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Fix divide by zero when opening font on invalid image

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If you open a QFont on an invalid image, its dpi will be 0. In
other places we check for this before calculating the point
size, but this was missing in one spot, causing divide by
zero.

This would happen e.g. in the tst_QFontMetrics::same() test.
While it would pass normally, running this with an undefined sanitizer build would warn about the division by zero.

There's nothing useful we can do with the fonts on the invalid
image, so like in the other places, we just leave the point size
as is when this happens.

Pick-to: 5.15 6.5 6.8 6.9
Change-Id: I4769e23e2b4dbb92f675cb8a77f8554c90bc2afd
Reviewed-by: Robert Löhning <robert.loehning@qt.io>
This commit is contained in:
Eskil Abrahamsen Blomfeldt 2025-02-07 10:29:18 +01:00
parent 83a4128ecb
commit c136de2deb
1 changed files with 2 additions and 1 deletions
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3
src/gui/text/qfontdatabase.cpp
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@ -2828,7 +2828,8 @@ void QFontDatabasePrivate::load(const QFontPrivate *d, int script)
req.pixelSize = std::floor(((req.pointSize * d->dpi) / 72) * 100 + 0.5) / 100;
req.pixelSize = qRound(req.pixelSize);
}
if (req.pointSize < 0)
if (req.pointSize < 0 && d->dpi > 0)
req.pointSize = req.pixelSize*72.0/d->dpi;
// respect the fallback families that might be passed through the request