Add tate-chu-yoko support to WebVTT decoding

PiperOrigin-RevId: 288285953

RELEASENOTES.md

@@ -47,6 +47,8 @@
   next cue ([#6833](https://github.com/google/ExoPlayer/issues/6833)).
 * Parse \<ruby\> and \<rt\> tags in WebVTT subtitles (rendering is coming
   later).
+* Parse `text-combine-upright` CSS property (i.e. tate-chu-yoko) in WebVTT
+  subtitles (rendering is coming later).
 
 ### 2.11.1 (2019-12-20) ###
 

library/core/src/main/java/com/google/android/exoplayer2/text/span/HorizontalTextInVerticalContextSpan.java

+/*
+ * 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.span;
+
+/**
+ * A styling span for horizontal text in a vertical context.
+ *
+ * <p>This is used in vertical text to write some characters in a horizontal orientation, known in
+ * Japanese as tate-chu-yoko.
+ *
+ * <p>More information on <a
+ * href="https://www.w3.org/TR/jlreq/#handling_of_tatechuyoko">tate-chu-yoko</a> and <a
+ * href="https://developer.android.com/guide/topics/text/spans">span styling</a>.
+ */
+// NOTE: There's no Android layout support for this, so this span currently doesn't extend any
+// styling superclasses (e.g. MetricAffectingSpan). The only way to render this styling is to
+// extract the spans and do the layout manually.
+public final class HorizontalTextInVerticalContextSpan {}

library/core/src/main/java/com/google/android/exoplayer2/text/webvtt/CssParser.java

@@ -31,14 +31,19 @@ import java.util.regex.Pattern;
  */
 /* package */ final class CssParser {
 
+  private static final String TAG = "CssParser";
+
+  private static final String RULE_START = "{";
+  private static final String RULE_END = "}";
   private static final String PROPERTY_BGCOLOR = "background-color";
   private static final String PROPERTY_FONT_FAMILY = "font-family";
   private static final String PROPERTY_FONT_WEIGHT = "font-weight";
+  private static final String PROPERTY_TEXT_COMBINE_UPRIGHT = "text-combine-upright";
+  private static final String VALUE_ALL = "all";
+  private static final String VALUE_DIGITS = "digits";
   private static final String PROPERTY_TEXT_DECORATION = "text-decoration";
   private static final String VALUE_BOLD = "bold";
   private static final String VALUE_UNDERLINE = "underline";
-  private static final String RULE_START = "{";
-  private static final String RULE_END = "}";
   private static final String PROPERTY_FONT_STYLE = "font-style";
   private static final String VALUE_ITALIC = "italic";
 
@@ -182,6 +187,8 @@ import java.util.regex.Pattern;
       style.setFontColor(ColorParser.parseCssColor(value));
     } else if (PROPERTY_BGCOLOR.equals(property)) {
       style.setBackgroundColor(ColorParser.parseCssColor(value));
+    } else if (PROPERTY_TEXT_COMBINE_UPRIGHT.equals(property)) {
+      style.setCombineUpright(VALUE_ALL.equals(value) || value.startsWith(VALUE_DIGITS));
     } else if (PROPERTY_TEXT_DECORATION.equals(property)) {
       if (VALUE_UNDERLINE.equals(value)) {
         style.setUnderline(true);

library/core/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCssStyle.java

@@ -95,6 +95,7 @@ public final class WebvttCssStyle {
   @FontSizeUnit private int fontSizeUnit;
   private float fontSize;
   @Nullable private Layout.Alignment textAlign;
+  private boolean combineUpright;
 
   // Calling reset() is forbidden because `this` isn't initialized. This can be safely suppressed
   // because reset() only assigns fields, it doesn't read any.
@@ -118,6 +119,7 @@ public final class WebvttCssStyle {
     italic = UNSPECIFIED;
     fontSizeUnit = UNSPECIFIED;
     textAlign = null;
+    combineUpright = false;
   }
 
   public void setTargetId(String targetId) {
@@ -287,6 +289,14 @@ public final class WebvttCssStyle {
     return fontSize;
   }
 
+  public void setCombineUpright(boolean enabled) {
+    this.combineUpright = enabled;
+  }
+
+  public boolean getCombineUpright() {
+    return combineUpright;
+  }
+
   private static int updateScoreForMatch(
       int currentScore, String target, @Nullable String actual, int score) {
     if (target.isEmpty() || currentScore == -1) {

library/core/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCueParser.java

@@ -37,6 +37,7 @@ import androidx.annotation.IntDef;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.text.Cue;
+import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
 import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.Log;
@@ -571,6 +572,10 @@ public final class WebvttCueParser {
         // Do nothing.
         break;
     }
+    if (style.getCombineUpright()) {
+      spannedText.setSpan(
+          new HorizontalTextInVerticalContextSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
   }
 
   /**

library/core/src/test/assets/webvtt/with_css_text_combine_upright

+WEBVTT
+
+NOTE https://developer.mozilla.org/en-US/docs/Web/CSS/text-combine-upright
+NOTE The `digits` values are ignored in CssParser and all assumed to be `all`
+
+STYLE
+::cue(.tcu-all) {
+  text-combine-upright: all;
+}
+::cue(.tcu-digits) {
+  text-combine-upright: digits 4;
+}
+
+00:00:00.000 --> 00:00:01.000 vertical:rl
+Combine <c.tcu-all>all</c> test
+
+00:03.000 --> 00:04.000 vertical:rl
+Combine <c.tcu-digits>0004</c> digits

library/core/src/test/java/com/google/android/exoplayer2/text/webvtt/WebvttDecoderTest.java

@@ -53,6 +53,8 @@ public class WebvttDecoderTest {
   private static final String WITH_TAGS_FILE = "webvtt/with_tags";
   private static final String WITH_CSS_STYLES = "webvtt/with_css_styles";
   private static final String WITH_CSS_COMPLEX_SELECTORS = "webvtt/with_css_complex_selectors";
+  private static final String WITH_CSS_TEXT_COMBINE_UPRIGHT =
+      "webvtt/with_css_text_combine_upright";
   private static final String WITH_BOM = "webvtt/with_bom";
   private static final String EMPTY_FILE = "webvtt/empty";
 
@@ -460,6 +462,20 @@ public class WebvttDecoderTest {
         .isEqualTo(Typeface.ITALIC);
   }
 
+  @Test
+  public void testWebvttWithCssTextCombineUpright() throws Exception {
+    WebvttSubtitle subtitle = getSubtitleForTestAsset(WITH_CSS_TEXT_COMBINE_UPRIGHT);
+
+    Spanned firstCueText = getUniqueSpanTextAt(subtitle, 500_000);
+    assertThat(firstCueText)
+        .hasHorizontalTextInVerticalContextSpanBetween("Combine ".length(), "Combine all".length());
+
+    Spanned secondCueText = getUniqueSpanTextAt(subtitle, 3_500_000);
+    assertThat(secondCueText)
+        .hasHorizontalTextInVerticalContextSpanBetween(
+            "Combine ".length(), "Combine 0004".length());
+  }
+
   private WebvttSubtitle getSubtitleForTestAsset(String asset)
       throws IOException, SubtitleDecoderException {
     WebvttDecoder decoder = new WebvttDecoder();

testutils/src/main/java/com/google/android/exoplayer2/testutil/truth/SpannedSubject.java

@@ -30,11 +30,13 @@ import android.text.style.UnderlineSpan;
 import androidx.annotation.CheckResult;
 import androidx.annotation.ColorInt;
 import androidx.annotation.Nullable;
+import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
 import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.common.truth.FailureMetadata;
 import com.google.common.truth.Subject;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 /** A Truth {@link Subject} for assertions on {@link Spanned} instances containing text styling. */
@@ -183,12 +185,10 @@ public final class SpannedSubject extends Subject {
     }
 
     List<UnderlineSpan> underlineSpans = findMatchingSpans(start, end, UnderlineSpan.class);
-    List<Integer> allFlags = new ArrayList<>();
-    for (UnderlineSpan span : underlineSpans) {
-      allFlags.add(actual.getSpanFlags(span));
-    }
     if (underlineSpans.size() == 1) {
-      return check("UnderlineSpan (start=%s,end=%s)", start, end).about(spanFlags()).that(allFlags);
+      return check("UnderlineSpan (start=%s,end=%s)", start, end)
+          .about(spanFlags())
+          .that(Collections.singletonList(actual.getSpanFlags(underlineSpans.get(0))));
     }
     failWithExpectedSpan(start, end, UnderlineSpan.class, actual.toString().substring(start, end));
     return ALREADY_FAILED_WITH_FLAGS;
@@ -274,6 +274,35 @@ public final class SpannedSubject extends Subject {
     return check("RubySpan (start=%s,end=%s)", start, end).about(rubySpans(actual)).that(rubySpans);
   }
 
+  /**
+   * Checks that the subject has an {@link HorizontalTextInVerticalContextSpan} from {@code start}
+   * to {@code end}.
+   *
+   * @param start The start of the expected span.
+   * @param end The end of the expected span.
+   * @return A {@link WithSpanFlags} object for optional additional assertions on the flags.
+   */
+  public WithSpanFlags hasHorizontalTextInVerticalContextSpanBetween(int start, int end) {
+    if (actual == null) {
+      failWithoutActual(simpleFact("Spanned must not be null"));
+      return ALREADY_FAILED_WITH_FLAGS;
+    }
+
+    List<HorizontalTextInVerticalContextSpan> horizontalInVerticalSpans =
+        findMatchingSpans(start, end, HorizontalTextInVerticalContextSpan.class);
+    if (horizontalInVerticalSpans.size() == 1) {
+      return check("HorizontalTextInVerticalContextSpan (start=%s,end=%s)", start, end)
+          .about(spanFlags())
+          .that(Collections.singletonList(actual.getSpanFlags(horizontalInVerticalSpans.get(0))));
+    }
+    failWithExpectedSpan(
+        start,
+        end,
+        HorizontalTextInVerticalContextSpan.class,
+        actual.toString().substring(start, end));
+    return ALREADY_FAILED_WITH_FLAGS;
+  }
+
   private <T> List<T> findMatchingSpans(int startIndex, int endIndex, Class<T> spanClazz) {
     List<T> spans = new ArrayList<>();
     for (T span : actual.getSpans(startIndex, endIndex, spanClazz)) {

testutils/src/test/java/com/google/android/exoplayer2/testutil/truth/SpannedSubjectTest.java

@@ -30,6 +30,7 @@ import android.text.style.ForegroundColorSpan;
 import android.text.style.StyleSpan;
 import android.text.style.UnderlineSpan;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
+import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
 import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.common.truth.ExpectFailure;
 import org.junit.Test;
@@ -453,6 +454,19 @@ public class SpannedSubjectTest {
         .contains(String.valueOf(Spanned.SPAN_INCLUSIVE_EXCLUSIVE));
   }
 
+  @Test
+  public void horizontalTextInVerticalContextSpan_success() {
+    SpannableString spannable = SpannableString.valueOf("vertical text with horizontal section");
+    int start = "vertical text with ".length();
+    int end = start + "horizontal".length();
+    spannable.setSpan(
+        new HorizontalTextInVerticalContextSpan(), start, end, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
+
+    assertThat(spannable)
+        .hasHorizontalTextInVerticalContextSpanBetween(start, end)
+        .withFlags(Spanned.SPAN_INCLUSIVE_EXCLUSIVE);
+  }
+
   private static AssertionError expectFailure(
       ExpectFailure.SimpleSubjectBuilderCallback<SpannedSubject, Spanned> callback) {
     return expectFailureAbout(spanned(), callback);