Add support for SSA (V4+) PrimaryColour style

demos/main/src/main/assets/media.exolist.json

@@ -506,6 +506,13 @@
         "subtitle_mime_type": "text/x-ssa",
         "subtitle_language": "en"
       },
+      {
+        "name": "SubStation Alpha colors",
+        "uri": "https://storage.googleapis.com/exoplayer-test-media-1/gen-3/screens/dash-vod-single-segment/video-avc-baseline-480.mp4",
+        "subtitle_uri": "https://drive.google.com/uc?export=download&id=13EdW4Qru-vQerUlwS_Ht5Cely_Tn0tQe",
+        "subtitle_mime_type": "text/x-ssa",
+        "subtitle_language": "en"
+      },
       {
         "name": "MPEG-4 Timed Text",
         "uri": "https://storage.googleapis.com/exoplayer-test-media-1/mp4/dizzy-with-tx3g.mp4"

library/core/src/main/java/com/google/android/exoplayer2/text/ssa/SsaDecoder.java

@@ -19,6 +19,8 @@ import static com.google.android.exoplayer2.text.Cue.LINE_TYPE_FRACTION;
 import static com.google.android.exoplayer2.util.Util.castNonNull;
 
 import android.text.Layout;
+import android.text.SpannableString;
+import android.text.style.ForegroundColorSpan;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.text.Cue;
@@ -301,8 +303,17 @@ public final class SsaDecoder extends SimpleSubtitleDecoder {
       SsaStyle.Overrides styleOverrides,
       float screenWidth,
       float screenHeight) {
-    Cue.Builder cue = new Cue.Builder().setText(text);
+    SpannableString spannableText = new SpannableString(text);
+    Cue.Builder cue = new Cue.Builder().setText(spannableText);
 
+    // Apply primary color.
+    if (style != null) {
+      if (style.primaryColor != SsaStyle.SSA_COLOR_UNKNOWN) {
+        spannableText.setSpan(new ForegroundColorSpan(style.primaryColor),
+            0, spannableText.length(), SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);
+      }
+    }
+    // Apply alignment.
     @SsaStyle.SsaAlignment int alignment;
     if (styleOverrides.alignment != SsaStyle.SSA_ALIGNMENT_UNKNOWN) {
       alignment = styleOverrides.alignment;

library/core/src/main/java/com/google/android/exoplayer2/text/ssa/SsaStyle.java

@@ -21,10 +21,12 @@ import static java.lang.annotation.RetentionPolicy.SOURCE;
 
 import android.graphics.PointF;
 import android.text.TextUtils;
+import androidx.annotation.ColorInt;
 import androidx.annotation.IntDef;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.ColorParser;
 import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.Util;
 import java.lang.annotation.Documented;
@@ -83,12 +85,16 @@ import java.util.regex.Pattern;
   public static final int SSA_ALIGNMENT_TOP_CENTER = 8;
   public static final int SSA_ALIGNMENT_TOP_RIGHT = 9;
 
+  public static final int SSA_COLOR_UNKNOWN = -1;
+
   public final String name;
   @SsaAlignment public final int alignment;
+  @ColorInt public int primaryColor;
 
-  private SsaStyle(String name, @SsaAlignment int alignment) {
+  private SsaStyle(String name, @SsaAlignment int alignment, @ColorInt int primaryColor) {
     this.name = name;
     this.alignment = alignment;
+    this.primaryColor = primaryColor;
   }
 
   @Nullable
@@ -105,7 +111,9 @@ import java.util.regex.Pattern;
     }
     try {
       return new SsaStyle(
-          styleValues[format.nameIndex].trim(), parseAlignment(styleValues[format.alignmentIndex]));
+          styleValues[format.nameIndex].trim(),
+          parseAlignment(styleValues[format.alignmentIndex]),
+          parsePrimaryColor(styleValues[format.primaryColorIndex]));
     } catch (RuntimeException e) {
       Log.w(TAG, "Skipping malformed 'Style:' line: '" + styleLine + "'", e);
       return null;
@@ -144,6 +152,16 @@ import java.util.regex.Pattern;
     }
   }
 
+  @ColorInt
+  private static int parsePrimaryColor(String primaryColorStr) {
+    try {
+      return ColorParser.parseSsaColor(primaryColorStr);
+    } catch (IllegalArgumentException ex) {
+      Log.w(TAG, "Failed parsing color value: " + primaryColorStr);
+    }
+    return SSA_COLOR_UNKNOWN;
+  }
+
   /**
    * Represents a {@code Format:} line from the {@code [V4+ Styles]} section
    *
@@ -154,11 +172,13 @@ import java.util.regex.Pattern;
 
     public final int nameIndex;
     public final int alignmentIndex;
+    public final int primaryColorIndex;
     public final int length;
 
-    private Format(int nameIndex, int alignmentIndex, int length) {
+    private Format(int nameIndex, int alignmentIndex, int primaryColorIndex, int length) {
       this.nameIndex = nameIndex;
       this.alignmentIndex = alignmentIndex;
+      this.primaryColorIndex = primaryColorIndex;
       this.length = length;
     }
 
@@ -171,6 +191,7 @@ import java.util.regex.Pattern;
     public static Format fromFormatLine(String styleFormatLine) {
       int nameIndex = C.INDEX_UNSET;
       int alignmentIndex = C.INDEX_UNSET;
+      int primaryColorIndex = C.INDEX_UNSET;
       String[] keys =
           TextUtils.split(styleFormatLine.substring(SsaDecoder.FORMAT_LINE_PREFIX.length()), ",");
       for (int i = 0; i < keys.length; i++) {
@@ -181,9 +202,14 @@ import java.util.regex.Pattern;
           case "alignment":
             alignmentIndex = i;
             break;
+          case "primarycolour":
+            primaryColorIndex = i;
+            break;
         }
       }
-      return nameIndex != C.INDEX_UNSET ? new Format(nameIndex, alignmentIndex, keys.length) : null;
+      return nameIndex != C.INDEX_UNSET
+          ? new Format(nameIndex, alignmentIndex, primaryColorIndex, keys.length)
+          : null;
     }
   }
 

library/core/src/main/java/com/google/android/exoplayer2/util/ColorParser.java

@@ -67,6 +67,27 @@ public final class ColorParser {
     return parseColorInternal(colorExpression, true);
   }
 
+  /**
+   * Parses a SSA V4+ color expression.
+   *
+   * @param colorExpression The color expression.
+   * @return The parsed ARGB color.
+   */
+  @ColorInt
+  public static int parseSsaColor(String colorExpression) {
+    // SSA V4+ color format is &HAABBGGRR.
+    if (colorExpression.length() != 10 || !"&H".equals(colorExpression.substring(0, 2))) {
+      throw new IllegalArgumentException();
+    }
+    // Convert &HAABBGGRR to #RRGGBBAA.
+    String rgba = new StringBuilder()
+        .append(colorExpression.substring(2))
+        .append("#")
+        .reverse()
+        .toString();
+    return parseColorInternal(rgba, true);
+  }
+
   @ColorInt
   private static int parseColorInternal(String colorExpression, boolean alphaHasFloatFormat) {
     Assertions.checkArgument(!TextUtils.isEmpty(colorExpression));

library/core/src/test/java/com/google/android/exoplayer2/util/ColorParserTest.java

@@ -18,8 +18,10 @@ package com.google.android.exoplayer2.util;
 import static android.graphics.Color.BLACK;
 import static android.graphics.Color.RED;
 import static android.graphics.Color.WHITE;
+import static android.graphics.Color.YELLOW;
 import static android.graphics.Color.argb;
 import static android.graphics.Color.parseColor;
+import static com.google.android.exoplayer2.util.ColorParser.parseSsaColor;
 import static com.google.android.exoplayer2.util.ColorParser.parseTtmlColor;
 import static com.google.common.truth.Truth.assertThat;
 
@@ -64,6 +66,9 @@ public final class ColorParserTest {
     // Hex colors in ColorParser are RGBA, where-as {@link Color#parseColor} takes ARGB.
     assertThat(parseTtmlColor("#FFFFFF00")).isEqualTo(parseColor("#00FFFFFF"));
     assertThat(parseTtmlColor("#12345678")).isEqualTo(parseColor("#78123456"));
+    // SSA colors are in &HAABBGGRR format.
+    assertThat(parseSsaColor("&HFF0000FF")).isEqualTo(RED);
+    assertThat(parseSsaColor("&HFF00FFFF")).isEqualTo(YELLOW);
   }
 
   @Test