Resolve font alias before testing for exact matching

It is required in X11 for resolving some default substitutions
like 'sans', 'serif', etc. It also provides stub to implement
similar replacement in other platforms like Windows.

Task-number: QTBUG-15575
Reviewed-by: Eskil

4 files changed, 32 insertions, 0 deletions

diff --git a/src/gui/text/qfont.cpp b/src/gui/text/qfont.cpp
index 084b7ac..64eb27a 100644
--- a/src/gui/text/qfont.cpp
+++ b/src/gui/text/qfont.cpp
@@ -139,6 +139,9 @@ bool QFontDef::exactMatch(const QFontDef &other) const
     QFontDatabase::parseFontName(family, this_foundry, this_family);
     QFontDatabase::parseFontName(other.family, other_foundry, other_family);
 
+    this_family = QFontDatabase::resolveFontFamilyAlias(this_family);
+    other_family = QFontDatabase::resolveFontFamilyAlias(other_family);
+
     return (styleHint     == other.styleHint
             && styleStrategy == other.styleStrategy
             && weight        == other.weight
diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index 8e92b1a..1e94bf5 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -1087,6 +1087,12 @@ QT_BEGIN_INCLUDE_NAMESPACE
 #elif defined(Q_OS_SYMBIAN)
 #  include "qfontdatabase_s60.cpp"
 #endif
+#if !defined(Q_WS_X11)
+QString QFontDatabase::resolveFontFamilyAlias(const QString &family)
+{
+    return family;
+}
+#endif
 QT_END_INCLUDE_NAMESPACE
 
 static QtFontStyle *bestStyle(QtFontFoundry *foundry, const QtFontStyle::Key &styleKey)
diff --git a/src/gui/text/qfontdatabase.h b/src/gui/text/qfontdatabase.h
index 3e9483b..ae1130e 100644
--- a/src/gui/text/qfontdatabase.h
+++ b/src/gui/text/qfontdatabase.h
@@ -152,6 +152,7 @@ public:
 private:
     static void createDatabase();
     static void parseFontName(const QString &name, QString &foundry, QString &family);
+    static QString resolveFontFamilyAlias(const QString &family);
 #if defined(Q_WS_QWS) || defined(Q_WS_QPA) || defined(Q_OS_SYMBIAN)
     static QFontEngine *findFont(int script, const QFontPrivate *fp, const QFontDef &request);
 #endif
diff --git a/src/gui/text/qfontdatabase_x11.cpp b/src/gui/text/qfontdatabase_x11.cpp
index f923d87..02b0148 100644
--- a/src/gui/text/qfontdatabase_x11.cpp
+++ b/src/gui/text/qfontdatabase_x11.cpp
@@ -2120,4 +2120,26 @@ bool QFontDatabase::supportsThreadedFontRendering()
 #endif
 }
 
+QString QFontDatabase::resolveFontFamilyAlias(const QString &family)
+{
+#if defined(QT_NO_FONTCONFIG)
+    return family;
+#else
+    FcPattern *pattern = FcPatternCreate();
+    if (!pattern)
+        return family;
+
+    FcPatternAddString(pattern, FC_FAMILY, (const FcChar8 *) family.toUtf8().data());
+    FcConfigSubstitute(0, pattern, FcMatchPattern);
+    FcDefaultSubstitute(pattern);
+
+    FcChar8 *familyAfterSubstitution;
+    FcPatternGetString(pattern, FC_FAMILY, 0, &familyAfterSubstitution);
+    QString resolved = QString::fromUtf8((const char *) familyAfterSubstitution);
+    FcPatternDestroy(pattern);
+
+    return resolved;
+#endif
+}
+
 QT_END_NAMESPACE