#!/bin/sh -
#
# xbm2gif [-t] files...
#
#   This uses the pbmplus package to convert the xpm files to GIF format
#
# If transparency (-t) flag is given, the white color in X bitmaps and the
# transparent color of X pixmaps, is first converted into a grey color (as
# used in WWW clients) and then this color is set as the transparent color
# inside the GIF image.  This make the Bitmap or Pixmap appropriate for
# direct use on a WWW server in a form which is usable by the maximum
# number of web clients including those which do not understand the
# transparent GIF extension.
# 
# If the transparency flag is not given the transparent color is converted
# into the `white' by default by the PbmPlus utilities.
#
# The script also checks X Pixmaps for the "None" color before actually
# applying the transparancy (-t) option. This stops some Web Clients
# mis-interperting the GIF transparency on other `close' grey shades in the
# image.
#
# NOTE: created files are placed in the current directory, not the
# directory of the source X Bitmap/Pixmap file. This is a feature
# exploited by other scripts to convert whole directories of gif files
# into a completely different directory (the current).
# 
#  Anthony Thyssen         12 Feburary 1995     anthony@cit.gu.edu.au
#
# -------

TRANS=
if [ "X$1" = "X-t" ]; then
  TRANS="#BFBFBF"  # the transparent color to use.
  shift
fi

exec 9>&1

for i in "$@" ; do

  if [ ! -r $i ]; then
    echo >&2 "Unable to read \"$i\""
    continue
  fi

  echo >&9 "converting \"$i\""

  name="`expr "//$i" : '.*/\([^/]*\)'`"               # remove path
  suffix="`expr "$name" : '.*\.\([^.]*\)$'`"   # extract last suffix 
  name="`expr "$name" : '\(.*\)\.[^.]*$'`"     # remove last suffix

  case "$suffix" in
    xbm)  # ------ X Bitmap ------
      if [ "$TRANS" ]; then
        # Make white (background) transparent
        sed 's/unsigned //' "$i" | xbmtopbm |\
          pnmdepth 255 2>/dev/null | pgmtoppm "$TRANS" |\
          ppmtogif -transparent "$TRANS" 2>&1  1>"$name.gif"
      else
        # just plain conversion
        sed 's/unsigned //' "$i" | xbmtopbm | ppmtogif 2>&1  1>"$name.gif"
      fi
      ;;
    xpm)  # ------- X Pixmap ------
      if [ $TRANS ] && grep 'c  *[Nn]one' "$i" >/dev/null; then
        # Make "None" color transparent
        sed "s/c  *[Nn]one/c $TRANS/g" "$i" | x2p.sed |\
          xpmtoppm | pnmdepth 255 2>/dev/null |\
              ppmtogif -transparent "$TRANS" 2>&1  1>"$name.gif"
      else
        # just plain conversion
        x2p.sed "$i" | xpmtoppm | pnmdepth 255 2>/dev/null |\
              ppmtogif 2>&1  1>"$name.gif"
      fi 
      ;;
    *)
      echo >&2 "Unknown suffix for \"$i\"."
      continue
      ;;
  esac

  if [ ! -s "$name.gif" ]; then
    rm -f "$name.gif"
    echo >&2 "Failed to convert \"$i\""
  fi

done | egrep -v '(computing colormap|colors found)' >&2