<?php
  include '../../lib/functions.php';
  
  // must start or continue session and save CAPTCHA string in $\_SESSION\; for\; it$
  // to be available to other requests
  if (!isset(_SESSION))
  {
      session_start();
      header('Cache-control: private');
  }
  
  // create a 65x20 pixel image
  $width\; =\; 65;$height = 20;
  $image\; =\; imagecreate(65,\; 20);$// fill the image background color
  bg_color = imagecolorallocate($image,\; 0x33,\; 0x66,\; 0xFF);\; imagefilledrectangle($image, 0, 0, $width,$height, $bg\_color);$// fetch random text
  text = random_text(5);
  
  // determine x and y coordinates for centering text
  $font\; =\; 5;$x = imagesx($image)\; /\; 2\; -\; strlen($text) * imagefontwidth($font)\; /\; 2;$y = imagesy($image)\; /\; 2\; -\; imagefontheight($font) / 2;
  
  // write text on image
  $fg\_color\; =\; imagecolorallocate($image, 0xFF, 0xFF, 0xFF);
  imagestring($image,$font, $x,$y, $text,$fg_color);
  
  // save the CAPTCHA string for later comparison
  $\_SESSION[\text{'}captcha\text{'}]\; =$text;
  
  // output the image
  header('Content-type: image/png');
  imagepng($image);\; imagedestroy($image);
  ?>