QQuickScrollBar & Indicator: cleanup item change listeners

It's a bit uncertain how it managed to slip through the CI, but tst_controls
is currently crashing consistently on Windows (MSVC 2015) during the cleanup
of ScrollBar::test_mirrored(). This patch fixes the crash, which happens due
to dangling listener pointers.

Change-Id: I0a3640786f01f98e9a2bcb600913a7d5fbfe4823
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 16 insertions, 6 deletions

diff --git a/src/quicktemplates2/qquickscrollindicator.cpp b/src/quicktemplates2/qquickscrollindicator.cpp
index bc53768c..55e86d87 100644
--- a/src/quicktemplates2/qquickscrollindicator.cpp
+++ b/src/quicktemplates2/qquickscrollindicator.cpp
@@ -243,6 +243,7 @@ public:
     void layoutVertical(bool move = true);
 
     void itemGeometryChanged(QQuickItem *item, const QRectF &newGeometry, const QRectF &oldGeometry) override;
+    void itemDestroyed(QQuickItem *item) override;
 
     QQuickFlickable *flickable;
     QQuickScrollIndicator *horizontal;
@@ -289,6 +290,14 @@ void QQuickScrollIndicatorAttachedPrivate::itemGeometryChanged(QQuickItem *item,
     }
 }
 
+void QQuickScrollIndicatorAttachedPrivate::itemDestroyed(QQuickItem *item)
+{
+    if (item == horizontal)
+        horizontal = nullptr;
+    if (item == vertical)
+        vertical = nullptr;
+}
+
 QQuickScrollIndicatorAttached::QQuickScrollIndicatorAttached(QQuickFlickable *flickable) :
     QObject(*(new QQuickScrollIndicatorAttachedPrivate(flickable)), flickable)
 {
@@ -304,9 +313,10 @@ QQuickScrollIndicatorAttached::~QQuickScrollIndicatorAttached()
     Q_D(QQuickScrollIndicatorAttached);
     if (d->flickable) {
         if (d->horizontal)
-            QQuickItemPrivate::get(d->horizontal)->removeItemChangeListener(d, QQuickItemPrivate::Geometry);
+            QQuickItemPrivate::get(d->horizontal)->removeItemChangeListener(d, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
         if (d->vertical)
-            QQuickItemPrivate::get(d->vertical)->removeItemChangeListener(d, QQuickItemPrivate::Geometry);
+            QQuickItemPrivate::get(d->vertical)->removeItemChangeListener(d,QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
+        QQuickItemPrivate::get(d->flickable)->removeItemChangeListener(d, QQuickItemPrivate::Geometry);
     }
 }
 
@@ -335,7 +345,7 @@ void QQuickScrollIndicatorAttached::setHorizontal(QQuickScrollIndicator *horizon
         return;
 
     if (d->horizontal && d->flickable) {
-        QQuickItemPrivate::get(d->horizontal)->removeItemChangeListener(d, QQuickItemPrivate::Geometry);
+        QQuickItemPrivate::get(d->horizontal)->removeItemChangeListener(d, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
         QObjectPrivate::disconnect(d->flickable, &QQuickFlickable::movingHorizontallyChanged, d, &QQuickScrollIndicatorAttachedPrivate::activateHorizontal);
 
         // TODO: export QQuickFlickableVisibleArea
@@ -351,7 +361,7 @@ void QQuickScrollIndicatorAttached::setHorizontal(QQuickScrollIndicator *horizon
             horizontal->setParentItem(d->flickable);
         horizontal->setOrientation(Qt::Horizontal);
 
-        QQuickItemPrivate::get(horizontal)->updateOrAddGeometryChangeListener(d, QQuickItemPrivate::SizeChange);
+        QQuickItemPrivate::get(horizontal)->addItemChangeListener(d, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
         QObjectPrivate::connect(d->flickable, &QQuickFlickable::movingHorizontallyChanged, d, &QQuickScrollIndicatorAttachedPrivate::activateHorizontal);
 
         // TODO: export QQuickFlickableVisibleArea
@@ -391,7 +401,7 @@ void QQuickScrollIndicatorAttached::setVertical(QQuickScrollIndicator *vertical)
         return;
 
     if (d->vertical && d->flickable) {
-        QQuickItemPrivate::get(d->vertical)->removeItemChangeListener(d, QQuickItemPrivate::Geometry);
+        QQuickItemPrivate::get(d->vertical)->removeItemChangeListener(d, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
         QObjectPrivate::disconnect(d->flickable, &QQuickFlickable::movingVerticallyChanged, d, &QQuickScrollIndicatorAttachedPrivate::activateVertical);
 
         // TODO: export QQuickFlickableVisibleArea
@@ -407,7 +417,7 @@ void QQuickScrollIndicatorAttached::setVertical(QQuickScrollIndicator *vertical)
             vertical->setParentItem(d->flickable);
         vertical->setOrientation(Qt::Vertical);
 
-        QQuickItemPrivate::get(vertical)->updateOrAddGeometryChangeListener(d, QQuickItemPrivate::SizeChange);
+        QQuickItemPrivate::get(vertical)->addItemChangeListener(d, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
         QObjectPrivate::connect(d->flickable, &QQuickFlickable::movingVerticallyChanged, d, &QQuickScrollIndicatorAttachedPrivate::activateVertical);
 
         // TODO: export QQuickFlickableVisibleArea