EdgeInsets lerp(EdgeInsets a, EdgeInsets b, double t)

Linearly interpolate between two EdgeInsets.

If either is null, this function interpolates from EdgeInsets.zero.

Source 

static EdgeInsets lerp(EdgeInsets a, EdgeInsets b, double t) {
  if (a == null && b == null)
    return null;
  if (a == null)
    return b * t;
  if (b == null)
    return a * (1.0 - t);
  return new EdgeInsets.fromLTRB(
    ui.lerpDouble(a.left, b.left, t),
    ui.lerpDouble(a.top, b.top, t),
    ui.lerpDouble(a.right, b.right, t),
    ui.lerpDouble(a.bottom, b.bottom, t)
  );
}