Thread safety for QFontEngineS60

On symbian, creating fonts requires a connection to the window server.
Window server sessions are not sharable across threads.
To avoid QFont crashing when used outside the GUI thread, we construct a
private session to the window server when the shared CONE session is not
available.
(CCoeEnv::Static() uses TLS, so it returns null outside of GUI thread)

The private session and screen device are stored in QThreadStorage, so
they are automatically deleted when the QThread exits.

Task-number: QTBUG-8874
Reviewed-by: mread

3 files changed, 57 insertions, 12 deletions

diff --git a/src/gui/kernel/qapplication_s60.cpp b/src/gui/kernel/qapplication_s60.cpp
index 78027b2..f39b462 100644
--- a/src/gui/kernel/qapplication_s60.cpp
+++ b/src/gui/kernel/qapplication_s60.cpp
@@ -2046,4 +2046,29 @@ void QApplication::restoreOverrideCursor()
 
 #endif // QT_NO_CURSOR
 
+QS60ThreadLocalData::QS60ThreadLocalData()
+{
+    CCoeEnv *env = CCoeEnv::Static();
+    if (env) {
+        //if this is the UI thread, share objects owned by CONE
+        usingCONEinstances = true;
+        wsSession = env->WsSession();
+        screenDevice = env->ScreenDevice();
+    }
+    else {
+        usingCONEinstances = false;
+        qt_symbian_throwIfError(wsSession.Connect(qt_s60GetRFs()));
+        screenDevice = new CWsScreenDevice(wsSession);
+        screenDevice->Construct();
+    }
+}
+
+QS60ThreadLocalData::~QS60ThreadLocalData()
+{
+    if (!usingCONEinstances) {
+        delete screenDevice;
+        wsSession.Close();
+    }
+}
+
 QT_END_NAMESPACE
diff --git a/src/gui/kernel/qt_s60_p.h b/src/gui/kernel/qt_s60_p.h
index 58da302..bec51b8 100644
--- a/src/gui/kernel/qt_s60_p.h
+++ b/src/gui/kernel/qt_s60_p.h
@@ -62,6 +62,7 @@
 #include "QtGui/qevent.h"
 #include "qpointer.h"
 #include "qapplication.h"
+#include "QtCore/qthreadstorage.h"
 #include <w32std.h>
 #include <coecntrl.h>
 #include <eikenv.h>
@@ -85,10 +86,21 @@ const TInt KInternalStatusPaneChange = 0x50000000;
 //this macro exists because EColor16MAP enum value doesn't exist in Symbian OS 9.2
 #define Q_SYMBIAN_ECOLOR16MAP TDisplayMode(13)
 
+class QS60ThreadLocalData
+{
+public:
+    QS60ThreadLocalData();
+    ~QS60ThreadLocalData();
+    bool usingCONEinstances;
+    RWsSession wsSession;
+    CWsScreenDevice *screenDevice;
+};
+
 class QS60Data
 {
 public:
     QS60Data();
+    QThreadStorage<QS60ThreadLocalData *> tls;
     TUid uid;
     int screenDepth;
     QPoint lastCursorPos;
@@ -125,9 +137,9 @@ public:
     int menuBeingConstructed : 1;
     QApplication::QS60MainApplicationFactory s60ApplicationFactory; // typedef'ed pointer type
     static inline void updateScreenSize();
-    static inline RWsSession& wsSession();
+    inline RWsSession& wsSession();
     static inline RWindowGroup& windowGroup();
-    static inline CWsScreenDevice* screenDevice();
+    inline CWsScreenDevice* screenDevice();
     static inline CCoeAppUi* appUi();
     static inline CEikMenuBar* menuBar();
 #ifdef Q_WS_S60
@@ -256,7 +268,10 @@ inline void QS60Data::updateScreenSize()
 
 inline RWsSession& QS60Data::wsSession()
 {
-    return CCoeEnv::Static()->WsSession();
+    if(!tls.hasLocalData()) {
+        tls.setLocalData(new QS60ThreadLocalData);
+    }
+    return tls.localData()->wsSession;
 }
 
 inline RWindowGroup& QS60Data::windowGroup()
@@ -266,7 +281,10 @@ inline RWindowGroup& QS60Data::windowGroup()
 
 inline CWsScreenDevice* QS60Data::screenDevice()
 {
-    return CCoeEnv::Static()->ScreenDevice();
+    if(!tls.hasLocalData()) {
+        tls.setLocalData(new QS60ThreadLocalData);
+    }
+    return tls.localData()->screenDevice;
 }
 
 inline CCoeAppUi* QS60Data::appUi()
diff --git a/src/gui/text/qfontdatabase_s60.cpp b/src/gui/text/qfontdatabase_s60.cpp
index 40fe3b7..61c5271 100644
--- a/src/gui/text/qfontdatabase_s60.cpp
+++ b/src/gui/text/qfontdatabase_s60.cpp
@@ -218,17 +218,19 @@ QFontEngineFTS60::QFontEngineFTS60(const QFontDef &fd)
 */
 qreal QFontEngineS60::pixelsToPoints(qreal pixels, Qt::Orientation orientation)
 {
+    CWsScreenDevice* device = S60->screenDevice();
     return (orientation == Qt::Horizontal?
-        S60->screenDevice()->HorizontalPixelsToTwips(pixels)
-        :S60->screenDevice()->VerticalPixelsToTwips(pixels)) / KTwipsPerPoint;
+        device->HorizontalPixelsToTwips(pixels)
+        :device->VerticalPixelsToTwips(pixels)) / KTwipsPerPoint;
 }
 
 qreal QFontEngineS60::pointsToPixels(qreal points, Qt::Orientation orientation)
 {
+    CWsScreenDevice* device = S60->screenDevice();
     const int twips = points * KTwipsPerPoint;
     return orientation == Qt::Horizontal?
-        S60->screenDevice()->HorizontalTwipsToPixels(twips)
-        :S60->screenDevice()->VerticalTwipsToPixels(twips);
+        device->HorizontalTwipsToPixels(twips)
+        :device->VerticalTwipsToPixels(twips);
 }
 
 QFontEngineMultiS60::QFontEngineMultiS60(QFontEngine *first, int script, const QStringList &fallbackFamilies)
@@ -267,16 +269,16 @@ static void initializeDb()
 
     QSymbianFbsHeapLock lock(QSymbianFbsHeapLock::Unlock);
     
-    const int numTypeFaces = QS60Data::screenDevice()->NumTypefaces();
+    const int numTypeFaces = S60->screenDevice()->NumTypefaces();
     const QSymbianFontDatabaseExtrasImplementation *dbExtras =
             static_cast<const QSymbianFontDatabaseExtrasImplementation*>(db->symbianExtras);
     bool fontAdded = false;
     for (int i = 0; i < numTypeFaces; i++) {
         TTypefaceSupport typefaceSupport;
-        QS60Data::screenDevice()->TypefaceSupport(typefaceSupport, i);
+        S60->screenDevice()->TypefaceSupport(typefaceSupport, i);
         CFont *font; // We have to get a font instance in order to know all the details
         TFontSpec fontSpec(typefaceSupport.iTypeface.iName, 11);
-        if (QS60Data::screenDevice()->GetNearestFontInPixels(font, fontSpec) != KErrNone)
+        if (S60->screenDevice()->GetNearestFontInPixels(font, fontSpec) != KErrNone)
             continue;
         if (font->TypeUid() == KCFbsFontUid) {
             TOpenFontFaceAttrib faceAttrib;
@@ -318,7 +320,7 @@ static void initializeDb()
 
             fontAdded = true;
         }
-        QS60Data::screenDevice()->ReleaseFont(font);
+        S60->screenDevice()->ReleaseFont(font);
     }
 
     Q_ASSERT(fontAdded);