Adding upstream version 2.10.36.upstream/2.10.36

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1387 insertions, 0 deletions

diff --git a/plug-ins/file-tiff/file-tiff-save.c b/plug-ins/file-tiff/file-tiff-save.c
new file mode 100644
index 0000000..0def177
--- /dev/null
+++ b/plug-ins/file-tiff/file-tiff-save.c
@@ -0,0 +1,1387 @@
+/* tiff exporting for GIMP
+ *  -Peter Mattis
+ *
+ * The TIFF loading code has been completely revamped by Nick Lamb
+ * njl195@zepler.org.uk -- 18 May 1998
+ * And it now gains support for tiles (and doubtless a zillion bugs)
+ * njl195@zepler.org.uk -- 12 June 1999
+ * LZW patent fuss continues :(
+ * njl195@zepler.org.uk -- 20 April 2000
+ * The code for this filter is based on "tifftopnm" and "pnmtotiff",
+ *  2 programs that are a part of the netpbm package.
+ * khk@khk.net -- 13 May 2000
+ * Added support for ICCPROFILE tiff tag. If this tag is present in a
+ * TIFF file, then a parasite is created and vice versa.
+ * peter@kirchgessner.net -- 29 Oct 2002
+ * Progress bar only when run interactive
+ * Added support for layer offsets - pablo.dangelo@web.de -- 7 Jan 2004
+ * Honor EXTRASAMPLES tag while loading images with alphachannel
+ * pablo.dangelo@web.de -- 16 Jan 2004
+ */
+
+/*
+ * tifftopnm.c - converts a Tagged Image File to a portable anymap
+ *
+ * Derived by Jef Poskanzer from tif2ras.c, which is:
+ *
+ * Copyright (c) 1990 by Sun Microsystems, Inc.
+ *
+ * Author: Patrick J. Naughton
+ * naughton@wind.sun.com
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation for any purpose and without fee is hereby granted,
+ * provided that the above copyright notice appear in all copies and that
+ * both that copyright notice and this permission notice appear in
+ * supporting documentation.
+ *
+ * This file is provided AS IS with no warranties of any kind.  The author
+ * shall have no liability with respect to the infringement of copyrights,
+ * trade secrets or any patents by this file or any part thereof.  In no
+ * event will the author be liable for any lost revenue or profits or
+ * other special, indirect and consequential damages.
+ */
+
+#include "config.h"
+
+#include <errno.h>
+#include <string.h>
+
+#include <tiffio.h>
+#include <gexiv2/gexiv2.h>
+
+#include <libgimp/gimp.h>
+#include <libgimp/gimpui.h>
+
+#include "file-tiff-io.h"
+#include "file-tiff-save.h"
+
+#include "libgimp/stdplugins-intl.h"
+
+
+#define PLUG_IN_ROLE "gimp-file-tiff-save"
+
+
+static gboolean  save_paths             (TIFF          *tif,
+                                         gint32         image,
+                                         gdouble        width,
+                                         gdouble        height,
+                                         gint           offset_x,
+                                         gint           offset_y);
+
+static void      comment_entry_callback (GtkWidget     *widget,
+                                         gchar        **comment);
+
+static void      byte2bit               (const guchar  *byteline,
+                                         gint           width,
+                                         guchar        *bitline,
+                                         gboolean       invert);
+
+
+static void
+double_to_psd_fixed (gdouble  value,
+                     gchar   *target)
+{
+  gdouble in, frac;
+  gint    i, f;
+
+  frac = modf (value, &in);
+  if (frac < 0)
+    {
+      in -= 1;
+      frac += 1;
+    }
+
+  i = (gint) CLAMP (in, -16, 15);
+  f = CLAMP ((gint) (frac * 0xFFFFFF), 0, 0xFFFFFF);
+
+  target[0] = i & 0xFF;
+  target[1] = (f >> 16) & 0xFF;
+  target[2] = (f >>  8) & 0xFF;
+  target[3] = f & 0xFF;
+}
+
+static gboolean
+save_paths (TIFF    *tif,
+            gint32   image,
+            gdouble  width,
+            gdouble  height,
+            gint     offset_x,
+            gint     offset_y)
+{
+  gint id = 2000; /* Photoshop paths have IDs >= 2000 */
+  gint num_vectors, *vectors, v;
+  gint num_strokes, *strokes, s;
+  GString *ps_tag;
+
+  vectors = gimp_image_get_vectors (image, &num_vectors);
+
+  if (num_vectors <= 0)
+    return FALSE;
+
+  ps_tag = g_string_new ("");
+
+  /* Only up to 1000 paths supported */
+  for (v = 0; v < MIN (num_vectors, 1000); v++)
+    {
+      GString *data;
+      gchar   *name, *nameend;
+      gsize    len;
+      gint     lenpos;
+      gchar    pointrecord[26] = { 0, };
+      gchar   *tmpname;
+      GError  *err = NULL;
+
+      data = g_string_new ("8BIM");
+      g_string_append_c (data, id / 256);
+      g_string_append_c (data, id % 256);
+
+      /*
+       * - use iso8859-1 if possible
+       * - otherwise use UTF-8, prepended with \xef\xbb\xbf (Byte-Order-Mark)
+       */
+      name = gimp_item_get_name (vectors[v]);
+      tmpname = g_convert (name, -1, "iso8859-1", "utf-8", NULL, &len, &err);
+
+      if (tmpname && err == NULL)
+        {
+          g_string_append_c (data, MIN (len, 255));
+          g_string_append_len (data, tmpname, MIN (len, 255));
+          g_free (tmpname);
+        }
+      else
+        {
+          /* conversion failed, we fall back to UTF-8 */
+          len = g_utf8_strlen (name, 255 - 3);  /* need three marker-bytes */
+
+          nameend = g_utf8_offset_to_pointer (name, len);
+          len = nameend - name; /* in bytes */
+          g_assert (len + 3 <= 255);
+
+          g_string_append_c (data, len + 3);
+          g_string_append_len (data, "\xEF\xBB\xBF", 3); /* Unicode 0xfeff */
+          g_string_append_len (data, name, len);
+
+          if (tmpname)
+            g_free (tmpname);
+        }
+
+      if (data->len % 2)  /* padding to even size */
+        g_string_append_c (data, 0);
+      g_free (name);
+
+      lenpos = data->len;
+      g_string_append_len (data, "\0\0\0\0", 4); /* will be filled in later */
+      len = data->len; /* to calculate the data size later */
+
+      pointrecord[1] = 6;  /* fill rule record */
+      g_string_append_len (data, pointrecord, 26);
+
+      strokes = gimp_vectors_get_strokes (vectors[v], &num_strokes);
+
+      for (s = 0; s < num_strokes; s++)
+        {
+          GimpVectorsStrokeType type;
+          gdouble  *points;
+          gint      num_points;
+          gboolean  closed;
+          gint      p = 0;
+
+          type = gimp_vectors_stroke_get_points (vectors[v], strokes[s],
+                                                 &num_points, &points, &closed);
+
+          if (type != GIMP_VECTORS_STROKE_TYPE_BEZIER ||
+              num_points > 65535 ||
+              num_points % 6)
+            {
+              g_printerr ("tiff-save: unsupported stroke type: "
+                          "%d (%d points)\n", type, num_points);
+              continue;
+            }
+
+          memset (pointrecord, 0, 26);
+          pointrecord[1] = closed ? 0 : 3;
+          pointrecord[2] = (num_points / 6) / 256;
+          pointrecord[3] = (num_points / 6) % 256;
+          g_string_append_len (data, pointrecord, 26);
+
+          for (p = 0; p < num_points; p += 6)
+            {
+              pointrecord[1] = closed ? 2 : 5;
+
+              double_to_psd_fixed ((points[p+1] - offset_y) / height, pointrecord + 2);
+              double_to_psd_fixed ((points[p+0] - offset_x) / width,  pointrecord + 6);
+              double_to_psd_fixed ((points[p+3] - offset_y) / height, pointrecord + 10);
+              double_to_psd_fixed ((points[p+2] - offset_x) / width,  pointrecord + 14);
+              double_to_psd_fixed ((points[p+5] - offset_y) / height, pointrecord + 18);
+              double_to_psd_fixed ((points[p+4] - offset_x) / width,  pointrecord + 22);
+
+              g_string_append_len (data, pointrecord, 26);
+            }
+        }
+
+      g_free (strokes);
+
+      /* fix up the length */
+
+      len = data->len - len;
+      data->str[lenpos + 0] = (len & 0xFF000000) >> 24;
+      data->str[lenpos + 1] = (len & 0x00FF0000) >> 16;
+      data->str[lenpos + 2] = (len & 0x0000FF00) >>  8;
+      data->str[lenpos + 3] = (len & 0x000000FF) >>  0;
+
+      g_string_append_len (ps_tag, data->str, data->len);
+      g_string_free (data, TRUE);
+      id ++;
+    }
+
+  TIFFSetField (tif, TIFFTAG_PHOTOSHOP, ps_tag->len, ps_tag->str);
+  g_string_free (ps_tag, TRUE);
+
+  g_free (vectors);
+
+  return TRUE;
+}
+
+/*
+ * pnmtotiff.c - converts a portable anymap to a Tagged Image File
+ *
+ * Derived by Jef Poskanzer from ras2tif.c, which is:
+ *
+ * Copyright (c) 1990 by Sun Microsystems, Inc.
+ *
+ * Author: Patrick J. Naughton
+ * naughton@wind.sun.com
+ *
+ * This file is provided AS IS with no warranties of any kind.  The author
+ * shall have no liability with respect to the infringement of copyrights,
+ * trade secrets or any patents by this file or any part thereof.  In no
+ * event will the author be liable for any lost revenue or profits or
+ * other special, indirect and consequential damages.
+ */
+
+static gboolean
+save_layer (TIFF         *tif,
+            TiffSaveVals *tsvals,
+            gint32        image,
+            gint32        layer,
+            gint32        page,
+            gint32        num_pages,
+            gint32        orig_image, /* the export function might */
+                                      /* have created a duplicate  */
+            gint          origin_x,
+            gint          origin_y,
+            gint         *saved_bpp,
+            gboolean      out_linear,
+            GError      **error)
+{
+  gboolean          status = FALSE;
+  gushort           red[256];
+  gushort           grn[256];
+  gushort           blu[256];
+  gint              cols, rows, row, i;
+  glong             rowsperstrip;
+  gushort           compression;
+  gushort           extra_samples[1];
+  gboolean          alpha;
+  gshort            predictor;
+  gshort            photometric;
+  const Babl       *format;
+  const Babl       *type;
+  gshort            samplesperpixel;
+  gshort            bitspersample;
+  gshort            sampleformat;
+  gint              bytesperrow;
+  guchar           *src = NULL;
+  guchar           *data = NULL;
+  guchar           *cmap;
+  gint              num_colors;
+  gint              success;
+  GimpImageType     drawable_type;
+  GeglBuffer       *buffer = NULL;
+  gint              tile_height;
+  gint              y, yend;
+  gboolean          is_bw    = FALSE;
+  gboolean          invert   = TRUE;
+  const guchar      bw_map[] = { 0, 0, 0, 255, 255, 255 };
+  const guchar      wb_map[] = { 255, 255, 255, 0, 0, 0 };
+  gchar            *layer_name = NULL;
+  const gdouble     progress_base = (gdouble) page / (gdouble) num_pages;
+  const gdouble     progress_fraction = 1.0 / (gdouble) num_pages;
+  gdouble           xresolution;
+  gdouble           yresolution;
+  gushort           save_unit = RESUNIT_INCH;
+  gint              offset_x, offset_y;
+
+  compression = tsvals->compression;
+
+  layer_name = gimp_item_get_name (layer);
+
+  /* Disabled because this isn't in older releases of libtiff, and it
+   * wasn't helping much anyway
+   */
+#if 0
+  if (TIFFFindCODEC((uint16) compression) == NULL)
+    compression = COMPRESSION_NONE; /* CODEC not available */
+#endif
+
+  predictor = 0;
+  tile_height = gimp_tile_height ();
+  rowsperstrip = tile_height;
+
+  drawable_type = gimp_drawable_type (layer);
+  buffer        = gimp_drawable_get_buffer (layer);
+
+  format = gegl_buffer_get_format (buffer);
+  type   = babl_format_get_type (format, 0);
+
+  switch (gimp_image_get_precision (image))
+    {
+    case GIMP_PRECISION_U8_LINEAR:
+    case GIMP_PRECISION_U8_GAMMA:
+      /* Promote to 16-bit if storage and export TRC don't match. */
+      if ((gimp_image_get_precision (image) == GIMP_PRECISION_U8_LINEAR && out_linear) ||
+          (gimp_image_get_precision (image) != GIMP_PRECISION_U8_LINEAR && ! out_linear))
+        {
+          bitspersample = 8;
+          sampleformat  = SAMPLEFORMAT_UINT;
+        }
+      else
+        {
+          bitspersample = 16;
+          sampleformat  = SAMPLEFORMAT_UINT;
+          type          = babl_type ("u16");
+        }
+      break;
+
+    case GIMP_PRECISION_U16_LINEAR:
+    case GIMP_PRECISION_U16_GAMMA:
+      bitspersample = 16;
+      sampleformat  = SAMPLEFORMAT_UINT;
+      break;
+
+    case GIMP_PRECISION_U32_LINEAR:
+    case GIMP_PRECISION_U32_GAMMA:
+      bitspersample = 32;
+      sampleformat  = SAMPLEFORMAT_UINT;
+      break;
+
+    case GIMP_PRECISION_HALF_LINEAR:
+    case GIMP_PRECISION_HALF_GAMMA:
+      bitspersample = 16;
+      sampleformat  = SAMPLEFORMAT_IEEEFP;
+      break;
+
+    default:
+    case GIMP_PRECISION_FLOAT_LINEAR:
+    case GIMP_PRECISION_FLOAT_GAMMA:
+      bitspersample = 32;
+      sampleformat  = SAMPLEFORMAT_IEEEFP;
+      break;
+
+    case GIMP_PRECISION_DOUBLE_LINEAR:
+    case GIMP_PRECISION_DOUBLE_GAMMA:
+      bitspersample = 64;
+      sampleformat  = SAMPLEFORMAT_IEEEFP;
+      break;
+    }
+
+  *saved_bpp = bitspersample;
+
+  cols = gegl_buffer_get_width (buffer);
+  rows = gegl_buffer_get_height (buffer);
+
+  switch (drawable_type)
+    {
+    case GIMP_RGB_IMAGE:
+      predictor       = 2;
+      samplesperpixel = 3;
+      photometric     = PHOTOMETRIC_RGB;
+      alpha           = FALSE;
+      if (out_linear)
+        {
+          format = babl_format_new (babl_model ("RGB"),
+                                    type,
+                                    babl_component ("R"),
+                                    babl_component ("G"),
+                                    babl_component ("B"),
+                                    NULL);
+        }
+      else
+        {
+          format = babl_format_new (babl_model ("R'G'B'"),
+                                    type,
+                                    babl_component ("R'"),
+                                    babl_component ("G'"),
+                                    babl_component ("B'"),
+                                    NULL);
+        }
+      break;
+
+    case GIMP_GRAY_IMAGE:
+      samplesperpixel = 1;
+      photometric     = PHOTOMETRIC_MINISBLACK;
+      alpha           = FALSE;
+      if (out_linear)
+        {
+          format = babl_format_new (babl_model ("Y"),
+                                    type,
+                                    babl_component ("Y"),
+                                    NULL);
+        }
+      else
+        {
+          format = babl_format_new (babl_model ("Y'"),
+                                    type,
+                                    babl_component ("Y'"),
+                                    NULL);
+        }
+      break;
+
+    case GIMP_RGBA_IMAGE:
+      predictor       = 2;
+      samplesperpixel = 4;
+      photometric     = PHOTOMETRIC_RGB;
+      alpha           = TRUE;
+      if (tsvals->save_transp_pixels)
+        {
+          if (out_linear)
+            {
+              format = babl_format_new (babl_model ("RGBA"),
+                                        type,
+                                        babl_component ("R"),
+                                        babl_component ("G"),
+                                        babl_component ("B"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+          else
+            {
+              format = babl_format_new (babl_model ("R'G'B'A"),
+                                        type,
+                                        babl_component ("R'"),
+                                        babl_component ("G'"),
+                                        babl_component ("B'"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+        }
+      else
+        {
+          if (out_linear)
+            {
+              format = babl_format_new (babl_model ("RaGaBaA"),
+                                        type,
+                                        babl_component ("Ra"),
+                                        babl_component ("Ga"),
+                                        babl_component ("Ba"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+          else
+            {
+              format = babl_format_new (babl_model ("R'aG'aB'aA"),
+                                        type,
+                                        babl_component ("R'a"),
+                                        babl_component ("G'a"),
+                                        babl_component ("B'a"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+        }
+      break;
+
+    case GIMP_GRAYA_IMAGE:
+      samplesperpixel = 2;
+      photometric     = PHOTOMETRIC_MINISBLACK;
+      alpha           = TRUE;
+      if (tsvals->save_transp_pixels)
+        {
+          if (out_linear)
+            {
+              format = babl_format_new (babl_model ("YA"),
+                                        type,
+                                        babl_component ("Y"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+          else
+            {
+              format = babl_format_new (babl_model ("Y'A"),
+                                        type,
+                                        babl_component ("Y'"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+        }
+      else
+        {
+          if (out_linear)
+            {
+              format = babl_format_new (babl_model ("YaA"),
+                                        type,
+                                        babl_component ("Ya"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+          else
+            {
+              format = babl_format_new (babl_model ("Y'aA"),
+                                        type,
+                                        babl_component ("Y'a"),
+                                        babl_component ("A"),
+                                        NULL);
+            }
+        }
+      break;
+
+    case GIMP_INDEXED_IMAGE:
+    case GIMP_INDEXEDA_IMAGE:
+      cmap = gimp_image_get_colormap (image, &num_colors);
+
+      if (num_colors == 2 || num_colors == 1)
+        {
+          is_bw = (memcmp (cmap, bw_map, 3 * num_colors) == 0);
+          photometric = PHOTOMETRIC_MINISWHITE;
+
+          if (!is_bw)
+            {
+              is_bw = (memcmp (cmap, wb_map, 3 * num_colors) == 0);
+
+              if (is_bw)
+                invert = FALSE;
+            }
+       }
+
+      if (is_bw)
+        {
+          bitspersample = 1;
+        }
+      else
+        {
+          bitspersample = 8;
+          photometric   = PHOTOMETRIC_PALETTE;
+
+          for (i = 0; i < num_colors; i++)
+            {
+              red[i] = cmap[i * 3 + 0] * 65535 / 255;
+              grn[i] = cmap[i * 3 + 1] * 65535 / 255;
+              blu[i] = cmap[i * 3 + 2] * 65535 / 255;
+            }
+       }
+
+      samplesperpixel = (drawable_type == GIMP_INDEXEDA_IMAGE) ? 2 : 1;
+      bytesperrow     = cols;
+      alpha           = (drawable_type == GIMP_INDEXEDA_IMAGE);
+      format          = gimp_drawable_get_format (layer);
+
+      g_free (cmap);
+      break;
+
+    default:
+      goto out;
+    }
+
+  bytesperrow = cols * babl_format_get_bytes_per_pixel (format);
+
+  if (compression == COMPRESSION_CCITTFAX3 ||
+      compression == COMPRESSION_CCITTFAX4)
+    {
+      if (bitspersample != 1 || samplesperpixel != 1)
+        {
+          const gchar *msg = _("Only monochrome pictures can be compressed "
+                               "with \"CCITT Group 4\" or \"CCITT Group 3\".");
+
+          g_set_error_literal (error, G_FILE_ERROR, G_FILE_ERROR_FAILED, msg);
+
+          goto out;
+        }
+    }
+
+  if (compression == COMPRESSION_JPEG)
+    {
+      if (gimp_image_base_type (image) == GIMP_INDEXED)
+        {
+          g_set_error_literal (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
+                               _("Indexed pictures cannot be compressed "
+                                 "with \"JPEG\"."));
+          goto out;
+        }
+    }
+
+
+  /* Set TIFF parameters. */
+  if (num_pages > 1)
+    {
+      TIFFSetField (tif, TIFFTAG_SUBFILETYPE, FILETYPE_PAGE);
+      TIFFSetField (tif, TIFFTAG_PAGENUMBER, page, num_pages);
+    }
+  TIFFSetField (tif, TIFFTAG_PAGENAME, layer_name);
+  TIFFSetField (tif, TIFFTAG_IMAGEWIDTH, cols);
+  TIFFSetField (tif, TIFFTAG_IMAGELENGTH, rows);
+  TIFFSetField (tif, TIFFTAG_BITSPERSAMPLE, bitspersample);
+  TIFFSetField (tif, TIFFTAG_SAMPLEFORMAT, sampleformat);
+  TIFFSetField (tif, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
+  TIFFSetField (tif, TIFFTAG_COMPRESSION, compression);
+
+  if ((compression == COMPRESSION_LZW ||
+       compression == COMPRESSION_ADOBE_DEFLATE) &&
+      (predictor != 0))
+    {
+      TIFFSetField (tif, TIFFTAG_PREDICTOR, predictor);
+    }
+
+  if (alpha)
+    {
+      if (tsvals->save_transp_pixels ||
+          /* Associated alpha, hence premultiplied components is
+           * meaningless for palette images with transparency in TIFF
+           * format, since alpha is set per pixel, not per color (so a
+           * given color could be set to different alpha on different
+           * pixels, hence it cannot be premultiplied).
+           */
+          drawable_type == GIMP_INDEXEDA_IMAGE)
+        extra_samples [0] = EXTRASAMPLE_UNASSALPHA;
+      else
+        extra_samples [0] = EXTRASAMPLE_ASSOCALPHA;
+
+      TIFFSetField (tif, TIFFTAG_EXTRASAMPLES, 1, extra_samples);
+    }
+
+  TIFFSetField (tif, TIFFTAG_PHOTOMETRIC, photometric);
+  TIFFSetField (tif, TIFFTAG_SAMPLESPERPIXEL, samplesperpixel);
+  TIFFSetField (tif, TIFFTAG_ROWSPERSTRIP, rowsperstrip);
+  /* TIFFSetField( tif, TIFFTAG_STRIPBYTECOUNTS, rows / rowsperstrip ); */
+  TIFFSetField (tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
+
+  /* resolution fields */
+  gimp_image_get_resolution (orig_image, &xresolution, &yresolution);
+
+  if (gimp_unit_is_metric (gimp_image_get_unit (orig_image)))
+    {
+      save_unit = RESUNIT_CENTIMETER;
+      xresolution /= 2.54;
+      yresolution /= 2.54;
+    }
+
+  if (xresolution > 1e-5 && yresolution > 1e-5)
+    {
+      TIFFSetField (tif, TIFFTAG_XRESOLUTION, xresolution);
+      TIFFSetField (tif, TIFFTAG_YRESOLUTION, yresolution);
+      TIFFSetField (tif, TIFFTAG_RESOLUTIONUNIT, save_unit);
+    }
+
+  gimp_drawable_offsets (layer, &offset_x, &offset_y);
+
+  offset_x -= origin_x;
+  offset_y -= origin_y;
+
+  if (offset_x || offset_y)
+    {
+      TIFFSetField (tif, TIFFTAG_XPOSITION, offset_x / xresolution);
+      TIFFSetField (tif, TIFFTAG_YPOSITION, offset_y / yresolution);
+    }
+
+  if (! is_bw &&
+      (drawable_type == GIMP_INDEXED_IMAGE || drawable_type == GIMP_INDEXEDA_IMAGE))
+    TIFFSetField (tif, TIFFTAG_COLORMAP, red, grn, blu);
+
+  /* save path data. we need layer information for that,
+    * so we have to do this in here. :-( */
+  if (page == 0)
+    save_paths (tif, orig_image, cols, rows, offset_x, offset_y);
+
+  /* array to rearrange data */
+  src  = g_new (guchar, bytesperrow * tile_height);
+  data = g_new (guchar, bytesperrow);
+
+  /* Now write the TIFF data. */
+  for (y = 0; y < rows; y = yend)
+    {
+      yend = y + tile_height;
+      yend = MIN (yend, rows);
+
+      gegl_buffer_get (buffer,
+                       GEGL_RECTANGLE (0, y, cols, yend - y), 1.0,
+                       format, src,
+                       GEGL_AUTO_ROWSTRIDE, GEGL_ABYSS_NONE);
+
+      for (row = y; row < yend; row++)
+        {
+          guchar *t = src + bytesperrow * (row - y);
+
+          switch (drawable_type)
+            {
+            case GIMP_INDEXED_IMAGE:
+            case GIMP_INDEXEDA_IMAGE:
+              if (is_bw)
+                {
+                  byte2bit (t, bytesperrow, data, invert);
+                  success = (TIFFWriteScanline (tif, data, row, 0) >= 0);
+                }
+              else
+                {
+                  success = (TIFFWriteScanline (tif, t, row, 0) >= 0);
+                }
+              break;
+
+            case GIMP_GRAY_IMAGE:
+            case GIMP_GRAYA_IMAGE:
+            case GIMP_RGB_IMAGE:
+            case GIMP_RGBA_IMAGE:
+              success = (TIFFWriteScanline (tif, t, row, 0) >= 0);
+              break;
+
+            default:
+              success = FALSE;
+              break;
+            }
+
+          if (! success)
+            {
+              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
+                           _("Failed a scanline write on row %d"), row);
+              goto out;
+            }
+        }
+
+      if ((row % 32) == 0)
+        gimp_progress_update (progress_base + progress_fraction
+                              * (gdouble) row / (gdouble) rows);
+    }
+
+  /* Save GeoTIFF tags to file, if available */
+  if (tsvals->save_geotiff)
+    {
+      GimpParasite *parasite = NULL;
+
+      parasite = gimp_image_get_parasite (image,"Gimp_GeoTIFF_ModelPixelScale");
+
+      if (parasite)
+        {
+          TIFFSetField (tif,
+                        GEOTIFF_MODELPIXELSCALE,
+                        (gimp_parasite_data_size (parasite) / TIFFDataWidth (TIFF_DOUBLE)),
+                        gimp_parasite_data (parasite));
+          gimp_parasite_free (parasite);
+        }
+
+      parasite = gimp_image_get_parasite (image,"Gimp_GeoTIFF_ModelTiePoint");
+      if (parasite)
+        {
+          TIFFSetField (tif,
+                        GEOTIFF_MODELTIEPOINT,
+                        (gimp_parasite_data_size (parasite) / TIFFDataWidth (TIFF_DOUBLE)),
+                        gimp_parasite_data (parasite));
+          gimp_parasite_free (parasite);
+        }
+
+      parasite = gimp_image_get_parasite (image,"Gimp_GeoTIFF_ModelTransformation");
+      if (parasite)
+        {
+          TIFFSetField (tif,
+                        GEOTIFF_MODELTRANSFORMATION,
+                        (gimp_parasite_data_size (parasite) / TIFFDataWidth (TIFF_DOUBLE)),
+                        gimp_parasite_data (parasite));
+          gimp_parasite_free (parasite);
+        }
+
+      parasite = gimp_image_get_parasite (image,"Gimp_GeoTIFF_KeyDirectory");
+      if (parasite)
+        {
+          TIFFSetField (tif,
+                        GEOTIFF_KEYDIRECTORY,
+                        (gimp_parasite_data_size (parasite) / TIFFDataWidth (TIFF_SHORT)),
+                        gimp_parasite_data (parasite));
+          gimp_parasite_free (parasite);
+        }
+
+      parasite = gimp_image_get_parasite (image,"Gimp_GeoTIFF_DoubleParams");
+      if (parasite)
+        {
+          TIFFSetField (tif,
+                        GEOTIFF_DOUBLEPARAMS,
+                        (gimp_parasite_data_size (parasite) / TIFFDataWidth (TIFF_DOUBLE)),
+                        gimp_parasite_data (parasite));
+          gimp_parasite_free (parasite);
+        }
+
+      parasite = gimp_image_get_parasite (image,"Gimp_GeoTIFF_Asciiparams");
+      if (parasite)
+        {
+          TIFFSetField (tif,
+                        GEOTIFF_ASCIIPARAMS,
+                        gimp_parasite_data (parasite));
+          gimp_parasite_free (parasite);
+        }
+    }
+
+  TIFFWriteDirectory (tif);
+
+  gimp_progress_update (progress_base + progress_fraction);
+
+  status = TRUE;
+
+out:
+  if (buffer)
+    g_object_unref (buffer);
+
+  g_free (data);
+  g_free (src);
+  g_free (layer_name);
+
+  return status;
+}
+
+/* FIXME Most of the stuff in save_metadata except the
+ * thumbnail saving should probably be moved to
+ * gimpmetadata.c and gimpmetadata-save.c.
+ */
+static void
+save_metadata (GFile                 *file,
+               TiffSaveVals          *tsvals,
+               gint32                 image,
+               GimpMetadata          *metadata,
+               GimpMetadataSaveFlags  metadata_flags,
+               gint                   saved_bpp)
+{
+  gchar **exif_tags;
+
+  /* See bug 758909: clear TIFFTAG_MIN/MAXSAMPLEVALUE because
+   * exiv2 saves them with wrong type and the original values
+   * could be invalid, see also bug 761823.
+   * we also clear some other tags that were only meaningful
+   * for the original imported image.
+   */
+  static const gchar *exif_tags_to_remove[] =
+  {
+    "Exif.Image.0x0118",  /* MinSampleValue */
+    "Exif.Image.0x0119",  /* MaxSampleValue */
+    "Exif.Image.0x011d",  /* PageName */
+    "Exif.Image.Compression",
+    "Exif.Image.FillOrder",
+    "Exif.Image.InterColorProfile",
+    "Exif.Image.NewSubfileType",
+    "Exif.Image.PageNumber",
+    "Exif.Image.PhotometricInterpretation",
+    "Exif.Image.PlanarConfiguration",
+    "Exif.Image.Predictor",
+    "Exif.Image.RowsPerStrip",
+    "Exif.Image.SampleFormat",
+    "Exif.Image.SamplesPerPixel",
+    "Exif.Image.StripByteCounts",
+    "Exif.Image.StripOffsets"
+  };
+  static const guint n_keys = G_N_ELEMENTS(exif_tags_to_remove);
+
+  for (int k = 0; k < n_keys; k++)
+    {
+      gexiv2_metadata_clear_tag (GEXIV2_METADATA (metadata),
+                                 exif_tags_to_remove[k]);
+    }
+
+  /* get rid of all the EXIF tags for anything but the first sub image. */
+  exif_tags = gexiv2_metadata_get_exif_tags (GEXIV2_METADATA(metadata));
+  for (char **tag = exif_tags; *tag; tag++)
+    {
+      /* Keeping Exif.Image2, 3 can cause exiv2 to save faulty extra TIFF pages
+       * that are empty except for the Exif metadata. See issue #7195. */
+      if (g_str_has_prefix (*tag, "Exif.Image")
+          && (*tag)[strlen ("Exif.Image")] >= '0'
+          && (*tag)[strlen ("Exif.Image")] <= '9')
+        gexiv2_metadata_clear_tag (GEXIV2_METADATA (metadata), *tag);
+      if (g_str_has_prefix (*tag, "Exif.SubImage")
+          && (*tag)[strlen ("Exif.SubImage")] >= '0'
+          && (*tag)[strlen ("Exif.SubImage")] <= '9')
+        gexiv2_metadata_clear_tag (GEXIV2_METADATA (metadata), *tag);
+      if (g_str_has_prefix (*tag, "Exif.Thumbnail"))
+        gexiv2_metadata_clear_tag (GEXIV2_METADATA (metadata), *tag);
+    }
+
+  gimp_metadata_set_bits_per_sample (metadata, saved_bpp);
+
+  if (tsvals->save_exif)
+    metadata_flags |= GIMP_METADATA_SAVE_EXIF;
+  else
+    metadata_flags &= ~GIMP_METADATA_SAVE_EXIF;
+
+  if (tsvals->save_xmp)
+    metadata_flags |= GIMP_METADATA_SAVE_XMP;
+  else
+    metadata_flags &= ~GIMP_METADATA_SAVE_XMP;
+
+  if (tsvals->save_iptc)
+    metadata_flags |= GIMP_METADATA_SAVE_IPTC;
+  else
+    metadata_flags &= ~GIMP_METADATA_SAVE_IPTC;
+
+  if (tsvals->save_thumbnail)
+    metadata_flags |= GIMP_METADATA_SAVE_THUMBNAIL;
+  else
+    metadata_flags &= ~GIMP_METADATA_SAVE_THUMBNAIL;
+
+  if (tsvals->save_profile)
+    metadata_flags |= GIMP_METADATA_SAVE_COLOR_PROFILE;
+  else
+    metadata_flags &= ~GIMP_METADATA_SAVE_COLOR_PROFILE;
+
+  gimp_image_metadata_save_finish (image,
+                                   "image/tiff",
+                                   metadata, metadata_flags,
+                                   file, NULL);
+}
+
+gboolean
+save_image (GFile                  *file,
+            TiffSaveVals           *tsvals,
+            gint32                  image,
+            gint32                  orig_image,    /* the export function */
+                                                   /* might have created  */
+                                                   /* a duplicate         */
+            const gchar            *image_comment,
+            gint                   *saved_bpp,
+            GimpMetadata           *metadata,
+            GimpMetadataSaveFlags   metadata_flags,
+            GError                **error)
+{
+  TIFF     *tif = NULL;
+  gboolean  status              = FALSE;
+  gboolean  out_linear          = FALSE;
+  gint32    num_layers, *layers, current_layer = 0;
+  gint      origin_x = 0, origin_y = 0;
+  gint32    i;
+
+  layers = gimp_image_get_layers (image, &num_layers);
+
+  gimp_progress_init_printf (_("Exporting '%s'"),
+                             gimp_file_get_utf8_name (file));
+
+  /* Open file and write some global data */
+#ifdef TIFF_VERSION_BIG
+  tif = tiff_open (file, (tsvals->bigtiff ? "w8" : "w"), error);
+#else
+  tif = tiff_open (file, "w", error);
+#endif
+
+  if (! tif)
+    {
+      if (! error)
+        g_set_error (error, G_FILE_ERROR, g_file_error_from_errno (errno),
+                     _("Could not open '%s' for writing: %s"),
+                     gimp_file_get_utf8_name (file), g_strerror (errno));
+      goto out;
+    }
+
+  /* The TIFF spec explicitly says ASCII for the image description. */
+  if (image_comment)
+    {
+      const gchar *c = image_comment;
+      gint         len;
+
+      for (len = strlen (c); len; c++, len--)
+        {
+          if ((guchar) *c > 127)
+            {
+              g_message (_("The TIFF format only supports comments in\n"
+                           "7bit ASCII encoding. No comment is saved."));
+              image_comment = NULL;
+
+              break;
+            }
+        }
+    }
+
+  /* do we have a comment?  If so, create a new parasite to hold it,
+   * and attach it to the image. The attach function automatically
+   * detaches a previous incarnation of the parasite. */
+  if (image_comment && *image_comment)
+    {
+      GimpParasite *parasite;
+
+      TIFFSetField (tif, TIFFTAG_IMAGEDESCRIPTION, image_comment);
+      parasite = gimp_parasite_new ("gimp-comment",
+                                    GIMP_PARASITE_PERSISTENT,
+                                    strlen (image_comment) + 1, image_comment);
+      gimp_image_attach_parasite (orig_image, parasite);
+      gimp_parasite_free (parasite);
+    }
+
+#ifdef TIFFTAG_ICCPROFILE
+  if (tsvals->save_profile)
+    {
+      GimpColorProfile *profile;
+      const guint8     *icc_data;
+      gsize             icc_length;
+
+      profile = gimp_image_get_effective_color_profile (orig_image);
+
+      /* Curve of the exported data depends on the saved profile, i.e.
+       * any explicitly-set profile in priority, or the default one for
+       * the storage format as fallback.
+       */
+      out_linear = (gimp_color_profile_is_linear (profile));
+
+      /* Write the profile to the TIFF file. */
+      icc_data = gimp_color_profile_get_icc_profile (profile, &icc_length);
+      TIFFSetField (tif, TIFFTAG_ICCPROFILE, icc_length, icc_data);
+      g_object_unref (profile);
+    }
+#endif
+
+  /* calculate the top-left coordinates */
+  for (i = 0; i < num_layers; i++)
+    {
+      gint offset_x, offset_y;
+
+      gimp_drawable_offsets (layers[i], &offset_x, &offset_y);
+
+      origin_x = MIN (origin_x, offset_x);
+      origin_y = MIN (origin_y, offset_y);
+    }
+
+  /* write last layer as first page. */
+  if (! save_layer (tif,  tsvals, image,
+                    layers[num_layers - current_layer - 1],
+                    current_layer, num_layers, orig_image,
+                    origin_x, origin_y,
+                    saved_bpp, out_linear, error))
+    {
+      goto out;
+    }
+  current_layer++;
+
+  /* close file so we can safely let exiv2 work on it to write metadata.
+   * this can be simplified once multi page TIFF is supported by exiv2
+   */
+  TIFFFlushData (tif);
+  TIFFClose (tif);
+  tif = NULL;
+  if (metadata)
+    save_metadata (file, tsvals, image, metadata, metadata_flags, *saved_bpp);
+
+  /* write the remaining layers */
+  if (num_layers > 1)
+    {
+      tif = tiff_open (file, "a", error);
+
+      if (! tif)
+        {
+          if (! error)
+            g_set_error (error, G_FILE_ERROR,
+                          g_file_error_from_errno (errno),
+                          _("Could not open '%s' for writing: %s"),
+                          gimp_file_get_utf8_name (file),
+                          g_strerror (errno));
+          goto out;
+        }
+
+      for (; current_layer < num_layers; current_layer++)
+        {
+          gint tmp_saved_bpp;
+          if (! save_layer (tif,  tsvals, image,
+                            layers[num_layers - current_layer - 1],
+                            current_layer, num_layers, orig_image,
+                            origin_x, origin_y,
+                            &tmp_saved_bpp, out_linear, error))
+            {
+              goto out;
+            }
+          if (tmp_saved_bpp != *saved_bpp)
+            {
+              /* this should never happen.
+               * if it does, decide if it's really an error.
+               */
+              g_set_error (error, G_FILE_ERROR, G_FILE_ERROR_FAILED,
+                           _("Writing pages with different bit depth "
+                             "is strange."));
+              goto out;
+            }
+          gimp_progress_update ((gdouble) (current_layer + 1) / num_layers);
+        }
+    }
+
+  status = TRUE;
+
+out:
+  /* close the file for good */
+  if (tif)
+    {
+      TIFFFlushData (tif);
+      TIFFClose (tif);
+    }
+
+  gimp_progress_update (1.0);
+
+  return status;
+}
+
+gboolean
+save_dialog (TiffSaveVals  *tsvals,
+             gint32         image,
+             const gchar   *help_id,
+             gboolean       has_alpha,
+             gboolean       is_monochrome,
+             gboolean       is_indexed,
+             gchar        **image_comment,
+             GError       **error,
+             gboolean       classic_tiff_failed)
+{
+  GtkWidget   *dialog;
+  GtkWidget   *vbox;
+  GtkWidget   *frame;
+  GtkWidget   *entry;
+  GtkWidget   *toggle;
+  GtkWidget   *label;
+  GtkWidget   *cmp_g3;
+  GtkWidget   *cmp_g4;
+  GtkWidget   *cmp_jpeg;
+  GtkBuilder  *builder;
+  gchar       *ui_file;
+  gchar      **parasites;
+  gboolean     run;
+  gboolean     has_geotiff = FALSE;
+  gint         n_parasites;
+  gint         i;
+
+  parasites = gimp_image_get_parasite_list (image, &n_parasites);
+  for (i = 0; i < n_parasites; i++)
+    {
+      if (g_str_has_prefix (parasites[i], "Gimp_GeoTIFF_"))
+        {
+          has_geotiff = TRUE;
+          break;
+        }
+    }
+  g_strfreev (parasites);
+
+  dialog = gimp_export_dialog_new (_("TIFF"), PLUG_IN_ROLE, help_id);
+
+  builder = gtk_builder_new ();
+  ui_file = g_build_filename (gimp_data_directory (),
+                              "ui", "plug-ins", "plug-in-file-tiff.ui",
+                              NULL);
+  if (! gtk_builder_add_from_file (builder, ui_file, error))
+    {
+      gchar *display_name = g_filename_display_name (ui_file);
+
+      g_printerr (_("Error loading UI file '%s': %s"),
+                  display_name, error ? (*error)->message : _("Unknown error"));
+
+      g_free (display_name);
+    }
+
+  g_free (ui_file);
+
+  vbox = GTK_WIDGET (gtk_builder_get_object (builder, "tiff_export_vbox"));
+
+  gtk_box_pack_start (GTK_BOX (gimp_export_dialog_get_content_area (dialog)),
+                      vbox, FALSE, FALSE, 0);
+  gtk_widget_show (vbox);
+
+  vbox = GTK_WIDGET (gtk_builder_get_object (builder, "radio_button_box"));
+
+  label = GTK_WIDGET (gtk_builder_get_object (builder, "bigtiff-warning"));
+#ifdef TIFF_VERSION_BIG
+  if (classic_tiff_failed)
+    {
+      gtk_label_set_markup (GTK_LABEL (label),
+                            _("<i>Warning: maximum TIFF file size exceeded.\n Retry as BigTIFF or cancel.</i>"));
+      gtk_label_set_line_wrap (GTK_LABEL (label), TRUE);
+      gtk_label_set_line_wrap_mode (GTK_LABEL (label), PANGO_WRAP_WORD);
+      gtk_label_set_max_width_chars (GTK_LABEL (label), 60);
+    }
+#endif
+  if (! classic_tiff_failed)
+    {
+      gtk_widget_hide (label);
+    }
+
+  frame = gimp_int_radio_group_new (TRUE, _("Compression"),
+                                    G_CALLBACK (gimp_radio_button_update),
+                                    &tsvals->compression, tsvals->compression,
+
+                                    _("_None"),      COMPRESSION_NONE,          NULL,
+                                    _("_LZW"),       COMPRESSION_LZW,           NULL,
+                                    _("_Pack Bits"), COMPRESSION_PACKBITS,      NULL,
+                                    _("_Deflate"),   COMPRESSION_ADOBE_DEFLATE, NULL,
+                                    _("_JPEG"),      COMPRESSION_JPEG,          &cmp_jpeg,
+                                    _("CCITT Group _3 fax"), COMPRESSION_CCITTFAX3, &cmp_g3,
+                                    _("CCITT Group _4 fax"), COMPRESSION_CCITTFAX4, &cmp_g4,
+
+                                    NULL);
+
+  gtk_widget_set_sensitive (cmp_g3, is_monochrome);
+  gtk_widget_set_sensitive (cmp_g4, is_monochrome);
+  gtk_widget_set_sensitive (cmp_jpeg, ! is_indexed);
+
+  if (! is_monochrome)
+    {
+      if (tsvals->compression == COMPRESSION_CCITTFAX3 ||
+          tsvals->compression == COMPRESSION_CCITTFAX4)
+        {
+          gimp_int_radio_group_set_active (GTK_RADIO_BUTTON (cmp_g3),
+                                           COMPRESSION_NONE);
+        }
+    }
+
+  if (is_indexed && tsvals->compression == COMPRESSION_JPEG)
+    {
+      gimp_int_radio_group_set_active (GTK_RADIO_BUTTON (cmp_jpeg),
+                                       COMPRESSION_NONE);
+    }
+
+  gtk_box_pack_start (GTK_BOX (vbox), frame, FALSE, FALSE, 0);
+  gtk_widget_show (frame);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-alpha"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                has_alpha && (tsvals->save_transp_pixels || is_indexed));
+  gtk_widget_set_sensitive (toggle, has_alpha && ! is_indexed);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_transp_pixels);
+
+  entry = GTK_WIDGET (gtk_builder_get_object (builder, "commentfield"));
+  gtk_entry_set_text (GTK_ENTRY (entry), *image_comment ? *image_comment : "");
+
+  g_signal_connect (entry, "changed",
+                    G_CALLBACK (comment_entry_callback),
+                    image_comment);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-exif"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->save_exif);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_exif);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-xmp"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->save_xmp);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_xmp);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-iptc"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->save_iptc);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_iptc);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-geotiff"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                has_geotiff && tsvals->save_geotiff);
+  gtk_widget_set_sensitive (toggle, has_geotiff);;
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_geotiff);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-thumbnail"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->save_thumbnail);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_thumbnail);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-color-profile"));
+#ifdef TIFFTAG_ICCPROFILE
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->save_profile);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_profile);
+#else
+  gtk_widget_hide (toggle);
+#endif
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "bigtiff"));
+#ifdef TIFF_VERSION_BIG
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->bigtiff);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->bigtiff);
+#else
+  gtk_widget_hide (toggle);
+#endif
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "save-layers"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->save_layers);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->save_layers);
+
+  frame = GTK_WIDGET (gtk_builder_get_object (builder, "layers-frame"));
+  g_object_bind_property (toggle, "active",
+                          frame,  "sensitive",
+                          G_BINDING_SYNC_CREATE);
+
+  toggle = GTK_WIDGET (gtk_builder_get_object (builder, "crop-layers"));
+  gtk_toggle_button_set_active (GTK_TOGGLE_BUTTON (toggle),
+                                tsvals->crop_layers);
+  g_signal_connect (toggle, "toggled",
+                    G_CALLBACK (gimp_toggle_button_update),
+                    &tsvals->crop_layers);
+
+  gtk_widget_show (dialog);
+
+  run = (gimp_dialog_run (GIMP_DIALOG (dialog)) == GTK_RESPONSE_OK);
+
+  gtk_widget_destroy (dialog);
+
+  return run;
+}
+
+static void
+comment_entry_callback (GtkWidget  *widget,
+                        gchar     **comment)
+{
+  const gchar *text = gtk_entry_get_text (GTK_ENTRY (widget));
+
+  g_free (*comment);
+  *comment = g_strdup (text);
+}
+
+/* Convert n bytes of 0/1 to a line of bits */
+static void
+byte2bit (const guchar *byteline,
+          gint          width,
+          guchar       *bitline,
+          gboolean      invert)
+{
+  guchar bitval;
+  guchar rest[8];
+
+  while (width >= 8)
+    {
+      bitval = 0;
+      if (*(byteline++)) bitval |= 0x80;
+      if (*(byteline++)) bitval |= 0x40;
+      if (*(byteline++)) bitval |= 0x20;
+      if (*(byteline++)) bitval |= 0x10;
+      if (*(byteline++)) bitval |= 0x08;
+      if (*(byteline++)) bitval |= 0x04;
+      if (*(byteline++)) bitval |= 0x02;
+      if (*(byteline++)) bitval |= 0x01;
+      *(bitline++) = invert ? ~bitval : bitval;
+      width -= 8;
+    }
+
+  if (width > 0)
+    {
+      memset (rest, 0, 8);
+      memcpy (rest, byteline, width);
+      bitval = 0;
+      byteline = rest;
+      if (*(byteline++)) bitval |= 0x80;
+      if (*(byteline++)) bitval |= 0x40;
+      if (*(byteline++)) bitval |= 0x20;
+      if (*(byteline++)) bitval |= 0x10;
+      if (*(byteline++)) bitval |= 0x08;
+      if (*(byteline++)) bitval |= 0x04;
+      if (*(byteline++)) bitval |= 0x02;
+      *bitline = invert ? ~bitval & (0xff << (8 - width)) : bitval;
+    }
+}