computeHeaderExtent method

double computeHeaderExtent()

Implementation

double computeHeaderExtent() {
  if (header == null) return 0.0;
  assert(header!.hasSize);
  switch (constraints.axis) {
    case Axis.vertical:
      return header!.size.height;
    case Axis.horizontal:
      return header!.size.width;
  }
}