Make gameRef late (#742)

examples/lib/stories/components/composability.dart

@@ -1,7 +1,7 @@
 import 'package:flame/components.dart';
 import 'package:flame/game.dart';
 
-class Square extends PositionComponent with HasGameRef<Composability> {
+class Square extends PositionComponent {
   Square(Vector2 position, Vector2 size, {double angle = 0}) {
     this.position.setFrom(position);
     this.size.setFrom(size);

examples/lib/stories/components/debug.dart

@@ -20,14 +20,14 @@ class LogoCompomnent extends SpriteComponent with HasGameRef<DebugGame> {
     final rect = toRect();
 
     if ((x <= 0 && xDirection == -1) ||
-        (rect.right >= gameRef!.size.x && xDirection == 1)) {
+        (rect.right >= gameRef.size.x && xDirection == 1)) {
       xDirection = xDirection * -1;
     }
 
     y += yDirection * speed * dt;
 
     if ((y <= 0 && yDirection == -1) ||
-        (rect.bottom >= gameRef!.size.y && yDirection == 1)) {
+        (rect.bottom >= gameRef.size.y && yDirection == 1)) {
       yDirection = yDirection * -1;
     }
   }

examples/lib/stories/controls/draggables.dart

@@ -39,7 +39,7 @@ class DraggableSquare extends PositionComponent
       return false;
     }
 
-    final localCoords = gameRef!.convertGlobalToLocalCoordinate(
+    final localCoords = gameRef.convertGlobalToLocalCoordinate(
       details.globalPosition.toVector2(),
     );
     position.setFrom(localCoords - dragDeltaPosition);

examples/lib/stories/parallax/component.dart

@@ -13,7 +13,7 @@ class MyParallaxComponent extends ParallaxComponent
     with HasGameRef<ComponentParallaxGame> {
   @override
   Future<void> onLoad() async {
-    parallax = await gameRef!.loadParallax(
+    parallax = await gameRef.loadParallax(
       [
         'parallax/bg.png',
         'parallax/mountain-far.png',

examples/lib/stories/sprites/spritebatch_auto_load.dart

@@ -9,7 +9,7 @@ class MySpriteBatchComponent extends SpriteBatchComponent
     with HasGameRef<SpritebatchAutoLoadGame> {
   @override
   Future<void> onLoad() async {
-    final spriteBatch = await gameRef!.loadSpriteBatch('boom.png');
+    final spriteBatch = await gameRef.loadSpriteBatch('boom.png');
     this.spriteBatch = spriteBatch;
 
     spriteBatch.add(
@@ -26,7 +26,7 @@ class MySpriteBatchComponent extends SpriteBatchComponent
       color: Colors.redAccent,
     );
 
-    final size = gameRef!.size;
+    final size = gameRef.size;
     const num = 100;
     final r = Random();
     for (var i = 0; i < num; ++i) {

examples/lib/stories/utils/camera_and_viewport.dart

@@ -24,7 +24,7 @@ class MovableSquare extends SquareComponent
     timer = Timer(3.0)
       ..stop()
       ..callback = () {
-        gameRef!.camera.setRelativeOffset(Anchor.center.toVector2());
+        gameRef.camera.setRelativeOffset(Anchor.center.toVector2());
       };
   }
 
@@ -50,7 +50,7 @@ class MovableSquare extends SquareComponent
   @override
   void onCollision(Set<Vector2> points, Collidable other) {
     if (other is Rock) {
-      gameRef!.camera.setRelativeOffset(Anchor.topCenter.toVector2());
+      gameRef.camera.setRelativeOffset(Anchor.topCenter.toVector2());
       timer.start();
     }
   }

packages/flame/CHANGELOG.md

@@ -16,6 +16,7 @@
  - Revamp all the docs to be up to date with v1.0.0
  - Make Assets and Images caches have a configurable prefix
  - Add `followVector2` method to the `Camera`
+ - Make `gameRef` late
 
 ## 1.0.0-rc8
  - Migrate to null safety

packages/flame/lib/src/components/base_component.dart

@@ -143,7 +143,10 @@ abstract class BaseComponent extends Component {
   /// For children that don't need preparation from the game instance can
   /// disregard both the options given above.
   Future<void> addChild(Component child, {Game? gameRef}) async {
-    gameRef ??= (this as HasGameRef).gameRef;
+    if (this is HasGameRef) {
+      final c = this as HasGameRef;
+      gameRef ??= c.hasGameRef ? c.gameRef : null;
+    }
     if (gameRef is BaseGame) {
       gameRef.prepare(child);
     }

packages/flame/lib/src/components/joystick/joystick_action.dart

@@ -67,7 +67,7 @@ class JoystickAction extends BaseComponent with Draggable, HasGameRef {
 
   @override
   Future<void> onLoad() async {
-    initialize(gameRef!.size);
+    initialize(gameRef.size);
   }
 
   @override
@@ -188,7 +188,7 @@ class JoystickAction extends BaseComponent with Draggable, HasGameRef {
   @override
   bool onDragUpdate(int pointerId, DragUpdateDetails details) {
     if (_dragging) {
-      _dragPosition = gameRef!.convertGlobalToLocalCoordinate(
+      _dragPosition = gameRef.convertGlobalToLocalCoordinate(
         details.globalPosition.toVector2(),
       );
       return true;

packages/flame/lib/src/components/joystick/joystick_directional.dart

@@ -50,7 +50,7 @@ class JoystickDirectional extends BaseComponent with Draggable, HasGameRef {
 
   @override
   Future<void> onLoad() async {
-    initialize(gameRef!.size);
+    initialize(gameRef.size);
   }
 
   @override
@@ -163,7 +163,7 @@ class JoystickDirectional extends BaseComponent with Draggable, HasGameRef {
   @override
   bool onDragUpdate(int pointerId, DragUpdateDetails details) {
     if (_dragging) {
-      _dragPosition = gameRef!.convertGlobalToLocalCoordinate(
+      _dragPosition = gameRef.convertGlobalToLocalCoordinate(
         details.globalPosition.toVector2(),
       );
       return false;

packages/flame/lib/src/components/mixins/has_game_ref.dart

@@ -1,5 +1,26 @@
+import '../../../components.dart';
 import '../../game/game.dart';
 
 mixin HasGameRef<T extends Game> {
-  T? gameRef;
+  T? _gameRef;
+
+  T get gameRef {
+    final ref = _gameRef;
+    if (ref == null) {
+      throw 'Accessing gameRef before the component was added to the game!';
+    }
+    return ref;
+  }
+
+  bool get hasGameRef => _gameRef != null;
+
+  set gameRef(T gameRef) {
+    _gameRef = gameRef;
+    if (this is BaseComponent) {
+      (this as BaseComponent)
+          .children
+          .whereType<HasGameRef<T>>()
+          .forEach((e) => e.gameRef = gameRef);
+    }
+  }
 }

packages/flame/test/components/has_game_ref_test.dart

@@ -11,7 +11,7 @@ class MyGame extends BaseGame {
 
 class MyComponent extends PositionComponent with HasGameRef<MyGame> {
   void foo() {
-    gameRef!.foo();
+    gameRef.foo();
   }
 }