GIMP cel plug-in

gistfile1.c

/* GIMP - The GNU Image Manipulation Program
 * Copyright (C) 1995 Spencer Kimball and Peter Mattis
 *
 * cel.c -- KISS CEL file format plug-in
 * (copyright) 1997,1998 Nick Lamb ([email protected])
 *
 * 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/>.
 */

#include "config.h"

#include <errno.h>
#include <string.h>

#include <glib/gstdio.h>

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

#include "libgimp/stdplugins-intl.h"


#define LOAD_PROC      "file-cel-load"
#define SAVE_PROC      "file-cel-save"
#define PLUG_IN_BINARY "file-cel"
#define PLUG_IN_ROLE   "gimp-file-cel"


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

static gint      load_palette   (const gchar  *file,
                                 FILE         *fp,
                                 guchar        palette[],
                                 GError      **error);
static gint32    load_image     (const gchar  *file,
                                 const gchar  *brief,
                                 GError      **error);
static gboolean  save_image     (const gchar  *file,
                                 const gchar  *brief,
                                 gint32        image,
                                 gint32        layer,
                                 GError      **error);
static void      palette_dialog (const gchar  *title);
static gboolean  need_palette   (const gchar  *file,
                                 GError      **error);


/* Globals... */

const GimpPlugInInfo  PLUG_IN_INFO =
{
  NULL,  /* init_proc  */
  NULL,  /* quit_proc  */
  query, /* query_proc */
  run,   /* run_proc   */
};

static gchar *palette_file = NULL;
static gsize  data_length  = 0;

/* Let GIMP library handle initialisation (and inquisitive users) */

MAIN ()

/* GIMP queries plug-in for parameters etc. */

static void
query (void)
{
  static const GimpParamDef load_args[] =
  {
    { GIMP_PDB_INT32,  "run-mode",         "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }"  },
    { GIMP_PDB_STRING, "filename",         "Filename to load image from"   },
    { GIMP_PDB_STRING, "raw-filename",     "Name entered"                  },
    { GIMP_PDB_STRING, "palette-filename", "Filename to load palette from" }
  };
  static const GimpParamDef load_return_vals[] =
  {
    { GIMP_PDB_IMAGE, "image", "Output image" }
  };

  static const GimpParamDef save_args[] =
  {
    { GIMP_PDB_INT32,    "run-mode",         "The run mode { RUN-INTERACTIVE (0), RUN-NONINTERACTIVE (1) }" },
    { GIMP_PDB_IMAGE,    "image",            "Input image"                  },
    { GIMP_PDB_DRAWABLE, "drawable",         "Drawable to save"             },
    { GIMP_PDB_STRING,   "filename",         "Filename to save image to"    },
    { GIMP_PDB_STRING,   "raw-filename",     "Name entered"                 },
    { GIMP_PDB_STRING,   "palette-filename", "Filename to save palette to"  },
  };

  gimp_install_procedure (LOAD_PROC,
                          "Loads files in KISS CEL file format",
                          "This plug-in loads individual KISS cell files.",
                          "Nick Lamb",
                          "Nick Lamb <[email protected]>",
                          "May 1998",
                          N_("KISS CEL"),
                          NULL,
                          GIMP_PLUGIN,
                          G_N_ELEMENTS (load_args),
                          G_N_ELEMENTS (load_return_vals),
                          load_args, load_return_vals);

  gimp_register_magic_load_handler (LOAD_PROC,
                                    "cel",
                                    "",
                                    "0,string,KiSS\\040");

  gimp_install_procedure (SAVE_PROC,
                          "Saves files in KISS CEL file format",
                          "This plug-in saves individual KISS cell files.",
                          "Nick Lamb",
                          "Nick Lamb <[email protected]>",
                          "May 1998",
                          N_("KISS CEL"),
                          "RGB*, INDEXED*",
                          GIMP_PLUGIN,
                          G_N_ELEMENTS (save_args), 0,
                          save_args, NULL);

  gimp_register_save_handler (SAVE_PROC, "cel", "");
}

static void
run (const gchar      *name,
     gint              nparams,
     const GimpParam  *param,
     gint             *nreturn_vals,
     GimpParam       **return_vals)
{
  static GimpParam   values[2]; /* Return values */
  GimpRunMode        run_mode;
  gint32             image_ID;
  gint32             drawable_ID;
  GimpPDBStatusType  status = GIMP_PDB_SUCCESS;
  gint32             image;
  GimpExportReturn   export = GIMP_EXPORT_CANCEL;
  GError            *error  = NULL;
  gint               needs_palette = 0;

  run_mode = param[0].data.d_int32;

  INIT_I18N ();

  /* Set up default return values */

  *nreturn_vals = 1;
  *return_vals  = values;
  values[0].type          = GIMP_PDB_STATUS;
  values[0].data.d_status = GIMP_PDB_EXECUTION_ERROR;

  if (strcmp (name, LOAD_PROC) == 0)
    {
      if (run_mode != GIMP_RUN_NONINTERACTIVE)
        {
          data_length = gimp_get_data_size (SAVE_PROC);
          if (data_length > 0)
            {
              palette_file = g_malloc (data_length);
              gimp_get_data (SAVE_PROC, palette_file);
            }
          else
            {
              palette_file = g_strdup ("*.kcf");
              data_length = strlen (palette_file) + 1;
            }
        }

      if (run_mode == GIMP_RUN_NONINTERACTIVE)
        {
          palette_file = param[3].data.d_string;
          if (palette_file)
            data_length = strlen (palette_file) + 1;
          else
            data_length = 0;
        }
      else if (run_mode == GIMP_RUN_INTERACTIVE)
        {
          /* Let user choose KCF palette (cancel ignores) */
          needs_palette = need_palette (param[1].data.d_string, &error);

          if (! error)
            {
              if (needs_palette)
                palette_dialog (_("Load KISS Palette"));

              gimp_set_data (SAVE_PROC, palette_file, data_length);
            }
        }

      if (! error)
        {
          image = load_image (param[1].data.d_string, param[2].data.d_string,
                              &error);

          if (image != -1)
            {
              *nreturn_vals = 2;
              values[1].type         = GIMP_PDB_IMAGE;
              values[1].data.d_image = image;
            }
          else
            {
              status = GIMP_PDB_EXECUTION_ERROR;
            }
        }
      else
        {
          status = GIMP_PDB_EXECUTION_ERROR;
        }
    }
  else if (strcmp (name, SAVE_PROC) == 0)
    {
      image_ID      = param[1].data.d_int32;
      drawable_ID   = param[2].data.d_int32;

      /*  eventually export the image */
      switch (run_mode)
        {
        case GIMP_RUN_INTERACTIVE:
        case GIMP_RUN_WITH_LAST_VALS:
          gimp_ui_init (PLUG_IN_BINARY, FALSE);

          export = gimp_export_image (&image_ID, &drawable_ID, "CEL",
                                      GIMP_EXPORT_CAN_HANDLE_RGB   |
                                      GIMP_EXPORT_CAN_HANDLE_ALPHA |
                                      GIMP_EXPORT_CAN_HANDLE_INDEXED);

          if (export == GIMP_EXPORT_CANCEL)
            {
              values[0].data.d_status = GIMP_PDB_CANCEL;
              return;
            }
          break;
        default:
          break;
        }

      if (save_image (param[3].data.d_string, param[4].data.d_string,
                      image_ID, drawable_ID, &error))
        {
          gimp_set_data (SAVE_PROC, palette_file, data_length);
        }
      else
        {
          status = GIMP_PDB_EXECUTION_ERROR;
        }

      if (export == GIMP_EXPORT_EXPORT)
        gimp_image_delete (image_ID);
    }
  else
    {
      status = GIMP_PDB_CALLING_ERROR;
    }

  if (status != GIMP_PDB_SUCCESS && error)
    {
      *nreturn_vals = 2;
      values[1].type          = GIMP_PDB_STRING;
      values[1].data.d_string = error->message;
    }

  values[0].data.d_status = status;
}

/* Peek into the file to determine whether we need a palette */
static gboolean
need_palette (const gchar *file,
              GError     **error)
{
  FILE   *fp;
  guchar  header[32];
  size_t  n_read;

  fp = g_fopen (file, "rb");
  if (fp == NULL)
    {
      g_set_error (error, G_FILE_ERROR, g_file_error_from_errno (errno),
                   _("Could not open '%s' for reading: %s"),
                   gimp_filename_to_utf8 (file), g_strerror (errno));
      return FALSE;
    }

  n_read = fread (header, 32, 1, fp);

  fclose (fp);

  if (n_read < 1)
    {
      g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                   _("EOF or error while reading image header"));
      return FALSE;
    }

  return (header[5] < 32);
}

/* Load CEL image into GIMP */

static gint32
load_image (const gchar  *file,
            const gchar  *brief,
            GError      **error)
{
  FILE      *fp;            /* Read file pointer */
  guchar     header[32],    /* File header */
             file_mark,     /* KiSS file type */
             bpp;           /* Bits per pixel */
  gint       height, width, /* Dimensions of image */
             offx, offy,    /* Layer offets */
             colours;       /* Number of colours */

  gint32     image,         /* Image */
             layer;         /* Layer */
  guchar    *palette,       /* 24 bit palette */
            *buffer,        /* Temporary buffer */
            *line;          /* Pixel data */
  GimpDrawable *drawable;   /* Drawable for layer */
  GimpPixelRgn  pixel_rgn;  /* Pixel region for layer */

  gint       i, j, k;       /* Counters */
  size_t     n_read;        /* Number of items read from file */


  /* Open the file for reading */
  fp = g_fopen (file, "r");

  if (fp == NULL)
    {
      g_set_error (error, G_FILE_ERROR, g_file_error_from_errno (errno),
                   _("Could not open '%s' for reading: %s"),
                   gimp_filename_to_utf8 (file), g_strerror (errno));
      return -1;
    }

  gimp_progress_init_printf (_("Opening '%s'"),
                             gimp_filename_to_utf8 (brief));

  /* Get the image dimensions and create the image... */

  n_read = fread (header, 4, 1, fp);

  if (n_read < 1)
    {
      g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                   _("EOF or error while reading image header"));
      return -1;
    }

  if (strncmp ((const gchar *) header, "KiSS", 4))
    {
      colours= 16;
      bpp = 4;
      width = header[0] + (256 * header[1]);
      height = header[2] + (256 * header[3]);
      offx= 0;
      offy= 0;
    }
  else
    { /* New-style image file, read full header */
      n_read = fread (header, 28, 1, fp);

      if (n_read < 1)
        {
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("EOF or error while reading image header"));
          return -1;
        }

      file_mark = header[0];
      if (file_mark != 0x20 && file_mark != 0x21)
        {
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("is not a CEL image file"));
          return -1;
        }

      bpp = header[1];
      switch (bpp)
        {
        case 4:
        case 8:
        case 32:
          colours = (1 << bpp);
          break;
        default:
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("illegal bpp value in image: %hhu"), bpp);
          return -1;
        }

      width = header[4] + (256 * header[5]);
      height = header[6] + (256 * header[7]);
      offx = header[8] + (256 * header[9]);
      offy = header[10] + (256 * header[11]);
    }

  if ((width == 0) || (height == 0) || (width + offx > GIMP_MAX_IMAGE_SIZE) ||
      (height + offy > GIMP_MAX_IMAGE_SIZE))
    {
      g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                   _("illegal image dimensions: width: %d, horizontal offset: "
                     "%d, height: %d, vertical offset: %d"),
                   width, offx, height, offy);
      return -1;
    }

  if (bpp == 32)
    image = gimp_image_new (width + offx, height + offy, GIMP_RGB);
  else
    image = gimp_image_new (width + offx, height + offy, GIMP_INDEXED);

  if (image == -1)
    {
      g_set_error (error, 0, 0, _("Can't create a new image"));
      fclose (fp);
      return -1;
    }

  gimp_image_set_filename (image, file);

  /* Create an indexed-alpha layer to hold the image... */
  if (bpp == 32)
    layer = gimp_layer_new (image, _("Background"), width, height,
                            GIMP_RGBA_IMAGE, 100, GIMP_NORMAL_MODE);
  else
    layer = gimp_layer_new (image, _("Background"), width, height,
                            GIMP_INDEXEDA_IMAGE, 100, GIMP_NORMAL_MODE);
  gimp_image_insert_layer (image, layer, -1, 0);
  gimp_layer_set_offsets (layer, offx, offy);

  /* Get the drawable and set the pixel region for our load... */

  drawable = gimp_drawable_get (layer);

  gimp_pixel_rgn_init (&pixel_rgn, drawable, 0, 0, drawable->width,
                       drawable->height, TRUE, FALSE);

  /* Read the image in and give it to GIMP a line at a time */
  buffer = g_new (guchar, width * 4);
  line   = g_new (guchar, (width + 1) * 4);

  for (i = 0; i < height && !feof(fp); ++i)
    {
      switch (bpp)
        {
        case 4:
          n_read = fread (buffer, (width+1)/2, 1, fp);

          if (n_read < 1)
            {
              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                           _("EOF or error while reading image data"));
              return -1;
            }

          for (j = 0, k = 0; j < width*2; j+= 4, ++k)
            {
              if (buffer[k] / 16 == 0)
                {
                  line[j]= 16;
                  line[j+1]= 0;
                }
              else
                {
                  line[j]= (buffer[k] / 16) - 1;
                  line[j+1]= 255;
                }
              if (buffer[k] % 16 == 0)
                {
                  line[j+2]= 16;
                  line[j+3]= 0;
                }
              else
                {
                  line[j+2]= (buffer[k] % 16) - 1;
                  line[j+3]= 255;
                }
            }
          break;

        case 8:
          n_read = fread (buffer, width, 1, fp);

          if (n_read < 1)
            {
              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                           _("EOF or error while reading image data"));
              return -1;
            }

          for (j = 0, k = 0; j < width*2; j+= 2, ++k)
            {
              if (buffer[k] == 0)
                {
                  line[j]= 255;
                  line[j+1]= 0;
                }
              else
                {
                  line[j]= buffer[k] - 1;
                  line[j+1]= 255;
                }
            }
          break;

        case 32:
          n_read = fread (line, width*4, 1, fp);

          if (n_read < 1)
            {
              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                           _("EOF or error while reading image data"));
              return -1;
            }

          /* The CEL file order is BGR so we need to swap B and R
           * to get the Gimp RGB order.
           */
          for (j= 0; j < width; j++)
            {
              guint8 tmp = line[j*4];
              line[j*4] = line[j*4+2];
              line[j*4+2] = tmp;
            }
          break;

        default:
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("Unsupported bit depth (%d)!"), bpp);
          return -1;
        }

      gimp_pixel_rgn_set_rect (&pixel_rgn, line, 0, i, drawable->width, 1);
      gimp_progress_update ((float) i / (float) height);
    }
  gimp_progress_update (1.0);

  /* Close image files, give back allocated memory */

  fclose (fp);
  g_free (buffer);
  g_free (line);

  if (bpp != 32)
    {
      /* Use palette from file or otherwise default grey palette */
      guchar palette[256*3];

      /* Open the file for reading if user picked one */
      if (palette_file == NULL)
        {
          fp = NULL;
        }
      else
        {
          fp = g_fopen (palette_file, "r");

          if (fp == NULL)
            {
              g_set_error (error, G_FILE_ERROR, g_file_error_from_errno (errno),
                           _("Could not open '%s' for reading: %s"),
                           gimp_filename_to_utf8 (palette_file),
                           g_strerror (errno));
              return -1;
            }
        }

      if (fp != NULL)
        {
          colours = load_palette (palette_file, fp, palette, error);
          fclose (fp);
          if (colours < 0 || *error)
            return -1;
        }
      else
        {
          for (i= 0; i < colours; ++i)
            {
              palette[i*3] = palette[i*3+1] = palette[i*3+2]= i * 256 / colours;
            }
        }

      gimp_image_set_colormap (image, palette + 3, colours - 1);
    }

  /* Now get everything redrawn and hand back the finished image */

  gimp_drawable_flush (drawable);
  gimp_drawable_detach (drawable);

  return image;
}

static gint
load_palette (const gchar *file,
              FILE        *fp,
              guchar       palette[],
              GError     **error)
{
  guchar        header[32];     /* File header */
  guchar        buffer[2];
  guchar        file_mark, bpp;
  gint          i, colours = 0;
  size_t        n_read;

  n_read = fread (header, 4, 1, fp);

  if (n_read < 1)
    {
      g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                   _("'%s': EOF or error while reading palette header"),
                   gimp_filename_to_utf8 (file));
      return -1;
    }

  if (!strncmp ((const gchar *) header, "KiSS", 4))
    {
      n_read = fread (header+4, 28, 1, fp);

      if (n_read < 1)
        {
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("'%s': EOF or error while reading palette header"),
                       gimp_filename_to_utf8 (file));
          return -1;
        }

      file_mark = header[4];
      if (file_mark != 0x10)
        {
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("'%s': is not a KCF palette file"),
                       gimp_filename_to_utf8 (file));
          return -1;
        }

      bpp = header[5];
      if (bpp != 12 && bpp != 24)
        {
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("'%s': illegal bpp value in palette: %hhu"),
                       gimp_filename_to_utf8 (file), bpp);
          return -1;
        }

      colours = header[8] + header[9] * 256;
      if (colours != 16 && colours != 256)
        {
          g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                       _("'%s': illegal number of colors: %u"),
                       gimp_filename_to_utf8 (file), colours);
          return -1;
        }

      switch (bpp)
        {
        case 12:
          for (i = 0; i < colours; ++i)
            {
              n_read = fread (buffer, 1, 2, fp);

              if (n_read < 2)
                {
                  g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                               _("'%s': EOF or error while reading "
                                 "palette data"),
                               gimp_filename_to_utf8 (file));
                  return -1;
                }

              palette[i*3]= buffer[0] & 0xf0;
              palette[i*3+1]= (buffer[1] & 0x0f) * 16;
              palette[i*3+2]= (buffer[0] & 0x0f) * 16;
            }
          break;
        case 24:
          n_read = fread (palette, colours, 3, fp);

          if (n_read < 3)
            {
              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                           _("'%s': EOF or error while reading palette data"),
                           gimp_filename_to_utf8 (file));
              return -1;
            }
          break;
        default:
          g_assert_not_reached ();
        }
    }
  else
    {
      colours = 16;
      fseek (fp, 0, SEEK_SET);
      for (i= 0; i < colours; ++i)
        {
          n_read = fread (buffer, 1, 2, fp);

          if (n_read < 2)
            {
              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
                           _("'%s': EOF or error while reading palette data"),
                           gimp_filename_to_utf8 (file));
              return -1;
            }

          palette[i*3] = buffer[0] & 0xf0;
          palette[i*3+1] = (buffer[1] & 0x0f) * 16;
          palette[i*3+2] = (buffer[0] & 0x0f) * 16;
        }
    }

  return colours;
}

static gboolean
save_image (const gchar  *file,
            const gchar  *brief,
            gint32        image,
            gint32        layer,
            GError      **error)
{
  FILE          *fp;            /* Write file pointer */
  guchar         header[32];    /* File header */
  gint           bpp;           /* Bit per pixel */
  gint           colours, type; /* Number of colours, type of layer */
  gint           offx, offy;    /* Layer offsets */

  guchar        *buffer;        /* Temporary buffer */
  guchar        *line;          /* Pixel data */
  GimpDrawable  *drawable;      /* Drawable for layer */
  GimpPixelRgn   pixel_rgn;     /* Pixel region for layer */

  gint           i, j, k;       /* Counters */

  /* Check that this is an indexed image, fail otherwise */
  type = gimp_drawable_type (layer);
  if (type != GIMP_INDEXEDA_IMAGE)
    bpp = 32;
  else
    bpp = 4;

  /* Find out how offset this layer was */
  gimp_drawable_offsets (layer, &offx, &offy);

  drawable = gimp_drawable_get (layer);

  /* Open the file for writing */
  fp = g_fopen (file, "w");

  if (fp == NULL)
    {
      g_set_error (error, G_FILE_ERROR, g_file_error_from_errno (errno),
                   _("Could not open '%s' for writing: %s"),
                   gimp_filename_to_utf8 (file), g_strerror (errno));
      return FALSE;
    }

  gimp_progress_init_printf (_("Saving '%s'"),
                             gimp_filename_to_utf8 (brief));

  /* Headers */
  memset (header, 0, 32);
  strcpy ((gchar *) header, "KiSS");
  header[4]= 0x20;

  /* Work out whether to save as 8bit or 4bit */
  if (bpp < 32)
    {
      g_free (gimp_image_get_colormap (image, &colours));
      if (colours > 15)
        {
          header[5] = 8;
        }
      else
        {
          header[5] = 4;
        }
    }
  else
    header[5] = 32;

  /* Fill in the blanks ... */
  header[8]  = drawable->width % 256;
  header[9]  = drawable->width / 256;
  header[10] = drawable->height % 256;
  header[11] = drawable->height / 256;
  header[12] = offx % 256;
  header[13] = offx / 256;
  header[14] = offy % 256;
  header[15] = offy / 256;
  fwrite (header, 32, 1, fp);

  /* Arrange for memory etc. */
  gimp_pixel_rgn_init (&pixel_rgn, drawable, 0, 0, drawable->width,
                       drawable->height, TRUE, FALSE);
  buffer = g_new (guchar, drawable->width*4);
  line = g_new (guchar, (drawable->width+1) * 4);

  /* Get the image from GIMP one line at a time and write it out */
  for (i = 0; i < drawable->height; ++i)
    {
      gimp_pixel_rgn_get_rect (&pixel_rgn, line, 0, i, drawable->width, 1);
      memset (buffer, 0, drawable->width);

      if (bpp == 32)
        {
          for (j = 0; j < drawable->width; j++)
            {
              buffer[4*j] = line[4*j+2];     /* B */
              buffer[4*j+1] = line[4*j+1];   /* G */
              buffer[4*j+2] = line[4*j+0];   /* R */
              buffer[4*j+3] = line[4*j+3];   /* Alpha */
            }
          fwrite (buffer, drawable->width, 4, fp);
        }
      else if (colours > 16)
        {
          for (j = 0, k = 0; j < drawable->width*2; j+= 2, ++k)
            {
              if (line[j+1] > 127)
                {
                  buffer[k]= line[j] + 1;
                }
            }
          fwrite (buffer, drawable->width, 1, fp);
        }
      else
        {
          for (j = 0, k = 0; j < drawable->width*2; j+= 4, ++k)
            {
              buffer[k] = 0;
              if (line[j+1] > 127)
                {
                  buffer[k] += (line[j] + 1)<< 4;
                }
              if (line[j+3] > 127)
                {
                  buffer[k] += (line[j+2] + 1);
                }
            }
          fwrite (buffer, (drawable->width+1)/2, 1, fp);
        }

      gimp_progress_update ((float) i / (float) drawable->height);
    }
  gimp_progress_update (1.0);

  /* Close files, give back allocated memory */
  fclose (fp);
  g_free (buffer);
  g_free (line);

  return TRUE;
}

static void
palette_dialog (const gchar *title)
{
  GtkWidget *dialog;

  gimp_ui_init (PLUG_IN_BINARY, FALSE);

  dialog = gtk_file_chooser_dialog_new (title, NULL,
                                        GTK_FILE_CHOOSER_ACTION_OPEN,

                                        GTK_STOCK_CANCEL, GTK_RESPONSE_CANCEL,
                                        GTK_STOCK_OPEN,   GTK_RESPONSE_OK,

                                        NULL);

  gtk_dialog_set_alternative_button_order (GTK_DIALOG (dialog),
                                           GTK_RESPONSE_OK,
                                           GTK_RESPONSE_CANCEL,
                                           -1);

  gtk_file_chooser_set_filename (GTK_FILE_CHOOSER (dialog), palette_file);

  gtk_dialog_set_default_response (GTK_DIALOG (dialog), GTK_RESPONSE_OK);

  gtk_widget_show (dialog);

  if (gtk_dialog_run (GTK_DIALOG (dialog)) == GTK_RESPONSE_OK)
    {
      g_free (palette_file);
      palette_file = gtk_file_chooser_get_filename (GTK_FILE_CHOOSER (dialog));
      data_length = strlen (palette_file) + 1;
    }

  gtk_widget_destroy (dialog);
}