package Image::DS9::Constants;

use strict;
use warnings;

require constant;
require Exporter;

our @ISA = qw( Exporter );

our @EXPORT;

our @values = 
  (
   (map { 'wcs' . $_ } ('a'..'z')),
   (
    'about',
    'abs',
    'active',
    'align',
    'all',
    'amplifier',
    'append',
    'array',
    'automatic',
    'average',
    'background',
    'black',
    'blink',
    'blue',
    'boxcar',
    'buffersize',
    'buttons',
    'center',
    'clear',
    'colorbar',
    'cols',
    'column',
    'command',
    'copy',
    'coordinate',
    'coordformat',
    'crosshair',
    'cyan',
    'datasec',
    'degrees',
    'delete',
    'deleteall',
    'delim',
    'depth',
    'destination',
    'detector',
    'dss',
    'dss2blue',
    'dss2red',
    'ecliptic',
    'eso',
    'examine',
    'exclude',
    'factor',
    'file',
    'filename',
    'filter',
    'first',
    'fits',
    'fk4',
    'fk5',
    'format',
    'function',
    'galactic',
    'gap',
    'gaussian',
    'global',
    'green',
    'grid',
    'gz',
    'hide',
    'horzgraph',
    'icrs',
    'image',
    'include',
    'info',
    'invert',
    'interpolate',
    'interval',
    'jpeg',
    'last',
    'layout',
    'level',
    'limits',
    'linear',
    'load',
    'local',
    'log',
    'magenta',
    'magnifier',
    'manual',
    'minmax',
    'mode',
    'mosaic',
    'mosaicimage',
    'mosaicimages',
    'moveback',
    'movefront',
    'name',
    'new',
    'next',
    'nl',
    'no',
    'off',
    'on',
    'orientation',
    'page',
    'pagescale',
    'pagesize',
    'palette',
    'pan',
    'panner',
    'paste',
    'physical',
    'png',
    'pointer',
    'ppm',
    'prev',
    'pros',
    'radius',
    'red',
    'refresh',
    'rel',
    'replace',
    'resample',
    'reset',
    'resolution',
    'rotate',
    'row',
    'sao',
    'saoimage',
    'saotng',
    'save',
    'scope',
    'selectall',
    'selected',
    'selectnone',
    'semicolon',
    'server',
    'setup',
    'sexagesimal',
    'show',
    'single',
    'size',
    'sky',
    'skyformat',
    'smooth',
    'source',
    'sqrt',
    'squared',
    'state',
    'strip',
    'stsci',
    'sum',
    'survey',
    'system',
    'tiff',
    'tile',
    'to',
    'to fit',
    'tofit',
    'type',
    'url',
    'user',
    'value',
    'vertgraph',
    'wcs',
    'white',
    'x',
    'xy',
    'y',
    'yellow',
    'yes',
    'zoom',
    'zscale',
   )
  );


sub import
{
  @EXPORT = &gen_list; # we want it to muck about with @_;

  __PACKAGE__->export_to_level(1, @_ );
}

sub list
{
  # need to add extra arg to front to make gen_list happy

  unshift @_, __PACKAGE__ ;
  my @list = sort &gen_list;
  no strict 'refs';
  my $len = 0;
  do { my $l = length($_); $len = $l if $l > $len } foreach @list;
  printf("%-${len}s => '%s'\n", $_, &$_) foreach @list;
    
}


sub gen_list
{
  my $pfx = '_';

  if ( @_ > 1 && $_[1] eq 'Prefix' )
  {
    (undef, $pfx ) = splice( @_, 1, 2 );
  }

  my @list;

  for my $value ( @values )
  {
    (my $name = $value) =~ s/\W/_/g;
    $name = $pfx . $name;
    constant->import( $name, $value );
    push @list, $name;
  }

  @list;
}


1;


__END__

=head1 NAME

  Image::DS9::Constants - predefined constants

=head1 SYNOPSIS

  # import all of the constants
  use Image::DS9::Constants;

  # import a subset
  use Image::DS9::Constants qw( _const1 _const2 );

  # change the prefix
  use Image::DS9::Constants Prefix => 'X_';

  # change the prefix and import a subset
  use Image::DS9::Constants 
     Prefix => 'X_', qw( X_const1 X_const2 );

  # list the available constants;
  use Image::DS9::Constants;
  Image::DS9::Constants::list;
  Image::DS9::Constants::list( Prefix => 'X_' );

=head1 DESCRIPTION

This module provides a large number of Perl constants for option strings used
to communicate with B<DS9>.  The constants have a default prefix of C<_>,
which may be changed by the user (see L</SYNOPSIS>).  See the documentation
for the Perl B<constant> module for information on what constitutes a legal
constant name (for instance, two leading underscores are not allowed).

To determine what the constants are, use the B<list> function:

  perl -MImage::DS9::Constants \
          -e 'Image::DS9::Constants::list'

This will print a listing of all of the constants.  To specify a different
prefix,

  perl -MImage::DS9::Constants \
          -e 'Image::DS9::Constants::list( Prefix => "XX")'


=head1 LICENSE

This software is released under the GNU General Public License.  You
may find a copy at 

   http://www.fsf.org/copyleft/gpl.html

=head1 AUTHOR

Diab Jerius ( djerius@cfa.harvard.edu )

=head1 SEE ALSO

  perl(1), Image::DS9;

=cut