roundedS method

ContainerBuilder roundedS(
  1. double radius
)

rounded-s -> 设置开始方向的圆角（LTR 时为 left，RTL 时为 right）

Implementation

ContainerBuilder roundedS(double radius) {
  if (_borderRadius == null) {
    _borderRadius = BorderRadiusDirectional.only(
      topStart: Radius.circular(radius),
      bottomStart: Radius.circular(radius),
    );
  } else if (_borderRadius is BorderRadiusDirectional) {
    final existing = _borderRadius as BorderRadiusDirectional;
    _borderRadius = BorderRadiusDirectional.only(
      topStart: Radius.circular(radius),
      topEnd: existing.topEnd,
      bottomStart: Radius.circular(radius),
      bottomEnd: existing.bottomEnd,
    );
  } else if (_borderRadius is BorderRadius) {
    // 如果之前使用的是 BorderRadius，转换为 BorderRadiusDirectional
    final existing = _borderRadius as BorderRadius;
    _borderRadius = BorderRadiusDirectional.only(
      topStart: Radius.circular(radius),
      topEnd: existing.topRight,
      bottomStart: Radius.circular(radius),
      bottomEnd: existing.bottomRight,
    );
  }
  return this;
}