![\"\"](\"https:\/\/www.matteoiammarrone.com\/public\/images\/captcha.png\")
<\/p>\nQuante volte avreste voluto avere un bellissimo e professionale codice antispam nei vostri scripts in php?<\/p>\n
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Ecco a voi come fare.<\/span><\/p>\n Svilupperemo una classe e useremo le librerie gd del nostro fidato linguaggio.<\/span><\/p>\n 1 ) Create una pagina di nome antispam.php<\/strong><\/p>\n <\/strong><\/p>\n <\/strong> session_start(); \/\/Avviamo la sessione<\/span><\/p>\n class CaptchaSecurityImages { \/\/Creazione della classe<\/span><\/p>\n <\/span><\/span>var $font = ’monofont.ttf’;<\/span><\/p>\n <\/span><\/span>function generateCode($characters) {<\/span><\/p>\n <\/span><\/span>\/* list all possible characters, similar looking characters and vowels have been removed *\/<\/span><\/p>\n <\/span><\/span>$possible = ’23456789bcdfghjkmnpqrstvwxyz’;<\/span><\/p>\n <\/span><\/span>$code = ”;<\/span><\/p>\n <\/span><\/span>$i = 0;<\/span><\/p>\n <\/span><\/span>while ($i < $characters) { <\/span><\/p>\n <\/span><\/span>$code .= substr($possible, mt_rand(0, strlen($possible)-1), 1);<\/span><\/p>\n <\/span><\/span>$i++;<\/span><\/p>\n <\/span><\/span>}<\/span><\/p>\n <\/span><\/span>return $code;<\/span><\/p>\n <\/span><\/span>}<\/span><\/p>\n <\/span><\/span>function CaptchaSecurityImages($width=’120′,$height=’40’,$characters=’6′) {<\/span><\/p>\n <\/span><\/span>$code = $this->generateCode($characters);<\/span><\/p>\n <\/span><\/span>\/* font size will be 75% of the image height *\/<\/span><\/p>\n <\/span><\/span>$font_size = $height * 0.75;<\/span><\/p>\n <\/span><\/span>$image = @imagecreate($width, $height) or die(’Le librerie gd non sono installate nel tuo php’);<\/span><\/p>\n <\/span><\/span>\/* set the colours *\/<\/span><\/p>\n <\/span><\/span>$background_color = imagecolorallocate($image, 255, 255, 255);<\/span><\/p>\n <\/span><\/span>$text_color = imagecolorallocate($image, 20, 40, 100);<\/span><\/p>\n <\/span><\/span>$noise_color = imagecolorallocate($image, 100, 120, 180);<\/span><\/p>\n <\/span><\/span>\/* generate random dots in background *\/<\/span><\/p>\n <\/span><\/span>for( $i=0; $i<($width*$height)\/3; $i++ ) {<\/span><\/p>\n <\/span><\/span>imagefilledellipse($image, mt_rand(0,$width), mt_rand(0,$height), 1, 1, $noise_color);<\/span><\/p>\n <\/span><\/span>}<\/span><\/p>\n <\/span><\/span>\/* generate random lines in background *\/<\/span><\/p>\n <\/span><\/span>for( $i=0; $i<($width*$height)\/150; $i++ ) {<\/span><\/p>\n <\/span><\/span>imageline($image, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $noise_color);<\/span><\/p>\n <\/span><\/span>}<\/span><\/p>\n <\/span><\/span>\/* create textbox and add text *\/<\/span><\/p>\n <\/span><\/span>$textbox = imagettfbbox($font_size, 0, $this->font, $code) or die(’Error in imagettfbbox function’);<\/span><\/p>\n <\/span><\/span>$x = ($width – $textbox[4])\/2;<\/span><\/p>\n <\/span><\/span>$y = ($height – $textbox[5])\/2;<\/span><\/p>\n <\/span><\/span>imagettftext($image, $font_size, 0, $x, $y, $text_color, $this->font , $code) or die(’Error in imagettftext function’);<\/span><\/p>\n <\/span><\/span>\/* output captcha image to browser *\/<\/span><\/p>\n <\/span><\/span>header(’Content-Type: image\/jpeg’);<\/span><\/p>\n <\/span><\/span>imagejpeg($image);<\/span><\/p>\n <\/span><\/span>imagedestroy($image);<\/span><\/p>\n <\/span><\/span>$_SESSION[’security_code’] = $code;<\/span><\/p>\n <\/span><\/span>}<\/span><\/p>\n }<\/span><\/p>\n $width = isset($_GET[’width’]) ? $_GET[’width’] : ’120’;<\/span><\/p>\n $height = isset($_GET[’height’]) ? $_GET[’height’] : ’40’;<\/span><\/p>\n $characters = isset($_GET[’characters’]) && $_GET[’characters’] > 1 ? $_GET[’characters’] : ’6’;<\/span><\/p>\n $captcha = new CaptchaSecurityImages($width,$height,$characters); \/\/Stampiamo la classe<\/span><\/p>\n
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