<?php

/**
 * @filename MY_captcha_helper.php 
 * @encoding UTF-8 
 * @author 邱伟平 
 * @copyright 连云港龙泽商务有限公司 
 * @datetime 2014-5-15  15:33:16
 * @version 1.0
 * @Description
 */
function captcha($width = 100, $height = 20, $num = 4) {


    $CI = & get_instance();
    $CI->load->library('session');

    //Header("Content-type: image/gif");
    /*
     * 初始化
     */
    $border = 0; //是否要边框 1要:0不要
    $how = $num; //验证码位数
    $w = $width; //图片宽度
    $h = $height; //图片高度
    $fontsize = 5; //字体大小
//    $alpha = "abcdefghijkmnpqrstuvwxyz"; //验证码内容1:字母
    $alpha = "123456789"; //全数字
    
    $number = "123456789"; //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 * 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
//    }

    //$_SESSION[$this->name]=$randcode;
    $CI->session->set_userdata('captcha_code', $randcode);
    //ob_clean();
    /* 绘图结束 */
    Imagegif($im);
    ImageDestroy($im);
    /* 绘图结束 */
}

/* End of file : MY_captcha_helper.php */
