/**
* Returns one of three things: a full URL to a thumbnail preview of the record
* if an image is available in an external system; an array of parameters to
* send to VuFind's internal cover generator if no fixed URL exists; or false
* if no thumbnail can be generated.
*
* @param string $size Size of thumbnail (small, medium or large -- small is
* default).
*
* @return string|array|bool
*/
public function getThumbnail($size = 'small')
{
$params = parent::getThumbnail($size);
// Support thumbnails embedded in the Summon record when no unique identifier
// is found... (We don't use them in cases where we have an identifier, since
// we want to allow these to be passed to configured external services).
if (!isset($params['oclc']) && !isset($params['issn']) && !isset($params['isbn']) && !isset($params['upc'])) {
if ($size === 'small' && isset($this->fields['thumbnail_s'][0])) {
return ['proxy' => $this->fields['thumbnail_s'][0]];
} else {
if (isset($this->fields['thumbnail_m'][0])) {
return ['proxy' => $this->fields['thumbnail_m'][0]];
}
}
}
$formats = $this->getFormats();
if (!empty($formats)) {
$params['contenttype'] = $formats[0];
}
return $params;
}