dom/media/MediaTrack.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 et tw=78: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_MediaTrack_h
   8 #define mozilla_dom_MediaTrack_h
   9
  10 #include "mozilla/DOMEventTargetHelper.h"
  11
  12 namespace mozilla::dom {
  13
  14 class MediaTrackList;
  15 class VideoTrack;
  16 class AudioTrack;
  17
  18 /**
  19  * Base class of AudioTrack and VideoTrack. The AudioTrack and VideoTrack
  20  * objects represent specific tracks of a media resource. Each track has aspects
  21  * of an identifier, category, label, and language, even if a track is removed
  22  * from its corresponding track list, those aspects do not change.
  23  *
  24  * When fetching the media resource, an audio/video track is created if the
  25  * media resource is found to have an audio/video track. When the UA has learned
  26  * that an audio/video track has ended, this audio/video track will be removed
  27  * from its corresponding track list.
  28  *
  29  * Although AudioTrack and VideoTrack are not EventTargets, TextTrack is, and
  30  * TextTrack inherits from MediaTrack as well (or is going to).
  31  */
  32 class MediaTrack : public DOMEventTargetHelper {
  33  public:
  34   MediaTrack(nsIGlobalObject* aOwnerGlobal, const nsAString& aId,
  35              const nsAString& aKind, const nsAString& aLabel,
  36              const nsAString& aLanguage);
  37
  38   NS_DECL_ISUPPORTS_INHERITED
  39   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(dom::MediaTrack,
  40                                            DOMEventTargetHelper)
  41
  42   enum {
  43     DEFAULT = 0,
  44     FIRE_NO_EVENTS = 1 << 0,
  45   };
  46   // The default behavior of enabling an audio track or selecting a video track
  47   // fires a change event and notifies its media resource about the changes.
  48   // It should not fire any events when fetching media resource.
  49   virtual void SetEnabledInternal(bool aEnabled, int aFlags) = 0;
  50
  51   virtual AudioTrack* AsAudioTrack() { return nullptr; }
  52
  53   virtual VideoTrack* AsVideoTrack() { return nullptr; }
  54
  55   const nsString& GetId() const { return mId; }
  56
  57   // WebIDL
  58   void GetId(nsAString& aId) const { aId = mId; }
  59   void GetKind(nsAString& aKind) const { aKind = mKind; }
  60   void GetLabel(nsAString& aLabel) const { aLabel = mLabel; }
  61   void GetLanguage(nsAString& aLanguage) const { aLanguage = mLanguage; }
  62
  63   friend class MediaTrackList;
  64
  65  protected:
  66   virtual ~MediaTrack();
  67
  68   void SetTrackList(MediaTrackList* aList);
  69
  70   RefPtr<MediaTrackList> mList;
  71   nsString mId;
  72   nsString mKind;
  73   nsString mLabel;
  74   nsString mLanguage;
  75 };
  76
  77 }  // namespace mozilla::dom
  78
  79 #endif  // mozilla_dom_MediaTrack_h