Add tate-chu-yoko support to TtmlDecoder

PiperOrigin-RevId: 292161845

RELEASENOTES.md

@@ -19,6 +19,8 @@
     later).
   * Parse `text-combine-upright` CSS property (i.e. tate-chu-yoko) in WebVTT
     subtitles (rendering is coming later).
+  * Parse `tts:combineText` property (i.e. tate-chu-yoko) in TTML subtitles
+    (rendering is coming later).
 * DRM: Add support for attaching DRM sessions to clear content in the demo app.
 * Downloads: Merge downloads in `SegmentDownloader` to improve overall download
   speed ([#5978](https://github.com/google/ExoPlayer/issues/5978)).

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

@@ -524,6 +524,19 @@ public final class TtmlDecoder extends SimpleSubtitleDecoder {
               break;
           }
           break;
+        case TtmlNode.ATTR_TTS_TEXT_COMBINE:
+          switch (Util.toLowerInvariant(attributeValue)) {
+            case TtmlNode.COMBINE_NONE:
+              style = createIfNull(style).setTextCombine(false);
+              break;
+            case TtmlNode.COMBINE_ALL:
+              style = createIfNull(style).setTextCombine(true);
+              break;
+            default:
+              // ignore
+              break;
+          }
+          break;
         case TtmlNode.ATTR_TTS_TEXT_DECORATION:
           switch (Util.toLowerInvariant(attributeValue)) {
             case TtmlNode.LINETHROUGH:

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

@@ -66,6 +66,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   public static final String ATTR_TTS_COLOR = "color";
   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 textDecoration
@@ -83,6 +84,10 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   public static final String START = "start";
   public static final String END = "end";
 
+  // Values for textCombine
+  public static final String COMBINE_NONE = "none";
+  public static final String COMBINE_ALL = "all";
+
   // Values for writingMode
   public static final String VERTICAL = "tb";
   public static final String VERTICAL_LR = "tblr";

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

@@ -29,6 +29,7 @@ import android.text.style.TypefaceSpan;
 import android.text.style.UnderlineSpan;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.text.SpanUtil;
+import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
 import java.util.Map;
 
 /**
@@ -116,6 +117,14 @@ import java.util.Map;
           end,
           Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
     }
+    if (style.getTextCombine()) {
+      SpanUtil.addOrReplaceSpan(
+          builder,
+          new HorizontalTextInVerticalContextSpan(),
+          start,
+          end,
+          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
     switch (style.getFontSizeUnit()) {
       case TtmlStyle.FONT_SIZE_UNIT_PIXEL:
         SpanUtil.addOrReplaceSpan(

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

@@ -75,6 +75,7 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
   private float fontSize;
   private @MonotonicNonNull String id;
   private Layout.@MonotonicNonNull Alignment textAlign;
+  @OptionalBoolean private int textCombine;
   @Cue.VerticalType private int verticalType;
 
   public TtmlStyle() {
@@ -216,6 +217,9 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       if (textAlign == null && ancestor.textAlign != null) {
         textAlign = ancestor.textAlign;
       }
+      if (textCombine == UNSPECIFIED) {
+        textCombine = ancestor.textCombine;
+      }
       if (fontSizeUnit == UNSPECIFIED) {
         fontSizeUnit = ancestor.fontSizeUnit;
         fontSize = ancestor.fontSize;
@@ -251,6 +255,16 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     return this;
   }
 
+  /** Returns true if the source entity has {@code tts:textCombine=all}. */
+  public boolean getTextCombine() {
+    return textCombine == ON;
+  }
+
+  public TtmlStyle setTextCombine(boolean combine) {
+    this.textCombine = combine ? ON : OFF;
+    return this;
+  }
+
   public TtmlStyle setFontSize(float fontSize) {
     this.fontSize = fontSize;
     return this;

library/core/src/test/assets/ttml/text_combine.xml

+<!--
+  ~ 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>
+      <p begin="10s" end="18s">Text with <span tts:textCombine="all">combined</span> section.</p>
+    </div>
+    <div>
+      <p begin="20s" end="28s">Text with <span tts:textCombine="none">un-combined</span> section.</p>
+    </div>
+    <div>
+      <p begin="30s" end="38s">"No textCombine"</p>
+    </div>
+  </body>
+</tt>

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

@@ -60,6 +60,7 @@ public final class TtmlDecoderTest {
   private static final String BITMAP_PIXEL_REGION_FILE = "ttml/bitmap_pixel_region.xml";
   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";
 
   @Test
   public void testInlineAttributes() throws IOException, SubtitleDecoderException {
@@ -587,6 +588,24 @@ public final class TtmlDecoderTest {
     assertThat(thirdCue.verticalType).isEqualTo(Cue.TYPE_UNSET);
   }
 
+  @Test
+  public void testTextCombine() throws IOException, SubtitleDecoderException {
+    TtmlSubtitle subtitle = getSubtitle(TEXT_COMBINE_FILE);
+
+    Spanned firstCue = getOnlyCueTextAtTimeUs(subtitle, 10_000_000);
+    assertThat(firstCue)
+        .hasHorizontalTextInVerticalContextSpanBetween(
+            "text with ".length(), "text with combined".length());
+
+    Spanned secondCue = getOnlyCueTextAtTimeUs(subtitle, 20_000_000);
+    assertThat(secondCue)
+        .hasNoHorizontalTextInVerticalContextSpanBetween(
+            "text with ".length(), "text with un-combined".length());
+
+    Spanned thirdCue = getOnlyCueTextAtTimeUs(subtitle, 30_000_000);
+    assertThat(thirdCue).hasNoHorizontalTextInVerticalContextSpanBetween(0, thirdCue.length());
+  }
+
   private static Spanned getOnlyCueTextAtTimeUs(Subtitle subtitle, long timeUs) {
     Cue cue = getOnlyCueAtTimeUs(subtitle, timeUs);
     assertThat(cue.text).isInstanceOf(Spanned.class);