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/* -*- 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 */
#ifndef mozilla_dom_TextTrackManager_h
#define mozilla_dom_TextTrackManager_h
#include "mozilla/dom/TextTrack.h"
#include "mozilla/dom/TextTrackList.h"
#include "mozilla/dom/TextTrackCueList.h"
#include "mozilla/StaticPtr.h"
#include "nsContentUtils.h"
#include "nsIDOMEventListener.h"
#include "TimeUnits.h"
class nsIWebVTTParserWrapper;
namespace mozilla {
template <typename T>
class Maybe;
namespace dom {
class HTMLMediaElement;
class CompareTextTracks {
HTMLMediaElement* mMediaElement;
Maybe<uint32_t> TrackChildPosition(TextTrack* aTrack) const;
explicit CompareTextTracks(HTMLMediaElement* aMediaElement);
bool Equals(TextTrack* aOne, TextTrack* aTwo) const;
bool LessThan(TextTrack* aOne, TextTrack* aTwo) const;
class TextTrack;
class TextTrackCue;
class TextTrackManager final : public nsIDOMEventListener {
explicit TextTrackManager(HTMLMediaElement* aMediaElement);
TextTrackList* GetTextTracks() const;
already_AddRefed<TextTrack> AddTextTrack(TextTrackKind aKind,
const nsAString& aLabel,
const nsAString& aLanguage,
TextTrackMode aMode,
TextTrackReadyState aReadyState,
TextTrackSource aTextTrackSource);
void AddTextTrack(TextTrack* aTextTrack);
void RemoveTextTrack(TextTrack* aTextTrack, bool aPendingListOnly);
void DidSeek();
void NotifyCueAdded(TextTrackCue& aCue);
void AddCues(TextTrack* aTextTrack);
void NotifyCueRemoved(TextTrackCue& aCue);
* Overview of WebVTT cuetext and anonymous content setup.
* WebVTT nodes are the parsed version of WebVTT cuetext. WebVTT cuetext is
* the portion of a WebVTT cue that specifies what the caption will actually
* show up as on screen.
* WebVTT cuetext can contain markup that loosely relates to HTML markup. It
* can contain tags like <b>, <u>, <i>, <c>, <v>, <ruby>, <rt>, <lang>,
* including timestamp tags.
* When the caption is ready to be displayed the WebVTT nodes are converted
* over to anonymous DOM content. <i>, <u>, <b>, <ruby>, and <rt> all become
* HTMLElements of their corresponding HTML markup tags. <c> and <v> are
* converted to <span> tags. Timestamp tags are converted to XML processing
* instructions. Additionally, all cuetext tags support specifying of classes.
* This takes the form of <foo.class.subclass>. These classes are then parsed
* and set as the anonymous content's class attribute.
* Rules on constructing DOM objects from WebVTT nodes can be found here
* Current rules are taken from revision on April 15, 2013.
void PopulatePendingList();
void AddListeners();
// The HTMLMediaElement that this TextTrackManager manages the TextTracks of.
RefPtr<HTMLMediaElement> mMediaElement;
void DispatchTimeMarchesOn();
void TimeMarchesOn();
void DispatchUpdateCueDisplay();
void NotifyShutdown() { mShutdown = true; }
void NotifyCueUpdated(TextTrackCue* aCue);
void NotifyReset();
bool IsLoaded();
* Converts the TextTrackCue's cuetext into a tree of DOM objects
* and attaches it to a div on its owning TrackElement's
* MediaElement's caption overlay.
void UpdateCueDisplay();
// List of the TextTrackManager's owning HTMLMediaElement's TextTracks.
RefPtr<TextTrackList> mTextTracks;
// List of text track objects awaiting loading.
RefPtr<TextTrackList> mPendingTextTracks;
// List of newly introduced Text Track cues.
// Contain all cues for a MediaElement. Not sorted.
RefPtr<TextTrackCueList> mNewCues;
// True if the media player playback changed due to seeking prior to and
// during running the "Time Marches On" algorithm.
bool mHasSeeked;
// Playback position at the time of last "Time Marches On" call
media::TimeUnit mLastTimeMarchesOnCalled;
bool mTimeMarchesOnDispatched;
bool mUpdateCueDisplayDispatched;
static StaticRefPtr<nsIWebVTTParserWrapper> sParserWrapper;
bool performedTrackSelection;
// Runs the algorithm for performing automatic track selection.
void HonorUserPreferencesForTrackSelection();
// Performs track selection for a single TextTrackKind.
void PerformTrackSelection(TextTrackKind aTextTrackKind);
// Performs track selection for a set of TextTrackKinds, for example,
// 'subtitles' and 'captions' should be selected together.
void PerformTrackSelection(TextTrackKind aTextTrackKinds[], uint32_t size);
void GetTextTracksOfKinds(TextTrackKind aTextTrackKinds[], uint32_t size,
nsTArray<TextTrack*>& aTextTracks);
void GetTextTracksOfKind(TextTrackKind aTextTrackKind,
nsTArray<TextTrack*>& aTextTracks);
bool TrackIsDefault(TextTrack* aTextTrack);
bool IsShutdown() const;
// This function will check media element's show poster flag to decide whether
// we need to run `TimeMarchesOn`.
void MaybeRunTimeMarchesOn();
class ShutdownObserverProxy final : public nsIObserver {
explicit ShutdownObserverProxy(TextTrackManager* aManager)
: mManager(aManager) {
NS_IMETHODIMP Observe(nsISupports* aSubject, const char* aTopic,
const char16_t* aData) override {
if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
if (mManager) {
return NS_OK;
void Unregister();
~ShutdownObserverProxy() = default;
TextTrackManager* mManager;
RefPtr<ShutdownObserverProxy> mShutdownProxy;
bool mShutdown;
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_TextTrackManager_h