Add fall-back behaviour for vertical cues if rendering isn't supported

PiperOrigin-RevId: 308854072

RELEASENOTES.md

@@ -107,6 +107,8 @@
     *   Implement timing-out of stuck CEA-608 captions (as permitted by
         ANSI/CTA-608-E R-2014 Annex C.9) and set the default timeout to 16
         seconds ([#7181](https://github.com/google/ExoPlayer/issues/7181)).
+    *   Add special-case positioning behaviour for vertical cues being rendered
+        horizontally.
 *   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/Cue.java

@@ -460,6 +460,11 @@ public final class Cue {
     this.verticalType = verticalType;
   }
 
+  /** Returns a new {@link Cue.Builder} initialized with the same values as this Cue. */
+  public Builder buildUpon() {
+    return new Cue.Builder(this);
+  }
+
   /** A builder for {@link Cue} objects. */
   public static final class Builder {
     @Nullable private CharSequence text;
@@ -496,6 +501,24 @@ public final class Cue {
       verticalType = TYPE_UNSET;
     }
 
+    private Builder(Cue cue) {
+      text = cue.text;
+      bitmap = cue.bitmap;
+      textAlignment = cue.textAlignment;
+      line = cue.line;
+      lineType = cue.lineType;
+      lineAnchor = cue.lineAnchor;
+      position = cue.position;
+      positionAnchor = cue.positionAnchor;
+      textSizeType = cue.textSizeType;
+      textSize = cue.textSize;
+      size = cue.size;
+      bitmapHeight = cue.bitmapHeight;
+      windowColorSet = cue.windowColorSet;
+      windowColor = cue.windowColor;
+      verticalType = cue.verticalType;
+    }
+
     /**
      * Sets the cue text.
      *

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

@@ -22,6 +22,7 @@ import static org.junit.Assert.assertThrows;
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.text.Layout;
+import android.text.SpannedString;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -31,10 +32,10 @@ import org.junit.runner.RunWith;
 public class CueTest {
 
   @Test
-  public void buildSucceeds() {
+  public void buildAndBuildUponWorkAsExpected() {
     Cue cue =
         new Cue.Builder()
-            .setText("text")
+            .setText(SpannedString.valueOf("text"))
             .setTextAlignment(Layout.Alignment.ALIGN_CENTER)
             .setLine(5, Cue.LINE_TYPE_NUMBER)
             .setLineAnchor(Cue.ANCHOR_TYPE_END)
@@ -46,7 +47,9 @@ public class CueTest {
             .setVerticalType(Cue.VERTICAL_TYPE_RL)
             .build();
 
-    assertThat(cue.text).isEqualTo("text");
+    Cue modifiedCue = cue.buildUpon().build();
+
+    assertThat(cue.text.toString()).isEqualTo("text");
     assertThat(cue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_CENTER);
     assertThat(cue.line).isEqualTo(5);
     assertThat(cue.lineType).isEqualTo(Cue.LINE_TYPE_NUMBER);
@@ -58,6 +61,19 @@ public class CueTest {
     assertThat(cue.windowColor).isEqualTo(Color.CYAN);
     assertThat(cue.windowColorSet).isTrue();
     assertThat(cue.verticalType).isEqualTo(Cue.VERTICAL_TYPE_RL);
+
+    assertThat(modifiedCue.text).isSameInstanceAs(cue.text);
+    assertThat(modifiedCue.textAlignment).isEqualTo(cue.textAlignment);
+    assertThat(modifiedCue.line).isEqualTo(cue.line);
+    assertThat(modifiedCue.lineType).isEqualTo(cue.lineType);
+    assertThat(modifiedCue.position).isEqualTo(cue.position);
+    assertThat(modifiedCue.positionAnchor).isEqualTo(cue.positionAnchor);
+    assertThat(modifiedCue.textSize).isEqualTo(cue.textSize);
+    assertThat(modifiedCue.textSizeType).isEqualTo(cue.textSizeType);
+    assertThat(modifiedCue.size).isEqualTo(cue.size);
+    assertThat(modifiedCue.windowColor).isEqualTo(cue.windowColor);
+    assertThat(modifiedCue.windowColorSet).isEqualTo(cue.windowColorSet);
+    assertThat(modifiedCue.verticalType).isEqualTo(cue.verticalType);
   }
 
   @Test
@@ -71,7 +87,7 @@ public class CueTest {
         RuntimeException.class,
         () ->
             new Cue.Builder()
-                .setText("foo")
+                .setText(SpannedString.valueOf("text"))
                 .setBitmap(Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888))
                 .build());
   }

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

@@ -154,6 +154,9 @@ import java.util.List;
     int cueCount = cues.size();
     for (int i = 0; i < cueCount; i++) {
       Cue cue = cues.get(i);
+      if (cue.verticalType != Cue.TYPE_UNSET) {
+        cue = repositionVerticalCue(cue);
+      }
       float cueTextSizePx =
           SubtitleViewUtils.resolveCueTextSize(cue, rawViewHeight, viewHeightMinusPadding);
       SubtitlePainter painter = painters.get(i);
@@ -172,4 +175,46 @@ import java.util.List;
           bottom);
     }
   }
+
+  /**
+   * Reposition a vertical cue for horizontal display.
+   *
+   * <p>This class doesn't support rendering vertical text, but if we naively interpret vertical
+   * {@link Cue#position} and{@link Cue#line} values for horizontal display then the cues will often
+   * be displayed in unexpected positions. For example, the 'default' position for vertical-rl
+   * subtitles is the right-hand edge of the viewport, so cues that would appear vertically in this
+   * position should appear horizontally at the bottom of the viewport (generally the default
+   * position). Similarly left-edge vertical-rl cues should be shown at the top of a horizontal
+   * viewport.
+   *
+   * <p>There isn't a meaningful way to transform {@link Cue#position} and related values (e.g.
+   * alignment), so we clear these and allow {@link SubtitlePainter} to do the default behaviour of
+   * centering the cue.
+   */
+  private static Cue repositionVerticalCue(Cue cue) {
+    Cue.Builder cueBuilder =
+        cue.buildUpon()
+            .setPosition(Cue.DIMEN_UNSET)
+            .setPositionAnchor(Cue.TYPE_UNSET)
+            .setTextAlignment(null);
+
+    if (cue.lineType == Cue.LINE_TYPE_FRACTION) {
+      cueBuilder.setLine(1.0f - cue.line, Cue.LINE_TYPE_FRACTION);
+    } else {
+      cueBuilder.setLine(-cue.line - 1f, Cue.LINE_TYPE_NUMBER);
+    }
+    switch (cue.lineAnchor) {
+      case Cue.ANCHOR_TYPE_END:
+        cueBuilder.setLineAnchor(Cue.ANCHOR_TYPE_START);
+        break;
+      case Cue.ANCHOR_TYPE_START:
+        cueBuilder.setLineAnchor(Cue.ANCHOR_TYPE_END);
+        break;
+      case Cue.ANCHOR_TYPE_MIDDLE:
+      case Cue.TYPE_UNSET:
+      default:
+        // Fall through
+    }
+    return cueBuilder.build();
+  }
 }