Window change notification QQuickWidget

QQuickWidget and QOpenGLWidget needs to know when the window changes so
it can use the correct GL context.

Task-number: QTBUG-37045
Change-Id: Ib98b18e721908017398518f73226cb3731886927
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

src/corelib/kernel/qcoreevent.cpp

@@ -274,6 +274,7 @@ QT_BEGIN_NAMESPACE
     \omitvalue NetworkReplyUpdated
     \omitvalue FutureCallOut
     \omitvalue NativeGesture
+    \omitvalue WindowChangeInternal
 */
 
 /*!

src/corelib/kernel/qcoreevent.h

@@ -278,6 +278,8 @@ public:
         StyleAnimationUpdate = 213,             // style animation target should be updated
         ApplicationStateChange = 214,
 
+        WindowChangeInternal = 215,             // internal for QQuickWidget
+
         // 512 reserved for Qt Jambi's MetaCall event
         // 513 reserved for Qt Jambi's DeleteOnMainThread event
 

src/widgets/kernel/qwidget.cpp

@@ -9596,6 +9596,23 @@ void QWidget::setParent(QWidget *parent)
     setParent((QWidget*)parent, windowFlags() & ~Qt::WindowType_Mask);
 }
 
+#ifndef QT_NO_OPENGL
+static void sendWindowChangeToTextureChildrenRecursively(QWidget *widget)
+{
+    QWidgetPrivate *d = QWidgetPrivate::get(widget);
+    if (d->renderToTexture) {
+        QEvent e(QEvent::WindowChangeInternal);
+        QApplication::sendEvent(widget, &e);
+    }
+
+    for (int i = 0; i < d->children.size(); ++i) {
+        QWidget *w = qobject_cast<QWidget *>(d->children.at(i));
+        if (w && !w->isWindow() && !w->isHidden() && QWidgetPrivate::get(w)->textureChildSeen)
+            sendWindowChangeToTextureChildrenRecursively(w);
+    }
+}
+#endif
+
 /*!
     \overload
 
@@ -9720,6 +9737,12 @@ void QWidget::setParent(QWidget *parent, Qt::WindowFlags f)
         QEvent e(QEvent::ParentChange);
         QApplication::sendEvent(this, &e);
     }
+#ifndef QT_NO_OPENGL
+    //renderToTexture widgets also need to know when their top-level window changes
+    if (d->textureChildSeen && oldtlw != window()) {
+        sendWindowChangeToTextureChildrenRecursively(this);
+    }
+#endif
 
     if (!wasCreated) {
         if (isWindow() || parentWidget()->isVisible())