Add game_template (#1180)

Adds a template / sample for games built in Flutter, with all the bells and whistles, like ads, in-app purchases, audio, main menu, settings, and so on.

Co-authored-by: Parker Lougheed
Co-authored-by: Shams Zakhour

game_template/lib/src/play_session/play_session_screen.dart

@@ -0,0 +1,180 @@
+// Copyright 2022, the Flutter project authors. Please see the AUTHORS file
+// for details. 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:async';
+
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:logging/logging.dart' hide Level;
+import 'package:provider/provider.dart';
+
+import '../ads/ads_controller.dart';
+import '../audio/audio_controller.dart';
+import '../audio/sounds.dart';
+import '../game_internals/level_state.dart';
+import '../games_services/games_services.dart';
+import '../games_services/score.dart';
+import '../in_app_purchase/in_app_purchase.dart';
+import '../level_selection/levels.dart';
+import '../player_progress/player_progress.dart';
+import '../style/confetti.dart';
+import '../style/palette.dart';
+
+class PlaySessionScreen extends StatefulWidget {
+  final GameLevel level;
+
+  const PlaySessionScreen(this.level, {Key? key}) : super(key: key);
+
+  @override
+  State<PlaySessionScreen> createState() => _PlaySessionScreenState();
+}
+
+class _PlaySessionScreenState extends State<PlaySessionScreen> {
+  static final _log = Logger('PlaySessionScreen');
+
+  static const _celebrationDuration = Duration(milliseconds: 2000);
+
+  static const _preCelebrationDuration = Duration(milliseconds: 500);
+
+  bool _duringCelebration = false;
+
+  late DateTime _startOfPlay;
+
+  @override
+  Widget build(BuildContext context) {
+    final palette = context.watch<Palette>();
+
+    return MultiProvider(
+      providers: [
+        ChangeNotifierProvider(
+          create: (context) => LevelState(
+            goal: widget.level.difficulty,
+            onWin: _playerWon,
+          ),
+        ),
+      ],
+      child: IgnorePointer(
+        ignoring: _duringCelebration,
+        child: Scaffold(
+          backgroundColor: palette.backgroundPlaySession,
+          body: Stack(
+            children: [
+              Center(
+                // This is the entirety of the "game".
+                child: Column(
+                  mainAxisAlignment: MainAxisAlignment.center,
+                  children: [
+                    Align(
+                      alignment: Alignment.centerRight,
+                      child: InkResponse(
+                        onTap: () => GoRouter.of(context).push('/settings'),
+                        child: Image.asset(
+                          'assets/images/settings.png',
+                          semanticLabel: 'Settings',
+                        ),
+                      ),
+                    ),
+                    const Spacer(),
+                    Text('Drag the slider to ${widget.level.difficulty}%'
+                        ' or above!'),
+                    Consumer<LevelState>(
+                      builder: (context, levelState, child) => Slider(
+                        label: 'Level Progress',
+                        autofocus: true,
+                        value: levelState.progress / 100,
+                        onChanged: (value) =>
+                            levelState.setProgress((value * 100).round()),
+                        onChangeEnd: (value) => levelState.evaluate(),
+                      ),
+                    ),
+                    const Spacer(),
+                    Padding(
+                      padding: const EdgeInsets.all(8.0),
+                      child: SizedBox(
+                        width: double.infinity,
+                        child: ElevatedButton(
+                          onPressed: () => GoRouter.of(context).pop(),
+                          child: const Text('Back'),
+                        ),
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+              SizedBox.expand(
+                child: Visibility(
+                  visible: _duringCelebration,
+                  child: IgnorePointer(
+                    child: Confetti(
+                      isStopped: !_duringCelebration,
+                    ),
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  @override
+  void initState() {
+    super.initState();
+
+    _startOfPlay = DateTime.now();
+
+    // Preload ad for the win screen.
+    final adsRemoved =
+        context.read<InAppPurchaseController?>()?.adRemoval.active ?? false;
+    if (!adsRemoved) {
+      final adsController = context.read<AdsController?>();
+      adsController?.preloadAd();
+    }
+  }
+
+  Future<void> _playerWon() async {
+    _log.info('Level ${widget.level.number} won');
+
+    final score = Score(
+      widget.level.number,
+      widget.level.difficulty,
+      DateTime.now().difference(_startOfPlay),
+    );
+
+    final playerProgress = context.read<PlayerProgress>();
+    playerProgress.setLevelReached(widget.level.number);
+
+    // Let the player see the game just after winning for a bit.
+    await Future<void>.delayed(_preCelebrationDuration);
+    if (!mounted) return;
+
+    setState(() {
+      _duringCelebration = true;
+    });
+
+    final audioController = context.read<AudioController>();
+    audioController.playSfx(SfxType.congrats);
+
+    final gamesServicesController = context.read<GamesServicesController?>();
+    if (gamesServicesController != null) {
+      // Award achievement.
+      if (widget.level.awardsAchievement) {
+        await gamesServicesController.awardAchievement(
+          android: widget.level.achievementIdAndroid!,
+          iOS: widget.level.achievementIdIOS!,
+        );
+      }
+
+      // Send score to leaderboard.
+      await gamesServicesController.submitLeaderboardScore(score);
+    }
+
+    /// Give the player some time to see the celebration animation.
+    await Future<void>.delayed(_celebrationDuration);
+    if (!mounted) return;
+
+    GoRouter.of(context).go('/play/won', extra: {'score': score});
+  }
+}