Bug 1575995 - part1 : implement basic classes for handling media hardware keys. r=baku

In order to receive platform level media hardward keys event, we create a `MediaHardwareKeysEventSource` which is used to implement intercepting those events according to different platforms.

We can add a `MediaHardwareKeysEventListener` onto `MediaHardwareKeysEventSource`, so that we can get notification whenever hardware media keys are being pressed.

`MediaHardwareKeysManager` is used to encapsulate all these details, it would create a source and corresponding listener.

Differential Revision: https://phabricator.services.mozilla.com/D43313

--HG--
extra : moz-landing-system : lando

dom/media/mediacontrol/MediaControlService.h

@@ -9,6 +9,7 @@
 
 #include "AudioFocusManager.h"
 #include "MediaController.h"
+#include "MediaHardwareKeysManager.h"
 #include "nsDataHashtable.h"
 #include "nsIObserver.h"
 #include "nsTArray.h"
@@ -55,6 +56,7 @@ class MediaControlService final : public nsIObserver {
 
   nsDataHashtable<nsUint64HashKey, RefPtr<MediaController>> mControllers;
   AudioFocusManager mAudioFocusManager;
+  MediaHardwareKeysManager mHardwareKeysManager;
 };
 
 }  // namespace dom

dom/media/mediacontrol/MediaHardwareKeysEvent.cpp

@@ -0,0 +1,83 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaHardwareKeysEvent.h"
+
+#include "MediaControlService.h"
+#include "mozilla/Logging.h"
+
+extern mozilla::LazyLogModule gMediaControlLog;
+
+// avoid redefined macro in unified build
+#undef LOG
+#define LOG(msg, ...)                        \
+  MOZ_LOG(gMediaControlLog, LogLevel::Debug, \
+          ("MediaHardwareKeysEventListener=%p, " msg, this, ##__VA_ARGS__))
+
+namespace mozilla {
+namespace dom {
+
+static const char* ToMediaControlKeysEventStr(MediaControlKeysEvent aKeyEvent) {
+  switch (aKeyEvent) {
+    case MediaControlKeysEvent::ePlayPause:
+      return "PlayPause";
+    case MediaControlKeysEvent::eNext:
+      return "Next";
+    case MediaControlKeysEvent::ePrev:
+      return "Prev";
+    default:
+      MOZ_ASSERT_UNREACHABLE("Invalid action.");
+  }
+  return "Unknown";
+}
+
+#undef LOG_KEY
+#define LOG_KEY(msg, key, ...)                                    \
+  if (MOZ_LOG_TEST(gMediaControlLog, mozilla::LogLevel::Debug)) { \
+    MOZ_LOG(gMediaControlLog, LogLevel::Debug,                    \
+            ("MediaHardwareKeysEventListener=%p, " msg, this,     \
+             ToMediaControlKeysEventStr(key), ##__VA_ARGS__));    \
+  }
+
+void MediaHardwareKeysEventListener::OnKeyPressed(
+    MediaControlKeysEvent aKeyEvent) {
+  LOG_KEY("OnKeyPressed '%s'", aKeyEvent);
+  switch (aKeyEvent) {
+    case MediaControlKeysEvent::ePlayPause:
+      // TODO : implement playing/pausing controller in following patch.
+      return;
+    case MediaControlKeysEvent::eNext:
+    case MediaControlKeysEvent::ePrev:
+      // TODO : implement related controller functions.
+      return;
+    default:
+      LOG("Error : undefined event!");
+      return;
+  }
+}
+
+void MediaHardwareKeysEventSource::AddListener(
+    MediaHardwareKeysEventListener* aListener) {
+  MOZ_ASSERT(aListener);
+  LOG("Add listener %p", aListener);
+  mListeners.AppendElement(aListener);
+}
+
+void MediaHardwareKeysEventSource::RemoveListener(
+    MediaHardwareKeysEventListener* aListener) {
+  MOZ_ASSERT(aListener);
+  LOG("Remove listener %p", aListener);
+  mListeners.RemoveElement(aListener);
+}
+
+size_t MediaHardwareKeysEventSource::GetListenersNum() const {
+  return mListeners.Length();
+}
+
+void MediaHardwareKeysEventSource::Close() { mListeners.Clear(); }
+
+}  // namespace dom
+}  // namespace mozilla

dom/media/mediacontrol/MediaHardwareKeysEvent.h

@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_mediahardwarekeysevent_h__
+#define mozilla_dom_mediahardwarekeysevent_h__
+
+#include "nsISupportsImpl.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace dom {
+
+enum class MediaControlKeysEvent { ePlayPause, ePrev, eNext, eNone };
+
+/**
+ * MediaHardwareKeysEventListener is used to monitor MediaControlKeysEvent, we
+ * can add it onto the MediaHardwareKeysEventSource, and then everytime when
+ * the media key events occur, `OnKeyPressed` will be called so that we can do
+ * related handling.
+ */
+class MediaHardwareKeysEventListener {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaHardwareKeysEventListener);
+  MediaHardwareKeysEventListener() = default;
+
+  virtual void OnKeyPressed(MediaControlKeysEvent aKeyEvent);
+
+ protected:
+  virtual ~MediaHardwareKeysEventListener() = default;
+};
+
+/**
+ * MediaHardwareKeysEventSource is a base class which is used to implement
+ * intercepting media hardware keys event per plaftform. When receiving media
+ * key events, it would notify all listeners which have been added onto the
+ * source.
+ */
+class MediaHardwareKeysEventSource {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaHardwareKeysEventSource);
+  MediaHardwareKeysEventSource() = default;
+
+  virtual void AddListener(MediaHardwareKeysEventListener* aListener);
+  virtual void RemoveListener(MediaHardwareKeysEventListener* aListener);
+  size_t GetListenersNum() const;
+  void Close();
+
+ protected:
+  virtual ~MediaHardwareKeysEventSource() = default;
+  nsTArray<RefPtr<MediaHardwareKeysEventListener>> mListeners;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif

dom/media/mediacontrol/MediaHardwareKeysManager.cpp

@@ -0,0 +1,49 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "MediaHardwareKeysManager.h"
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Logging.h"
+
+extern mozilla::LazyLogModule gMediaControlLog;
+
+#undef LOG
+#define LOG(msg, ...)                        \
+  MOZ_LOG(gMediaControlLog, LogLevel::Debug, \
+          ("MediaHardwareKeysManager=%p, " msg, this, ##__VA_ARGS__))
+
+namespace mozilla {
+namespace dom {
+
+MediaHardwareKeysManager::MediaHardwareKeysManager() {
+  StartMonitoringHardwareKeys();
+}
+
+MediaHardwareKeysManager::~MediaHardwareKeysManager() {
+  StopMonitoringHardwareKeys();
+}
+
+void MediaHardwareKeysManager::StartMonitoringHardwareKeys() {
+  LOG("StartMonitoringHardwareKeys");
+  CreateEventSource();
+  if (mEventSource) {
+    mEventSource->AddListener(new MediaHardwareKeysEventListener());
+  }
+}
+
+void MediaHardwareKeysManager::CreateEventSource() {
+  // TODO : create source per platform.
+}
+
+void MediaHardwareKeysManager::StopMonitoringHardwareKeys() {
+  LOG("StopMonitoringHardwareKeys");
+  if (mEventSource) {
+    mEventSource->Close();
+    mEventSource = nullptr;
+  }
+}
+
+}  // namespace dom
+}  // namespace mozilla

dom/media/mediacontrol/MediaHardwareKeysManager.h

@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_mediahardwarekeysobservice_h__
+#define mozilla_dom_mediahardwarekeysobservice_h__
+
+#include "MediaHardwareKeysEvent.h"
+
+namespace mozilla {
+namespace dom {
+
+/**
+ * MediaHardwareKeysManager is used to create a source to intercept platform
+ * level media keys event and assign a proper event listener to handle those
+ * events.
+ */
+class MediaHardwareKeysManager final {
+ public:
+  MediaHardwareKeysManager();
+  ~MediaHardwareKeysManager();
+
+  void StartMonitoringHardwareKeys();
+  void StopMonitoringHardwareKeys();
+
+ private:
+  void CreateEventSource();
+  RefPtr<MediaHardwareKeysEventSource> mEventSource;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif

dom/media/mediacontrol/moz.build

@@ -8,6 +8,8 @@ EXPORTS.mozilla.dom += [
     'MediaController.h',
     'MediaControlService.h',
     'MediaControlUtils.h',
+    'MediaHardwareKeysEvent.h',
+    'MediaHardwareKeysManager.h',
 ]
 
 EXPORTS.ipc += [
@@ -18,6 +20,8 @@ UNIFIED_SOURCES += [
     'AudioFocusManager.cpp',
     'MediaController.cpp',
     'MediaControlService.cpp',
+    'MediaHardwareKeysEvent.cpp',
+    'MediaHardwareKeysManager.cpp',
 ]
 
 include('/ipc/chromium/chromium-config.mozbuild')