Linearly interpolate between two table borders.
Source
static TableBorder lerp(TableBorder a, TableBorder 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);
return new TableBorder(
top: BorderSide.lerp(a.top, b.top, t),
right: BorderSide.lerp(a.right, b.right, t),
bottom: BorderSide.lerp(a.bottom, b.bottom, t),
left: BorderSide.lerp(a.left, b.left, t),
horizontalInside: BorderSide.lerp(a.horizontalInside, b.horizontalInside, t),
verticalInside: BorderSide.lerp(a.verticalInside, b.verticalInside, t)
);
}