computeHeaderExtent method

double computeHeaderExtent()

Implementation

double computeHeaderExtent() {
  if (_headerSize != null) {
    return switch (constraints.axis) {
      Axis.vertical => _headerSize!.height,
      Axis.horizontal => _headerSize!.width,
    };
  } else {
    assert(headerChild.hasSize);
    return switch (constraints.axis) {
      Axis.vertical => headerChild.size.height,
      Axis.horizontal => headerChild.size.width,
    };
  }
}