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>

3 files changed, 29 insertions, 2 deletions

diff --git a/tests/auto/gui/text/qrawfont/testdata.qrc b/tests/auto/gui/text/qrawfont/testdata.qrc
index 8f8e32ed24..c7ac9641d1 100644
--- a/tests/auto/gui/text/qrawfont/testdata.qrc
+++ b/tests/auto/gui/text/qrawfont/testdata.qrc
@@ -1,6 +1,7 @@
 <RCC>
     <qresource prefix="/">
         <file>testfont_bold_italic.ttf</file>
+        <file>testfont_os2_v1.ttf</file>
         <file alias="testfont.ttf">../../../shared/resources/testfont.ttf</file>
     </qresource>
 </RCC>
diff --git a/tests/auto/gui/text/qrawfont/testfont_os2_v1.ttf b/tests/auto/gui/text/qrawfont/testfont_os2_v1.ttf
new file mode 100644
index 0000000000..ee8b67d892
--- /dev/null
+++ b/tests/auto/gui/text/qrawfont/testfont_os2_v1.ttf
diff --git a/tests/auto/gui/text/qrawfont/tst_qrawfont.cpp b/tests/auto/gui/text/qrawfont/tst_qrawfont.cpp
index 471b32dd50..3cf108ed62 100644
--- a/tests/auto/gui/text/qrawfont/tst_qrawfont.cpp
+++ b/tests/auto/gui/text/qrawfont/tst_qrawfont.cpp
@@ -93,6 +93,7 @@ private slots:
 private:
     QString testFont;
     QString testFontBoldItalic;
+    QString testFontOs2V1;
 #endif // QT_NO_RAWFONT
 };
 
@@ -110,6 +111,7 @@ void tst_QRawFont::initTestCase()
 {
     testFont = QFINDTESTDATA("testfont.ttf");
     testFontBoldItalic = QFINDTESTDATA("testfont_bold_italic.ttf");
+    testFontOs2V1 = QFINDTESTDATA("testfont_os2_v1.ttf");
     if (testFont.isEmpty() || testFontBoldItalic.isEmpty())
         QFAIL("qrawfont unittest font files not found!");
 
@@ -184,6 +186,7 @@ void tst_QRawFont::correctFontData_data()
     QTest::addColumn<QFont::HintingPreference>("hintingPreference");
     QTest::addColumn<qreal>("unitsPerEm");
     QTest::addColumn<qreal>("pixelSize");
+    QTest::addColumn<int>("capHeight");
 
     int hintingPreferences[] = {
         int(QFont::PreferDefaultHinting),
@@ -207,7 +210,8 @@ void tst_QRawFont::correctFontData_data()
                 << QFont::Normal
                 << QFont::HintingPreference(*hintingPreference)
                 << qreal(1000.0)
-                << qreal(10.0);
+                << qreal(10.0)
+                << 7;
 
         fileName = testFontBoldItalic;
         title = fileName
@@ -221,7 +225,23 @@ void tst_QRawFont::correctFontData_data()
                 << QFont::Bold
                 << QFont::HintingPreference(*hintingPreference)
                 << qreal(1000.0)
-                << qreal(10.0);
+                << qreal(10.0)
+                << 7;
+
+        fileName = testFontOs2V1;
+        title = fileName
+              + QLatin1String(": hintingPreference=")
+              + QString::number(*hintingPreference);
+
+        QTest::newRow(qPrintable(title))
+                << fileName
+                << QString::fromLatin1("QtBidiTestFont")
+                << QFont::StyleNormal
+                << QFont::Normal
+                << QFont::HintingPreference(*hintingPreference)
+                << qreal(1000.0)
+                << qreal(10.0)
+                << 7;
 
         ++hintingPreference;
     }
@@ -236,6 +256,7 @@ void tst_QRawFont::correctFontData()
     QFETCH(QFont::HintingPreference, hintingPreference);
     QFETCH(qreal, unitsPerEm);
     QFETCH(qreal, pixelSize);
+    QFETCH(int, capHeight);
 
     QRawFont font(fileName, 10, hintingPreference);
     QVERIFY(font.isValid());
@@ -246,6 +267,11 @@ void tst_QRawFont::correctFontData()
     QCOMPARE(font.hintingPreference(), hintingPreference);
     QCOMPARE(font.unitsPerEm(), unitsPerEm);
     QCOMPARE(font.pixelSize(), pixelSize);
+
+    // Some platforms return the actual fractional height of the
+    // H character when the value is missing from the OS/2 table,
+    // so we ceil it off to match (any touched pixel counts).
+    QCOMPARE(qCeil(font.capHeight()), capHeight);
 }
 
 void tst_QRawFont::glyphIndices()