Parse TTML's tts:textAlign into Cue.textAlign, not an AlignmentSpan

The tts:textAlign property only applies to <p> elements, which
correspond 1:1 with ExoPlayer Cue objects, so we can use
Cue.textAlignment to store this info instead of encoding it in
the span-styled text.

This will mean that TTML subtitles used with
SubtitleView#setApplyEmbeddedStyles(false) will start respecting
the tts:textAlign properties from the source data (currently this
information is stripped when we remove all span styling). I think this
is working-as-intended, we respect alignment of other subtitle types
(e.g. WebVTT) when applyEmbeddedStyles=false. We also respect all other
'positioning' related properties in this case e.g. Cue.position and
Cue.line.

PiperOrigin-RevId: 310895499

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

@@ -380,7 +380,9 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     }
     if (resolvedStyle != null) {
       TtmlRenderUtil.applyStylesToSpan(text, start, end, resolvedStyle, parent);
-      regionOutput.setVerticalType(resolvedStyle.getVerticalType());
+      regionOutput
+          .setTextAlignment(resolvedStyle.getTextAlign())
+          .setVerticalType(resolvedStyle.getVerticalType());
     }
   }
 

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

@@ -15,12 +15,10 @@
  */
 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;
-import android.text.style.AlignmentSpan;
 import android.text.style.BackgroundColorSpan;
 import android.text.style.ForegroundColorSpan;
 import android.text.style.RelativeSizeSpan;
@@ -162,16 +160,6 @@ import java.util.Map;
         // Do nothing
         break;
     }
-
-    @Nullable Alignment textAlign = style.getTextAlign();
-    if (textAlign != null) {
-      SpanUtil.addOrReplaceSpan(
-          builder,
-          new AlignmentSpan.Standard(textAlign),
-          start,
-          end,
-          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
     if (style.getTextCombine()) {
       SpanUtil.addOrReplaceSpan(
           builder,

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_REGION_FILE = "ttml/bitmap_percentage_region.xml";
   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 TEXT_ALIGN_FILE = "ttml/text_align.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";
@@ -194,9 +195,6 @@ public final class TtmlDecoderTest {
     assertThat(firstCueText)
         .hasForegroundColorSpanBetween(0, firstCueText.length())
         .withColor(ColorParser.parseTtmlColor("lime"));
-    assertThat(firstCueText)
-        .hasAlignmentSpanBetween(0, firstCueText.length())
-        .withAlignment(Layout.Alignment.ALIGN_CENTER);
 
     Spanned secondCueText = getOnlyCueTextAtTimeUs(subtitle, 20_000_000);
     assertThat(secondCueText.toString()).isEqualTo("text 2");
@@ -210,9 +208,6 @@ public final class TtmlDecoderTest {
     assertThat(secondCueText)
         .hasForegroundColorSpanBetween(0, secondCueText.length())
         .withColor(0xFFFFFF00);
-    assertThat(secondCueText)
-        .hasAlignmentSpanBetween(0, secondCueText.length())
-        .withAlignment(Layout.Alignment.ALIGN_CENTER);
   }
 
   @Test
@@ -575,6 +570,39 @@ public final class TtmlDecoderTest {
     assertThat(cue.bitmapHeight).isEqualTo(Cue.DIMEN_UNSET);
   }
 
+  @Test
+  public void textAlign() throws IOException, SubtitleDecoderException {
+    TtmlSubtitle subtitle = getSubtitle(TEXT_ALIGN_FILE);
+
+    Cue firstCue = getOnlyCueAtTimeUs(subtitle, 10_000_000);
+    assertThat(firstCue.text.toString()).isEqualTo("Start alignment");
+    assertThat(firstCue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_NORMAL);
+
+    Cue secondCue = getOnlyCueAtTimeUs(subtitle, 20_000_000);
+    assertThat(secondCue.text.toString()).isEqualTo("Left alignment");
+    assertThat(secondCue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_NORMAL);
+
+    Cue thirdCue = getOnlyCueAtTimeUs(subtitle, 30_000_000);
+    assertThat(thirdCue.text.toString()).isEqualTo("Center alignment");
+    assertThat(thirdCue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_CENTER);
+
+    Cue fourthCue = getOnlyCueAtTimeUs(subtitle, 40_000_000);
+    assertThat(fourthCue.text.toString()).isEqualTo("Right alignment");
+    assertThat(fourthCue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_OPPOSITE);
+
+    Cue fifthCue = getOnlyCueAtTimeUs(subtitle, 50_000_000);
+    assertThat(fifthCue.text.toString()).isEqualTo("End alignment");
+    assertThat(fifthCue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_OPPOSITE);
+
+    Cue sixthCue = getOnlyCueAtTimeUs(subtitle, 60_000_000);
+    assertThat(sixthCue.text.toString()).isEqualTo("Justify alignment (unsupported)");
+    assertThat(sixthCue.textAlignment).isNull();
+
+    Cue seventhCue = getOnlyCueAtTimeUs(subtitle, 70_000_000);
+    assertThat(seventhCue.text.toString()).isEqualTo("No textAlign property");
+    assertThat(seventhCue.textAlignment).isNull();
+  }
+
   @Test
   public void verticalText() throws IOException, SubtitleDecoderException {
     TtmlSubtitle subtitle = getSubtitle(VERTICAL_TEXT_FILE);

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

@@ -14,7 +14,7 @@
                 tts:color="yellow"/>
         </styling>
     </head>
-    <body tts:textAlign="center">
+    <body>
         <div tts:fontWeight="normal"
             tts:fontStyle="normal"
             tts:fontFamily="sansSerif"

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

@@ -0,0 +1,29 @@
+<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" tts:textAlign="start">Start alignment</p>
+    </div>
+    <div>
+      <p begin="20s" end="28s" tts:textAlign="left">Left alignment</p>
+    </div>
+    <div>
+      <p begin="30s" end="38s" tts:textAlign="center">Center alignment</p>
+    </div>
+    <div>
+      <p begin="40s" end="48s" tts:textAlign="right">Right alignment</p>
+    </div>
+    <div>
+      <p begin="50s" end="58s" tts:textAlign="end">End alignment</p>
+    </div>
+    <div>
+      <p begin="60s" end="68s" tts:textAlign="justify">Justify alignment (unsupported)</p>
+    </div>
+    <div>
+      <p begin="70s" end="78s">No textAlign property</p>
+    </div>
+  </body>
+</tt>