Move text track active list management to CueTimeline

Source/core/html/track/CueTimeline.cpp

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/html/track/CueTimeline.h"
+
+#include "core/events/Event.h"
+#include "core/html/HTMLMediaElement.h"
+#include "core/html/HTMLTrackElement.h"
+#include "core/html/track/LoadableTextTrack.h"
+#include "core/html/track/TextTrack.h"
+#include "core/html/track/TextTrackCue.h"
+#include "core/html/track/TextTrackCueList.h"
+#include "wtf/NonCopyingSort.h"
+
+namespace blink {
+
+CueTimeline::CueTimeline(HTMLMediaElement& mediaElement)
+    : m_mediaElement(&mediaElement)
+    , m_lastUpdateTime(-1)
+    , m_ignoreUpdate(0)
+{
+}
+
+void CueTimeline::addCues(TextTrack* track, const TextTrackCueList* cues)
+{
+    ASSERT(track->mode() != TextTrack::disabledKeyword());
+
+    TrackDisplayUpdateScope scope(*this);
+    for (size_t i = 0; i < cues->length(); ++i)
+        addCue(cues->item(i)->track(), cues->item(i));
+}
+
+void CueTimeline::addCue(TextTrack* track, PassRefPtrWillBeRawPtr<TextTrackCue> cue)
+{
+    ASSERT(track->mode() != TextTrack::disabledKeyword());
+
+    // Negative duration cues need be treated in the interval tree as
+    // zero-length cues.
+    double endTime = std::max(cue->startTime(), cue->endTime());
+
+    CueInterval interval = m_cueTree.createInterval(cue->startTime(), endTime, cue.get());
+    if (!m_cueTree.contains(interval))
+        m_cueTree.add(interval);
+    updateActiveCues(mediaElement().currentTime());
+}
+
+void CueTimeline::removeCues(TextTrack*, const TextTrackCueList* cues)
+{
+    TrackDisplayUpdateScope scope(*this);
+    for (size_t i = 0; i < cues->length(); ++i)
+        removeCue(cues->item(i)->track(), cues->item(i));
+}
+
+void CueTimeline::removeCue(TextTrack*, PassRefPtrWillBeRawPtr<TextTrackCue> cue)
+{
+    // Negative duration cues need to be treated in the interval tree as
+    // zero-length cues.
+    double endTime = std::max(cue->startTime(), cue->endTime());
+
+    CueInterval interval = m_cueTree.createInterval(cue->startTime(), endTime, cue.get());
+    m_cueTree.remove(interval);
+
+    // Since the cue will be removed from the media element and likely the
+    // TextTrack might also be destructed, notifying the region of the cue
+    // removal shouldn't be done.
+    cue->notifyRegionWhenRemovingDisplayTree(false);
+
+    size_t index = m_currentlyActiveCues.find(interval);
+    if (index != kNotFound) {
+        m_currentlyActiveCues.remove(index);
+        cue->setIsActive(false);
+    }
+    cue->removeDisplayTree();
+    updateActiveCues(mediaElement().currentTime());
+
+    cue->notifyRegionWhenRemovingDisplayTree(true);
+}
+
+static bool trackIndexCompare(TextTrack* a, TextTrack* b)
+{
+    return a->trackIndex() - b->trackIndex() < 0;
+}
+
+static bool eventTimeCueCompare(const std::pair<double, TextTrackCue*>& a, const std::pair<double, TextTrackCue*>& b)
+{
+    // 12 - Sort the tasks in events in ascending time order (tasks with earlier
+    // times first).
+    if (a.first != b.first)
+        return a.first - b.first < 0;
+
+    // If the cues belong to different text tracks, it doesn't make sense to
+    // compare the two tracks by the relative cue order, so return the relative
+    // track order.
+    if (a.second->track() != b.second->track())
+        return trackIndexCompare(a.second->track(), b.second->track());
+
+    // 12 - Further sort tasks in events that have the same time by the
+    // relative text track cue order of the text track cues associated
+    // with these tasks.
+    return a.second->cueIndex() - b.second->cueIndex() < 0;
+}
+
+void CueTimeline::updateActiveCues(double movieTime)
+{
+    // 4.8.10.8 Playing the media resource
+
+    //  If the current playback position changes while the steps are running,
+    //  then the user agent must wait for the steps to complete, and then must
+    //  immediately rerun the steps.
+    if (ignoreUpdateRequests())
+        return;
+
+    HTMLMediaElement& mediaElement = this->mediaElement();
+
+    // 1 - Let current cues be a list of cues, initialized to contain all the
+    // cues of all the hidden, showing, or showing by default text tracks of the
+    // media element (not the disabled ones) whose start times are less than or
+    // equal to the current playback position and whose end times are greater
+    // than the current playback position.
+    CueList currentCues;
+
+    // The user agent must synchronously unset [the text track cue active] flag
+    // whenever ... the media element's readyState is changed back to HAVE_NOTHING.
+    if (mediaElement.readyState() != HTMLMediaElement::HAVE_NOTHING && mediaElement.webMediaPlayer())
+        currentCues = m_cueTree.allOverlaps(m_cueTree.createInterval(movieTime, movieTime));
+
+    CueList previousCues;
+    CueList missedCues;
+
+    // 2 - Let other cues be a list of cues, initialized to contain all the cues
+    // of hidden, showing, and showing by default text tracks of the media
+    // element that are not present in current cues.
+    previousCues = m_currentlyActiveCues;
+
+    // 3 - Let last time be the current playback position at the time this
+    // algorithm was last run for this media element, if this is not the first
+    // time it has run.
+    double lastTime = m_lastUpdateTime;
+    double lastSeekTime = mediaElement.lastSeekTime();
+
+    // 4 - If the current playback position has, since the last time this
+    // algorithm was run, only changed through its usual monotonic increase
+    // during normal playback, then let missed cues be the list of cues in other
+    // cues whose start times are greater than or equal to last time and whose
+    // end times are less than or equal to the current playback position.
+    // Otherwise, let missed cues be an empty list.
+    if (lastTime >= 0 && lastSeekTime < movieTime) {
+        CueList potentiallySkippedCues =
+            m_cueTree.allOverlaps(m_cueTree.createInterval(lastTime, movieTime));
+
+        for (CueInterval cue : potentiallySkippedCues) {
+            // Consider cues that may have been missed since the last seek time.
+            if (cue.low() > std::max(lastSeekTime, lastTime) && cue.high() < movieTime)
+                missedCues.append(cue);
+        }
+    }
+
+    m_lastUpdateTime = movieTime;
+
+    // 5 - If the time was reached through the usual monotonic increase of the
+    // current playback position during normal playback, and if the user agent
+    // has not fired a timeupdate event at the element in the past 15 to 250ms
+    // and is not still running event handlers for such an event, then the user
+    // agent must queue a task to fire a simple event named timeupdate at the
+    // element. (In the other cases, such as explicit seeks, relevant events get
+    // fired as part of the overall process of changing the current playback
+    // position.)
+    if (!mediaElement.seeking() && lastSeekTime < lastTime)
+        mediaElement.scheduleTimeupdateEvent(true);
+
+    // Explicitly cache vector sizes, as their content is constant from here.
+    size_t currentCuesSize = currentCues.size();
+    size_t missedCuesSize = missedCues.size();
+    size_t previousCuesSize = previousCues.size();
+
+    // 6 - If all of the cues in current cues have their text track cue active
+    // flag set, none of the cues in other cues have their text track cue active
+    // flag set, and missed cues is empty, then abort these steps.
+    bool activeSetChanged = missedCuesSize;
+
+    for (size_t i = 0; !activeSetChanged && i < previousCuesSize; ++i) {
+        if (!currentCues.contains(previousCues[i]) && previousCues[i].data()->isActive())
+            activeSetChanged = true;
+    }
+
+    for (CueInterval currentCue : currentCues) {
+        currentCue.data()->updateDisplayTree(movieTime);
+
+        if (!currentCue.data()->isActive())
+            activeSetChanged = true;
+    }
+
+    if (!activeSetChanged)
+        return;
+
+    // 7 - If the time was reached through the usual monotonic increase of the
+    // current playback position during normal playback, and there are cues in
+    // other cues that have their text track cue pause-on-exi flag set and that
+    // either have their text track cue active flag set or are also in missed
+    // cues, then immediately pause the media element.
+    for (size_t i = 0; !mediaElement.paused() && i < previousCuesSize; ++i) {
+        if (previousCues[i].data()->pauseOnExit()
+            && previousCues[i].data()->isActive()
+            && !currentCues.contains(previousCues[i]))
+            mediaElement.pause();
+    }
+
+    for (size_t i = 0; !mediaElement.paused() && i < missedCuesSize; ++i) {
+        if (missedCues[i].data()->pauseOnExit())
+            mediaElement.pause();
+    }
+
+    // 8 - Let events be a list of tasks, initially empty. Each task in this
+    // list will be associated with a text track, a text track cue, and a time,
+    // which are used to sort the list before the tasks are queued.
+    WillBeHeapVector<std::pair<double, RawPtrWillBeMember<TextTrackCue>>> eventTasks;
+
+    // 8 - Let affected tracks be a list of text tracks, initially empty.
+    WillBeHeapVector<RawPtrWillBeMember<TextTrack>> affectedTracks;
+
+    for (size_t i = 0; i < missedCuesSize; ++i) {
+        // 9 - For each text track cue in missed cues, prepare an event named enter
+        // for the TextTrackCue object with the text track cue start time.
+        eventTasks.append(std::make_pair(missedCues[i].data()->startTime(), missedCues[i].data()));
+
+        // 10 - For each text track [...] in missed cues, prepare an event
+        // named exit for the TextTrackCue object with the  with the later of
+        // the text track cue end time and the text track cue start time.
+
+        // 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 (missedCues[i].data()->startTime() < missedCues[i].data()->endTime())
+            eventTasks.append(std::make_pair(missedCues[i].data()->endTime(), missedCues[i].data()));
+    }
+
+    for (size_t i = 0; i < previousCuesSize; ++i) {
+        // 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(previousCues[i]))
+            eventTasks.append(std::make_pair(previousCues[i].data()->endTime(), previousCues[i].data()));
+    }
+
+    for (size_t i = 0; i < currentCuesSize; ++i) {
+        // 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(currentCues[i]))
+            eventTasks.append(std::make_pair(currentCues[i].data()->startTime(), currentCues[i].data()));
+    }
+
+    // 12 - Sort the tasks in events in ascending time order (tasks with earlier
+    // times first).
+    nonCopyingSort(eventTasks.begin(), eventTasks.end(), eventTimeCueCompare);
+
+    for (size_t i = 0; i < eventTasks.size(); ++i) {
+        if (!affectedTracks.contains(eventTasks[i].second->track()))
+            affectedTracks.append(eventTasks[i].second->track());
+
+        // 13 - Queue each task in events, in list order.
+        RefPtrWillBeRawPtr<Event> event = nullptr;
+
+        // 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 (eventTasks[i].second->startTime() >= eventTasks[i].second->endTime()) {
+            event = Event::create(EventTypeNames::enter);
+            event->setTarget(eventTasks[i].second);
+            mediaElement.scheduleEvent(event.release());
+
+            event = Event::create(EventTypeNames::exit);
+            event->setTarget(eventTasks[i].second);
+            mediaElement.scheduleEvent(event.release());
+        } else {
+            if (eventTasks[i].first == eventTasks[i].second->startTime())
+                event = Event::create(EventTypeNames::enter);
+            else
+                event = Event::create(EventTypeNames::exit);
+
+            event->setTarget(eventTasks[i].second);
+            mediaElement.scheduleEvent(event.release());
+        }
+    }
+
+    // 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 (size_t i = 0; i < affectedTracks.size(); ++i) {
+        RefPtrWillBeRawPtr<Event> event = Event::create(EventTypeNames::cuechange);
+        event->setTarget(affectedTracks[i]);
+
+        mediaElement.scheduleEvent(event.release());
+
+        // ... if the text track has a corresponding track element, to then fire a
+        // simple event named cuechange at the track element as well.
+        if (affectedTracks[i]->trackType() == TextTrack::TrackElement) {
+            RefPtrWillBeRawPtr<Event> event = Event::create(EventTypeNames::cuechange);

[brucedawson, 2015/02/18 21:06:40]

The declaration of 'event' shadows the declaration with the same name/type on
line 298 (eight lines earlier). There is no indication that this is a bug, but
it is potentially confusing. Consider renaming one of the variables?

This showed up as a new warning on the /analyze builder:

http://build.chromium.org/p/chromium.fyi/builders/Chromium%20Windows%20Analyze

+            HTMLTrackElement* trackElement = static_cast<LoadableTextTrack*>(affectedTracks[i].get())->trackElement();
+            ASSERT(trackElement);
+            event->setTarget(trackElement);
+
+            mediaElement.scheduleEvent(event.release());
+        }
+    }
+
+    // 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 (size_t i = 0; i < currentCuesSize; ++i)
+        currentCues[i].data()->setIsActive(true);
+
+    for (size_t i = 0; i < previousCuesSize; ++i) {
+        if (!currentCues.contains(previousCues[i]))
+            previousCues[i].data()->setIsActive(false);
+    }
+
+    // Update the current active cues.
+    m_currentlyActiveCues = currentCues;
+
+    if (activeSetChanged)
+        mediaElement.updateTextTrackDisplay();
+}
+
+void CueTimeline::beginIgnoringUpdateRequests()
+{
+    ++m_ignoreUpdate;
+}
+
+void CueTimeline::endIgnoringUpdateRequests()
+{
+    ASSERT(m_ignoreUpdate);
+    --m_ignoreUpdate;
+    if (!m_ignoreUpdate && mediaElement().inActiveDocument())
+        updateActiveCues(mediaElement().currentTime());
+}
+
+DEFINE_TRACE(CueTimeline)
+{
+    visitor->trace(m_mediaElement);
+}
+
+} // namespace blink