htmlpurifier/library/HTMLPurifier/AttrDef/HTML/Length.php

<?php

/**
 * Validates the HTML type length (not to be confused with CSS's length).
 * 
 * This accepts integer pixels or percentages as lengths for certain
 * HTML attributes.
 */

class HTMLPurifier_AttrDef_HTML_Length extends HTMLPurifier_AttrDef_HTML_Pixels
{
    
    public function validate($string, $config, $context) {
        
        $string = trim($string);
        if ($string === '') return false;
        
        $parent_result = parent::validate($string, $config, $context);
        if ($parent_result !== false) return $parent_result;
        
        $length = strlen($string);
        $last_char = $string[$length - 1];
        
        if ($last_char !== '%') return false;
        
        $points = substr($string, 0, $length - 1);
        
        if (!is_numeric($points)) return false;
        
        $points = (int) $points;
        
        if ($points < 0) return '0%';
        if ($points > 100) return '100%';
        
        return ((string) $points) . '%';
        
    }
    
}