Introduce LanguageFeatureStyle interface to mark language features

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

@@ -29,4 +29,4 @@
 // 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 {}
+public final class HorizontalTextInVerticalContextSpan implements LanguageFeatureStyle {}

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

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2021 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;
+
+/**
+ * Marker interface to mark classes that are language features.
+ */
+public interface LanguageFeatureStyle {
+}
+

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

@@ -30,7 +30,7 @@
 // extract the spans and do the layout manually.
 // TODO: Consider adding support for parenthetical text to be used when rendering doesn't support
 // rubies (e.g. HTML <rp> tag).
-public final class RubySpan {
+public final class RubySpan implements LanguageFeatureStyle {
 
   /** The ruby text, i.e. the smaller explanatory characters. */
   public final String rubyText;

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

@@ -32,7 +32,7 @@
 // NOTE: There's no Android layout support for text emphasis, so this span currently doesn't extend
 // any styling superclasses (e.g. MetricAffectingSpan). The only way to render this emphasis is to
 // extract the spans and do the layout manually.
-public final class TextEmphasisSpan {
+public final class TextEmphasisSpan implements LanguageFeatureStyle {
 
   /**
    * The possible mark shapes that can be used.

library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitleView.java

@@ -36,6 +36,7 @@
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.text.Cue;
 import com.google.android.exoplayer2.text.TextOutput;
+import com.google.android.exoplayer2.text.span.LanguageFeatureStyle;
 import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
@@ -374,47 +375,9 @@ private List<Cue> getCuesWithStylingPreferencesApplied() {
     }
     List<Cue> strippedCues = new ArrayList<>(cues.size());
     for (int i = 0; i < cues.size(); i++) {
-      strippedCues.add(removeEmbeddedStyling(cues.get(i)));
+      strippedCues.add(SubtitleViewUtils
+          .removeEmbeddedStyling(cues.get(i), applyEmbeddedStyles, applyEmbeddedFontSizes));
     }
     return strippedCues;
   }
-
-  private Cue removeEmbeddedStyling(Cue cue) {
-    @Nullable CharSequence cueText = cue.text;
-    if (!applyEmbeddedStyles) {
-      Cue.Builder strippedCue =
-          cue.buildUpon().setTextSize(Cue.DIMEN_UNSET, Cue.TYPE_UNSET).clearWindowColor();
-      if (cueText != null) {
-        // Remove all spans, regardless of type.
-        strippedCue.setText(new SpannableString(cueText.toString()));
-        if (cueText instanceof Spanned) {
-          SubtitleViewUtils
-              .preserveJapaneseLanguageFeatures((SpannableString)strippedCue.getText(),
-                  (Spanned) cueText);
-        }
-      }
-      return strippedCue.build();
-    } else if (!applyEmbeddedFontSizes) {
-      if (cueText == null) {
-        return cue;
-      }
-      Cue.Builder strippedCue = cue.buildUpon().setTextSize(Cue.DIMEN_UNSET, Cue.TYPE_UNSET);
-      if (cueText instanceof Spanned) {
-        SpannableString spannable = SpannableString.valueOf(cueText);
-        AbsoluteSizeSpan[] absSpans =
-            spannable.getSpans(0, spannable.length(), AbsoluteSizeSpan.class);
-        for (AbsoluteSizeSpan absSpan : absSpans) {
-          spannable.removeSpan(absSpan);
-        }
-        RelativeSizeSpan[] relSpans =
-            spannable.getSpans(0, spannable.length(), RelativeSizeSpan.class);
-        for (RelativeSizeSpan relSpan : relSpans) {
-          spannable.removeSpan(relSpan);
-        }
-        strippedCue.setText(spannable);
-      }
-      return strippedCue.build();
-    }
-    return cue;
-  }
 }

library/ui/src/main/java/com/google/android/exoplayer2/ui/SubtitleViewUtils.java

@@ -17,9 +17,15 @@
 package com.google.android.exoplayer2.ui;
 
 import android.text.Spannable;
+import android.text.SpannableString;
 import android.text.Spanned;
+import android.text.style.AbsoluteSizeSpan;
+import android.text.style.RelativeSizeSpan;
+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.LanguageFeatureStyle;
 import com.google.android.exoplayer2.text.span.RubySpan;
 import com.google.android.exoplayer2.text.span.SpanUtil;
 import com.google.android.exoplayer2.text.span.TextEmphasisSpan;
@@ -54,26 +60,42 @@ public static float resolveTextSize(
     }
   }
 
-  public static void preserveJapaneseLanguageFeatures(Spannable copy, Spanned original) {
-    RubySpan[] absSpans =
-        original.getSpans(0, original.length(), RubySpan.class);
-    for (RubySpan rubySpan : absSpans) {
-      SpanUtil.addOrReplaceSpan(copy, rubySpan, original.getSpanStart(rubySpan),
-          original.getSpanEnd(rubySpan), original.getSpanFlags(rubySpan));
-    }
-    TextEmphasisSpan[] textEmphasisSpans =
-        original.getSpans(0, original.length(), TextEmphasisSpan.class);
-    for (TextEmphasisSpan textEmphasisSpan : textEmphasisSpans) {
-      SpanUtil.addOrReplaceSpan(copy, textEmphasisSpan, original.getSpanStart(textEmphasisSpan),
-          original.getSpanEnd(textEmphasisSpan), original.getSpanFlags(textEmphasisSpan));
-    }
-    HorizontalTextInVerticalContextSpan[] horizontalTextInVerticalContextSpans =
-        original.getSpans(0, original.length(), HorizontalTextInVerticalContextSpan.class);
-
-    for (HorizontalTextInVerticalContextSpan span : horizontalTextInVerticalContextSpans) {
-      SpanUtil.addOrReplaceSpan(copy, span, original.getSpanStart(span),
-          original.getSpanEnd(span), original.getSpanFlags(span));
+  /**
+   * Returns a cue object with the specified styling removed
+   * @param cue - Cue object that contains all the styling information
+   * @param applyEmbeddedStyles - if true, styles embedded within the cues should be applied
+   * @param applyEmbeddedFontSizes - if true, font sizes embedded within the cues should be applied.
+   *                               Only takes effect if setApplyEmbeddedStyles is true
+   *                               See {@link SubtitleView#setApplyEmbeddedStyles}
+   * @return New cue object with the specified styling removed
+   */
+  @NonNull
+  static Cue removeEmbeddedStyling(@NonNull Cue cue, boolean applyEmbeddedStyles,
+      boolean applyEmbeddedFontSizes) {
+    @Nullable CharSequence cueText = cue.text;
+    if (cueText != null && (!applyEmbeddedStyles || !applyEmbeddedFontSizes)) {
+      Cue.Builder strippedCue = cue.buildUpon().setTextSize(Cue.DIMEN_UNSET, Cue.TYPE_UNSET);
+      if (!applyEmbeddedStyles) {
+        strippedCue.clearWindowColor();
+      }
+      if (cueText instanceof Spanned) {
+        SpannableString spannable = SpannableString.valueOf(cueText);
+        Object[] spans = spannable.getSpans(0, spannable.length(), Object.class);
+        for (Object span : spans) {
+          if (span instanceof LanguageFeatureStyle) {
+            continue;
+          }
+          // applyEmbeddedFontSizes should only be applied if applyEmbeddedStyles is true
+          if (!applyEmbeddedStyles || span instanceof AbsoluteSizeSpan
+              || span instanceof RelativeSizeSpan) {
+            spannable.removeSpan(span);
+          }
+        }
+        strippedCue.setText(spannable);
+      }
+      return strippedCue.build();
     }
+    return cue;
   }
 
   private SubtitleViewUtils() {}