flame/lib/game/widget_builder.dart

import 'package:flutter/widgets.dart';
import '../gestures.dart';
import 'embedded_game_widget.dart';
import 'game.dart';

class WidgetBuilder {
  Offset offset = Offset.zero;

  Widget build(Game game) {
    return GestureDetector(
      // Taps
      onTap: game is TapDetector ? () => (game as TapDetector).onTap() : null,
      onTapCancel: game is TapDetector ? () => (game as TapDetector).onTapCancel() : null,
      onTapDown:
          game is TapDetector ? (TapDownDetails d) => (game as TapDetector).onTapDown(d) : null,
      onTapUp: game is TapDetector ? (TapUpDetails d) => (game as TapDetector).onTapUp(d) : null,

      // Secondary taps
      onSecondaryTapDown: game is SecondaryTapDetector
          ? (TapDownDetails d) => (game as SecondaryTapDetector).onSecondaryTapDown(d)
          : null,
      onSecondaryTapUp: game is SecondaryTapDetector
          ? (TapUpDetails d) => (game as SecondaryTapDetector).onSecondaryTapUp(d)
          : null,
      onSecondaryTapCancel: game is SecondaryTapDetector
          ? () => (game as SecondaryTapDetector).onSecondaryTapCancel()
          : null,

      // Double tap
      onDoubleTap:
          game is DoubleTapDetector ? () => (game as DoubleTapDetector).onDoubleTap() : null,

      // Long presses
      onLongPress:
          game is LongPressDetector ? () => (game as LongPressDetector).onLongPress() : null,
      onLongPressStart: game is LongPressDetector
          ? (LongPressStartDetails d) => (game as LongPressDetector).onLongPressStart(d)
          : null,
      onLongPressMoveUpdate: game is LongPressDetector
          ? (LongPressMoveUpdateDetails d) => (game as LongPressDetector).onLongPressMoveUpdate(d)
          : null,
      onLongPressUp:
          game is LongPressDetector ? () => (game as LongPressDetector).onLongPressUp() : null,
      onLongPressEnd: game is LongPressDetector
          ? (LongPressEndDetails d) => (game as LongPressDetector).onLongPressEnd(d)
          : null,

      // Vertical drag
      onVerticalDragDown: game is VerticalDragDetector
          ? (DragDownDetails d) => (game as VerticalDragDetector).onVerticalDragDown(d)
          : null,
      onVerticalDragStart: game is VerticalDragDetector
          ? (DragStartDetails d) => (game as VerticalDragDetector).onVerticalDragStart(d)
          : null,
      onVerticalDragUpdate: game is VerticalDragDetector
          ? (DragUpdateDetails d) => (game as VerticalDragDetector).onVerticalDragUpdate(d)
          : null,
      onVerticalDragEnd: game is VerticalDragDetector
          ? (DragEndDetails d) => (game as VerticalDragDetector).onVerticalDragEnd(d)
          : null,
      onVerticalDragCancel: game is VerticalDragDetector
          ? () => (game as VerticalDragDetector).onVerticalDragCancel()
          : null,

      // Horizontal drag
      onHorizontalDragDown: game is HorizontalDragDetector
          ? (DragDownDetails d) => (game as HorizontalDragDetector).onHorizontalDragDown(d)
          : null,
      onHorizontalDragStart: game is HorizontalDragDetector
          ? (DragStartDetails d) => (game as HorizontalDragDetector).onHorizontalDragStart(d)
          : null,
      onHorizontalDragUpdate: game is HorizontalDragDetector
          ? (DragUpdateDetails d) => (game as HorizontalDragDetector).onHorizontalDragUpdate(d)
          : null,
      onHorizontalDragEnd: game is HorizontalDragDetector
          ? (DragEndDetails d) => (game as HorizontalDragDetector).onHorizontalDragEnd(d)
          : null,
      onHorizontalDragCancel: game is HorizontalDragDetector
          ? () => (game as HorizontalDragDetector).onHorizontalDragCancel()
          : null,

      // Force presses
      onForcePressStart: game is ForcePressDetector
          ? (ForcePressDetails d) => (game as ForcePressDetector).onForcePressStart(d)
          : null,
      onForcePressPeak: game is ForcePressDetector
          ? (ForcePressDetails d) => (game as ForcePressDetector).onForcePressPeak(d)
          : null,
      onForcePressUpdate: game is ForcePressDetector
          ? (ForcePressDetails d) => (game as ForcePressDetector).onForcePressUpdate(d)
          : null,
      onForcePressEnd: game is ForcePressDetector
          ? (ForcePressDetails d) => (game as ForcePressDetector).onForcePressEnd(d)
          : null,

      // Pan
      onPanDown:
          game is PanDetector ? (DragDownDetails d) => (game as PanDetector).onPanDown(d) : null,
      onPanStart:
          game is PanDetector ? (DragStartDetails d) => (game as PanDetector).onPanStart(d) : null,
      onPanUpdate: game is PanDetector
          ? (DragUpdateDetails d) => (game as PanDetector).onPanUpdate(d)
          : null,
      onPanEnd:
          game is PanDetector ? (DragEndDetails d) => (game as PanDetector).onPanEnd(d) : null,
      onPanCancel: game is PanDetector ? () => (game as PanDetector).onPanCancel() : null,

      // Scales
      onScaleStart: game is ScaleDetector
          ? (ScaleStartDetails d) => (game as ScaleDetector).onScaleStart(d)
          : null,
      onScaleUpdate: game is ScaleDetector
          ? (ScaleUpdateDetails d) => (game as ScaleDetector).onScaleUpdate(d)
          : null,
      onScaleEnd: game is ScaleDetector
          ? (ScaleEndDetails d) => (game as ScaleDetector).onScaleEnd(d)
          : null,

      child: Container(
          color: game.backgroundColor(),
          child: Directionality(textDirection: TextDirection.ltr, child: EmbeddedGameWidget(game))),
    );
  }
}

class OverlayGameWidget extends StatefulWidget {
  final Widget gameChild;
  final HasWidgetsOverlay game;

  OverlayGameWidget({Key key, this.gameChild, this.game}) : super(key: key);

  @override
  State<StatefulWidget> createState() => _OverlayGameWidgetState();
}

class _OverlayGameWidgetState extends State<OverlayGameWidget> {
  final Map<String, Widget> _overlays = {};

  @override
  void initState() {
    super.initState();
    widget.game.widgetOverlayController.stream.listen((overlay) {
      setState(() {
        if (overlay.widget == null) {
          _overlays.remove(overlay.name);
        } else {
          _overlays[overlay.name] = overlay.widget;
        }
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Directionality(
        textDirection: TextDirection.ltr,
        child: Stack(children: [widget.gameChild, ..._overlays.values.toList()]));
  }
}

class OverlayWidgetBuilder extends WidgetBuilder {
  OverlayWidgetBuilder();

  @override
  Widget build(Game game) {
    final container = super.build(game);

    return OverlayGameWidget(gameChild: container, game: game, key: UniqueKey());
  }
}