Add ruby support to TtmlDecoder

I had to expand the info that gets passed around a bit, so I could join up the container, base & text ruby nodes.

Spec: https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-ruby
PiperOrigin-RevId: 295931653

RELEASENOTES.md

@@ -49,6 +49,8 @@
   * Catch-and-log all fatal exceptions in `TextRenderer` instead of re-throwing,
     allowing playback to continue even if subtitles fail
     ([#6885](https://github.com/google/ExoPlayer/issues/6885)).
+  * Parse `tts:ruby` and `tts:rubyPosition` properties in TTML subtitles
+    (rendering is coming later).
 * DRM:
   * Add support for attaching DRM sessions to clear content in the demo app.
   * Remove `DrmSessionManager` references from all renderers.

library/core/src/main/java/com/google/android/exoplayer2/text/ttml/DeleteTextSpan.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package com.google.android.exoplayer2.text.ttml;
+
+import android.text.Spanned;
+
+/**
+ * A span used to mark a section of text for later deletion.
+ *
+ * <p>This is deliberately package-private because it's not generally supported by Android and
+ * results in surprising behaviour when simply calling {@link Spanned#toString} (i.e. the text isn't
+ * deleted).
+ *
+ * <p>This span is explicitly handled in {@code TtmlNode#cleanUpText}.
+ */
+/* package */ final class DeleteTextSpan {}

library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlDecoder.java

@@ -22,6 +22,7 @@ import com.google.android.exoplayer2.text.Cue;
 import com.google.android.exoplayer2.text.SimpleSubtitleDecoder;
 import com.google.android.exoplayer2.text.Subtitle;
 import com.google.android.exoplayer2.text.SubtitleDecoderException;
+import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.ColorParser;
 import com.google.android.exoplayer2.util.Log;
@@ -537,6 +538,40 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
               break;
           }
           break;
+        case TtmlNode.ATTR_TTS_RUBY:
+          switch (Util.toLowerInvariant(attributeValue)) {
+            case TtmlNode.RUBY_CONTAINER:
+              style = createIfNull(style).setRubyType(TtmlStyle.RUBY_TYPE_CONTAINER);
+              break;
+            case TtmlNode.RUBY_BASE:
+            case TtmlNode.RUBY_BASE_CONTAINER:
+              style = createIfNull(style).setRubyType(TtmlStyle.RUBY_TYPE_BASE);
+              break;
+            case TtmlNode.RUBY_TEXT:
+            case TtmlNode.RUBY_TEXT_CONTAINER:
+              style = createIfNull(style).setRubyType(TtmlStyle.RUBY_TYPE_TEXT);
+              break;
+            case TtmlNode.RUBY_DELIMITER:
+              style = createIfNull(style).setRubyType(TtmlStyle.RUBY_TYPE_DELIMITER);
+              break;
+            default:
+              // ignore
+              break;
+          }
+          break;
+        case TtmlNode.ATTR_TTS_RUBY_POSITION:
+          switch (Util.toLowerInvariant(attributeValue)) {
+            case TtmlNode.RUBY_BEFORE:
+              style = createIfNull(style).setRubyPosition(RubySpan.POSITION_OVER);
+              break;
+            case TtmlNode.RUBY_AFTER:
+              style = createIfNull(style).setRubyPosition(RubySpan.POSITION_UNDER);
+              break;
+            default:
+              // ignore
+              break;
+          }
+          break;
         case TtmlNode.ATTR_TTS_TEXT_DECORATION:
           switch (Util.toLowerInvariant(attributeValue)) {
             case TtmlNode.LINETHROUGH:
@@ -650,8 +685,9 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
         endTime = parent.endTimeUs;
       }
     }
+
     return TtmlNode.buildNode(
-        parser.getName(), startTime, endTime, style, styleIds, regionId, imageId);
+        parser.getName(), startTime, endTime, style, styleIds, regionId, imageId, parent);
   }
 
   private static boolean isSupportedTag(String tag) {

library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlNode.java

@@ -64,11 +64,24 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   public static final String ATTR_TTS_FONT_FAMILY = "fontFamily";
   public static final String ATTR_TTS_FONT_WEIGHT = "fontWeight";
   public static final String ATTR_TTS_COLOR = "color";
+  public static final String ATTR_TTS_RUBY = "ruby";
+  public static final String ATTR_TTS_RUBY_POSITION = "rubyPosition";
   public static final String ATTR_TTS_TEXT_DECORATION = "textDecoration";
   public static final String ATTR_TTS_TEXT_ALIGN = "textAlign";
   public static final String ATTR_TTS_TEXT_COMBINE = "textCombine";
   public static final String ATTR_TTS_WRITING_MODE = "writingMode";
 
+  // Values for ruby
+  public static final String RUBY_CONTAINER = "container";
+  public static final String RUBY_BASE = "base";
+  public static final String RUBY_BASE_CONTAINER = "baseContainer";
+  public static final String RUBY_TEXT = "text";
+  public static final String RUBY_TEXT_CONTAINER = "textContainer";
+  public static final String RUBY_DELIMITER = "delimiter";
+
+  // Values for rubyPosition
+  public static final String RUBY_BEFORE = "before";
+  public static final String RUBY_AFTER = "after";
   // Values for textDecoration
   public static final String LINETHROUGH = "linethrough";
   public static final String NO_LINETHROUGH = "nolinethrough";
@@ -102,6 +115,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   @Nullable private final String[] styleIds;
   public final String regionId;
   @Nullable public final String imageId;
+  @Nullable public final TtmlNode parent;
 
   private final HashMap<String, Integer> nodeStartsByRegion;
   private final HashMap<String, Integer> nodeEndsByRegion;
@@ -117,7 +131,8 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         /* style= */ null,
         /* styleIds= */ null,
         ANONYMOUS_REGION_ID,
-        /* imageId= */ null);
+        /* imageId= */ null,
+        /* parent= */ null);
   }
 
   public static TtmlNode buildNode(
@@ -127,9 +142,10 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       @Nullable TtmlStyle style,
       @Nullable String[] styleIds,
       String regionId,
-      @Nullable String imageId) {
+      @Nullable String imageId,
+      @Nullable TtmlNode parent) {
     return new TtmlNode(
-        tag, /* text= */ null, startTimeUs, endTimeUs, style, styleIds, regionId, imageId);
+        tag, /* text= */ null, startTimeUs, endTimeUs, style, styleIds, regionId, imageId, parent);
   }
 
   private TtmlNode(
@@ -140,7 +156,8 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       @Nullable TtmlStyle style,
       @Nullable String[] styleIds,
       String regionId,
-      @Nullable String imageId) {
+      @Nullable String imageId,
+      @Nullable TtmlNode parent) {
     this.tag = tag;
     this.text = text;
     this.imageId = imageId;
@@ -150,6 +167,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     this.startTimeUs = startTimeUs;
     this.endTimeUs = endTimeUs;
     this.regionId = Assertions.checkNotNull(regionId);
+    this.parent = parent;
     nodeStartsByRegion = new HashMap<>();
     nodeEndsByRegion = new HashMap<>();
   }
@@ -361,14 +379,19 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       regionOutput.setText(text);
     }
     if (resolvedStyle != null) {
-      TtmlRenderUtil.applyStylesToSpan(text, start, end, resolvedStyle);
+      TtmlRenderUtil.applyStylesToSpan(text, start, end, resolvedStyle, parent);
       regionOutput.setVerticalType(resolvedStyle.getVerticalType());
     }
   }
 
   private static void cleanUpText(SpannableStringBuilder builder) {
     // Having joined the text elements, we need to do some final cleanup on the result.
-    // 1. Collapse multiple consecutive spaces into a single space.
+    // Remove any text covered by a DeleteTextSpan (e.g. ruby text).
+    DeleteTextSpan[] deleteTextSpans = builder.getSpans(0, builder.length(), DeleteTextSpan.class);
+    for (DeleteTextSpan deleteTextSpan : deleteTextSpans) {
+      builder.replace(builder.getSpanStart(deleteTextSpan), builder.getSpanEnd(deleteTextSpan), "");
+    }
+    // Collapse multiple consecutive spaces into a single space.
     for (int i = 0; i < builder.length(); i++) {
       if (builder.charAt(i) == ' ') {
         int j = i + 1;
@@ -381,7 +404,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         }
       }
     }
-    // 2. Remove any spaces from the start of each line.
+    // Remove any spaces from the start of each line.
     if (builder.length() > 0 && builder.charAt(0) == ' ') {
       builder.delete(0, 1);
     }
@@ -390,7 +413,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         builder.delete(i + 1, i + 2);
       }
     }
-    // 3. Remove any spaces from the end of each line.
+    // Remove any spaces from the end of each line.
     if (builder.length() > 0 && builder.charAt(builder.length() - 1) == ' ') {
       builder.delete(builder.length() - 1, builder.length());
     }
@@ -399,7 +422,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
         builder.delete(i, i + 1);
       }
     }
-    // 4. Trim a trailing newline, if there is one.
+    // Trim a trailing newline, if there is one.
     if (builder.length() > 0 && builder.charAt(builder.length() - 1) == '\n') {
       builder.delete(builder.length() - 1, builder.length());
     }

library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlRenderUtil.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.text.ttml;
 
 import android.text.Layout.Alignment;
+import android.text.Spannable;
 import android.text.SpannableStringBuilder;
 import android.text.Spanned;
 import android.text.style.AbsoluteSizeSpan;
@@ -29,7 +30,12 @@ import android.text.style.TypefaceSpan;
 import android.text.style.UnderlineSpan;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
+import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.android.exoplayer2.text.span.SpanUtil;
+import com.google.android.exoplayer2.util.Log;
+import com.google.android.exoplayer2.util.Util;
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.Map;
 
 /**
@@ -37,6 +43,8 @@ import java.util.Map;
  */
 /* package */ final class TtmlRenderUtil {
 
+  private static final String TAG = "TtmlRenderUtil";
+
   @Nullable
   public static TtmlStyle resolveStyle(
       @Nullable TtmlStyle style, @Nullable String[] styleIds, Map<String, TtmlStyle> globalStyles) {
@@ -71,8 +79,8 @@ import java.util.Map;
     return style;
   }
 
-  public static void applyStylesToSpan(SpannableStringBuilder builder,
-      int start, int end, TtmlStyle style) {
+  public static void applyStylesToSpan(
+      Spannable builder, int start, int end, TtmlStyle style, @Nullable TtmlNode parent) {
 
     if (style.getStyle() != TtmlStyle.UNSPECIFIED) {
       builder.setSpan(new StyleSpan(style.getStyle()), start, end,
@@ -108,6 +116,53 @@ import java.util.Map;
           end,
           Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
     }
+    switch (style.getRubyType()) {
+      case TtmlStyle.RUBY_TYPE_BASE:
+        // look for the sibling RUBY_TEXT and add it as span between start & end.
+        @Nullable TtmlNode containerNode = findRubyContainerNode(parent);
+        if (containerNode == null) {
+          // No matching container node
+          break;
+        }
+        @Nullable TtmlNode textNode = findRubyTextNode(containerNode);
+        if (textNode == null) {
+          // no matching text node
+          break;
+        }
+        String rubyText;
+        if (textNode.getChildCount() == 1 && textNode.getChild(0).text != null) {
+          rubyText = Util.castNonNull(textNode.getChild(0).text);
+        } else {
+          Log.i(TAG, "Skipping rubyText node without exactly one text child.");
+          break;
+        }
+
+        // TODO: Get rubyPosition from `textNode` when TTML inheritance is implemented.
+        @RubySpan.Position
+        int rubyPosition =
+            containerNode.style != null
+                ? containerNode.style.getRubyPosition()
+                : RubySpan.POSITION_UNKNOWN;
+        builder.setSpan(
+            new RubySpan(rubyText, rubyPosition), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+        break;
+      case TtmlStyle.RUBY_TYPE_DELIMITER:
+        // TODO: Add support for this when RubySpan supports parenthetical text. For now, just
+        // fall through and delete the text.
+      case TtmlStyle.RUBY_TYPE_TEXT:
+        // We can't just remove the text directly from `builder` here because TtmlNode has fixed
+        // ideas of where every node starts and ends (nodeStartsByRegion and nodeEndsByRegion) so
+        // all these indices become invalid if we mutate the underlying string at this point.
+        // Instead we add a special span that's then handled in TtmlNode#cleanUpText.
+        builder.setSpan(new DeleteTextSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+        break;
+      case TtmlStyle.RUBY_TYPE_CONTAINER:
+      case TtmlStyle.UNSPECIFIED:
+      default:
+        // Do nothing
+        break;
+    }
+
     @Nullable Alignment textAlign = style.getTextAlign();
     if (textAlign != null) {
       SpanUtil.addOrReplaceSpan(
@@ -156,6 +211,35 @@ import java.util.Map;
     }
   }
 
+  @Nullable
+  private static TtmlNode findRubyTextNode(TtmlNode rubyContainerNode) {
+    Deque<TtmlNode> childNodesStack = new ArrayDeque<>();
+    childNodesStack.push(rubyContainerNode);
+    while (!childNodesStack.isEmpty()) {
+      TtmlNode childNode = childNodesStack.pop();
+      if (childNode.style != null && childNode.style.getRubyType() == TtmlStyle.RUBY_TYPE_TEXT) {
+        return childNode;
+      }
+      for (int i = childNode.getChildCount() - 1; i >= 0; i--) {
+        childNodesStack.push(childNode.getChild(i));
+      }
+    }
+
+    return null;
+  }
+
+  @Nullable
+  private static TtmlNode findRubyContainerNode(@Nullable TtmlNode node) {
+    while (node != null) {
+      @Nullable TtmlStyle style = node.style;
+      if (style != null && style.getRubyType() == TtmlStyle.RUBY_TYPE_CONTAINER) {
+        return node;
+      }
+      node = node.parent;
+    }
+    return null;
+  }
+
   /**
    * Called when the end of a paragraph is encountered. Adds a newline if there are one or more
    * non-space characters since the previous newline.

library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlStyle.java

@@ -21,6 +21,7 @@ import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.text.Cue;
 import com.google.android.exoplayer2.text.Cue.VerticalType;
+import com.google.android.exoplayer2.text.span.RubySpan;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -61,6 +62,16 @@ import java.lang.annotation.RetentionPolicy;
   private static final int OFF = 0;
   private static final int ON = 1;
 
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({UNSPECIFIED, RUBY_TYPE_CONTAINER, RUBY_TYPE_BASE, RUBY_TYPE_TEXT, RUBY_TYPE_DELIMITER})
+  public @interface RubyType {}
+
+  public static final int RUBY_TYPE_CONTAINER = 1;
+  public static final int RUBY_TYPE_BASE = 2;
+  public static final int RUBY_TYPE_TEXT = 3;
+  public static final int RUBY_TYPE_DELIMITER = 4;
+
   @Nullable private String fontFamily;
   private int fontColor;
   private boolean hasFontColor;
@@ -73,6 +84,8 @@ import java.lang.annotation.RetentionPolicy;
   @FontSizeUnit private int fontSizeUnit;
   private float fontSize;
   @Nullable private String id;
+  @RubyType private int rubyType;
+  @RubySpan.Position private int rubyPosition;
   @Nullable private Layout.Alignment textAlign;
   @OptionalBoolean private int textCombine;
   @Cue.VerticalType private int verticalType;
@@ -83,6 +96,8 @@ import java.lang.annotation.RetentionPolicy;
     bold = UNSPECIFIED;
     italic = UNSPECIFIED;
     fontSizeUnit = UNSPECIFIED;
+    rubyType = UNSPECIFIED;
+    rubyPosition = RubySpan.POSITION_UNKNOWN;
     textCombine = UNSPECIFIED;
     verticalType = Cue.TYPE_UNSET;
   }
@@ -214,6 +229,9 @@ import java.lang.annotation.RetentionPolicy;
       if (underline == UNSPECIFIED) {
         underline = ancestor.underline;
       }
+      if (rubyPosition == RubySpan.POSITION_UNKNOWN) {
+        rubyPosition = ancestor.rubyPosition;
+      }
       if (textAlign == null && ancestor.textAlign != null) {
         textAlign = ancestor.textAlign;
       }
@@ -228,8 +246,11 @@ import java.lang.annotation.RetentionPolicy;
       if (chaining && !hasBackgroundColor && ancestor.hasBackgroundColor) {
         setBackgroundColor(ancestor.backgroundColor);
       }
-      if (chaining && verticalType == Cue.TYPE_UNSET) {
-        verticalType = ancestor.verticalType;
+      if (chaining && rubyType == UNSPECIFIED && ancestor.rubyType != UNSPECIFIED) {
+        rubyType = ancestor.rubyType;
+      }
+      if (chaining && verticalType == Cue.TYPE_UNSET && ancestor.verticalType != Cue.TYPE_UNSET) {
+        setVerticalType(ancestor.verticalType);
       }
     }
     return this;
@@ -245,6 +266,26 @@ import java.lang.annotation.RetentionPolicy;
     return id;
   }
 
+  public TtmlStyle setRubyType(@RubyType int rubyType) {
+    this.rubyType = rubyType;
+    return this;
+  }
+
+  @RubyType
+  public int getRubyType() {
+    return rubyType;
+  }
+
+  public TtmlStyle setRubyPosition(@RubySpan.Position int position) {
+    this.rubyPosition = position;
+    return this;
+  }
+
+  @RubySpan.Position
+  public int getRubyPosition() {
+    return rubyPosition;
+  }
+
   @Nullable
   public Layout.Alignment getTextAlign() {
     return textAlign;

library/core/src/test/java/com/google/android/exoplayer2/text/ttml/TtmlDecoderTest.java

@@ -27,6 +27,7 @@ import com.google.android.exoplayer2.testutil.TestUtil;
 import com.google.android.exoplayer2.text.Cue;
 import com.google.android.exoplayer2.text.Subtitle;
 import com.google.android.exoplayer2.text.SubtitleDecoderException;
+import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.ColorParser;
 import java.io.IOException;
@@ -61,6 +62,7 @@ public final class TtmlDecoderTest {
   private static final String BITMAP_UNSUPPORTED_REGION_FILE = "ttml/bitmap_unsupported_region.xml";
   private static final String VERTICAL_TEXT_FILE = "ttml/vertical_text.xml";
   private static final String TEXT_COMBINE_FILE = "ttml/text_combine.xml";
+  private static final String RUBIES_FILE = "ttml/rubies.xml";
 
   @Test
   public void testInlineAttributes() throws IOException, SubtitleDecoderException {
@@ -606,6 +608,38 @@ public final class TtmlDecoderTest {
     assertThat(thirdCue).hasNoHorizontalTextInVerticalContextSpanBetween(0, thirdCue.length());
   }
 
+  @Test
+  public void testRubies() throws IOException, SubtitleDecoderException {
+    TtmlSubtitle subtitle = getSubtitle(RUBIES_FILE);
+
+    Spanned firstCue = getOnlyCueTextAtTimeUs(subtitle, 10_000_000);
+    assertThat(firstCue.toString()).isEqualTo("Cue with annotated text.");
+    assertThat(firstCue)
+        .hasRubySpanBetween("Cue with ".length(), "Cue with annotated".length())
+        .withTextAndPosition("1st rubies", RubySpan.POSITION_OVER);
+    assertThat(firstCue)
+        .hasRubySpanBetween("Cue with annotated ".length(), "Cue with annotated text".length())
+        .withTextAndPosition("2nd rubies", RubySpan.POSITION_UNKNOWN);
+
+    Spanned secondCue = getOnlyCueTextAtTimeUs(subtitle, 20_000_000);
+    assertThat(secondCue.toString()).isEqualTo("Cue with annotated text.");
+    assertThat(secondCue)
+        .hasRubySpanBetween("Cue with ".length(), "Cue with annotated".length())
+        .withTextAndPosition("rubies", RubySpan.POSITION_UNKNOWN);
+
+    Spanned thirdCue = getOnlyCueTextAtTimeUs(subtitle, 30_000_000);
+    assertThat(thirdCue.toString()).isEqualTo("Cue with annotated text.");
+    assertThat(thirdCue).hasNoRubySpanBetween(0, thirdCue.length());
+
+    Spanned fourthCue = getOnlyCueTextAtTimeUs(subtitle, 40_000_000);
+    assertThat(fourthCue.toString()).isEqualTo("Cue with text.");
+    assertThat(fourthCue).hasNoRubySpanBetween(0, fourthCue.length());
+
+    Spanned fifthCue = getOnlyCueTextAtTimeUs(subtitle, 50_000_000);
+    assertThat(fifthCue.toString()).isEqualTo("Cue with annotated text.");
+    assertThat(fifthCue).hasNoRubySpanBetween(0, fifthCue.length());
+  }
+
   private static Spanned getOnlyCueTextAtTimeUs(Subtitle subtitle, long timeUs) {
     Cue cue = getOnlyCueAtTimeUs(subtitle, timeUs);
     assertThat(cue.text).isInstanceOf(Spanned.class);

library/core/src/test/java/com/google/android/exoplayer2/text/ttml/TtmlStyleTest.java

@@ -29,6 +29,7 @@ import android.text.Layout;
 import androidx.annotation.ColorInt;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.text.Cue;
+import com.google.android.exoplayer2.text.span.RubySpan;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -42,6 +43,8 @@ public final class TtmlStyleTest {
   private static final float FONT_SIZE = 12.5f;
   @TtmlStyle.FontSizeUnit private static final int FONT_SIZE_UNIT = TtmlStyle.FONT_SIZE_UNIT_EM;
   @ColorInt private static final int BACKGROUND_COLOR = Color.BLACK;
+  private static final int RUBY_TYPE = TtmlStyle.RUBY_TYPE_TEXT;
+  private static final int RUBY_POSITION = RubySpan.POSITION_UNDER;
   private static final Layout.Alignment TEXT_ALIGN = Layout.Alignment.ALIGN_CENTER;
   private static final boolean TEXT_COMBINE = true;
   @Cue.VerticalType private static final int VERTICAL_TYPE = Cue.VERTICAL_TYPE_RL;
@@ -58,6 +61,8 @@ public final class TtmlStyleTest {
           .setFontFamily(FONT_FAMILY)
           .setFontSize(FONT_SIZE)
           .setFontSizeUnit(FONT_SIZE_UNIT)
+          .setRubyType(RUBY_TYPE)
+          .setRubyPosition(RUBY_POSITION)
           .setTextAlign(TEXT_ALIGN)
           .setTextCombine(TEXT_COMBINE)
           .setVerticalType(VERTICAL_TYPE);
@@ -75,8 +80,12 @@ public final class TtmlStyleTest {
     assertThat(style.getFontColor()).isEqualTo(FONT_COLOR);
     assertThat(style.getFontSize()).isEqualTo(FONT_SIZE);
     assertThat(style.getFontSizeUnit()).isEqualTo(FONT_SIZE_UNIT);
+    assertThat(style.getRubyPosition()).isEqualTo(RUBY_POSITION);
     assertThat(style.getTextAlign()).isEqualTo(TEXT_ALIGN);
     assertThat(style.getTextCombine()).isEqualTo(TEXT_COMBINE);
+    assertWithMessage("rubyType should not be inherited")
+        .that(style.getRubyType())
+        .isEqualTo(UNSPECIFIED);
     assertWithMessage("backgroundColor should not be inherited")
         .that(style.hasBackgroundColor())
         .isFalse();
@@ -99,11 +108,13 @@ public final class TtmlStyleTest {
     assertThat(style.getFontColor()).isEqualTo(FONT_COLOR);
     assertThat(style.getFontSize()).isEqualTo(FONT_SIZE);
     assertThat(style.getFontSizeUnit()).isEqualTo(FONT_SIZE_UNIT);
+    assertThat(style.getRubyPosition()).isEqualTo(RUBY_POSITION);
     assertThat(style.getTextAlign()).isEqualTo(TEXT_ALIGN);
     assertThat(style.getTextCombine()).isEqualTo(TEXT_COMBINE);
     assertWithMessage("backgroundColor should be chained")
         .that(style.getBackgroundColor())
         .isEqualTo(BACKGROUND_COLOR);
+    assertWithMessage("rubyType should be chained").that(style.getRubyType()).isEqualTo(RUBY_TYPE);
     assertWithMessage("verticalType should be chained")
         .that(style.getVerticalType())
         .isEqualTo(VERTICAL_TYPE);
@@ -206,6 +217,24 @@ public final class TtmlStyleTest {
     assertThat(style.getId()).isNull();
   }
 
+  @Test
+  public void testRubyType() {
+    TtmlStyle style = new TtmlStyle();
+
+    assertThat(style.getRubyType()).isEqualTo(UNSPECIFIED);
+    style.setRubyType(TtmlStyle.RUBY_TYPE_BASE);
+    assertThat(style.getRubyType()).isEqualTo(TtmlStyle.RUBY_TYPE_BASE);
+  }
+
+  @Test
+  public void testRubyPosition() {
+    TtmlStyle style = new TtmlStyle();
+
+    assertThat(style.getRubyPosition()).isEqualTo(RubySpan.POSITION_UNKNOWN);
+    style.setRubyPosition(RubySpan.POSITION_OVER);
+    assertThat(style.getRubyPosition()).isEqualTo(RubySpan.POSITION_OVER);
+  }
+
   @Test
   public void testTextAlign() {
     TtmlStyle style = new TtmlStyle();

testdata/src/test/assets/ttml/rubies.xml

@@ -0,0 +1,78 @@
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  ~
+  -->
+<tt xmlns:ttm="http://www.w3.org/2006/10/ttaf1#metadata"
+  xmlns:ttp="http://www.w3.org/2006/10/ttaf1#parameter"
+  xmlns:tts="http://www.w3.org/2006/10/ttaf1#style"
+  xmlns="http://www.w3.org/ns/ttml"
+  xmlns="http://www.w3.org/2006/10/ttaf1">
+  <body>
+    <div>
+      <!-- Base before and after text, one with explicit position -->
+      <p begin="10s" end="18s">
+        Cue with
+        <span tts:ruby="container" tts:rubyPosition="before">
+          <span tts:ruby="base">annotated</span>
+          <span tts:ruby="text">1st rubies</span>
+        </span>
+        <span tts:ruby="container">
+          <span tts:ruby="text">2nd rubies</span>
+          <span tts:ruby="base">text</span>.
+        </span>
+      </p>
+    </div>
+    <div>
+      <!-- Delimiter (parenthetical) text is stripped -->
+      <p begin="20s" end="28s">
+        Cue with
+        <span tts:ruby="container">
+          <span tts:ruby="text">rubies</span>
+          <span tts:ruby="base">annotated</span>
+          <span tts:ruby="delimiter">alt-text</span>
+        </span>
+        text.
+      </p>
+    </div>
+    <div>
+      <!-- No text section -> no span -->
+      <p begin="30s" end="38s">
+        Cue with
+        <span tts:ruby="container" tts:rubyPosition="before">
+          <span tts:ruby="base">annotated</span>
+        </span>
+        text.</p>
+    </div>
+    <div>
+      <!-- No base section -> text still stripped-->
+      <p begin="40s" end="48s">
+        Cue with
+        <span tts:ruby="container" tts:rubyPosition="before">
+          <span tts:ruby="text">rubies</span>
+        </span>
+        text.
+      </p>
+    </div>
+    <div>
+      <!-- No container section -> text still stripped-->
+      <p begin="50s" end="58s">
+        Cue with
+        <span tts:ruby="text">rubies</span>
+        <span tts:ruby="base">annotated</span>
+        text.
+      </p>
+    </div>
+  </body>
+</tt>