Don't store the QSGNode pointer

The QSGNode subtree may be cleared at any time. Get the subtree via the
node pointer passed in updatePaintNode, to ensure that the subtree is
still valid each update.

Some references are still being stored but invalidated when a new
subtree is created. QTBUG-34994 has been created to track fixing that.

Task-number: QTBUG-33553
Change-Id: I2115aff931d42b613d207553c636be7d80c405bb
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

1 files changed, 21 insertions, 21 deletions

diff --git a/src/particles/qquickimageparticle.cpp b/src/particles/qquickimageparticle.cpp
index 0bea3a87af..e5845f4c62 100644
--- a/src/particles/qquickimageparticle.cpp
+++ b/src/particles/qquickimageparticle.cpp
@@ -715,7 +715,6 @@ QQuickImageParticle::QQuickImageParticle(QQuickItem* parent)
     , m_sizeTable(0)
     , m_opacityTable(0)
     , m_color_variation(0.0)
-    , m_rootNode(0)
     , m_material(0)
     , m_alphaVariation(0.0)
     , m_alpha(1.0)
@@ -757,7 +756,6 @@ QQmlListProperty<QQuickSprite> QQuickImageParticle::sprites()
 void QQuickImageParticle::sceneGraphInvalidated()
 {
     m_nodes.clear();
-    m_rootNode = 0;
     m_material = 0;
 }
 
@@ -1209,24 +1207,25 @@ void QQuickImageParticle::mainThreadFetchImageData()
     m_startedImageLoading = 2;
 }
 
-void QQuickImageParticle::buildParticleNodes()
+void QQuickImageParticle::buildParticleNodes(QSGNode** passThrough)
 {
     // Starts async parts, like loading images, on gui thread
     // Not on individual properties, because we delay until system is running
-    if (m_rootNode || loadingSomething())
+    if (*passThrough || loadingSomething())
         return;
 
     if (m_startedImageLoading == 0) {
         m_startedImageLoading = 1;
+        //stage 1 is in gui thread
         QQuickImageParticle::staticMetaObject.invokeMethod(this, "mainThreadFetchImageData", Qt::QueuedConnection);
-    } else if (m_startedImageLoading == 2) { //stage 1 is in gui thread
-        finishBuildParticleNodes(); //rest happens in render thread
+    } else if (m_startedImageLoading == 2) {
+        finishBuildParticleNodes(passThrough); //rest happens in render thread
     }
 
     //No mutex, because it's slow and a compare that fails due to a race condition means just a dropped frame
 }
 
-void QQuickImageParticle::finishBuildParticleNodes()
+void QQuickImageParticle::finishBuildParticleNodes(QSGNode** node)
 {
 #ifdef QT_OPENGL_ES_2
     if (m_count * 4 > 0xffff) {
@@ -1456,17 +1455,18 @@ void QQuickImageParticle::finishBuildParticleNodes()
             (*(m_nodes.begin()))->appendChildNode(node);
     }
 
-    m_rootNode = *(m_nodes.begin());
+    *node = *(m_nodes.begin());
     update();
 }
 
-QSGNode *QQuickImageParticle::updatePaintNode(QSGNode *, UpdatePaintNodeData *)
+QSGNode *QQuickImageParticle::updatePaintNode(QSGNode *node, UpdatePaintNodeData *)
 {
     if (m_pleaseReset){
-        m_lastLevel = perfLevel;
+        if (node)
+            delete node;
+        node = 0;
 
-        delete m_rootNode;//Automatically deletes children, and SG manages material lifetime
-        m_rootNode = 0;
+        m_lastLevel = perfLevel;
         m_nodes.clear();
 
         m_idxStarts.clear();
@@ -1480,23 +1480,23 @@ QSGNode *QQuickImageParticle::updatePaintNode(QSGNode *, UpdatePaintNodeData *)
     }
 
     if (m_system && m_system->isRunning() && !m_system->isPaused()){
-        prepareNextFrame();
-        if (m_rootNode) {
+        prepareNextFrame(&node);
+        if (node) {
             update();
-            foreach (QSGGeometryNode* node, m_nodes)
-                node->markDirty(QSGNode::DirtyGeometry);
+            foreach (QSGGeometryNode* n, m_nodes)
+                n->markDirty(QSGNode::DirtyGeometry);
         } else if (m_startedImageLoading < 2) {
             update();//To call prepareNextFrame() again from the renderThread
         }
     }
 
-    return m_rootNode;
+    return node;
 }
 
-void QQuickImageParticle::prepareNextFrame()
+void QQuickImageParticle::prepareNextFrame(QSGNode **node)
 {
-    if (m_rootNode == 0){//TODO: Staggered loading (as emitted)
-        buildParticleNodes();
+    if (*node == 0){//TODO: Staggered loading (as emitted)
+        buildParticleNodes(node);
         if (m_debugMode) {
             qDebug() << "QQuickImageParticle Feature level: " << perfLevel;
             qDebug() << "QQuickImageParticle Nodes: ";
@@ -1507,7 +1507,7 @@ void QQuickImageParticle::prepareNextFrame()
             }
             qDebug() << "Total count: " << count;
         }
-        if (m_rootNode == 0)
+        if (*node == 0)
             return;
     }
     qint64 timeStamp = m_system->systemSync(this);