Modified reparenting to correctly deal with native child widgets

Both reparenting and modification of window flags are done by calling
QWidget::setParent.  If either the parent changes, or a non-top-level
widget becomes top-level (as a result of OR-ing Qt::Window into its
window flags), a new native window ID is created for the widget.  The
Symbian implementation of setParent_sys had a flaw which manifested
itself in the following situation:

1. We start with a native widget X, and its child Y, which is also
native.  There exist parent-child relationships between the associated
CCoeControl instances, and the native windows (represented by RWindow
handles).
2. X gets a new native window created as a result of a call to
setParent.
3. QWidgetPrivate::reparentChildren calls SetParent on Y's control, to
re-establish the parent-child relationship.

The problem is that the window owned by Y's control now has no parent,
so if we try to re-size the widget, the window server panics the client
thread (WSERV-52).

Because Symbian does not allow existing windows to be re-parented, and
nor does it allow a window-owning control to re-create a new window,
the only way to provide Y's window with a parent is to destroy the
control and create a new one, passing in X's new window to the
CCoeControl::CreateWindowL function.

The changes made are as follows:

a) QWidgetPrivate::reparentChildren is therefore modified to call
create_sys, with destroyOldWindow set to true.
b) QWidgetPrivate::create_sys is modified to take account of the value
of this flag in all cases.  (Previously it only did so if a new WId was
passed in by the caller).
c) The call to setWinId is delayed until the control and window are
fully initialized.  This is to allow us to emit a new event,
WinIdChanged, from setWinId, in order to inform the widget that its
winId has changed.
d) QWidgetPrivate::activateSymbianWindow is modified in order to
support this change of call ordering.

Note that QWidgetPrivate::create_sys requires some re-factoring in
order to remove the redundancy between the top-level and child widget
cases.

Task-number: QTBUG-4664
Reviewed-by: axis

1 files changed, 47 insertions, 22 deletions

diff --git a/src/gui/kernel/qwidget_s60.cpp b/src/gui/kernel/qwidget_s60.cpp
index 3328cee..5527cc8 100644
--- a/src/gui/kernel/qwidget_s60.cpp
+++ b/src/gui/kernel/qwidget_s60.cpp
@@ -318,8 +318,6 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
     bool desktop = (type == Qt::Desktop);
     //bool tool = (type == Qt::Tool || type == Qt::Drawer);
 
-    WId id = 0;
-
     if (popup)
         flags |= Qt::WindowStaysOnTopHint; // a popup stays on top
 
@@ -341,13 +339,10 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
         data.crect.setSize(QSize(width, height));
     }
 
-    CCoeControl *destroyw = 0;
+    CCoeControl *const destroyw = destroyOldWindow ? data.winid : 0;
 
     createExtra();
     if (window) {
-        if (destroyOldWindow)
-            destroyw = data.winid;
-        id = window;
         setWinId(window);
         TRect tr = window->Rect();
         data.crect.setRect(tr.iTl.iX, tr.iTl.iY, tr.Width(), tr.Height());
@@ -355,10 +350,15 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
     } else if (topLevel) {
         if (!q->testAttribute(Qt::WA_Moved) && !q->testAttribute(Qt::WA_DontShowOnScreen))
             data.crect.moveTopLeft(QPoint(clientRect.iTl.iX, clientRect.iTl.iY));
-        QSymbianControl *control= q_check_ptr(new QSymbianControl(q));
-        id = (WId)control;
-        setWinId(id);
-        QT_TRAP_THROWING(control->ConstructL(true,desktop));
+
+        QScopedPointer<QSymbianControl> control( q_check_ptr(new QSymbianControl(q)) );
+        QT_TRAP_THROWING(control->ConstructL(true, desktop));
+
+        // Symbian windows are always created in an inactive state
+        // We perform this assignment for the case where the window is being re-created
+        // as aa result of a call to setParent_sys, on either this widget or one of its
+        // ancestors.
+        extra->activated = 0;
 
         if (!desktop) {
             TInt stackingFlags;
@@ -368,7 +368,7 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
                 stackingFlags = ECoeStackFlagStandard;
             }
             control->MakeVisible(false);
-            QT_TRAP_THROWING(control->ControlEnv()->AppUi()->AddToStackL(control, ECoeStackPriorityDefault, stackingFlags));
+            QT_TRAP_THROWING(control->ControlEnv()->AppUi()->AddToStackL(control.data(), ECoeStackPriorityDefault, stackingFlags));
             // Avoid keyboard focus to a hidden window.
             control->setFocusSafely(false);
 
@@ -391,11 +391,22 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
         int x, y, w, h;
         data.crect.getRect(&x, &y, &w, &h);
         control->SetRect(TRect(TPoint(x, y), TSize(w, h)));
+
+        // We wait until the control is fully constructed before calling setWinId, because
+        // this generates a WinIdChanged event.
+        setWinId(control.take());
+
     } else if (q->testAttribute(Qt::WA_NativeWindow) || paintOnScreen()) { // create native child widget
-        QSymbianControl *control = new QSymbianControl(q);
-        setWinId(control);
+
+        QScopedPointer<QSymbianControl> control( q_check_ptr(new QSymbianControl(q)) );
         QT_TRAP_THROWING(control->ConstructL(!parentWidget));
 
+        // Symbian windows are always created in an inactive state
+        // We perform this assignment for the case where the window is being re-created
+        // as aa result of a call to setParent_sys, on either this widget or one of its
+        // ancestors.
+        extra->activated = 0;
+
         TInt stackingFlags;
         if ((q->windowType() & Qt::Popup) == Qt::Popup) {
             stackingFlags = ECoeStackFlagRefusesAllKeys | ECoeStackFlagRefusesFocus;
@@ -403,7 +414,7 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
             stackingFlags = ECoeStackFlagStandard;
         }
         control->MakeVisible(false);
-        QT_TRAP_THROWING(control->ControlEnv()->AppUi()->AddToStackL(control, ECoeStackPriorityDefault, stackingFlags));
+        QT_TRAP_THROWING(control->ControlEnv()->AppUi()->AddToStackL(control.data(), ECoeStackPriorityDefault, stackingFlags));
         // Avoid keyboard focus to a hidden window.
         control->setFocusSafely(false);
 
@@ -418,7 +429,11 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
             | EPointerFilterMove | EPointerFilterDrag, 0);
 
         if (q->isVisible() && q->testAttribute(Qt::WA_Mapped))
-            activateSymbianWindow();
+            activateSymbianWindow(control.data());
+
+        // We wait until the control is fully constructed before calling setWinId, because
+        // this generates a WinIdChanged event.
+        setWinId(control.take());
     }
 
     if (destroyw) {
@@ -434,7 +449,7 @@ void QWidgetPrivate::create_sys(WId window, bool /* initializeWindow */, bool de
 void QWidgetPrivate::show_sys()
 {
     Q_Q(QWidget);
-    
+
     if (q->testAttribute(Qt::WA_OutsideWSRange))
         return;
 
@@ -468,7 +483,7 @@ void QWidgetPrivate::show_sys()
     invalidateBuffer(q->rect());
 }
 
-void QWidgetPrivate::activateSymbianWindow()
+void QWidgetPrivate::activateSymbianWindow(WId wid)
 {
     Q_Q(QWidget);
 
@@ -476,8 +491,12 @@ void QWidgetPrivate::activateSymbianWindow()
     Q_ASSERT(q->testAttribute(Qt::WA_Mapped));
     Q_ASSERT(!extra->activated);
 
-    WId id = q->internalWinId();
-    QT_TRAP_THROWING(id->ActivateL());
+    if(!wid)
+        wid = q->internalWinId();
+
+    Q_ASSERT(wid);
+
+    QT_TRAP_THROWING(wid->ActivateL());
     extra->activated = 1;
 }
 
@@ -566,8 +585,14 @@ void QWidgetPrivate::reparentChildren()
                 w->d_func()->invalidateBuffer(w->rect());
                 WId parent = q->effectiveWinId();
                 WId child = w->effectiveWinId();
-                if (parent != child)
-                    child->SetParent(parent);
+                if (parent != child) {
+                    // Child widget is native.  Because Symbian windows cannot be
+                    // re-parented, we must re-create the window.
+                    const WId window = 0;
+                    const bool initializeWindow = false;
+                    const bool destroyOldWindow = true;
+                    w->d_func()->create_sys(window, initializeWindow, destroyOldWindow);
+                }
                 // ### TODO: We probably also need to update the component array here
                 w->d_func()->reparentChildren();
             } else {
@@ -1253,7 +1278,7 @@ void QWidget::grabMouse()
         WId id = effectiveWinId();
         id->SetPointerCapture(true);
         QWidgetPrivate::mouseGrabber = this;
-        
+
 #ifndef QT_NO_CURSOR
         QApplication::setOverrideCursor(cursor());
 #endif