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Use typographic font metrics when the font requests.

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FreeType always returns the 'hhea' font metrics for ascent and descent,
and ignores the 'OS/2'::fsSelection::UseTypoMetrics bit. (It also
ignores the VDMX table, which makes this change correct.) This change
uses the typographic font metrics when the font requests their use.

Review URL: https://codereview.chromium.org/1020643002
This commit is contained in:
bungeman 2015-03-19 10:43:57 -07:00 committed by Commit bot
parent f87cbcdf9f
commit 665b038b57
1 changed files with 14 additions and 3 deletions
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17
src/ports/SkFontHost_FreeType.cpp
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@ -1315,9 +1315,20 @@ void SkScalerContext_FreeType::generateFontMetrics(SkPaint::FontMetrics* metrics
SkScalar ascent, descent, leading, xmin, xmax, ymin, ymax;
SkScalar underlineThickness, underlinePosition;
if (face->face_flags & FT_FACE_FLAG_SCALABLE) { // scalable outline font
ascent = -SkIntToScalar(face->ascender) / upem;
descent = -SkIntToScalar(face->descender) / upem;
leading = SkIntToScalar(face->height + (face->descender - face->ascender)) / upem;
// FreeType will always use HHEA metrics if they're not zero.
// It completely ignores the OS/2 fsSelection::UseTypoMetrics bit.
// It also ignores the VDMX tables, which are also of interest here
// (and override everything else when they apply).
static const int kUseTypoMetricsMask = (1 << 7);
if (os2 && os2->version != 0xFFFF && (os2->fsSelection & kUseTypoMetricsMask)) {
ascent = -SkIntToScalar(os2->sTypoAscender) / upem;
descent = -SkIntToScalar(os2->sTypoDescender) / upem;
leading = SkIntToScalar(os2->sTypoLineGap) / upem;
} else {
ascent = -SkIntToScalar(face->ascender) / upem;
descent = -SkIntToScalar(face->descender) / upem;
leading = SkIntToScalar(face->height + (face->descender - face->ascender)) / upem;
}
xmin = SkIntToScalar(face->bbox.xMin) / upem;
xmax = SkIntToScalar(face->bbox.xMax) / upem;
ymin = -SkIntToScalar(face->bbox.yMin) / upem;