macOS: Fix less common writing systems on Catalina and later

Since Catalina, some fonts on macOS have been put into a special
"secret" mode where they are available, but are not enumerated:
https://support.apple.com/en-in/HT210192

It appears that this is done in order to phase the fonts out, as
the article refers to backwards-compatibility as reasoning for
keeping them around, but at the same time, there does not seem to
be any new alternatives. When using e.g. TextEdit, the text is
resolved to the "secret" font, but the font dialog does not
display it, indicating that you are using a non-existent font.

This also causes issues for Qt, since we have our own fontdatabase
and do our own matching. In order to work around it, we assume the
font is available and manually add it to the database and fallback
lists. This also appears to be what others are doing, e.g. Firefox.

[ChangeLog][macOS][Text] Fixed missing text with certain writing
systems on macOS Catalina and later.

Pick-to: 5.15 6.2 6.4
Fixes: QTBUG-96384
Fixes: QTBUG-98920
Change-Id: Ifd08ccbfdd0c06e11a44be861ad2c275c5a8e339
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

2 files changed, 138 insertions, 8 deletions

diff --git a/src/gui/text/coretext/qcoretextfontdatabase.mm b/src/gui/text/coretext/qcoretextfontdatabase.mm
index 2c16a67ffa..61c662cd45 100644
--- a/src/gui/text/coretext/qcoretextfontdatabase.mm
+++ b/src/gui/text/coretext/qcoretextfontdatabase.mm
@@ -90,6 +90,12 @@ QCoreTextFontDatabase::~QCoreTextFontDatabase()
     qDeleteAll(m_themeFonts);
 }
 
+CTFontDescriptorRef descriptorForFamily(const QString &familyName)
+{
+    return CTFontDescriptorCreateWithAttributes(CFDictionaryRef(@{
+        (id)kCTFontFamilyNameAttribute: familyName.toNSString()
+    }));
+}
 void QCoreTextFontDatabase::populateFontDatabase()
 {
     qCDebug(lcQpaFonts) << "Populating font database...";
@@ -101,6 +107,110 @@ void QCoreTextFontDatabase::populateFontDatabase()
     for (NSString *familyName in familyNames.as<const NSArray *>())
         QPlatformFontDatabase::registerFontFamily(QString::fromNSString(familyName));
 
+    // Some fonts has special handling since macOS Catalina: It is available
+    // on the platform, so that it may be used by applications directly, but does not
+    // get enumerated. Since there are no alternatives, we hardcode it.
+    if (QOperatingSystemVersion::current() >= QOperatingSystemVersion::MacOSCatalina
+            && !qEnvironmentVariableIsSet("QT_NO_HARDCODED_FALLBACK_FONTS")) {
+        m_hardcodedFallbackFonts[QChar::Script_Adlam] = QStringLiteral("Noto Sans Adlam");
+        m_hardcodedFallbackFonts[QChar::Script_Ahom] = QStringLiteral("Noto Serif Ahom");
+        m_hardcodedFallbackFonts[QChar::Script_Avestan] = QStringLiteral("Noto Sans Avestan");
+        m_hardcodedFallbackFonts[QChar::Script_Balinese] = QStringLiteral("Noto Serif Balinese");
+        m_hardcodedFallbackFonts[QChar::Script_Bamum] = QStringLiteral("Noto Sans Bamum");
+        m_hardcodedFallbackFonts[QChar::Script_BassaVah] = QStringLiteral("Noto Sans Bassa Vah");
+        m_hardcodedFallbackFonts[QChar::Script_Batak] = QStringLiteral("Noto Sans Batak");
+        m_hardcodedFallbackFonts[QChar::Script_Bhaiksuki] = QStringLiteral("Noto Sans Bhaiksuki");
+        m_hardcodedFallbackFonts[QChar::Script_Brahmi] = QStringLiteral("Noto Sans Brahmi");
+        m_hardcodedFallbackFonts[QChar::Script_Buginese] = QStringLiteral("Noto Sans Buginese");
+        m_hardcodedFallbackFonts[QChar::Script_Buhid] = QStringLiteral("Noto Sans Buhid");
+        m_hardcodedFallbackFonts[QChar::Script_Carian] = QStringLiteral("Noto Sans Carian");
+        m_hardcodedFallbackFonts[QChar::Script_CaucasianAlbanian] = QStringLiteral("Noto Sans Caucasian Albanian");
+        m_hardcodedFallbackFonts[QChar::Script_Chakma] = QStringLiteral("Noto Sans Chakma");
+        m_hardcodedFallbackFonts[QChar::Script_Cham] = QStringLiteral("Noto Sans Cham");
+        m_hardcodedFallbackFonts[QChar::Script_Coptic] = QStringLiteral("Noto Sans Coptic");
+        m_hardcodedFallbackFonts[QChar::Script_Cuneiform] = QStringLiteral("Noto Sans Cuneiform");
+        m_hardcodedFallbackFonts[QChar::Script_Cypriot] = QStringLiteral("Noto Sans Cypriot");
+        m_hardcodedFallbackFonts[QChar::Script_Duployan] = QStringLiteral("Noto Sans Duployan");
+        m_hardcodedFallbackFonts[QChar::Script_EgyptianHieroglyphs] = QStringLiteral("Noto Sans Egyptian Hieroglyphs");
+        m_hardcodedFallbackFonts[QChar::Script_Elbasan] = QStringLiteral("Noto Sans Elbasan");
+        m_hardcodedFallbackFonts[QChar::Script_Glagolitic] = QStringLiteral("Noto Sans Glagolitic");
+        m_hardcodedFallbackFonts[QChar::Script_Gothic] = QStringLiteral("Noto Sans Gothic");
+        m_hardcodedFallbackFonts[QChar::Script_HanifiRohingya] = QStringLiteral("Noto Sans Hanifi Rohingya");
+        m_hardcodedFallbackFonts[QChar::Script_Hanunoo] = QStringLiteral("Noto Sans Hanunoo");
+        m_hardcodedFallbackFonts[QChar::Script_Hatran] = QStringLiteral("Noto Sans Hatran");
+        m_hardcodedFallbackFonts[QChar::Script_ImperialAramaic] = QStringLiteral("Noto Sans Imperial Aramaic");
+        m_hardcodedFallbackFonts[QChar::Script_InscriptionalPahlavi] = QStringLiteral("Noto Sans Inscriptional Pahlavi");
+        m_hardcodedFallbackFonts[QChar::Script_InscriptionalParthian] = QStringLiteral("Noto Sans Inscriptional Parthian");
+        m_hardcodedFallbackFonts[QChar::Script_Javanese] = QStringLiteral("Noto Sans Javanese");
+        m_hardcodedFallbackFonts[QChar::Script_Kaithi] = QStringLiteral("Noto Sans Kaithi");
+        m_hardcodedFallbackFonts[QChar::Script_KayahLi] = QStringLiteral("Noto Sans Kayah Li");
+        m_hardcodedFallbackFonts[QChar::Script_Kharoshthi] = QStringLiteral("Noto Sans Kharoshthi");
+        m_hardcodedFallbackFonts[QChar::Script_Khojki] = QStringLiteral("Noto Sans Khojki");
+        m_hardcodedFallbackFonts[QChar::Script_Khudawadi] = QStringLiteral("Noto Sans Khudawadi");
+        m_hardcodedFallbackFonts[QChar::Script_Lepcha] = QStringLiteral("Noto Sans Lepcha");
+        m_hardcodedFallbackFonts[QChar::Script_Limbu] = QStringLiteral("Noto Sans Limbu");
+        m_hardcodedFallbackFonts[QChar::Script_LinearA] = QStringLiteral("Noto Sans Linear A");
+        m_hardcodedFallbackFonts[QChar::Script_LinearB] = QStringLiteral("Noto Sans Linear B");
+        m_hardcodedFallbackFonts[QChar::Script_Lisu] = QStringLiteral("Noto Sans Lisu");
+        m_hardcodedFallbackFonts[QChar::Script_Lycian] = QStringLiteral("Noto Sans Lycian");
+        m_hardcodedFallbackFonts[QChar::Script_Lydian] = QStringLiteral("Noto Sans Lydian");
+        m_hardcodedFallbackFonts[QChar::Script_Mahajani] = QStringLiteral("Noto Sans Mahajani");
+        m_hardcodedFallbackFonts[QChar::Script_Mandaic] = QStringLiteral("Noto Sans Mandaic");
+        m_hardcodedFallbackFonts[QChar::Script_Manichaean] = QStringLiteral("Noto Sans Manichaean");
+        m_hardcodedFallbackFonts[QChar::Script_Marchen] = QStringLiteral("Noto Sans Marchen");
+        m_hardcodedFallbackFonts[QChar::Script_MendeKikakui] = QStringLiteral("Noto Sans Mende Kikakui");
+        m_hardcodedFallbackFonts[QChar::Script_MeroiticCursive] = QStringLiteral("Noto Sans Meroitic");
+        m_hardcodedFallbackFonts[QChar::Script_MeroiticHieroglyphs] = QStringLiteral("Noto Sans Meroitic");
+        m_hardcodedFallbackFonts[QChar::Script_Miao] = QStringLiteral("Noto Sans Miao");
+        m_hardcodedFallbackFonts[QChar::Script_Modi] = QStringLiteral("Noto Sans Modi");
+        m_hardcodedFallbackFonts[QChar::Script_Mongolian] = QStringLiteral("Noto Sans Mongolian");
+        m_hardcodedFallbackFonts[QChar::Script_Mro] = QStringLiteral("Noto Sans Mro");
+        m_hardcodedFallbackFonts[QChar::Script_MeeteiMayek] = QStringLiteral("Noto Sans Meetei Mayek");
+        m_hardcodedFallbackFonts[QChar::Script_Multani] = QStringLiteral("Noto Sans Multani");
+        m_hardcodedFallbackFonts[QChar::Script_Nabataean] = QStringLiteral("Noto Sans Nabataean");
+        m_hardcodedFallbackFonts[QChar::Script_Newa] = QStringLiteral("Noto Sans Newa");
+        m_hardcodedFallbackFonts[QChar::Script_NewTaiLue] = QStringLiteral("Noto Sans New Tai Lue");
+        m_hardcodedFallbackFonts[QChar::Script_Nko] = QStringLiteral("Noto Sans Nko");
+        m_hardcodedFallbackFonts[QChar::Script_OlChiki] = QStringLiteral("Noto Sans Ol Chiki");
+        m_hardcodedFallbackFonts[QChar::Script_OldHungarian] = QStringLiteral("Noto Sans Old Hungarian");
+        m_hardcodedFallbackFonts[QChar::Script_OldItalic] = QStringLiteral("Noto Sans Old Italic");
+        m_hardcodedFallbackFonts[QChar::Script_OldNorthArabian] = QStringLiteral("Noto Sans Old North Arabian");
+        m_hardcodedFallbackFonts[QChar::Script_OldPermic] = QStringLiteral("Noto Sans Old Permic");
+        m_hardcodedFallbackFonts[QChar::Script_OldPersian] = QStringLiteral("Noto Sans Old Persian");
+        m_hardcodedFallbackFonts[QChar::Script_OldSouthArabian] = QStringLiteral("Noto Sans Old South Arabian");
+        m_hardcodedFallbackFonts[QChar::Script_OldTurkic] = QStringLiteral("Noto Sans Old Turkic");
+        m_hardcodedFallbackFonts[QChar::Script_Osage] = QStringLiteral("Noto Sans Osage");
+        m_hardcodedFallbackFonts[QChar::Script_Osmanya] = QStringLiteral("Noto Sans Osmanya");
+        m_hardcodedFallbackFonts[QChar::Script_PahawhHmong] = QStringLiteral("Noto Sans Pahawh Hmong");
+        m_hardcodedFallbackFonts[QChar::Script_Palmyrene] = QStringLiteral("Noto Sans Palmyrene");
+        m_hardcodedFallbackFonts[QChar::Script_PauCinHau] = QStringLiteral("Noto Sans Pau Cin Hau");
+        m_hardcodedFallbackFonts[QChar::Script_PhagsPa] = QStringLiteral("Noto Sans PhagsPa");
+        m_hardcodedFallbackFonts[QChar::Script_Phoenician] = QStringLiteral("Noto Sans Phoenician");
+        m_hardcodedFallbackFonts[QChar::Script_PsalterPahlavi] = QStringLiteral("Noto Sans Psalter Pahlavi");
+        m_hardcodedFallbackFonts[QChar::Script_Rejang] = QStringLiteral("Noto Sans Rejang");
+        m_hardcodedFallbackFonts[QChar::Script_Samaritan] = QStringLiteral("Noto Sans Samaritan");
+        m_hardcodedFallbackFonts[QChar::Script_Saurashtra] = QStringLiteral("Noto Sans Saurashtra");
+        m_hardcodedFallbackFonts[QChar::Script_Sharada] = QStringLiteral("Noto Sans Sharada");
+        m_hardcodedFallbackFonts[QChar::Script_Siddham] = QStringLiteral("Noto Sans Siddham");
+        m_hardcodedFallbackFonts[QChar::Script_SoraSompeng] = QStringLiteral("Noto Sans Sora Sompeng");
+        m_hardcodedFallbackFonts[QChar::Script_Sundanese] = QStringLiteral("Noto Sans Sundanese");
+        m_hardcodedFallbackFonts[QChar::Script_SylotiNagri] = QStringLiteral("Noto Sans Syloti Nagri");
+        m_hardcodedFallbackFonts[QChar::Script_Tagalog] = QStringLiteral("Noto Sans Tagalog");
+        m_hardcodedFallbackFonts[QChar::Script_Tagbanwa] = QStringLiteral("Noto Sans Tagbanwa");
+        m_hardcodedFallbackFonts[QChar::Script_Takri] = QStringLiteral("Noto Sans Takri");
+        m_hardcodedFallbackFonts[QChar::Script_TaiLe] = QStringLiteral("Noto Sans Tai Le");
+        m_hardcodedFallbackFonts[QChar::Script_TaiTham] = QStringLiteral("Noto Sans Tai Tham");
+        m_hardcodedFallbackFonts[QChar::Script_TaiViet] = QStringLiteral("Noto Sans Tai Viet");
+        m_hardcodedFallbackFonts[QChar::Script_Thaana] = QStringLiteral("Noto Sans Thaana");
+        m_hardcodedFallbackFonts[QChar::Script_Tifinagh] = QStringLiteral("Noto Sans Tifinagh");
+        m_hardcodedFallbackFonts[QChar::Script_Tirhuta] = QStringLiteral("Noto Sans Tirhuta");
+        m_hardcodedFallbackFonts[QChar::Script_Ugaritic] = QStringLiteral("Noto Sans Ugaritic");
+        m_hardcodedFallbackFonts[QChar::Script_Vai] = QStringLiteral("Noto Sans Vai");
+        m_hardcodedFallbackFonts[QChar::Script_WarangCiti] = QStringLiteral("Noto Sans Warang Citi");
+        m_hardcodedFallbackFonts[QChar::Script_Wancho] = QStringLiteral("Noto Sans Wancho");
+        m_hardcodedFallbackFonts[QChar::Script_Yi] = QStringLiteral("Noto Sans Yi");
+    }
+
     qCDebug(lcQpaFonts) << "Populating available families took" << elapsed.restart() << "ms";
 
     populateThemeFonts();
@@ -174,13 +284,6 @@ bool QCoreTextFontDatabase::populateFamilyAliases(const QString &missingFamily)
 #endif
 }
 
-CTFontDescriptorRef descriptorForFamily(const QString &familyName)
-{
-    return CTFontDescriptorCreateWithAttributes(CFDictionaryRef(@{
-        (id)kCTFontFamilyNameAttribute: familyName.toNSString()
-    }));
-}
-
 CTFontDescriptorRef descriptorForFamily(const char *familyName)
 {
     return descriptorForFamily(QString::fromLatin1(familyName));
@@ -570,6 +673,31 @@ QStringList QCoreTextFontDatabase::fallbacksForFamily(const QString &family, QFo
     // add Apple Symbols to cover those too.
     if (!fallbackList.contains(QStringLiteral("Apple Symbols")))
         fallbackList.append(QStringLiteral("Apple Symbols"));
+    // Some Noto* fonts are not automatically enumerated by system, despite being the main
+    // fonts for their writing system.
+    QString hardcodedFont = m_hardcodedFallbackFonts.value(script);
+    if (!hardcodedFont.isEmpty() && !fallbackList.contains(hardcodedFont)) {
+        if (!isFamilyPopulated(hardcodedFont)) {
+            if (!m_privateFamilies.contains(hardcodedFont)) {
+                QCFType<CTFontDescriptorRef> familyDescriptor = descriptorForFamily(hardcodedFont);
+                QCFType<CFArrayRef> matchingFonts = CTFontDescriptorCreateMatchingFontDescriptors(familyDescriptor, nullptr);
+                if (matchingFonts) {
+                    const int numFonts = CFArrayGetCount(matchingFonts);
+                    for (int i = 0; i < numFonts; ++i)
+                        const_cast<QCoreTextFontDatabase *>(this)->populateFromDescriptor(CTFontDescriptorRef(CFArrayGetValueAtIndex(matchingFonts, i)),
+                                                                                          hardcodedFont);
+
+                    fallbackList.append(hardcodedFont);
+                }
+
+                // Register as private family even if the font is not found, in order to avoid
+                // redoing the check later. In later calls, the font will then just be ignored.
+                m_privateFamilies.insert(hardcodedFont);
+            }
+        } else {
+            fallbackList.append(hardcodedFont);
+        }
+    }
 #endif
 
     extern QStringList qt_sort_families_by_writing_system(QChar::Script, const QStringList &);
@@ -620,7 +748,7 @@ QStringList QCoreTextFontDatabase::addApplicationFont(const QByteArray &fontData
 
 bool QCoreTextFontDatabase::isPrivateFontFamily(const QString &family) const
 {
-    if (family.startsWith(u'.') || family == "LastResort"_L1)
+    if (family.startsWith(u'.') || family == "LastResort"_L1 || m_privateFamilies.contains(family))
         return true;
 
     return QPlatformFontDatabase::isPrivateFontFamily(family);
diff --git a/src/gui/text/coretext/qcoretextfontdatabase_p.h b/src/gui/text/coretext/qcoretextfontdatabase_p.h
index ea3a094247..74c3f30b79 100644
--- a/src/gui/text/coretext/qcoretextfontdatabase_p.h
+++ b/src/gui/text/coretext/qcoretextfontdatabase_p.h
@@ -57,6 +57,8 @@ private:
 
     QHash<QPlatformTheme::Font, QFont *> m_themeFonts;
     QHash<QString, QList<QCFType<CTFontDescriptorRef>>> m_systemFontDescriptors;
+    QHash<QChar::Script, QString> m_hardcodedFallbackFonts;
+    mutable QSet<QString> m_privateFamilies;
 
     bool m_hasPopulatedAliases;