preview)
    {
      gimp_preview_draw_buffer (preview, buffer, bytes * (sx2 - sx1));
      g_free (buffer);
    }
  else
    {
      gimp_progress_update (1.0);

      g_object_unref (dest_buffer);

      gimp_drawable_merge_shadow (drawable, TRUE);
      gimp_drawable_update (drawable,
                            sx1, sy1, sx2 - sx1, sy2 - sy1);
    }
}


/***************************************************
 * GUI stuff
 */


static void
update_values (Grid *grid)
{
  GtkWidget *entry;
  GeglColor *color;

  entry = g_object_get_data (G_OBJECT (main_dialog), "width");
  g_object_set (grid->config,
                "hwidth",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 0)),
                "vwidth",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 1)),
                "iwidth",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 2)),
                NULL);

  entry = g_object_get_data (G_OBJECT (main_dialog), "space");
  g_object_set (grid->config,
                "hspace",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 0)),
                "vspace",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 1)),
                "ispace",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 2)),
                NULL);

  entry = g_object_get_data (G_OBJECT (main_dialog), "offset");
  g_object_set (grid->config,
                "hoffset",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 0)),
                "voffset",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 1)),
                "ioffset",
                (gint) RINT (gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (entry), 2)),
                NULL);

  color = gimp_color_button_get_color (GIMP_COLOR_BUTTON (grid->hcolor_button));
  g_object_set (grid->config, "hcolor", color, NULL);
  g_object_unref (color);

  color = gimp_color_button_get_color (GIMP_COLOR_BUTTON (grid->vcolor_button));
  g_object_set (grid->config, "vcolor", color, NULL);
  g_object_unref (color);

  color = gimp_color_button_get_color (GIMP_COLOR_BUTTON (grid->icolor_button));
  g_object_set (grid->config, "icolor", color, NULL);
  g_object_unref (color);
}

static void
update_preview (GimpPreview *preview,
                Grid        *grid)
{
  update_values (grid);

  render_grid (gimp_item_get_image (GIMP_ITEM (grid->drawable)),
               grid->drawable, grid->config, preview);
}

static void
entry_callback (GtkWidget *widget,
                gpointer   data)
{
  static gdouble x = -1.0;
  static gdouble y = -1.0;
  gdouble new_x;
  gdouble new_y;

  new_x = gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (widget), 0);
  new_y = gimp_size_entry_get_refval (GIMP_SIZE_ENTRY (widget), 1);

  if (gimp_chain_button_get_active (GIMP_CHAIN_BUTTON (data)))
    {
      if (new_x != x)
        {
          y = new_y = x = new_x;
          gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (widget), 1, y);
        }
      if (new_y != y)
        {
          x = new_x = y = new_y;
          gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (widget), 0, x);
        }
    }
  else
    {
      x = new_x;
      y = new_y;
    }
}

static void
color_callback (GtkWidget *widget,
                gpointer   data)
{
  Grid      *grid         = GRID (data);
  GtkWidget *chain_button = grid->color_chain;
  GeglColor *color;

  color = gimp_color_button_get_color (GIMP_COLOR_BUTTON (widget));

  if (gimp_chain_button_get_active (GIMP_CHAIN_BUTTON (chain_button)))
    {
      if (widget == grid->vcolor_button)
        {
          g_signal_handlers_block_by_func (grid->hcolor_button, color_callback,
                                           grid);
          gimp_color_button_set_color (GIMP_COLOR_BUTTON (grid->hcolor_button),
                                       color);
          g_signal_handlers_unblock_by_func (grid->hcolor_button,
                                             color_callback, grid);
        }
      else if (widget == grid->hcolor_button)
        {
          g_signal_handlers_block_by_func (grid->vcolor_button, color_callback,
                                           grid);
          gimp_color_button_set_color (GIMP_COLOR_BUTTON (grid->vcolor_button),
                                       color);
          g_signal_handlers_unblock_by_func (grid->vcolor_button,
                                             color_callback, grid);
        }
    }

  if (widget == grid->hcolor_button)
    g_object_set (grid->config, "hcolor", color, NULL);
  else if (widget == grid->vcolor_button)
    g_object_set (grid->config, "vcolor", color, NULL);
  else if (widget == grid->icolor_button)
    g_object_set (grid->config, "icolor", color, NULL);

  g_object_unref (color);
}


static gint
dialog (GimpImage           *image,
        GimpDrawable        *drawable,
        GimpProcedure       *procedure,
        GimpProcedureConfig *config)
{
  Grid            *grid;
  GimpColorConfig *color_config;
  GtkWidget       *dlg;
  GtkWidget       *main_vbox;
  GtkWidget       *vbox;
  GtkSizeGroup    *group;
  GtkWidget       *label;
  GtkWidget       *preview;
  GtkWidget       *width;
  GtkWidget       *space;
  GtkWidget       *offset;
  GtkWidget       *chain_button;
  GimpUnit        *unit;
  gint             d_width;
  gint             d_height;
  gdouble          xres;
  gdouble          yres;
  gboolean         run;

  gint             hwidth;
  gint             hspace;
  gint             hoffset;
  GeglColor       *hcolor;
  gint             vwidth;
  gint             vspace;
  gint             voffset;
  GeglColor       *vcolor;
  gint             iwidth;
  gint             ispace;
  gint             ioffset;
  GeglColor       *icolor;

  g_return_val_if_fail (main_dialog == NULL, FALSE);

  g_object_get (config,
                "hwidth",  &hwidth,
                "hspace",  &hspace,
                "hoffset", &hoffset,
                "hcolor",  &hcolor,
                "vwidth",  &vwidth,
                "vspace",  &vspace,
                "voffset", &voffset,
                "vcolor",  &vcolor,
                "iwidth",  &iwidth,
                "ispace",  &ispace,
                "ioffset", &ioffset,
                "icolor",  &icolor,
                NULL);

  gimp_ui_init (PLUG_IN_BINARY);

  d_width  = gimp_drawable_get_width  (drawable);
  d_height = gimp_drawable_get_height (drawable);

  main_dialog = dlg = gimp_dialog_new (_("Grid"), PLUG_IN_ROLE,
                                       NULL, 0,
                                       gimp_standard_help_func, PLUG_IN_PROC,

                                       _("_Cancel"), GTK_RESPONSE_CANCEL,
                                       _("_OK"),     GTK_RESPONSE_OK,

                                       NULL);

  gimp_dialog_set_alternative_button_order (GTK_DIALOG (dlg),
                                           GTK_RESPONSE_OK,
                                           GTK_RESPONSE_CANCEL,
                                           -1);

  gimp_window_set_transient (GTK_WINDOW (dlg));

  /*  Get the image resolution and unit  */
  gimp_image_get_resolution (image, &xres, &yres);
  unit = gimp_image_get_unit (image);

  main_vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 12);
  gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 12);
  gtk_box_pack_start (GTK_BOX (gtk_dialog_get_content_area (GTK_DIALOG (dlg))),
                      main_vbox, TRUE, TRUE, 0);
  gtk_widget_show (main_vbox);

  preview = gimp_drawable_preview_new_from_drawable (drawable);
  gtk_box_pack_start (GTK_BOX (main_vbox), preview, TRUE, TRUE, 0);
  gtk_widget_show (preview);

  grid = GRID (gimp_procedure_get_plug_in (procedure));
  grid->drawable = drawable;
  grid->config   = config;
  g_signal_connect (preview, "invalidated",
                    G_CALLBACK (update_preview),
                    grid);

  vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 2);
  gtk_box_pack_start (GTK_BOX (main_vbox), vbox, FALSE, FALSE, 0);
  gtk_widget_show (vbox);

  /*  The width entries  */
  width = gimp_size_entry_new (3,                            /*  number_of_fields  */
                               unit,                         /*  unit              */
                               "%a",                         /*  unit_format       */
                               TRUE,                         /*  menu_show_pixels  */
                               TRUE,                         /*  menu_show_percent */
                               FALSE,                        /*  show_refval       */
                               SPIN_BUTTON_WIDTH,            /*  spinbutton_usize  */
                               GIMP_SIZE_ENTRY_UPDATE_SIZE); /*  update_policy     */

  gtk_box_pack_start (GTK_BOX (vbox), width, FALSE, FALSE, 0);
  gtk_widget_show (width);

  /*  set the unit back to pixels, since most times we will want pixels */
  gimp_size_entry_set_unit (GIMP_SIZE_ENTRY (width), gimp_unit_pixel ());

  /*  set the resolution to the image resolution  */
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (width), 0, xres, TRUE);
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (width), 1, yres, TRUE);
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (width), 2, xres, TRUE);

  /*  set the size (in pixels) that will be treated as 0% and 100%  */
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (width), 0, 0.0, d_height);
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (width), 1, 0.0, d_width);
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (width), 2, 0.0, d_width);

  /*  set upper and lower limits (in pixels)  */
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (width), 0, 0.0,
                                         d_height);
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (width), 1, 0.0,
                                         d_width);
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (width), 2, 0.0,
                                         MAX (d_width, d_height));
  gtk_grid_set_column_spacing (GTK_GRID (width), 6);

  /*  initialize the values  */
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (width), 0, hwidth);
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (width), 1, vwidth);
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (width), 2, iwidth);

  /*  attach labels  */
  gimp_size_entry_attach_label (GIMP_SIZE_ENTRY (width), _("Horizontal\nLines"),
                                0, 1, 0.0);
  gimp_size_entry_attach_label (GIMP_SIZE_ENTRY (width), _("Vertical\nLines"),
                                0, 2, 0.0);
  gimp_size_entry_attach_label (GIMP_SIZE_ENTRY (width), _("Intersection"),
                                0, 3, 0.0);

  label = gimp_size_entry_attach_label (GIMP_SIZE_ENTRY (width), _("Width:"),
                                        1, 0, 0.0);

  group = gtk_size_group_new (GTK_SIZE_GROUP_HORIZONTAL);
  gtk_size_group_add_widget (group, label);
  g_object_unref (group);

  /*  put a chain_button under the size_entries  */
  chain_button = gimp_chain_button_new (GIMP_CHAIN_BOTTOM);
  if (hwidth == vwidth)
    gimp_chain_button_set_active (GIMP_CHAIN_BUTTON (chain_button), TRUE);
  gtk_grid_attach (GTK_GRID (width), chain_button, 1, 2, 2, 1);
  gtk_widget_show (chain_button);

  /* connect to the 'value-changed' signal because we have to take care
   * of keeping the entries in sync when the chainbutton is active
   */
  g_signal_connect (width, "value-changed",
                    G_CALLBACK (entry_callback),
                    chain_button);
  g_signal_connect_swapped (width, "value-changed",
                            G_CALLBACK (gimp_preview_invalidate),
                            preview);

  /*  The spacing entries  */
  space = gimp_size_entry_new (3,                            /*  number_of_fields  */
                               unit,                         /*  unit              */
                               "%a",                         /*  unit_format       */
                               TRUE,                         /*  menu_show_pixels  */
                               TRUE,                         /*  menu_show_percent */
                               FALSE,                        /*  show_refval       */
                               SPIN_BUTTON_WIDTH,            /*  spinbutton_usize  */
                               GIMP_SIZE_ENTRY_UPDATE_SIZE); /*  update_policy     */

  gtk_box_pack_start (GTK_BOX (vbox), space, FALSE, FALSE, 0);
  gtk_widget_show (space);

  gimp_size_entry_set_unit (GIMP_SIZE_ENTRY (space), gimp_unit_pixel ());

  /*  set the resolution to the image resolution  */
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (space), 0, xres, TRUE);
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (space), 1, yres, TRUE);
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (space), 2, xres, TRUE);

  /*  set the size (in pixels) that will be treated as 0% and 100%  */
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (space), 0, 0.0, d_height);
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (space), 1, 0.0, d_width);
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (space), 2, 0.0, d_width);

  /*  set upper and lower limits (in pixels)  */
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (space), 0, 1.0,
                                         d_height);
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (space), 1, 1.0,
                                         d_width);
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (space), 2, 0.0,
                                         MAX (d_width, d_height));
  gtk_grid_set_column_spacing (GTK_GRID (space), 6);

  /*  initialize the values  */
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (space), 0, hspace);
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (space), 1, vspace);
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (space), 2, ispace);

  /*  attach labels  */
  label = gimp_size_entry_attach_label (GIMP_SIZE_ENTRY (space), _("Spacing:"),
                                        1, 0, 0.0);
  gtk_size_group_add_widget (group, label);

  /*  put a chain_button under the spacing_entries  */
  chain_button = gimp_chain_button_new (GIMP_CHAIN_BOTTOM);
  if (hspace == vspace)
    gimp_chain_button_set_active (GIMP_CHAIN_BUTTON (chain_button), TRUE);
  gtk_grid_attach (GTK_GRID (space), chain_button, 1, 2, 2, 1);
  gtk_widget_show (chain_button);

  /* connect to the 'value-changed' and "unit-changed" signals because
   * we have to take care of keeping the entries in sync when the
   * chainbutton is active
   */
  g_signal_connect (space, "value-changed",
                    G_CALLBACK (entry_callback),
                    chain_button);
  g_signal_connect (space, "unit-changed",
                    G_CALLBACK (entry_callback),
                    chain_button);
  g_signal_connect_swapped (space, "value-changed",
                            G_CALLBACK (gimp_preview_invalidate),
                            preview);

  /*  The offset entries  */
  offset = gimp_size_entry_new (3,                            /*  number_of_fields  */
                                unit,                         /*  unit              */
                                "%a",                         /*  unit_format       */
                                TRUE,                         /*  menu_show_pixels  */
                                TRUE,                         /*  menu_show_percent */
                                FALSE,                        /*  show_refval       */
                                SPIN_BUTTON_WIDTH,            /*  spinbutton_usize  */
                                GIMP_SIZE_ENTRY_UPDATE_SIZE); /*  update_policy     */

  gtk_box_pack_start (GTK_BOX (vbox), offset, FALSE, FALSE, 0);
  gtk_widget_show (offset);

  gimp_size_entry_set_unit (GIMP_SIZE_ENTRY (offset), gimp_unit_pixel ());

  /*  set the resolution to the image resolution  */
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (offset), 0, xres, TRUE);
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (offset), 1, yres, TRUE);
  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (offset), 2, xres, TRUE);

  /*  set the size (in pixels) that will be treated as 0% and 100%  */
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (offset), 0, 0.0, d_height);
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (offset), 1, 0.0, d_width);
  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (offset), 2, 0.0, d_width);

  /*  set upper and lower limits (in pixels)  */
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (offset), 0, 0.0,
                                         d_height);
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (offset), 1, 0.0,
                                         d_width);
  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (offset), 2, 0.0,
                                         MAX (d_width, d_height));
  gtk_grid_set_column_spacing (GTK_GRID (offset), 6);

  /*  initialize the values  */
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (offset), 0, hoffset);
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (offset), 1, voffset);
  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (offset), 2, ioffset);

  /*  attach labels  */
  label = gimp_size_entry_attach_label (GIMP_SIZE_ENTRY (offset), _("Offset:"),
                                        1, 0, 0.0);
  gtk_size_group_add_widget (group, label);

  /*  put a chain_button under the offset_entries  */
  chain_button = gimp_chain_button_new (GIMP_CHAIN_BOTTOM);
  if (hoffset == voffset)
    gimp_chain_button_set_active (GIMP_CHAIN_BUTTON (chain_button), TRUE);
  gtk_grid_attach (GTK_GRID (offset), chain_button, 1, 2, 2, 1);
  gtk_widget_show (chain_button);

  /* connect to the 'value-changed' and "unit-changed" signals because
   * we have to take care of keeping the entries in sync when the
   * chainbutton is active
   */
  g_signal_connect (offset, "value-changed",
                    G_CALLBACK (entry_callback),
                    chain_button);
  g_signal_connect (offset, "unit-changed",
                    G_CALLBACK (entry_callback),
                    chain_button);
  g_signal_connect_swapped (offset, "value-changed",
                            G_CALLBACK (gimp_preview_invalidate),
                            preview);

  /*  put a chain_button under the color_buttons  */
  grid->color_chain = gimp_chain_button_new (GIMP_CHAIN_BOTTOM);
  if (gimp_color_is_perceptually_identical (hcolor, vcolor))
    gimp_chain_button_set_active (GIMP_CHAIN_BUTTON (grid->color_chain), TRUE);
  gtk_grid_attach (GTK_GRID (offset), grid->color_chain, 1, 4, 2, 1);
  gtk_widget_show (grid->color_chain);

  /*  attach color selectors  */
  grid->hcolor_button = gimp_color_button_new (_("Horizontal Color"),
                                               COLOR_BUTTON_WIDTH, 16,
                                               hcolor,
                                               GIMP_COLOR_AREA_SMALL_CHECKS);
  gimp_color_button_set_update (GIMP_COLOR_BUTTON (grid->hcolor_button), TRUE);
  gtk_grid_attach (GTK_GRID (offset), grid->hcolor_button, 1, 3, 1, 1);
  gtk_widget_show (grid->hcolor_button);

  color_config = gimp_get_color_configuration ();
  gimp_color_button_set_color_config (GIMP_COLOR_BUTTON (grid->hcolor_button),
                                      color_config);

  g_signal_connect (grid->hcolor_button, "color-changed",
                    G_CALLBACK (color_callback),
                    grid);
  g_signal_connect_swapped (grid->hcolor_button, "color-changed",
                            G_CALLBACK (gimp_preview_invalidate),
                            preview);

  grid->vcolor_button = gimp_color_button_new (_("Vertical Color"),
                                               COLOR_BUTTON_WIDTH, 16,
                                               vcolor,
                                               GIMP_COLOR_AREA_SMALL_CHECKS);
  gimp_color_button_set_update (GIMP_COLOR_BUTTON (grid->vcolor_button), TRUE);
  gtk_grid_attach (GTK_GRID (offset), grid->vcolor_button, 2, 3, 1, 1);
  gtk_widget_show (grid->vcolor_button);

  gimp_color_button_set_color_config (GIMP_COLOR_BUTTON (grid->vcolor_button),
                                      color_config);

  g_signal_connect (grid->vcolor_button, "color-changed",
                    G_CALLBACK (color_callback),
                    grid);
  g_signal_connect_swapped (grid->vcolor_button, "color-changed",
                            G_CALLBACK (gimp_preview_invalidate),
                            preview);

  grid->icolor_button = gimp_color_button_new (_("Intersection Color"),
                                               COLOR_BUTTON_WIDTH, 16,
                                               icolor,
                                               GIMP_COLOR_AREA_SMALL_CHECKS);
  gimp_color_button_set_update (GIMP_COLOR_BUTTON (grid->icolor_button), TRUE);
  gtk_grid_attach (GTK_GRID (offset), grid->icolor_button, 3, 3, 1, 1);
  gtk_widget_show (grid->icolor_button);

  gimp_color_button_set_color_config (GIMP_COLOR_BUTTON (grid->icolor_button),
                                      color_config);
  g_object_unref (color_config);
  g_object_unref (hcolor);
  g_object_unref (vcolor);
  g_object_unref (icolor);

  g_signal_connect (grid->icolor_button, "color-changed",
                    G_CALLBACK (color_callback),
                    grid);
  g_signal_connect_swapped (grid->icolor_button, "color-changed",
                            G_CALLBACK (gimp_preview_invalidate),
                            preview);

  gtk_widget_show (dlg);

  g_object_set_data (G_OBJECT (dlg), "width",  width);
  g_object_set_data (G_OBJECT (dlg), "space",  space);
  g_object_set_data (G_OBJECT (dlg), "offset", offset);

  run = (gimp_dialog_run (GIMP_DIALOG (dlg)) == GTK_RESPONSE_OK);

  if (run)
    update_values (grid);

  gtk_widget_destroy (dlg);

  return run;
}