macOS: Defer population of localized font family aliases until needed

Getting the localized family name of a font involves quite a bit of work
internally in CoreText, e.g. creating and sorting font descriptors.

By deferring population of family aliases until a font match misses
we shave off ~1 second of startup time for applications that use non-
localized font families (most applications).

Change-Id: I021952c311c0d70d7769ccf764dbf997ebf30a4b
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

src/gui/text/qfontdatabase.cpp

@@ -2678,6 +2678,10 @@ QFontEngine *QFontDatabase::findFont(const QFontDef &request, int script)
     QtFontDesc desc;
     QList<int> blackListed;
     int index = match(multi ? QChar::Script_Common : script, request, family_name, foundry_name, &desc, blackListed);
+    if (index < 0 && QGuiApplicationPrivate::platformIntegration()->fontDatabase()->populateFamilyAliases()) {
+        // We populated familiy aliases (e.g. localized families), so try again
+        index = match(multi ? QChar::Script_Common : script, request, family_name, foundry_name, &desc, blackListed);
+    }
     if (index >= 0) {
         engine = loadEngine(script, request, desc.family, desc.foundry, desc.style, desc.size);
         if (engine)

src/gui/text/qplatformfontdatabase.h

@@ -104,6 +104,7 @@ class Q_GUI_EXPORT QPlatformFontDatabase
 public:
     virtual ~QPlatformFontDatabase();
     virtual void populateFontDatabase();
+    virtual bool populateFamilyAliases() { return false; }
     virtual void populateFamily(const QString &familyName);
     virtual void invalidate();
 

src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm

@@ -113,6 +113,7 @@ static NSInteger languageMapSort(id obj1, id obj2, void *context)
 #endif
 
 QCoreTextFontDatabase::QCoreTextFontDatabase()
+    : m_hasPopulatedAliases(false)
 {
 #ifdef Q_OS_MACX
     QSettings appleSettings(QLatin1String("apple.com"));
@@ -200,18 +201,8 @@ static CFArrayRef availableFamilyNames()
 void QCoreTextFontDatabase::populateFontDatabase()
 {
     QCFType<CFArrayRef> familyNames = availableFamilyNames();
-    const int numberOfFamilies = CFArrayGetCount(familyNames);
+    for (NSString *familyName in familyNames.as<const NSArray *>())
-    for (int i = 0; i < numberOfFamilies; ++i) {
+        QPlatformFontDatabase::registerFontFamily(QString::fromNSString(familyName));
-        CFStringRef familyNameRef = (CFStringRef) CFArrayGetValueAtIndex(familyNames, i);
-        QString familyName = QString::fromCFString(familyNameRef);
-        QPlatformFontDatabase::registerFontFamily(familyName);
-
-#if defined(Q_OS_OSX)
-        QString localizedFamilyName = QString::fromNSString([[NSFontManager sharedFontManager] localizedNameForFamily:(NSString*)familyNameRef face:nil]);
-        if (familyName != localizedFamilyName)
-            QPlatformFontDatabase::registerAliasToFontFamily(familyName, localizedFamilyName);
-#endif
-    }
 
     // Force creating the theme fonts to get the descriptors in m_systemFontDescriptors
     if (m_themeFonts.isEmpty())
@@ -219,6 +210,31 @@ void QCoreTextFontDatabase::populateFontDatabase()
 
     Q_FOREACH (CTFontDescriptorRef fontDesc, m_systemFontDescriptors)
         populateFromDescriptor(fontDesc);
+
+    Q_ASSERT(!m_hasPopulatedAliases);
+}
+
+bool QCoreTextFontDatabase::populateFamilyAliases()
+{
+#if defined(Q_OS_MACOS)
+    if (m_hasPopulatedAliases)
+        return false;
+
+    QCFType<CFArrayRef> familyNames = availableFamilyNames();
+    for (NSString *familyName in familyNames.as<const NSArray *>()) {
+        NSFontManager *fontManager = [NSFontManager sharedFontManager];
+        NSString *localizedFamilyName = [fontManager localizedNameForFamily:familyName face:nil];
+        if (![localizedFamilyName isEqual:familyName]) {
+            QPlatformFontDatabase::registerAliasToFontFamily(
+                QString::fromNSString(familyName),
+                QString::fromNSString(localizedFamilyName));
+        }
+    }
+    m_hasPopulatedAliases = true;
+    return true;
+#else
+    return false;
+#endif
 }
 
 void QCoreTextFontDatabase::populateFamily(const QString &familyName)
@@ -239,6 +255,11 @@ void QCoreTextFontDatabase::populateFamily(const QString &familyName)
         populateFromDescriptor(CTFontDescriptorRef(CFArrayGetValueAtIndex(matchingFonts, i)), familyName);
 }
 
+void QCoreTextFontDatabase::invalidate()
+{
+    m_hasPopulatedAliases = false;
+}
+
 struct FontDescription {
     QCFString familyName;
     QCFString styleName;

src/platformsupport/fontdatabases/mac/qcoretextfontdatabase_p.h

@@ -75,7 +75,9 @@ public:
     QCoreTextFontDatabase();
     ~QCoreTextFontDatabase();
     void populateFontDatabase() Q_DECL_OVERRIDE;
+    bool populateFamilyAliases() override;
     void populateFamily(const QString &familyName) Q_DECL_OVERRIDE;
+    void invalidate() override;
 
     QStringList fallbacksForFamily(const QString &family, QFont::Style style, QFont::StyleHint styleHint, QChar::Script script) const Q_DECL_OVERRIDE;
     QStringList addApplicationFont(const QByteArray &fontData, const QString &fileName) Q_DECL_OVERRIDE;
@@ -96,6 +98,7 @@ private:
 
     mutable QSet<CTFontDescriptorRef> m_systemFontDescriptors;
     mutable QHash<QPlatformTheme::Font, QFont *> m_themeFonts;
+    bool m_hasPopulatedAliases;
 };
 
 // Split out into separate template class so that the compiler doesn't have