captcha returns undefined call to function error

[darkfreaks]

can anyone see the problem here

 

i am running php 5.3 on my server and GD seems to be enabled. and my host said it was probably something to do with the captcha files or script.

 

<?php

session_start();

/*
* File: CaptchaSecurityImages.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 03/08/06
* Updated: 2007-08-12 by Jenny Ferenc (minor visual changes only)
* Requirements: PHP 4/5 with GD and FreeType libraries
* Link: http://www.white-hat-web-design.co.uk/articles/php-captcha.php
* 
* This program is free software; you can redistribute it and/or 
* modify it under the terms of the GNU General Public License 
* as published by the Free Software Foundation; either version 2 
* of the License, or (at your option) any later version.
* 
* This program is distributed in the hope that it will be useful, 
* but WITHOUT ANY WARRANTY; without even the implied warranty of 
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
* GNU General Public License for more details: 
* http://www.gnu.org/licenses/gpl.html
*
*/

class CaptchaSecurityImages {

   var $font = 'VeraSe.ttf';

   function generateCode($characters) {
      /* list all possible characters, similar looking characters and vowels have been removed */
      $possible = '23456789bcdfghjkmnpqrstvwxyz';
      $code = '';
      $i = 0;
      while ($i < $characters) { 
         $code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
         $i++;
      }
      return $code;
   }

   function CaptchaSecurityImages($width=130, $height=40, $characters=6) {

      $code = $this->generateCode($characters);

      // font size will be 60% of the image height
      $font_size = $height * 0.6;
      $image = @imagecreate($width, $height) or die('Cannot initialize new GD image stream');

      // set the colours
      $background_color = imagecolorallocate($image, 255, 255, 255);
      $text_color = imagecolorallocate($image, 20, 40, 100);
      $noise_color = imagecolorallocate($image, 100, 120, 180);

      // generate random dots in background
      for( $i=0; $i<($width*$height)/3; $i++ ) {
         imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
      }

      // generate random lines in background
      for( $i=0; $i<($width*$height)/150; $i++ ) {
         imageline($image, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $noise_color);
      }

      // create textbox and add text
      $textbox = imagettfbbox($font_size, 0, $this->font, $code) or die('Error in imagettfbbox function');
      $x = ($width - $textbox[4])/2;
      $y = ($height - $textbox[5])/2;
      imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code) or die('Error in imagettftext function');

      // output captcha image to browser
      header('Content-Type: image/jpeg');
      imagejpeg($image);
      imagedestroy($image);
      $_SESSION['security_code'] = $code;
   }

}


$captcha = new CaptchaSecurityImages();

?>

this seems to be the problem line here:

 

$textbox = imagettfbbox($font_size, 0, $this->font, $code) or die('Error in imagettfbbox function');
[\code]