feat: implemented FlipperAnchor

lib/game/components/flipper.dart

@@ -5,6 +5,11 @@ import 'package:flame_forge2d/flame_forge2d.dart';
 import 'package:flutter/material.dart';
 import 'package:pinball/game/game.dart';
 
+enum FlipperType {
+  left,
+  right,
+}
+
 /// {@template flipper}
 /// A bat, typically found in pairs at the bottom of the board.
 ///
@@ -12,11 +17,11 @@ import 'package:pinball/game/game.dart';
 /// {@endtemplate flipper}
 class Flipper extends BodyComponent {
   /// {@macro flipper}
-  Flipper._({
+  Flipper({
     required Vector2 position,
-    bool isMirrored = false,
+    required this.type,
   })  : _position = position,
-        _isMirrored = isMirrored,
+        _isMirrored = type == FlipperType.left,
         _speed = _calculateSpeed() {
     // TODO(alestiago): Use sprite instead of color when provided.
     paint = Paint()
@@ -24,22 +29,6 @@ class Flipper extends BodyComponent {
       ..style = PaintingStyle.fill;
   }
 
-  /// {@macro flipper}
-  Flipper.right({
-    required Vector2 position,
-  }) : this._(
-          position: position,
-          isMirrored: true,
-        );
-
-  /// {@macro flipper}
-  Flipper.left({
-    required Vector2 position,
-  }) : this._(
-          position: position,
-          isMirrored: false,
-        );
-
   /// The width of the [Flipper].
   static const width = 12.0;
 
@@ -75,6 +64,8 @@ class Flipper extends BodyComponent {
   /// The initial position of the [Flipper] body.
   final Vector2 _position;
 
+  final FlipperType type;
+
   /// Whether the [Flipper] is mirrored.
   ///
   /// A mirrored [Flipper] is one positioned at the right of the borad.
@@ -160,8 +151,21 @@ class Flipper extends BodyComponent {
   }
 }
 
+class FlipperAnchor extends Anchor {
+  FlipperAnchor({
+    required Flipper flipper,
+  }) : super(
+          position: Vector2(
+            flipper.type == FlipperType.left
+                ? flipper.body.position.x
+                : flipper.body.position.x + Flipper.width,
+            flipper.body.position.y - Flipper.height / 2,
+          ),
+        );
+}
+
 /// {@template flipper_anchor_revolute_joint_def}
-/// Hinges one end of [Flipper] to an [Anchor] to achieve an arc motion.
+/// Hinges one end of [Flipper] to a [Anchor] to achieve an arc motion.
 /// {@endtemplate}
 class FlipperAnchorRevoluteJointDef extends RevoluteJointDef {
   /// {@macro flipper_anchor_revolute_joint_def}

lib/game/pinball_game.dart

@@ -35,19 +35,15 @@ class PinballGame extends Forge2DGame with FlameBloc, KeyboardEvents {
     final center = screenToWorld(camera.viewport.effectiveSize / 2);
     const flipperSpace = 2;
     await add(
-      _leftFlipper = Flipper.left(
+      _leftFlipper = Flipper(
         position: Vector2(
           (center.x - (Flipper.width / 2)) - (flipperSpace / 2),
           center.y,
         ),
+        type: FlipperType.left,
       ),
     );
-    final leftFlipperAnchor = Anchor(
-      position: Vector2(
-        _leftFlipper.body.position.x,
-        _leftFlipper.body.position.y - Flipper.height / 2,
-      ),
-    );
+    final leftFlipperAnchor = FlipperAnchor(flipper: _leftFlipper);
     await add(leftFlipperAnchor);
     final leftFlipperRevoluteJointDef = FlipperAnchorRevoluteJointDef(
       flipper: _leftFlipper,
@@ -59,19 +55,15 @@ class PinballGame extends Forge2DGame with FlameBloc, KeyboardEvents {
         world.createJoint(leftFlipperRevoluteJointDef) as RevoluteJoint;
 
     await add(
-      _rightFlipper = Flipper.right(
+      _rightFlipper = Flipper(
         position: Vector2(
           (center.x + (Flipper.width / 2)) + (flipperSpace / 2),
           center.y,
         ),
+        type: FlipperType.right,
       ),
     );
-    final rightFlipperAnchor = Anchor(
-      position: Vector2(
-        _rightFlipper.body.position.x + Flipper.width,
-        _rightFlipper.body.position.y - Flipper.height / 2,
-      ),
-    );
+    final rightFlipperAnchor = FlipperAnchor(flipper: _rightFlipper);
     await add(rightFlipperAnchor);
     final rightFlipperRevoluteJointDef = FlipperAnchorRevoluteJointDef(
       flipper: _rightFlipper,