outer method
Compute an outer border radius from a given margin
Implementation
BorderRadius outer(EdgeInsets margin) {
return BorderRadius.only(
topLeft: Radius.elliptical(
topLeft.x + margin.left / 2,
topLeft.y + margin.top / 2,
),
topRight: Radius.elliptical(
topRight.x + margin.right / 2,
topRight.y + margin.top / 2,
),
bottomRight: Radius.elliptical(
bottomRight.x + margin.right / 2,
bottomRight.y + margin.bottom / 2,
),
bottomLeft: Radius.elliptical(
bottomLeft.x + margin.left / 2,
bottomLeft.y + margin.bottom / 2,
),
);
}