Introduce FontSmoothingGamma as a platform style hint.

- Allocate gamma tables on the heap in a thread-safe way, use
  font smoothing returned by the style hints of the platform to
  calculate them.
- Improve font rendering on Windows.

Change-Id: I8cd39b51cf03cbd642474c02b9076814baecd597
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

6 files changed, 29 insertions, 1 deletions

diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 5a95ebe848..4cd02c3d5b 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -61,6 +61,7 @@
 #include <qpalette.h>
 #include <qscreen.h>
 #include <private/qscreen_p.h>
+#include <private/qdrawhelper_p.h>
 
 #include <QtGui/QPlatformIntegration>
 #include <QtGui/QGenericPluginFactory>
@@ -764,6 +765,7 @@ QGuiApplicationPrivate::~QGuiApplicationPrivate()
     delete  platform_theme;
     delete platform_integration;
     platform_integration = 0;
+    delete m_gammaTables.load();
 }
 
 #if 0
@@ -2170,4 +2172,17 @@ void QGuiApplicationPrivate::notifyThemeChanged()
     }
 }
 
+const QDrawHelperGammaTables *QGuiApplicationPrivate::gammaTables()
+{
+    QDrawHelperGammaTables *result = m_gammaTables.load();
+    if (!result){
+        const qreal smoothing = qApp->styleHints()->fontSmoothingGamma();
+        QDrawHelperGammaTables *tables = new QDrawHelperGammaTables(smoothing);
+        if (!m_gammaTables.testAndSetRelease(0, tables))
+            delete tables;
+        result = m_gammaTables.load();
+    }
+    return result;
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qguiapplication_p.h b/src/gui/kernel/qguiapplication_p.h
index f30a2bb5a0..4d8ef6fadd 100644
--- a/src/gui/kernel/qguiapplication_p.h
+++ b/src/gui/kernel/qguiapplication_p.h
@@ -61,6 +61,7 @@ QT_BEGIN_NAMESPACE
 
 class QPlatformIntegration;
 class QPlatformTheme;
+struct QDrawHelperGammaTables;
 
 class Q_GUI_EXPORT QGuiApplicationPrivate : public QCoreApplicationPrivate
 {
@@ -203,6 +204,8 @@ public:
     };
     QHash<QWindow *, SynthesizedMouseData> synthesizedMousePoints;
 
+    const QDrawHelperGammaTables *gammaTables();
+
 protected:
     virtual void notifyThemeChanged();
 
@@ -212,6 +215,7 @@ private:
     static QGuiApplicationPrivate *self;
     static QTouchDevice *m_fakeTouchDevice;
     static int m_fakeMouseSourcePointId;
+    QAtomicPointer<QDrawHelperGammaTables> m_gammaTables;
 };
 
 Q_GUI_EXPORT uint qHash(const QGuiApplicationPrivate::ActiveTouchPointsKey &k);
diff --git a/src/gui/kernel/qplatformintegration_qpa.cpp b/src/gui/kernel/qplatformintegration_qpa.cpp
index 6879f0517e..4efd2d896f 100644
--- a/src/gui/kernel/qplatformintegration_qpa.cpp
+++ b/src/gui/kernel/qplatformintegration_qpa.cpp
@@ -293,6 +293,8 @@ QVariant QPlatformIntegration::styleHint(StyleHint hint) const
         return false;
     case PasswordMaskDelay:
         return 0;
+    case FontSmoothingGamma:
+        return qreal(1.7);
     }
 
     return 0;
diff --git a/src/gui/kernel/qplatformintegration_qpa.h b/src/gui/kernel/qplatformintegration_qpa.h
index 68dfc21833..fe40fd3dad 100644
--- a/src/gui/kernel/qplatformintegration_qpa.h
+++ b/src/gui/kernel/qplatformintegration_qpa.h
@@ -122,7 +122,8 @@ public:
         StartDragTime,
         KeyboardAutoRepeatRate,
         ShowIsFullScreen,
-        PasswordMaskDelay
+        PasswordMaskDelay,
+        FontSmoothingGamma
     };
 
     virtual QVariant styleHint(StyleHint hint) const;
diff --git a/src/gui/kernel/qstylehints.cpp b/src/gui/kernel/qstylehints.cpp
index 4970f6a26b..9384d34097 100644
--- a/src/gui/kernel/qstylehints.cpp
+++ b/src/gui/kernel/qstylehints.cpp
@@ -101,4 +101,9 @@ int QStyleHints::passwordMaskDelay() const
     return hint(QPlatformIntegration::PasswordMaskDelay).toInt();
 }
 
+qreal QStyleHints::fontSmoothingGamma() const
+{
+    return hint(QPlatformIntegration::FontSmoothingGamma).toReal();
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qstylehints.h b/src/gui/kernel/qstylehints.h
index ae51ebc052..301b51868f 100644
--- a/src/gui/kernel/qstylehints.h
+++ b/src/gui/kernel/qstylehints.h
@@ -63,6 +63,7 @@ public:
     int cursorFlashTime() const;
     bool showIsFullScreen() const;
     int passwordMaskDelay() const;
+    qreal fontSmoothingGamma() const;
 
 private:
     friend class QGuiApplication;