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Workaround a bug in Core Text to select Light fonts 

Currently in Core Text there is not proper way to select fonts with
Light weight, for example:
QFont font("Helvetica"); font.setWeight(QFont::Light);
will give you Helvetica-Light, as with:
QFont font("Helvetica"); font.setWeight(QFont::Normal);
because of a bug in Core Text, applying 0 symbolic traits with
CTFontCreateCopyWithSymbolicTraits will always return the Light
variant of that font family. Thus, we should only do this unless
symbolicTraits is not 0 or font.weight is not Normal (Light is not
a symbolic trait, but CT doesn't support selecting Light weight
numerically).

Reviewed-by: Eskil
(cherry picked from commit 4d5b8f66d82e9087d9d58a4e76e6b46ce7bb53cc)

Change-Id: I37a970aba5019a13b9f3bc43b7fb594b74a1aa37
Reviewed-on: http://codereview.qt.nokia.com/124
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
bb10
Jiang Jiang 2011-05-16 10:20:54 +02:00 committed by Qt Continuous Integration System
parent 1909e03882
commit ffc1950591
1 changed files with 6 additions and 1 deletions
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7
src/gui/text/qfontengine_coretext.mm
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@ -100,7 +100,12 @@ QCoreTextFontEngineMulti::QCoreTextFontEngineMulti(const QCFString &name, const
QCFType<CTFontDescriptorRef> descriptor = CTFontDescriptorCreateWithNameAndSize(name, fontDef.pixelSize);
QCFType<CTFontRef> baseFont = CTFontCreateWithFontDescriptor(descriptor, fontDef.pixelSize, &transform);
ctfont = CTFontCreateCopyWithSymbolicTraits(baseFont, fontDef.pixelSize, &transform, symbolicTraits, symbolicTraits);
ctfont = NULL;
// There is a side effect in Core Text: if we apply 0 as symbolic traits to a font in normal weight,
// we will get the light version of that font (while the way supposed to work doesn't:
// setting kCTFontWeightTrait to some value between -1.0 to 0.0 has no effect on font selection)
if (fontDef.weight != QFont::Normal || symbolicTraits)
ctfont = CTFontCreateCopyWithSymbolicTraits(baseFont, fontDef.pixelSize, &transform, symbolicTraits, symbolicTraits);
// CTFontCreateCopyWithSymbolicTraits returns NULL if we ask for a trait that does
// not exist for the given font. (for example italic)