flatbutton border flutter

new OutlineButton(
  child: new Text("Button text"),
  onPressed: null,
  shape: new RoundedRectangleBorder(borderRadius: new BorderRadius.circular(30.0))
)

OutlinedButton(
  child: Text('Woolha.com'),
  style: OutlinedButton.styleFrom(
    primary: Colors.white,
    backgroundColor: Colors.teal,
    shape: const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(10))),
  ),
)

// It Does Possible!
FlatButton(
          shape: RoundedRectangleBorder(side: BorderSide(
            color: Colors.blue,
            width: 1,
            style: BorderStyle.solid
          ),
          borderRadius: BorderRadius.circular(50)),
          onPressed: null,
          child: Text('Button', style: TextStyle(color: Colors.blue)
          ),
          textColor: MyColor.white,
        )

shape: RoundedRectangleBorder(
  borderRadius: BorderRadius.circular(18.0),
  side: BorderSide(color: Colors.red)
),