BorderDirectional constructor

const BorderDirectional({BorderSide top: BorderSide.none, BorderSide start: BorderSide.none, BorderSide end: BorderSide.none, BorderSide bottom: BorderSide.none })

Creates a border.

The start and end sides represent the horizontal sides; the start side is on the leading edge given the reading direction, and the end side is on the trailing edge. They are resolved during paint.

All the sides of the border default to BorderSide.none.

The arguments must not be null.

Implementation 

const BorderDirectional({
  this.top = BorderSide.none,
  this.start = BorderSide.none,
  this.end = BorderSide.none,
  this.bottom = BorderSide.none,
}) : assert(top != null),
     assert(start != null),
     assert(end != null),
     assert(bottom != null);