<?php
/*******************************************************************\
 * Exchangerix v2.0
 * http://www.exchangerix.com
 *
 * Copyright (c) 2018 Exchangerix Software. All rights reserved.
 * ---------- Exchangerix IS NOT FREE SOFTWARE ----------
\*******************************************************************/

	session_start();

	// Captcha Settings
	$image_width = 110;
	$image_height = 35;
	$characters_on_image = 6;
	$font = './inc/futura.ttf';
	$font_size = 18;
	$possible_letters = '23456789bcdfghkmnpqrsvwxyz'; // the characters that can be used in the CAPTCHA code
	$random_dots = 11;
	$random_lines = 10;
	$captcha_text_color = "0x00000";
	$captcha_noice_color = "0x142864";
	$bg = trim($_GET['bg']);

	$code = '';

	$i = 0;
	while ($i < $characters_on_image)
	{ 
		$code .= substr($possible_letters, mt_rand(0, strlen($possible_letters)-1), 1);
		$i++;
	}

	$image = @imagecreate($image_width, $image_height);

	/* setting the background, text and noise colours here */
	if (!$bg || $bg == "grey")
		$background_color = imagecolorallocate($image, 249, 249, 249);
	else
		$background_color = imagecolorallocate($image, 255, 255, 255);

	$arr_text_color = hexrgb($captcha_text_color);
	$text_color = imagecolorallocate($image, $arr_text_color['red'], $arr_text_color['green'], $arr_text_color['blue']);

	$arr_noice_color = hexrgb($captcha_noice_color);
	$image_noise_color = imagecolorallocate($image, $arr_noice_color['red'], $arr_noice_color['green'], $arr_noice_color['blue']);

	/* generating the dots randomly in background */
	for( $i=0; $i<$random_dots; $i++ )
	{
		imagefilledellipse($image, mt_rand(0,$image_width), mt_rand(0,$image_height), 2, 3, $image_noise_color);
	}

	/* generating lines randomly in background of image */
	for( $i=0; $i<$random_lines; $i++ )
	{
		imageline($image, mt_rand(0,$image_width), mt_rand(0,$image_height), mt_rand(0,$image_width), mt_rand(0,$image_height), $image_noise_color);
	}

	/* create a text box and add 6 letters code in it */
	$textbox = imagettfbbox($font_size, 0, $font, $code); 
	$x = ($image_width - $textbox[4])/2;
	$y = ($image_height - $textbox[5])/2;
	imagettftext($image, $font_size, 0, $x, $y, $text_color, $font , $code);

	/* Show captcha image in the page html page */
	header('Content-Type: image/jpeg'); // defining the image type to be shown in browser widow
	imagejpeg($image); //showing the image
	imagedestroy($image); //destroying the image instance
	$_SESSION['captcha'] = $code;

	function hexrgb ($hexstr)
	{
	  $int = hexdec($hexstr);

	  return array("red" => 0xFF & ($int >> 0x10),
				   "green" => 0xFF & ($int >> 0x8),
				   "blue" => 0xFF & $int);
	}

?>