Make deletion of transitions safe

Task-number: QTBUG-63844
Change-Id: I65029e9039ea3db85152fc3cdefaac3deee0db6c
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

3 files changed, 39 insertions, 23 deletions

diff --git a/src/quick/items/qquickitemviewtransition_p.h b/src/quick/items/qquickitemviewtransition_p.h
index 3d2f5361b1..29a62f7f10 100644
--- a/src/quick/items/qquickitemviewtransition_p.h
+++ b/src/quick/items/qquickitemviewtransition_p.h
@@ -58,6 +58,8 @@ QT_REQUIRE_CONFIG(quick_viewtransitions);
 #include <QtCore/qobject.h>
 #include <QtCore/qpoint.h>
 #include <QtQml/qqml.h>
+#include <private/qqmlguard_p.h>
+#include <private/qquicktransition_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -115,14 +117,14 @@ public:
     QList<QObject *> moveTransitionTargets;
     QList<QObject *> removeTransitionTargets;
 
-    QQuickTransition *populateTransition;
-    QQuickTransition *addTransition;
-    QQuickTransition *addDisplacedTransition;
-    QQuickTransition *moveTransition;
-    QQuickTransition *moveDisplacedTransition;
-    QQuickTransition *removeTransition;
-    QQuickTransition *removeDisplacedTransition;
-    QQuickTransition *displacedTransition;
+    QQmlGuard<QQuickTransition> populateTransition;
+    QQmlGuard<QQuickTransition> addTransition;
+    QQmlGuard<QQuickTransition> addDisplacedTransition;
+    QQmlGuard<QQuickTransition> moveTransition;
+    QQmlGuard<QQuickTransition> moveDisplacedTransition;
+    QQmlGuard<QQuickTransition> removeTransition;
+    QQmlGuard<QQuickTransition> removeDisplacedTransition;
+    QQmlGuard<QQuickTransition> displacedTransition;
 
 private:
     friend class QQuickItemViewTransitionJob;
diff --git a/src/quick/util/qquicktransition.cpp b/src/quick/util/qquicktransition.cpp
index 29690a4857..6ae89c4ed4 100644
--- a/src/quick/util/qquicktransition.cpp
+++ b/src/quick/util/qquicktransition.cpp
@@ -109,7 +109,7 @@ protected:
     void updateState(QAbstractAnimationJob::State newState, QAbstractAnimationJob::State oldState) override;
 };
 
-class QQuickTransitionPrivate : public QObjectPrivate, QAnimationJobChangeListener
+class QQuickTransitionPrivate : public QObjectPrivate
 {
     Q_DECLARE_PUBLIC(QQuickTransition)
 public:
@@ -120,11 +120,8 @@ public:
     {
     }
 
-    void removeStateChangeListener(QAbstractAnimationJob *anim)
-    {
-        if (anim)
-            anim->removeAnimationChangeListener(this, QAbstractAnimationJob::StateChange);
-    }
+    static QQuickTransitionPrivate *get(QQuickTransition *q) { return q->d_func(); }
+    void animationStateChanged(QAbstractAnimationJob::State newState);
 
     QString fromState;
     QString toState;
@@ -134,7 +131,6 @@ public:
     bool reversible;
     bool enabled;
 protected:
-    void animationStateChanged(QAbstractAnimationJob *, QAbstractAnimationJob::State, QAbstractAnimationJob::State) override;
 
     static void append_animation(QQmlListProperty<QQuickAbstractAnimation> *list, QQuickAbstractAnimation *a);
     static int animation_count(QQmlListProperty<QQuickAbstractAnimation> *list);
@@ -171,7 +167,16 @@ void QQuickTransitionPrivate::clear_animations(QQmlListProperty<QQuickAbstractAn
     }
 }
 
-void QQuickTransitionPrivate::animationStateChanged(QAbstractAnimationJob *, QAbstractAnimationJob::State newState, QAbstractAnimationJob::State)
+void QQuickTransitionInstance::animationStateChanged(QAbstractAnimationJob *, QAbstractAnimationJob::State newState, QAbstractAnimationJob::State)
+{
+    if (!m_transition)
+        return;
+
+    QQuickTransitionPrivate *transition = QQuickTransitionPrivate::get(m_transition);
+    transition->animationStateChanged(newState);
+}
+
+void QQuickTransitionPrivate::animationStateChanged(QAbstractAnimationJob::State newState)
 {
     Q_Q(QQuickTransition);
 
@@ -197,15 +202,16 @@ void ParallelAnimationWrapper::updateState(QAbstractAnimationJob::State newState
     }
 }
 
-QQuickTransitionInstance::QQuickTransitionInstance(QQuickTransitionPrivate *transition, QAbstractAnimationJob *anim)
+QQuickTransitionInstance::QQuickTransitionInstance(QQuickTransition *transition, QAbstractAnimationJob *anim)
     : m_transition(transition)
     , m_anim(anim)
 {
+    anim->addAnimationChangeListener(this, QAbstractAnimationJob::StateChange);
 }
 
 QQuickTransitionInstance::~QQuickTransitionInstance()
 {
-    m_transition->removeStateChangeListener(m_anim);
+    removeStateChangeListener();
     delete m_anim;
 }
 
@@ -270,8 +276,7 @@ QQuickTransitionInstance *QQuickTransition::prepare(QQuickStateOperation::Action
 
     group->setDirection(d->reversed ? QAbstractAnimationJob::Backward : QAbstractAnimationJob::Forward);
 
-    group->addAnimationChangeListener(d, QAbstractAnimationJob::StateChange);
-    QQuickTransitionInstance *wrapper = new QQuickTransitionInstance(d, group);
+    QQuickTransitionInstance *wrapper = new QQuickTransitionInstance(this, group);
     return wrapper;
 }
 
diff --git a/src/quick/util/qquicktransition_p.h b/src/quick/util/qquicktransition_p.h
index d6f365f99e..6d2e41fc9d 100644
--- a/src/quick/util/qquicktransition_p.h
+++ b/src/quick/util/qquicktransition_p.h
@@ -53,6 +53,7 @@
 
 #include "qquickstate_p.h"
 #include <private/qabstractanimationjob_p.h>
+#include <private/qqmlguard_p.h>
 #include <qqml.h>
 
 #include <QtCore/qobject.h>
@@ -64,10 +65,10 @@ class QQuickTransitionPrivate;
 class QQuickTransitionManager;
 class QQuickTransition;
 
-class QQuickTransitionInstance
+class QQuickTransitionInstance : QAnimationJobChangeListener
 {
 public:
-    QQuickTransitionInstance(QQuickTransitionPrivate *transition, QAbstractAnimationJob *anim);
+    QQuickTransitionInstance(QQuickTransition *transition, QAbstractAnimationJob *anim);
     ~QQuickTransitionInstance();
 
     void start();
@@ -75,8 +76,16 @@ public:
 
     bool isRunning() const;
 
+protected:
+    void animationStateChanged(QAbstractAnimationJob *, QAbstractAnimationJob::State, QAbstractAnimationJob::State) override;
+
+    void removeStateChangeListener()
+    {
+        m_anim->removeAnimationChangeListener(this, QAbstractAnimationJob::StateChange);
+    }
+
 private:
-    QQuickTransitionPrivate *m_transition;
+    QQmlGuard<QQuickTransition> m_transition;
     QAbstractAnimationJob *m_anim;
     friend class QQuickTransition;
 };