Fix font lookup.

Change match() to return an index and use that to reintroduce
the blacklist bookkeeping for fonts for which font engine
creation fails (for example, due to missing open type support).
Change the algorithm to retry search if that happens.
Add empty string as fallback for non-common scripts indicating
'try to find any font matching the script' as is done in Qt 4.

Task-number: QTBUG-34908
Change-Id: I9ac81ff1c275ebb635675dc26b52394789fca60c
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 20 insertions, 10 deletions

diff --git a/src/gui/text/qfontdatabase_qpa.cpp b/src/gui/text/qfontdatabase_qpa.cpp
index fddbb11122..98e89a8327 100644
--- a/src/gui/text/qfontdatabase_qpa.cpp
+++ b/src/gui/text/qfontdatabase_qpa.cpp
@@ -306,9 +306,12 @@ QFontDatabase::findFont(int script, const QFontPrivate *fp,
     }
 
     QtFontDesc desc;
-    match(script, request, family_name, foundry_name, force_encoding_id, &desc);
-    if (desc.family != 0 && desc.foundry != 0 && desc.style != 0) {
+    QList<int> blackListed;
+    int index = match(script, request, family_name, foundry_name, force_encoding_id, &desc, blackListed);
+    if (index >= 0) {
         engine = loadEngine(script, request, desc.family, desc.foundry, desc.style, desc.size);
+        if (!engine)
+            blackListed.append(index);
     } else {
         FM_DEBUG("  NO MATCH FOUND\n");
     }
@@ -332,6 +335,8 @@ QFontDatabase::findFont(int script, const QFontPrivate *fp,
                                                      QFont::Style(request.style),
                                                      QFont::StyleHint(request.styleHint),
                                                      QChar::Script(script));
+            if (script > QChar::Script_Common)
+                fallbacks += QString(); // Find the first font matching the specified script.
 
             for (int i = 0; !engine && i < fallbacks.size(); i++) {
                 QFontDef def = request;
@@ -340,14 +345,19 @@ QFontDatabase::findFont(int script, const QFontPrivate *fp,
                 engine = QFontCache::instance()->findEngine(key);
                 if (!engine) {
                     QtFontDesc desc;
-                    match(script, def, def.family, QLatin1String(""), 0, &desc);
-                    if (desc.family == 0 && desc.foundry == 0 && desc.style == 0) {
-                        continue;
-                    }
-                    engine = loadEngine(script, def, desc.family, desc.foundry, desc.style, desc.size);
-                    if (engine) {
-                        initFontDef(desc, def, &engine->fontDef, engine->type() == QFontEngine::Multi);
-                    }
+                    do {
+                        index = match(script, def, def.family, QLatin1String(""), 0, &desc, blackListed);
+                        if (index >= 0) {
+                            QFontDef loadDef = def;
+                            if (loadDef.family.isEmpty())
+                                loadDef.family = desc.family->name;
+                            engine = loadEngine(script, loadDef, desc.family, desc.foundry, desc.style, desc.size);
+                            if (engine)
+                                initFontDef(desc, loadDef, &engine->fontDef, engine->type() == QFontEngine::Multi);
+                            else
+                                blackListed.append(index);
+                        }
+                    } while (index >= 0 && !engine);
                 }
             }
         }