PHP Build Validator

<?php session_start ();?>
<?php
{
$authcode = new Authcode ();
if ($authcode->geturifilename () = = "authcode.php")
{
$authcode->outputimg ();
}
}
function Chkauthcode ($Authcode)
{
if ($_session[' authcode '] = = $Authcode)
{
$rtn = true;
}
Else
{
$rtn = false;
}
$_session[' authcode '] = rand (0, 999999);
return $RTN;
}
Class Authcode
{
/* Public Variables * *
* Private Variables * *
var $image;
#
var $sBgcolor;
var $nWidth;
var $nHeight;
var $nLen;
var $bNoise;
var $nNoise;
var $bBorder;
var $aFontlist;
* Constractor * *
function Authcode ()
{
$this->sbgcolor = "#FFCC00";
$this->nwidth = 70;
$this->nheight = 25;
$this->nleftmargin = 5;
$this->nrightmargin = 5;
$this->ntopmargin = 3;
$this->nbottommargin = 2;
$this->nlen = 4;
$this->bnoise = true;
$this->nnoisepoint = 50;
$this->nnoiseline = 5;
$this->bborder = true;

$this->afontlist[0] = "./fonts/arial.ttf";
$this->afontlist[1] = "./fonts/comic.ttf";
$this->afontlist[2] = "./fonts/raavi.ttf";
$this->afontlist[3] = "./fonts/verdanai.ttf";
$this->afontlist[4] = "./fonts/tahoma.ttf";
$this->afontlist[5] = "./fonts/shruti.ttf";
$this->afontlist[6] = "./fonts/bkant. TTF ";
$this->afontlist[7] = "./fonts/comicbd.ttf";
$this->afontlist[8] = "./fonts/courbi.ttf";
$this->afontlist[9] = "./fonts/times.ttf";
}

function outputimg ()
{
$this->image = "";
$this->image = imagecreate ($this->nwidth, $this->nheight);
$back = $this->getcolor ($this->sbgcolor);
Imagefilledrectangle ($this->image, 0, 0, $this->nwidth, $this->nheight, $back);
$size = ($this->nwidth-$this->nleftmargin-$this->nrightmargin)/$this->nlen;
if ($size > ($this->nheight-$this->ntopmargin-$this->nbottommargin))
$size = $this->nheight-$this->ntopmargin-$this->nbottommargin;

$left = ($this->nwidth-$this->nlen* ($size + $size/10))/2 + $this->nleftmargin;
$code = "";
For ($i =0 $i < $this->nlen; $i + +)
{
$randtext = rand (0, 9);
$code. = $randtext;
$textColor = Imagecolorallocate ($this->image, rand (0), rand (0, MB), rand (0, 100));
$font = $this->afontlist[rand (0,9)];//rand (1,4). ". TTF ";
$randsize = rand ($size-$size/10, $size + $size/10);
$location = $left + ($i * $size + $size/10);
Imagettftext ($this->image, $randsize, Rand ( -18,18), $location, Rand ($size, $size + $size/5) + $this->ntopmargin, $ TextColor, $font, $randtext);
}
if ($this->bnoise = = True) $this->setnoise ();
$_session[' authcode ' = $code;
$bordercolor = $this->getcolor ("");
if ($border ==true) imagerectangle ($this->image, 0, 0, $this->nwidth-1, $this->nheight-1, $bordercolor);
Header ("Expires:mon, June June 1997 05:00:00 GMT"); Date in the past
Header ("last-modified:"). Gmdate ("D, D M Y h:i:s"). "GMT"); Always modified
Header ("Cache-control:no-store, No-cache, must-revalidate"); http/1.1
Header ("Cache-control:post-check=0, pre-check=0", false);
Header ("Cache-control:private");
Header ("Pragma:no-cache"); http/1.0
Header ("Content-type:image/png");
Imagepng ($this->image);
Imagedestroy ($this->image);

return $sAuthcode;
}
function Chkauthcode ($Authcode)
{
if ($this->getauthcode () = = $Authcode)
{
$rtn = true;
}
Else
{
$rtn = false;
}
$_session[' authcode '] = rand (0, 999999);
return $RTN;
}
function Getauthcode ()
{
$x _authcode = $_session[' Authcode '];
$_session[' authcode '] = rand (0, 999999);
return $x _authcode;
}

* Private Functions * *
function Geturifilename ()
{
return substr ($_server[' script_name '), Strrpos ($_server[' script_name '], '/') + 1, strlen ($_server[' script_name '])- Strrpos ($_server[' script_name '], '/');
}
function Setnoise ()
{
For ($i =0 $i < $this->nnoiseline; $i + +) {
$randColor = Imagecolorallocate ($this->image, rand (0, 255), rand (0, 255), rand (0, 255));
Imageline ($this->image, rand (0, $this->nwidth), rand (0, $this->nheight), rand (0, $this->nwidth), rand (0, $ this->nheight), $randColor);
}

For ($i =0 $i < $this->nnoisepoint; $i + +) {
$randColor = Imagecolorallocate ($this->image, rand (0, 255), rand (0, 255), rand (0, 255));
Imagesetpixel ($this->image, rand (0, $this->nwidth), rand (0, $this->nheight), $randColor);
}
}
function GetColor ($color)
{
$color = Eregi_replace ("^#", "", $color);
$r = $color [0]. $color [1];
$r = Hexdec ($r);
$b = $color [2]. $color [3];
$b = Hexdec ($b);
$g = $color [4]. $color [5];
$g = Hexdec ($g);
$color = Imagecolorallocate ($this->image, $r, $b, $g);
return $color;
}
}
?>