Provide more flexibility for setting caption font size.

- Respect any padding set on SubtitleLayout.
- Allow specification of absolute, fractional and fractional-ignoring-padding
  text sizes.

demo/src/main/java/com/google/android/exoplayer/demo/PlayerActivity.java

@@ -562,17 +562,17 @@ public class PlayerActivity extends Activity implements SurfaceHolder.Callback,
   }
 
   private void configureSubtitleView() {
-    CaptionStyleCompat captionStyle;
+    CaptionStyleCompat style;
-    float captionFontScale;
+    float fontScale;
     if (Util.SDK_INT >= 19) {
-      captionStyle = getUserCaptionStyleV19();
+      style = getUserCaptionStyleV19();
-      captionFontScale = getUserCaptionFontScaleV19();
+      fontScale = getUserCaptionFontScaleV19();
     } else {
-      captionStyle = CaptionStyleCompat.DEFAULT;
+      style = CaptionStyleCompat.DEFAULT;
-      captionFontScale = 1.0f;
+      fontScale = 1.0f;
     }
-    subtitleLayout.setStyle(captionStyle);
+    subtitleLayout.setStyle(style);
-    subtitleLayout.setFontScale(captionFontScale);
+    subtitleLayout.setFractionalTextSize(SubtitleLayout.DEFAULT_TEXT_SIZE_FRACTION * fontScale);
   }
 
   @TargetApi(19)

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

@@ -45,12 +45,6 @@ import android.util.Log;
    */
   private static final float INNER_PADDING_RATIO = 0.125f;
 
-  /**
-   * Use the same line height ratio as WebVtt to match the display with the preview.
-   * WebVtt specifies line height as 5.3% of the viewport height.
-   */
-  private static final float LINE_HEIGHT_FRACTION = 0.0533f;
-
   /**
    * Temporary rectangle used for computing line bounds.
    */
@@ -77,7 +71,7 @@ import android.util.Log;
   private int windowColor;
   private int edgeColor;
   private int edgeType;
-  private float fontScale;
+  private float textSizePx;
   private float bottomPaddingFraction;
   private int parentLeft;
   private int parentTop;
@@ -124,7 +118,7 @@ import android.util.Log;
    * @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 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
    * @param canvas The canvas into which to draw.
@@ -133,7 +127,7 @@ 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, boolean applyEmbeddedStyles, CaptionStyleCompat style, float fontScale,
+  public void draw(Cue cue, boolean applyEmbeddedStyles, CaptionStyleCompat style, float textSizePx,
       float bottomPaddingFraction, Canvas canvas, int cueBoxLeft, int cueBoxTop, int cueBoxRight,
       int cueBoxBottom) {
     CharSequence cueText = cue.text;
@@ -155,7 +149,7 @@ import android.util.Log;
         && this.edgeType == style.edgeType
         && this.edgeColor == style.edgeColor
         && Util.areEqual(this.textPaint.getTypeface(), style.typeface)
-        && this.fontScale == fontScale
+        && this.textSizePx == textSizePx
         && this.bottomPaddingFraction == bottomPaddingFraction
         && this.parentLeft == cueBoxLeft
         && this.parentTop == cueBoxTop
@@ -176,7 +170,7 @@ import android.util.Log;
     this.edgeType = style.edgeType;
     this.edgeColor = style.edgeColor;
     this.textPaint.setTypeface(style.typeface);
-    this.fontScale = fontScale;
+    this.textSizePx = textSizePx;
     this.bottomPaddingFraction = bottomPaddingFraction;
     this.parentLeft = cueBoxLeft;
     this.parentTop = cueBoxTop;
@@ -186,9 +180,8 @@ import android.util.Log;
     int parentWidth = parentRight - parentLeft;
     int parentHeight = parentBottom - parentTop;
 
-    float textSize = LINE_HEIGHT_FRACTION * parentHeight * fontScale;
+    textPaint.setTextSize(textSizePx);
-    textPaint.setTextSize(textSize);
+    int textPaddingX = (int) (textSizePx * INNER_PADDING_RATIO + 0.5f);
-    int textPaddingX = (int) (textSize * INNER_PADDING_RATIO + 0.5f);
     int availableWidth = parentWidth - textPaddingX * 2;
     if (availableWidth <= 0) {
       Log.w(TAG, "Skipped drawing subtitle cue (insufficient space)");
@@ -207,12 +200,8 @@ import android.util.Log;
     }
     textWidth += textPaddingX * 2;
 
-    int textLeft = (parentWidth - textWidth) / 2;
+    int textLeft;
-    int textRight = textLeft + textWidth;
+    int textRight;
-    int textTop = parentBottom - textHeight
-        - (int) (parentHeight * bottomPaddingFraction);
-    int textBottom = textTop + textHeight;
-
     if (cue.position != Cue.UNSET_VALUE) {
       if (cue.alignment == Alignment.ALIGN_OPPOSITE) {
         textRight = (parentWidth * cue.position) / 100 + parentLeft;
@@ -221,7 +210,13 @@ import android.util.Log;
         textLeft = (parentWidth * cue.position) / 100 + parentLeft;
         textRight = Math.min(textLeft + textWidth, parentRight);
       }
+    } else {
+      textLeft = (parentWidth - textWidth) / 2;
+      textRight = textLeft + textWidth;
     }
+
+    int textTop;
+    int textBottom;
     if (cue.line != Cue.UNSET_VALUE) {
       textTop = (parentHeight * cue.line) / 100 + parentTop;
       textBottom = textTop + textHeight;
@@ -229,7 +224,11 @@ import android.util.Log;
         textTop = parentBottom - textHeight;
         textBottom = parentBottom;
       }
+    } else {
+      textTop = parentBottom - textHeight - (int) (parentHeight * bottomPaddingFraction);
+      textBottom = textTop + textHeight;
     }
+
     textWidth = textRight - textLeft;
 
     // Update the derived drawing variables.

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

@@ -16,8 +16,10 @@
 package com.google.android.exoplayer.text;
 
 import android.content.Context;
+import android.content.res.Resources;
 import android.graphics.Canvas;
 import android.util.AttributeSet;
+import android.util.TypedValue;
 import android.view.View;
 
 import java.util.ArrayList;
@@ -28,16 +30,30 @@ import java.util.List;
  */
 public final class SubtitleLayout extends View {
 
+  /**
+   * The default fractional text size.
+   *
+   * @see #setFractionalTextSize(float, boolean)
+   */
+  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
    * fraction of the viewport height.
+   *
+   * @see #setBottomPaddingFraction(float)
    */
   public static final float DEFAULT_BOTTOM_PADDING_FRACTION = 0.08f;
 
+  private static final int FRACTIONAL = 0;
+  private static final int FRACTIONAL_IGNORE_PADDING = 1;
+  private static final int ABSOLUTE = 2;
+
   private final List<CuePainter> painters;
 
   private List<Cue> cues;
-  private float fontScale;
+  private int textSizeType;
+  private float textSize;
   private boolean applyEmbeddedStyles;
   private CaptionStyleCompat style;
   private float bottomPaddingFraction;
@@ -49,7 +65,8 @@ public final class SubtitleLayout extends View {
   public SubtitleLayout(Context context, AttributeSet attrs) {
     super(context, attrs);
     painters = new ArrayList<>();
-    fontScale = 1;
+    textSizeType = FRACTIONAL;
+    textSize = DEFAULT_TEXT_SIZE_FRACTION;
     applyEmbeddedStyles = true;
     style = CaptionStyleCompat.DEFAULT;
     bottomPaddingFraction = DEFAULT_BOTTOM_PADDING_FRACTION;
@@ -75,15 +92,55 @@ public final class SubtitleLayout extends View {
   }
 
   /**
-   * Sets the scale of the font.
+   * Set the text size to a given unit and value.
+   * <p>
+   * See {@link TypedValue} for the possible dimension units.
    *
-   * @param fontScale The scale of the font.
+   * @param unit The desired dimension unit.
+   * @param size The desired size in the given units.
    */
-  public void setFontScale(float fontScale) {
+  public void setFixedTextSize(int unit, float size) {
-    if (this.fontScale == fontScale) {
+    Context context = getContext();
+    Resources resources;
+    if (context == null) {
+      resources = Resources.getSystem();
+    } else {
+      resources = context.getResources();
+    }
+    setTextSize(ABSOLUTE, TypedValue.applyDimension(unit, size, resources.getDisplayMetrics()));
+  }
+
+  /**
+   * Sets the text size to be a fraction of the view's remaining height after its top and bottom
+   * padding have been subtracted.
+   * <p>
+   * Equivalent to {@code #setFractionalTextSize(fractionOfHeight, false)}.
+   *
+   * @param fractionOfHeight A fraction between 0 and 1.
+   */
+  public void setFractionalTextSize(float fractionOfHeight) {
+    setFractionalTextSize(fractionOfHeight, false);
+  }
+
+  /**
+   * Sets the text size to be a fraction of the height of this view.
+   *
+   * @param fractionOfHeight A fraction between 0 and 1.
+   * @param ignorePadding Set to true if {@code fractionOfHeight} should be interpreted as a
+   *     fraction of this view's height ignoring any top and bottom padding. Set to false if
+   *     {@code fractionOfHeight} should be interpreted as a fraction of this view's remaining
+   *     height after the top and bottom padding has been subtracted.
+   */
+  public void setFractionalTextSize(float fractionOfHeight, boolean ignorePadding) {
+    setTextSize(ignorePadding ? FRACTIONAL_IGNORE_PADDING : FRACTIONAL, fractionOfHeight);
+  }
+
+  private void setTextSize(int textSizeType, float textSize) {
+    if (this.textSizeType == textSizeType && this.textSize == textSize) {
       return;
     }
-    this.fontScale = fontScale;
+    this.textSizeType = textSizeType;
+    this.textSize = textSize;
     // Invalidate to trigger drawing.
     invalidate();
   }
@@ -118,7 +175,10 @@ public final class SubtitleLayout extends View {
 
   /**
    * Sets the bottom padding fraction to apply when {@link Cue#line} is {@link Cue#UNSET_VALUE},
-   * as a fraction of the viewport height.
+   * as a fraction of the view's remaining height after its top and bottom padding have been
+   * subtracted.
+   * <p>
+   * Note that this padding is applied in addition to any standard view padding.
    *
    * @param bottomPaddingFraction The bottom padding fraction.
    */
@@ -134,9 +194,29 @@ public final class SubtitleLayout extends View {
   @Override
   public void dispatchDraw(Canvas canvas) {
     int cueCount = (cues == null) ? 0 : cues.size();
+    int rawTop = getTop();
+    int rawBottom = getBottom();
+
+    // Calculate the bounds after padding is taken into account.
+    int left = getLeft() + getPaddingLeft();
+    int top = rawTop + getPaddingTop();
+    int right = getRight() + getPaddingRight();
+    int bottom = rawBottom - getPaddingBottom();
+    if (bottom <= top || right <= left) {
+      // No space to draw subtitles.
+      return;
+    }
+
+    float textSizePx = textSizeType == ABSOLUTE ? textSize
+        : textSize * (textSizeType == FRACTIONAL ? (bottom - top) : (rawBottom - rawTop));
+    if (textSizePx <= 0) {
+      // Text has no height.
+      return;
+    }
+
     for (int i = 0; i < cueCount; i++) {
-      painters.get(i).draw(cues.get(i), applyEmbeddedStyles, style, fontScale,
+      painters.get(i).draw(cues.get(i), applyEmbeddedStyles, style, textSizePx,
-          bottomPaddingFraction, canvas, getLeft(), getTop(), getRight(), getBottom());
+          bottomPaddingFraction, canvas, left, top, right, bottom);
     }
   }