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>

4 files changed, 85 insertions, 50 deletions

diff --git a/src/gui/painting/painting.pri b/src/gui/painting/painting.pri
index 3ce2e5b258..977aea26e3 100644
--- a/src/gui/painting/painting.pri
+++ b/src/gui/painting/painting.pri
@@ -75,6 +75,7 @@ SOURCES += \
         SOURCES +=                                      \
                 painting/qpaintengine_raster.cpp        \
                 painting/qdrawhelper.cpp                \
+                painting/qgammatables.cpp               \
                 painting/qimagescale.cpp                \
                 painting/qgrayraster.c                  \
                 painting/qpaintengine_blitter.cpp       \
diff --git a/src/gui/painting/qdrawhelper.cpp b/src/gui/painting/qdrawhelper.cpp
index 7571d81a36..774678c67f 100644
--- a/src/gui/painting/qdrawhelper.cpp
+++ b/src/gui/painting/qdrawhelper.cpp
@@ -39,6 +39,9 @@
 **
 ****************************************************************************/
 
+#include <qstylehints.h>
+#include <qguiapplication.h>
+#include <qatomic.h>
 #include <private/qdrawhelper_p.h>
 #include <private/qpaintengine_raster_p.h>
 #include <private/qpainter_p.h>
@@ -51,6 +54,7 @@
 #include <private/qdrawhelper_mips_dsp_p.h>
 #endif
 #include <private/qmath_p.h>
+#include <private/qguiapplication_p.h>
 #include <qmath.h>
 
 QT_BEGIN_NAMESPACE
@@ -5313,54 +5317,6 @@ inline static void qt_bitmapblit_quint16(QRasterBuffer *rasterBuffer,
                                     map, mapWidth, mapHeight, mapStride);
 }
 
-
-struct QDrawHelperGammaTables
-{
-    QDrawHelperGammaTables();
-
-    uchar qt_pow_rgb_gamma[256];
-    uchar qt_pow_rgb_invgamma[256];
-
-#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
-    uint qt_pow_gamma[256];
-    uchar qt_pow_invgamma[2048];
-#endif
-};
-
-QDrawHelperGammaTables::QDrawHelperGammaTables()
-{
-    qreal smoothing = qreal(1.7);
-
-    for (int i=0; i<256; ++i) {
-        qt_pow_rgb_gamma[i] = uchar(qRound(qPow(i / qreal(255.0), smoothing) * 255));
-        qt_pow_rgb_invgamma[i] = uchar(qRound(qPow(i / qreal(255.), 1 / smoothing) * 255));
-    }
-
-#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
-    const qreal gray_gamma = 2.31;
-    for (int i=0; i<256; ++i)
-        qt_pow_gamma[i] = uint(qRound(qPow(i / qreal(255.), gray_gamma) * 2047));
-    for (int i=0; i<2048; ++i)
-        qt_pow_invgamma[i] = uchar(qRound(qPow(i / qreal(2047.0), 1 / gray_gamma) * 255));
-#endif
-}
-
-Q_GLOBAL_STATIC(QDrawHelperGammaTables, qt_gamma_tables);
-
-#if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
-const uint *qt_pow_gamma()
-{
-    QDrawHelperGammaTables *tables = qt_gamma_tables();
-    return tables ? tables->qt_pow_gamma : 0;
-}
-#endif
-
-const uchar *qt_pow_rgb_gamma()
-{
-    QDrawHelperGammaTables *tables = qt_gamma_tables();
-    return tables ? tables->qt_pow_rgb_gamma : 0;
-}
-
 static void qt_alphamapblit_quint16(QRasterBuffer *rasterBuffer,
                                     int x, int y, quint32 color,
                                     const uchar *map,
@@ -5473,7 +5429,7 @@ static void qt_alphamapblit_quint32(QRasterBuffer *rasterBuffer,
     const int destStride = rasterBuffer->bytesPerLine() / sizeof(quint32);
 
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINCE)
-    QDrawHelperGammaTables *tables = qt_gamma_tables();
+    const QDrawHelperGammaTables *tables = QGuiApplicationPrivate::instance()->gammaTables();
     if (!tables)
         return;
 
@@ -5570,7 +5526,7 @@ static void qt_alphargbblit_quint32(QRasterBuffer *rasterBuffer,
     int sb = qBlue(color);
     int sa = qAlpha(color);
 
-    QDrawHelperGammaTables *tables = qt_gamma_tables();
+    const QDrawHelperGammaTables *tables = QGuiApplicationPrivate::instance()->gammaTables();
     if (!tables)
         return;
 
diff --git a/src/gui/painting/qdrawhelper_p.h b/src/gui/painting/qdrawhelper_p.h
index 442fd8bcd7..2e9f064951 100644
--- a/src/gui/painting/qdrawhelper_p.h
+++ b/src/gui/painting/qdrawhelper_p.h
@@ -328,6 +328,18 @@ struct QSpanData
     void adjustSpanMethods();
 };
 
+struct QDrawHelperGammaTables
+{
+    explicit QDrawHelperGammaTables(qreal smoothing);
+
+    void refresh(qreal smoothing);
+
+    uchar qt_pow_rgb_gamma[256];
+    uchar qt_pow_rgb_invgamma[256];
+    uint qt_pow_gamma[256];
+    uchar qt_pow_invgamma[2048];
+};
+
 static inline uint qt_gradient_clamp(const QGradientData *data, int ipos)
 {
     if (ipos < 0 || ipos >= GRADIENT_STOPTABLE_SIZE) {
diff --git a/src/gui/painting/qgammatables.cpp b/src/gui/painting/qgammatables.cpp
new file mode 100644
index 0000000000..06dc95a103
--- /dev/null
+++ b/src/gui/painting/qgammatables.cpp
@@ -0,0 +1,66 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <private/qdrawhelper_p.h>
+
+QT_BEGIN_NAMESPACE
+
+
+QDrawHelperGammaTables::QDrawHelperGammaTables(qreal smoothing)
+{
+    const qreal gray_gamma = 2.31;
+    for (int i=0; i<256; ++i)
+        qt_pow_gamma[i] = uint(qRound(qPow(i / qreal(255.), gray_gamma) * 2047));
+    for (int i=0; i<2048; ++i)
+        qt_pow_invgamma[i] = uchar(qRound(qPow(i / qreal(2047.0), 1 / gray_gamma) * 255));
+
+    refresh(smoothing);
+}
+
+void QDrawHelperGammaTables::refresh(qreal smoothing)
+{
+    for (int i=0; i<256; ++i) {
+        qt_pow_rgb_gamma[i] = uchar(qRound(qPow(i / qreal(255.0), smoothing) * 255));
+        qt_pow_rgb_invgamma[i] = uchar(qRound(qPow(i / qreal(255.), 1 / smoothing) * 255));
+    }
+}
+
+QT_END_NAMESPACE