Keep Multi font engine in QFontCache

If we only keep single QFontEngineFT in QFontCache, then when we
are looking for the MultiQPA next time with the same QFontDef,
the FT engine will be returned and we get no font fallback support.
That's why we need to keep the Multi engines in QFontCache as well
and distinguish them from the single item. Since QPA doesn't use
'screen' field of QFontCache::Key structure, we use it here to
indicate that we are caching a multi font engine.

Change-Id: Id899d5c5ba52f4bccf134bcd6b1c6386ba22063c
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>

3 files changed, 16 insertions, 7 deletions

diff --git a/src/gui/text/qfontdatabase.h b/src/gui/text/qfontdatabase.h
index 6e0550334f..873d00946c 100644
--- a/src/gui/text/qfontdatabase.h
+++ b/src/gui/text/qfontdatabase.h
@@ -153,7 +153,7 @@ private:
     static void createDatabase();
     static void parseFontName(const QString &name, QString &foundry, QString &family);
     static QString resolveFontFamilyAlias(const QString &family);
-    static QFontEngine *findFont(int script, const QFontPrivate *fp, const QFontDef &request);
+    static QFontEngine *findFont(int script, const QFontPrivate *fp, const QFontDef &request, bool multi = false);
     static void load(const QFontPrivate *d, int script);
 
     friend struct QFontDef;
diff --git a/src/gui/text/qfontdatabase_qpa.cpp b/src/gui/text/qfontdatabase_qpa.cpp
index 4cd47da6b7..95a0aff261 100644
--- a/src/gui/text/qfontdatabase_qpa.cpp
+++ b/src/gui/text/qfontdatabase_qpa.cpp
@@ -178,6 +178,11 @@ QFontEngine *loadEngine(int script, const QFontDef &request,
             fallbacks = family->fallbackFamilies;
 
         engine = new QFontEngineMultiQPA(engine, script, fallbacks);
+
+        // Cache Multi font engine as well in case we got the FT single
+        // font engine when we are actually looking for a Multi one
+        QFontCache::Key key(request, script, 1);
+        QFontCache::instance()->instance()->insertEngine(key, engine);
     }
 
     return engine;
@@ -230,7 +235,7 @@ bool QFontDatabase::supportsThreadedFontRendering()
 */
 QFontEngine *
 QFontDatabase::findFont(int script, const QFontPrivate *fp,
-                        const QFontDef &request)
+                        const QFontDef &request, bool multi)
 {
     QMutexLocker locker(fontDatabaseMutex());
 
@@ -240,7 +245,7 @@ QFontDatabase::findFont(int script, const QFontPrivate *fp,
         initializeDb();
 
     QFontEngine *engine;
-    QFontCache::Key key(request, script);
+    QFontCache::Key key(request, script, multi ? 1 : 0);
     engine = QFontCache::instance()->findEngine(key);
     if (engine) {
         qDebug() << "Cache hit level 1";
@@ -282,7 +287,7 @@ QFontDatabase::findFont(int script, const QFontPrivate *fp,
             for (int i = 0; !engine && i < fallbacks.size(); i++) {
                 QFontDef def = request;
                 def.family = fallbacks.at(i);
-                QFontCache::Key key(def,script);
+                QFontCache::Key key(def, script, multi ? 1 : 0);
                 engine = QFontCache::instance()->findEngine(key);
                 if (!engine) {
                     QtFontDesc desc;
@@ -328,7 +333,11 @@ void QFontDatabase::load(const QFontPrivate *d, int script)
     if (req.stretch == 0)
         req.stretch = 100;
 
-    QFontCache::Key key(req, script);
+    // Until we specifically asked not to, try looking for Multi font engine
+    // first, the last '1' indicates that we want Multi font engine instead
+    // of single ones
+    bool multi = !(req.styleStrategy & QFont::NoFontMerging);
+    QFontCache::Key key(req, script, multi ? 1 : 0);
 
     if (!d->engineData)
         getEngineData(d, key);
@@ -359,7 +368,7 @@ void QFontDatabase::load(const QFontPrivate *d, int script)
     for (; !fe && it != end; ++it) {
         req.family = *it;
 
-        fe = QFontDatabase::findFont(script, d, req);
+        fe = QFontDatabase::findFont(script, d, req, multi);
         if (fe && (fe->type()==QFontEngine::Box) && !req.family.isEmpty())
             fe = 0;
     }
diff --git a/src/gui/text/qfontengine_qpa.cpp b/src/gui/text/qfontengine_qpa.cpp
index 7c09ae7cf8..c25ed43fdc 100644
--- a/src/gui/text/qfontengine_qpa.cpp
+++ b/src/gui/text/qfontengine_qpa.cpp
@@ -680,7 +680,7 @@ void QFontEngineMultiQPA::loadEngine(int at)
     request.family = fallbackFamilies.at(at-1);
     engines[at] = QFontDatabase::findFont(script,
                                           /*fontprivate*/0,
-                                          request);
+                                          request, false);
     Q_ASSERT(engines[at]);
     engines[at]->ref.ref();
     engines[at]->fontDef = request;