Add new signals to indicate GPU resource usage.

QML elements that use GPU resources directly
needs to know when Qt releases GPU resources
and when they are available again.

Task-number: QT-5310
Reviewed-by: Samuel Rødal

Author: Jani Hautakangas

src/gui/kernel/qapplication.cpp

@@ -3389,7 +3389,35 @@ QString QApplication::sessionKey() const
 }
 #endif
 
+/*!
+    \since 4.7.4
+    \fn void QApplication::aboutToReleaseGpuResources()
+
+    This signal is emitted when application is about to release all
+    GPU resources accociated to contexts owned by application.
+
+    The signal is particularly useful if your application has allocated
+    GPU resources directly apart from Qt and needs to do some last-second
+    cleanup.
+
+    \warning This signal is only emitted on Symbian.
+
+    \sa aboutToUseGpuResources()
+*/
 
+/*!
+    \since 4.7.4
+    \fn void QApplication::aboutToUseGpuResources()
+
+    This signal is emitted when application is about to use GPU resources.
+
+    The signal is particularly useful if your application needs to know
+    when GPU resources are be available.
+
+   \warning This signal is only emitted on Symbian.
+
+   \sa aboutToFreeGpuResources()
+*/
 
 /*!
     \since 4.2

src/gui/kernel/qapplication.h

@@ -298,6 +298,10 @@ class Q_GUI_EXPORT QApplication : public QCoreApplication
     void commitDataRequest(QSessionManager &sessionManager);
     void saveStateRequest(QSessionManager &sessionManager);
 #endif
+#ifdef Q_OS_SYMBIAN
+    void aboutToReleaseGpuResources();
+    void aboutToUseGpuResources();
+#endif
 
 public:
     QString styleSheet() const;

src/gui/kernel/qapplication_p.h

@@ -523,6 +523,9 @@ class Q_GUI_EXPORT QApplicationPrivate : public QCoreApplicationPrivate
     int symbianResourceChange(const QSymbianEvent *symbianEvent);
 
     void _q_aboutToQuit();
+
+    void emitAboutToReleaseGpuResources();
+    void emitAboutToUseGpuResources();
 #endif
 #if defined(Q_WS_WIN) || defined(Q_WS_X11) || defined (Q_WS_QWS) || defined(Q_WS_MAC)
     void sendSyntheticEnterLeave(QWidget *widget);

src/gui/kernel/qapplication_s60.cpp

@@ -207,6 +207,9 @@ void QS60Data::controlVisibilityChanged(CCoeControl *control, bool visible)
         if (QTLWExtra *topData = qt_widget_private(window)->maybeTopData()) {
             QWidgetBackingStoreTracker &backingStore = topData->backingStore;
             if (visible) {
+                QApplicationPrivate *d = QApplicationPrivate::instance();
+                d->emitAboutToUseGpuResources();
+
                 if (backingStore.data()) {
                     backingStore.registerWidget(widget);
                 } else {
@@ -216,6 +219,9 @@ void QS60Data::controlVisibilityChanged(CCoeControl *control, bool visible)
                     widget->repaint();
                 }
             } else {
+                QApplicationPrivate *d = QApplicationPrivate::instance();
+                d->emitAboutToReleaseGpuResources();
+
                 // In certain special scenarios we may get an ENotVisible event
                 // without a previous EPartiallyVisible. The backingstore must
                 // still be destroyed, hence the registerWidget() call below.
@@ -2704,6 +2710,24 @@ void QApplicationPrivate::_q_aboutToQuit()
 #endif
 }
 
+void QApplicationPrivate::emitAboutToReleaseGpuResources()
+{
+#ifdef Q_SYMBIAN_SUPPORTS_SURFACES
+    Q_Q(QApplication);
+    QPointer<QApplication> guard(q);
+    emit q->aboutToReleaseGpuResources();
+#endif
+}
+
+void QApplicationPrivate::emitAboutToUseGpuResources()
+{
+#ifdef Q_SYMBIAN_SUPPORTS_SURFACES
+    Q_Q(QApplication);
+    QPointer<QApplication> guard(q);
+    emit q->aboutToUseGpuResources();
+#endif
+}
+
 QS60ThreadLocalData::QS60ThreadLocalData()
 {
     CCoeEnv *env = CCoeEnv::Static();

src/s60installs/eabi/QtGuiu.def

@@ -12198,4 +12198,11 @@ EXPORTS
 	_ZNK11QPixmapData15toVolatileImageEv @ 12197 NONAME
 	_ZNK14QVolatileImage13constImageRefEv @ 12198 NONAME
 	_Z43qt_s60_setPartialScreenAutomaticTranslationb @ 12199 NONAME
+	_ZN11QTextEngine16getClusterLengthEPtPK17HB_CharAttributesiiiPi @ 12200 NONAME
+	_ZN11QTextEngine18positionInLigatureEPK11QScriptItemi6QFixedS3_ib @ 12201 NONAME
+	_ZN12QApplication22aboutToUseGpuResourcesEv @ 12202 NONAME
+	_ZN12QApplication26aboutToReleaseGpuResourcesEv @ 12203 NONAME
+	_ZN14QWidgetPrivate16_q_cleanupWinIdsEv @ 12204 NONAME
+	_ZN19QApplicationPrivate26emitAboutToUseGpuResourcesEv @ 12205 NONAME
+	_ZN19QApplicationPrivate30emitAboutToReleaseGpuResourcesEv @ 12206 NONAME