QmlDesginer.statesEditor: avoid crashes during reattaching model

src/plugins/qmldesigner/components/stateseditor/stateseditorview.cpp

@@ -37,7 +37,7 @@
 #include <math.h>
 
 enum {
-    debug = false
+    debug = true
 };
 
 namespace QmlDesigner {
@@ -49,7 +49,8 @@ namespace Internal {
   */
 StatesEditorView::StatesEditorView(StatesEditorModel *editorModel, QObject *parent) :
         QmlModelView(parent),
-        m_editorModel(editorModel)
+        m_editorModel(editorModel),
+        m_attachedToModel(false)
 {
     Q_ASSERT(m_editorModel);
 }
@@ -79,7 +80,9 @@ void StatesEditorView::setCurrentState(int index)
     if (m_modelStates.isEmpty())
         return;
 
-    Q_ASSERT(index >= 0 && index < m_modelStates.count());
+    Q_ASSERT(index < m_modelStates.count());
+    if (index == -1)
+        return;
 
     if (m_modelStates.indexOf(currentState()) == index)
         return;
@@ -174,6 +177,7 @@ void StatesEditorView::modelAttached(Model *model)
         return;
 
     m_modelStates.insert(0, baseState());
+    m_attachedToModel = true;
     m_editorModel->insertState(0, baseState().name());
 
     // Add custom states
@@ -185,6 +189,7 @@ void StatesEditorView::modelAttached(Model *model)
         QmlModelState state = QmlItemNode(rootModelNode()).states().allStates().at(i);
         insertModelState(i, state);
     }
+
 }
 
 void StatesEditorView::modelAboutToBeDetached(Model *model)
@@ -192,6 +197,8 @@ void StatesEditorView::modelAboutToBeDetached(Model *model)
     if (debug)
         qDebug() << __FUNCTION__;
 
+    m_attachedToModel = false;
+
     clearModelStates();
 
     QmlModelView::modelAboutToBeDetached(model);
@@ -390,6 +397,9 @@ QPixmap StatesEditorView::renderState(int i)
     if (debug)
         qDebug() << __FUNCTION__ << i;
 
+    if (!m_attachedToModel)
+        return QPixmap();
+
     Q_ASSERT(i >= 0 && i < m_modelStates.size());
     nodeInstanceView()->setBlockChangeSignal(true);
     QmlModelState oldState = currentState();

src/plugins/qmldesigner/components/stateseditor/stateseditorview.h

@@ -53,6 +53,7 @@ public:
 
     QPixmap renderState(int i);
     QmlItemNode stateRootNode() { return m_stateRootNode; }
+    bool isAttachedToModel() const { return m_attachedToModel; }
 
 protected:
     // AbstractView
@@ -95,6 +96,7 @@ private:
 
     QList<int> m_updateTimerIdList;
     QmlModelState m_oldRewriterAmendState;
+    bool m_attachedToModel;
 };
 
 } // namespace Internal

src/plugins/qmldesigner/components/stateseditor/stateseditorwidget.cpp

@@ -115,7 +115,8 @@ bool StatesEditorWidgetPrivate::validStateName(const QString &name) const
 
 void StatesEditorWidgetPrivate::currentStateChanged()
 {
-    statesEditorView->setCurrentState(currentIndex());
+    if (statesEditorView->isAttachedToModel())
+        statesEditorView->setCurrentState(currentIndex());
 }
 
 void StatesEditorWidgetPrivate::addState()