follow_the_leader 0.0.4+3

Widgets that follow other widgets.

example/lib/main.dart

import 'package:example/demo_hover.dart';
import 'package:example/demo_interactive_viewer.dart';
import 'package:example/demo_kitchen_sink.dart';
import 'package:example/demo_page_list_viewport.dart';
import 'package:example/demo_scaling.dart';
import 'package:example/demo_scrollables.dart';
import 'package:flutter/material.dart';
import 'package:follow_the_leader/follow_the_leader.dart';
import 'package:logging/logging.dart';

import 'demo_orbiting_circles.dart';

void main() {
  FtlLogs.initLoggers(Level.FINEST, {
    // FtlLogs.leader,
    // FtlLogs.follower,
    // FtlLogs.link,
    // FtlLogs.boundary,
    // appLog,
  });
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Follow the Leader Example',
      theme: ThemeData.dark(),
      debugShowCheckedModeBanner: false,
      home: const ExampleApp(),
    );
  }
}

class ExampleApp extends StatefulWidget {
  const ExampleApp({Key? key}) : super(key: key);

  @override
  State createState() => _ExampleAppState();
}

class _ExampleAppState extends State<ExampleApp> {
  final _scaffoldKey = GlobalKey<ScaffoldState>();

  _MenuItem _selectedMenu = _items.first;

  void _closeDrawer() {
    if (_scaffoldKey.currentState!.isDrawerOpen) {
      Navigator.of(context).pop();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
      ),
      extendBodyBehindAppBar: true,
      body: Builder(builder: (bodyContext) {
        // Use an intermediate Builder so that the BuildContext that we
        // give to the pageBuilder has finite layout bounds.
        return _selectedMenu.pageBuilder(bodyContext);
      }),
      drawer: _buildDrawer(),
    );
  }

  Widget _buildDrawer() {
    return Drawer(
      child: SingleChildScrollView(
        primary: false,
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 32, vertical: 48),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              for (final item in _items) ...[
                _DrawerButton(
                  title: item.title,
                  onPressed: () => setState(() {
                    _selectedMenu = item;
                    _closeDrawer();
                  }),
                  isSelected: _selectedMenu == item,
                ),
                const SizedBox(height: 24),
              ],
            ],
          ),
        ),
      ),
    );
  }
}

final _items = [
  _MenuItem(
    title: 'Follow the Leader',
    pageBuilder: (context) => const KitchenSinkDemo(),
  ),
  _MenuItem(
    title: 'Page List Viewport',
    pageBuilder: (context) => const PageListViewportDemo(),
  ),
  _MenuItem(
    title: 'Interactive Viewer',
    pageBuilder: (context) => const InteractiveViewerDemo(),
  ),
  _MenuItem(
    title: 'Hover',
    pageBuilder: (context) => const HoverDemo(),
  ),
  _MenuItem(
    title: 'Orbiting Circles',
    pageBuilder: (context) => const OrbitingCirclesDemo(),
  ),
  _MenuItem(
    title: 'Scaling',
    pageBuilder: (context) => const ScalingDemo(),
  ),
  _MenuItem(
    title: 'Scrollables',
    pageBuilder: (context) => const ScrollablesDemo(),
  ),
];

class _DrawerButton extends StatelessWidget {
  const _DrawerButton({
    Key? key,
    required this.title,
    this.isSelected = false,
    required this.onPressed,
  }) : super(key: key);

  final String title;
  final bool isSelected;
  final VoidCallback onPressed;

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      child: ElevatedButton(
        style: ButtonStyle(
            backgroundColor: MaterialStateColor.resolveWith((states) {
              if (isSelected) {
                return const Color(0xFFBBBBBB);
              }

              if (states.contains(MaterialState.hovered)) {
                return Colors.grey.withOpacity(0.1);
              }

              return Colors.transparent;
            }),
            foregroundColor:
                MaterialStateColor.resolveWith((states) => isSelected ? Colors.white : const Color(0xFFBBBBBB)),
            elevation: MaterialStateProperty.resolveWith((states) => 0),
            padding: MaterialStateProperty.resolveWith((states) => const EdgeInsets.all(16))),
        onPressed: isSelected ? null : onPressed,
        child: Center(child: Text(title)),
      ),
    );
  }
}

class _MenuItem {
  const _MenuItem({
    required this.title,
    required this.pageBuilder,
  });

  final String title;
  final WidgetBuilder pageBuilder;
}