Details
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Bug
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Resolution: Unresolved
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P3: Somewhat important
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None
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5.9.2, 5.10.1
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None
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macOS Sierra 10.12.6(MacBook Pro Retina, 15-inch, Mid 2014)
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macOS
Description
Drawing text with underline using QPainter::drawGlyphRun on the retina display is incorrect if pixelSize < 32. Please see attached example.
Please take a look at the code (QT_MAX_CACHED_GLYPH_SIZE == 64):
bool QPaintEngineEx::shouldDrawCachedGlyphs(QFontEngine *fontEngine, const QTransform &m) const { if (fontEngine->glyphFormat == QFontEngine::Format_ARGB) return true; qreal pixelSize = fontEngine->fontDef.pixelSize; return (pixelSize * pixelSize * qAbs(m.determinant())) < QT_MAX_CACHED_GLYPH_SIZE * QT_MAX_CACHED_GLYPH_SIZE; }
And at this code in QPainter::drawGlyphRun:
QRawFontPrivate *fontD = QRawFontPrivate::get(font);
bool engineRequiresPretransformedGlyphPositions = d->extended
? d->extended->requiresPretransformedGlyphPositions(fontD->fontEngine, d->state->matrix)
: d->engine->type() != QPaintEngine::CoreGraphics && !d->state->matrix.isAffine();
for (int i=0; i<count; ++i) {
QPointF processedPosition = position + glyphPositions[i];
if (engineRequiresPretransformedGlyphPositions)
processedPosition = d->state->transform().map(processedPosition);
fixedPointPositions[i] = QFixedPoint::fromPointF(processedPosition);
}
The engineRequiresPretransformedGlyphPositions is true because of the first code block.
The underline size and position are calculated after the second code block.
