<?php
/**
 * @version        Somao_Search X1.0 9:23 2012-1-1 Somao $
 * @package        Somao_Search.Site
 * @copyright      Copyright (c) 2009 - 2012, Somao, Inc.
 * @license        http://www.somao123.com/
 * @link           http://www.somao.cc/
**/
session_save_path(dirname(__FILE__)."/../data/sessions/");
session_start();
Header("Content-type: image/gif");
/*
* 初始化
*/
$border = 0; //是否要边框 1要:0不要
$how = 4; //验证码位数
$w = $how*15; //图片宽度
$h = 20; //图片高度
$fontsize = 5; //字体大小
//字体
$alpha = "abcdefghijkmnopqrstuvwxyz"; //验证码内容1:字母
$number = "023456789"; //验证码内容2:数字
$randcode = ""; //验证码字符串初始化
srand((double)microtime()*1000000); //初始化随机数种子

$im = ImageCreate($w, $h); //创建验证图片

/*
* 绘制基本框架
*/
$bgcolor = ImageColorAllocate($im, 255, 255, 255); //设置背景颜色
ImageFill($im, 0, 0, $bgcolor); //填充背景色
if($border)
{
    $black = ImageColorAllocate($im, 0, 0, 0); //设置边框颜色
    ImageRectangle($im, 0, 0, $w-1, $h-1, $black);//绘制边框
}

/*
* 逐位产生随机字符
*/
for($i=0; $i<$how; $i++)
{   
    $alpha_or_number = mt_rand(0, 1); //字母还是数字
    $str = $alpha_or_number ? $alpha : $number;
    $which = mt_rand(0, strlen($str)-1); //取哪个字符
    $code = substr($str, $which, 1); //取字符
    $j = !$i ? 4 : $j+15; //绘字符位置
    $color3 = ImageColorAllocate($im, mt_rand(0,100), mt_rand(0,100), mt_rand(0,100)); //字符随即颜色
    ImageChar($im, $fontsize, $j, 3, $code, $color3); //绘字符
    $randcode .= $code; //逐位加入验证码字符串
}

/*
* 添加干扰
*/
for($i=0; $i<1; $i++)//绘背景干扰线
{   
    $color1 = ImageColorAllocate($im, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255)); //干扰线颜色
    ImageArc($im, mt_rand(-5,$w), mt_rand(-5,$h), mt_rand(20,300), mt_rand(20,200), 55, 44, $color1); //干扰线
}   
for($i=0; $i<$how*5; $i++)//绘背景干扰点
{   
    $color2 = ImageColorAllocate($im, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255)); //干扰点颜色 
    ImageSetPixel($im, mt_rand(0,$w), mt_rand(0,$h), $color2); //干扰点
}

//把验证码字符串写入session

$_SESSION['randcode'] = $randcode;

/*绘图结束*/
Imagegif($im);
ImageDestroy($im);
/*绘图结束*/
?> 
