Implement global hotkey registration for Windows media key detection

.gitignore

@@ -49,3 +49,4 @@ app.*.map.json
 
 service-account.json
 .env
+_codeql_detected_source_root

media_key_detector/media_key_detector_windows/CHANGELOG.md

@@ -1,6 +1,9 @@
 # 0.0.2
 
-- TBD
+- Implement global media key detection using Windows RegisterHotKey API
+- Add event channel support for media key events
+- Media keys now work even when app is not focused
+- Improved error handling for hotkey registration
 
 # 0.0.1
 

media_key_detector/media_key_detector_windows/README.md

@@ -4,11 +4,52 @@
 
 The windows implementation of `media_key_detector`.
 
+## Features
+
+This plugin provides global media key detection on Windows using the Windows `RegisterHotKey` API. This allows your application to respond to media keys (play/pause, next track, previous track) even when it's not the focused application.
+
+### Supported Media Keys
+
+- Play/Pause (VK_MEDIA_PLAY_PAUSE)
+- Next Track (VK_MEDIA_NEXT_TRACK)
+- Previous Track (VK_MEDIA_PREV_TRACK)
+
+### Implementation Details
+
+The plugin uses:
+- `RegisterHotKey` Windows API for global hotkey registration
+- Event channels for communicating media key events to Dart
+- Window message handlers to process WM_HOTKEY messages
+
+Hotkeys are registered when `setIsPlaying(true)` is called and automatically unregistered when `setIsPlaying(false)` is called or when the plugin is destroyed.
+
 ## Usage
 
 This package is [endorsed][endorsed_link], which means you can simply use `media_key_detector`
 normally. This package will be automatically included in your app when you do.
 
+```dart
+import 'package:media_key_detector/media_key_detector.dart';
+
+// Enable media key detection
+mediaKeyDetector.setIsPlaying(isPlaying: true);
+
+// Listen for media key events
+mediaKeyDetector.addListener((MediaKey key) {
+  switch (key) {
+    case MediaKey.playPause:
+      // Handle play/pause
+      break;
+    case MediaKey.fastForward:
+      // Handle next track
+      break;
+    case MediaKey.rewind:
+      // Handle previous track
+      break;
+  }
+});
+```
+
 [endorsed_link]: https://flutter.dev/docs/development/packages-and-plugins/developing-packages#endorsed-federated-plugin
 [very_good_analysis_badge]: https://img.shields.io/badge/style-very_good_analysis-B22C89.svg
 [very_good_analysis_link]: https://pub.dev/packages/very_good_analysis

media_key_detector/media_key_detector_windows/lib/media_key_detector_windows.dart

@@ -5,6 +5,7 @@ import 'package:media_key_detector_platform_interface/media_key_detector_platfor
 /// The Windows implementation of [MediaKeyDetectorPlatform].
 class MediaKeyDetectorWindows extends MediaKeyDetectorPlatform {
   bool _isPlaying = false;
+  final _eventChannel = const EventChannel('media_key_detector_windows_events');
 
   /// The method channel used to interact with the native platform.
   @visibleForTesting
@@ -17,7 +18,16 @@ class MediaKeyDetectorWindows extends MediaKeyDetectorPlatform {
 
   @override
   void initialize() {
-    ServicesBinding.instance.keyboard.addHandler(defaultHandler);
+    _eventChannel.receiveBroadcastStream().listen((event) {
+      final keyIdx = event as int;
+      MediaKey? key;
+      if (keyIdx > -1 && keyIdx < MediaKey.values.length) {
+        key = MediaKey.values[keyIdx];
+      }
+      if (key != null) {
+        triggerListeners(key);
+      }
+    });
   }
 
   @override
@@ -27,11 +37,13 @@ class MediaKeyDetectorWindows extends MediaKeyDetectorPlatform {
 
   @override
   Future<bool> getIsPlaying() async {
-    return _isPlaying;
+    final isPlaying = await methodChannel.invokeMethod<bool>('getIsPlaying');
+    return isPlaying ?? _isPlaying;
   }
 
   @override
   Future<void> setIsPlaying({required bool isPlaying}) async {
     _isPlaying = isPlaying;
+    await methodChannel.invokeMethod<void>('setIsPlaying', <String, dynamic>{'isPlaying': isPlaying});
   }
 }

media_key_detector/media_key_detector_windows/windows/media_key_detector_windows_plugin.cpp

@@ -6,19 +6,27 @@
 #include <flutter/method_channel.h>
 #include <flutter/plugin_registrar_windows.h>
 #include <flutter/standard_method_codec.h>
+#include <flutter/event_channel.h>
+#include <flutter/event_stream_handler_functions.h>
 
 #include <map>
 #include <memory>
+#include <atomic>
 
 namespace {
 
 using flutter::EncodableValue;
 
+// Hotkey IDs for media keys
+constexpr int HOTKEY_PLAY_PAUSE = 1;
+constexpr int HOTKEY_NEXT_TRACK = 2;
+constexpr int HOTKEY_PREV_TRACK = 3;
+
 class MediaKeyDetectorWindows : public flutter::Plugin {
  public:
   static void RegisterWithRegistrar(flutter::PluginRegistrarWindows *registrar);
 
-  MediaKeyDetectorWindows();
+  MediaKeyDetectorWindows(flutter::PluginRegistrarWindows *registrar);
 
   virtual ~MediaKeyDetectorWindows();
 
@@ -27,6 +35,21 @@ class MediaKeyDetectorWindows : public flutter::Plugin {
   void HandleMethodCall(
       const flutter::MethodCall<flutter::EncodableValue> &method_call,
       std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
+
+  // Register global hotkeys for media keys
+  void RegisterHotkeys();
+
+  // Unregister global hotkeys
+  void UnregisterHotkeys();
+
+  // Handle Windows messages
+  std::optional<LRESULT> HandleWindowProc(HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam);
+
+  flutter::PluginRegistrarWindows *registrar_;
+  std::unique_ptr<flutter::EventSink<>> event_sink_;
+  std::atomic<bool> is_playing_{false};
+  int window_proc_id_ = -1;
+  bool hotkeys_registered_ = false;
 };
 
 // static
@@ -37,31 +60,151 @@ void MediaKeyDetectorWindows::RegisterWithRegistrar(
           registrar->messenger(), "media_key_detector_windows",
           &flutter::StandardMethodCodec::GetInstance());
 
-  auto plugin = std::make_unique<MediaKeyDetectorWindows>();
+  auto plugin = std::make_unique<MediaKeyDetectorWindows>(registrar);
 
   channel->SetMethodCallHandler(
       [plugin_pointer = plugin.get()](const auto &call, auto result) {
         plugin_pointer->HandleMethodCall(call, std::move(result));
       });
 
+  // Set up event channel for media key events
+  auto event_channel =
+      std::make_unique<flutter::EventChannel<flutter::EncodableValue>>(
+          registrar->messenger(), "media_key_detector_windows_events",
+          &flutter::StandardMethodCodec::GetInstance());
+
+  auto event_handler = std::make_unique<flutter::StreamHandlerFunctions<>>(
+      [plugin_pointer = plugin.get()](
+          const flutter::EncodableValue* arguments,
+          std::unique_ptr<flutter::EventSink<>>&& events)
+          -> std::unique_ptr<flutter::StreamHandlerError<>> {
+        plugin_pointer->event_sink_ = std::move(events);
+        return nullptr;
+      },
+      [plugin_pointer = plugin.get()](const flutter::EncodableValue* arguments)
+          -> std::unique_ptr<flutter::StreamHandlerError<>> {
+        plugin_pointer->event_sink_ = nullptr;
+        return nullptr;
+      });
+
+  event_channel->SetStreamHandler(std::move(event_handler));
+
   registrar->AddPlugin(std::move(plugin));
 }
 
-MediaKeyDetectorWindows::MediaKeyDetectorWindows() {}
+MediaKeyDetectorWindows::MediaKeyDetectorWindows(flutter::PluginRegistrarWindows *registrar) 
+    : registrar_(registrar) {
+  // Register a window procedure to handle hotkey messages
+  window_proc_id_ = registrar_->RegisterTopLevelWindowProcDelegate(
+      [this](HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
+        return HandleWindowProc(hwnd, message, wparam, lparam);
+      });
+}
 
-MediaKeyDetectorWindows::~MediaKeyDetectorWindows() {}
+MediaKeyDetectorWindows::~MediaKeyDetectorWindows() {
+  UnregisterHotkeys();
+  if (window_proc_id_ != -1) {
+    registrar_->UnregisterTopLevelWindowProcDelegate(window_proc_id_);
+  }
+}
 
 void MediaKeyDetectorWindows::HandleMethodCall(
     const flutter::MethodCall<flutter::EncodableValue> &method_call,
     std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
   if (method_call.method_name().compare("getPlatformName") == 0) {
     result->Success(EncodableValue("Windows"));
-  }
-  else {
+  } else if (method_call.method_name().compare("getIsPlaying") == 0) {
+    result->Success(EncodableValue(is_playing_.load()));
+  } else if (method_call.method_name().compare("setIsPlaying") == 0) {
+    const auto* arguments = std::get_if<flutter::EncodableMap>(method_call.arguments());
+    if (arguments) {
+      auto is_playing_it = arguments->find(EncodableValue("isPlaying"));
+      if (is_playing_it != arguments->end()) {
+        if (auto* is_playing = std::get_if<bool>(&is_playing_it->second)) {
+          is_playing_.store(*is_playing);
+          if (*is_playing) {
+            RegisterHotkeys();
+          } else {
+            UnregisterHotkeys();
+          }
+          result->Success();
+          return;
+        }
+      }
+    }
+    result->Error("INVALID_ARGUMENT", "isPlaying argument is required");
+  } else {
     result->NotImplemented();
   }
 }
 
+void MediaKeyDetectorWindows::RegisterHotkeys() {
+  if (hotkeys_registered_) {
+    return;
+  }
+
+  HWND hwnd = registrar_->GetView()->GetNativeWindow();
+
+  // Register global hotkeys for media keys
+  // MOD_NOREPEAT prevents the hotkey from repeating when held down
+  bool play_pause_ok = RegisterHotKey(hwnd, HOTKEY_PLAY_PAUSE, MOD_NOREPEAT, VK_MEDIA_PLAY_PAUSE);
+  bool next_ok = RegisterHotKey(hwnd, HOTKEY_NEXT_TRACK, MOD_NOREPEAT, VK_MEDIA_NEXT_TRACK);
+  bool prev_ok = RegisterHotKey(hwnd, HOTKEY_PREV_TRACK, MOD_NOREPEAT, VK_MEDIA_PREV_TRACK);
+
+  // If all registrations succeeded, mark as registered
+  // If any failed, unregister the successful ones to maintain consistent state
+  if (play_pause_ok && next_ok && prev_ok) {
+    hotkeys_registered_ = true;
+  } else {
+    // Clean up any successful registrations
+    if (play_pause_ok) UnregisterHotKey(hwnd, HOTKEY_PLAY_PAUSE);
+    if (next_ok) UnregisterHotKey(hwnd, HOTKEY_NEXT_TRACK);
+    if (prev_ok) UnregisterHotKey(hwnd, HOTKEY_PREV_TRACK);
+  }
+}
+
+void MediaKeyDetectorWindows::UnregisterHotkeys() {
+  if (!hotkeys_registered_) {
+    return;
+  }
+
+  HWND hwnd = registrar_->GetView()->GetNativeWindow();
+
+  UnregisterHotKey(hwnd, HOTKEY_PLAY_PAUSE);
+  UnregisterHotKey(hwnd, HOTKEY_NEXT_TRACK);
+  UnregisterHotKey(hwnd, HOTKEY_PREV_TRACK);
+
+  hotkeys_registered_ = false;
+}
+
+std::optional<LRESULT> MediaKeyDetectorWindows::HandleWindowProc(
+    HWND hwnd, UINT message, WPARAM wparam, LPARAM lparam) {
+  if (message == WM_HOTKEY && event_sink_) {
+    int key_index = -1;
+
+    // Map hotkey ID to media key index
+    switch (wparam) {
+      case HOTKEY_PLAY_PAUSE:
+        key_index = 0;  // MediaKey.playPause
+        break;
+      case HOTKEY_PREV_TRACK:
+        key_index = 1;  // MediaKey.rewind
+        break;
+      case HOTKEY_NEXT_TRACK:
+        key_index = 2;  // MediaKey.fastForward
+        break;
+    }
+
+    if (key_index >= 0) {
+      event_sink_->Success(EncodableValue(key_index));
+    }
+
+    return 0;
+  }
+
+  return std::nullopt;
+}
+
 }  // namespace
 
 void MediaKeyDetectorWindowsRegisterWithRegistrar(