border buttom fluter code example
Example: A circuler border button in flutter
Padding( padding: EdgeInsets.only(left: 150.0, right: 0.0), child: RaisedButton( textColor: Colors.white, color: Colors.black, child: Text("Search"), onPressed: () {}, shape: new RoundedRectangleBorder( borderRadius: new BorderRadius.circular(30.0), ), ),)