Method canPreview

public static function canPreview($fileName)
{
    $fileExt = PhocaDownloadFile::getExtension($fileName);
    switch ($fileExt) {
        case 'pdf':
        case 'jpeg':
        case 'jpg':
        case 'png':
        case 'gif':
            return true;
            break;
        default:
            return false;
            break;
    }
    return false;
}