1 files changed, 31 insertions, 11 deletions

diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index f2fd585835..a43af37097 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -597,7 +597,32 @@ Q_GUI_EXPORT int qt_script_for_writing_system(QFontDatabase::WritingSystem writi
 }
 
 
+/*!
+    \internal
+
+    Tests if the given family \a family supports writing system \a writingSystem,
+    including the special case for Han script mapping to several subsequent writing systems
+*/
+static bool familySupportsWritingSystem(QtFontFamily *family, size_t writingSystem)
+{
+    Q_ASSERT(family != nullptr);
+    Q_ASSERT(writingSystem != QFontDatabase::Any && writingSystem < QFontDatabase::WritingSystemsCount);
+
+    size_t ws = writingSystem;
+    do {
+        if ((family->writingSystems[ws] & QtFontFamily::Supported) != 0)
+            return true;
+    } while (writingSystem >= QFontDatabase::SimplifiedChinese && writingSystem <= QFontDatabase::Japanese && ++ws <= QFontDatabase::Japanese);
+
+    return false;
+}
 
+Q_GUI_EXPORT QFontDatabase::WritingSystem qt_writing_system_for_script(int script)
+{
+    return QFontDatabase::WritingSystem(std::find(scriptForWritingSystem,
+                                                  scriptForWritingSystem + QFontDatabase::WritingSystemsCount,
+                                                  script) - scriptForWritingSystem);
+}
 
 /*!
   \internal
@@ -814,9 +839,7 @@ QStringList QPlatformFontDatabase::fallbacksForFamily(const QString &family, QFo
     QStringList preferredFallbacks;
     QStringList otherFallbacks;
 
-    size_t writingSystem = std::find(scriptForWritingSystem,
-                                     scriptForWritingSystem + QFontDatabase::WritingSystemsCount,
-                                     script) - scriptForWritingSystem;
+    auto writingSystem = qt_writing_system_for_script(script);
     if (writingSystem >= QFontDatabase::WritingSystemsCount)
         writingSystem = QFontDatabase::Any;
 
@@ -826,7 +849,7 @@ QStringList QPlatformFontDatabase::fallbacksForFamily(const QString &family, QFo
 
         f->ensurePopulated();
 
-        if (writingSystem > QFontDatabase::Any && f->writingSystems[writingSystem] != QtFontFamily::Supported)
+        if (writingSystem != QFontDatabase::Any && !familySupportsWritingSystem(f, writingSystem))
             continue;
 
         for (int j = 0; j < f->count; ++j) {
@@ -1253,8 +1276,7 @@ static int match(int script, const QFontDef &request,
 
     load(family_name, script);
 
-    size_t writingSystem = std::find(scriptForWritingSystem, scriptForWritingSystem +
-            QFontDatabase::WritingSystemsCount, script) - scriptForWritingSystem;
+    auto writingSystem = qt_writing_system_for_script(script);
     if (writingSystem >= QFontDatabase::WritingSystemsCount)
         writingSystem = QFontDatabase::Any;
 
@@ -1271,7 +1293,7 @@ static int match(int script, const QFontDef &request,
         test.family->ensurePopulated();
 
         // Check if family is supported in the script we want
-        if (writingSystem != QFontDatabase::Any && !(test.family->writingSystems[writingSystem] & QtFontFamily::Supported))
+        if (writingSystem != QFontDatabase::Any && !familySupportsWritingSystem(test.family, writingSystem))
             continue;
 
         // as we know the script is supported, we can be sure
@@ -2857,9 +2879,7 @@ QString QFontDatabase::resolveFontFamilyAlias(const QString &family)
 
 Q_GUI_EXPORT QStringList qt_sort_families_by_writing_system(QChar::Script script, const QStringList &families)
 {
-    size_t writingSystem = std::find(scriptForWritingSystem,
-                                     scriptForWritingSystem + QFontDatabase::WritingSystemsCount,
-                                     script) - scriptForWritingSystem;
+    size_t writingSystem = qt_writing_system_for_script(script);
     if (writingSystem == QFontDatabase::Any
             || writingSystem >= QFontDatabase::WritingSystemsCount) {
         return families;
@@ -2881,7 +2901,7 @@ Q_GUI_EXPORT QStringList qt_sort_families_by_writing_system(QChar::Script script
 
         uint order = i;
         if (testFamily == nullptr
-              || (testFamily->writingSystems[writingSystem] & QtFontFamily::Supported) == 0) {
+              || !familySupportsWritingSystem(testFamily, writingSystem)) {
             order |= 1u << 31;
         }