GD::Barcode::UPCE - Create UPC-E barcode image with GD

  use GD::Barcode::UPCE;
  binmode(STDOUT);
  print "Content-Type: image/png\n\n";
  print GD::Barcode::UPCE->new('123456')->plot->png;

  my $oGdBar = GD::Barcode::UPCE->new('123456789');
  die $GD::Barcode::UPCE::errStr unless($oGdBar);       #Invalid Length

 ex.
  my $oGdB = GD::Barcode::UPCE->new('123456');
  my $oGD = $oGdB->plot(NoText=>1, Height => 20);
  # $sGD is a GD image with Height=>20 pixels, with no text.

 ex.
  my $oGdB = GD::Barcode::UPCE->new('123456');
  my $sPtn = $oGdB->barcode();
  # $sPtn = '';

package GD::Barcode::UPCE;
use strict;
BEGIN { eval{require 'GD.pm';}; };
use GD::Barcode;
require Exporter;
use vars qw($VERSION @ISA $errStr);
@ISA = qw(GD::Barcode Exporter);
$VERSION=1.10;
my $oddEven4UPCE = {
 0 => 'EEEOOO',
 1 => 'EEOEOO',
 2 => 'EEOOEO',
 3 => 'EEOOOE',
 4 => 'EOEEOO',
 5 => 'EOOEEO',
 6 => 'EOOOEE',
 7 => 'EOEOEO',
 8 => 'EOEOOE',
 9 => 'EOOEOE'
};
my $leftOddBar ={
 '0' => '0001101',
 '1' => '0011001',
 '2' => '0010011',
 '3' => '0111101',
 '4' => '0100011',
 '5' => '0110001',
 '6' => '0101111',
 '7' => '0111011',
 '8' => '0110111',
 '9' => '0001011'
};
my $leftEvenBar = {
 '0' => '0100111',
 '1' => '0110011',
 '2' => '0011011',
 '3' => '0100001',
 '4' => '0011101',
 '5' => '0111001',
 '6' => '0000101',
 '7' => '0010001',
 '8' => '0001001',
 '9' => '0010111'
};
my $guardBar = 'G0G';
my $UPCrightGuardBar = '0G0G0G';
#------------------------------------------------------------------------------
# new (for Spreadsheet::ParseExcel)
#------------------------------------------------------------------------------
sub new($$) {
  my($sClass, $sTxt) = @_;
  $errStr ='';
  my $oThis = {};
  bless $oThis;
  return undef if($errStr = $oThis->init($sTxt));
  return $oThis;
}
#------------------------------------------------------------------------------
# init (for Spreadsheet::ParseExcel)
#------------------------------------------------------------------------------
sub init($$){
        my($oThis, $sTxt) =@_;
        return 'Invalid characters' if($sTxt =~ /[^0-9]/); 

#Check
    my $iLen = length($sTxt);
        if( $iLen == 6 ) {
                $sTxt = '0' . $sTxt;
        $sTxt .= calcUPCECD( $sTxt );
        }
        elsif($iLen == 7) {
        $sTxt .= calcUPCECD( $sTxt );
        }
        elsif($iLen == 8) {
                ;
        }
        else {
                return 'Invalid Length';
        }
        $oThis->{text} = $sTxt;
        return '';
}
#------------------------------------------------------------------------------
# calcUPCACD (for GD::Barcode::UPCE)
#------------------------------------------------------------------------------
sub calcUPCACD {
  my( $sTxt ) = @_;
  my( $i, $iSum, @aWeight);

  @aWeight = (3,1,3,1,3,1,3,1,3,1,3);
  $iSum = 0;
  for( $i = 0; $i < 11; $i++ ) {
      $iSum += substr($sTxt, $i, 1)  * $aWeight[$i];
  }
  $iSum %= 10;
  $iSum = ($iSum == 0)? 0: (10 - $iSum);
  return "$iSum";
}
#------------------------------------------------------------------------------
# calcUPCECD (for GD::Barcode::UPCE)
#------------------------------------------------------------------------------
sub calcUPCECD {
  my( $sTxt ) =@_;
  my( $upcA );

  my $cLast = substr($sTxt, 6, 1);
  if ($cLast =~ /[0-2]/) {      #0,1,2
        $upcA = substr($sTxt, 0, 3). $cLast . '0' x 4 . substr($sTxt, 3, 3);
  }
  elsif ($cLast eq '3') {
        $upcA = substr($sTxt, 0, 4) . '0' x 5 . substr($sTxt, 4, 2);
  }
  elsif ($cLast eq '4') {
        $upcA = substr($sTxt, 0, 5) . '0' x 5 . substr($sTxt, 5, 1);
  }
  else  { # $cLast =~ /5-9/
        $upcA = substr($sTxt, 0, 6) . '0' x 4 . $cLast;
  }
  return &calcUPCACD( $upcA );
}
#------------------------------------------------------------------------------
# barcode (for GD::Barcode::UPCE)
#------------------------------------------------------------------------------
sub barcode($) {
  my ($oThis) = @_;
  my ($topDigit, $oddEven, $c, $i);
  my ($sRes);

#(1)Init
  my $sTxt = $oThis->{text};
  $sRes = $guardBar;            #GUARD
  $oddEven = $oddEven4UPCE->{substr($sTxt, 7, 1)};

#(2)Left 6 (Skip 1 character)
    for( $i = 1; $i < 7; $i++ ){
        $c = substr($sTxt, $i, 1);
                $sRes .= GD::Barcode::barPtn($c, 
                                ( substr($oddEven, $i-1, 1) eq 'O' )?
                                                $leftOddBar : $leftEvenBar);
    }
#
  $sRes .= $UPCrightGuardBar;
  return $sRes;

}
#------------------------------------------------------------------------------
# plot (for Spreadsheet::ParseExcel)
#------------------------------------------------------------------------------
sub plot($%) {
  my($oThis, %hParam) =@_;
  my $sTxt = $oThis->{text};
  my $sPtn = $oThis->barcode();

#Create Image
  my $iHeight = ($hParam{Height})? $hParam{Height} : 50;
  my ($oGd, $cBlack);
  if($hParam{NoText}) {
        ($oGd, $cBlack) = GD::Barcode::plot($sPtn, length($sPtn), $iHeight, 0, 0);
  }
  else {
        my($fW,$fH) = (GD::Font->Small->width, GD::Font->Small->height);
        my $iWidth = length($sPtn)+ 2*($fW+1);
        #Bar Image
        ($oGd, $cBlack) = GD::Barcode::plot($sPtn, $iWidth, $iHeight, $fH, $fW+1);
        #String
        $oGd->string(GD::Font->Small,        0, $iHeight - $fH, substr($sTxt, 0, 1), $cBlack);
        $oGd->string(GD::Font->Small, $fW +  8, $iHeight - $fH, substr($sTxt, 1, 6), $cBlack);
        $oGd->string(GD::Font->Small, $fW + 54, $iHeight - $fH, substr($sTxt, 7, 1), $cBlack);
  }
  return $oGd;

  return $oGd;
}
1;
__END__