method lerp

Source

static BoxDecoration lerp(BoxDecoration a, BoxDecoration b, double t) {
  if (a == null && b == null)
    return null;
  if (a == null)
    return b.scale(t);
  if (b == null)
    return a.scale(1.0 - t);
  // TODO(abarth): lerp ALL the fields.
  return new BoxDecoration(
    backgroundColor: Color.lerp(a.backgroundColor, b.backgroundColor, t),
    backgroundImage: b.backgroundImage,
    border: Border.lerp(a.border, b.border, t),
    borderRadius: BorderRadius.lerp(a.borderRadius, b.borderRadius, t),
    boxShadow: BoxShadow.lerpList(a.boxShadow, b.boxShadow, t),
    gradient: b.gradient,
    shape: b.shape
  );
}