Allow canceling incubation

Qt Quick Controls must avoid destroying any object that belongs to
a tree of objects being incubated. The problem is that QQC have no
control over the incubation process. This patch adds private API
that allows QQC to cancel incubation of a specific item that QQC
would like to destroy.

Change-Id: Id9f9004736e2b53fe46cdb6bb3055b7457def94d
Task-number: QTBUG-50992
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 17 insertions, 0 deletions

diff --git a/src/qml/qml/qqmlincubator.cpp b/src/qml/qml/qqmlincubator.cpp
index 963638ca34..54d0b240f5 100644
--- a/src/qml/qml/qqmlincubator.cpp
+++ b/src/qml/qml/qqmlincubator.cpp
@@ -380,6 +380,23 @@ finishIncubate:
     }
 }
 
+void QQmlIncubatorPrivate::cancel(QObject *object, QQmlContext *context)
+{
+    if (!context)
+        context = qmlContext(object);
+    if (!context)
+        return;
+
+    QQmlContextData *data = QQmlContextData::get(context);
+    QQmlIncubatorPrivate *p = (QQmlIncubatorPrivate *)data->activeVMEData;
+    if (!p)
+        return;
+
+    p->vmeGuard.unguard(object);
+    if (!p->creator.isNull())
+        p->creator->cancel(object);
+}
+
 /*!
 Incubate objects for \a msecs, or until there are no more objects to incubate.
 */