Added capHeight() to QRawFont and QFontMetrics(F)

Cap height is an important metric of font, in particular it is
required to make decent implementation of "initial-letter"
CSS property in QtWebKit.

Note that some fonts lack cap height metadata, so we need to
fall back to measuring H letter height.

Change-Id: Icf69d92159d070889085e20d31f2e397d796d940
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/gui/text/qrawfont.cpp b/src/gui/text/qrawfont.cpp
index 19ac4f1dbc..1fbe0ce9d1 100644
--- a/src/gui/text/qrawfont.cpp
+++ b/src/gui/text/qrawfont.cpp
@@ -325,6 +325,23 @@ qreal QRawFont::ascent() const
 }
 
 /*!
+   Returns the cap height of this QRawFont in pixel units.
+
+   \since 5.8
+
+   The cap height of a font is the height of a capital letter above
+   the baseline. It specifically is the height of capital letters
+   that are flat - such as H or I - as opposed to round letters such
+   as O, or pointed letters like A, both of which may display overshoot.
+
+   \sa QFontMetricsF::capHeight()
+*/
+qreal QRawFont::capHeight() const
+{
+    return d->isValid() ? d->fontEngine->capHeight().toReal() : 0.0;
+}
+
+/*!
    Returns the descent of this QRawFont in pixel units.
 
    \sa QFontMetricsF::descent()