IMP_Compose::_convertToRelated PHP Method

    protected function _convertToRelated(Horde_Domhtml $html, Horde_Mime_Part $part)
    {
        $r_part = false;
        foreach ($this as $atc) {
            if ($atc->related) {
                $r_part = true;
                break;
            }
        }
        if (!$r_part) {
            return $part;
        }
        /* Create new multipart/related part. */
        $related = new Horde_Mime_Part();
        $related->setType('multipart/related');
        /* Get the CID for the 'root' part. Although by default the first part
         * is the root part (RFC 2387 [3.2]), we may as well be explicit and
         * put the CID in the 'start' parameter. */
        $related->setContentTypeParameter('start', $part->setContentId());
        $related[] = $part;
        /* HTML iteration is from child->parent, so need to gather related
         * parts and add at end after sorting to generate a more sensible
         * attachment list. */
        $add = array();
        foreach ($html as $node) {
            if ($node instanceof DOMElement && $node->hasAttribute(self::RELATED_ATTR)) {
                list($attr_name, $atc_id) = explode(';', $node->getAttribute(self::RELATED_ATTR));
                /* If attachment can't be found, ignore. */
                if ($r_atc = $this[$atc_id]) {
                    if ($r_atc->linked) {
                        $attr = strval($r_atc->link_url);
                    } else {
                        $related_part = $r_atc->getPart(true);
                        $attr = 'cid:' . $related_part->setContentId();
                        $add[] = $related_part;
                    }
                    $node->setAttribute($attr_name, $attr);
                }
                $node->removeAttribute(self::RELATED_ATTR);
            }
        }
        foreach (array_reverse($add) as $val) {
            $related[] = $val;
        }
        return $related;
    }