lerp method

@override BoxDecoration? lerp(double t)

Returns the value this variable has at the given animation clock value.

The default implementation of this method uses the +, -, and * operators on T. The begin and end properties must therefore be non-null by the time this method is called.

In general, however, it is possible for this to return null, especially when t=0.0 and begin is null, or t=1.0 and end is null.

Implementation

@override
BoxDecoration? lerp(double t) {
  if (begin == null && end == null) return null;
  if (begin == null) return end!.scale(t);
  if (end == null) return begin!.scale(1.0 - t);
  if (t == 0.0) return begin;
  if (t == 1.0) return end;
  return BoxDecoration(
    color: Color.lerp(begin!.color, end!.color, t),
    gradient: lerpGradientWithColor(
        begin!.gradient, end!.gradient, begin!.color, end!.color, t),
    image: t < 0.5
        ? begin!.image
        : end!.image, // TODO(ianh): cross-fade the image
    border: BoxBorder.lerp(begin!.border, end!.border, t),
    borderRadius:
        BorderRadiusGeometry.lerp(begin!.borderRadius, end!.borderRadius, t),
    boxShadow: BoxShadow.lerpList(begin!.boxShadow, end!.boxShadow, t),

    shape: t < 0.5 ? begin!.shape : end!.shape,
  );
}