layout method

@override void layout(Context context, BoxConstraints constraints, { bool parentUsesSize = false, })

First widget pass to calculate the children layout and bounding box

Implementation

@override
void layout(Context context, BoxConstraints constraints,
    {bool parentUsesSize = false}) {
  _validateStructure();

  if (children.isEmpty) {
    _context.lastRow = _context.firstRow;
    _layout = null;
    _visible = null;
    box = PdfRect.fromPoints(PdfPoint.zero, constraints.smallest);
    return;
  }

  final resolved = _resolveCachedLayout(context, constraints);
  _validateResolvedLayout(resolved);
  _layout = resolved;
  final visible = _resolveVisibleRows(resolved, constraints);
  _visible = visible;
  _context.lastRow = visible.nextRow;

  _positionVisibleChildren(context, resolved, visible);

  final width = resolved.widths.fold(0.0, (sum, width) => sum + width);
  box = constraints.constrainRect(width: width, height: visible.totalHeight);
}