From b6f15a17e0f0a260f6e3a81040d227142da4e191 Mon Sep 17 00:00:00 2001
From: Oliver Woodman <olly@google.com>
Date: Tue, 15 Sep 2015 13:44:52 +0100
Subject: [PATCH] TTML improvements.

- do not denormalize styles at parsing time but only put normalized style info
into TtmlNode tree. Resolve styles on demand when Cues are requested for a
given timeUs.
- create TtmlRenderUtil to have static render functions separate
- added unit test for TtmlRenderUtil
- adjusted testing strategy for unit test to check resolved style on Spannables after rendering
---
 .../assets/ttml/chain_multiple_styles.xml     |   3 +
 .../assets/ttml/inherit_multiple_styles.xml   |  10 +-
 .../assets/ttml/instance_creation.xml         |  24 --
 .../ttml/non_inheritable_properties.xml       |  19 --
 .../exoplayer/text/ttml/TtmlParserTest.java   | 263 +++++++-----------
 .../text/ttml/TtmlRenderUtilTest.java         | 111 ++++++++
 .../android/exoplayer/text/ttml/TtmlNode.java | 122 +++-----
 .../exoplayer/text/ttml/TtmlParser.java       |  55 +---
 .../exoplayer/text/ttml/TtmlRenderUtil.java   | 143 ++++++++++
 .../exoplayer/text/ttml/TtmlSubtitle.java     |  12 +-
 10 files changed, 421 insertions(+), 341 deletions(-)
 delete mode 100644 library/src/androidTest/assets/ttml/instance_creation.xml
 delete mode 100644 library/src/androidTest/assets/ttml/non_inheritable_properties.xml
 create mode 100644 library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtilTest.java
 create mode 100644 library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtil.java
diff --git a/library/src/androidTest/assets/ttml/chain_multiple_styles.xml b/library/src/androidTest/assets/ttml/chain_multiple_styles.xml
index d4de3c8ef9..7bcce6527d 100644
--- a/library/src/androidTest/assets/ttml/chain_multiple_styles.xml
+++ b/library/src/androidTest/assets/ttml/chain_multiple_styles.xml
@@ -18,6 +18,9 @@
       <style style="s0 s1" id="s2"
         tts:fontFamily="serif"
         tts:backgroundColor="red" />
+      <style style="s1 s0" id="s3"
+        tts:fontFamily="serif"
+        tts:backgroundColor="red" />
     </styling>
   </head>
   <body>
diff --git a/library/src/androidTest/assets/ttml/inherit_multiple_styles.xml b/library/src/androidTest/assets/ttml/inherit_multiple_styles.xml
index 3320db70b2..3ee089c3ff 100644
--- a/library/src/androidTest/assets/ttml/inherit_multiple_styles.xml
+++ b/library/src/androidTest/assets/ttml/inherit_multiple_styles.xml
@@ -26,20 +26,20 @@
       <p style="s0 s1" begin="10s" end="18s" tts:color="yellow">text 1</p>
     </div>
     <div>
-      <p style="s0 s1" begin="20s" end="28s">text 1</p>
+      <p style="s0 s1" begin="20s" end="28s">text 2</p>
     </div>
     <div tts:color="yellow" tts:textDecoration="underline" tts:fontStyle="italic" tts:fontFamily="sansSerifInline">
-      <p style="s2                           s3" begin="30s" end="38s">text 1</p>
+      <p style="s2                           s3" begin="30s" end="38s">text 2.5</p>
     </div>
     <div>
       <!-- empty style attribute -->
-      <p style=" " begin="40s" end="48s">text 1</p>
+      <p style=" " begin="40s" end="48s">text 3</p>
     </div>
     <div>
-      <p style="not_existing" begin="50s" end="58s">text 1</p>
+      <p style="not_existing" begin="50s" end="58s">text 4</p>
     </div>
     <div>
-      <p style="not_existing s2" begin="60s" end="68s">text 1</p>
+      <p style="not_existing s2" begin="60s" end="68s">text 5</p>
     </div>
   </body>
 </tt>
diff --git a/library/src/androidTest/assets/ttml/instance_creation.xml b/library/src/androidTest/assets/ttml/instance_creation.xml
deleted file mode 100644
index 0916002e52..0000000000
--- a/library/src/androidTest/assets/ttml/instance_creation.xml
+++ /dev/null
@@ -1,24 +0,0 @@
-<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">
-  <head>
-    <styling>
-      <style id="s0"
-        tts:color="blue"/>
-      <style id="s1"
-        tts:backgroundColor="red"/>
-    </styling>
-  </head>
-  <body style="s0">
-    <div>
-      <p style="s0" begin="10s" end="18s">text 1</p>
-    </div>
-    <div>
-      <p style="s0" begin="20s" end="28s">text <span style="s0">2</span></p>
-    </div>
-    <div>
-      <p style="s1" begin="20s" end="28s">text <span style="s1">3</span></p>
-    </div>
-  </body>
-</tt>
diff --git a/library/src/androidTest/assets/ttml/non_inheritable_properties.xml b/library/src/androidTest/assets/ttml/non_inheritable_properties.xml
deleted file mode 100644
index b16e63e674..0000000000
--- a/library/src/androidTest/assets/ttml/non_inheritable_properties.xml
+++ /dev/null
@@ -1,19 +0,0 @@
-<tt xmlns="http://www.w3.org/ns/ttml"
-    xmlns="http://www.w3.org/2006/10/ttaf1"
-    xmlns:ttp="http://www.w3.org/2006/10/ttaf1#parameter"
-    xmlns:tts="http://www.w3.org/2006/10/ttaf1#style"
-    xmlns:ttm="http://www.w3.org/2006/10/ttaf1#metadata">
-  <body>
-    <div>
-      <p begin="10s" end="18s"
-        tts:fontWeight="bold"
-        tts:fontStyle="italic"
-        tts:fontFamily="serif"
-        tts:textDecoration="underline"
-        tts:backgroundColor="blue"
-        tts:color="yellow">
-        <span>text 1</span>
-      </p>
-    </div>
-  </body>
-</tt>
diff --git a/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlParserTest.java b/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlParserTest.java
index 804dca8b15..9d5d953977 100644
--- a/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlParserTest.java
+++ b/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlParserTest.java
@@ -15,12 +15,24 @@
  */
 package com.google.android.exoplayer.text.ttml;
 
+import com.google.android.exoplayer.text.Cue;
+
 import android.graphics.Color;
 import android.test.InstrumentationTestCase;
 import android.text.Layout;
+import android.text.SpannableStringBuilder;
+import android.text.style.AlignmentSpan;
+import android.text.style.BackgroundColorSpan;
+import android.text.style.ForegroundColorSpan;
+import android.text.style.StrikethroughSpan;
+import android.text.style.StyleSpan;
+import android.text.style.TypefaceSpan;
+import android.text.style.UnderlineSpan;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.List;
+import java.util.Map;
 
 /**
  * Unit test for {@link TtmlParser}.
@@ -35,16 +47,12 @@ public final class TtmlParserTest extends InstrumentationTestCase {
       "ttml/inherit_and_override_style.xml";
   private static final String INHERIT_GLOBAL_AND_PARENT_TTML_FILE =
       "ttml/inherit_global_and_parent.xml";
-  private static final String NON_INHERTABLE_PROPERTIES_TTML_FILE =
-      "ttml/non_inheritable_properties.xml";
   private static final String INHERIT_MULTIPLE_STYLES_TTML_FILE =
       "ttml/inherit_multiple_styles.xml";
   private static final String CHAIN_MULTIPLE_STYLES_TTML_FILE =
       "ttml/chain_multiple_styles.xml";
   private static final String NO_UNDERLINE_LINETHROUGH_TTML_FILE =
       "ttml/no_underline_linethrough.xml";
-  private static final String INSTANCE_CREATION_TTML_FILE =
-      "ttml/instance_creation.xml";
   private static final String NAMESPACE_CONFUSION_TTML_FILE =
       "ttml/namespace_confusion.xml";
   private static final String NAMESPACE_NOT_DECLARED_TTML_FILE =
@@ -67,143 +75,53 @@ public final class TtmlParserTest extends InstrumentationTestCase {
   }
 
   public void testInheritInlineAttributes() throws IOException {
-
     TtmlSubtitle subtitle = getSubtitle(INLINE_ATTRIBUTES_TTML_FILE);
     assertEquals(4, subtitle.getEventTimeCount());
-
-    TtmlNode root = subtitle.getRoot();
-    // inherite inline attributes
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode secondDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 1);
-    TtmlStyle secondPStyle = queryChildrenForTag(secondDiv, TtmlNode.TAG_P, 0).style;
-    assertEquals(Color.parseColor("lime"), secondPStyle.getColor());
-    assertFalse(secondPStyle.hasBackgroundColorSpecified());
-    assertEquals(0, secondPStyle.getBackgroundColor());
-    assertEquals("sansSerif", secondPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_ITALIC, secondPStyle.getStyle());
-    assertTrue(secondPStyle.isLinethrough());
+    assertSpans(subtitle, 20, "text 2", "sansSerif", TtmlStyle.STYLE_ITALIC,
+        Color.CYAN, Color.parseColor("lime"), false, true, null);
   }
 
   public void testInheritGlobalStyle() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_STYLE_TTML_FILE);
     assertEquals(2, subtitle.getEventTimeCount());
-
-    TtmlNode root = subtitle.getRoot();
-
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode firstDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
-    TtmlStyle firstPStyle = queryChildrenForTag(firstDiv, TtmlNode.TAG_P, 0).style;
-    assertEquals(Color.parseColor("yellow"), firstPStyle.getColor());
-    assertEquals(Color.parseColor("blue"), firstPStyle.getBackgroundColor());
-    assertEquals("serif", firstPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, firstPStyle.getStyle());
-    assertTrue(firstPStyle.isUnderline());
+    assertSpans(subtitle, 10, "text 1", "serif", TtmlStyle.STYLE_BOLD_ITALIC,
+        Color.BLUE, Color.YELLOW, true, false, null);
   }
 
   public void testInheritGlobalStyleOverriddenByInlineAttributes() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_STYLE_OVERRIDE_TTML_FILE);
     assertEquals(4, subtitle.getEventTimeCount());
 
-    TtmlNode root = subtitle.getRoot();
-
-    // first pNode inherits global style
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode firstDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
-    TtmlStyle firstPStyle = queryChildrenForTag(firstDiv, TtmlNode.TAG_P, 0).style;
-    assertEquals(Color.parseColor("yellow"), firstPStyle.getColor());
-    assertEquals(Color.parseColor("blue"), firstPStyle.getBackgroundColor());
-    assertEquals("serif", firstPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, firstPStyle.getStyle());
-    assertTrue(firstPStyle.isUnderline());
-
-    // second pNode inherits global style and overrides with attribute
-    TtmlNode secondDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 1);
-    TtmlStyle secondPStyle = queryChildrenForTag(secondDiv, TtmlNode.TAG_P, 0).style;
-    assertEquals(Color.parseColor("yellow"), secondPStyle.getColor());
-    assertEquals(Color.parseColor("red"), secondPStyle.getBackgroundColor());
-    assertEquals("sansSerif", secondPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_ITALIC, secondPStyle.getStyle());
-    assertTrue(secondPStyle.isUnderline());
+    assertSpans(subtitle, 10, "text 1", "serif", TtmlStyle.STYLE_BOLD_ITALIC, Color.BLUE,
+        Color.YELLOW, true, false, null);
+    assertSpans(subtitle, 20, "text 2", "sansSerif", TtmlStyle.STYLE_ITALIC, Color.RED,
+        Color.YELLOW, true, false, null);
   }
 
   public void testInheritGlobalAndParent() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_GLOBAL_AND_PARENT_TTML_FILE);
     assertEquals(4, subtitle.getEventTimeCount());
 
-    TtmlNode root = subtitle.getRoot();
-
-    // first pNode inherits parent style
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode firstDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
-    TtmlStyle firstPStyle = queryChildrenForTag(firstDiv, TtmlNode.TAG_P, 0).style;
-
-    assertFalse(firstPStyle.hasBackgroundColorSpecified());
-    assertEquals(0, firstPStyle.getBackgroundColor());
-
-    assertEquals(Color.parseColor("lime"), firstPStyle.getColor());
-    assertEquals("sansSerif", firstPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_NORMAL, firstPStyle.getStyle());
-    assertTrue(firstPStyle.isLinethrough());
-
-    // second pNode inherits parent style and overrides with global style
-    TtmlNode secondDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 1);
-    TtmlStyle secondPStyle = queryChildrenForTag(secondDiv, TtmlNode.TAG_P, 0).style;
-    // attributes overridden by global style
-    assertEquals(Color.parseColor("blue"), secondPStyle.getBackgroundColor());
-    assertEquals(Color.parseColor("yellow"), secondPStyle.getColor());
-    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, secondPStyle.getStyle());
-    assertEquals("serif", secondPStyle.getFontFamily());
-    assertTrue(secondPStyle.isUnderline());
-    assertEquals(Layout.Alignment.ALIGN_CENTER, secondPStyle.getTextAlign());
-  }
-
-  public void testNonInheritablePropertiesAreNotInherited() throws IOException {
-    TtmlSubtitle subtitle = getSubtitle(NON_INHERTABLE_PROPERTIES_TTML_FILE);
-    assertEquals(2, subtitle.getEventTimeCount());
-
-    TtmlNode root = subtitle.getRoot();
-
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode firstDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
-    TtmlNode firstPStyle = queryChildrenForTag(firstDiv, TtmlNode.TAG_P, 0);
-    TtmlStyle spanStyle = queryChildrenForTag(firstPStyle, TtmlNode.TAG_SPAN, 0).style;
-
-    assertFalse("background color must not be inherited from a context node",
-        spanStyle.hasBackgroundColorSpecified());
+    assertSpans(subtitle, 10, "text 1", "sansSerif", TtmlStyle.STYLE_NORMAL,
+        Color.RED, Color.parseColor("lime"), false, true, Layout.Alignment.ALIGN_CENTER);
+    assertSpans(subtitle, 20, "text 2", "serif", TtmlStyle.STYLE_BOLD_ITALIC,
+        Color.BLUE, Color.YELLOW, true, true, Layout.Alignment.ALIGN_CENTER);
   }
 
   public void testInheritMultipleStyles() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_MULTIPLE_STYLES_TTML_FILE);
     assertEquals(12, subtitle.getEventTimeCount());
 
-    TtmlNode root = subtitle.getRoot();
-
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode firstDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
-    TtmlStyle firstPStyle = queryChildrenForTag(firstDiv, TtmlNode.TAG_P, 0).style;
-
-    assertEquals(Color.parseColor("blue"), firstPStyle.getBackgroundColor());
-    assertEquals(Color.parseColor("yellow"), firstPStyle.getColor());
-    assertEquals("sansSerif", firstPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, firstPStyle.getStyle());
-    assertTrue(firstPStyle.isLinethrough());
+    assertSpans(subtitle, 10, "text 1", "sansSerif", TtmlStyle.STYLE_BOLD_ITALIC,
+        Color.BLUE, Color.YELLOW, false, true, null);
   }
 
   public void testInheritMultipleStylesWithoutLocalAttributes() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_MULTIPLE_STYLES_TTML_FILE);
     assertEquals(12, subtitle.getEventTimeCount());
 
-    TtmlNode root = subtitle.getRoot();
-
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode secondDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 1);
-    TtmlStyle firstPStyle = queryChildrenForTag(secondDiv, TtmlNode.TAG_P, 0).style;
-
-    assertEquals(Color.parseColor("blue"), firstPStyle.getBackgroundColor());
-    assertEquals(Color.parseColor("black"), firstPStyle.getColor());
-    assertEquals("sansSerif", firstPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, firstPStyle.getStyle());
-    assertTrue(firstPStyle.isLinethrough());
+    assertSpans(subtitle, 20, "text 2", "sansSerif", TtmlStyle.STYLE_BOLD_ITALIC,
+        Color.BLUE, Color.BLACK, false, true, null);
 
   }
 
@@ -211,21 +129,8 @@ public final class TtmlParserTest extends InstrumentationTestCase {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_MULTIPLE_STYLES_TTML_FILE);
     assertEquals(12, subtitle.getEventTimeCount());
 
-    TtmlNode root = subtitle.getRoot();
-
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode thirdDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 2);
-    TtmlStyle firstPStyle = queryChildrenForTag(thirdDiv, TtmlNode.TAG_P, 0).style;
-
-    // inherit from first global style
-    assertEquals(Color.parseColor("red"), firstPStyle.getBackgroundColor());
-    // inherit from second global style
-    assertTrue(firstPStyle.isLinethrough());
-    // inherited from parent node
-    assertEquals("sansSerifInline", firstPStyle.getFontFamily());
-    assertEquals(TtmlStyle.STYLE_ITALIC, firstPStyle.getStyle());
-    assertTrue(firstPStyle.isUnderline());
-    assertEquals(Color.parseColor("yellow"), firstPStyle.getColor());
+    assertSpans(subtitle, 30, "text 2.5", "sansSerifInline", TtmlStyle.STYLE_ITALIC,
+        Color.RED, Color.YELLOW, true, true, null);
   }
 
   public void testEmptyStyleAttribute() throws IOException {
@@ -236,8 +141,7 @@ public final class TtmlParserTest extends InstrumentationTestCase {
     TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
     TtmlNode fourthDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 3);
 
-    // no styles specified
-    assertNull(queryChildrenForTag(fourthDiv, TtmlNode.TAG_P, 0).style);
+    assertNull(queryChildrenForTag(fourthDiv, TtmlNode.TAG_P, 0).getStyleIds());
   }
 
   public void testNonexistingStyleId() throws IOException {
@@ -248,11 +152,10 @@ public final class TtmlParserTest extends InstrumentationTestCase {
     TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
     TtmlNode fifthDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 4);
 
-    // no styles specified
-    assertNull(queryChildrenForTag(fifthDiv, TtmlNode.TAG_P, 0).style);
+    assertEquals(1, queryChildrenForTag(fifthDiv, TtmlNode.TAG_P, 0).getStyleIds().length);
   }
 
-  public void testNonExistingAndExistingStyleId() throws IOException {
+  public void testNonExistingAndExistingStyleIdWithRedundantSpaces() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INHERIT_MULTIPLE_STYLES_TTML_FILE);
     assertEquals(12, subtitle.getEventTimeCount());
 
@@ -260,28 +163,30 @@ public final class TtmlParserTest extends InstrumentationTestCase {
     TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
     TtmlNode sixthDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 5);
 
-    // no styles specified
-    TtmlStyle style = queryChildrenForTag(sixthDiv, TtmlNode.TAG_P, 0).style;
-    assertNotNull(style);
-    assertEquals(Color.RED, style.getBackgroundColor());
+    String[] styleIds = queryChildrenForTag(sixthDiv, TtmlNode.TAG_P, 0).getStyleIds();
+    assertEquals(2, styleIds.length);
   }
 
   public void testMultipleChaining() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(CHAIN_MULTIPLE_STYLES_TTML_FILE);
     assertEquals(2, subtitle.getEventTimeCount());
 
-    TtmlNode root = subtitle.getRoot();
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode div = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
+    Map<String, TtmlStyle> globalStyles = subtitle.getGlobalStyles();
 
-    // no styles specified
-    TtmlStyle style = queryChildrenForTag(div, TtmlNode.TAG_P, 0).style;
+    TtmlStyle style = globalStyles.get("s2");
     assertEquals("serif", style.getFontFamily());
     assertEquals(Color.RED, style.getBackgroundColor());
     assertEquals(Color.BLACK, style.getColor());
     assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, style.getStyle());
     assertTrue(style.isLinethrough());
 
+    style = globalStyles.get("s3");
+    // only difference: color must be RED
+    assertEquals(Color.RED, style.getColor());
+    assertEquals("serif", style.getFontFamily());
+    assertEquals(Color.RED, style.getBackgroundColor());
+    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, style.getStyle());
+    assertTrue(style.isLinethrough());
   }
 
   public void testNoUnderline() throws IOException {
@@ -309,32 +214,6 @@ public final class TtmlParserTest extends InstrumentationTestCase {
         style.isLinethrough());
   }
 
-
-  public void testOnlySingleInstance() throws IOException {
-    TtmlSubtitle subtitle = getSubtitle(INSTANCE_CREATION_TTML_FILE);
-    assertEquals(4, subtitle.getEventTimeCount());
-
-    TtmlNode root = subtitle.getRoot();
-    TtmlNode body = queryChildrenForTag(root, TtmlNode.TAG_BODY, 0);
-    TtmlNode firstDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 0);
-    TtmlNode secondDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 1);
-    TtmlNode thirdDiv = queryChildrenForTag(body, TtmlNode.TAG_DIV, 2);
-
-    TtmlNode firstP = queryChildrenForTag(firstDiv, TtmlNode.TAG_P, 0);
-    TtmlNode secondP = queryChildrenForTag(secondDiv, TtmlNode.TAG_P, 0);
-    TtmlNode secondSpan = queryChildrenForTag(secondP, TtmlNode.TAG_SPAN, 0);
-    TtmlNode thirdP = queryChildrenForTag(thirdDiv, TtmlNode.TAG_P, 0);
-    TtmlNode thirdSpan = queryChildrenForTag(secondP, TtmlNode.TAG_SPAN, 0);
-
-    // inherit the same instance down the tree if possible
-    assertSame(body.style, firstP.style);
-    assertSame(firstP.style, secondP.style);
-    assertSame(secondP.style, secondSpan.style);
-
-    // if a backgroundColor is involved it does not help
-    assertNotSame(thirdP.style.getInheritableStyle(), thirdSpan.style);
-  }
-
   public void testNamspaceConfusionDoesNotHurt() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(NAMESPACE_CONFUSION_TTML_FILE);
     assertEquals(2, subtitle.getEventTimeCount());
@@ -373,6 +252,60 @@ public final class TtmlParserTest extends InstrumentationTestCase {
 
   }
 
+  private void assertSpans(TtmlSubtitle subtitle, int second,
+      String text, String font, int fontStyle,
+      int backgroundColor, int color, boolean isUnderline,
+      boolean isLinethrough, Layout.Alignment alignment) {
+
+    long timeUs = second * 1000000;
+    List<Cue> cues = subtitle.getCues(timeUs);
+
+    assertEquals(1, cues.size());
+    assertEquals(text, String.valueOf(cues.get(0).text));
+
+    assertEquals("single cue expected for timeUs: " + timeUs, 1, cues.size());
+    SpannableStringBuilder spannable = (SpannableStringBuilder) cues.get(0).text;
+
+    TypefaceSpan[] typefaceSpans = spannable.getSpans(0, spannable.length(), TypefaceSpan.class);
+    assertEquals(font, typefaceSpans[typefaceSpans.length - 1].getFamily());
+
+    StyleSpan[] styleSpans = spannable.getSpans(0, spannable.length(), StyleSpan.class);
+    assertEquals(fontStyle, styleSpans[styleSpans.length - 1].getStyle());
+
+    UnderlineSpan[] underlineSpans = spannable.getSpans(0, spannable.length(),
+        UnderlineSpan.class);
+    assertEquals(isUnderline ? "must be underlined" : "must not be underlined",
+        isUnderline ? 1 : 0, underlineSpans.length);
+
+    StrikethroughSpan[] striketroughSpans = spannable.getSpans(0, spannable.length(),
+        StrikethroughSpan.class);
+    assertEquals(isLinethrough ? "must be strikethrough" : "must not be strikethrough",
+        isLinethrough ? 1 : 0, striketroughSpans.length);
+
+    BackgroundColorSpan[] backgroundColorSpans =
+        spannable.getSpans(0, spannable.length(), BackgroundColorSpan.class);
+    if (backgroundColor != 0) {
+      assertEquals(backgroundColor, backgroundColorSpans[backgroundColorSpans.length - 1]
+          .getBackgroundColor());
+    } else {
+      assertEquals(0, backgroundColorSpans.length);
+    }
+
+    ForegroundColorSpan[] foregroundColorSpans =
+        spannable.getSpans(0, spannable.length(), ForegroundColorSpan.class);
+    assertEquals(color, foregroundColorSpans[foregroundColorSpans.length - 1].getForegroundColor());
+
+    if (alignment != null) {
+      AlignmentSpan.Standard[] alignmentSpans =
+          spannable.getSpans(0, spannable.length(), AlignmentSpan.Standard.class);
+      assertEquals(1, alignmentSpans.length);
+      assertEquals(alignment, alignmentSpans[0].getAlignment());
+    } else {
+      assertEquals(0, spannable.getSpans
+          (0, spannable.length(), AlignmentSpan.Standard.class).length);
+    }
+  }
+
   private TtmlNode queryChildrenForTag(TtmlNode node, String tag, int pos) {
     int count = 0;
     for (int i = 0; i < node.getChildCount(); i++) {
diff --git a/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtilTest.java b/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtilTest.java
new file mode 100644
index 0000000000..bdfeda663b
--- /dev/null
+++ b/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtilTest.java
@@ -0,0 +1,111 @@
+package com.google.android.exoplayer.text.ttml;
+/*
+ * Copyright (C) 2015 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.
+ */
+
+import android.graphics.Color;
+import android.test.InstrumentationTestCase;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Unit test for <code>TtmlRenderUtil</code>
+ */
+public class TtmlRenderUtilTest extends InstrumentationTestCase {
+
+  public void testResolveStyleNoStyleAtAll() {
+    assertNull(TtmlRenderUtil.resolveStyle(null, null, null));
+  }
+  public void testResolveStyleSingleReferentialStyle() {
+    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
+    String[] styleIds = {"s0"};
+
+    assertSame(globalStyles.get("s0"),
+        TtmlRenderUtil.resolveStyle(null, styleIds, globalStyles));
+  }
+  public void testResolveStyleMultipleReferentialStyles() {
+    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
+    String[] styleIds = {"s0", "s1"};
+
+    TtmlStyle resolved = TtmlRenderUtil.resolveStyle(null, styleIds, globalStyles);
+    assertNotSame(globalStyles.get("s0"), resolved);
+    assertNotSame(globalStyles.get("s1"), resolved);
+    assertNull(resolved.getId());
+
+    // inherited from s0
+    assertEquals(Color.BLACK, resolved.getBackgroundColor());
+    // inherited from s1
+    assertEquals(Color.RED, resolved.getColor());
+    // merged from s0 and s1
+    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, resolved.getStyle());
+  }
+
+  public void testResolveMergeSingleReferentialStyleIntoInlineStyle() {
+    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
+    String[] styleIds = {"s0"};
+    TtmlStyle style = new TtmlStyle();
+    style.setBackgroundColor(Color.YELLOW);
+
+    TtmlStyle resolved = TtmlRenderUtil.resolveStyle(style, styleIds, globalStyles);
+    assertSame(style, resolved);
+
+    // inline attribute not overridden
+    assertEquals(Color.YELLOW, resolved.getBackgroundColor());
+    // inherited from referential style
+    assertEquals(TtmlStyle.STYLE_BOLD, resolved.getStyle());
+  }
+
+
+  public void testResolveMergeMultipleReferentialStylesIntoInlineStyle() {
+    Map<String, TtmlStyle> globalStyles = getGlobalStyles();
+    String[] styleIds = {"s0", "s1"};
+    TtmlStyle style = new TtmlStyle();
+    style.setBackgroundColor(Color.YELLOW);
+
+    TtmlStyle resolved = TtmlRenderUtil.resolveStyle(style, styleIds, globalStyles);
+    assertSame(style, resolved);
+
+    // inline attribute not overridden
+    assertEquals(Color.YELLOW, resolved.getBackgroundColor());
+    // inherited from both referential style
+    assertEquals(TtmlStyle.STYLE_BOLD_ITALIC, resolved.getStyle());
+  }
+
+  public void testResolveStyleOnlyInlineStyle() {
+    TtmlStyle inlineStyle = new TtmlStyle();
+    assertSame(inlineStyle, TtmlRenderUtil.resolveStyle(inlineStyle, null, null));
+  }
+
+  private Map<String, TtmlStyle> getGlobalStyles() {
+    Map<String, TtmlStyle> globalStyles = new HashMap<>();
+
+    TtmlStyle s0 = new TtmlStyle();
+    s0.setId("s0");
+    s0.setBackgroundColor(Color.BLACK);
+    s0.setBold(true);
+    globalStyles.put(s0.getId(), s0);
+
+    TtmlStyle s1 = new TtmlStyle();
+    s1.setId("s1");
+    s1.setBackgroundColor(Color.RED);
+    s1.setColor(Color.RED);
+    s1.setItalic(true);
+    globalStyles.put(s1.getId(), s1);
+
+    return globalStyles;
+  }
+
+}
diff --git a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlNode.java b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlNode.java
index 0eb282db5c..d393875c57 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlNode.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlNode.java
@@ -15,20 +15,12 @@
  */
 package com.google.android.exoplayer.text.ttml;
 
-import android.text.Spannable;
 import android.text.SpannableStringBuilder;
-import android.text.Spanned;
-import android.text.style.AlignmentSpan;
-import android.text.style.BackgroundColorSpan;
-import android.text.style.ForegroundColorSpan;
-import android.text.style.StrikethroughSpan;
-import android.text.style.StyleSpan;
-import android.text.style.TypefaceSpan;
-import android.text.style.UnderlineSpan;
 
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Map;
 import java.util.TreeSet;
 
 /**
@@ -82,22 +74,28 @@ import java.util.TreeSet;
   public final long startTimeUs;
   public final long endTimeUs;
   public final TtmlStyle style;
+  private String[] styleIds;
 
   private List<TtmlNode> children;
+  private int start;
+  private int end;
 
-  public static TtmlNode buildTextNode(String text, TtmlStyle style) {
-    return new TtmlNode(null, applyTextElementSpacePolicy(text), UNDEFINED_TIME,
-        UNDEFINED_TIME, style);
+  public static TtmlNode buildTextNode(String text) {
+    return new TtmlNode(null, TtmlRenderUtil.applyTextElementSpacePolicy(text), UNDEFINED_TIME,
+        UNDEFINED_TIME, null, null);
   }
 
-  public static TtmlNode buildNode(String tag, long startTimeUs, long endTimeUs, TtmlStyle style) {
-    return new TtmlNode(tag, null, startTimeUs, endTimeUs, style);
+  public static TtmlNode buildNode(String tag, long startTimeUs, long endTimeUs,
+      TtmlStyle style, String[] styleIds) {
+    return new TtmlNode(tag, null, startTimeUs, endTimeUs, style, styleIds);
   }
 
-  private TtmlNode(String tag, String text, long startTimeUs, long endTimeUs, TtmlStyle style) {
+  private TtmlNode(String tag, String text, long startTimeUs, long endTimeUs,
+      TtmlStyle style, String[] styleIds) {
     this.tag = tag;
     this.text = text;
     this.style = style;
+    this.styleIds = styleIds;
     this.isTextNode = text != null;
     this.startTimeUs = startTimeUs;
     this.endTimeUs = endTimeUs;
@@ -159,8 +157,14 @@ import java.util.TreeSet;
     }
   }
 
-  public CharSequence getText(long timeUs) {
-    SpannableStringBuilder builder = getText(timeUs, new SpannableStringBuilder(), false);
+  public String[] getStyleIds() {
+    return styleIds;
+  }
+
+  public CharSequence getText(long timeUs, Map<String, TtmlStyle> globalStyles) {
+    SpannableStringBuilder builder = new SpannableStringBuilder();
+    traverseForText(timeUs, builder, false);
+    traverseForStyle(builder, globalStyles);
     // Having joined the text elements, we need to do some final cleanup on the result.
     // 1. Collapse multiple consecutive spaces into a single space.
     int builderLength = builder.length();
@@ -208,12 +212,12 @@ import java.util.TreeSet;
     return builder;
   }
 
-  private SpannableStringBuilder getText(long timeUs, SpannableStringBuilder builder,
+  private SpannableStringBuilder traverseForText(long timeUs, SpannableStringBuilder builder,
       boolean descendsPNode) {
+    start = builder.length();
+    end = start;
     if (isTextNode && descendsPNode) {
-      int start = builder.length();
       builder.append(text);
-      applyStylesToSpan(builder, start, builder.length(), style);
     } else if (TAG_BR.equals(tag) && descendsPNode) {
       builder.append('\n');
     } else if (TAG_METADATA.equals(tag)) {
@@ -221,79 +225,27 @@ import java.util.TreeSet;
     } else if (isActive(timeUs)) {
       boolean isPNode = TAG_P.equals(tag);
       for (int i = 0; i < getChildCount(); ++i) {
-        getChild(i).getText(timeUs, builder, descendsPNode || isPNode);
+        getChild(i).traverseForText(timeUs, builder, descendsPNode || isPNode);
       }
       if (isPNode) {
-        endParagraph(builder);
+        TtmlRenderUtil.endParagraph(builder);
       }
+      end = builder.length();
     }
     return builder;
   }
 
-  private static void applyStylesToSpan(SpannableStringBuilder builder,
-      int start, int end, TtmlStyle style) {
-
-    if (style.getStyle() != TtmlStyle.UNSPECIFIED) {
-      builder.setSpan(new StyleSpan(style.getStyle()), start, end,
-          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+  private void traverseForStyle(SpannableStringBuilder builder,
+      Map<String, TtmlStyle> globalStyles) {
+    if (start != end) {
+      TtmlStyle resolvedStyle = TtmlRenderUtil.resolveStyle(style, styleIds, globalStyles);
+      if (resolvedStyle != null) {
+        TtmlRenderUtil.applyStylesToSpan(builder, start, end, resolvedStyle);
+      }
+      for (int i = 0; i < getChildCount(); ++i) {
+        getChild(i).traverseForStyle(builder, globalStyles);
+      }
     }
-    if (style.isLinethrough()) {
-      builder.setSpan(new StrikethroughSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
-    if (style.isUnderline()) {
-      builder.setSpan(new UnderlineSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
-    if (style.hasColorSpecified()) {
-      builder.setSpan(new ForegroundColorSpan(style.getColor()), start, end,
-          Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
-    if (style.hasBackgroundColorSpecified()) {
-      builder.setSpan(new BackgroundColorSpan(style.getBackgroundColor()), start, end,
-          Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
-    if (style.getFontFamily() != null) {
-      builder.setSpan(new TypefaceSpan(style.getFontFamily()), start, end,
-          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
-    if (style.getTextAlign() != null) {
-      builder.setSpan(new AlignmentSpan.Standard(style.getTextAlign()), start, end,
-          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
-    }
-  }
-
-  /**
-   * Invoked when the end of a paragraph is encountered. Adds a newline if there are one or more
-   * non-space characters since the previous newline.
-   *
-   * @param builder The builder.
-   */
-  private static void endParagraph(SpannableStringBuilder builder) {
-    int position = builder.length() - 1;
-    while (position >= 0 && builder.charAt(position) == ' ') {
-      position--;
-    }
-    if (position >= 0 && builder.charAt(position) != '\n') {
-      builder.append('\n');
-    }
-  }
-
-  /**
-   * Applies the appropriate space policy to the given text element.
-   *
-   * @param in The text element to which the policy should be applied.
-   * @return The result of applying the policy to the text element.
-   */
-  private static String applyTextElementSpacePolicy(String in) {
-    // Removes carriage return followed by line feed. See: http://www.w3.org/TR/xml/#sec-line-ends
-    String out = in.replaceAll("\r\n", "\n");
-    // Apply suppress-at-line-break="auto" and
-    // white-space-treatment="ignore-if-surrounding-linefeed"
-    out = out.replaceAll(" *\n *", "\n");
-    // Apply linefeed-treatment="treat-as-space"
-    out = out.replaceAll("\n", " ");
-    // Apply white-space-collapse="true"
-    out = out.replaceAll("[ \t\\x0B\f\r]+", " ");
-    return out;
   }
 
 }
diff --git a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java
index 2379eed5bf..a9e6c1b99a 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlParser.java
@@ -127,7 +127,7 @@ public final class TtmlParser implements SubtitleParser {
               parseHeader(xmlParser, globalStyles);
             } else {
               try {
-                TtmlNode node = parseNode(xmlParser, parent, globalStyles);
+                TtmlNode node = parseNode(xmlParser, parent);
                 nodeStack.addLast(node);
                 if (parent != null) {
                   parent.addChild(node);
@@ -143,10 +143,10 @@ public final class TtmlParser implements SubtitleParser {
               }
             }
           } else if (eventType == XmlPullParser.TEXT) {
-            parent.addChild(TtmlNode.buildTextNode(xmlParser.getText(), parent.style));
+            parent.addChild(TtmlNode.buildTextNode(xmlParser.getText()));
           } else if (eventType == XmlPullParser.END_TAG) {
             if (xmlParser.getName().equals(TtmlNode.TAG_TT)) {
-              ttmlSubtitle = new TtmlSubtitle(nodeStack.getLast());
+              ttmlSubtitle = new TtmlSubtitle(nodeStack.getLast(), globalStyles);
             }
             nodeStack.removeLast();
           }
@@ -176,7 +176,7 @@ public final class TtmlParser implements SubtitleParser {
         String parentStyleId = xmlParser.getAttributeValue(null, ATTR_STYLE);
         TtmlStyle style = parseStyleAttributes(xmlParser, new TtmlStyle());
         if (parentStyleId != null) {
-          String[] ids = parentStyleId.split(" ");
+          String[] ids = parseStyleIds(parentStyleId);
           for (int i = 0; i < ids.length; i++) {
             style.chain(globalStyles.get(ids[i]));
           }
@@ -189,6 +189,10 @@ public final class TtmlParser implements SubtitleParser {
     return globalStyles;
   }
 
+  private String[] parseStyleIds(String parentStyleIds) {
+    return parentStyleIds.split("\\s+");
+  }
+
   private TtmlStyle parseStyleAttributes(XmlPullParser parser, TtmlStyle style) {
     int attributeCount = parser.getAttributeCount();
     for (int i = 0; i < attributeCount; i++) {
@@ -282,23 +286,14 @@ public final class TtmlParser implements SubtitleParser {
     return MimeTypes.APPLICATION_TTML.equals(mimeType);
   }
 
-  private TtmlNode parseNode(XmlPullParser parser, TtmlNode parent,
-      Map<String, TtmlStyle> globalStyles) throws ParserException {
+  private TtmlNode parseNode(XmlPullParser parser, TtmlNode parent) throws ParserException {
     long duration = 0;
     long startTime = TtmlNode.UNDEFINED_TIME;
     long endTime = TtmlNode.UNDEFINED_TIME;
+    String[] styleIds = null;
     int attributeCount = parser.getAttributeCount();
     TtmlStyle style = parseStyleAttributes(parser, null);
-    boolean hasInlineStyles = style != null;
-    if (parent != null && parent.style != null) {
-      if (hasInlineStyles) {
-        style.inherit(parent.style);
-      } else {
-        style = parent.style.getInheritableStyle();
-      }
-    }
     for (int i = 0; i < attributeCount; i++) {
-      // TODO: check if it is safe to remove the namespace prefix
       String attr = ParserUtil.removeNamespacePrefix(parser.getAttributeName(i));
       String value = parser.getAttributeValue(i);
       if (attr.equals(ATTR_BEGIN)) {
@@ -312,32 +307,10 @@ public final class TtmlParser implements SubtitleParser {
             DEFAULT_FRAMERATE, DEFAULT_SUBFRAMERATE, DEFAULT_TICKRATE);
       } else if (attr.equals(ATTR_STYLE)) {
         // IDREFS: potentially multiple space delimited ids
-        String[] ids = value.split(" ");
-        if (style == null) {
-          // use global style without overriding
-          if (ids.length == 1) {
-            style = globalStyles.get(value);
-          } else if (ids.length > 1){
-            style = new TtmlStyle();
-            for (int j = 0; j < ids.length; j++) {
-              style.chain(globalStyles.get(ids[j]));
-            }
-          }
-        } else if (hasInlineStyles) {
-          // local attributes inherits from global style
-          for (int j = 0; j < ids.length; j++) {
-            style.chain(globalStyles.get(ids[j]));
-          }
-        } else if (ids.length > 1 || (ids.length == 1 && style != globalStyles.get(ids[0]))) {
-          // merge global style and parent styles
-          TtmlStyle inheritedStyles = style;
-          style = new TtmlStyle();
-          for (int j = 0; j < ids.length; j++) {
-            style.chain(globalStyles.get(ids[j]));
-          }
-          style.inherit(inheritedStyles);
+        String[] ids = parseStyleIds(value);
+        if (ids.length > 0) {
+          styleIds = ids;
         }
-
       } else {
         // Do nothing.
       }
@@ -359,7 +332,7 @@ public final class TtmlParser implements SubtitleParser {
         endTime = parent.endTimeUs;
       }
     }
-    return TtmlNode.buildNode(parser.getName(), startTime, endTime, style);
+    return TtmlNode.buildNode(parser.getName(), startTime, endTime, style, styleIds);
   }
 
   private static boolean isSupportedTag(String tag) {
diff --git a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtil.java b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtil.java
new file mode 100644
index 0000000000..638e47d276
--- /dev/null
+++ b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlRenderUtil.java
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2015 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.exoplayer.text.ttml;
+
+import android.text.Spannable;
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+import android.text.style.AlignmentSpan;
+import android.text.style.BackgroundColorSpan;
+import android.text.style.ForegroundColorSpan;
+import android.text.style.StrikethroughSpan;
+import android.text.style.StyleSpan;
+import android.text.style.TypefaceSpan;
+import android.text.style.UnderlineSpan;
+
+import java.util.Map;
+
+/**
+ * Package internal utility class to render styled <code>TtmlNode</code>s.
+ */
+/* package */ final class TtmlRenderUtil {
+
+  /* spans which are always the same can be reused to avoid object creation */
+  private static final StrikethroughSpan STRIKETHROUGH_SPAN = new StrikethroughSpan();
+  private static final UnderlineSpan UNDERLINE_SPAN = new UnderlineSpan();
+  private static final StyleSpan[] STYLE_SPANS = new StyleSpan[] {
+    new StyleSpan(TtmlStyle.STYLE_NORMAL),
+    new StyleSpan(TtmlStyle.STYLE_BOLD),
+    new StyleSpan(TtmlStyle.STYLE_ITALIC),
+    new StyleSpan(TtmlStyle.STYLE_BOLD_ITALIC),
+  };
+
+  public static TtmlStyle resolveStyle(TtmlStyle style, String[] styleIds,
+      Map<String, TtmlStyle> globalStyles) {
+    if (style == null && styleIds == null) {
+      // no styles at all
+      return null;
+    } else if (style == null && styleIds.length == 1) {
+      // only one single referential style present
+      return globalStyles.get(styleIds[0]);
+    } else if (style == null && styleIds.length > 1) {
+      // only multiple referential styles present
+      TtmlStyle chainedStyle = new TtmlStyle();
+      for (int i = 0; i < styleIds.length; i++) {
+        chainedStyle.chain(globalStyles.get(styleIds[i]));
+      }
+      return chainedStyle;
+    } else if (style != null && styleIds != null && styleIds.length == 1) {
+      // merge a single referential style into inline style
+      return style.chain(globalStyles.get(styleIds[0]));
+    } else if (style != null && styleIds != null && styleIds.length > 1) {
+      // merge multiple referential styles into inline style
+      for (int i = 0; i < styleIds.length; i++) {
+        style.chain(globalStyles.get(styleIds[i]));
+      }
+      return style;
+    }
+    // only inline styles available
+    return style;
+  }
+
+  public static void applyStylesToSpan(SpannableStringBuilder builder,
+      int start, int end, TtmlStyle style) {
+
+    if (style.getStyle() != TtmlStyle.UNSPECIFIED) {
+      builder.setSpan(STYLE_SPANS[style.getStyle()], start, end,
+          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+    if (style.isLinethrough()) {
+      builder.setSpan(STRIKETHROUGH_SPAN, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+    if (style.isUnderline()) {
+      builder.setSpan(UNDERLINE_SPAN, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+    if (style.hasColorSpecified()) {
+      builder.setSpan(new ForegroundColorSpan(style.getColor()), start, end,
+          Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+    if (style.hasBackgroundColorSpecified()) {
+      builder.setSpan(new BackgroundColorSpan(style.getBackgroundColor()), start, end,
+          Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+    if (style.getFontFamily() != null) {
+      builder.setSpan(new TypefaceSpan(style.getFontFamily()), start, end,
+          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+    if (style.getTextAlign() != null) {
+      builder.setSpan(new AlignmentSpan.Standard(style.getTextAlign()), start, end,
+          Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+    }
+  }
+
+  /**
+   * Invoked when the end of a paragraph is encountered. Adds a newline if there are one or more
+   * non-space characters since the previous newline.
+   *
+   * @param builder The builder.
+   */
+  /* package */ static void endParagraph(SpannableStringBuilder builder) {
+    int position = builder.length() - 1;
+    while (position >= 0 && builder.charAt(position) == ' ') {
+      position--;
+    }
+    if (position >= 0 && builder.charAt(position) != '\n') {
+      builder.append('\n');
+    }
+  }
+
+  /**
+   * Applies the appropriate space policy to the given text element.
+   *
+   * @param in The text element to which the policy should be applied.
+   * @return The result of applying the policy to the text element.
+   */
+  /* package */ static String applyTextElementSpacePolicy(String in) {
+    // Removes carriage return followed by line feed. See: http://www.w3.org/TR/xml/#sec-line-ends
+    String out = in.replaceAll("\r\n", "\n");
+    // Apply suppress-at-line-break="auto" and
+    // white-space-treatment="ignore-if-surrounding-linefeed"
+    out = out.replaceAll(" *\n *", "\n");
+    // Apply linefeed-treatment="treat-as-space"
+    out = out.replaceAll("\n", " ");
+    // Apply white-space-collapse="true"
+    out = out.replaceAll("[ \t\\x0B\f\r]+", " ");
+    return out;
+  }
+
+  private TtmlRenderUtil() {}
+
+}
diff --git a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlSubtitle.java b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlSubtitle.java
index f29338cd43..a989bf86f8 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlSubtitle.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlSubtitle.java
@@ -21,6 +21,7 @@ import com.google.android.exoplayer.util.Util;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 
 /**
  * A representation of a TTML subtitle.
@@ -29,9 +30,12 @@ public final class TtmlSubtitle implements Subtitle {
 
   private final TtmlNode root;
   private final long[] eventTimesUs;
+  private final Map<String, TtmlStyle> globalStyles;
 
-  public TtmlSubtitle(TtmlNode root) {
+  public TtmlSubtitle(TtmlNode root, Map<String, TtmlStyle> globalStyles) {
     this.root = root;
+    this.globalStyles = globalStyles != null
+        ? Collections.unmodifiableMap(globalStyles) : Collections.<String, TtmlStyle>emptyMap();
     this.eventTimesUs = root.getEventTimesUs();
   }
 
@@ -63,7 +67,7 @@ public final class TtmlSubtitle implements Subtitle {
 
   @Override
   public List<Cue> getCues(long timeUs) {
-    CharSequence cueText = root.getText(timeUs);
+    CharSequence cueText = root.getText(timeUs, globalStyles);
     if (cueText == null) {
       return Collections.<Cue>emptyList();
     } else {
@@ -72,4 +76,8 @@ public final class TtmlSubtitle implements Subtitle {
     }
   }
 
+  /* @VisibleForTesting */
+  /* package */ Map<String, TtmlStyle> getGlobalStyles() {
+    return globalStyles;
+  }
 }
