#  The line above is intentionally blank
#+
#  Name:
#     ndf2gif
 
#  Purpose:
#     Converts an NDF into a GIF file.
 
#  Type of Module:
#     Bourne shell script
 
#  Usage:
#     ndf2gif in [out]

#  Description:
#     This Bourne shell script converts an NDF into a 256 grey-level
#     Graphics Interchange Format (GIF) file.  One- or two-dimensional
#     images can be handled.  The script uses the CONVERT utility
#     NDF2TIFF to produce a TIFF file and then various PBMPLUS utilities
#     to convert the TIFF file into a GIF file.
#
#     Error messages are converted into Starlink style (preceded by !).
 
#  Parameters:
#     IN = NDF (Read)
#        The name of the input NDF (without the .sdf extension).
#     OUT = FILENAME (Write)
#        The name of the GIF file to be generated (without the .gif 
#        extension which is appended).  If this is omitted, the value of
#        the IN parameter is used.
 
#  Examples:
#     ndf2gif old new
#        This converts the NDF called old (in file old.sdf)
#        into a GIF file new.gif.
#     ndf2gif horse
#        This converts the NDF called horse (in file old.sdf)
#        into a GIF file horse.gif.

#  Notes:
#     -  This initial version of the script handles only 256 grey 
#     levels and does not use the image colour lookup table so
#     absolute data values may be lost.
#
#     -  The PBMPLUS utilities tifftopnm and ppmtogif must be available
#     on your PATH.

#     -  At the time of writing, this utility uses a special Netpbm version
#     of tifftopnm on alpha OSF/1 due to a problem with tifftopnm in the
#     standard release of PBMPLUS.  Netpbm is based on PBMPLUS but
#     contains many improvements and additions.

#  Related Applications:
#     CONVERT: GIF2NDF
 
#  Authors:
#     MJC: Malcolm J. Currie (STARLINK)
#     GJP: G.J. Privett (Starlink - UWCC)
#     AJC: A.J. Chipperfield (Starlink - RAL)
#     {enter_new_authors_here}
 
#  History:
#     1995 March 2 (MJC):
#        Original conversion.
#     1995 October 24 (GJP):
#        Added prologue and revised to avoid using KAPPA.
#     1995 November 13 (AJC):
#        Added default output file, and error reporting and exit at each
#        stage.
#     1997 July 15 (MJC):
#        Used a special tifftopnm for alpha_OSF1.
#     1997 October 3 (MJC):
#        Improved the parameter handling to allow for no arguments, and
#        to remove any .sdf that may be present in the first argument.
#        Fixed bug that gave incorrect extraction of the base name.
 
#-

# Check that a file name was given.
if [ "$#" -eq 0 ]
then
   echo "!! NDF2GIF: no NDF name supplied"
   echo "!  Usage: ndf2gif in [out]"
   exit
fi

# Remove any .sdf file extension.
root=`echo $1 | sed 's#.sdf##'`

# Find the filename less any path.
name=`basename $root`

# Set required output file name.  Defaults to the input name.
out=${2:-$name}

# Determine whether the operating system is alpha_OSF1 or not.
machine=`uname -m`
opsys=`uname`

# Use NDF2TIFF to create a TIFF file.  Only the DATA component is 
# propagated.

$CONVERT_DIR/ndf2tiff in=$root out=convert_temp_$name \
  </dev/null  2>&1 | \
  sed 's/^\!\!/\! /' | \
  awk \
'BEGIN{err=0}\
/^\!/{if(err==0){err=1;print "!! NDF2GIF: Error reports from NDF2TIFF"}};\
{print};\
END{if(err==1){exit 1}}' || \
  (rm -f convert_temp_$name.tif
   echo "!  NDF2GIF: Abandoned at NDF2TIFF"
   exit 1
  ) || exit 1

# Use PBMPLUS tools to convert the TIFF file to a GIF image (except
# use the Netpbm version of tifftopnm on alpha_OSF1 because of a bug
# in the released PBMPLUS version).
if test "$machine" = "alpha" -a  "$opsys" = "OSF1"
then
   $CONVERT_DIR/tifftopnm convert_temp_$name.tif 2> convert_err1_$name.lis | \
     ppmtogif 2> convert_err2_$name.lis > ${out}.gif || \
     { sed 's/^/!  NDF2GIF:/' convert_err?_$name.lis 1>&2
       rm -f convert_err?_$name.lis convert_temp_$name.tif
       exit 1
     }

else
   tifftopnm convert_temp_$name.tif 2> convert_err1_$name.lis | \
     ppmtogif 2> convert_err2_$name.lis > ${out}.gif || \
     { sed 's/^/!  NDF2GIF:/' convert_err?_$name.lis 1>&2
       rm -f convert_err?_$name.lis convert_temp_$name.tif
       exit 1
     }
fi
  rm -f convert_err?_$name.lis 
  rm -f convert_temp_$name.tif