BorderRadius borderRadius

The border radius of the rounded corners.

Values are clamped so that horizontal and vertical radii sums do not exceed width/height.

This value is ignored if clipper is non-null.

Source 

BorderRadius get borderRadius => _borderRadius;
void borderRadius=(BorderRadius value)

Source 

set borderRadius (BorderRadius value) {
  assert(value != null);
  if (_borderRadius == value)
    return;
  _borderRadius = value;
  _markNeedsClip();
}