用PHP实现登陆验证码(类似条行码状)

<?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''; $center = ''01010'';
/* UPC-A Must be 11 digits, we compute the checksum. */
if ( strlen($code) != 11 ) { die("UPC-A Must be 11 digits."); }
/* Compute the EAN-13 Checksum digit */
$ncode = ''0''.$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;
/* Create the bar encoding using a binary string */
$bars=$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;
/* Generate the Barcode Image */
$img = ImageCreate($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,$color);
}
/* Add the Human Readable Label */
ImageString($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],$fg);
/* Output the Header and Content. */
header("Content-Type: image/png");
ImagePNG($img);
}

UPCAbarcode(''12345678901'');

?>

原文转自：http://www.ltesting.net