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, 13 insertions, 0 deletions

diff --git a/src/gui/text/qfontengine_ft.cpp b/src/gui/text/qfontengine_ft.cpp
index 51b1418bc3..b79fa6e9db 100644
--- a/src/gui/text/qfontengine_ft.cpp
+++ b/src/gui/text/qfontengine_ft.cpp
@@ -414,6 +414,7 @@ QFontEngine::Properties QFreetypeFace::properties() const
     p.italicAngle = 0;
     p.capHeight = p.ascent;
     p.lineWidth = face->underline_thickness;
+
     return p;
 }
 
@@ -1299,6 +1300,18 @@ QFixed QFontEngineFT::ascent() const
     return v;
 }
 
+QFixed QFontEngineFT::capHeight() const
+{
+    TT_OS2 *os2 = (TT_OS2 *)FT_Get_Sfnt_Table(freetype->face, ft_sfnt_os2);
+    if (os2 && os2->version >= 2) {
+        lockFace();
+        QFixed answer = QFixed::fromFixed(FT_MulFix(os2->sCapHeight, freetype->face->size->metrics.y_scale));
+        unlockFace();
+        return answer;
+    }
+    return calculatedCapHeight();
+}
+
 QFixed QFontEngineFT::descent() const
 {
     QFixed v = QFixed::fromFixed(-metrics.descender);