基本属性
const OutlineButton({Key key,@required VoidCallback onPressed, // 点击的毁掉VoidCallback onLongPress, // 长按回调ButtonTextTheme textTheme, // 按钮主题Color textColor, // 字体颜色Color disabledTextColor, // 禁用状态的字体颜色Color color, // 背景色Color focusColor, //Color hoverColor,Color highlightColor,Color splashColor, // 水波的颜色。double highlightElevation, // 长按时阴影的高度this.borderSide,this.disabledBorderColor,this.highlightedBorderColor,EdgeInsetsGeometry padding, // 内边框VisualDensity visualDensity, // 视觉密度ShapeBorder shape, // 外观Clip clipBehavior = Clip.none,FocusNode focusNode,bool autofocus = false,Widget child,})

按钮的设置基本用法在【2-6.基本组件【RaisedButton】漂浮按钮】中有讲解。
