PHPePub\Core\Structure\NCX\NavPoint::finalizeEPub3 PHP Method

    function finalizeEPub3(&$nav = "", &$playOrder = 0, $level = 0, $subLevelClass = null, $subLevelHidden = false)
    {
        $maxLevel = $level;
        if ($this->id == null) {
            $this->id = "navpoint-" . $playOrder;
        }
        $dir = "";
        if (isset($this->writingDirection)) {
            $dir .= " dir=\"" . $this->writingDirection . "\"";
        }
        $indent = str_repeat("\t", $level) . "\t\t\t\t";
        $nav .= $indent . "<li id=\"" . $this->id . "\"" . $dir . ">\n";
        if (isset($this->contentSrc)) {
            $nav .= $indent . "\t<a href=\"" . $this->contentSrc . "\"" . $dir . ">" . $this->label . "</a>\n";
        } else {
            $nav .= $indent . "\t<span" . $dir . ">" . $this->label . "</span>\n";
        }
        if (sizeof($this->navPoints) > 0) {
            $maxLevel++;
            $nav .= $indent . "\t<ol epub:type=\"list\"" . $dir;
            if (isset($subLevelClass)) {
                $nav .= " class=\"" . $subLevelClass . "\"";
            }
            if ($subLevelHidden) {
                $nav .= " hidden=\"hidden\"";
            }
            $nav .= ">\n";
            foreach ($this->navPoints as $navPoint) {
                /** @var $navPoint NavPoint */
                $retLevel = $navPoint->finalizeEPub3($nav, $playOrder, $level + 2, $subLevelClass, $subLevelHidden);
                if ($retLevel > $maxLevel) {
                    $maxLevel = $retLevel;
                }
            }
            $nav .= $indent . "\t</ol>\n";
        }
        $nav .= $indent . "</li>\n";
        return $maxLevel;
    }