Make it possible to enable non-scalable font scaling

Windows native font engine supports scaling of non-scalalble fonts, so
make it possible to do so.
Added two functions to QPlatformFontDatabase: fontsAlwaysScalable() and
standardSizes(), and made fontsAlwaysScalable() to return true for
Windows native font database.

Windows Freetype font engine doesn't seem to support scaling of
non-scalable fonts, so didn't enable it in there.

Added implementation of standardSizes() for Mac OS.

Task-number: QTBUG-24970
Change-Id: I41c9356ede8a37b7c61db94340dbeb5b629f34b9
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Bradley T. Hughes <bradley.hughes@nokia.com>
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>

4 files changed, 47 insertions, 12 deletions

diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index 468d029cf2..a1af856992 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -735,12 +735,13 @@ static void initFontDef(const QtFontDesc &desc, const QFontDef &request, QFontDe
         fontDef->family += QLatin1Char(']');
     }
 
-    if (desc.style->smoothScalable)
+    if (desc.style->smoothScalable
+        || QGuiApplicationPrivate::platformIntegration()->fontDatabase()->fontsAlwaysScalable()
+        || (desc.style->bitmapScalable && (request.styleStrategy & QFont::PreferMatch))) {
         fontDef->pixelSize = request.pixelSize;
-    else if ((desc.style->bitmapScalable && (request.styleStrategy & QFont::PreferMatch)))
-        fontDef->pixelSize = request.pixelSize;
-    else
+    } else {
         fontDef->pixelSize = desc.size->pixelSize;
+    }
 
     fontDef->styleHint     = request.styleHint;
     fontDef->styleStrategy = request.styleStrategy;
@@ -1534,6 +1535,9 @@ bool  QFontDatabase::isScalable(const QString &family,
 QList<int> QFontDatabase::pointSizes(const QString &family,
                                            const QString &styleName)
 {
+    if (QGuiApplicationPrivate::platformIntegration()->fontDatabase()->fontsAlwaysScalable())
+        return standardSizes();
+
     bool smoothScalable = false;
     QString familyName, foundryName;
     parseFontName(family, foundryName, familyName);
@@ -1634,6 +1638,9 @@ QFont QFontDatabase::font(const QString &family, const QString &style,
 QList<int> QFontDatabase::smoothSizes(const QString &family,
                                             const QString &styleName)
 {
+    if (QGuiApplicationPrivate::platformIntegration()->fontDatabase()->fontsAlwaysScalable())
+        return standardSizes();
+
     bool smoothScalable = false;
     QString familyName, foundryName;
     parseFontName(family, foundryName, familyName);
@@ -1689,12 +1696,7 @@ QList<int> QFontDatabase::smoothSizes(const QString &family,
 */
 QList<int> QFontDatabase::standardSizes()
 {
-    QList<int> ret;
-    static const unsigned short standard[] =
-        { 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 36, 48, 72, 0 };
-    const unsigned short *sizes = standard;
-    while (*sizes) ret << *sizes++;
-    return ret;
+    return QGuiApplicationPrivate::platformIntegration()->fontDatabase()->standardSizes();
 }
 
 
diff --git a/src/gui/text/qfontdatabase_qpa.cpp b/src/gui/text/qfontdatabase_qpa.cpp
index 0014efc450..c2a3aa9722 100644
--- a/src/gui/text/qfontdatabase_qpa.cpp
+++ b/src/gui/text/qfontdatabase_qpa.cpp
@@ -161,9 +161,12 @@ QFontEngine *loadSingleEngine(int script,
     Q_UNUSED(foundry);
 
     Q_ASSERT(size);
+    QPlatformFontDatabase *pfdb = QGuiApplicationPrivate::platformIntegration()->fontDatabase();
     int pixelSize = size->pixelSize;
-    if (!pixelSize || (style->smoothScalable && pixelSize == SMOOTH_SCALABLE))
+    if (!pixelSize || (style->smoothScalable && pixelSize == SMOOTH_SCALABLE)
+        || pfdb->fontsAlwaysScalable()) {
         pixelSize = request.pixelSize;
+    }
 
     QFontDef def = request;
     def.pixelSize = pixelSize;
@@ -171,7 +174,6 @@ QFontEngine *loadSingleEngine(int script,
     QFontCache::Key key(def,script);
     QFontEngine *engine = QFontCache::instance()->findEngine(key);
     if (!engine) {
-        QPlatformFontDatabase *pfdb = QGuiApplicationPrivate::platformIntegration()->fontDatabase();
         engine = pfdb->fontEngine(def,QUnicodeTables::Script(script),size->handle);
         if (engine) {
             QFontCache::Key key(def,script);
diff --git a/src/gui/text/qplatformfontdatabase_qpa.cpp b/src/gui/text/qplatformfontdatabase_qpa.cpp
index 6af0398f00..f6d82802f7 100644
--- a/src/gui/text/qplatformfontdatabase_qpa.cpp
+++ b/src/gui/text/qplatformfontdatabase_qpa.cpp
@@ -385,6 +385,35 @@ QString QPlatformFontDatabase::resolveFontFamilyAlias(const QString &family) con
 }
 
 /*!
+    Return true if all fonts are considered scalable when using this font database.
+    Defaults to false.
+
+    \since 5.0
+ */
+
+bool QPlatformFontDatabase::fontsAlwaysScalable() const
+{
+    return false;
+}
+
+/*!
+    Return list of standard font sizes when using this font database.
+
+    \since 5.0
+ */
+
+ QList<int> QPlatformFontDatabase::standardSizes() const
+{
+    QList<int> ret;
+    static const unsigned short standard[] =
+        { 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20, 22, 24, 26, 28, 36, 48, 72, 0 };
+    ret.reserve(int(sizeof(standard) / sizeof(standard[0])));
+    const unsigned short *sizes = standard;
+    while (*sizes) ret << *sizes++;
+    return ret;
+}
+
+/*!
     \class QPlatformFontDatabase
     \brief The QPlatformFontDatabase class makes it possible to customize how fonts
     are discovered and how they are rendered
diff --git a/src/gui/text/qplatformfontdatabase_qpa.h b/src/gui/text/qplatformfontdatabase_qpa.h
index 3810b75dbf..9fe3b0380d 100644
--- a/src/gui/text/qplatformfontdatabase_qpa.h
+++ b/src/gui/text/qplatformfontdatabase_qpa.h
@@ -102,6 +102,8 @@ public:
     virtual QFont defaultFont() const;
 
     virtual QString resolveFontFamilyAlias(const QString &family) const;
+    virtual bool fontsAlwaysScalable() const;
+    virtual QList<int> standardSizes() const;
 
     //callback
     static void registerQPF2Font(const QByteArray &dataArray, void *handle);