[% PERL %]
  # Get the incoming values
  my @types = @{$stash->get('types')};
  my @colors = @{$stash->get('colors')};
  my %defaults = %{$stash->get('defaults')};

  # Get the form input provided by the TT2Params directive
  my %params = %{$stash->get('params')};

  my %hex;

  foreach my $type (@types) {

    my $flag = 0;

    foreach my $color (@colors) {
      my $value = $params{$type . $color};
      $flag++ unless ($value =~ /^\d+$/ and $value >= 0 and $value < 256);
    }

    if ($flag) {
      # The user supplied an unacceptable value,
      # so use the default.
      $hex{$type} = $defaults{$type};
    }
    else {
      # User values were ok.
      my @rgb;
      foreach my $color (@colors) {
        push @rgb, $params{$type . $color};
      }
      $hex{$type} = sprintf("%02X%02X%02X", @rgb);
    }
  }

  $stash->set(hex => \%hex);

[% END %]

[% INCLUDE form.html %]