<?php
if (!defined('BASEPATH'))
    exit('No direct script access allowed');
class Captcha_code  
{  
    var $width='60';  
    var $num='4';  
    var $height='20';  
    var $name='randcode';  
  
    public function __construct($conf="")  
    {  
        if($conf!="")  
        {  
            foreach($conf as $key=>$value)  
            {  
                $this->$key=$value;  
            }  
        }  
    }  
      
    function show()  
    {  
        Header("Content-type: image/gif");  
        /*  
        * 初始化  
        */  
        $border = 0; //是否要边框 1要:0不要  
        $how = $this->num; //验证码位数  
        $w = $this->width; //图片宽度  
        $h = $this->height; //图片高度  
        $fontsize = 5; //字体大小  
        $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<5; $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*15; $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  
          
        //$this->session->set_userdata(array($this->name=>$randcode));  
        session_start();  
        $_SESSION[$this->name]=$randcode;  
        
        /*绘图结束*/  
        Imagegif($im);  
        ImageDestroy($im);  
        /*绘图结束*/  
    }  
}  