Make Tumbler compatible with deferred execution

Now that the contentItem is created at a different stage, we
have to shuffle some code around and add some null checks.

Task-number: QTBUG-50992
Change-Id: I34d3a9ea9cb9ab54008a1015b37b1666538c085e
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

1 files changed, 29 insertions, 0 deletions

diff --git a/src/quicktemplates2/qquicktumbler_p_p.h b/src/quicktemplates2/qquicktumbler_p_p.h
index 0dcae762..38b0f60d 100644
--- a/src/quicktemplates2/qquicktumbler_p_p.h
+++ b/src/quicktemplates2/qquicktumbler_p_p.h
@@ -64,6 +64,7 @@ public:
     ~QQuickTumblerPrivate();
 
     enum ContentItemType {
+        NoContentItem,
         UnsupportedContentItemType,
         PathViewContentItem,
         ListViewContentItem
@@ -109,6 +110,34 @@ public:
     void itemChildRemoved(QQuickItem *, QQuickItem *) override;
 };
 
+class Q_QUICKTEMPLATES2_PRIVATE_EXPORT QQuickTumblerAttachedPrivate : public QObjectPrivate, public QQuickItemChangeListener
+{
+    Q_DECLARE_PUBLIC(QQuickTumblerAttached)
+
+public:
+    QQuickTumblerAttachedPrivate();
+
+    void init(QQuickItem *delegateItem);
+
+    void itemGeometryChanged(QQuickItem *item, QQuickGeometryChange change, const QRectF &diff) override;
+    void itemChildAdded(QQuickItem *, QQuickItem *) override;
+    void itemChildRemoved(QQuickItem *, QQuickItem *) override;
+
+    void _q_calculateDisplacement();
+    void emitIfDisplacementChanged(qreal oldDisplacement, qreal newDisplacement);
+
+    void viewDataSetUp();
+
+    static QQuickTumblerAttachedPrivate *get(QQuickTumblerAttached *attached);
+
+    // The Tumbler that contains the delegate. Required to calculated the displacement.
+    QPointer<QQuickTumbler> tumbler;
+    // The index of the delegate. Used to calculate the displacement.
+    int index;
+    // The displacement for our delegate.
+    qreal displacement;
+};
+
 QT_END_NAMESPACE
 
 #endif // QQUICKTUMBLER_P_P_H