parseCellId function
Parses a cell ID (format: "${rowId}_${columnId}") into its components.
Implementation
(double rowId, int columnId) parseCellId(String cellId) {
final idx = cellId.lastIndexOf('_');
return (
double.parse(cellId.substring(0, idx)),
int.parse(cellId.substring(idx + 1)),
);
}