class.captcha.php

<?php
/*********************************************************************
    class.captcha.php

    Very basic captcha class.

    Peter Rotich <peter@osticket.com>
    Copyright (c)  2006-2013 osTicket
    http://www.osticket.com

    Released under the GNU General Public License WITHOUT ANY WARRANTY.
    See LICENSE.TXT for details.

    vim: expandtab sw=4 ts=4 sts=4:
**********************************************************************/
class Captcha {
    var $hash;
    var $bgimages=array('cottoncandy.png','grass.png','ripple.png','silk.png','whirlpool.png',
                        'bubbles.png','crackle.png','lines.png','sand.png','snakeskin.png');
    var $font = 10;
    function __construct($len=6,$font=7,$bg=''){

        $this->hash = strtoupper(substr(md5(rand(0, 9999)),rand(0, 24),$len));
        $this->font = $font;

        if($bg && !is_dir($bg)){ //bg file provided?
            $this->bgimg=$bg;
        }else{ //assume dir provided or defaults to local.
            $this->bgimg=rtrim($bg,'/').'/'.$this->bgimages[array_rand($this->bgimages, 1)];
        }
    }

    function getImage(){

        if(!extension_loaded('gd') || !function_exists('gd_info')) //GD ext required.
            return;

        $_SESSION['captcha'] =''; //Clear

        list($w,$h) = getimagesize($this->bgimg);
        $x = round(($w/2)-((strlen($this->hash)*imagefontwidth($this->font))/2), 1);
        $y = round(($h/2)-(imagefontheight($this->font)/2));

        $img= imagecreatefrompng($this->bgimg);
        imagestring($img,$this->font, $x, $y,$this->hash,imagecolorallocate($img,0, 0, 0));

        header("Content-Type: image/png");
        imagepng($img);
        imagedestroy($img);
        $_SESSION['captcha'] = md5($this->hash);
    }
}

?>