<?php
/*
* File: CaptchaSecurityImages.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 03/08/06
* Updated: 07/02/07
* 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
*
*/

session_start();

class CaptchaSecurityImages {
  var $font = 'mytype.ttf';
  var $ans = 0;
  function generateCode($max_a = 9, $max_b = 9, $max_c = 9) {
    $code = '';
    $a = rand(1, $max_a);
    $b = rand(1, $max_b);
    $c = rand(1, $max_c);
    $operator = array('', '');
    switch(rand(1, 3)){
      case 1 :
        $operator[0] = '+';
        switch(rand(1, 3)){
          case 1: $operator[1] = '+'; $this->ans = $a + $b + $c; break;
          case 2: $operator[1] = '-'; $this->ans = $a + $b - $c; break;
          case 3: $operator[1] = 'x'; $this->ans = $a + $b * $c; break;
        }
        break;
      case 2 :
        $operator[0] = '-';
        switch(rand(1, 3)){
          case 1: $operator[1] = '+'; $this->ans = $a - $b + $c; break;
          case 2: $operator[1] = '-'; $this->ans = $a - $b - $c; break;
          case 3: $operator[1] = 'x'; $this->ans = $a - $b * $c; break;
        }
        break;
      case 3 :
        $operator[0] = 'x';
        switch(rand(1, 3)){
          case 1: $operator[1] = '+'; $this->ans = $a * $b + $c; break;
          case 2: $operator[1] = '-'; $this->ans = $a * $b - $c; break;
          case 3: $operator[1] = 'x'; $this->ans = $a * $b * $c; break;
        }
        break;
    }
    $code = $a . $operator[0] . $b . $operator[1] . $c;
    /* show the answer => $code = $a . $operator[0] . $b . $operator[1] . $c; . '=' . $this->ans; */
    unset($a, $b, $c, $operator);
    return $code;
  }

  function CaptchaSecurityImages($width = 110, $height = 40, $characters = 5) {
    $code = $this->generateCode();
    /* font size will be 55% 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)/8; $i++ ) {
      imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
    }
    /* generate random lines in background */
    for( $i=0; $i<($width*$height)/450; $i++ ) {
      imageline($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_code1'] = $this->ans;
  }
}
$captcha = new CaptchaSecurityImages();
unset($captcha);
?>