BoxDecoration scale(double factor)

Returns a new box decoration that is scaled by the given factor.

Source 

BoxDecoration scale(double factor) {
  // TODO(abarth): Scale ALL the things.
  return new BoxDecoration(
    backgroundColor: Color.lerp(null, backgroundColor, factor),
    backgroundImage: backgroundImage,
    border: Border.lerp(null, border, factor),
    borderRadius: BorderRadius.lerp(null, borderRadius, factor),
    boxShadow: BoxShadow.lerpList(null, boxShadow, factor),
    gradient: gradient,
    shape: shape
  );
}