mvvm_plus 1.1.0

MVVM+ is a lightweight Flutter implementation of MVVM, plus a locator for sharing states via a global registry (like GetIt) or inherited widgets (like Provider).

example/lib/main.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:mvvm_plus/mvvm_plus.dart';
import 'package:bilocator/bilocator.dart';

void main() => runApp(myApp());

Widget myApp() => Bilocators(
        delegates: [
          BilocatorDelegate<ColorService>(
              builder: () => ColorService(milliSeconds: 1500), name: 'letter'),
          BilocatorDelegate<ColorService>(
              builder: () => ColorService(milliSeconds: 1500), name: 'number'),
        ],
        child: MaterialApp(
            debugShowCheckedModeBanner: false, home: CounterPage()));

class CounterPage extends View<CounterPageViewModel> {
  CounterPage({super.key})
      : super(
            location: Location.registry, builder: () => CounterPageViewModel());

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Center(
            child:
                Column(mainAxisAlignment: MainAxisAlignment.center, children: <
                    Widget>[
          Row(mainAxisAlignment: MainAxisAlignment.center, children: <Widget>[
            Text(viewModel.letterCount.value,
                style: TextStyle(
                    fontSize: 64,
                    color: listenTo<ColorService>(name: 'letter').color.value)),
            Text(viewModel.numberCounter.value.toString(),
                style: TextStyle(
                    fontSize: 64,
                    color: listenTo<ColorService>(name: 'number').color.value)),
          ]),
        ])),
        floatingActionButton: IncrementButton());
  }
}

class CounterPageViewModel extends ViewModel {
  late final numberCounter = createProperty<int>(0);
  late final letterCount = createProperty<String>('a');

  void incrementNumber() => numberCounter.value =
      numberCounter.value == 9 ? 0 : numberCounter.value + 1;
  void incrementLetter() => letterCount.value = letterCount.value == 'z'
      ? 'a'
      : String.fromCharCode(letterCount.value.codeUnits[0] + 1);
}

class ColorService extends Model {
  ColorService({required int milliSeconds}) {
    _timer = Timer.periodic(Duration(milliseconds: milliSeconds), (_) {
      color.value = <Color>[
        Colors.red,
        Colors.black,
        Colors.blue,
        Colors.orange
      ][++_counter % 4];
    });
  }

  int _counter = 0;
  late final color = createProperty<Color>(Colors.orange);
  late Timer _timer;

  @override
  void dispose() {
    _timer.cancel();
    super.dispose();
  }
}

class IncrementButton extends View<IncrementButtonViewModel> {
  IncrementButton({super.key})
      : super(builder: () => IncrementButtonViewModel());

  @override
  Widget build(BuildContext context) {
    return FloatingActionButton(
      onPressed: viewModel.incrementCounter,
      child: Text(viewModel.buttonText, style: const TextStyle(fontSize: 24)),
    );
  }
}

class IncrementButtonViewModel extends ViewModel {
  late final isNumber = createProperty<bool>(false);
  String get buttonText => isNumber.value ? '+1' : '+a';
  void incrementCounter() {
    isNumber.value
        ? get<CounterPageViewModel>().incrementNumber()
        : get<CounterPageViewModel>().incrementLetter();
    isNumber.value = !isNumber.value;
  }
}