Introduce QFontDatabase::isPrivateFamily()

Some platforms have the concept of private fonts (e.g., OS X and
iOS) which are generally used as system UI fonts. Since 909d3f5c7,
the platform font database has a similar but private API.

[ChangeLog][QtGui][Fonts] Added QFontDatabase::isPrivateFamily()

Change-Id: Ibdce9de534fadbbc3965be8a942c8012edeed209
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>

src/gui/text/qfontdatabase.cpp

@@ -1935,6 +1935,24 @@ bool QFontDatabase::hasFamily(const QString &family) const
 }
 
 
+/*!
+    \since 5.5
+
+    Returns \c true if and only if the \a family font family is private.
+
+    This happens, for instance, on OS X and iOS, where the system UI fonts are not
+    accessible to the user. For completeness, QFontDatabase::families() returns all
+    font families, including the private ones. You should use this function if you
+    are developing a font selection control in order to keep private fonts hidden.
+
+    \sa families()
+*/
+bool QFontDatabase::isPrivateFamily(const QString &family) const
+{
+    return QGuiApplicationPrivate::platformIntegration()->fontDatabase()->isPrivateFontFamily(family);
+}
+
+
 /*!
     Returns the names the \a writingSystem (e.g. for displaying to the
     user in a dialog).

src/gui/text/qfontdatabase.h

@@ -132,6 +132,7 @@ public:
     int weight(const QString &family, const QString &style) const;
 
     bool hasFamily(const QString &family) const;
+    bool isPrivateFamily(const QString &family) const;
 
     static QString writingSystemName(WritingSystem writingSystem);
     static QString writingSystemSample(WritingSystem writingSystem);

src/widgets/dialogs/qfontdialog.cpp

@@ -57,10 +57,6 @@
 #include <private/qdialog_p.h>
 #include <private/qfont_p.h>
 
-#include <QtGui/private/qguiapplication_p.h>
-#include <qpa/qplatformintegration.h>
-#include <qpa/qplatformfontdatabase.h>
-
 QT_BEGIN_NAMESPACE
 
 class QFontListView : public QListView
@@ -482,11 +478,11 @@ void QFontDialogPrivate::updateFamilies()
     const QFontDialog::FontDialogOptions spacingMask = (QFontDialog::ProportionalFonts | QFontDialog::MonospacedFonts);
     const QFontDialog::FontDialogOptions options = q->options();
 
-    QPlatformFontDatabase *pfdb = QGuiApplicationPrivate::platformIntegration()->fontDatabase();
+    QFontDatabase fdb;
 
     QStringList familyNames;
     foreach (const QString &family, fdb.families(writingSystem)) {
-        if (pfdb->isPrivateFontFamily(family))
+        if (fdb.isPrivateFamily(family))
             continue;
 
         if ((options & scalableMask) && (options & scalableMask) != scalableMask) {

src/widgets/widgets/qfontcombobox.cpp

@@ -45,10 +45,6 @@
 #include <QDesktopWidget>
 #include <qdebug.h>
 
-#include <QtGui/private/qguiapplication_p.h>
-#include <qpa/qplatformintegration.h>
-#include <qpa/qplatformfontdatabase.h>
-
 QT_BEGIN_NAMESPACE
 
 static QFontDatabase::WritingSystem writingSystemFromScript(QLocale::Script script)
@@ -324,10 +320,8 @@ void QFontComboBoxPrivate::_q_updateModel()
     int offset = 0;
     QFontInfo fi(currentFont);
 
-    QPlatformFontDatabase *pfdb = QGuiApplicationPrivate::platformIntegration()->fontDatabase();
-
     for (int i = 0; i < list.size(); ++i) {
-        if (pfdb->isPrivateFontFamily(list.at(i)))
+        if (fdb.isPrivateFamily(list.at(i)))
             continue;
 
         if ((filters & scalableMask) && (filters & scalableMask) != scalableMask) {