Flutter--局部组件状态更新

先看一个系统组件

    StatefulBuilder(builder: (BuildContext context, StateSetter setState) {
      return TextButton(onPressed: () => setState((){}), child: Text("刷新"));
    });

​​​​​​​自定义组件

//Flutter决定是否更新组件主要是判断该组件是否为dirty，setState其实就是将组建标记为dirty的过程，可以直接用该组件的的context将组件标记。

class StateBuilder extends StatelessWidget {

  final Widget Function(BuildContext context, void Function() rebuild)builder;

  const StateBuilder(this.builder, {Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) => builder(context, () => (context as Element).markNeedsBuild());
}

 使用：

bool _withTree = true;

StateBuilder((BuildContext context, rebuild) {
        return Checkbox(
          value: _withTree,
          onChanged: (bool value) {
            _withTree = !_withTree;
            rebuild();
          },
        );
      },
    )

参考：7.7 对话框详解 | 《Flutter实战·第二版》