Curve renderer: Fix crash when root node is replaced

A curve renderer instance keeps references to the fill and stroke
nodes it has created, in order to facilitate maintaining correct
rendering order when updating. All nodes are children of the
renderer's root node.

It can happen, like when hiding and re-showing a Popup, that the
renderer instance is assigned a new root node. The references to the
child nodes are then invalid, and accessing them will fail.

Fix by clearing all such references when a new root node is set.

Fixes: QTBUG-128561
Change-Id: Ibc4992780867049e9e38a2bf1a163eed79bdc5c0
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
(cherry picked from commit cef3ff0a60d37615a5230a84ad172b357897fe7e)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit e20e91904a5131269196a1c7596fb05959fb5761)

2 files changed, 10 insertions, 0 deletions

diff --git a/src/quickshapes/qquickshapecurverenderer.cpp b/src/quickshapes/qquickshapecurverenderer.cpp
index acda4e4945..d45a120749 100644
--- a/src/quickshapes/qquickshapecurverenderer.cpp
+++ b/src/quickshapes/qquickshapecurverenderer.cpp
@@ -655,9 +655,18 @@ QQuickShapeCurveRenderer::NodeList QQuickShapeCurveRenderer::addTriangulatingStr
 
 void QQuickShapeCurveRenderer::setRootNode(QSGNode *node)
 {
+    clearNodeReferences();
     m_rootNode = node;
 }
 
+void QQuickShapeCurveRenderer::clearNodeReferences()
+{
+    for (PathData &pd : m_paths) {
+        pd.fillNodes.clear();
+        pd.strokeNodes.clear();
+    }
+}
+
 int QQuickShapeCurveRenderer::debugVisualizationFlags = QQuickShapeCurveRenderer::NoDebug;
 
 int QQuickShapeCurveRenderer::debugVisualization()
diff --git a/src/quickshapes/qquickshapecurverenderer_p.h b/src/quickshapes/qquickshapecurverenderer_p.h
index f2b10fb44c..2e8bed4814 100644
--- a/src/quickshapes/qquickshapecurverenderer_p.h
+++ b/src/quickshapes/qquickshapecurverenderer_p.h
@@ -62,6 +62,7 @@ public:
     void updateNode() override;
 
     void setRootNode(QSGNode *node);
+    void clearNodeReferences();
 
     using NodeList = QVector<QSGCurveAbstractNode *>;