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 {
  13 namespace dom {
  14
  15 class MediaTrackList;
  16 class VideoTrack;
  17 class AudioTrack;
  18
  19 /**
  20  * Base class of AudioTrack and VideoTrack. The AudioTrack and VideoTrack
  21  * objects represent specific tracks of a media resource. Each track has aspects
  22  * of an identifier, category, label, and language, even if a track is removed
  23  * from its corresponding track list, those aspects do not change.
  24  *
  25  * When fetching the media resource, an audio/video track is created if the
  26  * media resource is found to have an audio/video track. When the UA has learned
  27  * that an audio/video track has ended, this audio/video track will be removed
  28  * from its corresponding track list.
  29  *
  30  * Although AudioTrack and VideoTrack are not EventTargets, TextTrack is, and
  31  * TextTrack inherits from MediaTrack as well (or is going to).
  32  */
  33 class MediaTrack : public DOMEventTargetHelper
  34 {
  35 public:
  36   MediaTrack(nsIGlobalObject* aOwnerGlobal,
  37              const nsAString& aId,
  38              const nsAString& aKind,
  39              const nsAString& aLabel,
  40              const nsAString& aLanguage);
  41
  42   NS_DECL_ISUPPORTS_INHERITED
  43   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(MediaTrack, DOMEventTargetHelper)
  44
  45   enum {
  46     DEFAULT = 0,
  47     FIRE_NO_EVENTS = 1 << 0,
  48   };
  49   // The default behavior of enabling an audio track or selecting a video track
  50   // fires a change event and notifies its media resource about the changes.
  51   // It should not fire any events when fetching media resource.
  52   virtual void SetEnabledInternal(bool aEnabled, int aFlags) = 0;
  53
  54   virtual AudioTrack* AsAudioTrack()
  55   {
  56     return nullptr;
  57   }
  58
  59   virtual VideoTrack* AsVideoTrack()
  60   {
  61     return nullptr;
  62   }
  63
  64   const nsString& GetId() const
  65   {
  66     return mId;
  67   }
  68
  69   // WebIDL
  70   void GetId(nsAString& aId) const
  71   {
  72     aId = mId;
  73   }
  74   void GetKind(nsAString& aKind) const
  75   {
  76     aKind = mKind;
  77   }
  78   void GetLabel(nsAString& aLabel) const
  79   {
  80     aLabel = mLabel;
  81   }
  82   void GetLanguage(nsAString& aLanguage) const
  83   {
  84     aLanguage = mLanguage;
  85   }
  86
  87   friend class MediaTrackList;
  88
  89 protected:
  90   virtual ~MediaTrack();
  91
  92   void SetTrackList(MediaTrackList* aList);
  93
  94   RefPtr<MediaTrackList> mList;
  95   nsString mId;
  96   nsString mKind;
  97   nsString mLabel;
  98   nsString mLanguage;
  99 };
 100
 101 } // namespace dom
 102 } // namespace mozilla
 103
 104 #endif // mozilla_dom_MediaTrack_h