Support variable applications fonts with DirectWrite

For GDI, there doesn't seem to be any way to do this, so it depends
on selecting the DirectWrite font database explicitly.

This moves the supportsVariableApplicationFonts() check into the
QPlatformFontDatabase instead of the font engine, since that's
where it belongs.

[ChangeLog][Fonts] Added support for selecting named instances in
variable application fonts when using the DirectWrite backend.

Task-number: QTBUG-108624
Change-Id: I51e0fedd7a9616088a06453a1d17f48bd18fa5a7
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

src/gui/text/freetype/qfontengine_ft.cpp

@@ -2241,15 +2241,6 @@ Qt::HANDLE QFontEngineFT::handle() const
     return non_locked_face();
 }
 
-bool QFontEngineFT::supportsVariableApplicationFonts() const
-{
-#if (FREETYPE_MAJOR*10000 + FREETYPE_MINOR*100 + FREETYPE_PATCH) >= 20900
-    return true;
-#else
-    return false;
-#endif
-}
-
 QT_END_NAMESPACE
 
 #endif // QT_NO_FREETYPE

src/gui/text/freetype/qfontengine_ft_p.h

@@ -159,8 +159,6 @@ private:
         return supportsHorizontalSubPixelPositions();
     }
 
-    bool supportsVariableApplicationFonts() const override;
-
     bool getSfntTableData(uint tag, uchar *buffer, uint *length) const override;
     int synthesized() const override;
 

src/gui/text/freetype/qfreetypefontdatabase.cpp

@@ -335,4 +335,13 @@ QStringList QFreeTypeFontDatabase::addTTFile(const QByteArray &fontData, const Q
     return families;
 }
 
+bool QFreeTypeFontDatabase::supportsVariableApplicationFonts() const
+{
+#if (FREETYPE_MAJOR*10000 + FREETYPE_MINOR*100 + FREETYPE_PATCH) >= 20900
+    return true;
+#else
+    return false;
+#endif
+}
+
 QT_END_NAMESPACE

src/gui/text/freetype/qfreetypefontdatabase_p.h

@@ -42,6 +42,7 @@ public:
     QFontEngine *fontEngine(const QByteArray &fontData, qreal pixelSize, QFont::HintingPreference hintingPreference) override;
     QStringList addApplicationFont(const QByteArray &fontData, const QString &fileName, QFontDatabasePrivate::ApplicationFont *applicationFont = nullptr) override;
     void releaseHandle(void *handle) override;
+    bool supportsVariableApplicationFonts() const override;
 
     static void addNamedInstancesForFace(void *face, int faceIndex,
                                          const QString &family, const QString &styleName,

src/gui/text/qfontengine.cpp

@@ -247,11 +247,6 @@ bool QFontEngine::supportsTransformation(const QTransform &transform) const
     return transform.type() < QTransform::TxProject;
 }
 
-bool QFontEngine::supportsVariableApplicationFonts() const
-{
-    return false;
-}
-
 bool QFontEngine::expectsGammaCorrectedBlending() const
 {
     return true;

src/gui/text/qfontengine_p.h

@@ -213,7 +213,6 @@ public:
 
     inline bool canRender(uint ucs4) const { return glyphIndex(ucs4) != 0; }
     virtual bool canRender(const QChar *str, int len) const;
-    virtual bool supportsVariableApplicationFonts() const;
 
     virtual bool supportsTransformation(const QTransform &transform) const;
 

src/gui/text/qplatformfontdatabase.cpp

@@ -645,6 +645,18 @@ bool QPlatformFontDatabase::isFamilyPopulated(const QString &familyName)
     return qt_isFontFamilyPopulated(familyName);
 }
 
+/*!
+    Returns true if this font database supports loading named instances from variable application
+    fonts.
+
+    \since 6.7
+*/
+bool QPlatformFontDatabase::supportsVariableApplicationFonts() const
+{
+    return false;
+}
+
+
 /*!
     \class QPlatformFontDatabase
     \since 5.0

src/gui/text/qplatformfontdatabase.h

@@ -89,6 +89,8 @@ public:
     virtual bool fontsAlwaysScalable() const;
     virtual QList<int> standardSizes() const;
 
+    virtual bool supportsVariableApplicationFonts() const;
+
     // helper
     static QSupportedWritingSystems writingSystemsFromTrueTypeBits(quint32 unicodeRange[4], quint32 codePageRange[2]);
     static QSupportedWritingSystems writingSystemsFromOS2Table(const char *os2Table, size_t length);

src/gui/text/unix/qfontconfigdatabase.cpp

@@ -1042,4 +1042,13 @@ void QFontconfigDatabase::setupFontEngine(QFontEngineFT *engine, const QFontDef
     engine->glyphFormat = format;
 }
 
+bool QFontconfigDatabase::supportsVariableApplicationFonts() const
+{
+#if (FREETYPE_MAJOR*10000 + FREETYPE_MINOR*100 + FREETYPE_PATCH) >= 20900
+    return true;
+#else
+    return false;
+#endif
+}
+
 QT_END_NAMESPACE

src/gui/text/unix/qfontconfigdatabase_p.h

@@ -28,6 +28,7 @@ public:
     ~QFontconfigDatabase() override;
     void populateFontDatabase() override;
     void invalidate() override;
+    bool supportsVariableApplicationFonts() const override;
     QFontEngineMulti *fontEngineMulti(QFontEngine *fontEngine, QChar::Script script) override;
     QFontEngine *fontEngine(const QFontDef &fontDef, void *handle) override;
     QFontEngine *fontEngine(const QByteArray &fontData, qreal pixelSize, QFont::HintingPreference hintingPreference) override;

src/gui/text/windows/qwindowsdirectwritefontdatabase.cpp

@@ -249,12 +249,15 @@ QStringList QWindowsDirectWriteFontDatabase::addApplicationFont(const QByteArray
         loadedData = file.readAll();
     }
 
-    IDWriteFontFace *face = createDirectWriteFace(loadedData);
-    if (face == nullptr) {
+    QList<IDWriteFontFace *> faces = createDirectWriteFaces(loadedData);
+    if (faces.isEmpty()) {
         qCWarning(lcQpaFonts) << "Failed to create DirectWrite face from font data. Font may be unsupported.";
         return QStringList();
     }
 
+    QStringList ret;
+    for (int i = 0; i < faces.size(); ++i) {
+        IDWriteFontFace *face = faces.at(i);
         wchar_t defaultLocale[LOCALE_NAME_MAX_LENGTH];
         bool hasDefaultLocale = GetUserDefaultLocaleName(defaultLocale, LOCALE_NAME_MAX_LENGTH) != 0;
         wchar_t englishLocale[] = L"en-us";
@@ -269,7 +272,6 @@ QStringList QWindowsDirectWriteFontDatabase::addApplicationFont(const QByteArray
         writingSystems.setSupported(QFontDatabase::Any);
         writingSystems.setSupported(QFontDatabase::Latin);
 
-    QStringList ret;
         IDWriteFontFace3 *face3 = nullptr;
         if (SUCCEEDED(face->QueryInterface(__uuidof(IDWriteFontFace3),
                                           reinterpret_cast<void **>(&face3)))) {
@@ -341,6 +343,7 @@ QStringList QWindowsDirectWriteFontDatabase::addApplicationFont(const QByteArray
         }
 
         face->Release();
+    }
 
     return ret;
 }
@@ -425,4 +428,17 @@ QFont QWindowsDirectWriteFontDatabase::defaultFont() const
     return QFont(QStringLiteral("Segoe UI"));
 }
 
+bool QWindowsDirectWriteFontDatabase::supportsVariableApplicationFonts() const
+{
+    QSharedPointer<QWindowsFontEngineData> fontEngineData = data();
+    IDWriteFactory5 *factory5 = nullptr;
+    if (SUCCEEDED(fontEngineData->directWriteFactory->QueryInterface(__uuidof(IDWriteFactory5),
+                                                                     reinterpret_cast<void **>(&factory5)))) {
+        factory5->Release();
+        return true;
+    }
+
+    return false;
+}
+
 QT_END_NAMESPACE

src/gui/text/windows/qwindowsdirectwritefontdatabase_p.h

@@ -47,6 +47,7 @@ public:
 
     bool fontsAlwaysScalable() const override;
     bool isPrivateFontFamily(const QString &family) const override;
+    bool supportsVariableApplicationFonts() const override;
 
 private:
     friend class QWindowsFontEngineDirectWrite;

src/gui/text/windows/qwindowsfontdatabasebase.cpp

@@ -550,8 +550,12 @@ void QWindowsFontDatabaseBase::createDirectWriteFactory(IDWriteFactory **factory
     IUnknown *result = nullptr;
 
 #  if QT_CONFIG(directwrite3)
+    DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory5), &result);
+
+    if (result == nullptr)
         DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory3), &result);
 #  endif
+
     if (result == nullptr)
         DWriteCreateFactory(DWRITE_FACTORY_TYPE_SHARED, __uuidof(IDWriteFactory2), &result);
 
@@ -692,12 +696,22 @@ QFont QWindowsFontDatabaseBase::systemDefaultFont()
 }
 
 #if QT_CONFIG(directwrite) && QT_CONFIG(direct2d)
-IDWriteFontFace *QWindowsFontDatabaseBase::createDirectWriteFace(const QByteArray &fontData) const
+IDWriteFontFace *QWindowsFontDatabaseBase::createDirectWriteFace(const QByteArray &fontData)
 {
+    QList<IDWriteFontFace *> faces = createDirectWriteFaces(fontData, false);
+    Q_ASSERT(faces.size() <= 1);
+
+    return faces.isEmpty() ? nullptr : faces.first();
+}
+
+QList<IDWriteFontFace *> QWindowsFontDatabaseBase::createDirectWriteFaces(const QByteArray &fontData,
+                                                                          bool queryVariations) const
+{
+    QList<IDWriteFontFace *> ret;
     QSharedPointer<QWindowsFontEngineData> fontEngineData = data();
     if (fontEngineData->directWriteFactory == nullptr) {
         qCWarning(lcQpaFonts) << "DirectWrite factory not created in QWindowsFontDatabaseBase::createDirectWriteFace()";
-        return nullptr;
+        return ret;
     }
 
     CustomFontFileLoader fontFileLoader(fontEngineData->directWriteFactory);
@@ -712,7 +726,7 @@ IDWriteFontFace *QWindowsFontDatabaseBase::createDirectWriteFace(const QByteArra
                                                                                      &fontFile);
     if (FAILED(hres)) {
         qErrnoWarning(hres, "%s: CreateCustomFontFileReference failed", __FUNCTION__);
-        return nullptr;
+        return ret;
     }
 
     BOOL isSupportedFontType;
@@ -722,10 +736,46 @@ IDWriteFontFace *QWindowsFontDatabaseBase::createDirectWriteFace(const QByteArra
     fontFile->Analyze(&isSupportedFontType, &fontFileType, &fontFaceType, &numberOfFaces);
     if (!isSupportedFontType) {
         fontFile->Release();
-        return nullptr;
+        return ret;
     }
 
+#if QT_CONFIG(directwrite3)
+    IDWriteFactory5 *factory5 = nullptr;
+    if (queryVariations && SUCCEEDED(fontEngineData->directWriteFactory->QueryInterface(__uuidof(IDWriteFactory5),
+                                                                                        reinterpret_cast<void **>(&factory5)))) {
+
+        IDWriteFontSetBuilder1 *builder;
+        if (SUCCEEDED(factory5->CreateFontSetBuilder(&builder))) {
+            if (SUCCEEDED(builder->AddFontFile(fontFile))) {
+                IDWriteFontSet *fontSet;
+                if (SUCCEEDED(builder->CreateFontSet(&fontSet))) {
+                    int count = fontSet->GetFontCount();
+                    qCDebug(lcQpaFonts) << "Found" << count << "variations in font file";
+                    for (int i = 0; i < count; ++i) {
+                        IDWriteFontFaceReference *ref;
+                        if (SUCCEEDED(fontSet->GetFontFaceReference(i, &ref))) {
+                            IDWriteFontFace3 *face;
+                            if (SUCCEEDED(ref->CreateFontFace(&face))) {
+                                ret.append(face);
+                            }
+                            ref->Release();
+                        }
+                    }
+                    fontSet->Release();
+                }
+            }
+
+            builder->Release();
+        }
+
+        factory5->Release();
+    }
+#else
+    Q_UNUSED(queryVariations);
+#endif
+
     // ### Currently no support for .ttc, but we could easily return a list here.
+    if (ret.isEmpty()) {
         IDWriteFontFace *directWriteFontFace = nullptr;
         hres = fontEngineData->directWriteFactory->CreateFontFace(fontFaceType,
                                                                   1,
@@ -736,11 +786,14 @@ IDWriteFontFace *QWindowsFontDatabaseBase::createDirectWriteFace(const QByteArra
         if (FAILED(hres)) {
             qErrnoWarning(hres, "%s: CreateFontFace failed", __FUNCTION__);
             fontFile->Release();
-        return nullptr;
+            return ret;
+        } else {
+            ret.append(directWriteFontFace);
+        }
     }
 
     fontFile->Release();
-    return directWriteFontFace;
+    return ret;
 }
 #endif // directwrite && direct2d
 
@@ -760,7 +813,10 @@ QFontEngine *QWindowsFontDatabaseBase::fontEngine(const QByteArray &fontData, qr
     if (fontEngineData->directWriteFactory == nullptr)
         return nullptr;
 
-    IDWriteFontFace *directWriteFontFace = createDirectWriteFace(fontData);
+    IDWriteFontFace * directWriteFontFace = createDirectWriteFace(fontData);
+    if (directWriteFontFace == nullptr)
+        return nullptr;
+
     fontEngine = new QWindowsFontEngineDirectWrite(directWriteFontFace,
                                                    pixelSize,
                                                    fontEngineData);

src/gui/text/windows/qwindowsfontdatabasebase_p.h

@@ -91,7 +91,9 @@ public:
 protected:
 
 #if QT_CONFIG(directwrite)
-    IDWriteFontFace *createDirectWriteFace(const QByteArray &fontData) const;
+    QList<IDWriteFontFace *> createDirectWriteFaces(const QByteArray &fontData,
+                                                    bool queryVariations = true) const;
+    IDWriteFontFace *createDirectWriteFace(const QByteArray &fontData);
 #endif
 
 private:

tests/auto/gui/text/qfontdatabase/tst_qfontdatabase.cpp

@@ -12,6 +12,9 @@
 #include <private/qfont_p.h>
 #include <private/qfontengine_p.h>
 #include <qpa/qplatformfontdatabase.h>
+#include <qpa/qplatformintegration.h>
+
+#include <QtGui/private/qguiapplication_p.h>
 
 using namespace Qt::StringLiterals;
 
@@ -513,11 +516,9 @@ void tst_QFontDatabase::findCourier()
 void tst_QFontDatabase::variableFont()
 {
     {
-        QFont f;
-        f.setStyleStrategy(QFont::NoFontMerging);
-        QFontPrivate *font_d = QFontPrivate::get(f);
-        if (!font_d->engineForScript(QChar::Script_Common)->supportsVariableApplicationFonts())
-            QSKIP("Variable application fonts only supported on Freetype currently");
+        QPlatformFontDatabase *pfdb = QGuiApplicationPrivate::platformIntegration()->fontDatabase();
+        if (!pfdb->supportsVariableApplicationFonts())
+            QSKIP("Variable application fonts not supported on this platform");
     }
 
     int id = QFontDatabase::addApplicationFont(m_testFontVariable);