From f29e38f9a433ce7e47eb9ec88927b184c856dd6d Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@digia.com>
Date: Wed, 27 Nov 2013 16:32:28 +0100
Subject: 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>
---
 src/gui/text/qfontdatabase.cpp     | 15 +++++++++------
 src/gui/text/qfontdatabase_qpa.cpp | 30 ++++++++++++++++++++----------
 2 files changed, 29 insertions(+), 16 deletions(-)

(limited to 'src')

diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index ff050d1758..24288489c6 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -562,9 +562,9 @@ struct QtFontDesc
     int familyIndex;
 };
 
-static void match(int script, const QFontDef &request,
-                  const QString &family_name, const QString &foundry_name, int force_encoding_id,
-                  QtFontDesc *desc, const QList<int> &blacklistedFamilies = QList<int>());
+static int match(int script, const QFontDef &request,
+                 const QString &family_name, const QString &foundry_name, int force_encoding_id,
+                 QtFontDesc *desc, const QList<int> &blacklisted);
 
 static void initFontDef(const QtFontDesc &desc, const QFontDef &request, QFontDef *fontDef, bool multi)
 {
@@ -846,11 +846,12 @@ static bool matchFamilyName(const QString &familyName, QtFontFamily *f)
 
     Tries to find the best match for a given request and family/foundry
 */
-static void match(int script, const QFontDef &request,
-                  const QString &family_name, const QString &foundry_name, int force_encoding_id,
-                  QtFontDesc *desc, const QList<int> &blacklistedFamilies)
+static int match(int script, const QFontDef &request,
+                 const QString &family_name, const QString &foundry_name, int force_encoding_id,
+                 QtFontDesc *desc, const QList<int> &blacklistedFamilies)
 {
     Q_UNUSED(force_encoding_id);
+    int result = -1;
 
     QtFontStyle::Key styleKey;
     styleKey.style = request.style;
@@ -925,12 +926,14 @@ static void match(int script, const QFontDef &request,
         newscore += score_adjust;
 
         if (newscore < score) {
+            result = x;
             score = newscore;
             *desc = test;
         }
         if (newscore < 10) // xlfd instead of FT... just accept it
             break;
     }
+    return result;
 }
 
 static QString styleStringHelper(int weight, QFont::Style style)
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);
                 }
             }
         }
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