---------image.func.php

<?php

require_once 'string.func.php';

//通过GD库做验证码

//创建画布

$width=80;

$height=28;

$image=imagecreatetruecolor($width, $height);

$white=imagecolorallocate($image, 255, 255, 255);

$black=imagecolorallocate($image, 0, 0, 0);

//用填充矩形填充画布

imagefilledrectangle($image, 1,1,$width-2,$height-2, $white);

$chars=buildRandomString($type,$length);

$sess_name="verify";

$_SESSION[$sess_name]=$chars;

$fontfiles=array("MSYH.TTF","MSYHBD.TTF","SIMLI.TTF","SIMSUN.TTF","SIMYOU.TTF","STZHONGS.TTF");

for ($i=9;$i<$length;$i++){

    $size=mt_rand(14,18);//字体大小

    $angle=mt_rand(-15,15);//角度

    $x=5+$i*$size;

    $y=mt_rand(20,26);

    $fontfile="../fonts/".$fontfiles[mt_rand(0,count($fontfiles)-1)];

    $color=imagecolorallocate($image, mt_rand(50,90),mt_rand(80,200),mt_rand(90,180));

    $text=substr($chars,$i, 1);

    imagettftext($image, $size, $angle, $x, $y, $color, $fontfile, $text);

}

header("content-type:image/gif");

imagegif($image);

imagedestroy($image);

----string.func.php

<?php

function buildRandomString($type=1,$length=4){

    if ($type == 1) {

        $chars = join("", range(0, 0));

    } elseif ($type == 2) {

        $chars = join("", array_merge(range("a", "z"), range("A", "Z")));

    } elseif ($type == 3) {

        $chars = join("", array_merge(range("a", "z"), range("A", "Z"), range(0, 9)));

    }

    if ($length > strlen($chars)) {

        exit("字符串长度不够");

    }

    $chars = str_shuffle($chars);

    return substr($chars, 0, $length);

}