Fix QFontconfigDatabase unable to fallback to a localized family

When populating the font database, FcPatternGetString(FC_FAMILY) gets
a localized font family name; but, in fallbacksForFamily, it gets
a non-localized font family name, so it unable to find the proper font to fallback.
Simply register all family name variants as aliases to localized name
and make sure they are checked when getting fallback families.

Task-number: QTBUG-28806
Task-number: QTBUG-30415

Change-Id: I71c03ae9b51a28736c2576f3442f1bbdb3497c09
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: jian liang <jianliang79@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

3 files changed, 13 insertions, 15 deletions

diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index e3270b430f..86a5bed15d 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -344,6 +344,7 @@ struct  QtFontFamily
     bool askedForFallback;
     unsigned char writingSystems[QFontDatabase::WritingSystemsCount];
 
+    bool matchesFamilyName(const QString &familyName) const;
     QtFontFoundry *foundry(const QString &f, bool = false);
 };
 
@@ -383,6 +384,11 @@ QtFontFoundry *QtFontFamily::foundry(const QString &f, bool create)
     return foundries[count++];
 }
 
+bool QtFontFamily::matchesFamilyName(const QString &familyName) const
+{
+    return name.compare(familyName, Qt::CaseInsensitive) == 0 || aliases.contains(familyName, Qt::CaseInsensitive);
+}
+
 
 class QFontDatabasePrivate
 {
@@ -852,19 +858,7 @@ static bool matchFamilyName(const QString &familyName, QtFontFamily *f)
 {
     if (familyName.isEmpty())
         return true;
-
-    if (f->name.compare(familyName, Qt::CaseInsensitive) == 0)
-        return true;
-
-    QStringList::const_iterator it = f->aliases.constBegin();
-    while (it != f->aliases.constEnd()) {
-        if ((*it).compare(familyName, Qt::CaseInsensitive) == 0)
-            return true;
-
-        ++it;
-    }
-
-    return false;
+    return f->matchesFamilyName(familyName);
 }
 
 /*!
diff --git a/src/gui/text/qfontdatabase_qpa.cpp b/src/gui/text/qfontdatabase_qpa.cpp
index be42e892fa..32580ada7a 100644
--- a/src/gui/text/qfontdatabase_qpa.cpp
+++ b/src/gui/text/qfontdatabase_qpa.cpp
@@ -110,8 +110,7 @@ static QStringList fallbackFamilies(const QString &family, QFont::Style style, Q
     for (i = retList.begin(); i != retList.end(); ++i) {
         bool contains = false;
         for (int j = 0; j < db->count; j++) {
-            QtFontFamily *qtFamily = db->families[j];
-            if (!(i->compare(qtFamily->name,Qt::CaseInsensitive))) {
+            if (db->families[j]->matchesFamilyName(*i)) {
                 contains = true;
                 break;
             }
diff --git a/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp b/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
index 6ba71d112e..0d57b71f46 100644
--- a/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
+++ b/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
@@ -370,6 +370,8 @@ static bool isSymbolFont(FontFile *fontFile)
     return hasSymbolMap;
 }
 
+Q_GUI_EXPORT void qt_registerAliasToFontFamily(const QString &familyName, const QString &alias);
+
 void QFontconfigDatabase::populateFontDatabase()
 {
     FcFontSet  *fonts;
@@ -511,6 +513,9 @@ void QFontconfigDatabase::populateFontDatabase()
         QString styleName = style_value ? QString::fromUtf8((const char *) style_value) : QString();
         QPlatformFontDatabase::registerFont(familyName,styleName,QLatin1String((const char *)foundry_value),weight,style,stretch,antialias,scalable,pixel_size,fixedPitch,writingSystems,fontFile);
 //        qDebug() << familyName << (const char *)foundry_value << weight << style << &writingSystems << scalable << true << pixel_size;
+
+        for (int k = 1; FcPatternGetString(fonts->fonts[i], FC_FAMILY, k, &value) == FcResultMatch; ++k)
+            qt_registerAliasToFontFamily(familyName, QString::fromUtf8((const char *)value));
     }
 
     FcFontSetDestroy (fonts);