truncate method
Truncates the string to maxLength characters.
If the string is longer than maxLength, it is cut and ellipsis
(default '...') is appended. The returned string's total length
will not exceed maxLength.
Implementation
String truncate(int maxLength, {String ellipsis = '...'}) {
if (length <= maxLength) return this;
final cutoff = maxLength - ellipsis.length;
if (cutoff <= 0) return ellipsis.substring(0, maxLength);
return '${substring(0, cutoff)}$ellipsis';
}