1 <?php defined('SYSPATH') OR die('No direct access allowed.');
3 * Captcha driver for "alpha" style.
5 * $Id: Alpha.php 4367 2009-05-27 21:23:57Z samsoir $
9 * @copyright (c) 2007-2008 Kohana Team
10 * @license http://kohanaphp.com/license.html
12 class Captcha_Alpha_Driver extends Captcha_Driver {
15 * Generates a new Captcha challenge.
17 * @return string the challenge answer
19 public function generate_challenge()
21 // Complexity setting is used as character count
22 return text::random('distinct', max(1, Captcha::$config['complexity']));
26 * Outputs the Captcha image.
28 * @param boolean html output
31 public function render($html)
33 // Creates $this->image
34 $this->image_create(Captcha::$config['background']);
36 // Add a random gradient
37 if (empty(Captcha::$config['background']))
39 $color1 = imagecolorallocate($this->image, mt_rand(0, 100), mt_rand(0, 100), mt_rand(0, 100));
40 $color2 = imagecolorallocate($this->image, mt_rand(0, 100), mt_rand(0, 100), mt_rand(0, 100));
41 $this->image_gradient($color1, $color2);
44 // Add a few random circles
45 for ($i = 0, $count = mt_rand(10, Captcha::$config['complexity'] * 3); $i < $count; $i++)
47 $color = imagecolorallocatealpha($this->image, mt_rand(0, 255), mt_rand(0, 255), mt_rand(0, 255), mt_rand(80, 120));
48 $size = mt_rand(5, Captcha::$config['height'] / 3);
49 imagefilledellipse($this->image, mt_rand(0, Captcha::$config['width']), mt_rand(0, Captcha::$config['height']), $size, $size, $color);
52 // Calculate character font-size and spacing
53 $default_size = min(Captcha::$config['width'], Captcha::$config['height'] * 2) / strlen($this->response);
54 $spacing = (int) (Captcha::$config['width'] * 0.9 / strlen($this->response));
56 // Background alphabetic character attributes
57 $color_limit = mt_rand(96, 160);
58 $chars = 'ABEFGJKLPQRTVY';
60 // Draw each Captcha character with varying attributes
61 for ($i = 0, $strlen = strlen($this->response); $i < $strlen; $i++)
63 // Use different fonts if available
64 $font = Captcha::$config['fontpath'].Captcha::$config['fonts'][array_rand(Captcha::$config['fonts'])];
66 $angle = mt_rand(-40, 20);
67 // Scale the character size on image height
68 $size = $default_size / 10 * mt_rand(8, 12);
69 $box = imageftbbox($size, $angle, $font, $this->response[$i]);
71 // Calculate character starting coordinates
72 $x = $spacing / 4 + $i * $spacing;
73 $y = Captcha::$config['height'] / 2 + ($box[2] - $box[5]) / 4;
75 // Draw captcha text character
76 // Allocate random color, size and rotation attributes to text
77 $color = imagecolorallocate($this->image, mt_rand(150, 255), mt_rand(200, 255), mt_rand(0, 255));
79 // Write text character to image
80 imagefttext($this->image, $size, $angle, $x, $y, $color, $font, $this->response[$i]);
82 // Draw "ghost" alphabetic character
83 $text_color = imagecolorallocatealpha($this->image, mt_rand($color_limit + 8, 255), mt_rand($color_limit + 8, 255), mt_rand($color_limit + 8, 255), mt_rand(70, 120));
84 $char = $chars[mt_rand(0, 14)];
85 imagettftext($this->image, $size * 2, mt_rand(-45, 45), ($x - (mt_rand(5, 10))), ($y + (mt_rand(5, 10))), $text_color, $font, $char);
89 return $this->image_render($html);
92 } // End Captcha Alpha Driver Class