gecko-dev/widget/gtk/MPRISServiceHandler.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * 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 WIDGET_GTK_MPRIS_SERVICE_HANDLER_H_
#define WIDGET_GTK_MPRIS_SERVICE_HANDLER_H_

#include <gio/gio.h>
#include "mozilla/dom/MediaControlKeysEvent.h"
#include "mozilla/Attributes.h"
#include "nsString.h"

#define DBUS_MRPIS_SERVICE_NAME "org.mpris.MediaPlayer2.firefox"
#define DBUS_MPRIS_OBJECT_PATH "/org/mpris/MediaPlayer2"

namespace mozilla {
namespace widget {

struct MPRISMetadata {
  const char* mKey;
  GVariant* mValue;
};

/**
 * This class implements the "MPRIS" D-Bus Service
 * (https://specifications.freedesktop.org/mpris-spec/2.2),
 * which is used to communicate with the Desktop Environment about the
 * Multimedia playing in Gecko.
 * Note that this interface requires many methods which may not be supported by
 * Gecko, the interface
 * however provides CanXYZ properties for these methods, so the method is
 * defined but won't be executed.
 *
 * Also note that the following defines are for parts that the MPRIS Spec
 * defines optional. The code won't
 * compile with any of the defines set, yet, as those aren't implemented yet and
 * probably never will be of
 * use for gecko. For sake of completeness, they have been added until the
 * decision about their implementation
 * is finally made.
 *
 * The constexpr'ed methods are capabilities of the user agent known at compile
 * time, e.g. we decided at
 * compile time whether we ever want to support closing the user agent via MPRIS
 * (Quit() and CanQuit()).
 *
 * Other properties like CanPlay() might depend on the runtime state (is there
 * media available for playback?)
 * and thus aren't a constexpr but merely a const method.
 */
class MPRISServiceHandler final : public dom::MediaControlKeysEventSource {
  NS_INLINE_DECL_REFCOUNTING(MPRISServiceHandler, override)
 public:
  // Note that this constructor does NOT initialize the MPRIS Service but only
  // this class. The method Open() is responsible for registering and MAY FAIL.
  MPRISServiceHandler() = default;
  bool Open() override;
  void Close() override;
  bool IsOpened() const override;

  // From the EventSource.
  void SetPlaybackState(dom::PlaybackState aState) override;

  // GetPlaybackState returns dom::PlaybackState. GetPlaybackStatus returns this
  // state converted into d-bus variants.
  GVariant* GetPlaybackStatus() const;

// Implementations of the MPRIS API Methods/Properties. constexpr'ed properties
// will be what the user agent doesn't support and thus they are known at
// compile time.
#ifdef MPRIS_FULLSCREEN
  bool GetFullscreen();
  void SetFullscreen(bool aFullscreen);
  bool CanSetFullscreen();
#endif
  bool HasTrackList();
  const char* Identity() const;
#ifdef MPRIS_DESKTOP_ENTRY
  const char* DesktopEntry();
#endif
  GVariant* SupportedUriSchemes();
  GVariant* SupportedMimeTypes();
  constexpr bool CanRaise();
  void Raise();
  constexpr bool CanQuit();
  void Quit();

  // :Player::Methods
  void Next();
  void Previous();
  void Pause();
  void PlayPause();
  void Stop();
  void Play();
  void Seek(int64_t aOffset);
  void SetPosition(char* aTrackId, int64_t aPosition);
  // bool is our custom addition: return false whether opening fails/is not
  // supported for that URI it will raise a DBUS Error
  bool OpenUri(char* aUri);

#ifdef MPRIS_LOOP_STATUS
  MPRISLoopStatus GetLoopStatus();
#endif

  double GetRate() const;
  bool SetRate(double aRate);
  constexpr double GetMinimumRate();
  constexpr double GetMaximumRate();

#ifdef MPRIS_SHUFFLE
  bool GetShuffle() const;
  void SetShuffle(bool aShuffle);
#endif

  std::vector<struct MPRISMetadata> GetDefaultMetadata();
  double GetVolume() const;
  bool SetVolume(double aVolume);
  int64_t GetPosition() const;

  bool CanGoNext() const;
  bool CanGoPrevious() const;
  bool CanPlay() const;
  bool CanPause() const;
  bool CanSeek() const;
  bool CanControl() const;

 private:
  ~MPRISServiceHandler();

  // Note: Registration Ids for the D-Bus start with 1, so a value of 0
  // indicates an error (or an object which wasn't initialized yet)

  // a handle to our bus registration/ownership
  guint mOwnerId = 0;
  // This is for the interface org.mpris.MediaPlayer2
  guint mRootRegistrationId = 0;
  // This is for the interface org.mpris.MediaPlayer2.Player
  guint mPlayerRegistrationId = 0;
  GDBusNodeInfo* mIntrospectionData = nullptr;
  GDBusConnection* mConnection = nullptr;
  bool mInitialized = false;
  nsAutoCString mIdentity;

  // Queries nsAppInfo to get the branded browser name and vendor
  void InitIdentity();

  // non-public API, called from events
  void OnNameAcquired(GDBusConnection* aConnection, const gchar* aName);
  void OnNameLost(GDBusConnection* aConnection, const gchar* aName);
  void OnBusAcquired(GDBusConnection* aConnection, const gchar* aName);

  static void OnNameAcquiredStatic(GDBusConnection* aConnection,
                                   const gchar* aName, gpointer aUserData);
  static void OnNameLostStatic(GDBusConnection* aConnection, const gchar* aName,
                               gpointer aUserData);
  static void OnBusAcquiredStatic(GDBusConnection* aConnection,
                                  const gchar* aName, gpointer aUserData);

  void EmitEvent(mozilla::dom::MediaControlKeysEvent event);
};

}  // namespace widget
}  // namespace mozilla

#endif  // WIDGET_GTK_MPRIS_SERVICE_HANDLER_H_