/**
  * Given an associative array of old Id strings and new Id strings.
  * Update any of the old Ids that this plugin instance recognizes to their
  * new value.
  * 
  * @param array $idMap An associative array of old id-strings to new id-strings.
  * @return void
  * @access public
  * @since 1/24/08
  */
 public function replaceIds(array $idMap)
 {
     // Update the media-file mapping
     if (strlen(trim($this->getContent()))) {
         $this->setContent(MediaFile::getMappedIdString($idMap, $this->getContent()));
         unset($this->_mediaFile);
     }
     // Update any ids in the description HTML.
     $this->setRawDescription($this->replaceIdsInHtml($idMap, $this->getRawDescription()));
 }