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/settings/persistence/local_storage_settings_persistence.dart

@@ -0,0 +1,62 @@
+// 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 'package:shared_preferences/shared_preferences.dart';
+
+import 'settings_persistence.dart';
+
+/// An implementation of [SettingsPersistence] that uses
+/// `package:shared_preferences`.
+class LocalStorageSettingsPersistence extends SettingsPersistence {
+  final Future<SharedPreferences> instanceFuture =
+      SharedPreferences.getInstance();
+
+  @override
+  Future<bool> getMusicOn() async {
+    final prefs = await instanceFuture;
+    return prefs.getBool('musicOn') ?? true;
+  }
+
+  @override
+  Future<bool> getMuted({required bool defaultValue}) async {
+    final prefs = await instanceFuture;
+    return prefs.getBool('mute') ?? defaultValue;
+  }
+
+  @override
+  Future<String> getPlayerName() async {
+    final prefs = await instanceFuture;
+    return prefs.getString('playerName') ?? 'Player';
+  }
+
+  @override
+  Future<bool> getSoundsOn() async {
+    final prefs = await instanceFuture;
+    return prefs.getBool('soundsOn') ?? true;
+  }
+
+  @override
+  Future<void> saveMusicOn(bool value) async {
+    final prefs = await instanceFuture;
+    await prefs.setBool('musicOn', value);
+  }
+
+  @override
+  Future<void> saveMuted(bool value) async {
+    final prefs = await instanceFuture;
+    await prefs.setBool('mute', value);
+  }
+
+  @override
+  Future<void> savePlayerName(String value) async {
+    final prefs = await instanceFuture;
+    await prefs.setString('playerName', value);
+  }
+
+  @override
+  Future<void> saveSoundsOn(bool value) async {
+    final prefs = await instanceFuture;
+    await prefs.setBool('soundsOn', value);
+  }
+}

game_template/lib/src/settings/persistence/memory_settings_persistence.dart

@@ -0,0 +1,41 @@
+// 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 'package:game_template/src/settings/persistence/settings_persistence.dart';
+
+/// An in-memory implementation of [SettingsPersistence].
+/// Useful for testing.
+class MemoryOnlySettingsPersistence implements SettingsPersistence {
+  bool musicOn = true;
+
+  bool soundsOn = true;
+
+  bool muted = false;
+
+  String playerName = 'Player';
+
+  @override
+  Future<bool> getMusicOn() async => musicOn;
+
+  @override
+  Future<bool> getMuted({required bool defaultValue}) async => muted;
+
+  @override
+  Future<String> getPlayerName() async => playerName;
+
+  @override
+  Future<bool> getSoundsOn() async => soundsOn;
+
+  @override
+  Future<void> saveMusicOn(bool value) async => musicOn = value;
+
+  @override
+  Future<void> saveMuted(bool value) async => muted = value;
+
+  @override
+  Future<void> savePlayerName(String value) async => playerName = value;
+
+  @override
+  Future<void> saveSoundsOn(bool value) async => soundsOn = value;
+}

game_template/lib/src/settings/persistence/settings_persistence.dart

@@ -0,0 +1,25 @@
+// 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.
+
+/// An interface of persistence stores for settings.
+///
+/// Implementations can range from simple in-memory storage through
+/// local preferences to cloud-based solutions.
+abstract class SettingsPersistence {
+  Future<bool> getMusicOn();
+
+  Future<bool> getMuted({required bool defaultValue});
+
+  Future<String> getPlayerName();
+
+  Future<bool> getSoundsOn();
+
+  Future<void> saveMusicOn(bool value);
+
+  Future<void> saveMuted(bool value);
+
+  Future<void> savePlayerName(String value);
+
+  Future<void> saveSoundsOn(bool value);
+}