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

2 files changed, 33 insertions, 1 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;