From b766253116d687e15c6052e3ef25d1b419933973 Mon Sep 17 00:00:00 2001
From: Oliver Woodman <olly@google.com>
Date: Mon, 26 Oct 2015 15:23:06 +0000
Subject: [PATCH] m

---
 .../src/androidTest/assets/ttml/font_size.xml |  30 ++++
 .../assets/ttml/font_size_empty.xml           |  10 ++
 .../assets/ttml/font_size_invalid.xml         |  16 ++
 .../assets/ttml/font_size_no_unit.xml         |  10 ++
 .../exoplayer/text/ttml/TtmlParserTest.java   | 142 +++++++++++++++++-
 .../exoplayer/text/ttml/TtmlStyleTest.java    |  23 ---
 .../exoplayer/text/ttml/TtmlParser.java       |  43 +++++-
 .../exoplayer/text/ttml/TtmlRenderUtil.java   |  18 +++
 .../exoplayer/text/ttml/TtmlStyle.java        |  44 ++++--
 9 files changed, 293 insertions(+), 43 deletions(-)
 create mode 100644 library/src/androidTest/assets/ttml/font_size.xml
 create mode 100644 library/src/androidTest/assets/ttml/font_size_empty.xml
 create mode 100644 library/src/androidTest/assets/ttml/font_size_invalid.xml
 create mode 100644 library/src/androidTest/assets/ttml/font_size_no_unit.xml
diff --git a/library/src/androidTest/assets/ttml/font_size.xml b/library/src/androidTest/assets/ttml/font_size.xml
new file mode 100644
index 0000000000..adbb8d6926
--- /dev/null
+++ b/library/src/androidTest/assets/ttml/font_size.xml
@@ -0,0 +1,30 @@
+<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:textDecoration="underline"/>
+      <style id="s1"
+        tts:textDecoration="lineThrough"/>
+    </styling>
+  </head>
+  <body>
+    <div>
+      <p begin="10s" end="18s" tts:fontSize="32px">text 1</p>
+    </div>
+    <div>
+      <p begin="20s" end="28s" tts:fontSize="2.2em">text 2</p>
+    </div>
+    <div>
+      <p begin="30s" end="38s" tts:fontSize="150%">text 3</p>
+    </div>
+    <div>
+      <p begin="40s" end="48s" tts:fontSize="32px 16px">two values</p>
+    </div>
+    <div>
+      <p begin="50s" end="58s" tts:fontSize=".5em">leading dot</p>
+    </div>
+  </body>
+</tt>
diff --git a/library/src/androidTest/assets/ttml/font_size_empty.xml b/library/src/androidTest/assets/ttml/font_size_empty.xml
new file mode 100644
index 0000000000..fdfc03ea6d
--- /dev/null
+++ b/library/src/androidTest/assets/ttml/font_size_empty.xml
@@ -0,0 +1,10 @@
+<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:fontSize="">empty</p>
+    </div>
+  </body>
+</tt>
diff --git a/library/src/androidTest/assets/ttml/font_size_invalid.xml b/library/src/androidTest/assets/ttml/font_size_invalid.xml
new file mode 100644
index 0000000000..2635656445
--- /dev/null
+++ b/library/src/androidTest/assets/ttml/font_size_invalid.xml
@@ -0,0 +1,16 @@
+<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:fontSize="px">invalid</p>
+    </div>
+    <div>
+      <p begin="20s" end="28s" tts:fontSize="12px 10px 9px">invalid</p>
+    </div>
+    <div>
+      <p begin="30s" end="38s" tts:fontSize="1.em">invalid dot</p>
+    </div>
+  </body>
+</tt>
diff --git a/library/src/androidTest/assets/ttml/font_size_no_unit.xml b/library/src/androidTest/assets/ttml/font_size_no_unit.xml
new file mode 100644
index 0000000000..126bd1ff33
--- /dev/null
+++ b/library/src/androidTest/assets/ttml/font_size_no_unit.xml
@@ -0,0 +1,10 @@
+<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:fontSize="32">no unit</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 4133c3ce3d..8434a2e59b 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
@@ -19,10 +19,13 @@ import com.google.android.exoplayer.text.Cue;
 
 import android.test.InstrumentationTestCase;
 import android.text.Layout;
+import android.text.Spannable;
 import android.text.SpannableStringBuilder;
+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;
 import android.text.style.StrikethroughSpan;
 import android.text.style.StyleSpan;
 import android.text.style.TypefaceSpan;
@@ -56,6 +59,14 @@ public final class TtmlParserTest extends InstrumentationTestCase {
       "ttml/namespace_confusion.xml";
   private static final String NAMESPACE_NOT_DECLARED_TTML_FILE =
       "ttml/namespace_not_declared.xml";
+  private static final String FONT_SIZE_TTML_FILE =
+      "ttml/font_size.xml";
+  private static final String FONT_SIZE_MISSING_UNIT_TTML_FILE =
+      "ttml/font_size_no_unit.xml";
+  private static final String FONT_SIZE_INVALID_TTML_FILE =
+      "ttml/font_size_invalid.xml";
+  private static final String FONT_SIZE_EMPTY_TTML_FILE =
+      "ttml/font_size_empty.xml";
 
   public void testInlineAttributes() throws IOException {
     TtmlSubtitle subtitle = getSubtitle(INLINE_ATTRIBUTES_TTML_FILE);
@@ -268,7 +279,91 @@ public final class TtmlParserTest extends InstrumentationTestCase {
     assertEquals("sansSerif", style.getFontFamily());
     assertFalse(style.isUnderline());
     assertTrue(style.isLinethrough());
+  }
 
+  public void testFontSizeSpans() throws IOException {
+    TtmlSubtitle subtitle = getSubtitle(FONT_SIZE_TTML_FILE);
+    assertEquals(10, subtitle.getEventTimeCount());
+
+    List<Cue> cues = subtitle.getCues(10 * 1000000);
+    assertEquals(1, cues.size());
+    SpannableStringBuilder spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("text 1", String.valueOf(spannable));
+    assertAbsoluteFontSize(spannable, 32);
+
+    cues = subtitle.getCues(20 * 1000000);
+    assertEquals(1, cues.size());
+    spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("text 2", String.valueOf(cues.get(0).text));
+    assertRelativeFontSize(spannable, 2.2f);
+
+    cues = subtitle.getCues(30 * 1000000);
+    assertEquals(1, cues.size());
+    spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("text 3", String.valueOf(cues.get(0).text));
+    assertRelativeFontSize(spannable, 1.5f);
+
+    cues = subtitle.getCues(40 * 1000000);
+    assertEquals(1, cues.size());
+    spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("two values", String.valueOf(cues.get(0).text));
+    assertAbsoluteFontSize(spannable, 16);
+
+    cues = subtitle.getCues(50 * 1000000);
+    assertEquals(1, cues.size());
+    spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("leading dot", String.valueOf(cues.get(0).text));
+    assertRelativeFontSize(spannable, 0.5f);
+  }
+
+  public void testFontSizeWithMissingUnitIsIgnored() throws IOException {
+    TtmlSubtitle subtitle = getSubtitle(FONT_SIZE_MISSING_UNIT_TTML_FILE);
+    assertEquals(2, subtitle.getEventTimeCount());
+    List<Cue> cues = subtitle.getCues(10 * 1000000);
+    assertEquals(1, cues.size());
+    SpannableStringBuilder spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("no unit", String.valueOf(spannable));
+    assertEquals(0, spannable.getSpans(0, spannable.length(), RelativeSizeSpan.class).length);
+    assertEquals(0, spannable.getSpans(0, spannable.length(), AbsoluteSizeSpan.class).length);
+  }
+
+  public void testFontSizeWithInvalidValueIsIgnored() throws IOException {
+    TtmlSubtitle subtitle = getSubtitle(FONT_SIZE_INVALID_TTML_FILE);
+    assertEquals(6, subtitle.getEventTimeCount());
+
+    List<Cue> cues = subtitle.getCues(10 * 1000000);
+    assertEquals(1, cues.size());
+    SpannableStringBuilder spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("invalid", String.valueOf(spannable));
+    assertEquals(0, spannable.getSpans(0, spannable.length(), RelativeSizeSpan.class).length);
+    assertEquals(0, spannable.getSpans(0, spannable.length(), AbsoluteSizeSpan.class).length);
+
+
+    cues = subtitle.getCues(20 * 1000000);
+    assertEquals(1, cues.size());
+    spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("invalid", String.valueOf(spannable));
+    assertEquals(0, spannable.getSpans(0, spannable.length(), RelativeSizeSpan.class).length);
+    assertEquals(0, spannable.getSpans(0, spannable.length(), AbsoluteSizeSpan.class).length);
+
+
+    cues = subtitle.getCues(30 * 1000000);
+    assertEquals(1, cues.size());
+    spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("invalid dot", String.valueOf(spannable));
+    assertEquals(0, spannable.getSpans(0, spannable.length(), RelativeSizeSpan.class).length);
+    assertEquals(0, spannable.getSpans(0, spannable.length(), AbsoluteSizeSpan.class).length);
+  }
+
+  public void testFontSizeWithEmptyValueIsIgnored() throws IOException {
+    TtmlSubtitle subtitle = getSubtitle(FONT_SIZE_EMPTY_TTML_FILE);
+    assertEquals(2, subtitle.getEventTimeCount());
+    List<Cue> cues = subtitle.getCues(10 * 1000000);
+    assertEquals(1, cues.size());
+    SpannableStringBuilder spannable = (SpannableStringBuilder) cues.get(0).text;
+    assertEquals("empty", String.valueOf(spannable));
+    assertEquals(0, spannable.getSpans(0, spannable.length(), RelativeSizeSpan.class).length);
+    assertEquals(0, spannable.getSpans(0, spannable.length(), AbsoluteSizeSpan.class).length);
   }
 
   private void assertSpans(TtmlSubtitle subtitle, int second,
@@ -281,26 +376,58 @@ public final class TtmlParserTest extends InstrumentationTestCase {
 
     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;
 
+    assertFont(spannable, font);
+    assertStyle(spannable, fontStyle);
+    assertUnderline(spannable, isUnderline);
+    assertStrikethrough(spannable, isLinethrough);
+    assertUnderline(spannable, isUnderline);
+    assertBackground(spannable, backgroundColor);
+    assertForeground(spannable, color);
+    assertAlignment(spannable, alignment);
+  }
+
+  private void assertAbsoluteFontSize(Spannable spannable, int absoluteFontSize) {
+    AbsoluteSizeSpan[] absoluteSizeSpans = spannable.getSpans(0, spannable.length(),
+        AbsoluteSizeSpan.class);
+    assertEquals(1, absoluteSizeSpans.length);
+    assertEquals(absoluteFontSize, absoluteSizeSpans[0].getSize());
+  }
+
+  private void assertRelativeFontSize(Spannable spannable, float relativeFontSize) {
+    RelativeSizeSpan[] relativeSizeSpans = spannable.getSpans(0, spannable.length(),
+        RelativeSizeSpan.class);
+    assertEquals(1, relativeSizeSpans.length);
+    assertEquals(relativeFontSize, relativeSizeSpans[0].getSizeChange());
+  }
+
+  private void assertFont(Spannable spannable, String font) {
     TypefaceSpan[] typefaceSpans = spannable.getSpans(0, spannable.length(), TypefaceSpan.class);
     assertEquals(font, typefaceSpans[typefaceSpans.length - 1].getFamily());
+  }
 
+  private void assertStyle(Spannable spannable, int fontStyle) {
     StyleSpan[] styleSpans = spannable.getSpans(0, spannable.length(), StyleSpan.class);
     assertEquals(fontStyle, styleSpans[styleSpans.length - 1].getStyle());
+  }
 
+  private void assertUnderline(Spannable spannable, boolean isUnderline) {
     UnderlineSpan[] underlineSpans = spannable.getSpans(0, spannable.length(),
         UnderlineSpan.class);
     assertEquals(isUnderline ? "must be underlined" : "must not be underlined",
         isUnderline ? 1 : 0, underlineSpans.length);
+  }
 
+  private void assertStrikethrough(Spannable spannable, boolean isStrikethrough) {
     StrikethroughSpan[] striketroughSpans = spannable.getSpans(0, spannable.length(),
         StrikethroughSpan.class);
-    assertEquals(isLinethrough ? "must be strikethrough" : "must not be strikethrough",
-        isLinethrough ? 1 : 0, striketroughSpans.length);
+    assertEquals(isStrikethrough ? "must be strikethrough" : "must not be strikethrough",
+        isStrikethrough ? 1 : 0, striketroughSpans.length);
+  }
 
+  private void assertBackground(Spannable spannable, int backgroundColor) {
     BackgroundColorSpan[] backgroundColorSpans =
         spannable.getSpans(0, spannable.length(), BackgroundColorSpan.class);
     if (backgroundColor != 0) {
@@ -309,11 +436,16 @@ public final class TtmlParserTest extends InstrumentationTestCase {
     } else {
       assertEquals(0, backgroundColorSpans.length);
     }
+  }
 
+  private void assertForeground(Spannable spannable, int foregroundColor) {
     ForegroundColorSpan[] foregroundColorSpans =
         spannable.getSpans(0, spannable.length(), ForegroundColorSpan.class);
-    assertEquals(color, foregroundColorSpans[foregroundColorSpans.length - 1].getForegroundColor());
+    assertEquals(foregroundColor,
+        foregroundColorSpans[foregroundColorSpans.length - 1].getForegroundColor());
+  }
 
+  private void assertAlignment(Spannable spannable, Layout.Alignment alignment) {
     if (alignment != null) {
       AlignmentSpan.Standard[] alignmentSpans =
           spannable.getSpans(0, spannable.length(), AlignmentSpan.Standard.class);
@@ -334,7 +466,7 @@ public final class TtmlParserTest extends InstrumentationTestCase {
         }
       }
     }
-    return null;
+    throw new IllegalStateException("tag not found");
   }
 
   private TtmlSubtitle getSubtitle(String file) throws IOException {
diff --git a/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlStyleTest.java b/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlStyleTest.java
index c452f68327..12f6a9fe9a 100644
--- a/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlStyleTest.java
+++ b/library/src/androidTest/java/com/google/android/exoplayer/text/ttml/TtmlStyleTest.java
@@ -59,29 +59,6 @@ public final class TtmlStyleTest extends InstrumentationTestCase {
             BACKGROUND_COLOR, style.getBackgroundColor());
     }
 
-    public void testGetInheritableStyle() {
-        // same instance as long as everything can be inherited
-        assertSame(style, style.getInheritableStyle());
-        style.inherit(createAncestorStyle());
-        assertSame(style, style.getInheritableStyle());
-        // after setting a property which is not inheritable
-        // we expect the inheritable style to be another instance
-        style.setBackgroundColor(0);
-        TtmlStyle inheritableStyle = style.getInheritableStyle();
-        assertNotSame(style, inheritableStyle);
-        // and subsequent call give always the same instance
-        assertSame(inheritableStyle, style.getInheritableStyle());
-
-        boolean exceptionThrown = false;
-        try {
-          // setting properties after calling getInheritableStyle gives an exception
-          style.setItalic(true);
-        } catch (IllegalStateException e) {
-          exceptionThrown = true;
-        }
-        assertTrue(exceptionThrown);
-    }
-
     private TtmlStyle createAncestorStyle() {
         TtmlStyle ancestor = new TtmlStyle();
         ancestor.setId(ID);
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 87670e7f8b..0009913bdc 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
@@ -73,6 +73,8 @@ public final class TtmlParser implements SubtitleParser {
           + "(?:(\\.[0-9]+)|:([0-9][0-9])(?:\\.([0-9]+))?)?$");
   private static final Pattern OFFSET_TIME =
       Pattern.compile("^([0-9]+(?:\\.[0-9]+)?)(h|m|s|ms|f|t)$");
+  private static final Pattern FONT_SIZE =
+      Pattern.compile("^(([0-9]*.)?[0-9]+)(px|em|%)$");
 
   // TODO: read and apply the following attributes if specified.
   private static final int DEFAULT_FRAMERATE = 30;
@@ -223,7 +225,12 @@ public final class TtmlParser implements SubtitleParser {
           style = createIfNull(style).setFontFamily(attributeValue);
           break;
         case TtmlNode.ATTR_TTS_FONT_SIZE:
-          // TODO: handle size
+          try {
+            style = createIfNull(style);
+            parseFontSize(attributeValue, style);
+          } catch (ParserException e) {
+            Log.w(TAG, "failed parsing fontSize value: '" + attributeValue + "'");
+          }
           break;
         case TtmlNode.ATTR_TTS_FONT_WEIGHT:
           style = createIfNull(style).setBold(
@@ -355,6 +362,40 @@ public final class TtmlParser implements SubtitleParser {
     return false;
   }
 
+  private static void parseFontSize(String expression, TtmlStyle out) throws ParserException {
+    String[] expressions = expression.split("\\s+");
+    Matcher matcher;
+    if (expressions.length == 1) {
+      matcher = FONT_SIZE.matcher(expression);
+    } else if (expressions.length == 2){
+      matcher = FONT_SIZE.matcher(expressions[1]);
+      Log.w(TAG, "multiple values in fontSize attribute. Picking the second "
+          + "value for vertical font size and ignoring the first.");
+    } else {
+      throw new ParserException();
+    }
+
+    if (matcher.matches()) {
+      String unit = matcher.group(3);
+      switch (unit) {
+        case "px":
+          out.setFontSizeUnit(TtmlStyle.FONT_SIZE_UNIT_PIXEL);
+          break;
+        case "em":
+          out.setFontSizeUnit(TtmlStyle.FONT_SIZE_UNIT_EM);
+          break;
+        case "%":
+          out.setFontSizeUnit(TtmlStyle.FONT_SIZE_UNIT_PERCENT);
+          break;
+        default:
+          throw new ParserException();
+      }
+      out.setFontSize(Float.valueOf(matcher.group(1)));
+    } else {
+      throw new ParserException();
+    }
+  }
+
   /**
    * Parses a time expression, returning the parsed timestamp.
    * <p>
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
index 638e47d276..63b6cc8886 100644
--- 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
@@ -18,9 +18,11 @@ package com.google.android.exoplayer.text.ttml;
 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;
 import android.text.style.StrikethroughSpan;
 import android.text.style.StyleSpan;
 import android.text.style.TypefaceSpan;
@@ -101,6 +103,22 @@ import java.util.Map;
       builder.setSpan(new AlignmentSpan.Standard(style.getTextAlign()), start, end,
           Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
     }
+    if (style.getFontSizeUnit() != TtmlStyle.UNSPECIFIED) {
+      switch (style.getFontSizeUnit()) {
+        case TtmlStyle.FONT_SIZE_UNIT_PIXEL:
+          builder.setSpan(new AbsoluteSizeSpan((int) style.getFontSize(), true), start, end,
+              Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+          break;
+        case TtmlStyle.FONT_SIZE_UNIT_EM:
+          builder.setSpan(new RelativeSizeSpan(style.getFontSize()), start, end,
+              Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+          break;
+        case TtmlStyle.FONT_SIZE_UNIT_PERCENT:
+          builder.setSpan(new RelativeSizeSpan(style.getFontSize() / 100), start, end,
+              Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+          break;
+      }
+    }
   }
 
   /**
diff --git a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlStyle.java b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlStyle.java
index 7bb2891d0e..4cb5f95a86 100644
--- a/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlStyle.java
+++ b/library/src/main/java/com/google/android/exoplayer/text/ttml/TtmlStyle.java
@@ -23,7 +23,7 @@ import android.text.Layout;
 /**
  * Style object of a <code>TtmlNode</code>
  */
-public final class TtmlStyle {
+/* package */ final class TtmlStyle {
 
   public static final short UNSPECIFIED = -1;
 
@@ -32,6 +32,10 @@ public final class TtmlStyle {
   public static final short STYLE_ITALIC = Typeface.ITALIC;
   public static final short STYLE_BOLD_ITALIC = Typeface.BOLD_ITALIC;
 
+  public static final short FONT_SIZE_UNIT_PIXEL = 1;
+  public static final short FONT_SIZE_UNIT_EM = 2;
+  public static final short FONT_SIZE_UNIT_PERCENT = 3;
+
   private static final short OFF = 0;
   private static final short ON = 1;
 
@@ -44,6 +48,8 @@ public final class TtmlStyle {
   private short underline = UNSPECIFIED;
   private short bold = UNSPECIFIED;
   private short italic = UNSPECIFIED;
+  private short fontSizeUnit = UNSPECIFIED;
+  private float fontSize;
   private String id;
   private TtmlStyle inheritableStyle;
   private Layout.Alignment textAlign;
@@ -139,19 +145,6 @@ public final class TtmlStyle {
     return this;
   }
 
-  public TtmlStyle getInheritableStyle() {
-    if (isFullyInheritable()) {
-      return this;
-    } else if (inheritableStyle == null) {
-      inheritableStyle = new TtmlStyle().inherit(this);
-    }
-    return inheritableStyle;
-  }
-
-  private boolean isFullyInheritable() {
-    return !backgroundColorSpecified;
-  }
-
   /**
    * Inherits from an ancestor style. Properties like <i>tts:backgroundColor</i> which
    * are not inheritable are not inherited as well as properties which are already set locally
@@ -196,6 +189,10 @@ public final class TtmlStyle {
       if (textAlign == null) {
         textAlign = ancestor.textAlign;
       }
+      if (fontSizeUnit == UNSPECIFIED) {
+        fontSizeUnit = ancestor.fontSizeUnit;
+        fontSize = ancestor.fontSize;
+      }
       // attributes not inherited as of http://www.w3.org/TR/ttml1/
       if (chaining && !backgroundColorSpecified && ancestor.backgroundColorSpecified) {
         setBackgroundColor(ancestor.backgroundColor);
@@ -221,4 +218,23 @@ public final class TtmlStyle {
     this.textAlign = textAlign;
     return this;
   }
+
+  public TtmlStyle setFontSize(float fontSize) {
+    this.fontSize = fontSize;
+    return this;
+  }
+
+  public TtmlStyle setFontSizeUnit(short unit) {
+    this.fontSizeUnit = unit;
+    return this;
+  }
+
+  public short getFontSizeUnit() {
+    return fontSizeUnit;
+  }
+
+  public float getFontSize() {
+    return fontSize;
+  }
+
 }
