Integrating QProxyStyle

This class adds convenient support for proxy styles in Qt.
Note that to support proper proxying, styles now
call their functions through proxy() so that the proxy regains control
over subcomponents. Note that there is a small price to be payed
by the extra function call which can at the cost of readability
be redirected to the private class member in the future.

Task-number: 229556
Reviewed-by: trond

3 files changed, 87 insertions, 74 deletions

diff --git a/src/gui/kernel/qapplication.cpp b/src/gui/kernel/qapplication.cpp
index 4ab653d..b066f4d 100644
--- a/src/gui/kernel/qapplication.cpp
+++ b/src/gui/kernel/qapplication.cpp
@@ -391,6 +391,7 @@ Qt::MouseButtons QApplicationPrivate::mouse_buttons = Qt::NoButton;
 Qt::KeyboardModifiers QApplicationPrivate::modifier_buttons = Qt::NoModifier;
 
 QStyle *QApplicationPrivate::app_style = 0;        // default application style
+QString QApplicationPrivate::styleOverride;        // style override
 
 #ifndef QT_NO_STYLE_STYLESHEET
 QString QApplicationPrivate::styleSheet;           // default application stylesheet
@@ -438,7 +439,6 @@ bool QApplicationPrivate::animate_tooltip = false;
 bool QApplicationPrivate::fade_tooltip = false;
 bool QApplicationPrivate::animate_toolbox = false;
 bool QApplicationPrivate::widgetCount = false;
-QString* QApplicationPrivate::styleOverride = 0;
 #if defined(Q_WS_WIN) && !defined(Q_WS_WINCE)
 bool QApplicationPrivate::inSizeMove = false;
 #endif
@@ -548,9 +548,7 @@ void QApplicationPrivate::process_cmdline()
                 delete app_style;
                 app_style = 0;
             }
-            if (!styleOverride)
-                styleOverride = new QString;
-            *styleOverride = s;
+            styleOverride = s;
         }
     }
 
@@ -1287,44 +1285,14 @@ QStyle *QApplication::style()
         return 0;
     }
 
-#if defined(Q_WS_X11)
-    if(!QApplicationPrivate::styleOverride)
-        QApplicationPrivate::x11_initialize_style(); // run-time search for default style
-#endif
     if (!QApplicationPrivate::app_style) {
         // Compile-time search for default style
         //
         QString style;
-        if (QApplicationPrivate::styleOverride) {
-            style = *QApplicationPrivate::styleOverride;
-            delete QApplicationPrivate::styleOverride;
-            QApplicationPrivate::styleOverride = 0;
-        } else {
-#if defined(Q_WS_WIN) && defined(Q_WS_WINCE)
-    if (qt_wince_is_smartphone() || qt_wince_is_pocket_pc())
-        style = QLatin1String("WindowsMobile");
-     else
-        style = QLatin1String("WindowsCE");
-
-#elif defined(Q_WS_WIN)
-            if ((QSysInfo::WindowsVersion >= QSysInfo::WV_VISTA
-                && QSysInfo::WindowsVersion < QSysInfo::WV_NT_based))
-                style = QLatin1String("WindowsVista");
-                else if ((QSysInfo::WindowsVersion >= QSysInfo::WV_XP
-                && QSysInfo::WindowsVersion < QSysInfo::WV_NT_based))
-                style = QLatin1String("WindowsXP");
-            else
-                style = QLatin1String("Windows");                // default styles for Windows
-#elif defined(Q_WS_X11) && defined(Q_OS_SOLARIS)
-            style = QLatin1String("CDE");                        // default style for X11 on Solaris
-#elif defined(Q_WS_X11) && defined(Q_OS_IRIX)
-            style = QLatin1String("SGI");                        // default style for X11 on IRIX
-#elif defined(Q_WS_X11) || defined(Q_WS_QWS)
-            style = QLatin1String("Plastique");                  // default style for X11 and small devices
-#elif defined(Q_WS_MAC)
-                style = QLatin1String("Macintosh");              // default style for all Mac's
-#endif
-        }
+        if (!QApplicationPrivate::styleOverride.isEmpty())
+            style = QApplicationPrivate::styleOverride;
+        else
+            style = QApplicationPrivate::desktopStyleKey();
 
         QStyle *&app_style = QApplicationPrivate::app_style;
         app_style = QStyleFactory::create(style);
@@ -1412,9 +1380,8 @@ void QApplication::setStyle(QStyle *style)
     } else
 #endif // QT_NO_STYLE_STYLESHEET
         QApplicationPrivate::app_style = style;
-
     QApplicationPrivate::app_style->setParent(qApp); // take ownership
-
+    
     // take care of possible palette requirements of certain gui
     // styles. Do it before polishing the application since the style
     // might call QApplication::setPalette() itself
@@ -1936,6 +1903,40 @@ void QApplicationPrivate::setSystemFont(const QFont &font)
         QApplication::setFont(*sys_font);
 }
 
+/*! \internal
+*/
+QString QApplicationPrivate::desktopStyleKey()
+{
+QString desktopstyle;
+#if defined(Q_WS_WIN) && defined(Q_WS_WINCE)
+    if (qt_wince_is_smartphone() || qt_wince_is_pocket_pc())
+        desktopstyle = QLatin1String("WindowsMobile");
+     else
+        desktopstyle = QLatin1String("WindowsCE");
+
+#elif defined(Q_WS_WIN)
+            if ((QSysInfo::WindowsVersion >= QSysInfo::WV_VISTA
+                && QSysInfo::WindowsVersion < QSysInfo::WV_NT_based))
+                desktopstyle = QLatin1String("WindowsVista");
+                else if ((QSysInfo::WindowsVersion >= QSysInfo::WV_XP
+                && QSysInfo::WindowsVersion < QSysInfo::WV_NT_based))
+                desktopstyle = QLatin1String("WindowsXP");
+            else
+                desktopstyle = QLatin1String("Windows");                // default styles for Windows
+#elif defined(Q_WS_X11) && defined(Q_OS_SOLARIS)
+            desktopstyle = QLatin1String("CDE");                        // default style for X11 on Solaris
+#elif defined(Q_WS_X11) && defined(Q_OS_IRIX)
+            desktopstyle = QLatin1String("SGI");                        // default style for X11 on IRIX
+#elif defined(Q_WS_QWS)
+            desktopstyle = QLatin1String("Plastique");                  // default style for X11 and small devices
+#elif defined(Q_WS_X11)
+            desktopstyle = QApplicationPrivate::x11_desktop_style();     // default runtime dependant style for X11
+#elif defined(Q_WS_MAC)
+                desktopstyle = QLatin1String("Macintosh");              // default style for all Mac's
+#endif
+    return desktopstyle;
+}
+
 /*!
     \property QApplication::windowIcon
     \brief the default window icon
diff --git a/src/gui/kernel/qapplication_p.h b/src/gui/kernel/qapplication_p.h
index 7e97418..dd2f479 100644
--- a/src/gui/kernel/qapplication_p.h
+++ b/src/gui/kernel/qapplication_p.h
@@ -210,6 +210,7 @@ public:
 #if defined(Q_WS_X11)
 #ifndef QT_NO_SETTINGS
     static QString kdeHome();
+    static QString x11_desktop_style();
     static bool x11_apply_settings();
 #endif
     static void reset_instance_pointer();
@@ -223,6 +224,7 @@ public:
     static int autoMaximizeThreshold;
     static bool autoSipEnabled;
 #endif
+    static QString desktopStyleKey();
 
     static QGraphicsSystem *graphicsSystem()
 #if !defined(Q_WS_QWS)
@@ -392,7 +394,7 @@ public:
 
     static QApplicationPrivate *instance() { return self; }
 
-    static QString *styleOverride;
+    static QString styleOverride;
 
     static int app_compile_version;
 
diff --git a/src/gui/kernel/qapplication_x11.cpp b/src/gui/kernel/qapplication_x11.cpp
index 720f5c3..a94347b 100644
--- a/src/gui/kernel/qapplication_x11.cpp
+++ b/src/gui/kernel/qapplication_x11.cpp
@@ -799,6 +799,14 @@ Q_GUI_EXPORT void qt_x11_apply_settings_in_all_apps()
                     PropModeReplace, (unsigned char *)stamp.data(), stamp.size());
 }
 
+static int kdeSessionVersion()
+{
+    static int kdeVersion = 0;
+    if (!kdeVersion)
+        kdeVersion = QString::fromLocal8Bit(qgetenv("KDE_SESSION_VERSION")).toInt();
+    return kdeVersion;
+}
+
 /*! \internal
     Gets the current KDE 3 or 4 home path
 */
@@ -808,10 +816,9 @@ QString QApplicationPrivate::kdeHome()
     if (kdeHomePath.isEmpty()) {
         kdeHomePath = QString::fromLocal8Bit(qgetenv("KDEHOME"));
         if (kdeHomePath.isEmpty()) {
-            int kdeSessionVersion = QString::fromLocal8Bit(qgetenv("KDE_SESSION_VERSION")).toInt();
             QDir homeDir(QDir::homePath());
             QString kdeConfDir(QLatin1String("/.kde"));
-            if (4 == kdeSessionVersion && homeDir.exists(QLatin1String(".kde4")))
+            if (4 == kdeSessionVersion() && homeDir.exists(QLatin1String(".kde4")))
                 kdeConfDir = QLatin1String("/.kde4");
             kdeHomePath = QDir::homePath() + kdeConfDir;
         }
@@ -880,13 +887,11 @@ bool QApplicationPrivate::x11_apply_settings()
             QApplicationPrivate::setSystemPalette(pal);
     }
 
-    int kdeSessionVersion = QString::fromLocal8Bit(qgetenv("KDE_SESSION_VERSION")).toInt();
-
     if (!appFont) {
         QFont font(QApplication::font());
         QString fontDescription;
         // Override Qt font if KDE4 settings can be used
-        if (4 == kdeSessionVersion) {
+        if (4 == kdeSessionVersion()) {
             QSettings kdeSettings(kdeHome() + QLatin1String("/share/config/kdeglobals"), QSettings::IniFormat);
             fontDescription = kdeSettings.value(QLatin1String("font")).toString();
             if (fontDescription.isEmpty()) {
@@ -916,29 +921,16 @@ bool QApplicationPrivate::x11_apply_settings()
 
     // read new QStyle
     QString stylename = settings.value(QLatin1String("style")).toString();
-    if (stylename.isEmpty() && !QApplicationPrivate::styleOverride && X11->use_xrender) {
-        QStringList availableStyles = QStyleFactory::keys();
-        // Override Qt style if KDE4 settings can be used
-        if (4 == kdeSessionVersion) {
-            QSettings kdeSettings(kdeHome() + QLatin1String("/share/config/kdeglobals"), QSettings::IniFormat);
-            QString kde4Style = kdeSettings.value(QLatin1String("widgetStyle"),
-                                                  QLatin1String("Oxygen")).toString();
-            foreach (const QString &style, availableStyles) {
-                if (style.toLower() == kde4Style.toLower())
-                    stylename = kde4Style;
-            }
-        // Set QGtkStyle for GNOME
-        } else if (X11->desktopEnvironment == DE_GNOME) {
-            QString gtkStyleKey = QString::fromLatin1("GTK+");
-            if (availableStyles.contains(gtkStyleKey))
-                stylename = gtkStyleKey;
-        }
+
+
+    if (stylename.isEmpty() && QApplicationPrivate::styleOverride.isNull() && X11->use_xrender) {
+        stylename = x11_desktop_style();
     }
 
     static QString currentStyleName = stylename;
     if (QCoreApplication::startingUp()) {
-        if (!stylename.isEmpty() && !QApplicationPrivate::styleOverride)
-            QApplicationPrivate::styleOverride = new QString(stylename);
+        if (!stylename.isEmpty() && QApplicationPrivate::styleOverride.isNull())
+            QApplicationPrivate::styleOverride = stylename;
     } else {
         if (currentStyleName != stylename) {
             currentStyleName = stylename;
@@ -2625,31 +2617,49 @@ void qt_init(QApplicationPrivate *priv, int,
 /*!
     \internal
 */
-void QApplicationPrivate::x11_initialize_style()
+QString QApplicationPrivate::x11_desktop_style()
 {
-    if (QApplicationPrivate::app_style)
-        return;
+    QString stylename;
+    QStringList availableStyles = QStyleFactory::keys();
+    // Override Qt style if KDE4 settings can be used
+    if (4 == kdeSessionVersion()) {
+        QSettings kdeSettings(kdeHome() + QLatin1String("/share/config/kdeglobals"), QSettings::IniFormat);
+        QString kde4Style = kdeSettings.value(QLatin1String("widgetStyle"),
+                                              QLatin1String("Oxygen")).toString();
+        foreach (const QString &style, availableStyles) {
+            if (style.toLower() == kde4Style.toLower())
+                stylename = kde4Style;
+        }
+    // Set QGtkStyle for GNOME
+    } else if (X11->desktopEnvironment == DE_GNOME) {
+        QString gtkStyleKey = QString::fromLatin1("GTK+");
+        if (availableStyles.contains(gtkStyleKey))
+            stylename = gtkStyleKey;
+    }
 
-    switch(X11->desktopEnvironment) {
+    if (stylename.isEmpty()) {
+        switch(X11->desktopEnvironment) {
         case DE_KDE:
             if (X11->use_xrender)
-                QApplicationPrivate::app_style = QStyleFactory::create(QLatin1String("plastique"));
+                stylename = QLatin1String("plastique");
             else
-                QApplicationPrivate::app_style = QStyleFactory::create(QLatin1String("windows"));
+                stylename = QLatin1String("windows");
             break;
         case DE_GNOME:
             if (X11->use_xrender)
-                QApplicationPrivate::app_style = QStyleFactory::create(QLatin1String("cleanlooks"));
+                stylename = QLatin1String("cleanlooks");
             else
-                QApplicationPrivate::app_style = QStyleFactory::create(QLatin1String("windows"));
+                stylename = QLatin1String("windows");
             break;
         case DE_CDE:
-            QApplicationPrivate::app_style = QStyleFactory::create(QLatin1String("cde"));
+            stylename = QLatin1String("cde");
             break;
         default:
             // Don't do anything
             break;
+        }
     }
+    return stylename;
 }
 
 void QApplicationPrivate::initializeWidgetPaletteHash()