GIMPのプラグインをc言語で作ってみる。

#include <libgimp/gimp.h>

static void query (void);
static void run   (const gchar      *name,
                   gint              nparams,
                   const GimpParam  *param,
                   gint             *nreturn_vals,
                   GimpParam       **return_vals);
static void my_bluefill  (GimpDrawable *drawable);

GimpPlugInInfo PLUG_IN_INFO =
{
  NULL,
  NULL,
  query,
  run
};

MAIN()

static void
query (void)
{
  static GimpParamDef args[] =
  {
    {
      GIMP_PDB_INT32,
      "run-mode",
      "Run mode"
    },
    {
      GIMP_PDB_IMAGE,
      "image",
      "Input image"
    },
    {
      GIMP_PDB_DRAWABLE,
      "drawable",
      "Input drawable"
    }
  };

  gimp_install_procedure (
    "plug-in-my-bluefill",
    "My Blue Fill",
    "MyBlueFill",
    "May Work",
    "Copyright MayWork",
    "2022",
    "MyBlueFill...",
    "RGB*, GRAY*",
    GIMP_PLUGIN,
    G_N_ELEMENTS (args), 0,
    args, NULL);

  gimp_plugin_menu_register ("plug-in-my-bluefill",
                             "<Image>/Filters/Misc");
}

static void
run (const gchar      *name,
     gint              nparams,
     const GimpParam  *param,
     gint             *nreturn_vals,
     GimpParam       **return_vals)
{
  static GimpParam  values[1];
  GimpPDBStatusType status = GIMP_PDB_SUCCESS;
  GimpRunMode       run_mode;
  GimpDrawable *drawable;

  *nreturn_vals = 1;
  *return_vals  = values;

  values[0].type = GIMP_PDB_STATUS;
  values[0].data.d_status = status;

  run_mode = param[0].data.d_int32;

  gimp_progress_init ("Blue Fill Runing...");

  drawable = gimp_drawable_get (param[2].data.d_drawable);
  my_bluefill (drawable);

  gimp_displays_flush ();
  gimp_drawable_detach (drawable);

  return;
}

static void
my_bluefill (GimpDrawable *drawable)
{
  gint         i, channels, image_id, drawable_id;
  gint         x1, y1, x2, y2;
  GimpPixelRgn rgn_out;
  guchar      *outrow;
  GeglRectangle roi;
  gboolean non_empty;
  
  drawable_id = drawable->drawable_id;
  image_id = gimp_item_get_image (drawable_id);
  gimp_selection_bounds(image_id, &non_empty, &x1, &y1, &x2, &y2);
  if (non_empty == FALSE)
    return;

  channels = gimp_drawable_bpp (drawable->drawable_id);

  gimp_pixel_rgn_init (&rgn_out,
                       drawable,
                       x1, y1,
                       x2 - x1, y2 - y1,
                       TRUE, TRUE);

  outrow = g_new (guchar, channels * (x2 - x1));
  
  for(i = 0; i < (channels * (x2 - x1)); i += channels)
  {
      outrow[i] = 0;
      outrow[i+1] = 0;
      outrow[i+2] = 255;
  }

  for (i = y1; i < y2; i++)
  {
    gimp_pixel_rgn_set_row (&rgn_out, outrow, x1, i, x2 - x1);

    if (i % 10 == 0)
        gimp_progress_update ((gdouble) (i - y1) / (gdouble) (y2 - y1));
    }

  g_free (outrow);

  gimp_drawable_flush (drawable);
  gimp_drawable_merge_shadow (drawable->drawable_id, TRUE);
  gimp_drawable_update (drawable->drawable_id,
                        x1, y1,
                        x2 - x1, y2 - y1);

}