dom/html/TextTrackManager.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   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 file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_TextTrackManager_h
   8 #define mozilla_dom_TextTrackManager_h
   9
  10 #include "mozilla/dom/TextTrack.h"
  11 #include "mozilla/dom/TextTrackList.h"
  12 #include "mozilla/dom/TextTrackCueList.h"
  13 #include "mozilla/StaticPtr.h"
  14 #include "nsContentUtils.h"
  15 #include "nsIDOMEventListener.h"
  16 #include "TimeUnits.h"
  17
  18 class nsIWebVTTParserWrapper;
  19
  20 namespace mozilla {
  21 template <typename T>
  22 class Maybe;
  23 namespace dom {
  24
  25 class HTMLMediaElement;
  26
  27 class CompareTextTracks {
  28  private:
  29   HTMLMediaElement* mMediaElement;
  30   Maybe<uint32_t> TrackChildPosition(TextTrack* aTrack) const;
  31
  32  public:
  33   explicit CompareTextTracks(HTMLMediaElement* aMediaElement);
  34   bool Equals(TextTrack* aOne, TextTrack* aTwo) const;
  35   bool LessThan(TextTrack* aOne, TextTrack* aTwo) const;
  36 };
  37
  38 class TextTrack;
  39 class TextTrackCue;
  40
  41 class TextTrackManager final : public nsIDOMEventListener {
  42   ~TextTrackManager();
  43
  44  public:
  45   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  46   NS_DECL_CYCLE_COLLECTION_CLASS(TextTrackManager)
  47
  48   NS_DECL_NSIDOMEVENTLISTENER
  49
  50   explicit TextTrackManager(HTMLMediaElement* aMediaElement);
  51
  52   TextTrackList* GetTextTracks() const;
  53   already_AddRefed<TextTrack> AddTextTrack(TextTrackKind aKind,
  54                                            const nsAString& aLabel,
  55                                            const nsAString& aLanguage,
  56                                            TextTrackMode aMode,
  57                                            TextTrackReadyState aReadyState,
  58                                            TextTrackSource aTextTrackSource);
  59   void AddTextTrack(TextTrack* aTextTrack);
  60   void RemoveTextTrack(TextTrack* aTextTrack, bool aPendingListOnly);
  61   void DidSeek();
  62
  63   void NotifyCueAdded(TextTrackCue& aCue);
  64   void AddCues(TextTrack* aTextTrack);
  65   void NotifyCueRemoved(TextTrackCue& aCue);
  66   /**
  67    * Overview of WebVTT cuetext and anonymous content setup.
  68    *
  69    * WebVTT nodes are the parsed version of WebVTT cuetext. WebVTT cuetext is
  70    * the portion of a WebVTT cue that specifies what the caption will actually
  71    * show up as on screen.
  72    *
  73    * WebVTT cuetext can contain markup that loosely relates to HTML markup. It
  74    * can contain tags like <b>, <u>, <i>, <c>, <v>, <ruby>, <rt>, <lang>,
  75    * including timestamp tags.
  76    *
  77    * When the caption is ready to be displayed the WebVTT nodes are converted
  78    * over to anonymous DOM content. <i>, <u>, <b>, <ruby>, and <rt> all become
  79    * HTMLElements of their corresponding HTML markup tags. <c> and <v> are
  80    * converted to <span> tags. Timestamp tags are converted to XML processing
  81    * instructions. Additionally, all cuetext tags support specifying of classes.
  82    * This takes the form of <foo.class.subclass>. These classes are then parsed
  83    * and set as the anonymous content's class attribute.
  84    *
  85    * Rules on constructing DOM objects from WebVTT nodes can be found here
  86    * http://dev.w3.org/html5/webvtt/#webvtt-cue-text-dom-construction-rules.
  87    * Current rules are taken from revision on April 15, 2013.
  88    */
  89
  90   void PopulatePendingList();
  91
  92   void AddListeners();
  93
  94   // The HTMLMediaElement that this TextTrackManager manages the TextTracks of.
  95   RefPtr<HTMLMediaElement> mMediaElement;
  96
  97   void DispatchTimeMarchesOn();
  98   void TimeMarchesOn();
  99   void DispatchUpdateCueDisplay();
 100
 101   void NotifyShutdown() { mShutdown = true; }
 102
 103   void NotifyCueUpdated(TextTrackCue* aCue);
 104
 105   void NotifyReset();
 106
 107   bool IsLoaded();
 108
 109  private:
 110   /**
 111    * Converts the TextTrackCue's cuetext into a tree of DOM objects
 112    * and attaches it to a div on its owning TrackElement's
 113    * MediaElement's caption overlay.
 114    */
 115   void UpdateCueDisplay();
 116
 117   // List of the TextTrackManager's owning HTMLMediaElement's TextTracks.
 118   RefPtr<TextTrackList> mTextTracks;
 119   // List of text track objects awaiting loading.
 120   RefPtr<TextTrackList> mPendingTextTracks;
 121   // List of newly introduced Text Track cues.
 122
 123   // Contain all cues for a MediaElement. Not sorted.
 124   RefPtr<TextTrackCueList> mNewCues;
 125
 126   // True if the media player playback changed due to seeking prior to and
 127   // during running the "Time Marches On" algorithm.
 128   bool mHasSeeked;
 129   // Playback position at the time of last "Time Marches On" call
 130   media::TimeUnit mLastTimeMarchesOnCalled;
 131
 132   bool mTimeMarchesOnDispatched;
 133   bool mUpdateCueDisplayDispatched;
 134
 135   static StaticRefPtr<nsIWebVTTParserWrapper> sParserWrapper;
 136
 137   bool performedTrackSelection;
 138
 139   // Runs the algorithm for performing automatic track selection.
 140   void HonorUserPreferencesForTrackSelection();
 141   // Performs track selection for a single TextTrackKind.
 142   void PerformTrackSelection(TextTrackKind aTextTrackKind);
 143   // Performs track selection for a set of TextTrackKinds, for example,
 144   // 'subtitles' and 'captions' should be selected together.
 145   void PerformTrackSelection(TextTrackKind aTextTrackKinds[], uint32_t size);
 146   void GetTextTracksOfKinds(TextTrackKind aTextTrackKinds[], uint32_t size,
 147                             nsTArray<TextTrack*>& aTextTracks);
 148   void GetTextTracksOfKind(TextTrackKind aTextTrackKind,
 149                            nsTArray<TextTrack*>& aTextTracks);
 150   bool TrackIsDefault(TextTrack* aTextTrack);
 151
 152   bool IsShutdown() const;
 153
 154   // This function will check media element's show poster flag to decide whether
 155   // we need to run `TimeMarchesOn`.
 156   void MaybeRunTimeMarchesOn();
 157
 158   class ShutdownObserverProxy final : public nsIObserver {
 159     NS_DECL_ISUPPORTS
 160
 161    public:
 162     explicit ShutdownObserverProxy(TextTrackManager* aManager)
 163         : mManager(aManager) {
 164       nsContentUtils::RegisterShutdownObserver(this);
 165     }
 166
 167     NS_IMETHODIMP Observe(nsISupports* aSubject, const char* aTopic,
 168                           const char16_t* aData) override {
 169       MOZ_ASSERT(NS_IsMainThread());
 170       if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
 171         if (mManager) {
 172           mManager->NotifyShutdown();
 173         }
 174         Unregister();
 175       }
 176       return NS_OK;
 177     }
 178
 179     void Unregister();
 180
 181    private:
 182     ~ShutdownObserverProxy() = default;
 183
 184     TextTrackManager* mManager;
 185   };
 186
 187   RefPtr<ShutdownObserverProxy> mShutdownProxy;
 188   bool mShutdown;
 189 };
 190
 191 }  // namespace dom
 192 }  // namespace mozilla
 193
 194 #endif  // mozilla_dom_TextTrackManager_h