Symbian control invokes slots before and after native draw ops

Direct Screen Access (DSA) allows a client to request notification
from the window server when drawing is performed by other threads,
into a specified region of the screen.  This allows DSA rendering
- for example video - to be suspended when notifications are
drawn, preventing the video content from overwriting the
notification.

If the drawing originates from the same thread as that which holds
the DSA session, DSA must be suspended while drawing takes place.
This change allows a widget to request notification when native
drawing is about to be performed by QSymbianControl::Draw.

Task-number: QTBUG-5467
Reviewed-by: Jason Barron

3 files changed, 29 insertions, 0 deletions

diff --git a/src/gui/kernel/qapplication_s60.cpp b/src/gui/kernel/qapplication_s60.cpp
index ae7b494..d1471eb 100644
--- a/src/gui/kernel/qapplication_s60.cpp
+++ b/src/gui/kernel/qapplication_s60.cpp
@@ -812,6 +812,12 @@ void QSymbianControl::Draw(const TRect& controlRect) const
     if (!engine)
         return;
 
+    const bool sendNativePaintEvents = qwidget->d_func()->extraData()->receiveNativePaintEvents;
+    if (sendNativePaintEvents) {
+        const QRect r = qt_TRect2QRect(controlRect);
+        QMetaObject::invokeMethod(qwidget, "beginNativePaintEvent", Qt::DirectConnection, Q_ARG(QRect, r));
+    }
+
     // Map source rectangle into coordinates of the backing store.
     const QPoint controlBase(controlRect.iTl.iX, controlRect.iTl.iY);
     const QPoint backingStoreBase = qwidget->mapTo(qwidget->window(), controlBase);
@@ -851,6 +857,19 @@ void QSymbianControl::Draw(const TRect& controlRect) const
     } else {
         surface->flush(qwidget, QRegion(qt_TRect2QRect(backingStoreRect)), QPoint());
     }
+
+    if (sendNativePaintEvents) {
+        const QRect r = qt_TRect2QRect(controlRect);
+        // The draw ops aren't actually sent to WSERV until the graphics
+        // context is deactivated, which happens in the function calling
+        // this one.  We therefore delay the delivery of endNativePaintEvent,
+        // to ensure that drawing has completed by the time the widget
+        // receives the event.  Note that, if the widget needs to ensure
+        // that the draw ops have actually been executed into the output
+        // framebuffer, a call to RWsSession::Flush is required in the
+        // endNativePaintEvent implementation.
+        QMetaObject::invokeMethod(qwidget, "endNativePaintEvent", Qt::QueuedConnection, Q_ARG(QRect, r));
+    }
 }
 
 void QSymbianControl::SizeChanged()
diff --git a/src/gui/kernel/qwidget_p.h b/src/gui/kernel/qwidget_p.h
index 025d703..04cf4bb 100644
--- a/src/gui/kernel/qwidget_p.h
+++ b/src/gui/kernel/qwidget_p.h
@@ -257,6 +257,15 @@ struct QWExtra {
 
     NativePaintMode nativePaintMode : 2;
 
+    /**
+     * If this bit is set, each native widget receives the signals from the
+     * Symbian control immediately before and immediately after draw ops are
+     * sent to the window server for this control:
+     *      void beginNativePaintEvent(const QRect &paintRect);
+     *      void endNativePaintEvent(const QRect &paintRect);
+     */
+    uint receiveNativePaintEvents : 1;
+
 #endif
 };
 
diff --git a/src/gui/kernel/qwidget_s60.cpp b/src/gui/kernel/qwidget_s60.cpp
index d7d76df..37614c7 100644
--- a/src/gui/kernel/qwidget_s60.cpp
+++ b/src/gui/kernel/qwidget_s60.cpp
@@ -882,6 +882,7 @@ void QWidgetPrivate::createSysExtra()
 {
     extra->activated = 0;
     extra->nativePaintMode = QWExtra::Default;
+    extra->receiveNativePaintEvents = 0;
 }
 
 void QWidgetPrivate::deleteSysExtra()