In this example we will see how to refresh captcha image in php gd.
In this example we will see how to refresh captcha image in php gd.<?php
session_start();
if(isset($_POST['submit_x']) && isset($_POST['submit_y'])) {
if(!empty($_POST['name']) && !empty($_POST['message'])) {
$data = base64_decode($_SESSION['captcha_image_code']);
$captcha_image = imagecreatefromstring($data);
$x = $_POST['submit_x'];
$y = $_POST['submit_y'];
$rgb = imagecolorat($captcha_image, $x, $y);
$color_tran = imagecolorsforindex($captcha_image, $rgb);
$captcha_ok = ($color_tran['red'] == 255 && $color_tran['green'] == 0 && $color_tran['blue'] == 0 && $color_tran['alpha'] == 0) ;
if($captcha_ok) {
$result = "Thanks for submitting your comment.";
}
} else {
$result = "Please fill out the form.";
}
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Captcha</title>
</head>
<body>
<?php if(!empty($result)) echo "<div style='color:#990000; margin-bottom: 20px;'>" . $result . "</div>"; ?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post" enctype="multipart/form-data">
<p>Name<br/><input type="text" name="name" /></p>
<p>Message<br/><textarea name="message"></textarea></p>
<p>
Click the captcha to get another security code:<br/>
<input type='image' name='submit' src='captcha.php' alt='Captcha Security Image' />
</p>
</form>
</body>
</html>
This page is saved as index.php
captcha.php
<?php
session_start();
class CaptchaSecurityImages {
var $font = 'C:/WINNT/Fonts/arial.ttf';
function generateCode($characters) {
$possible = '23456789bcdfghjkmnpqrstvwxyz';
$code = '';
$i = 0;
while ($i < $characters) {
$code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);
$i++;
}
return $code;
}
function CaptchaSecurityImages($width='320',$height='40',$characters='6') {
$code = $this->generateCode($characters);
$font_size = $height * 0.75;
$image = imagecreate($width, $height) or die('Cannot initialize new GD image stream');
$background_color = imagecolorallocate($image, 255, 255, 255);
$text_color = imagecolorallocate($image, 20, 40, 100);
$noise_color = imagecolorallocate($image, 100, 120, 180);
for( $i=0; $i<($width*$height)/3; $i++ ) {
imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);
}
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);
}
$textbox = imagettfbbox($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 , $code) or die('Error in imagettftext function');
header('Content-Type: image/jpeg');
imagejpeg($image);
imagedestroy($image);
$_SESSION['security_code'] = $code;
}
}
$width = isset($_GET['width']) && $_GET['width'] < 600 ? $_GET['width'] : '120';
$height = isset($_GET['height']) && $_GET['height'] < 200 ? $_GET['height'] : '40';
$characters = isset($_GET['characters']) && $_GET['characters'] > 2 ? $_GET['characters'] : '6';
$captcha = new CaptchaSecurityImages($width,$height,$characters);
?>
After running the program you will get the following output