Fix issue with mispositioned family name i QFontComboBox

Mac OS X 10.7 comes with the family of Stix fonts, some
of which exposed an ugly layout bug in the QFontComboBox
because the ascent/descent ratio is very large due to
a very high ascent, so centering the text vertically might
cause most of the text to be clipped away.

The solution is to detect when the ascent is larger than the
height of the destination rectangle (hence a large part of the
characters will be clipped) and use the actual bounding rect
for centralizing instead. Since this only happens for a
very few of the fonts, the overhead of getting the bounding
rect should be tolerable.

Task-number: QTBUG-26691
Change-Id: I4f1a9b3c63138fde4dfdfa99d8581458c59b7ff6
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/gui/widgets/qfontcombobox.cpp b/src/gui/widgets/qfontcombobox.cpp
index b0a0828..18510bc 100644
--- a/src/gui/widgets/qfontcombobox.cpp
+++ b/src/gui/widgets/qfontcombobox.cpp
@@ -164,7 +164,18 @@ void QFontFamilyDelegate::paint(QPainter *painter,
 
     QFont old = painter->font();
     painter->setFont(font);
-    painter->drawText(r, Qt::AlignVCenter|Qt::AlignLeading|Qt::TextSingleLine, text);
+
+    // If the ascent of the font is larger than the height of the rect,
+    // we will clip the text, so it's better to align the tight bounding rect in this case
+    // This is specifically for fonts where the ascent is very large compared to
+    // the descent, like certain of the Stix family.
+    QFontMetricsF fontMetrics(font);
+    if (fontMetrics.ascent() > r.height()) {
+        QRectF tbr = fontMetrics.tightBoundingRect(text);
+        painter->drawText(r.x(), r.y() + (r.height() + tbr.height()) / 2.0, text);
+    } else {
+        painter->drawText(r, Qt::AlignVCenter|Qt::AlignLeading|Qt::TextSingleLine, text);
+    }
 
     if (writingSystem != QFontDatabase::Any)
         system = writingSystem;