QQuickAnimatorJob: store the target with a QPointer

This avoids ending up with invalid pointers when under some circumstances the
target (which is not owned by the QQuickAnimatorJob) is destroyed between the
time the QQuickAnimatorJob is created and the time it is initialized. This is
the case when the target of an Animator is the item loaded by a Loader and
that the animator is started just before setting the Loader to inactive.

Also added an auto test for that special case.

Task-number: QTBUG-49634
Change-Id: Iab9bfe76d13755ba735432c6f97bde175d308814
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

2 files changed, 6 insertions, 1 deletions

diff --git a/src/quick/util/qquickanimatorcontroller.cpp b/src/quick/util/qquickanimatorcontroller.cpp
index cfb6037d14..74930fb373 100644
--- a/src/quick/util/qquickanimatorcontroller.cpp
+++ b/src/quick/util/qquickanimatorcontroller.cpp
@@ -140,6 +140,11 @@ static void qquick_initialize_helper(QAbstractAnimationJob *job, QQuickAnimatorC
 {
     if (job->isRenderThreadJob()) {
         QQuickAnimatorJob *j = static_cast<QQuickAnimatorJob *>(job);
+        // Note: since a QQuickAnimatorJob::m_target is a QPointer,
+        // if m_target is destroyed between the time it was set
+        // as the target of the animator job and before this step,
+        // (e.g a Loader being set inactive just after starting the animator)
+        // we are sure it will be NULL and won't be dangling around
         if (!j->target()) {
             return;
         } else if (c->m_deletedSinceLastFrame.contains(j->target())) {
diff --git a/src/quick/util/qquickanimatorjob_p.h b/src/quick/util/qquickanimatorjob_p.h
index 82c9da1d2e..35057d6278 100644
--- a/src/quick/util/qquickanimatorjob_p.h
+++ b/src/quick/util/qquickanimatorjob_p.h
@@ -152,7 +152,7 @@ protected:
     QQuickAnimatorJob();
     void debugAnimation(QDebug d) const Q_DECL_OVERRIDE;
 
-    QQuickItem *m_target;
+    QPointer<QQuickItem> m_target;
     QQuickAnimatorController *m_controller;
 
     qreal m_from;