C++ TextTrackCue::removeDisplayTree方法代码示例

//.........这里部分代码省略.........
    // Note: An explicit task is added only if the cue is NOT a zero or
    // negative length cue. Otherwise, the need for an exit event is
    // checked when these tasks are actually queued below. This doesn't
    // affect sorting events before dispatch either, because the exit
    // event has the same time as the enter event.
    if (missedCue.data()->startTime() < missedCue.data()->endTime()) {
      eventTasks.append(
          std::make_pair(missedCue.data()->endTime(), missedCue.data()));
    }
  }

  for (const auto& previousCue : previousCues) {
    // 10 - For each text track cue in other cues that has its text
    // track cue active flag set prepare an event named exit for the
    // TextTrackCue object with the text track cue end time.
    if (!currentCues.contains(previousCue)) {
      eventTasks.append(
          std::make_pair(previousCue.data()->endTime(), previousCue.data()));
    }
  }

  for (const auto& currentCue : currentCues) {
    // 11 - For each text track cue in current cues that does not have its
    // text track cue active flag set, prepare an event named enter for the
    // TextTrackCue object with the text track cue start time.
    if (!previousCues.contains(currentCue)) {
      eventTasks.append(
          std::make_pair(currentCue.data()->startTime(), currentCue.data()));
    }
  }

  // 12 - Sort the tasks in events in ascending time order (tasks with earlier
  // times first).
  nonCopyingSort(eventTasks.begin(), eventTasks.end(), eventTimeCueCompare);

  for (const auto& task : eventTasks) {
    if (!affectedTracks.contains(task.second->track()))
      affectedTracks.append(task.second->track());

    // 13 - Queue each task in events, in list order.

    // Each event in eventTasks may be either an enterEvent or an exitEvent,
    // depending on the time that is associated with the event. This
    // correctly identifies the type of the event, if the startTime is
    // less than the endTime in the cue.
    if (task.second->startTime() >= task.second->endTime()) {
      mediaElement.scheduleEvent(
          createEventWithTarget(EventTypeNames::enter, task.second.get()));
      mediaElement.scheduleEvent(
          createEventWithTarget(EventTypeNames::exit, task.second.get()));
    } else {
      bool isEnterEvent = task.first == task.second->startTime();
      AtomicString eventName =
          isEnterEvent ? EventTypeNames::enter : EventTypeNames::exit;
      mediaElement.scheduleEvent(
          createEventWithTarget(eventName, task.second.get()));
    }
  }

  // 14 - Sort affected tracks in the same order as the text tracks appear in
  // the media element's list of text tracks, and remove duplicates.
  nonCopyingSort(affectedTracks.begin(), affectedTracks.end(),
                 trackIndexCompare);

  // 15 - For each text track in affected tracks, in the list order, queue a
  // task to fire a simple event named cuechange at the TextTrack object, and,
  // ...
  for (const auto& track : affectedTracks) {
    mediaElement.scheduleEvent(
        createEventWithTarget(EventTypeNames::cuechange, track.get()));

    // ... if the text track has a corresponding track element, to then fire a
    // simple event named cuechange at the track element as well.
    if (track->trackType() == TextTrack::TrackElement) {
      HTMLTrackElement* trackElement =
          static_cast<LoadableTextTrack*>(track.get())->trackElement();
      DCHECK(trackElement);
      mediaElement.scheduleEvent(
          createEventWithTarget(EventTypeNames::cuechange, trackElement));
    }
  }

  // 16 - Set the text track cue active flag of all the cues in the current
  // cues, and unset the text track cue active flag of all the cues in the
  // other cues.
  for (const auto& cue : currentCues)
    cue.data()->setIsActive(true);

  for (const auto& previousCue : previousCues) {
    if (!currentCues.contains(previousCue)) {
      TextTrackCue* cue = previousCue.data();
      cue->setIsActive(false);
      cue->removeDisplayTree();
    }
  }

  // Update the current active cues.
  m_currentlyActiveCues = currentCues;
  mediaElement.updateTextTrackDisplay();
}