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);

　　?>