fix: Allow most basic and advanced gesture detectors together (#1208)

Most gesture detectors work together now, except for the PanDetector or ScaleDetector together with the MultiTouchDragDetector. Maybe even the ScaleDetector will work with the MultiTouchDragDetector, will have to try.

packages/flame/example/lib/main.dart

@@ -14,14 +14,51 @@ void main() {
   );
 }
 
-class Square extends PositionComponent {
+/// This example simply adds a rotating white square on the screen, if you press
+/// somewhere other than on the existing square another square will be added and
+/// if you press on a square it will be removed.
+class MyGame extends FlameGame with DoubleTapDetector, HasTappables {
+  bool running = true;
+
+  @override
+  Future<void> onLoad() async {
+    await super.onLoad();
+    add(Square(Vector2(100, 200)));
+  }
+
+  @override
+  void onTapUp(int id, TapUpInfo info) {
+    super.onTapUp(id, info);
+    final touchPoint = info.eventPosition.game;
+    final handled = children.any((c) => c.shouldRemove);
+
+    if (!handled) {
+      add(Square(touchPoint));
+    }
+  }
+
+  @override
+  void onDoubleTap() {
+    if (running) {
+      pauseEngine();
+    } else {
+      resumeEngine();
+    }
+
+    running = !running;
+  }
+}
+
+class Square extends PositionComponent with Tappable {
   static const speed = 0.25;
   static const squareSize = 128.0;
 
   static Paint white = BasicPalette.white.paint();
   static Paint red = BasicPalette.red.paint();
   static Paint blue = BasicPalette.blue.paint();
 
+  Square(Vector2 position) : super(position: position);
+
   @override
   void render(Canvas c) {
     c.drawRect(size.toRect(), white);
@@ -42,46 +79,10 @@ class Square extends PositionComponent {
     size.setValues(squareSize, squareSize);
     anchor = Anchor.center;
   }
-}
-
-class MyGame extends FlameGame with DoubleTapDetector, TapDetector {
-  bool running = true;
 
   @override
-  Future<void> onLoad() async {
-    await super.onLoad();
-    add(
-      Square()
-        ..x = 100
-        ..y = 100,
-    );
-  }
-
-  @override
-  void onTapUp(TapUpInfo info) {
-    final touchPoint = info.eventPosition.game;
-
-    final handled = children.any((c) {
-      if (c is PositionComponent && c.containsPoint(touchPoint)) {
-        remove(c);
-        return true;
-      }
-      return false;
-    });
-
-    if (!handled) {
-      add(Square()..position = touchPoint);
-    }
-  }
-
-  @override
-  void onDoubleTap() {
-    if (running) {
-      pauseEngine();
-    } else {
-      resumeEngine();
-    }
-
-    running = !running;
+  bool onTapUp(TapUpInfo info) {
+    removeFromParent();
+    return true;
   }
 }

packages/flame/example/pubspec.yaml

@@ -1,9 +1,7 @@
 name: flame_example
 description: Simple example of a Flame game
-
-publish_to: 'none'
-
 version: 0.1.0
+publish_to: 'none'
 
 environment:
   sdk: ">=2.14.0 <3.0.0"

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

@@ -61,6 +61,7 @@ mixin Tappable on Component {
   }
 }
 
+// TODO(spydon): these methods should return the result of propagateToChildren.
 mixin HasTappables on FlameGame {
   @mustCallSuper
   void onTapCancel(int pointerId) {

packages/flame/lib/src/game/game_widget/game_widget.dart

@@ -264,34 +264,33 @@ class _GameWidgetState<T extends Game> extends State<GameWidget<T>> {
 
   @override
   Widget build(BuildContext context) {
-    Widget internalGameWidget = _GameRenderObjectWidget(widget.game);
-
-    final hasBasicDetectors = hasBasicGestureDetectors(widget.game);
-    final hasAdvancedDetectors = hasAdvancedGesturesDetectors(widget.game);
+    final game = widget.game;
+    Widget internalGameWidget = _GameRenderObjectWidget(game);
 
     assert(
-      !(hasBasicDetectors && hasAdvancedDetectors),
-      '''
-        WARNING: Both Advanced and Basic detectors detected.
-        Advanced detectors will override basic detectors and the later will not receive events
-      ''',
+      !(game is MultiTouchDragDetector && game is PanDetector),
+      'WARNING: Both MultiTouchDragDetector and a PanDetector detected. '
+      'The MultiTouchDragDetector will override the PanDetector and it will '
+      'not receive events',
     );
 
-    if (hasBasicDetectors) {
+    if (hasBasicGestureDetectors(game)) {
       internalGameWidget = applyBasicGesturesDetectors(
-        widget.game,
+        game,
         internalGameWidget,
       );
-    } else if (hasAdvancedDetectors) {
+    }
+
+    if (hasAdvancedGestureDetectors(game)) {
       internalGameWidget = applyAdvancedGesturesDetectors(
-        widget.game,
+        game,
         internalGameWidget,
       );
     }
 
-    if (hasMouseDetectors(widget.game)) {
+    if (hasMouseDetectors(game)) {
       internalGameWidget = applyMouseDetectors(
-        widget.game,
+        game,
         internalGameWidget,
       );
     }
@@ -312,10 +311,10 @@ class _GameWidgetState<T extends Game> extends State<GameWidget<T>> {
         child: Directionality(
           textDirection: textDir,
           child: Container(
-            color: widget.game.backgroundColor(),
+            color: game.backgroundColor(),
             child: LayoutBuilder(
               builder: (_, BoxConstraints constraints) {
-                widget.game.onGameResize(constraints.biggest.toVector2());
+                game.onGameResize(constraints.biggest.toVector2());
                 return FutureBuilder(
                   future: loaderFuture,
                   builder: (_, snapshot) {

packages/flame/lib/src/game/game_widget/gestures.dart

@@ -7,27 +7,30 @@ import '../../gestures/detectors.dart';
 import '../../gestures/events.dart';
 import '../mixins/game.dart';
 
-bool hasBasicGestureDetectors(Game game) =>
-    game is TapDetector ||
-    game is SecondaryTapDetector ||
-    game is DoubleTapDetector ||
-    game is LongPressDetector ||
-    game is VerticalDragDetector ||
-    game is HorizontalDragDetector ||
-    game is ForcePressDetector ||
-    game is PanDetector ||
-    game is ScaleDetector;
+bool hasBasicGestureDetectors(Game game) {
+  return game is TapDetector ||
+      game is SecondaryTapDetector ||
+      game is DoubleTapDetector ||
+      game is LongPressDetector ||
+      game is VerticalDragDetector ||
+      game is HorizontalDragDetector ||
+      game is ForcePressDetector ||
+      game is PanDetector ||
+      game is ScaleDetector;
+}
 
-bool hasAdvancedGesturesDetectors(Game game) =>
-    game is MultiTouchTapDetector ||
-    game is MultiTouchDragDetector ||
-    game is HasTappables ||
-    game is HasDraggables;
+bool hasAdvancedGestureDetectors(Game game) {
+  return game is MultiTouchTapDetector ||
+      game is MultiTouchDragDetector ||
+      game is HasTappables ||
+      game is HasDraggables;
+}
 
-bool hasMouseDetectors(Game game) =>
-    game is MouseMovementDetector ||
-    game is ScrollDetector ||
-    game is HasHoverables;
+bool hasMouseDetectors(Game game) {
+  return game is MouseMovementDetector ||
+      game is ScrollDetector ||
+      game is HasHoverables;
+}
 
 Widget applyBasicGesturesDetectors(Game game, Widget child) {
   return GestureDetector(

packages/flame/test/game/detectors_test.dart

@@ -0,0 +1,37 @@
+import 'package:flame/game.dart';
+import 'package:flame/input.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+class _MultiDragPanGame extends FlameGame
+    with MultiTouchDragDetector, PanDetector {}
+
+class _MultiTapDoubleTapGame extends FlameGame
+    with MultiTouchTapDetector, DoubleTapDetector {}
+
+void main() {
+  group('apply detectors', () {
+    testWidgets(
+      'game can not have both MultiTouchDragDetector and PanDetector',
+      (tester) async {
+        await tester.pumpWidget(
+          GameWidget(
+            game: _MultiDragPanGame(),
+          ),
+        );
+        expect(tester.takeException(), isInstanceOf<AssertionError>());
+      },
+    );
+
+    testWidgets(
+      'game can have both MultiTouchTapDetector and DoubleTapDetector',
+      (tester) async {
+        await tester.pumpWidget(
+          GameWidget(
+            game: _MultiTapDoubleTapGame(),
+          ),
+        );
+        expect(tester.takeException(), null);
+      },
+    );
+  });
+}