Генериране на картинка за визуално потвърждение

Ето как можем да сложим визуално потвърждение в форма за регистрация или нещо подобно 🙂

Имаме файл с фонт-а на картинката – http://uptime.data.bg/monofont.ttf

и 2 php файлa

1вия image.php ( задължително вашия php сървър трябва да поддържа GD, иначе няма да можете да генерирате никаква картинка ! )

<?php
session_start();

/*
* File: image.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 03/08/06
* 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 = 'monofont.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($width='120',$height='40',$characters='6') {
$code = $this->generateCode($characters);
/* font size will be 75% of the image height */
$font_size = $height * 0.75;
$image = @imagecreate($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);
$x = ($width - $textbox[4])/2;
$y = ($height - $textbox[5])/2;
imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code);
/* output captcha image to browser */
imagejpeg($image);
imagedestroy($image);
$_SESSION['security_code'] = $code;
}

}

$width = isset($_GET['width']) ? $_GET['width'] : '120';
$height = isset($_GET['height']) ? $_GET['height'] : '40';
$characters = isset($_GET['characters']) ? $_GET['characters'] : '6';

header('Content-Type: image/jpeg');
$captcha = new CaptchaSecurityImages($width,$height,$characters);

?>

2рия (формата)

form.php

<?php
session_start();

if( isset($_POST['submit'])) {
if(($_SESSION['security_code'] == $_POST['security_code']) && (!empty($_SESSION['security_code'])) ) {
// Insert you code for processing the form here
echo 'Thank you. Your message said "'.$_POST['message'].'"';
} else {
// Insert your code for showing an error message here
echo 'Sorry, you have provided an invalid security code';
}
} else {
?>

<form action="form.php" method="post">
Message: <input type="text" name="message" /><br />
<img src="image.php?width=100&height=40&character=5" /><br />
Security Code: <input id="security_code" name="security_code" type="text" /><br />
<input type="submit" name="submit" value="Submit" />
</form>


<?php
}
?>