feat: Added GamepadState that can be updated (#43)

packages/gamepads/example/lib/main.dart

@@ -96,8 +96,13 @@ class _MyHomePageState extends State<MyHomePage> {
             const Text('Gamepads:'),
             if (loading)
               const CircularProgressIndicator()
-            else
-              ..._gamepads.map((e) => Text('${e.id} - ${e.name}')),
+            else ...[
+              for (final gamepad in _gamepads) ...[
+                Text('${gamepad.id} - ${gamepad.name}'),
+                Text('  Analog inputs: ${gamepad.state.analogInputs}'),
+                Text('  Button inputs: ${gamepad.state.buttonInputs}'),
+              ],
+            ],
           ],
         ),
       ),

packages/gamepads_platform_interface/lib/api/gamepad_controller.dart

@@ -1,4 +1,14 @@
+import 'dart:async';
+
+import 'package:gamepads_platform_interface/api/gamepad_event.dart';
+import 'package:gamepads_platform_interface/api/gamepad_state.dart';
+import 'package:gamepads_platform_interface/gamepads_platform_interface.dart';
+
 /// Represents a single, currently connected joystick controller (or gamepad).
+///
+/// By calling the constructor, this object will automatically subscribe to
+/// events and update its internal [state]. To stop listening, be sure to call
+/// [dispose]. Failing to do so may result in the object leaking memory.
 class GamepadController {
   /// A unique identifier for the gamepad controller.
   ///
@@ -9,14 +19,30 @@ class GamepadController {
   /// A user-facing, platform-dependant name for the gamepad controller.
   final String name;
 
+  final state = GamepadState();
+
+  StreamSubscription<GamepadEvent>? _subscription;
+
   GamepadController({
     required this.id,
     required this.name,
-  });
+    required GamepadsPlatformInterface plugin,
+  }) {
+    _subscription = plugin.eventsByGamepad(id).listen(state.update);
+  }
 
-  factory GamepadController.parse(Map<dynamic, dynamic> map) {
+  factory GamepadController.parse(
+    Map<dynamic, dynamic> map,
+    GamepadsPlatformInterface plugin,
+  ) {
     final id = map['id'] as String;
     final name = map['name'] as String;
-    return GamepadController(id: id, name: name);
+    return GamepadController(id: id, name: name, plugin: plugin);
+  }
+
+  /// Stops listening for new inputs.
+  Future<void> dispose() async {
+    await _subscription?.cancel();
+    _subscription = null;
   }
 }

packages/gamepads_platform_interface/lib/api/gamepad_state.dart

@@ -0,0 +1,27 @@
+import 'package:gamepads_platform_interface/api/gamepad_event.dart';
+
+/// The current state of a gamepad.
+///
+/// This class keeps mutable state and is intended to be kept up-to-date by
+/// calling [update] with the latest [GamepadEvent]. The [analogInputs] and
+/// [buttonInputs] maps correspond to [KeyType.analog] and [KeyType.button],
+/// respectively.
+class GamepadState {
+  /// Contains inputs from events where [GamepadEvent.type] is [KeyType.analog].
+  final Map<String, double> analogInputs = {};
+
+  /// Contains inputs from events where [GamepadEvent.type] is [KeyType.button].
+  final Map<String, bool> buttonInputs = {};
+
+  /// Updates the state based on the given event.
+  void update(GamepadEvent event) {
+    switch (event.type) {
+      case KeyType.analog:
+        analogInputs[event.key] = event.value;
+        break;
+      case KeyType.button:
+        buttonInputs[event.key] = event.value == 1;
+        break;
+    }
+  }
+}

packages/gamepads_platform_interface/lib/gamepads_platform_interface.dart

@@ -20,4 +20,7 @@ abstract class GamepadsPlatformInterface extends PlatformInterface {
   Future<List<GamepadController>> listGamepads();
 
   Stream<GamepadEvent> get gamepadEventsStream;
+
+  Stream<GamepadEvent> eventsByGamepad(String gamepadId) =>
+      gamepadEventsStream.where((event) => event.gamepadId == gamepadId);
 }

packages/gamepads_platform_interface/lib/method_channel_gamepads_platform_interface.dart

@@ -21,7 +21,7 @@ class MethodChannelGamepadsPlatformInterface extends GamepadsPlatformInterface {
       <String, dynamic>{},
     );
     return result!.map((Object? e) {
-      return GamepadController.parse(e! as Map<dynamic, dynamic>);
+      return GamepadController.parse(e! as Map<dynamic, dynamic>, this);
     }).toList();
   }