Further improve WebVTT parser according to WebVTT spec

library/src/androidTest/assets/webvtt/live_typical

-WEBVTT
-
-00:00.000 --> 00:01.234
-This is the first subtitle.
-
-00:02.345 --> 00:03.456
-This is the second subtitle.

library/src/androidTest/assets/webvtt/typical_with_comments

@@ -8,7 +8,9 @@ with multiple lines
 00:00.000 --> 00:01.234
 This is the first subtitle.
 
-NOTE Single line comment
+NOTE Single line comment with a space
+
+NOTE	Single line comment with a tab
 
 2
 00:02.345 --> 00:03.456

library/src/androidTest/assets/webvtt/typical_with_metadata → library/src/androidTest/assets/webvtt/with_positioning

@@ -16,7 +16,13 @@ NOTE Line as percentage and line alignment
 00:04.000 --> 00:05.000 line:45%,end align:middle size:35%
 This is the third subtitle.
 
-NOTE Line as absolute negative number and without line alignment
+NOTE Line as absolute negative number and without line alignment.
+
+00:06.000 --> 00:07.000 line:-10 align:middle
+This is the fourth subtitle.
+
+NOTE The positioning alignment should be inherited from align.
+
+00:07.000 --> 00:08.000 position:10% align:end size:10%
+This is the fifth subtitle.
 
-00:06.000 --> 00:07.000 line:-10 align:middle size:35%
-This is the forth subtitle.

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

@@ -23,30 +23,117 @@ import android.text.Layout.Alignment;
 public class Cue {
 
   /**
-   * Used by some methods to indicate that no value is set.
+   * An unset position or width.
    */
-  public static final int UNSET_VALUE = -1;
+  public static final float DIMEN_UNSET = Float.MIN_VALUE;
+  /**
+   * An unset anchor or line type value.
+   */
+  public static final int TYPE_UNSET = Integer.MIN_VALUE;
+  /**
+   * Anchors the left (for horizontal positions) or top (for vertical positions) edge of the cue
+   * box.
+   */
+  public static final int ANCHOR_TYPE_START = 0;
+  /**
+   * Anchors the middle of the cue box.
+   */
+  public static final int ANCHOR_TYPE_MIDDLE = 1;
+  /**
+   * Anchors the right (for horizontal positions) or bottom (for vertical positions) edge of the cue
+   * box.
+   */
+  public static final int ANCHOR_TYPE_END = 2;
+  /**
+   * Value for {@link #lineType} when {@link #line} is a fractional position.
+   */
+  public static final int LINE_TYPE_FRACTION = 0;
+  /**
+   * Value for {@link #lineType} when {@link #line} is a line number.
+   */
+  public static final int LINE_TYPE_NUMBER = 1;
 
+  /**
+   * The cue text. Note the {@link CharSequence} may be decorated with styling spans.
+   */
   public final CharSequence text;
-
-  public final int line;
-  public final int position;
-  public final Alignment alignment;
-  public final int size;
+  /**
+   * The alignment of the cue text within the cue box.
+   */
+  public final Alignment textAlignment;
+  /**
+   * The position of the {@link #lineAnchor} of the cue box within the viewport in the direction
+   * orthogonal to the writing direction, or {@link #DIMEN_UNSET}. When set, the interpretation of
+   * the value depends on the value of {@link #lineType}.
+   * <p>
+   * For horizontal text and {@link #lineType} equal to {@link #LINE_TYPE_FRACTION}, this is the
+   * fractional vertical position relative to the top of the viewport.
+   */
+  public final float line;
+  /**
+   * The type of the {@link #line} value.
+   * <p>
+   * {@link #LINE_TYPE_FRACTION} indicates that {@link #line} is a fractional position within the
+   * viewport.
+   * <p>
+   * {@link #LINE_TYPE_NUMBER} indicates that {@link #line} is a line number, where the size of each
+   * line is taken to be the size of the first line of the cue. When {@link #line} is greater than
+   * or equal to 0, lines count from the start of the viewport (the first line is numbered 0). When
+   * {@link #line} is negative, lines count from the end of the viewport (the last line is numbered
+   * -1). For horizontal text the size of the first line of the cue is its height, and the start
+   * and end of the viewport are the top and bottom respectively.
+   */
+  public final int lineType;
+  /**
+   * The cue box anchor positioned by {@link #line}. One of {@link #ANCHOR_TYPE_START},
+   * {@link #ANCHOR_TYPE_MIDDLE}, {@link #ANCHOR_TYPE_END} and {@link #TYPE_UNSET}.
+   * <p>
+   * For the normal case of horizontal text, {@link #ANCHOR_TYPE_START}, {@link #ANCHOR_TYPE_MIDDLE}
+   * and {@link #ANCHOR_TYPE_END} correspond to the top, middle and bottom of the cue box
+   * respectively.
+   */
+  public final int lineAnchor;
+  /**
+   * The fractional position of the {@link #positionAnchor} of the cue box within the viewport in
+   * the direction orthogonal to {@link #line}, or {@link #DIMEN_UNSET}.
+   * <p>
+   * For horizontal text, this is the horizontal position relative to the left of the viewport. Note
+   * that positioning is relative to the left of the viewport even in the case of right-to-left
+   * text.
+   */
+  public final float position;
+  /**
+   * The cue box anchor positioned by {@link #position}. One of {@link #ANCHOR_TYPE_START},
+   * {@link #ANCHOR_TYPE_MIDDLE}, {@link #ANCHOR_TYPE_END} and {@link #TYPE_UNSET}.
+   * <p>
+   * For the normal case of horizontal text, {@link #ANCHOR_TYPE_START}, {@link #ANCHOR_TYPE_MIDDLE}
+   * and {@link #ANCHOR_TYPE_END} correspond to the left, middle and right of the cue box
+   * respectively.
+   */
+  public final int positionAnchor;
+  /**
+   * The size of the cue box in the writing direction specified as a fraction of the viewport size
+   * in that direction, or {@link #DIMEN_UNSET}.
+   */
+  public final float size;
 
   public Cue() {
     this(null);
   }
 
   public Cue(CharSequence text) {
-    this(text, UNSET_VALUE, UNSET_VALUE, null, UNSET_VALUE);
+    this(text, null, DIMEN_UNSET, TYPE_UNSET, TYPE_UNSET, DIMEN_UNSET, TYPE_UNSET, DIMEN_UNSET);
   }
 
-  public Cue(CharSequence text, int line, int position, Alignment alignment, int size) {
+  public Cue(CharSequence text, Alignment textAlignment, float line, int lineType,
+      int lineAnchor, float position, int positionAnchor, float size) {
     this.text = text;
+    this.textAlignment = textAlignment;
     this.line = line;
+    this.lineType = lineType;
+    this.lineAnchor = lineAnchor;
     this.position = position;
-    this.alignment = alignment;
+    this.positionAnchor = positionAnchor;
     this.size = size;
   }
 

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

@@ -63,8 +63,13 @@ import android.util.Log;
 
   // Previous input variables.
   private CharSequence cueText;
-  private int cuePosition;
-  private Alignment cueAlignment;
+  private Alignment cueTextAlignment;
+  private float cueLine;
+  private int cueLineType;
+  private int cueLineAnchor;
+  private float cuePosition;
+  private int cuePositionAnchor;
+  private float cueSize;
   private boolean applyEmbeddedStyles;
   private int foregroundColor;
   private int backgroundColor;
@@ -120,7 +125,7 @@ import android.util.Log;
    * @param style The style to use when drawing the cue text.
    * @param textSizePx The text size to use when drawing the cue text, in pixels.
    * @param bottomPaddingFraction The bottom padding fraction to apply when {@link Cue#line} is
-   *     {@link Cue#UNSET_VALUE}, as a fraction of the viewport height
+   *     {@link Cue#DIMEN_UNSET}, as a fraction of the viewport height
    * @param canvas The canvas into which to draw.
    * @param cueBoxLeft The left position of the enclosing cue box.
    * @param cueBoxTop The top position of the enclosing cue box.
@@ -140,8 +145,13 @@ import android.util.Log;
       cueText = cueText.toString();
     }
     if (areCharSequencesEqual(this.cueText, cueText)
+        && Util.areEqual(this.cueTextAlignment, cue.textAlignment)
+        && this.cueLine == cue.line
+        && this.cueLineType == cue.lineType
+        && Util.areEqual(this.cueLineAnchor, cue.lineAnchor)
         && this.cuePosition == cue.position
-        && Util.areEqual(this.cueAlignment, cue.alignment)
+        && Util.areEqual(this.cuePositionAnchor, cue.positionAnchor)
+        && this.cueSize == cue.size
         && this.applyEmbeddedStyles == applyEmbeddedStyles
         && this.foregroundColor == style.foregroundColor
         && this.backgroundColor == style.backgroundColor
@@ -161,8 +171,13 @@ import android.util.Log;
     }
 
     this.cueText = cueText;
+    this.cueTextAlignment = cue.textAlignment;
+    this.cueLine = cue.line;
+    this.cueLineType = cue.lineType;
+    this.cueLineAnchor = cue.lineAnchor;
     this.cuePosition = cue.position;
-    this.cueAlignment = cue.alignment;
+    this.cuePositionAnchor = cue.positionAnchor;
+    this.cueSize = cue.size;
     this.applyEmbeddedStyles = applyEmbeddedStyles;
     this.foregroundColor = style.foregroundColor;
     this.backgroundColor = style.backgroundColor;
@@ -182,16 +197,19 @@ import android.util.Log;
 
     textPaint.setTextSize(textSizePx);
     int textPaddingX = (int) (textSizePx * INNER_PADDING_RATIO + 0.5f);
+
     int availableWidth = parentWidth - textPaddingX * 2;
+    if (cueSize != Cue.DIMEN_UNSET) {
+      availableWidth = (int) (availableWidth * cueSize);
+    }
     if (availableWidth <= 0) {
       Log.w(TAG, "Skipped drawing subtitle cue (insufficient space)");
       return;
     }
 
-    Alignment layoutAlignment = cueAlignment == null ? Alignment.ALIGN_CENTER : cueAlignment;
-    textLayout = new StaticLayout(cueText, textPaint, availableWidth, layoutAlignment, spacingMult,
+    Alignment textAlignment = cueTextAlignment == null ? Alignment.ALIGN_CENTER : cueTextAlignment;
+    textLayout = new StaticLayout(cueText, textPaint, availableWidth, textAlignment, spacingMult,
         spacingAdd, true);
-
     int textHeight = textLayout.getHeight();
     int textWidth = 0;
     int lineCount = textLayout.getLineCount();
@@ -202,14 +220,13 @@ import android.util.Log;
 
     int textLeft;
     int textRight;
-    if (cue.position != Cue.UNSET_VALUE) {
-      if (cue.alignment == Alignment.ALIGN_OPPOSITE) {
-        textRight = (parentWidth * cue.position) / 100 + parentLeft;
-        textLeft = Math.max(textRight - textWidth, parentLeft);
-      } else {
-        textLeft = (parentWidth * cue.position) / 100 + parentLeft;
-        textRight = Math.min(textLeft + textWidth, parentRight);
-      }
+    if (cuePosition != Cue.DIMEN_UNSET) {
+      int anchorPosition = Math.round(parentWidth * cuePosition) + parentLeft;
+      textLeft = cuePositionAnchor == Cue.ANCHOR_TYPE_END ? anchorPosition - textWidth
+          : cuePositionAnchor == Cue.ANCHOR_TYPE_MIDDLE ? (anchorPosition * 2 - textWidth) / 2
+          : anchorPosition;
+      textLeft = Math.max(textLeft, parentLeft);
+      textRight = Math.min(textLeft + textWidth, parentRight);
     } else {
       textLeft = (parentWidth - textWidth) / 2;
       textRight = textLeft + textWidth;
@@ -217,12 +234,29 @@ import android.util.Log;
 
     int textTop;
     int textBottom;
-    if (cue.line != Cue.UNSET_VALUE) {
-      textTop = (parentHeight * cue.line) / 100 + parentTop;
+    if (cueLine != Cue.DIMEN_UNSET) {
+      int anchorPosition;
+      if (cueLineType == Cue.LINE_TYPE_FRACTION) {
+        anchorPosition = Math.round(parentHeight * cueLine) + parentTop;
+      } else {
+        // cueLineType == Cue.LINE_TYPE_NUMBER
+        int firstLineHeight = textLayout.getLineBottom(0) - textLayout.getLineTop(0);
+        if (cueLine >= 0) {
+          anchorPosition = Math.round(cueLine * firstLineHeight) + parentTop;
+        } else {
+          anchorPosition = Math.round(cueLine * firstLineHeight) + parentBottom;
+        }
+      }
+      textTop = cueLineAnchor == Cue.ANCHOR_TYPE_END ? anchorPosition - textHeight
+          : cueLineAnchor == Cue.ANCHOR_TYPE_MIDDLE ? (anchorPosition * 2 - textHeight) / 2
+          : anchorPosition;
       textBottom = textTop + textHeight;
       if (textBottom > parentBottom) {
         textTop = parentBottom - textHeight;
         textBottom = parentBottom;
+      } else if (textTop < parentTop) {
+        textTop = parentTop;
+        textBottom = parentTop + textHeight;
       }
     } else {
       textTop = parentBottom - textHeight - (int) (parentHeight * bottomPaddingFraction);
@@ -232,7 +266,7 @@ import android.util.Log;
     textWidth = textRight - textLeft;
 
     // Update the derived drawing variables.
-    this.textLayout = new StaticLayout(cueText, textPaint, textWidth, layoutAlignment, spacingMult,
+    this.textLayout = new StaticLayout(cueText, textPaint, textWidth, textAlignment, spacingMult,
         spacingAdd, true);
     this.textLeft = textLeft;
     this.textTop = textTop;

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

@@ -38,7 +38,7 @@ public final class SubtitleLayout extends View {
   public static final float DEFAULT_TEXT_SIZE_FRACTION = 0.0533f;
 
   /**
-   * The default bottom padding to apply when {@link Cue#line} is {@link Cue#UNSET_VALUE}, as a
+   * The default bottom padding to apply when {@link Cue#line} is {@link Cue#DIMEN_UNSET}, as a
    * fraction of the viewport height.
    *
    * @see #setBottomPaddingFraction(float)
@@ -174,7 +174,7 @@ public final class SubtitleLayout extends View {
   }
 
   /**
-   * Sets the bottom padding fraction to apply when {@link Cue#line} is {@link Cue#UNSET_VALUE},
+   * Sets the bottom padding fraction to apply when {@link Cue#line} is {@link Cue#DIMEN_UNSET},
    * as a fraction of the view's remaining height after its top and bottom padding have been
    * subtracted.
    * <p>

library/src/main/java/com/google/android/exoplayer/text/webvtt/WebvttCue.java

@@ -28,16 +28,17 @@ import android.text.Layout.Alignment;
   public final long endTime;
 
   public WebvttCue(CharSequence text) {
-    this(Cue.UNSET_VALUE, Cue.UNSET_VALUE, text);
+    this(0, 0, text);
   }
 
   public WebvttCue(long startTime, long endTime, CharSequence text) {
-    this(startTime, endTime, text, Cue.UNSET_VALUE, Cue.UNSET_VALUE, null, Cue.UNSET_VALUE);
+    this(startTime, endTime, text, null, Cue.DIMEN_UNSET, Cue.TYPE_UNSET, Cue.TYPE_UNSET,
+        Cue.DIMEN_UNSET, Cue.TYPE_UNSET, Cue.DIMEN_UNSET);
   }
 
-  public WebvttCue(long startTime, long endTime, CharSequence text, int line, int position,
-      Alignment alignment, int size) {
-    super(text, line, position, alignment, size);
+  public WebvttCue(long startTime, long endTime, CharSequence text, Alignment textAlignment,
+      float line, int lineType, int lineAnchor, float position, int positionAnchor, float width) {
+    super(text, textAlignment, line, lineType, lineAnchor, position, positionAnchor, width);
     this.startTime = startTime;
     this.endTime = endTime;
   }
@@ -49,7 +50,7 @@ import android.text.Layout.Alignment;
    * @return True if this cue should be placed in the default position; false otherwise.
    */
   public boolean isNormalCue() {
-    return (line == UNSET_VALUE && position == UNSET_VALUE);
+    return (line == DIMEN_UNSET && position == DIMEN_UNSET);
   }
 
 }