Fix font matching of typographic families on Windows

9204b8c31e broke font matching on Windows.
After this change, if you request a specific face of a family, such
as "Arial Black", and Qt detects that its typographic/preferred name
is "Arial", then it will be added as the single style of the Arial family,
which will in turn be set as populated=true.

So if you later request a regular font of "Arial" family, then it will
see that the family has already been populated, skip this step, and
then see that there is only one style available, i.e. "Arial Black".

To work around this, we need to make sure the typographic family is
properly populated the first time it is registered.

[ChangeLog][Windows][Fonts] Fixed a bug where it would be impossible
to request different faces of a font family after a specific type face
has been in use.

Task-number: QTBUG-74748
Change-Id: Ia0caace2b88a32e6114ff23ad10ee1ea8f5a3e03
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

src/gui/text/qfontdatabase.cpp

@@ -804,6 +804,13 @@ QString qt_resolveFontFamilyAlias(const QString &alias)
     return alias;
 }
 
+bool qt_isFontFamilyPopulated(const QString &familyName)
+{
+    QFontDatabasePrivate *d = privateDb();
+    QtFontFamily *f = d->family(familyName, QFontDatabasePrivate::RequestFamily);
+    return f != nullptr && f->populated;
+}
+
 /*!
     Returns a list of alternative fonts for the specified \a family and
     \a style and \a script using the \a styleHint given.

src/gui/text/qplatformfontdatabase.cpp

@@ -60,6 +60,7 @@ void qt_registerFont(const QString &familyname, const QString &stylename,
 
 void qt_registerFontFamily(const QString &familyName);
 void qt_registerAliasToFontFamily(const QString &familyName, const QString &alias);
+bool qt_isFontFamilyPopulated(const QString &familyName);
 
 /*!
     Registers the pre-rendered QPF2 font contained in the given \a dataArray.
@@ -665,6 +666,16 @@ void QPlatformFontDatabase::registerAliasToFontFamily(const QString &familyName,
     qt_registerAliasToFontFamily(familyName, alias);
 }
 
+/*!
+    Helper function that returns true if the font family has already been registered and populated.
+
+    \since 5.14
+*/
+bool QPlatformFontDatabase::isFamilyPopulated(const QString &familyName)
+{
+    return qt_isFontFamilyPopulated(familyName);
+}
+
 /*!
     \class QPlatformFontDatabase
     \since 5.0

src/gui/text/qplatformfontdatabase.h

@@ -139,6 +139,8 @@ public:
 
     static void registerFontFamily(const QString &familyName);
     static void registerAliasToFontFamily(const QString &familyName, const QString &alias);
+
+    static bool isFamilyPopulated(const QString &familyName);
 };
 
 QT_END_NAMESPACE

src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp

@@ -1012,7 +1012,8 @@ static bool addFontToDatabase(QString familyName,
                               const LOGFONT &logFont,
                               const TEXTMETRIC *textmetric,
                               const FONTSIGNATURE *signature,
-                              int type)
+                              int type,
+                              QWindowsFontDatabase *db)
 {
     // the "@family" fonts are just the same as "family". Ignore them.
     if (familyName.isEmpty() || familyName.at(0) == QLatin1Char('@') || familyName.startsWith(QLatin1String("WST_")))
@@ -1092,6 +1093,12 @@ static bool addFontToDatabase(QString familyName,
             writingSystems.setSupported(ws);
     }
 
+    // We came here from populating a different font family, so we have
+    // to ensure the entire typographic family is populated before we
+    // mark it as such inside registerFont()
+    if (!subFamilyName.isEmpty() && familyName != subFamilyName && !QPlatformFontDatabase::isFamilyPopulated(familyName))
+        db->populateFamily(familyName);
+
     QPlatformFontDatabase::registerFont(familyName, styleName, foundryName, weight,
                                         style, stretch, antialias, scalable, size, fixed, writingSystems, createFontFile(faceName));
 
@@ -1118,7 +1125,7 @@ static bool addFontToDatabase(QString familyName,
 }
 
 static int QT_WIN_CALLBACK storeFont(const LOGFONT *logFont, const TEXTMETRIC *textmetric,
-                                     DWORD type, LPARAM)
+                                     DWORD type, LPARAM lParam)
 {
     const ENUMLOGFONTEX *f = reinterpret_cast<const ENUMLOGFONTEX *>(logFont);
     const QString familyName = QString::fromWCharArray(f->elfLogFont.lfFaceName);
@@ -1130,7 +1137,7 @@ static int QT_WIN_CALLBACK storeFont(const LOGFONT *logFont, const TEXTMETRIC *t
     const FONTSIGNATURE *signature = nullptr;
     if (type & TRUETYPE_FONTTYPE)
         signature = &reinterpret_cast<const NEWTEXTMETRICEX *>(textmetric)->ntmFontSig;
-    addFontToDatabase(familyName, styleName, *logFont, textmetric, signature, type);
+    addFontToDatabase(familyName, styleName, *logFont, textmetric, signature, type, reinterpret_cast<QWindowsFontDatabase *>(lParam));
 
     // keep on enumerating
     return 1;
@@ -1149,7 +1156,7 @@ void QWindowsFontDatabase::populateFamily(const QString &familyName)
     familyName.toWCharArray(lf.lfFaceName);
     lf.lfFaceName[familyName.size()] = 0;
     lf.lfPitchAndFamily = 0;
-    EnumFontFamiliesEx(dummy, &lf, storeFont, 0, 0);
+    EnumFontFamiliesEx(dummy, &lf, storeFont, reinterpret_cast<LPARAM>(this), 0);
     ReleaseDC(0, dummy);
 }
 
@@ -1590,7 +1597,7 @@ QStringList QWindowsFontDatabase::addApplicationFont(const QByteArray &fontData,
             GetTextMetrics(hdc, &textMetrics);
 
             addFontToDatabase(familyName, styleName, lf, &textMetrics, &signatures.at(j),
-                              TRUETYPE_FONTTYPE);
+                              TRUETYPE_FONTTYPE, this);
 
             SelectObject(hdc, oldobj);
             DeleteObject(hfont);

src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_p.h

@@ -96,6 +96,8 @@ public:
     QWindowsFontDatabase();
     ~QWindowsFontDatabase() override;
 
+    void ensureFamilyPopulated(const QString &familyName);
+
     void populateFontDatabase() override;
     void populateFamily(const QString &familyName) override;
     QFontEngine *fontEngine(const QFontDef &fontDef, void *handle) override;