fix: Use ComponentKeys to keep track of dispatchers

packages/flame/lib/src/events/component_mixins/double_tap_callbacks.dart

@@ -30,8 +30,10 @@ mixin DoubleTapCallbacks on Component {
   void onMount() {
     super.onMount();
     final game = findGame()! as FlameGame;
-    if (game.firstChild<DoubleTapDispatcher>() == null) {
-      game.add(DoubleTapDispatcher());
+    if (game.findByKey(const DoubleTapDispatcherKey()) == null) {
+      final dispatcher = DoubleTapDispatcher();
+      game.registerKey(const DoubleTapDispatcherKey(), dispatcher);
+      game.add(dispatcher);
     }
   }
 }

packages/flame/lib/src/events/component_mixins/drag_callbacks.dart

@@ -67,8 +67,10 @@ mixin DragCallbacks on Component {
   void onMount() {
     super.onMount();
     final game = findGame()! as FlameGame;
-    if (game.firstChild<MultiDragDispatcher>() == null) {
-      game.add(MultiDragDispatcher());
+    if (game.findByKey(const MultiDragDispatcherKey()) == null) {
+      final dispatcher = MultiDragDispatcher();
+      game.registerKey(const MultiDragDispatcherKey(), dispatcher);
+      game.add(dispatcher);
     }
   }
 }

packages/flame/lib/src/events/component_mixins/tap_callbacks.dart

@@ -24,8 +24,10 @@ mixin TapCallbacks on Component {
   void onMount() {
     super.onMount();
     final game = findGame()! as FlameGame;
-    if (game.firstChild<MultiTapDispatcher>() == null) {
-      game.add(MultiTapDispatcher());
+    if (game.findByKey(const MultiTapDispatcherKey()) == null) {
+      final dispatcher = MultiTapDispatcher();
+      game.registerKey(const MultiTapDispatcherKey(), dispatcher);
+      game.add(dispatcher);
     }
   }
 }

packages/flame/lib/src/events/flame_game_mixins/double_tap_dispatcher.dart

@@ -7,14 +7,25 @@ import 'package:flame/src/events/messages/double_tap_event.dart';
 import 'package:flutter/gestures.dart';
 import 'package:meta/meta.dart';
 
+@internal
+class DoubleTapDispatcherKey implements ComponentKey {
+  const DoubleTapDispatcherKey();
+
+  @override
+  int get hashCode => 20260645; // 'DoubleTapDispatcherKey' as hashCode
+
+  @override
+  bool operator ==(dynamic other) =>
+      other is DoubleTapDispatcherKey && other.hashCode == hashCode;
+}
+
 /// [DoubleTapDispatcher] propagates double-tap events to every components in
 /// the component tree that is mixed with [DoubleTapCallbacks]. This will be
 /// attached to the [FlameGame] instance automatically whenever any
 /// [DoubleTapCallbacks] are mounted into the component tree.
 @internal
 class DoubleTapDispatcher extends Component with HasGameRef<FlameGame> {
   final _components = <DoubleTapCallbacks>{};
-  bool _eventHandlerRegistered = false;
 
   void _onDoubleTapDown(DoubleTapDownEvent event) {
     event.deliverAtPoint(
@@ -37,30 +48,21 @@ class DoubleTapDispatcher extends Component with HasGameRef<FlameGame> {
 
   @override
   void onMount() {
-    if (game.firstChild<DoubleTapDispatcher>() == null) {
-      game.gestureDetectors.add(
-        DoubleTapGestureRecognizer.new,
-        (DoubleTapGestureRecognizer instance) {
-          instance.onDoubleTapDown =
-              (details) => _onDoubleTapDown(DoubleTapDownEvent(game, details));
-          instance.onDoubleTapCancel =
-              () => _onDoubleTapCancel(DoubleTapCancelEvent());
-          instance.onDoubleTap = () => _onDoubleTapUp(DoubleTapEvent());
-        },
-      );
-      _eventHandlerRegistered = true;
-    } else {
-      removeFromParent();
-    }
+    game.gestureDetectors.add(
+      DoubleTapGestureRecognizer.new,
+      (DoubleTapGestureRecognizer instance) {
+        instance.onDoubleTapDown =
+            (details) => _onDoubleTapDown(DoubleTapDownEvent(game, details));
+        instance.onDoubleTapCancel =
+            () => _onDoubleTapCancel(DoubleTapCancelEvent());
+        instance.onDoubleTap = () => _onDoubleTapUp(DoubleTapEvent());
+      },
+    );
   }
 
   @override
   void onRemove() {
-    if (!_eventHandlerRegistered) {
-      return;
-    }
-
     game.gestureDetectors.remove<DoubleTapGestureRecognizer>();
-    _eventHandlerRegistered = false;
+    game.unregisterKey(const DoubleTapDispatcherKey());
   }
 }

packages/flame/lib/src/events/flame_game_mixins/has_draggable_components.dart

@@ -1,4 +1,5 @@
 import 'package:flame/src/components/core/component.dart';
+import 'package:flame/src/components/core/component_key.dart';
 import 'package:flame/src/components/mixins/draggable.dart';
 import 'package:flame/src/events/component_mixins/drag_callbacks.dart';
 import 'package:flame/src/events/flame_drag_adapter.dart';
@@ -14,6 +15,18 @@ import 'package:flame/src/game/game_render_box.dart';
 import 'package:flutter/gestures.dart';
 import 'package:meta/meta.dart';
 
+@internal
+class MultiDragDispatcherKey implements ComponentKey {
+  const MultiDragDispatcherKey();
+
+  @override
+  int get hashCode => 91604879; // 'MultiDragDispatcherKey' as hashCode
+
+  @override
+  bool operator ==(dynamic other) =>
+      other is MultiDragDispatcherKey && other.hashCode == hashCode;
+}
+
 /// **MultiDragDispatcher** facilitates dispatching of drag events to the
 /// [DragCallbacks] components in the component tree. It will be attached to
 /// the [FlameGame] instance automatically whenever any [DragCallbacks]
@@ -22,7 +35,6 @@ import 'package:meta/meta.dart';
 class MultiDragDispatcher extends Component implements MultiDragListener {
   /// The record of all components currently being touched.
   final Set<TaggedComponent<DragCallbacks>> _records = {};
-  bool _eventHandlerRegistered = false;
 
   FlameGame get game => parent! as FlameGame;
 
@@ -165,26 +177,18 @@ class MultiDragDispatcher extends Component implements MultiDragListener {
 
   @override
   void onMount() {
-    if (game.firstChild<MultiDragDispatcher>() == null) {
-      game.gestureDetectors.add<ImmediateMultiDragGestureRecognizer>(
-        ImmediateMultiDragGestureRecognizer.new,
-        (ImmediateMultiDragGestureRecognizer instance) {
-          instance.onStart = (Offset point) => FlameDragAdapter(this, point);
-        },
-      );
-      _eventHandlerRegistered = true;
-    } else {
-      // Ensures that only one MultiDragDispatcher is attached to the Game.
-      removeFromParent();
-    }
+    game.gestureDetectors.add<ImmediateMultiDragGestureRecognizer>(
+      ImmediateMultiDragGestureRecognizer.new,
+      (ImmediateMultiDragGestureRecognizer instance) {
+        instance.onStart = (Offset point) => FlameDragAdapter(this, point);
+      },
+    );
   }
 
   @override
   void onRemove() {
-    if (_eventHandlerRegistered) {
-      game.gestureDetectors.remove<ImmediateMultiDragGestureRecognizer>();
-      _eventHandlerRegistered = false;
-    }
+    game.gestureDetectors.remove<ImmediateMultiDragGestureRecognizer>();
+    game.unregisterKey(const MultiDragDispatcherKey());
   }
 
   @override

packages/flame/lib/src/events/flame_game_mixins/has_tappable_components.dart

@@ -11,11 +11,22 @@ import 'package:flame/src/game/game_render_box.dart';
 import 'package:flutter/gestures.dart';
 import 'package:meta/meta.dart';
 
+@internal
+class MultiTapDispatcherKey implements ComponentKey {
+  const MultiTapDispatcherKey();
+
+  @override
+  int get hashCode => 401913931; // 'MultiTapDispatcherKey' as hashCode
+
+  @override
+  bool operator ==(dynamic other) =>
+      other is MultiTapDispatcherKey && other.hashCode == hashCode;
+}
+
 @internal
 class MultiTapDispatcher extends Component implements MultiTapListener {
   /// The record of all components currently being touched.
   final Set<TaggedComponent<TapCallbacks>> _record = {};
-  bool _eventHandlerRegistered = false;
 
   FlameGame get game => parent! as FlameGame;
 
@@ -179,33 +190,25 @@ class MultiTapDispatcher extends Component implements MultiTapListener {
 
   @override
   void onMount() {
-    if (game.firstChild<MultiTapDispatcher>() == null) {
-      game.gestureDetectors.add<MultiTapGestureRecognizer>(
-        MultiTapGestureRecognizer.new,
-        (MultiTapGestureRecognizer instance) {
-          instance.longTapDelay = Duration(
-            milliseconds: (longTapDelay * 1000).toInt(),
-          );
-          instance.onTap = handleTap;
-          instance.onTapDown = handleTapDown;
-          instance.onTapUp = handleTapUp;
-          instance.onTapCancel = handleTapCancel;
-          instance.onLongTapDown = handleLongTapDown;
-        },
-      );
-      _eventHandlerRegistered = true;
-    } else {
-      // Ensures that only one MultiTapDispatcher is attached to the Game.
-      removeFromParent();
-    }
+    game.gestureDetectors.add<MultiTapGestureRecognizer>(
+      MultiTapGestureRecognizer.new,
+      (MultiTapGestureRecognizer instance) {
+        instance.longTapDelay = Duration(
+          milliseconds: (longTapDelay * 1000).toInt(),
+        );
+        instance.onTap = handleTap;
+        instance.onTapDown = handleTapDown;
+        instance.onTapUp = handleTapUp;
+        instance.onTapCancel = handleTapCancel;
+        instance.onLongTapDown = handleLongTapDown;
+      },
+    );
   }
 
   @override
   void onRemove() {
-    if (_eventHandlerRegistered) {
-      game.gestureDetectors.remove<MultiTapGestureRecognizer>();
-      _eventHandlerRegistered = false;
-    }
+    game.gestureDetectors.remove<MultiTapGestureRecognizer>();
+    game.unregisterKey(const MultiTapDispatcherKey());
   }
 
   @override