Base::getPreviewData

public function getPreviewData()
{
	if(!$this->previewId)
	{
		return null;
	}

	if(isset($this->previewData) && $this->previewId == $this->previewData['ID'])
	{
		return $this->previewData;
	}
	$this->previewData = $this->getFileData($this->previewId);

	if(!$this->previewData)
	{
		$fileObject = File::getById($this->fileId);
		if($fileObject)
		{
			$fileObject->changePreviewId(null);
		}
		return array();
	}

	return $this->previewData;
}