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products/sources/formale Sprachen/C/Firefox/dom/html/ (Browser von der Mozilla Stiftung Version 136.0.1^©) Datei vom 10.2.2025 mit Größe 6 kB

Quelle TextTrackManager.h Sprache: C

/* -*- 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 http://mozilla.org/MPL/2.0/. */

#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 {
private:
 HTMLMediaElement* mMediaElement;
 Maybe<uint32_t> TrackChildPosition(TextTrack* aTrack) const;

public:
 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 {
 ~TextTrackManager();

public:
 NS_DECL_CYCLE_COLLECTING_ISUPPORTS
 NS_DECL_CYCLE_COLLECTION_CLASS(TextTrackManager)

 NS_DECL_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 , , , <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. , , , <ruby>, and <rt> all become
 * HTMLElements of their corresponding HTML markup tags. <c> and <v> are
 * converted to 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
 * http://dev.w3.org/html5/webvtt/#webvtt-cue-text-dom-construction-rules.
 * 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();

private:
 /**
 * 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 {
 NS_DECL_ISUPPORTS

 public:
 explicit ShutdownObserverProxy(TextTrackManager* aManager)
 : mManager(aManager) {
 nsContentUtils::RegisterShutdownObserver(this);
 }

 NS_IMETHODIMP Observe(nsISupports* aSubject, const char* aTopic,
 const char16_t* aData) override {
 MOZ_ASSERT(NS_IsMainThread());
 if (strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
 if (mManager) {
 mManager->NotifyShutdown();
 }
 Unregister();
 }
 return NS_OK;
 }

 void Unregister();

 private:
 ~ShutdownObserverProxy() = default;

 TextTrackManager* mManager;
 };

 RefPtr<ShutdownObserverProxy> mShutdownProxy;
 bool mShutdown;
};

} // namespace dom
} // namespace mozilla

#endif // mozilla_dom_TextTrackManager_h

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