layoutSpan method

@override SpanSlice? layoutSpan(Context context, BoxConstraints constraints)

Splits a tall table across MultiPage pages, repeating repeat header rows.

Implementation

@override
SpanSlice? layoutSpan(Context context, BoxConstraints constraints) {
  if (children.isEmpty) {
    return SpanSlice(EmptyBox(), null);
  }
  if (!constraints.hasBoundedHeight) {
    return SpanSlice(layout(context, constraints), null);
  }
  final List<TableRow> headers = <TableRow>[
    for (final TableRow row in children)
      if (row.repeat) row,
  ];
  final List<TableRow> body = <TableRow>[
    for (final TableRow row in children)
      if (!row.repeat) row,
  ];
  if (body.isEmpty) {
    return SpanSlice(layout(context, constraints), null);
  }
  final double maxW =
      constraints.hasBoundedWidth ? constraints.maxWidth : 400;
  final List<double> headerH = _rowHeights(context, headers, maxW);
  final List<double> bodyH = _rowHeights(context, body, maxW);
  var chrome = 0.0;
  for (final double h in headerH) {
    chrome += h;
  }
  final double limit = constraints.maxHeight;
  var take = 0;
  var used = chrome;
  for (int i = 0; i < body.length; i++) {
    final double next = used + bodyH[i];
    if (take > 0 && next > limit + 0.5) {
      break;
    }
    used = next;
    take++;
    if (take == 1 && used > limit) {
      break;
    }
  }
  if (take <= 0) {
    take = 1;
  }
  if (take >= body.length) {
    return SpanSlice(layout(context, constraints), null);
  }
  final Table slice = _copyWith(<TableRow>[
    ...headers,
    ...body.take(take),
  ]);
  final Table rest = _copyWith(<TableRow>[
    ...headers,
    ...body.skip(take),
  ]);
  return SpanSlice(
    slice.layout(
      context,
      BoxConstraints(maxWidth: maxW),
    ),
    rest,
  );
}