restructured the add to app samples (#698)

add_to_app/plugin/flutter_module_using_plugin/.gitignore

@@ -0,0 +1,42 @@
+.DS_Store
+.dart_tool/
+
+.packages
+.pub/
+
+.idea/
+.vagrant/
+.sconsign.dblite
+.svn/
+
+*.swp
+profile
+
+DerivedData/
+
+.generated/
+
+*.pbxuser
+*.mode1v3
+*.mode2v3
+*.perspectivev3
+
+!default.pbxuser
+!default.mode1v3
+!default.mode2v3
+!default.perspectivev3
+
+xcuserdata
+
+*.moved-aside
+
+*.pyc
+*sync/
+Icon?
+.tags*
+
+build/
+.android/
+.ios/
+.flutter-plugins
+.flutter-plugins-dependencies

add_to_app/plugin/flutter_module_using_plugin/.metadata

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+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 532a8fed41a4f6595965f02f3edf9666ba5ebf44
+  channel: master
+
+project_type: module

add_to_app/plugin/flutter_module_using_plugin/README.md

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+# flutter_module_using_plugin
+
+An example Flutter module that uses a native plugin, intended for use in the
+Flutter add-to-app samples. For more information on how to use it, see the
+[README.md](../README.md) parent directory.
+
+## Getting Started
+
+For more information about Flutter, check out
+[flutter.dev](https://flutter.dev).
+
+For instructions on how to integrate Flutter modules into your existing
+applications, see Flutter's
+[add-to-app documentation](https://flutter.dev/docs/development/add-to-app).

add_to_app/plugin/flutter_module_using_plugin/lib/cell.dart

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+// Copyright 2019 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:math';
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:sensors/sensors.dart';
+
+// This is on alternate entrypoint for this module to display Flutter UI in
+// a (multi-)view integration scenario.
+void main() {
+  runApp(Cell());
+}
+
+class Cell extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() => new _CellState();
+}
+
+class _CellState extends State<Cell> with WidgetsBindingObserver {
+  static const double gravity = 9.81;
+  static final AccelerometerEvent defaultPosition = AccelerometerEvent(0, 0, 0);
+
+  int cellNumber = 0;
+  Random _random;
+  AppLifecycleState appLifecycleState;
+
+  @override
+  void initState() {
+    final channel = MethodChannel('dev.flutter.example/cell');
+    channel.setMethodCallHandler((MethodCall call) async {
+      if (call.method == 'setCellNumber') {
+        setState(() {
+          cellNumber = call.arguments as int;
+          _random = Random(cellNumber);
+        });
+      }
+    });
+    // Keep track of what the current platform lifecycle state is.
+    WidgetsBinding.instance.addObserver(this);
+    super.initState();
+  }
+
+  @override
+  void dispose() {
+    WidgetsBinding.instance.removeObserver(this);
+    super.dispose();
+  }
+
+  @override
+  void didChangeAppLifecycleState(AppLifecycleState state) {
+    setState(() {
+      appLifecycleState = state;
+    });
+  }
+
+  // Show a random bright color.
+  Color randomLightColor() {
+    _random ??= Random(cellNumber);
+
+    return Color.fromARGB(255, _random.nextInt(50) + 205,
+        _random.nextInt(50) + 205, _random.nextInt(50) + 205);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      // The Flutter cells will be noticeably different (due to background color
+      // and the Flutter logo). The banner breaks immersion.
+      debugShowCheckedModeBanner: false,
+      home: Container(
+        color: Colors.white,
+        child: Builder(
+          builder: (BuildContext context) {
+            return Card(
+              // Mimic the platform Material look.
+              margin: EdgeInsets.symmetric(horizontal: 36, vertical: 24),
+              shape: RoundedRectangleBorder(
+                borderRadius: BorderRadius.circular(16),
+              ),
+              elevation: 16,
+              color: randomLightColor(),
+              child: Stack(
+                children: [
+                  Center(
+                    child: Column(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        Text(
+                          // Show a number provided by the platform based on
+                          // the cell's index.
+                          cellNumber.toString(),
+                          style: Theme.of(context).textTheme.headline3,
+                        ),
+                      ],
+                    ),
+                  ),
+                  Positioned(
+                    left: 42,
+                    top: 0,
+                    bottom: 0,
+                    child: Opacity(
+                      opacity: 0.2,
+                      child: StreamBuilder(
+                        // Don't continuously rebuild for nothing when the
+                        // cell isn't visible.
+                        stream: appLifecycleState == AppLifecycleState.resumed
+                            ? accelerometerEvents
+                            : Stream.value(defaultPosition),
+                        initialData: defaultPosition,
+                        builder: (BuildContext context,
+                            AsyncSnapshot<AccelerometerEvent> snapshot) {
+                          return Transform(
+                              // Figure out the phone's orientation relative
+                              // to gravity's direction. Ignore the z vector.
+                              transform: Matrix4.rotationX(
+                                  snapshot.data.y / gravity * pi / 2)
+                                ..multiply(Matrix4.rotationY(
+                                    snapshot.data.x / gravity * pi / 2)),
+                              alignment: Alignment.center,
+                              child: FlutterLogo(size: 72));
+                        },
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            );
+          },
+        ),
+      ),
+    );
+  }
+}

add_to_app/plugin/flutter_module_using_plugin/lib/main.dart

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+// Copyright 2019 The Flutter team. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:provider/provider.dart';
+import 'package:url_launcher/url_launcher.dart' as launcher;
+
+import 'cell.dart';
+
+/// The entrypoint for the flutter module.
+void main() {
+  // This call ensures the Flutter binding has been set up before creating the
+  // MethodChannel-based model.
+  WidgetsFlutterBinding.ensureInitialized();
+
+  final model = CounterModel();
+
+  runApp(
+    ChangeNotifierProvider.value(
+      value: model,
+      child: MyApp(),
+    ),
+  );
+}
+
+/// This is on alternate entrypoint for this module to display Flutter UI in
+/// a (multi-)view integration scenario.
+// This is unfortunately in this file due to
+// https://github.com/flutter/flutter/issues/72630.
+void showCell() {
+  runApp(Cell());
+}
+
+/// A simple model that uses a [MethodChannel] as the source of truth for the
+/// state of a counter.
+///
+/// Rather than storing app state data within the Flutter module itself (where
+/// the native portions of the app can't access it), this module passes messages
+/// back to the containing app whenever it needs to increment or retrieve the
+/// value of the counter.
+class CounterModel extends ChangeNotifier {
+  CounterModel() {
+    _channel.setMethodCallHandler(_handleMessage);
+    _channel.invokeMethod('requestCounter');
+  }
+
+  final _channel = MethodChannel('dev.flutter.example/counter');
+
+  int _count = 0;
+
+  int get count => _count;
+
+  void increment() {
+    _channel.invokeMethod('incrementCounter');
+  }
+
+  Future<dynamic> _handleMessage(MethodCall call) async {
+    if (call.method == 'reportCounter') {
+      _count = call.arguments as int;
+      notifyListeners();
+    }
+  }
+}
+
+/// The "app" displayed by this module.
+///
+/// It offers two routes, one suitable for displaying as a full screen and
+/// another designed to be part of a larger UI.
+class MyApp extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Module Title',
+      routes: {
+        '/': (context) => FullScreenView(),
+        '/mini': (context) => Contents(),
+      },
+    );
+  }
+}
+
+/// Wraps [Contents] in a Material [Scaffold] so it looks correct when displayed
+/// full-screen.
+class FullScreenView extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Full-screen Flutter with plugin'),
+      ),
+      body: const Contents(showExit: true),
+    );
+  }
+}
+
+/// The actual content displayed by the module.
+///
+/// This widget displays info about the state of a counter and how much room (in
+/// logical pixels) it's been given. It also offers buttons to increment the
+/// counter, opening the Flutter documentation via the url_launcher plugin, and
+/// (optionally) close the Flutter view.
+class Contents extends StatelessWidget {
+  final bool showExit;
+
+  const Contents({this.showExit = false});
+
+  @override
+  Widget build(BuildContext context) {
+    final mediaInfo = MediaQuery.of(context);
+
+    return SizedBox.expand(
+      child: Stack(
+        children: [
+          Positioned.fill(
+            child: DecoratedBox(
+              decoration: BoxDecoration(
+                color: Theme.of(context).scaffoldBackgroundColor,
+              ),
+            ),
+          ),
+          Positioned.fill(
+            child: Opacity(
+              opacity: .25,
+              child: FittedBox(
+                fit: BoxFit.cover,
+                child: FlutterLogo(),
+              ),
+            ),
+          ),
+          Center(
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.center,
+              children: [
+                Text(
+                  'Window is ${mediaInfo.size.width.toStringAsFixed(1)} x '
+                  '${mediaInfo.size.height.toStringAsFixed(1)}',
+                  style: Theme.of(context).textTheme.headline5,
+                ),
+                SizedBox(height: 16),
+                Consumer<CounterModel>(
+                  builder: (context, model, child) {
+                    return Text(
+                      'Taps: ${model.count}',
+                      style: Theme.of(context).textTheme.headline5,
+                    );
+                  },
+                ),
+                SizedBox(height: 16),
+                Consumer<CounterModel>(
+                  builder: (context, model, child) {
+                    return ElevatedButton(
+                      onPressed: () => model.increment(),
+                      child: Text('Tap me!'),
+                    );
+                  },
+                ),
+                ElevatedButton(
+                  onPressed: () async {
+                    // Use the url_launcher plugin to open the Flutter docs in
+                    // a browser.
+                    final url = 'https://flutter.dev/docs';
+                    if (await launcher.canLaunch(url)) {
+                      launcher.launch(url);
+                    }
+                  },
+                  child: Text('Open Flutter Docs'),
+                ),
+                if (showExit) ...[
+                  SizedBox(height: 16),
+                  ElevatedButton(
+                    onPressed: () => SystemNavigator.pop(),
+                    child: Text('Exit this screen'),
+                  ),
+                ],
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}

add_to_app/plugin/flutter_module_using_plugin/pubspec.lock

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+# Generated by pub
+# See https://dart.dev/tools/pub/glossary#lockfile
+packages:
+  async:
+    dependency: transitive
+    description:
+      name: async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.5.0-nullsafety.3"
+  boolean_selector:
+    dependency: transitive
+    description:
+      name: boolean_selector
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0-nullsafety.3"
+  characters:
+    dependency: transitive
+    description:
+      name: characters
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0-nullsafety.5"
+  charcode:
+    dependency: transitive
+    description:
+      name: charcode
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0-nullsafety.3"
+  clock:
+    dependency: transitive
+    description:
+      name: clock
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0-nullsafety.3"
+  collection:
+    dependency: transitive
+    description:
+      name: collection
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.15.0-nullsafety.5"
+  fake_async:
+    dependency: transitive
+    description:
+      name: fake_async
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0-nullsafety.3"
+  flutter:
+    dependency: "direct main"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
+  flutter_test:
+    dependency: "direct dev"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
+  flutter_web_plugins:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.6.3-nullsafety.3"
+  matcher:
+    dependency: transitive
+    description:
+      name: matcher
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.12.10-nullsafety.3"
+  meta:
+    dependency: transitive
+    description:
+      name: meta
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0-nullsafety.6"
+  nested:
+    dependency: transitive
+    description:
+      name: nested
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.0.4"
+  path:
+    dependency: transitive
+    description:
+      name: path
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.8.0-nullsafety.3"
+  plugin_platform_interface:
+    dependency: transitive
+    description:
+      name: plugin_platform_interface
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.3"
+  provider:
+    dependency: "direct main"
+    description:
+      name: provider
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "4.3.2+3"
+  sensors:
+    dependency: "direct main"
+    description:
+      name: sensors
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.4.2+6"
+  sky_engine:
+    dependency: transitive
+    description: flutter
+    source: sdk
+    version: "0.0.99"
+  source_span:
+    dependency: transitive
+    description:
+      name: source_span
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.8.0-nullsafety.4"
+  stack_trace:
+    dependency: transitive
+    description:
+      name: stack_trace
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.10.0-nullsafety.6"
+  stream_channel:
+    dependency: transitive
+    description:
+      name: stream_channel
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0-nullsafety.3"
+  string_scanner:
+    dependency: transitive
+    description:
+      name: string_scanner
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.1.0-nullsafety.3"
+  term_glyph:
+    dependency: transitive
+    description:
+      name: term_glyph
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.2.0-nullsafety.3"
+  test_api:
+    dependency: transitive
+    description:
+      name: test_api
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.2.19-nullsafety.6"
+  typed_data:
+    dependency: transitive
+    description:
+      name: typed_data
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.3.0-nullsafety.5"
+  url_launcher:
+    dependency: "direct main"
+    description:
+      name: url_launcher
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "5.7.10"
+  url_launcher_linux:
+    dependency: transitive
+    description:
+      name: url_launcher_linux
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.0.1+4"
+  url_launcher_macos:
+    dependency: transitive
+    description:
+      name: url_launcher_macos
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.0.1+9"
+  url_launcher_platform_interface:
+    dependency: transitive
+    description:
+      name: url_launcher_platform_interface
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.9"
+  url_launcher_web:
+    dependency: transitive
+    description:
+      name: url_launcher_web
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.1.5+1"
+  url_launcher_windows:
+    dependency: transitive
+    description:
+      name: url_launcher_windows
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.0.1+3"
+  vector_math:
+    dependency: transitive
+    description:
+      name: vector_math
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0-nullsafety.5"
+sdks:
+  dart: ">=2.12.0-0.0 <3.0.0"
+  flutter: ">=1.22.0"

add_to_app/plugin/flutter_module_using_plugin/pubspec.yaml

@@ -0,0 +1,32 @@
+name: flutter_module_using_plugin
+description: An example Flutter module that uses a plugin.
+
+version: 1.0.0+1
+
+environment:
+  sdk: ">=2.6.0-dev <3.0.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+  provider: ^4.1.0
+  url_launcher: ^5.2.5
+  sensors: ^0.4.2
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+flutter:
+  uses-material-design: true
+
+  # This section identifies your Flutter project as a module meant for
+  # embedding in a native host app.  These identifiers should _not_ ordinarily
+  # be changed after generation - they are used to ensure that the tooling can
+  # maintain consistency when adding or modifying assets and plugins.
+  # They also do not have any bearing on your native host application's
+  # identifiers, which may be completely independent or the same as these.
+  module:
+    androidX: true
+    androidPackage: dev.flutter.example.flutter_module_using_plugin
+    iosBundleIdentifier: dev.flutter.example.flutterModuleUsingPlugin

add_to_app/plugin/flutter_module_using_plugin/test/widget_test.dart

@@ -0,0 +1,49 @@
+// This is a basic Flutter widget test.
+//
+// To perform an interaction with a widget in your test, use the WidgetTester
+// utility that Flutter provides. For example, you can send tap and scroll
+// gestures. You can also use WidgetTester to find child widgets in the widget
+// tree, read text, and verify that the values of widget properties are correct.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:flutter_module_using_plugin/main.dart';
+import 'package:provider/provider.dart';
+
+class MockCounterModel extends ChangeNotifier implements CounterModel {
+  int _count = 0;
+
+  int get count => _count;
+
+  void increment() {
+    _count++;
+    notifyListeners();
+  }
+}
+
+void main() {
+  testWidgets('MiniView smoke test', (WidgetTester tester) async {
+    // Build our app and trigger a frame.
+    await tester.pumpWidget(
+      MaterialApp(
+        home: ChangeNotifierProvider<CounterModel>.value(
+          value: MockCounterModel(),
+          child: Contents(),
+        ),
+      ),
+    );
+
+    // Verify that our counter starts at 0.
+    expect(find.text('Taps: 0'), findsOneWidget);
+    expect(find.text('Taps: 1'), findsNothing);
+
+    // Tap the '+' icon and trigger a frame.
+    await tester.tap(find.text('Tap me!'));
+    await tester.pump();
+
+    // Verify that our counter has incremented.
+    expect(find.text('Taps: 0'), findsNothing);
+    expect(find.text('Taps: 1'), findsOneWidget);
+  });
+}