protected function _doImages_reference_callback($matches)
{
$whole_match = $matches[1];
$alt_text = $matches[2];
$link_id = strtolower($matches[3]);
if ("" == $link_id) {
$link_id = strtolower($alt_text);
# for shortcut links like ![this][].
}
$alt_text = $this->encodeAttribute($alt_text);
if (isset($this->urls[$link_id])) {
$url = $this->encodeAttribute($this->urls[$link_id]);
$result = "<img src=\"{$url}\" alt=\"{$alt_text}\"";
if (isset($this->titles[$link_id])) {
$title = $this->titles[$link_id];
$title = $this->encodeAttribute($title);
$result .= " title=\"{$title}\"";
}
$result .= $this->empty_element_suffix;
$result = $this->hashPart($result);
} else {
# If there's no such link ID, leave intact:
$result = $whole_match;
}
return $result;
}