Filter example pass controller through constructor

main.dart

/*
 * Filter example pass controller through constructor
 * https://gist.github.com/PlugFox/1e011d3b3737d59697e09bc6e59f422f
 * https://dartpad.dev/1e011d3b3737d59697e09bc6e59f422f
 * Matiunin Mikhail <plugfox@gmail.com>, 19 May 2022
 */

import 'dart:async';
import 'dart:math' as math;

import 'package:flutter/material.dart';

void main() => runZonedGuarded<Future<void>>(() async {
      runApp(const App());
    }, (error, stackTrace) {
      print('Error: $error, stackTrace: $stackTrace');
    });

/// {@template app}
/// App widget
/// {@endtemplate}
class App extends StatelessWidget {
  /// {@macro app}
  const App({
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) => const MaterialApp(
        title: 'Filter example',
        debugShowCheckedModeBanner: false,
        home: HomeScreen(),
      );
} // App

// --- Home screen with filter --- //

/// {@template main}
/// HomeScreen widget
/// {@endtemplate}
class HomeScreen extends StatefulWidget {
  /// {@macro main}
  const HomeScreen({
    Key? key,
  }) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
} // HomeScreen

/// State for widget HomeScreen
class _HomeScreenState extends State<HomeScreen> {
  static final math.Random _rnd = math.Random();
  static const int _kMax = 100;
  final List<int> _sourceList =
      Iterable<int>.generate(_kMax, (_) => _rnd.nextInt(_kMax))
          .toList(growable: false);

  final ValueNotifier<Filter> _filterController =
      ValueNotifier<Filter>(const Filter());

  @override
  void dispose() {
    _filterController.dispose();
    super.dispose();
  }

  /// Open filter dialog
  Future<void> _openFilter(BuildContext context) => showDialog<Filter?>(
        context: context,
        builder: (context) => FilterDialog(controller: _filterController),
      );

  bool _applyFilter(int data, Filter filter) {
    if (data.isEven && filter.even) {
      return true;
    } else if (data.isOdd && filter.odd) {
      return true;
    }
    return false;
  }

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          title: const Text('Home Screen'),
          actions: <Widget>[
            // Filter button:
            CircleAvatar(
              radius: 20,
              child: IconButton(
                onPressed: () => _openFilter(context),
                icon: const Icon(Icons.filter_list),
              ),
            ),
            const SizedBox(width: 14),
          ],
        ),
        // Body content:
        body: SafeArea(
          child: ValueListenableBuilder<Filter>(
            valueListenable: _filterController,
            builder: (context, filter, _) {
              final list = _sourceList
                  .where((element) => _applyFilter(element, filter))
                  .toList(growable: false);
              return ListView.builder(
                itemCount: list.length,
                itemBuilder: (context, index) => ListTile(
                  title: Text(
                    list[index].toString(),
                  ),
                  subtitle: Text(
                    list[index].isEven ? 'even' : 'odd',
                  ),
                ),
              );
            },
          ),
        ),
      );
} // _HomeScreenState

/// Filter result
@immutable
class Filter {
  /// Filter result
  const Filter({
    this.even = true,
    this.odd = true,
  });

  /// Show even numbers
  final bool even;

  /// Show odd numbers
  final bool odd;
}

/// {@template filter_dialog}
/// FilterDialog widget
/// {@endtemplate}
class FilterDialog extends StatefulWidget {
  /// {@macro filter_dialog}
  const FilterDialog({
    required this.controller,
    Key? key,
  }) : super(key: key);

  final ValueNotifier<Filter> controller;

  @override
  State<FilterDialog> createState() => _FilterDialogState();
} // FilterDialog

/// State for widget FilterDialog
class _FilterDialogState extends State<FilterDialog> {
  bool _even = true;
  bool _odd = true;

  @override
  void initState() {
    super.initState();
    _even = widget.controller.value.even;
    _odd = widget.controller.value.odd;
  }

  void _cancel(BuildContext context) => Navigator.pop(context, null);
  void _accept(BuildContext context) {
    widget.controller.value = Filter(even: _even, odd: _odd);
    Navigator.pop(context, null);
  }

  @override
  Widget build(BuildContext context) => SimpleDialog(
        title: const Text('Filter dialog'),
        children: <Widget>[
          StatefulBuilder(
            builder: (context, setState) => CheckboxListTile(
              title: const Text('Even'),
              value: _even,
              onChanged: (value) => setState(
                () => _even = value ?? false,
              ),
            ),
          ),
          StatefulBuilder(
            builder: (context, setState) => CheckboxListTile(
              title: const Text('Odd'),
              value: _odd,
              onChanged: (value) => setState(
                () => _odd = value ?? false,
              ),
            ),
          ),
          Row(
            mainAxisSize: MainAxisSize.max,
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            crossAxisAlignment: CrossAxisAlignment.center,
            children: <Widget>[
              OutlinedButton(
                onPressed: () => _cancel(context),
                child: const Text('Cancel'),
              ),
              ElevatedButton(
                onPressed: () => _accept(context),
                child: const Text('Accept'),
              ),
            ],
          )
        ],
      );
} // _FilterDialogState