CuePainter fixes for caption styling.

- Don't allow "nothing has changed" optimization in the case
  that only styling has changed (TextUtils.equals will return
  true in this case, but we shouldn't optimize).
- Add functionality to suppress embedded styling; seems useful
  to have.
- Added "this." for clarity.

library/src/main/java/com/google/android/exoplayer/text/CuePainter.java

@@ -71,6 +71,7 @@ import android.util.Log;
   private CharSequence cueText;
   private int cuePosition;
   private Alignment cueAlignment;
+  private boolean applyEmbeddedStyles;
   private int foregroundColor;
   private int backgroundColor;
   private int windowColor;
@@ -121,6 +122,7 @@ import android.util.Log;
    * which the same parameters are passed.
    *
    * @param cue The cue to draw.
+   * @param applyEmbeddedStyles Whether styling embedded within the cue should be applied.
    * @param style The style to use when drawing the cue text.
    * @param fontScale The font scale.
    * @param bottomPaddingFraction The bottom padding fraction to apply when {@link Cue#line} is
@@ -131,48 +133,55 @@ import android.util.Log;
    * @param cueBoxRight The right position of the enclosing cue box.
    * @param cueBoxBottom The bottom position of the enclosing cue box.
    */
-  public void draw(Cue cue, CaptionStyleCompat style, float fontScale, float bottomPaddingFraction,
-      Canvas canvas, int cueBoxLeft, int cueBoxTop, int cueBoxRight, int cueBoxBottom) {
-    if (TextUtils.isEmpty(cue.text)) {
+  public void draw(Cue cue, boolean applyEmbeddedStyles, CaptionStyleCompat style, float fontScale,
+      float bottomPaddingFraction, Canvas canvas, int cueBoxLeft, int cueBoxTop, int cueBoxRight,
+      int cueBoxBottom) {
+    CharSequence cueText = cue.text;
+    if (TextUtils.isEmpty(cueText)) {
       // Nothing to draw.
       return;
     }
-
-    if (TextUtils.equals(cueText, cue.text)
-        && cuePosition == cue.position
-        && Util.areEqual(cueAlignment, cue.alignment)
-        && foregroundColor == style.foregroundColor
-        && backgroundColor == style.backgroundColor
-        && windowColor == style.windowColor
-        && edgeType == style.edgeType
-        && edgeColor == style.edgeColor
-        && Util.areEqual(textPaint.getTypeface(), style.typeface)
+    if (!applyEmbeddedStyles) {
+      // Strip out any embedded styling.
+      cueText = cueText.toString();
+    }
+    if (areCharSequencesEqual(this.cueText, cueText)
+        && this.cuePosition == cue.position
+        && Util.areEqual(this.cueAlignment, cue.alignment)
+        && this.applyEmbeddedStyles == applyEmbeddedStyles
+        && this.foregroundColor == style.foregroundColor
+        && this.backgroundColor == style.backgroundColor
+        && this.windowColor == style.windowColor
+        && this.edgeType == style.edgeType
+        && this.edgeColor == style.edgeColor
+        && Util.areEqual(this.textPaint.getTypeface(), style.typeface)
         && this.fontScale == fontScale
         && this.bottomPaddingFraction == bottomPaddingFraction
-        && parentLeft == cueBoxLeft
-        && parentTop == cueBoxTop
-        && parentRight == cueBoxRight
-        && parentBottom == cueBoxBottom) {
+        && this.parentLeft == cueBoxLeft
+        && this.parentTop == cueBoxTop
+        && this.parentRight == cueBoxRight
+        && this.parentBottom == cueBoxBottom) {
       // We can use the cached layout.
       drawLayout(canvas);
       return;
     }
 
-    cueText = cue.text;
-    cuePosition = cue.position;
-    cueAlignment = cue.alignment;
-    foregroundColor = style.foregroundColor;
-    backgroundColor = style.backgroundColor;
-    windowColor = style.windowColor;
-    edgeType = style.edgeType;
-    edgeColor = style.edgeColor;
-    textPaint.setTypeface(style.typeface);
+    this.cueText = cueText;
+    this.cuePosition = cue.position;
+    this.cueAlignment = cue.alignment;
+    this.applyEmbeddedStyles = applyEmbeddedStyles;
+    this.foregroundColor = style.foregroundColor;
+    this.backgroundColor = style.backgroundColor;
+    this.windowColor = style.windowColor;
+    this.edgeType = style.edgeType;
+    this.edgeColor = style.edgeColor;
+    this.textPaint.setTypeface(style.typeface);
     this.fontScale = fontScale;
     this.bottomPaddingFraction = bottomPaddingFraction;
-    parentLeft = cueBoxLeft;
-    parentTop = cueBoxTop;
-    parentRight = cueBoxRight;
-    parentBottom = cueBoxBottom;
+    this.parentLeft = cueBoxLeft;
+    this.parentTop = cueBoxTop;
+    this.parentRight = cueBoxRight;
+    this.parentBottom = cueBoxBottom;
 
     int parentWidth = parentRight - parentLeft;
     int parentHeight = parentBottom - parentTop;
@@ -297,4 +306,15 @@ import android.util.Log;
     canvas.restoreToCount(saveCount);
   }
 
+  /**
+   * This method is used instead of {@link TextUtils#equals(CharSequence, CharSequence)} because the
+   * latter only checks the text of each sequence, and does not check for equality of styling that
+   * may be embedded within the {@link CharSequence}s.
+   */
+  private static boolean areCharSequencesEqual(CharSequence first, CharSequence second) {
+    // Some CharSequence implementations don't perform a cheap referential equality check in their
+    // equals methods, so we perform one explicitly here.
+    return first == second || (first != null && first.equals(second));
+  }
+
 }

library/src/main/java/com/google/android/exoplayer/text/SubtitleLayout.java

@@ -38,6 +38,7 @@ public final class SubtitleLayout extends View {
 
   private List<Cue> cues;
   private float fontScale;
+  private boolean applyEmbeddedStyles;
   private CaptionStyleCompat style;
   private float bottomPaddingFraction;
 
@@ -49,6 +50,7 @@ public final class SubtitleLayout extends View {
     super(context, attrs);
     painters = new ArrayList<>();
     fontScale = 1;
+    applyEmbeddedStyles = true;
     style = CaptionStyleCompat.DEFAULT;
     bottomPaddingFraction = DEFAULT_BOTTOM_PADDING_FRACTION;
   }
@@ -87,7 +89,21 @@ public final class SubtitleLayout extends View {
   }
 
   /**
-   * Configures the view according to the given style.
+   * Sets whether styling embedded within the cues should be applied. Enabled by default.
+   *
+   * @param applyEmbeddedStyles Whether styling embedded within the cues should be applied.
+   */
+  public void setApplyEmbeddedStyles(boolean applyEmbeddedStyles) {
+    if (this.applyEmbeddedStyles == applyEmbeddedStyles) {
+      return;
+    }
+    this.applyEmbeddedStyles = applyEmbeddedStyles;
+    // Invalidate to trigger drawing.
+    invalidate();
+  }
+
+  /**
+   * Sets the caption style.
    *
    * @param style A style for the view.
    */
@@ -119,8 +135,8 @@ public final class SubtitleLayout extends View {
   public void dispatchDraw(Canvas canvas) {
     int cueCount = (cues == null) ? 0 : cues.size();
     for (int i = 0; i < cueCount; i++) {
-      painters.get(i).draw(cues.get(i), style, fontScale, bottomPaddingFraction, canvas, getLeft(),
-          getTop(), getRight(), getBottom());
+      painters.get(i).draw(cues.get(i), applyEmbeddedStyles, style, fontScale,
+          bottomPaddingFraction, canvas, getLeft(), getTop(), getRight(), getBottom());
     }
   }