Window attached property: fix notifier signals

The change notifiers must be emitted when an item's window is
reset. Otherwise any existing bindings don't get re-evaluated,
and in worst scenario one ends up with dangling pointers.

Change-Id: I6075957f1447bb8628d25bd822345e45837c027a
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

2 files changed, 13 insertions, 8 deletions

diff --git a/src/quick/items/qquickwindowattached.cpp b/src/quick/items/qquickwindowattached.cpp
index e33e32631c..b1961386bb 100644
--- a/src/quick/items/qquickwindowattached.cpp
+++ b/src/quick/items/qquickwindowattached.cpp
@@ -89,21 +89,21 @@ void QQuickWindowAttached::windowChanged(QQuickWindow *window)
         if (oldWindow)
             oldWindow->disconnect(this);
 
-        if (!window)
-            return; // No values to get, therefore nothing to emit
-
-        if (!oldWindow || window->visibility() != oldWindow->visibility())
+        if (!oldWindow || !window || window->visibility() != oldWindow->visibility())
             emit visibilityChanged();
-        if (!oldWindow || window->isActive() != oldWindow->isActive())
+        if (!oldWindow || !window || window->isActive() != oldWindow->isActive())
             emit activeChanged();
-        if (!oldWindow || window->activeFocusItem() != oldWindow->activeFocusItem())
+        if (!oldWindow || !window || window->activeFocusItem() != oldWindow->activeFocusItem())
             emit activeFocusItemChanged();
         emit contentItemChanged();
-        if (!oldWindow || window->width() != oldWindow->width())
+        if (!oldWindow || !window || window->width() != oldWindow->width())
             emit widthChanged();
-        if (!oldWindow || window->height() != oldWindow->height())
+        if (!oldWindow || !window || window->height() != oldWindow->height())
             emit heightChanged();
 
+        if (!window)
+            return;
+
         // QQuickWindowQmlImpl::visibilityChanged also exists, and window might even
         // be QQuickWindowQmlImpl, but that's not what we are connecting to.
         // So this is actual window state rather than a buffered or as-requested one.
diff --git a/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp b/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
index f53ade9541..c597cf03dd 100644
--- a/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
+++ b/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
@@ -2050,6 +2050,11 @@ void tst_qquickwindow::attachedProperty()
     QCOMPARE(text->property("contentItem").value<QQuickItem*>(), innerWindow->contentItem());
     QCOMPARE(text->property("windowWidth").toInt(), innerWindow->width());
     QCOMPARE(text->property("windowHeight").toInt(), innerWindow->height());
+
+    text->setParentItem(0);
+    QVERIFY(!text->property("contentItem").value<QQuickItem*>());
+    QCOMPARE(text->property("windowWidth").toInt(), 0);
+    QCOMPARE(text->property("windowHeight").toInt(), 0);
 }
 
 class RenderJob : public QRunnable