<?php

function UPCAbarcode($code) {
$lw = 2; $hi = 100;
$Lencode = array('0001101','0011001','0010011','0111101','0100011',
'0110001','0101111','0111011','0110111','0001011');
$Rencode = array('1110010','1100110','1101100','1000010','1011100',
'1001110','1010000','1000100','1001000','1110100');
$ends = '101'; $center = '01010';

if ( strlen($code) != 11 ) { die("UPC-A Must be 11 digits."); }

$ncode = '0'.$code;
$even = 0; $odd = 0;
for ($x=0;$x<12;$x++) {
if ($x % 2) { $odd += $ncode[$x]; } else { $even += $ncode[$x]; }
}
$code.=(10 - (($odd * 3 + $even) % 10)) % 10;

$bars=$ends;
$bars.=$Lencode[$code[0]];
for($x=1;$x<6;$x++) {
$bars.=$Lencode[$code[$x]];
}
$bars.=$center;
for($x=6;$x<12;$x++) {
$bars.=$Rencode[$code[$x]];
}
$bars.=$ends;

$img = ImageCreate($lw*95+30,$hi+30);
$fg = ImageColorAllocate($img, 0, 0, 0);
$bg = ImageColorAllocate($img, 255, 255, 255);
ImageFilledRectangle($img, 0, 0, $lw*95+30, $hi+30, $bg);
$shift=10;
for ($x=0;$x<strlen($bars);$x++) {
if (($x<10) || ($x>=45 && $x<50) || ($x >=85)) { $sh=10; } else { $sh=0; }
if ($bars[$x] == '1') { $color = $fg; } else { $color = $bg; }
ImageFilledRectangle($img, ($x*$lw)+15,5,($x+1)*$lw+14,$hi+5+$sh,$color);
}

ImageString($img,4,5,$hi-5,$code[0],$fg);
for ($x=0;$x<5;$x++) {
ImageString($img,5,$lw*(13+$x*6)+15,$hi+5,$code[$x+1],$fg);
ImageString($img,5,$lw*(53+$x*6)+15,$hi+5,$code[$x+6],$fg);
}
ImageString($img,4,$lw*95+17,$hi-5,$code[11],$fg);

header("Content-Type: image/png");
ImagePNG($img);
}

UPCAbarcode('12345678901');

?>