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Support Webvtt subtitles class colors #4178

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merged 4 commits into from
Feb 17, 2020
Merged

Support Webvtt subtitles class colors #4178

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117239a
Apply ColorSpan if subtitle cue startTag contains color class
danybony Apr 24, 2018
e99a7f6
Merge branch 'dev-v2' into subtitle_color_in_cue_class
danybony Feb 12, 2020
fc5dbfe
Add default colors list in WebvttCueParser for text foreground class …
danybony Feb 13, 2020
987939d
Add suport for text background color classes
danybony Feb 13, 2020
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13 changes: 13 additions & 0 deletions library/core/src/main/java/com/google/android/exoplayer2/text/webvtt/WebvttCueParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@
import com.google.android.exoplayer2.text.span.HorizontalTextInVerticalContextSpan;
import com.google.android.exoplayer2.text.span.RubySpan;
import com.google.android.exoplayer2.util.Assertions;
import com.google.android.exoplayer2.util.ColorParser;
import com.google.android.exoplayer2.util.Log;
import com.google.android.exoplayer2.util.ParsableByteArray;
import com.google.android.exoplayer2.util.Util;
Expand Down Expand Up @@ -514,6 +515,8 @@ private static void applySpansForTag(
text.setSpan(new UnderlineSpan(), start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
break;
case TAG_CLASS:
applySupportedClasses(text, startTag.classes, start, end);
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Can you add some tests to WebvttCueParserTest for this?

break;
case TAG_LANG:
case TAG_VOICE:
case "": // Case of the "whole cue" virtual tag.
Expand All @@ -529,6 +532,16 @@ private static void applySpansForTag(
}
}

private static void applySupportedClasses(SpannableStringBuilder text, String[] classes,
int start, int end) {
for (String className : classes) {
if (ColorParser.isNamedColor(className)) {
int color = ColorParser.parseCssColor(className);
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This is neat code re-use, but because the WebVTT list is so much shorter than the list of CSS colors I think it would be clearer to explicitly list the WebVTT default colors. Otherwise if someone defines a custom class called papayawhip in their style section that maybe has nothing to do with that color, we'll color the cue anyway (which is not in-line with the WebVTT spec).

So I think a private static final Map<String, Integer> DEFAULT_COLORS inside WebvttCueParser would be the best approach here. You'll probably have to populate it in a static initializer block the same as in ColorParser.

That will also make adding background color support less 'different' - we can just add a DEFAULT_BACKGROUND_COLORS map alongside. If you have the time/inclination, feel free to also add that in this same PR! :)

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Sounds good, I'll take a look and update this soon

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Updated the strategy by adding the two maps (adds support for background too) in WebvttCueParser and removing the dependency from the color parser.
Added relevant tests too

text.setSpan(new ForegroundColorSpan(color), start, end, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
}
}
}

private static void applyStyleToText(SpannableStringBuilder spannedText, WebvttCssStyle style,
int start, int end) {
if (style == null) {
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4 changes: 4 additions & 0 deletions library/core/src/main/java/com/google/android/exoplayer2/util/ColorParser.java
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Expand Up @@ -43,6 +43,10 @@ public final class ColorParser {

private static final Map<String, Integer> COLOR_MAP;

public static boolean isNamedColor(String expression) {
return COLOR_MAP.containsKey(expression);
}

/**
* Parses a TTML color expression.
*
Expand Down