[TD]fix segfault on repeated open/close

[TD]fix memory leak in ViewProviderPage

[TD]fix QGView redraws at idle

src/Mod/TechDraw/Gui/MDIViewPage.cpp

@@ -153,6 +153,7 @@ void MDIViewPage::setScene(QGSPage* scene, QGVPage* viewWidget)
 void MDIViewPage::setDocumentObject(const std::string& name)
 {
     m_objectName = name;
+    setObjectName(Base::Tools::fromStdString(name));
 }
 
 void MDIViewPage::setDocumentName(const std::string& name)
@@ -162,6 +163,7 @@ void MDIViewPage::setDocumentName(const std::string& name)
 
 void MDIViewPage::closeEvent(QCloseEvent* ev)
 {
+//    Base::Console().Message("MDIVP::closeEvent()\n");
     MDIView::closeEvent(ev);
     if (!ev->isAccepted())
         return;

src/Mod/TechDraw/Gui/MDIViewPage.h

@@ -91,6 +91,7 @@ public:
 
     void setDocumentObject(const std::string&);
     void setDocumentName(const std::string&);
+
     PyObject* getPyObject() override;
     TechDraw::DrawPage * getPage() { return m_vpPage->getDrawPage(); }
 
@@ -138,11 +139,11 @@ private:
     std::string m_objectName;
     std::string m_documentName;
     bool isSelectionBlocked;
-    QGSPage* m_scene;
-    QGVPage *m_view;
+    QPointer<QGSPage> m_scene;
+    QPointer<QGVPage> m_view;
 
     QString m_currentPath;
-    ViewProviderPage *m_vpPage;
+    ViewProviderPage* m_vpPage;
 
     QList<QGraphicsItem*> m_qgSceneSelected;        //items in selection order
 

src/Mod/TechDraw/Gui/QGSPage.cpp

@@ -134,6 +134,8 @@ QGSPage::QGSPage(ViewProviderPage *vp, QWidget *parent)
 {
     assert(vp);
     m_vpPage = vp;
+    setItemIndexMethod(QGraphicsScene::BspTreeIndex);  //the default
+//    setItemIndexMethod(QGraphicsScene::NoIndex);    //sometimes faster
 }
 
 QGSPage::~QGSPage()

src/Mod/TechDraw/Gui/QGVPage.cpp

@@ -251,11 +251,10 @@ QGVPage::QGVPage(ViewProviderPage *vp, QGSPage* s, QWidget *parent)
     m_parentMDI = static_cast<MDIViewPage*>(parent);
     m_saveContextEvent = nullptr;
 
-    setViewportUpdateMode(QGraphicsView::FullViewportUpdate); //this prevents crash when deleting dims.
-                                                          //scene(view?) indices of dirty regions gets
-                                                          //out of sync.  missing prepareGeometryChange
-                                                          //somewhere???? QTBUG-18021????
     setCacheMode(QGraphicsView::CacheBackground);
+    setRenderer(Native);
+//    setRenderer(OpenGL);  //gives rotten quality, don't use this
+    setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
 
     d->init();
     if (m_atCursor) {
@@ -270,8 +269,6 @@ QGVPage::QGVPage(ViewProviderPage *vp, QGSPage* s, QWidget *parent)
 //    setDragMode(ScrollHandDrag);
     setDragMode(QGraphicsView::NoDrag);
     resetCursor();
-    setRenderer(Native);
-    setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform);
 
     bkgBrush = new QBrush(getBackgroundColor());
 
@@ -279,8 +276,6 @@ QGVPage::QGVPage(ViewProviderPage *vp, QGSPage* s, QWidget *parent)
     balloonCursor->setPixmap(prepareCursorPixmap("TechDraw_Balloon.svg", balloonHotspot = QPoint(8, 59)));
     balloonCursor->hide();
 
-    resetCachedContent();
-
     initNavigationStyle();
 
     createStandardCursors(devicePixelRatio());
@@ -294,8 +289,7 @@ QGVPage::~QGVPage()
 
 void QGVPage::centerOnPage(void)
 {
-//    Base::Console().Message("QGVP::centerOnPage()\n");
-    centerOn(m_scene->getTemplateCenter());
+    centerOn(m_vpPage->getGraphicsScene()->getTemplateCenter());
 }
 
 void QGVPage::initNavigationStyle()
@@ -382,8 +376,6 @@ void QGVPage::drawBackground(QPainter *p, const QRectF &)
     p->save();
     p->resetTransform();
 
-    resetCachedContent();
-
     p->setBrush(*bkgBrush);
     p->drawRect(viewport()->rect().adjusted(-2,-2,2,2));   //just bigger than viewport to prevent artifacts
 
@@ -405,7 +397,6 @@ void QGVPage::drawBackground(QPainter *p, const QRectF &)
     p->setBrush(pageBrush);
 
     p->drawRect(poly.boundingRect());
-    resetCachedContent();
 
     p->restore();
 }
@@ -416,10 +407,13 @@ void QGVPage::setRenderer(RendererType type)
 
     if (m_renderer == OpenGL) {
 #ifndef QT_NO_OPENGL
-        setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers)));
+//        setViewport(new QGLWidget(QGLFormat(QGL::SampleBuffers))); //QGLWidget is obsolete
+        setViewport(new QOpenGLWidget);
+        setViewportUpdateMode(QGraphicsView::SmartViewportUpdate);
 #endif
     } else {
         setViewport(new QWidget);
+        setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
     }
 }
 

src/Mod/TechDraw/Gui/ViewProviderPage.cpp

@@ -103,6 +103,7 @@ ViewProviderPage::ViewProviderPage()
 ViewProviderPage::~ViewProviderPage()
 {
     removeMDIView();                    //if the MDIViewPage is still in MainWindow, remove it.
+    m_graphicsScene->deleteLater();
 }
 
 void ViewProviderPage::attach(App::DocumentObject *pcFeat)
@@ -269,14 +270,12 @@ bool ViewProviderPage::doubleClicked(void)
 
 void ViewProviderPage::show(void)
 {
-//    Base::Console().Message("VPP::show()\n");
     showMDIViewPage();
     ViewProviderDocumentObject::show();
 }
 
 void ViewProviderPage::hide(void)
 {
-//    Base::Console().Message("VPP::hide()\n");
     if (getMDIView()) {
         getMDIView()->hide();     //this doesn't remove the mdiViewPage from the mainWindow
         removeMDIView();
@@ -303,12 +302,13 @@ bool ViewProviderPage::showMDIViewPage()
 
     setGrid();
 
+    Visibility.setValue(true);
+
     return true;
 }
 
 void ViewProviderPage::createMDIViewPage()
 {
-//    Base::Console().Message("VPP::createMDIViewPage()\n");
     Gui::Document* doc = Gui::Application::Instance->getDocument
         (pcObject->getDocument());
     m_mdiView = new MDIViewPage(this, doc, Gui::getMainWindow());
@@ -318,7 +318,6 @@ void ViewProviderPage::createMDIViewPage()
         m_graphicsView->setObjectName(QString::fromLocal8Bit(objName.c_str()));
     }
     m_mdiView->setScene(m_graphicsScene, m_graphicsView);
-    m_graphicsScene->setParent(m_graphicsView);   //for QObjectParent.  required??
     QString tabTitle = QString::fromUtf8(getDrawPage()->Label.getValue());
 
     m_mdiView->setDocumentObject(getDrawPage()->getNameInDocument());
@@ -330,20 +329,16 @@ void ViewProviderPage::createMDIViewPage()
     Gui::getMainWindow()->setActiveWindow(m_mdiView);
 }
 
-//NOTE: removing MDIViewPage (parent) destroys QGVPage which will
-//delete QGSPage if still parented to QGVPage
+//NOTE: removing MDIViewPage (parent) destroys QGVPage (eventually)
 void ViewProviderPage::removeMDIView(void)
 {
-//    Base::Console().Message("VPP::removeMDIViewPage()\n");
     if (!m_mdiView.isNull()) {                                //m_mdiView is a QPointer
-        // https://forum.freecadweb.org/viewtopic.php?f=3&t=22797&p=182614#p182614
-        //Gui::getMainWindow()->activatePreviousWindow();
         QList<QWidget*> wList= Gui::getMainWindow()->windows();
         bool found = wList.contains(m_mdiView);
         if (found) {
-            m_graphicsScene->setParent(nullptr);
             Gui::getMainWindow()->removeWindow(m_mdiView);
-            m_graphicsView = nullptr;       //m_graphicsView has been deleted by m_mdiView
+            m_mdiView = nullptr;            //m_mdiView will eventually be deleted and
+            m_graphicsView = nullptr;       //will take m_graphicsView with it
             Gui::MDIView* aw = Gui::getMainWindow()->activeWindow();  //WF: this bit should be in the remove window logic, not here.
             if (aw != nullptr) {
                 aw->showMaximized();