Hook up Android closed captions 'enabled' setting to Blink

Source/core/html/track/AutomaticTrackSelection.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/AutomaticTrackSelection.h"
 
 #include "core/html/track/TextTrack.h"
 #include "core/html/track/TextTrackList.h"
 #include "platform/Language.h"
@@ skipping 53 matching lines @@
 
 void 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> defaultTrack = nullptr;
     RefPtrWillBeRawPtr<TextTrack> fallbackTrack = nullptr;
-    int highestTrackScore = 0;
+    RefPtrWillBeRawPtr<TextTrack> preferredCaptionTrack = nullptr;
+    RefPtrWillBeRawPtr<TextTrack> preferredSubtitleTrack = nullptr;
+
+    int highestCaptionTrackScore = 0;

[fs, 2015/06/09 16:03:57]

I'd think it would be possible to just use the value of the setting to "boost"
the score of a track based on the kind. Maybe only for tracks w/ score from the
language != 0.

[srivats, 2015/06/10 19:55:15]

I had to split the scores for track kinds to handle the case where user
preferred kind is captions and there is a subtitle track with a higher score.

[fs, 2015/06/11 10:46:05]

I'm a little uncomfortable with the increasing number of "loose" variables in
this function. It might make sense to split the current
"captionsAndSubtitlesTrack" into two, and then apply the score per group - and
then have the logic for actually choosing one or the other on a higher level.

+    int highestSubtitleTrackScore = 0;
+    int highestDefaultTrackScore = 0;
+
     for (size_t i = 0; i < group.tracks.size(); ++i) {
         RefPtrWillBeRawPtr<TextTrack> textTrack = group.tracks[i];
 
         if (m_configuration.disableCurrentlyEnabledTracks && textTrack->mode() == TextTrack::showingKeyword())
             currentlyEnabledTracks.append(textTrack);
 
         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) {
-                highestTrackScore = trackScore;
-                trackToEnable = textTrack;
+
+            if (textTrack->kind() == TextTrack::subtitlesKeyword() && trackScore > highestSubtitleTrackScore) {
+                preferredSubtitleTrack = textTrack;
+                highestSubtitleTrackScore = trackScore;
+            } else if (textTrack->kind() == TextTrack::captionsKeyword() && trackScore > highestCaptionTrackScore) {
+                preferredCaptionTrack = textTrack;
+                highestCaptionTrackScore = trackScore;
             }
 
-            if (!defaultTrack && textTrack->isDefault())
+            if (textTrack->isDefault() && trackScore > highestDefaultTrackScore) {
+                highestDefaultTrackScore = trackScore;
                 defaultTrack = textTrack;
-            if (!defaultTrack && !fallbackTrack)
-                fallbackTrack = textTrack;
+            }
+            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
             //    Let the text track mode be showing by default.
             defaultTrack = textTrack;
         }
     }
 
+    if (m_configuration.textTrackKindUserPreference == TextTrackKindUserPreference::Default && defaultTrack) {

[fs, 2015/06/09 16:03:57]

I think this might be better suited as a switch.

[srivats, 2015/06/10 19:55:15]

Agreed. I'll change it.

+        trackToEnable = defaultTrack;
+    } else if (m_configuration.textTrackKindUserPreference == TextTrackKindUserPreference::Subtitles && preferredSubtitleTrack) {
+        trackToEnable = preferredSubtitleTrack;
+    } else if (m_configuration.textTrackKindUserPreference == 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.
+        if (highestCaptionTrackScore >= highestSubtitleTrackScore && preferredCaptionTrack)
+            trackToEnable = preferredCaptionTrack;
+        else if (preferredSubtitleTrack)
+            trackToEnable = preferredSubtitleTrack;
+    }
+
     if (!trackToEnable && defaultTrack)
         trackToEnable = defaultTrack;
 
-    // If no track matches the user's preferred language and non was marked 'default', enable the first track
+    // If no track matches the user's preferred language and none 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 (!trackToEnable && m_configuration.forceEnableSubtitleOrCaptionTrack && group.kind == TrackGroup::CaptionsAndSubtitles) {
+        trackToEnable = fallbackTrack ? fallbackTrack : group.tracks[0];
+    }
 
     if (currentlyEnabledTracks.size()) {
         for (size_t i = 0; i < currentlyEnabledTracks.size(); ++i) {
             RefPtrWillBeRawPtr<TextTrack> textTrack = currentlyEnabledTracks[i];
             if (textTrack != trackToEnable)
                 textTrack->setMode(TextTrack::disabledKeyword());
         }
     }
 
     if (trackToEnable)
@@ skipping 67 matching lines @@
         performAutomaticTextTrackSelection(captionAndSubtitleTracks);
     if (descriptionTracks.tracks.size())
         performAutomaticTextTrackSelection(descriptionTracks);
     if (chapterTracks.tracks.size())
         performAutomaticTextTrackSelection(chapterTracks);
     if (metadataTracks.tracks.size())
         enableDefaultMetadataTextTracks(metadataTracks);
 }
 
 } // namespace blink