Add QPlatformWindow::windowEvent()

This function is used to pass non-spontaneous events from QWindow to
QPlatformWindow so that QPlatformWindow subclasses can do any platform
specific event handling (such as setting/clearing modality flags on
QEvent::WindowBlock/WindowUnblock).

Change-Id: I82a89e8dadcd2f706aae25889d79cbfac9c2ee18
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@nokia.com>

src/gui/kernel/qguiapplication.cpp

@@ -1032,6 +1032,7 @@ bool QGuiApplication::notify(QObject *object, QEvent *event)
     }
 #endif
 
+    QGuiApplicationPrivate::sendQWindowEventToQPlatformWindow(qobject_cast<QWindow *>(object), event);
     return QCoreApplication::notify(object, event);
 }
 
@@ -1053,6 +1054,20 @@ bool QGuiApplication::compressEvent(QEvent *event, QObject *receiver, QPostEvent
     return QCoreApplication::compressEvent(event, receiver, postedEvents);
 }
 
+void QGuiApplicationPrivate::sendQWindowEventToQPlatformWindow(QWindow *window, QEvent *event)
+{
+    if (!window)
+        return;
+    QPlatformWindow *platformWindow = window->handle();
+    if (!platformWindow)
+        return;
+    // spontaneous events come from the platform integration already, we don't need to send the events back
+    if (event->spontaneous())
+        return;
+    // let the platform window do any handling it needs to as well
+    platformWindow->windowEvent(event);
+}
+
 bool QGuiApplicationPrivate::processNativeEvent(QWindow *window, const QByteArray &eventType, void *message, long *result)
 {
     return window->nativeEvent(eventType, message, result);

src/gui/kernel/qguiapplication_p.h

@@ -129,6 +129,8 @@ public:
 
     static bool processNativeEvent(QWindow *window, const QByteArray &eventType, void *message, long *result);
 
+    static void sendQWindowEventToQPlatformWindow(QWindow *window, QEvent *event);
+
     static inline Qt::Alignment visualAlignment(Qt::LayoutDirection direction, Qt::Alignment alignment)
     {
         if (!(alignment & Qt::AlignHorizontal_Mask))

src/gui/kernel/qplatformwindow_qpa.cpp

@@ -310,6 +310,18 @@ bool QPlatformWindow::setMouseGrabEnabled(bool grab)
     return false;
 }
 
+/*!
+    Reimplement this method to be able to do any platform specific event
+    handling. All events for window() are passed to this function before being
+    sent to QWindow::event().
+
+    The default implementation is empty and does nothing with \a event.
+*/
+void QPlatformWindow::windowEvent(QEvent *event)
+{
+    Q_UNUSED(event);
+}
+
 /*!
     \class QPlatformWindow
     \since 4.8

src/gui/kernel/qplatformwindow_qpa.h

@@ -113,6 +113,8 @@ public:
     virtual bool setKeyboardGrabEnabled(bool grab);
     virtual bool setMouseGrabEnabled(bool grab);
 
+    virtual void windowEvent(QEvent *event);
+
 protected:
     QScopedPointer<QPlatformWindowPrivate> d_ptr;
 private:

src/widgets/kernel/qapplication.cpp

@@ -2992,6 +2992,8 @@ bool QApplication::notify(QObject *receiver, QEvent *e)
     d->checkReceiverThread(receiver);
 #endif
 
+    QGuiApplicationPrivate::sendQWindowEventToQPlatformWindow(qobject_cast<QWindow *>(receiver), e);
+
     // capture the current mouse/keyboard state
     if(e->spontaneous()) {
         if (e->type() == QEvent::MouseButtonPress