refactor: ball layer and ramp addAll components

lib/game/components/ball.dart

@@ -8,12 +8,9 @@ import 'package:pinball/game/game.dart';
 /// {@endtemplate}
 class Ball extends BodyComponent<PinballGame> with InitialPosition, Layered {
   /// {@macro ball}
-  Ball({
-    Layer? layer,
-  }) : _layer = layer ?? Layer.board;
-
-  /// [Layer] of the board that the [Ball] will interact with.
-  final Layer _layer;
+  Ball() {
+    layer = Layer.board;
+  }
 
   /// The size of the [Ball]
   final Vector2 size = Vector2.all(2);
@@ -41,9 +38,7 @@ class Ball extends BodyComponent<PinballGame> with InitialPosition, Layered {
   Body createBody() {
     final shape = CircleShape()..radius = size.x / 2;
 
-    final fixtureDef = FixtureDef(shape)
-      ..density = 1
-      ..filter.maskBits = _layer.maskBits;
+    final fixtureDef = FixtureDef(shape)..density = 1;
 
     final bodyDef = BodyDef()
       ..position = initialPosition

lib/game/components/jetpack_ramp.dart

@@ -23,36 +23,39 @@ class JetpackRamp extends Component with HasGameRef<PinballGame> {
   /// The position of this [JetpackRamp]
   final Vector2 position;
 
+  static const _layer = Layer.jetpack;
+
   @override
   Future<void> onLoad() async {
-    await add(
-      Pathway.arc(
+    gameRef.addContactCallback(
+      RampOpeningBallContactCallback<JetpackRampOpening>(),
+    );
+
+    final curvePath = Pathway.arc(
+      // TODO(ruialonso): Remove color when not needed.
+      // TODO(ruialonso): Use a bezier curve once control points are defined.
       color: const Color.fromARGB(255, 8, 218, 241),
       center: position,
       width: _width,
       radius: _radius,
       angle: _angle,
       rotation: _rotation,
-        layer: Layer.jetpack,
-      )..initialPosition = position,
-    );
-
-    await add(
-      JetpackRampOpening(
+      layer: _layer,
+    )..initialPosition = position;
+    final leftOpening = JetpackRampOpening(
       orientation: RampOrientation.down,
       rotation: radians(15),
-      )..initialPosition = position + Vector2(-11, 1),
-    );
-    await add(
-      JetpackRampOpening(
+    )..initialPosition = position + Vector2(-11, 1);
+    final rightOpening = JetpackRampOpening(
       orientation: RampOrientation.down,
       rotation: radians(-9),
-      )..initialPosition = position + Vector2(20.5, 3.4),
-    );
+    )..initialPosition = position + Vector2(20.5, 3.4);
 
-    gameRef.addContactCallback(
-      RampOpeningBallContactCallback<JetpackRampOpening>(),
-    );
+    await addAll([
+      curvePath,
+      leftOpening,
+      rightOpening,
+    ]);
   }
 }
 

lib/game/components/launcher_ramp.dart

@@ -26,41 +26,39 @@ class LauncherRamp extends Component with HasGameRef<PinballGame> {
 
   @override
   Future<void> onLoad() async {
-    await add(
-      Pathway.straight(
+    gameRef.addContactCallback(
+      RampOpeningBallContactCallback<LauncherRampOpening>(),
+    );
+
+    final straightPath = Pathway.straight(
       color: const Color.fromARGB(255, 34, 255, 0),
       start: Vector2(0, 0),
       end: Vector2(0, 600),
       width: 80,
       layer: Layer.launcher,
-      )..initialPosition = position,
-    );
-
-    await add(
-      Pathway.arc(
+    )..initialPosition = position;
+    final curvedPath = Pathway.arc(
       color: const Color.fromARGB(255, 251, 255, 0),
       center: position + Vector2(-28.8, -6),
       radius: _radius,
       angle: _angle,
       width: _width,
       layer: Layer.launcher,
-      )..initialPosition = position + Vector2(-28.8, -6),
-    );
-    await add(
-      LauncherRampOpening(
+    )..initialPosition = position + Vector2(-28.8, -6);
+    final leftOpening = LauncherRampOpening(
       orientation: RampOrientation.down,
       rotation: radians(13),
-      )..initialPosition = position + Vector2(-46.5, -8.5),
-    );
-    await add(
-      LauncherRampOpening(
+    )..initialPosition = position + Vector2(-46.5, -8.5);
+    final rightOpening = LauncherRampOpening(
       orientation: RampOrientation.down,
-      )..initialPosition = position + Vector2(4, 0),
-    );
+    )..initialPosition = position + Vector2(4, 0);
 
-    gameRef.addContactCallback(
-      RampOpeningBallContactCallback<LauncherRampOpening>(),
-    );
+    await addAll([
+      straightPath,
+      curvedPath,
+      leftOpening,
+      rightOpening,
+    ]);
   }
 }
 

lib/game/components/layer.dart

@@ -11,8 +11,17 @@ import 'package:pinball/game/game.dart';
 /// bodies with a different bit value.
 /// {@endtemplate}
 mixin Layered<T extends Forge2DGame> on BodyComponent<T> {
-  /// Sets [Filter] category and mask bits for the [BodyComponent]
-  set layer(Layer layer) {
+  Layer _layer = Layer.board;
+
+  /// Sets [Filter] category and mask bits for the [BodyComponent].
+  Layer get layer => _layer;
+
+  set layer(Layer value) {
+    _layer = value;
+    if (!isLoaded) {
+      // TODO(erickzanardo): Use loaded.whenComplete once provided.
+      mounted.whenComplete(() => layer = value);
+    } else {
       for (final fixture in body.fixtures) {
         fixture
           ..filterData.categoryBits = layer.maskBits
@@ -20,6 +29,7 @@ mixin Layered<T extends Forge2DGame> on BodyComponent<T> {
       }
     }
   }
+}
 
 /// Indicates the type of a layer.
 ///