Implement QFontMetrics::inFont(uint) which takes UCS-4 encoded char

Support unicode characters which are not representable in 16 bits in
QFontMetrics::inFont() to enable font selection algorithms for unicode
ranges that require surrogates.

Task-number: QTBUG-12638
Reviewed-by: Simon Hausmann

6 files changed, 61 insertions, 2 deletions

diff --git a/src/gui/text/qfontmetrics.cpp b/src/gui/text/qfontmetrics.cpp
index d02e841..f2591ce 100644
--- a/src/gui/text/qfontmetrics.cpp
+++ b/src/gui/text/qfontmetrics.cpp
@@ -443,6 +443,21 @@ bool QFontMetrics::inFont(QChar ch) const
 }
 
 /*!
+   Returns true if the character encoded in UCS-4/UTF-32 is a valid
+   character in the font; otherwise returns false.
+*/
+bool QFontMetrics::inFontUcs4(uint ucs4) const
+{
+    const int script = QUnicodeTables::script(ucs4);
+    QFontEngine *engine = d->engineForScript(script);
+    Q_ASSERT(engine != 0);
+    if (engine->type() == QFontEngine::Box)
+        return false;
+    QString utf16 = QString::fromUcs4(&ucs4, 1);
+    return engine->canRender(utf16.data(), utf16.length());
+}
+
+/*!
     Returns the left bearing of character \a ch in the font.
 
     The left bearing is the right-ward distance of the left-most pixel
@@ -1315,6 +1330,21 @@ bool QFontMetricsF::inFont(QChar ch) const
 }
 
 /*!
+   Returns true if the character encoded in UCS-4/UTF-32 is a valid
+   character in the font; otherwise returns false.
+*/
+bool QFontMetricsF::inFontUcs4(uint ucs4) const
+{
+    const int script = QUnicodeTables::script(ucs4);
+    QFontEngine *engine = d->engineForScript(script);
+    Q_ASSERT(engine != 0);
+    if (engine->type() == QFontEngine::Box)
+        return false;
+    QString utf16 = QString::fromUcs4(&ucs4, 1);
+    return engine->canRender(utf16.data(), utf16.length());
+}
+
+/*!
     Returns the left bearing of character \a ch in the font.
 
     The left bearing is the right-ward distance of the left-most pixel
@@ -1779,7 +1809,7 @@ qreal QFontMetricsF::lineWidth() const
 
     Use the boundingRect() function in combination with
     QString::left() instead.
-     
+
     \oldcode
         QRect rect = boundingRect(text, len);
     \newcode
diff --git a/src/gui/text/qfontmetrics.h b/src/gui/text/qfontmetrics.h
index 2518b54..9911ad2 100644
--- a/src/gui/text/qfontmetrics.h
+++ b/src/gui/text/qfontmetrics.h
@@ -85,6 +85,7 @@ public:
     int averageCharWidth() const;
 
     bool inFont(QChar) const;
+    bool inFontUcs4(uint ucs4) const;
 
     int leftBearing(QChar) const;
     int rightBearing(QChar) const;
@@ -162,6 +163,7 @@ public:
     qreal averageCharWidth() const;
 
     bool inFont(QChar) const;
+    bool inFontUcs4(uint ucs4) const;
 
     qreal leftBearing(QChar) const;
     qreal rightBearing(QChar) const;
diff --git a/tests/auto/qfontmetrics/qfontmetrics.pro b/tests/auto/qfontmetrics/qfontmetrics.pro
index 51a7057..c0dc1ab 100644
--- a/tests/auto/qfontmetrics/qfontmetrics.pro
+++ b/tests/auto/qfontmetrics/qfontmetrics.pro
@@ -1,4 +1,4 @@
 load(qttest_p4)
 SOURCES  += tst_qfontmetrics.cpp
-
+RESOURCES += testfont.qrc
 
diff --git a/tests/auto/qfontmetrics/testfont.qrc b/tests/auto/qfontmetrics/testfont.qrc
new file mode 100644
index 0000000..bc0c0b0
--- /dev/null
+++ b/tests/auto/qfontmetrics/testfont.qrc
@@ -0,0 +1,5 @@
+<RCC>
+    <qresource prefix="/fonts">
+        <file>ucs4font.ttf</file>
+    </qresource>
+</RCC>
diff --git a/tests/auto/qfontmetrics/tst_qfontmetrics.cpp b/tests/auto/qfontmetrics/tst_qfontmetrics.cpp
index a22d624..4250415 100644
--- a/tests/auto/qfontmetrics/tst_qfontmetrics.cpp
+++ b/tests/auto/qfontmetrics/tst_qfontmetrics.cpp
@@ -74,6 +74,7 @@ private slots:
     void bypassShaping();
     void elidedMultiLength();
     void elidedMultiLengthF();
+    void inFontUcs4();
 };
 
 tst_QFontMetrics::tst_QFontMetrics()
@@ -266,5 +267,26 @@ void tst_QFontMetrics::elidedMultiLengthF()
     elidedMultiLength_helper<QFontMetricsF>();
 }
 
+void tst_QFontMetrics::inFontUcs4()
+{
+    int id = QFontDatabase::addApplicationFont(":/fonts/ucs4font.ttf");
+    QVERIFY(id >= 0);
+
+    QFont font("QtTestUcs4");
+    {
+        QFontMetrics fm(font);
+
+        QVERIFY(fm.inFontUcs4(0x1D7FF));
+    }
+
+    {
+        QFontMetricsF fm(font);
+
+        QVERIFY(fm.inFontUcs4(0x1D7FF));
+    }
+
+    QFontDatabase::removeApplicationFont(id);
+}
+
 QTEST_MAIN(tst_QFontMetrics)
 #include "tst_qfontmetrics.moc"
diff --git a/tests/auto/qfontmetrics/ucs4font.ttf b/tests/auto/qfontmetrics/ucs4font.ttf
new file mode 100644
index 0000000..31b6997
--- /dev/null
+++ b/tests/auto/qfontmetrics/ucs4font.ttf