Reference count items in VisualItemModel.

The views expect the models to reference count and not destroy (or hide
in the case of VisualItemModel) until there are no references.

Task-number: QTBUG-12450
Reviewed-by: Michael Brasser
(cherry picked from commit d39d01497640c3a0818d25036894495f8b597bdb)

1 files changed, 37 insertions, 11 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativevisualitemmodel.cpp b/src/declarative/graphicsitems/qdeclarativevisualitemmodel.cpp
index 7952b97..79c1c43 100644
--- a/src/declarative/graphicsitems/qdeclarativevisualitemmodel.cpp
+++ b/src/declarative/graphicsitems/qdeclarativevisualitemmodel.cpp
@@ -78,7 +78,7 @@ public:
 
     static void children_append(QDeclarativeListProperty<QDeclarativeItem> *prop, QDeclarativeItem *item) {
         QDeclarative_setParent_noEvent(item, prop->object);
-        static_cast<QDeclarativeVisualItemModelPrivate *>(prop->data)->children.append(item);
+        static_cast<QDeclarativeVisualItemModelPrivate *>(prop->data)->children.append(Item(item));
         static_cast<QDeclarativeVisualItemModelPrivate *>(prop->data)->itemAppended();
         static_cast<QDeclarativeVisualItemModelPrivate *>(prop->data)->emitChildrenChanged();
     }
@@ -88,12 +88,12 @@ public:
     }
 
     static QDeclarativeItem *children_at(QDeclarativeListProperty<QDeclarativeItem> *prop, int index) {
-        return static_cast<QDeclarativeVisualItemModelPrivate *>(prop->data)->children.at(index);
+        return static_cast<QDeclarativeVisualItemModelPrivate *>(prop->data)->children.at(index).item;
     }
 
     void itemAppended() {
         Q_Q(QDeclarativeVisualItemModel);
-        QDeclarativeVisualItemModelAttached *attached = QDeclarativeVisualItemModelAttached::properties(children.last());
+        QDeclarativeVisualItemModelAttached *attached = QDeclarativeVisualItemModelAttached::properties(children.last().item);
         attached->setIndex(children.count()-1);
         emit q->itemsInserted(children.count()-1, 1);
         emit q->countChanged();
@@ -104,7 +104,25 @@ public:
         emit q->childrenChanged();
     }
 
-    QList<QDeclarativeItem *> children;
+    int indexOf(QDeclarativeItem *item) const {
+        for (int i = 0; i < children.count(); ++i)
+            if (children.at(i).item == item)
+                return i;
+        return -1;
+    }
+
+    class Item {
+    public:
+        Item(QDeclarativeItem *i) : item(i), ref(0) {}
+
+        void addRef() { ++ref; }
+        bool deref() { return --ref == 0; }
+
+        QDeclarativeItem *item;
+        int ref;
+    };
+
+    QList<Item> children;
 };
 
 
@@ -182,14 +200,22 @@ bool QDeclarativeVisualItemModel::isValid() const
 QDeclarativeItem *QDeclarativeVisualItemModel::item(int index, bool)
 {
     Q_D(QDeclarativeVisualItemModel);
-    return d->children.at(index);
+    QDeclarativeVisualItemModelPrivate::Item &item = d->children[index];
+    item.addRef();
+    return item.item;
 }
 
 QDeclarativeVisualModel::ReleaseFlags QDeclarativeVisualItemModel::release(QDeclarativeItem *item)
 {
-    if (item->scene())
-        item->scene()->removeItem(item);
-    QDeclarative_setParent_noEvent(item, this);
+    Q_D(QDeclarativeVisualItemModel);
+    int idx = d->indexOf(item);
+    if (idx >= 0) {
+        if (d->children[idx].deref()) {
+            if (item->scene())
+                item->scene()->removeItem(item);
+            QDeclarative_setParent_noEvent(item, this);
+        }
+    }
     return 0;
 }
 
@@ -208,7 +234,7 @@ QString QDeclarativeVisualItemModel::stringValue(int index, const QString &name)
     Q_D(QDeclarativeVisualItemModel);
     if (index < 0 || index >= d->children.count())
         return QString();
-    return QDeclarativeEngine::contextForObject(d->children.at(index))->contextProperty(name).toString();
+    return QDeclarativeEngine::contextForObject(d->children.at(index).item)->contextProperty(name).toString();
 }
 
 QVariant QDeclarativeVisualItemModel::evaluate(int index, const QString &expression, QObject *objectContext)
@@ -218,7 +244,7 @@ QVariant QDeclarativeVisualItemModel::evaluate(int index, const QString &express
         return QVariant();
     QDeclarativeContext *ccontext = qmlContext(this);
     QDeclarativeContext *ctxt = new QDeclarativeContext(ccontext);
-    ctxt->setContextObject(d->children.at(index));
+    ctxt->setContextObject(d->children.at(index).item);
     QDeclarativeExpression e(ctxt, objectContext, expression);
     QVariant value = e.evaluate();
     delete ctxt;
@@ -228,7 +254,7 @@ QVariant QDeclarativeVisualItemModel::evaluate(int index, const QString &express
 int QDeclarativeVisualItemModel::indexOf(QDeclarativeItem *item, QObject *) const
 {
     Q_D(const QDeclarativeVisualItemModel);
-    return d->children.indexOf(item);
+    return d->indexOf(item);
 }
 
 QDeclarativeVisualItemModelAttached *QDeclarativeVisualItemModel::qmlAttachedProperties(QObject *obj)