main_bloc.dart

import 'package:flutter/material.dart';

class MainNotifier {
  final notifierCounter = ValueNotifier(0);
  final notifierSlider = ValueNotifier(0.0);
  final notifierCheck = ValueNotifier(false);

  void incrementCounter() {
    notifierCounter.value = notifierCounter.value + 1;
  }

  void sliderChanged(double val) {
    notifierSlider.value = val;
  }

  void checkChanged(bool val) {
    notifierCheck.value = val;
  }
}

class MainBloc extends ChangeNotifier {
  int counter = 0;

  void incrementCounter() {
    counter++;
    notifyListeners();
  }
}

class MainBlocSlider extends ChangeNotifier {
  double sliderValue = 0;

  void sliderChanged(double val) {
    sliderValue = val;
    notifyListeners();
  }
}

samples_rendering.dart

import 'package:sample/main_bloc.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.red,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

const style = TextStyle(
  fontSize: 80,
  fontWeight: FontWeight.bold,
);

class _MyHomePageState extends State<MyHomePage> {
  final myNotifier = MainNotifier();

  @override
  Widget build(BuildContext context) {
    print('rebuild...');

    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            ValueListenableBuilder(
              valueListenable: myNotifier.notifierCounter,
              builder: (context, snapshot, _) {
                print('rebuild text');
                return Text(
                  '$snapshot',
                  style: style,
                );
              },
            ),
            const SizedBox(height: 30),
            Container(
              height: 1,
              color: Colors.grey,
            ),
            ValueListenableBuilder(
                valueListenable: myNotifier.notifierSlider,
                child: MyLogo(),
                builder: (context, snapshot, child334324) {
                  print('rebuild slider');
                  return Column(
                    children: [
                      Text(
                        '${snapshot.toStringAsFixed(2)}',
                        style: style,
                      ),
                      child334324,
                      Slider(
                        value: snapshot,
                        onChanged: myNotifier.sliderChanged,
                      ),
                    ],
                  );
                }),
            ValueListenableBuilder(
                valueListenable: myNotifier.notifierCheck,
                builder: (context, snapshot, _) {
                  print('rebuild checkbox');
                  return Checkbox(
                    value: snapshot,
                    onChanged: myNotifier.checkChanged,
                  );
                }),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: myNotifier.incrementCounter,
        child: Icon(Icons.add),
      ),
    );
  }
}

class MyLogo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    print('rebuild logo');
    return FlutterLogo(
      size: 100,
    );
  }
}

class HorizontalListWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container();
  }
}