groupRows method

void groupRows(int fromRow, int toRow, { bool collapsed = false, })

Groups rows fromRow-toRow (0-based, inclusive) into a collapsible outline. Each call nests one level deeper (Excel's "Group", max 7). When collapsed is true the rows are hidden and the summary row just below the group is flagged collapsed (Excel's default "summary below" layout).

sheet.groupRows(1, 4);                 // collapsible detail rows 2-5
sheet.groupRows(1, 4, collapsed: true); // ...starting collapsed

Implementation

void groupRows(int fromRow, int toRow, {bool collapsed = false}) {
  if (fromRow < 0 || toRow < fromRow) return;
  for (var r = fromRow; r <= toRow; r++) {
    final next = (_rowOutlineLevel[r] ?? 0) + 1;
    _rowOutlineLevel[r] = next > 7 ? 7 : next;
    if (collapsed) _rowHidden.add(r);
  }
  if (collapsed) _rowCollapsed.add(toRow + 1);
}