FLutter中inheritedwidget的使用

import 'package:demoflutter/main_base2.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart' show rootBundle ;
import 'package:dio/dio.dart';

import 'dart:convert';
import 'dart:async';

import 'dart:io';



void main() {

  runApp(MaterialApp(
      title: "material",
      theme: ThemeData(
        backgroundColor: Colors.red,
        primaryColor: Colors.blue,
        splashColor: Colors.transparent
      ),
      home: Scaffold(
          appBar: AppBar(
            title: Text("CodeText"),
          ),
          // body: MyApp2())));
          // body: MyGridCountDemo())));
          //  body: GridViewBuildDemo())));
          // body: HomeContent())));
          //    body: HomeContent2())));
          // body: MyHomePage3())));
          // body: HYStartRating(rating:1))));
          // body: showDashLine())));
          // body: MyApp())));
          // body: MovieListItem(MovieItem.fromMap({"":""})))));
    body: HYHomePage())));
}


class HYDataWidget extends InheritedWidget {

    final int counter;

    HYDataWidget( {this.counter, Widget child}): super(child: child);

    static HYDataWidget of(BuildContext context){
      return context.dependOnInheritedWidgetOfExactType();
    }

  @override
  bool updateShouldNotify(HYDataWidget oldWidget) {
    // TODO: implement updateShouldNotify
    return oldWidget.counter !=this.counter;

    }

}




class HYHomePage extends StatefulWidget {
  @override
  _HYHomePageState createState() => _HYHomePageState();
}
class _HYHomePageState extends State {
  int data = 100;
  @override
  Widget build(BuildContext context) {
      return Scaffold(
          appBar: AppBar(title: Text("inheritedWidget"),),
          body: HYDataWidget(
            counter: data,
            child: Center(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  HYSHowData01()
                ],
              ),
            ),
          ),
        floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: (){
            setState(() {
              data++;
            });

          },
        ),
      );
  }

}


class ShowWidget extends StatefulWidget {
  @override
  _stateShowWidget createState() => _stateShowWidget();
}


class _stateShowWidget extends State{
  int count=0;
  @override
  Widget build(BuildContext context) {
    return Center(
       child: HYDataWidget(
         counter: count,
         child: FloatingActionButton(
           child:Text("sa"),
           onPressed: (){
             setState(() {
               ++count;
             });
           },
         ),
       ) ,
    );
  }
}

// class HYSHowData01 extends StatelessWidget {
//
//   @override
//   Widget build(BuildContext context){
//     // return Container();
//     int counter = HYDataWidget.of(context).counter;
//     return Card(
//       color: Colors.red,
//       child: Text('当前计数1111：${counter}'),
//     );
//   }
//
//
// }


class HYSHowData01 extends StatefulWidget {

  @override
  _stateHYSHowData01 createState() => _stateHYSHowData01();

}

class _stateHYSHowData01 extends State {
  @override
  void didChangeDependencies() {
    // TODO: implement didChangeDependencies
    super.didChangeDependencies();
    int counter = HYDataWidget.of(context).counter;
    print("改变啊   aa${counter}");

  }
  @override
  Widget build(BuildContext context){
    // return Container();
    int counter = HYDataWidget.of(context).counter;
    return Card(
      color: Colors.red,
      child: Text('当前计数1111：${counter}'),
    );
  }
}

class HYSHowData02 extends StatelessWidget {
  @override
  Widget build(BuildContext context){
    // return Container();
    return Card(
      color: Colors.red,
      child: Text('当前计数：100'),
    );
  }


}