<?php class HTMLPurifier_AttrDef_CSS_AlphaValue extends HTMLPurifier_AttrDef_CSS_Number { public function __construct() { parent::__construct(false); // opacity is non-negative, but we will clamp it } public function validate($number, $config, $context) { $result = parent::validate($number, $config, $context); if ($result === false) return $result; $float = (float) $result; if ($float < 0.0) $result = '0'; if ($float > 1.0) $result = '1'; return $result; } }