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Fix bug in TTML inherited text alignment

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Fix bug where child does not correctly inherit ancestor's text
alignment setting.

Make it so that alignment is only applied on a P node.
https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-textAlign
This commit is contained in:
Denise LaFayette 2021-04-27 11:29:37 -07:00
parent 1d96d6b6b0
commit 5ef0ba4171
3 changed files with 28 additions and 10 deletions
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24
library/core/src/main/java/com/google/android/exoplayer2/text/ttml/TtmlNode.java
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@ -409,17 +409,21 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
if (resolvedStyle != null) {
TtmlRenderUtil.applyStylesToSpan(
text, start, end, resolvedStyle, parent, globalStyles, verticalType);
if (resolvedStyle.getShearPercentage() != TtmlStyle.UNSPECIFIED_SHEAR && TAG_P.equals(tag)) {
// Shear style should only be applied to P nodes
// https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-shear
// The spec doesn't specify the coordinate system to use for block shear
// however the spec shows examples of how different values are expected to be rendered.
// See: https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-shear
// https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-fontShear
// This maps the shear percentage to shear angle in graphics coordinates
regionOutput.setShearDegrees((resolvedStyle.getShearPercentage() * -90) / 100);
if (TAG_P.equals(tag)) {
if (resolvedStyle.getShearPercentage() != TtmlStyle.UNSPECIFIED_SHEAR) {
// Shear style should only be applied to P nodes
// https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-shear
// The spec doesn't specify the coordinate system to use for block shear
// however the spec shows examples of how different values are expected to be rendered.
// See: https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-shear
// https://www.w3.org/TR/2018/REC-ttml2-20181108/#style-attribute-fontShear
// This maps the shear percentage to shear angle in graphics coordinates
regionOutput.setShearDegrees((resolvedStyle.getShearPercentage() * -90) / 100);
}
if (resolvedStyle.getTextAlign() != null) {
regionOutput.setTextAlignment(resolvedStyle.getTextAlign());
}
}
regionOutput.setTextAlignment(resolvedStyle.getTextAlign());
}
}

8
library/core/src/test/java/com/google/android/exoplayer2/text/ttml/TtmlDecoderTest.java
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@ -607,6 +607,14 @@ public final class TtmlDecoderTest {
Cue seventhCue = getOnlyCueAtTimeUs(subtitle, 70_000_000);
assertThat(seventhCue.text.toString()).isEqualTo("No textAlign property");
assertThat(seventhCue.textAlignment).isNull();
Cue eighthCue = getOnlyCueAtTimeUs(subtitle, 80_000_000);
assertThat(eighthCue.text.toString()).isEqualTo("Ancestor start alignment");
assertThat(eighthCue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_NORMAL);
Cue ninthCue = getOnlyCueAtTimeUs(subtitle, 90_000_000);
assertThat(ninthCue.text.toString()).isEqualTo("Not a P node");
assertThat(ninthCue.textAlignment).isNull();
}
@Test

6
testdata/src/test/assets/media/ttml/text_align.xml vendored
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@ -24,5 +24,11 @@
<div>
<p begin="70s" end="78s">No textAlign property</p>
</div>
<div>
<p begin="80s" end="88s" tts:textAlign="start"><span tts:fontSize="50%">Ancestor start</span> alignment</p>
</div>
<div>
<p begin="90s" end="98s"><span tts:textAlign="start">Not a P node</span></p>
</div>
</body>
</tt>