5 files changed, 51 insertions, 0 deletions
diff --git a/src/gui/kernel/qplatformscreen.cpp b/src/gui/kernel/qplatformscreen.cpp
index 745b89018e..edf546799f 100644
--- a/src/gui/kernel/qplatformscreen.cpp
+++ b/src/gui/kernel/qplatformscreen.cpp
@@ -393,4 +393,31 @@ QRect QPlatformScreen::mapBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation
     return rect;
 }
 
+/*!
+  Returns a hint about this screen's subpixel layout structure.
+
+  The default implementation queries the \b{QT_SUBPIXEL_AA_TYPE} env variable.
+  This is just a hint because most platforms don't have a way to retrieve the correct value from hardware
+  and instead rely on font configurations.
+*/
+QPlatformScreen::SubpixelAntialiasingType QPlatformScreen::subpixelAntialiasingTypeHint() const
+{
+    static int type = -1;
+    if (type == -1) {
+        QByteArray env = qgetenv("QT_SUBPIXEL_AA_TYPE");
+        if (env == "RGB")
+            type = QPlatformScreen::Subpixel_RGB;
+        else if (env == "BGR")
+            type = QPlatformScreen::Subpixel_BGR;
+        else if (env == "VRGB")
+            type = QPlatformScreen::Subpixel_VRGB;
+        else if (env == "VBGR")
+            type = QPlatformScreen::Subpixel_VBGR;
+        else
+            type = QPlatformScreen::Subpixel_None;
+    }
+
+    return static_cast<QPlatformScreen::SubpixelAntialiasingType>(type);
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qplatformscreen.h b/src/gui/kernel/qplatformscreen.h
index fdae339815..551cb788c9 100644
--- a/src/gui/kernel/qplatformscreen.h
+++ b/src/gui/kernel/qplatformscreen.h
@@ -74,6 +74,14 @@ class Q_GUI_EXPORT QPlatformScreen
     Q_DECLARE_PRIVATE(QPlatformScreen)
 
 public:
+    enum SubpixelAntialiasingType { // copied from qfontengine_p.h since we can't include private headers
+        Subpixel_None,
+        Subpixel_RGB,
+        Subpixel_BGR,
+        Subpixel_VRGB,
+        Subpixel_VBGR
+    };
+
     QPlatformScreen();
     virtual ~QPlatformScreen();
 
@@ -107,6 +115,7 @@ public:
     virtual QString name() const { return QString(); }
 
     virtual QPlatformCursor *cursor() const;
+    virtual SubpixelAntialiasingType subpixelAntialiasingTypeHint() const;
 
     static int angleBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation b);
     static QTransform transformBetween(Qt::ScreenOrientation a, Qt::ScreenOrientation b, const QRect &target);
diff --git a/src/gui/text/qfontengine_ft_p.h b/src/gui/text/qfontengine_ft_p.h
index bcd2efaef8..8fd5ca23af 100644
--- a/src/gui/text/qfontengine_ft_p.h
+++ b/src/gui/text/qfontengine_ft_p.h
@@ -305,6 +305,7 @@ protected:
 private:
     friend class QFontEngineFTRawFont;
     friend class QFontconfigDatabase;
+    friend class QBasicFontDatabase;
     friend class QFontEngineMultiFontConfig;
 
     int loadFlags(QGlyphSet *set, GlyphFormat format, int flags, bool &hsubpixel, int &vfactor) const;
diff --git a/src/gui/text/qplatformfontdatabase.cpp b/src/gui/text/qplatformfontdatabase.cpp
index 080bfecefb..3c3000da4d 100644
--- a/src/gui/text/qplatformfontdatabase.cpp
+++ b/src/gui/text/qplatformfontdatabase.cpp
@@ -34,6 +34,9 @@
 #include "qplatformfontdatabase.h"
 #include <QtGui/private/qfontengine_p.h>
 #include <QtGui/private/qfontengine_qpf2_p.h>
+#include <QtGui/QGuiApplication>
+#include <QtGui/QScreen>
+#include <qpa/qplatformscreen.h>
 #include <QtCore/QLibraryInfo>
 #include <QtCore/QDir>
 
@@ -457,6 +460,15 @@ bool QPlatformFontDatabase::fontsAlwaysScalable() const
     return ret;
 }
 
+QFontEngine::SubpixelAntialiasingType QPlatformFontDatabase::subpixelAntialiasingTypeHint() const
+{
+    static int type = -1;
+    if (type == -1) {
+        if (QScreen *screen = QGuiApplication::primaryScreen())
+            type = screen->handle()->subpixelAntialiasingTypeHint();
+    }
+    return static_cast<QFontEngine::SubpixelAntialiasingType>(type);
+}
 
 // ### copied to tools/makeqpf/qpf2.cpp
 
diff --git a/src/gui/text/qplatformfontdatabase.h b/src/gui/text/qplatformfontdatabase.h
index 56934b066a..0615df65d6 100644
--- a/src/gui/text/qplatformfontdatabase.h
+++ b/src/gui/text/qplatformfontdatabase.h
@@ -49,6 +49,7 @@
 #include <QtCore/QList>
 #include <QtCore/QHash>
 #include <QtGui/QFontDatabase>
+#include <QtGui/private/qfontengine_p.h>
 #include <QtGui/private/qfont_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -107,6 +108,7 @@ public:
     virtual QString resolveFontFamilyAlias(const QString &family) const;
     virtual bool fontsAlwaysScalable() const;
     virtual QList<int> standardSizes() const;
+    QFontEngine::SubpixelAntialiasingType subpixelAntialiasingTypeHint() const;
 
     // helper
     static QSupportedWritingSystems writingSystemsFromTrueTypeBits(quint32 unicodeRange[4], quint32 codePageRange[2]);