CoreText: Modernize style hint fallback lookup

The DefaultFontFallbacks.plist system file that we used for looking up
style fallbacks does not exists in macOS 10.15, nor did it ever exists
on iOS. Instead of relying on this file, we hard-code a set of default
families, that we then look up the fallbacks for.

The result of QFont::defaultFamily() on macOS is now:

  QFont::Helvetica --> "Helvetica"
  QFont::Times --> "Times New Roman"
  QFont::Courier --> "American Typewriter"
  QFont::OldEnglish --> ""
  QFont::System --> "Lucida Grande"
  QFont::AnyStyle --> "Lucida Grande"
  QFont::Cursive --> "Apple Chancery"
  QFont::Monospace --> "Menlo"
  QFont::Fantasy --> "Zapfino"

And on iOS:

  QFont::Helvetica --> "Helvetica"
  QFont::Times --> "Times New Roman"
  QFont::Courier --> "American Typewriter"
  QFont::OldEnglish --> ""
  QFont::System --> "Helvetica"
  QFont::AnyStyle --> "Helvetica"
  QFont::Cursive --> ""
  QFont::Monospace --> "Menlo"
  QFont::Fantasy --> "Zapfino"

Fixes: QTBUG-78240
Change-Id: Ie9bc13c9c1031d89f024199e4736a046c568a48d
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

2 files changed, 73 insertions, 129 deletions

diff --git a/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm b/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
index 047773d8e3..a52e157768 100644
--- a/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
+++ b/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase.mm
@@ -100,20 +100,6 @@ static const char *languageForWritingSystem[] = {
 };
 enum { LanguageCount = sizeof(languageForWritingSystem) / sizeof(const char *) };
 
-#ifdef Q_OS_OSX
-static NSInteger languageMapSort(id obj1, id obj2, void *context)
-{
-    NSArray<NSString *> *map1 = reinterpret_cast<NSArray<NSString *> *>(obj1);
-    NSArray<NSString *> *map2 = reinterpret_cast<NSArray<NSString *> *>(obj2);
-    NSArray<NSString *> *languages = reinterpret_cast<NSArray<NSString *> *>(context);
-
-    NSString *lang1 = [map1 objectAtIndex:0];
-    NSString *lang2 = [map2 objectAtIndex:0];
-
-    return [languages indexOfObject:lang1] - [languages indexOfObject:lang2];
-}
-#endif
-
 QCoreTextFontDatabase::QCoreTextFontDatabase()
     : m_hasPopulatedAliases(false)
 {
@@ -406,142 +392,99 @@ template class QCoreTextFontDatabaseEngineFactory<QCoreTextFontEngine>;
 template class QCoreTextFontDatabaseEngineFactory<QFontEngineFT>;
 #endif
 
-QFont::StyleHint styleHintFromNSString(NSString *style)
+QStringList QCoreTextFontDatabase::fallbacksForFamily(const QString &family)
 {
-    if ([style isEqual: @"sans-serif"])
-        return QFont::SansSerif;
-    else if ([style isEqual: @"monospace"])
-        return QFont::Monospace;
-    else if ([style isEqual: @"cursive"])
-        return QFont::Cursive;
-    else if ([style isEqual: @"serif"])
-        return QFont::Serif;
-    else if ([style isEqual: @"fantasy"])
-        return QFont::Fantasy;
-    else // if ([style isEqual: @"default"])
-        return QFont::AnyStyle;
-}
+    if (family.isEmpty())
+        return QStringList();
 
-#ifdef Q_OS_OSX
-static QString familyNameFromPostScriptName(NSString *psName)
-{
-    QCFType<CTFontDescriptorRef> fontDescriptor = (CTFontDescriptorRef) CTFontDescriptorCreateWithNameAndSize((CFStringRef)psName, 12.0);
-    QCFString familyName = (CFStringRef) CTFontDescriptorCopyAttribute(fontDescriptor, kCTFontFamilyNameAttribute);
-    QString name = QString::fromCFString(familyName);
-    if (name.isEmpty())
-        qWarning() << "QCoreTextFontDatabase: Failed to resolve family name for PostScript name " << QString::fromCFString((CFStringRef)psName);
+    auto attributes = @{ id(kCTFontFamilyNameAttribute): family.toNSString() };
+    QCFType<CTFontDescriptorRef> fontDescriptor = CTFontDescriptorCreateWithAttributes(CFDictionaryRef(attributes));
+    if (!fontDescriptor) {
+        qWarning() << "Failed to create fallback font descriptor for" << family;
+        return QStringList();
+    }
 
-    return name;
-}
-#endif
+    QCFType<CTFontRef> font = CTFontCreateWithFontDescriptor(fontDescriptor, 12.0, 0);
+    if (!font) {
+        qWarning() << "Failed to create fallback font for" << family;
+        return QStringList();
+    }
 
-static void addExtraFallbacks(QStringList *fallbackList)
-{
-#if defined(Q_OS_MACOS)
-    // Since we are only returning a list of default fonts for the current language, we do not
-    // cover all unicode completely. This was especially an issue for some of the common script
-    // symbols such as mathematical symbols, currency or geometric shapes. To minimize the risk
-    // of missing glyphs, we add Arial Unicode MS as a final fail safe, since this covers most
-    // of Unicode 2.1.
-    if (!fallbackList->contains(QStringLiteral("Arial Unicode MS")))
-        fallbackList->append(QStringLiteral("Arial Unicode MS"));
-    // Since some symbols (specifically Braille) are not in Arial Unicode MS, we
-    // add Apple Symbols to cover those too.
-    if (!fallbackList->contains(QStringLiteral("Apple Symbols")))
-        fallbackList->append(QStringLiteral("Apple Symbols"));
-#else
-    Q_UNUSED(fallbackList)
-#endif
+    QCFType<CFArrayRef> cascadeList = CFArrayRef(CTFontCopyDefaultCascadeListForLanguages(font,
+        (CFArrayRef)[NSUserDefaults.standardUserDefaults stringArrayForKey:@"AppleLanguages"]));
+    if (!cascadeList) {
+        qWarning() << "Failed to create fallback cascade list for" << family;
+        return QStringList();
+    }
+
+    QStringList fallbackList;
+    const int numCascades = CFArrayGetCount(cascadeList);
+    for (int i = 0; i < numCascades; ++i) {
+        CTFontDescriptorRef fontFallback = CTFontDescriptorRef(CFArrayGetValueAtIndex(cascadeList, i));
+        QCFString fallbackFamilyName = CFStringRef(CTFontDescriptorCopyAttribute(fontFallback, kCTFontFamilyNameAttribute));
+        fallbackList.append(QString::fromCFString(fallbackFamilyName));
+    }
+
+    return fallbackList;
 }
 
 QStringList QCoreTextFontDatabase::fallbacksForFamily(const QString &family, QFont::Style style, QFont::StyleHint styleHint, QChar::Script script) const
 {
     Q_UNUSED(style);
-    Q_UNUSED(script);
 
     QMacAutoReleasePool pool;
 
-    static QHash<QString, QStringList> fallbackLists;
-
-    if (!family.isEmpty()) {
-        QCFType<CFMutableDictionaryRef> attributes = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
-        CFDictionaryAddValue(attributes, kCTFontFamilyNameAttribute, QCFString(family));
-        if (QCFType<CTFontDescriptorRef> fontDescriptor = CTFontDescriptorCreateWithAttributes(attributes)) {
-            if (QCFType<CTFontRef> font = CTFontCreateWithFontDescriptor(fontDescriptor, 12.0, 0)) {
-                NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
-                NSArray *languages = [defaults stringArrayForKey: @"AppleLanguages"];
-
-                QCFType<CFArrayRef> cascadeList = (CFArrayRef) CTFontCopyDefaultCascadeListForLanguages(font, (CFArrayRef) languages);
-                if (cascadeList) {
-                    QStringList fallbackList;
-                    const int numCascades = CFArrayGetCount(cascadeList);
-                    for (int i = 0; i < numCascades; ++i) {
-                        CTFontDescriptorRef fontFallback = (CTFontDescriptorRef) CFArrayGetValueAtIndex(cascadeList, i);
-                        QCFString fallbackFamilyName = (CFStringRef) CTFontDescriptorCopyAttribute(fontFallback, kCTFontFamilyNameAttribute);
-                        fallbackList.append(QString::fromCFString(fallbackFamilyName));
-                    }
-
-                    addExtraFallbacks(&fallbackList);
-                    extern QStringList qt_sort_families_by_writing_system(QChar::Script, const QStringList &);
-                    fallbackList = qt_sort_families_by_writing_system(script, fallbackList);
-
-                    return fallbackList;
+    QStringList fallbackList = fallbacksForFamily(family);
+
+    if (fallbackList.isEmpty()) {
+        // We were not able to find a fallback for the specific family,
+        // or the family was empty, so we fall back to the style hint.
+        QString styleFamily = [styleHint]{
+            switch (styleHint) {
+                case QFont::SansSerif: return QStringLiteral("Helvetica");
+                case QFont::Serif: return QStringLiteral("Times New Roman");
+                case QFont::Monospace: return QStringLiteral("Menlo");
+#ifdef Q_OS_MACOS
+                case QFont::Cursive: return QStringLiteral("Apple Chancery");
+#endif
+                case QFont::Fantasy: return QStringLiteral("Zapfino");
+                case QFont::TypeWriter: return QStringLiteral("American Typewriter");
+                case QFont::AnyStyle: Q_FALLTHROUGH();
+                case QFont::System: {
+                    QCFType<CTFontRef> font = CTFontCreateUIFontForLanguage(kCTFontUIFontSystem, 12.0, NULL);
+                    return static_cast<QString>(QCFString(CTFontCopyFullName(font)));
                 }
+                default: return QString(); // No matching font on this platform
             }
+        }();
+        if (!styleFamily.isEmpty()) {
+            fallbackList = fallbacksForFamily(styleFamily);
+            if (!fallbackList.contains(styleFamily))
+                fallbackList.prepend(styleFamily);
         }
     }
 
-    // We were not able to find a fallback for the specific family,
-    // so we fall back to the stylehint.
-
-    static const QString styleLookupKey = QString::fromLatin1(".QFontStyleHint_%1");
-
-    static bool didPopulateStyleFallbacks = false;
-    if (!didPopulateStyleFallbacks) {
-#if defined(Q_OS_MACX)
-        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
-        NSArray<NSString *> *languages = [defaults stringArrayForKey:@"AppleLanguages"];
-
-        NSDictionary<NSString *, id> *fallbackDict = [NSDictionary<NSString *, id> dictionaryWithContentsOfFile:@"/System/Library/Frameworks/ApplicationServices.framework/Frameworks/CoreText.framework/Resources/DefaultFontFallbacks.plist"];
-
-        for (NSString *style in [fallbackDict allKeys]) {
-            NSArray *list = [fallbackDict valueForKey:style];
-            QFont::StyleHint fallbackStyleHint = styleHintFromNSString(style);
-            QStringList fallbackList;
-            for (id item in list) {
-                // sort the array based on system language preferences
-                if ([item isKindOfClass:[NSArray class]]) {
-                    NSArray *langs = [reinterpret_cast<NSArray *>(item)
-                        sortedArrayUsingFunction:languageMapSort context:languages];
-                    for (NSArray<NSString *> *map in langs)
-                        fallbackList.append(familyNameFromPostScriptName([map objectAtIndex:1]));
-                }
-                else if ([item isKindOfClass: [NSString class]])
-                    fallbackList.append(familyNameFromPostScriptName(item));
-            }
-
-            fallbackList.append(QLatin1String("Apple Color Emoji"));
+    if (fallbackList.isEmpty())
+        return fallbackList;
 
-            addExtraFallbacks(&fallbackList);
-            fallbackLists[styleLookupKey.arg(fallbackStyleHint)] = fallbackList;
-        }
-#else
-        QStringList staticFallbackList;
-        staticFallbackList << QString::fromLatin1("Helvetica,Apple Color Emoji,Geeza Pro,Arial Hebrew,Thonburi,Kailasa"
-            "Hiragino Kaku Gothic ProN,.Heiti J,Apple SD Gothic Neo,.Heiti K,Heiti SC,Heiti TC"
-            "Bangla Sangam MN,Devanagari Sangam MN,Gujarati Sangam MN,Gurmukhi MN,Kannada Sangam MN"
-            "Malayalam Sangam MN,Oriya Sangam MN,Sinhala Sangam MN,Tamil Sangam MN,Telugu Sangam MN"
-            "Euphemia UCAS,.PhoneFallback").split(QLatin1String(","));
-
-        for (int i = QFont::Helvetica; i <= QFont::Fantasy; ++i)
-            fallbackLists[styleLookupKey.arg(i)] = staticFallbackList;
+#if defined(Q_OS_MACOS)
+    // Since we are only returning a list of default fonts for the current language, we do not
+    // cover all Unicode completely. This was especially an issue for some of the common script
+    // symbols such as mathematical symbols, currency or geometric shapes. To minimize the risk
+    // of missing glyphs, we add Arial Unicode MS as a final fail safe, since this covers most
+    // of Unicode 2.1.
+    if (!fallbackList.contains(QStringLiteral("Arial Unicode MS")))
+        fallbackList.append(QStringLiteral("Arial Unicode MS"));
+    // Since some symbols (specifically Braille) are not in Arial Unicode MS, we
+    // add Apple Symbols to cover those too.
+    if (!fallbackList.contains(QStringLiteral("Apple Symbols")))
+        fallbackList.append(QStringLiteral("Apple Symbols"));
 #endif
 
-        didPopulateStyleFallbacks = true;
-    }
+    extern QStringList qt_sort_families_by_writing_system(QChar::Script, const QStringList &);
+    fallbackList = qt_sort_families_by_writing_system(script, fallbackList);
 
-    Q_ASSERT(!fallbackLists.isEmpty());
-    return fallbackLists[styleLookupKey.arg(styleHint)];
+    return fallbackList;
 }
 
 QStringList QCoreTextFontDatabase::addApplicationFont(const QByteArray &fontData, const QString &fileName)
diff --git a/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase_p.h b/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase_p.h
index 05f6ed641c..45e74b99be 100644
--- a/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase_p.h
+++ b/src/platformsupport/fontdatabases/mac/qcoretextfontdatabase_p.h
@@ -92,6 +92,7 @@ protected:
 
 private:
     void populateFromDescriptor(CTFontDescriptorRef font, const QString &familyName = QString());
+    static QStringList fallbacksForFamily(const QString &family);
 
     mutable QString defaultFontName;