Hook up Android closed captions 'enabled' setting to Blink

Source/core/html/track/AutomaticTrackSelection.cpp

Index: Source/core/html/track/AutomaticTrackSelection.cpp
diff --git a/Source/core/html/track/AutomaticTrackSelection.cpp b/Source/core/html/track/AutomaticTrackSelection.cpp
index 925a3bea2e6ab542bdcb36d668a97a59d13ab080..e912e671d65c36b796f9c63981a45ebff07882bc 100644
--- a/Source/core/html/track/AutomaticTrackSelection.cpp
+++ b/Source/core/html/track/AutomaticTrackSelection.cpp
@@ -15,7 +15,8 @@ class TrackGroup {
     STACK_ALLOCATED();
 public:
     enum GroupKind {
-        CaptionsAndSubtitles,
+        Captions,
+        Subtitles,
         Description,
         Chapter,
         Metadata
@@ -60,18 +61,21 @@ static int textTrackSelectionScore(const TextTrack& track)
 AutomaticTrackSelection::AutomaticTrackSelection(const Configuration& configuration)
     : m_configuration(configuration)
 {
+    fallbackCaptionOrSubtitleTrack = nullptr;

[fs, 2015/06/23 09:23:58]

Do this in the initializer list instead.

[srivats, 2015/06/24 01:40:19]

Done.

 }
 
-void AutomaticTrackSelection::performAutomaticTextTrackSelection(const TrackGroup& group)
+RefPtrWillBeRawPtr<TextTrack> AutomaticTrackSelection::performAutomaticTextTrackSelection(const TrackGroup& group)
 {
     ASSERT(group.tracks.size());
 
     // First, find the track in the group that should be enabled (if any).
     WillBeHeapVector<RefPtrWillBeMember<TextTrack>> currentlyEnabledTracks;
-    RefPtrWillBeRawPtr<TextTrack> trackToEnable = nullptr;
+    RefPtrWillBeRawPtr<TextTrack> preferredTrack = nullptr;
     RefPtrWillBeRawPtr<TextTrack> defaultTrack = nullptr;
-    RefPtrWillBeRawPtr<TextTrack> fallbackTrack = nullptr;
+
     int highestTrackScore = 0;
+    int highestDefaultTrackScore = 0;
+
     for (size_t i = 0; i < group.tracks.size(); ++i) {
         RefPtrWillBeRawPtr<TextTrack> textTrack = group.tracks[i];
 
@@ -80,24 +84,22 @@ void AutomaticTrackSelection::performAutomaticTextTrackSelection(const TrackGrou
 
         int trackScore = textTrackSelectionScore(*textTrack);
         if (trackScore) {
-            // * If the text track kind is { [subtitles or captions] [descriptions] } and the user has indicated an interest in having a
+            // * If the text track kind is subtitles or captions and the user has indicated an interest in having a
             // track with this text track kind, text track language, and text track label enabled, and there is no
             // other text track in the media element's list of text tracks with a text track kind of either subtitles
             // or captions whose text track mode is showing
-            // ...
-            // * If the text track kind is chapters and the text track language is one that the user agent has reason
-            // to believe is appropriate for the user, and there is no other text track in the media element's list of
-            // text tracks with a text track kind of chapters whose text track mode is showing
             //    Let the text track mode be showing.
+
             if (trackScore > highestTrackScore) {
+                preferredTrack = textTrack;
                 highestTrackScore = trackScore;
-                trackToEnable = textTrack;
+                fallbackCaptionOrSubtitleTrack = textTrack;
             }
-
-            if (!defaultTrack && textTrack->isDefault())
+            // Keep track of the highest scoring default track
+            if (trackScore > highestDefaultTrackScore && textTrack->isDefault()) {

[fs, 2015/06/23 09:23:58]

I don't think there's a need to track score for 'default' tracks - the old way
of doing it is probably fine.

I think the spec [1] says that all 'default' tracks should be enabled, but we
can probably keep the "first 'default'" behavior for now.

(I also think that's been done already in the "gather" phase of perform().)

[1] https://html.spec.whatwg.org/#perform-automatic-text-track-selection

[srivats, 2015/06/24 01:40:19]

Done.

+                highestDefaultTrackScore = trackScore;
                 defaultTrack = textTrack;
-            if (!defaultTrack && !fallbackTrack)
-                fallbackTrack = textTrack;
+            }
         } else if (!group.visibleTrack && !defaultTrack && textTrack->isDefault()) {
             // * If the track element has a default attribute specified, and there is no other text track in the media
             // element's list of text tracks whose text track mode is showing or showing by default
@@ -106,27 +108,24 @@ void AutomaticTrackSelection::performAutomaticTextTrackSelection(const TrackGrou
         }
     }
 
-    if (!trackToEnable && defaultTrack)
-        trackToEnable = defaultTrack;
-
-    // If no track matches the user's preferred language and non was marked 'default', enable the first track
-    // because the user has explicitly stated a preference for this kind of track.
-    if (!fallbackTrack && m_configuration.forceEnableSubtitleOrCaptionTrack && group.kind == TrackGroup::CaptionsAndSubtitles)
-        fallbackTrack = group.tracks[0];
-
-    if (!trackToEnable && fallbackTrack)
-        trackToEnable = fallbackTrack;
+    if (!preferredTrack && defaultTrack)
+        preferredTrack = defaultTrack;
 
     if (currentlyEnabledTracks.size()) {
         for (size_t i = 0; i < currentlyEnabledTracks.size(); ++i) {
             RefPtrWillBeRawPtr<TextTrack> textTrack = currentlyEnabledTracks[i];
-            if (textTrack != trackToEnable)
-                textTrack->setMode(TextTrack::disabledKeyword());
+            textTrack->setMode(TextTrack::disabledKeyword());
         }
     }
 
-    if (trackToEnable)
-        trackToEnable->setMode(TextTrack::showingKeyword());
+    // Set the default track to showing if group kind is not subtitles or captions.
+    if (defaultTrack && group.kind != TrackGroup::Captions && group.kind != TrackGroup::Subtitles)
+        defaultTrack->setMode(TextTrack::showingKeyword());
+
+    if (m_configuration.textTrackKindUserPreference == TextTrackKindUserPreference::Default)
+        return defaultTrack;
+
+    return preferredTrack;
 }
 
 void AutomaticTrackSelection::enableDefaultMetadataTextTracks(const TrackGroup& group)
@@ -150,7 +149,8 @@ void AutomaticTrackSelection::enableDefaultMetadataTextTracks(const TrackGroup&
 
 void AutomaticTrackSelection::perform(TextTrackList& textTracks)
 {
-    TrackGroup captionAndSubtitleTracks(TrackGroup::CaptionsAndSubtitles);
+    TrackGroup captionTracks(TrackGroup::Captions);
+    TrackGroup subtitleTracks(TrackGroup::Subtitles);
     TrackGroup descriptionTracks(TrackGroup::Description);
     TrackGroup chapterTracks(TrackGroup::Chapter);
     TrackGroup metadataTracks(TrackGroup::Metadata);
@@ -162,8 +162,10 @@ void AutomaticTrackSelection::perform(TextTrackList& textTracks)
 
         String kind = textTrack->kind();
         TrackGroup* currentGroup;
-        if (kind == TextTrack::subtitlesKeyword() || kind == TextTrack::captionsKeyword()) {
-            currentGroup = &captionAndSubtitleTracks;
+        if (kind == TextTrack::captionsKeyword()) {
+            currentGroup = &captionTracks;
+        } else if (kind == TextTrack::subtitlesKeyword()) {
+            currentGroup = &subtitleTracks;
         } else if (kind == TextTrack::descriptionsKeyword()) {
             currentGroup = &descriptionTracks;
         } else if (kind == TextTrack::chaptersKeyword()) {
@@ -192,14 +194,61 @@ void AutomaticTrackSelection::perform(TextTrackList& textTracks)
         currentGroup->tracks.append(textTrack);
     }
 
-    if (captionAndSubtitleTracks.tracks.size())
-        performAutomaticTextTrackSelection(captionAndSubtitleTracks);
+    RefPtrWillBeRawPtr<TextTrack> preferredSubtitleTrack = nullptr;

[fs, 2015/06/23 09:23:58]

Move this down to just before the "if (subtitleTracks..."

[srivats, 2015/06/24 01:40:19]

Done.

+    RefPtrWillBeRawPtr<TextTrack> preferredCaptionTrack = nullptr;
+    if (captionTracks.tracks.size()) {
+        preferredCaptionTrack = performAutomaticTextTrackSelection(captionTracks);
+        if (!fallbackCaptionOrSubtitleTrack)

[fs, 2015/06/23 09:23:58]

Looks like we could do this when actually needed - i.e. together with the
forceEnableSubtitleOrCaptionTrack check below - it appears selecting the
"fallback to the fallback" needn't be done at this point in time.

[srivats, 2015/06/24 01:40:19]

Done.

+            fallbackCaptionOrSubtitleTrack = captionTracks.tracks[0];
+    }
+    if (subtitleTracks.tracks.size()) {
+        preferredSubtitleTrack = performAutomaticTextTrackSelection(subtitleTracks);
+        if (!fallbackCaptionOrSubtitleTrack)
+            fallbackCaptionOrSubtitleTrack = subtitleTracks.tracks[0];
+    }
     if (descriptionTracks.tracks.size())
         performAutomaticTextTrackSelection(descriptionTracks);
     if (chapterTracks.tracks.size())
         performAutomaticTextTrackSelection(chapterTracks);
     if (metadataTracks.tracks.size())
         enableDefaultMetadataTextTracks(metadataTracks);
+
+    RefPtrWillBeRawPtr<TextTrack> trackToEnable =
+        enableTrackBasedOnUserPreference(preferredCaptionTrack, preferredSubtitleTrack);
+    if (m_configuration.forceEnableSubtitleOrCaptionTrack && !trackToEnable && fallbackCaptionOrSubtitleTrack)
+        trackToEnable = fallbackCaptionOrSubtitleTrack;
+
+    if (trackToEnable)
+        trackToEnable->setMode(TextTrack::showingKeyword());
+}
+
+RefPtrWillBeRawPtr<TextTrack> AutomaticTrackSelection::enableTrackBasedOnUserPreference(
+    RefPtrWillBeRawPtr<TextTrack> preferredCaptionTrack, RefPtrWillBeRawPtr<TextTrack> preferredSubtitleTrack)
+{
+    RefPtrWillBeRawPtr<TextTrack> trackToEnable = nullptr;
+    switch (m_configuration.textTrackKindUserPreference) {
+    case TextTrackKindUserPreference::Subtitles:
+        if (preferredSubtitleTrack)
+            trackToEnable = preferredSubtitleTrack;
+        break;
+    case TextTrackKindUserPreference::Default:
+    case TextTrackKindUserPreference::Captions:
+        // When the user prefers captions, display a caption track if present in user's preferred language.
+        // If no captions track exists in the user's preferred language or a subtitle track
+        // exists in a language with a higher score, display the subtitle track.
+        int captionTrackScore = 0;
+        int subtitleTrackScore = 0;
+        if (preferredCaptionTrack)
+            captionTrackScore = textTrackSelectionScore(*preferredCaptionTrack);
+        if (preferredSubtitleTrack)
+            subtitleTrackScore = textTrackSelectionScore(*preferredSubtitleTrack);
+        if (captionTrackScore >= subtitleTrackScore && preferredCaptionTrack)
+            trackToEnable = preferredCaptionTrack;
+        else if (preferredSubtitleTrack)
+            trackToEnable = preferredSubtitleTrack;
+        break;
+    }
+    return trackToEnable;
 }
 
 } // namespace blink