feat: allowed progressing sprite

packages/pinball_components/lib/src/components/flutter_sign_post.dart

@@ -2,6 +2,33 @@ import 'package:flame/components.dart';
 import 'package:flame_forge2d/flame_forge2d.dart';
 import 'package:pinball_components/pinball_components.dart';
 
+enum _SignPostSpriteState {
+  inactive,
+  active1,
+  active2,
+  active3,
+}
+
+extension on _SignPostSpriteState {
+  String get path {
+    switch (this) {
+      case _SignPostSpriteState.inactive:
+        return Assets.images.signPost.inactive.keyName;
+      case _SignPostSpriteState.active1:
+        return Assets.images.signPost.active1.keyName;
+      case _SignPostSpriteState.active2:
+        return Assets.images.signPost.active2.keyName;
+      case _SignPostSpriteState.active3:
+        return Assets.images.signPost.active3.keyName;
+    }
+  }
+
+  _SignPostSpriteState get next {
+    return _SignPostSpriteState
+        .values[(index + 1) % _SignPostSpriteState.values.length];
+  }
+}
+
 /// {@template flutter_sign_post}
 /// A sign, found in the Flutter Forest.
 /// {@endtemplate}
@@ -15,6 +42,11 @@ class FlutterSignPost extends BodyComponent with InitialPosition {
     renderBody = false;
   }
 
+  /// Forwards the sprite to the next [_SignPostSpriteState].
+  ///
+  /// If the current state is the last one it goes back to the initial state.
+  void progress() => firstChild<_FlutterSignPostSpriteComponent>()!.progress();
+
   @override
   Body createBody() {
     final shape = CircleShape()..radius = 0.25;
@@ -27,17 +59,29 @@ class FlutterSignPost extends BodyComponent with InitialPosition {
   }
 }
 
-class _FlutterSignPostSpriteComponent extends SpriteComponent with HasGameRef {
+class _FlutterSignPostSpriteComponent
+    extends SpriteGroupComponent<_SignPostSpriteState> with HasGameRef {
+  _FlutterSignPostSpriteComponent()
+      : super(
+          anchor: Anchor.bottomCenter,
+          position: Vector2(0.65, 0.45),
+        );
+
+  void progress() => current = current?.next;
+
   @override
   Future<void> onLoad() async {
     await super.onLoad();
 
-    final sprite = await gameRef.loadSprite(
-      Assets.images.signPost.inactive.keyName,
+    final sprites = <_SignPostSpriteState, Sprite>{};
+    this.sprites = sprites;
+    for (final spriteState in _SignPostSpriteState.values) {
+      sprites[spriteState] = Sprite(
+        gameRef.images.fromCache(spriteState.path),
       );
-    this.sprite = sprite;
-    size = sprite.originalSize / 10;
-    anchor = Anchor.bottomCenter;
-    position = Vector2(0.65, 0.45);
+    }
+
+    current = _SignPostSpriteState.inactive;
+    size = sprites[current]!.originalSize / 10;
   }
 }