[TD]fix crash when Section deleted during creation

- if the Section is deleted while the section dialog
  is still in progress, further processing in the
  dialog would cause a crash.
- should have "update intent" locks to prevent this

src/Mod/TechDraw/Gui/TaskSectionView.cpp

@@ -78,7 +78,8 @@ TaskSectionView::TaskSectionView(TechDraw::DrawViewPart* base) :
     m_section(nullptr),
     m_dirName(""),
     m_createMode(true),
-    m_saved(false)
+    m_saved(false),
+    m_abort(false)
 {
 //    Base::Console().Message("TSV::TSV() - create mode\n");
     if  (m_base == nullptr)  {
@@ -87,8 +88,12 @@ TaskSectionView::TaskSectionView(TechDraw::DrawViewPart* base) :
         Base::Console().Error((msg + "\n").c_str());
         return;
     }
+    m_sectionName = std::string();
+    m_doc         = m_base->getDocument();
+
     m_saveBaseName = m_base->getNameInDocument();
     m_savePageName = m_base->findParentPage()->getNameInDocument();
+
  
    ui->setupUi(this);
 
@@ -113,9 +118,9 @@ TaskSectionView::TaskSectionView(TechDraw::DrawViewSection* section) :
     m_base(nullptr),
     m_section(section),
     m_createMode(false),
-    m_saved(false)
+    m_saved(false),
+    m_abort(false)
 {
-//    Base::Console().Message("TS::TS() - edit mode\n");
 
     if  (m_section == nullptr)  {
         //should be caught in CMD caller
@@ -124,6 +129,7 @@ TaskSectionView::TaskSectionView(TechDraw::DrawViewSection* section) :
         return;
     }
 
+    m_sectionName = m_section->getNameInDocument();
     App::DocumentObject* newObj = m_section->BaseView.getValue();
     m_base = dynamic_cast<TechDraw::DrawViewPart*>(newObj);
     if ( (newObj == nullptr) ||
@@ -229,7 +235,6 @@ void TaskSectionView::blockButtons(bool b)
     Q_UNUSED(b);
 }
 
-// cardinal: 0 - left, 1 - right, 2 - up, 3 - down
 void TaskSectionView::onUpClicked(bool b)
 {
 //    Base::Console().Message("TSV::onUpClicked()\n");
@@ -274,29 +279,6 @@ void TaskSectionView::onApplyClicked(bool b)
     apply();
 }
 
-bool TaskSectionView::apply(void)
-{
-//    Base::Console().Message("TSV::apply() - m_dirName: %s\n", m_dirName.c_str());
-    if (m_dirName.empty()) {
-        std::string msg = Base::Tools::toStdString(tr("TaskSectionView::apply - No section direction picked yet"));
-        Base::Console().Error((msg + "\n").c_str());
-        return false;
-    }
-    if (m_section == nullptr) {
-        return false;
-    }
-    App::Document* doc = m_section->getDocument();
-    App::DocumentObject* baseObj = doc->getObject(m_saveBaseName.c_str());
-    TechDraw::DrawViewPart* dvp = dynamic_cast<TechDraw::DrawViewPart*>(baseObj);
-    if (dvp == nullptr) {
-        return false;
-    }
-
-    checkAll(false);
-    applyQuick(m_dirName);
-    return true;
-}
-
 void TaskSectionView::checkAll(bool b)
 {
     ui->pbUp->setChecked(b);
@@ -306,20 +288,42 @@ void TaskSectionView::checkAll(bool b)
 }
 
 //******************************************************************************
+bool TaskSectionView::apply(void)
+{
+//    Base::Console().Message("TSV::apply() - m_dirName: %s\n", m_dirName.c_str());
+    if (m_dirName.empty()) {
+        std::string msg = 
+            Base::Tools::toStdString(tr("TSV::apply - Nothing to apply. No section direction picked yet"));
+        Base::Console().Error((msg + "\n").c_str());
+        return false;
+    }
+    if (m_section == nullptr) {          //didn't create the feature yet
+        return false;
+    }
+
+    checkAll(false);
+    applyQuick(m_dirName);
+    return true;
+}
+
 void TaskSectionView::applyQuick(std::string dir)
 {
 //    Base::Console().Message("TSV::applyQuick(%s)\n", dir.c_str());
     Gui::Command::openCommand("Apply Quick");
     m_dirName = dir;
     if (m_section == nullptr) {
-        m_section = createSectionView();
+        createSectionView();
     }
-    if (m_section != nullptr) {
+    if (isSectionValid()) {
         updateSectionView();
-       m_section->recomputeFeature();
+        m_section->recomputeFeature();
+    } else {
+        failNoObject(m_sectionName);
     }
-    if (m_base != nullptr) {
+
+    if (isBaseValid()) {
         m_base->requestPaint();
+        return;
     }
 }
 
@@ -330,18 +334,19 @@ void TaskSectionView::applyAligned(void)
     m_dirName = "Aligned";
     //fiddle with directions here
 
-//    m_section->recomputeFeature(); //????
     m_section->requestPaint();
     m_base->requestPaint();
 }
 
-TechDraw::DrawViewSection* TaskSectionView::createSectionView(void)
+//*********************************************************************
+
+//pointer to created view is not returned, but stored in m_section
+void TaskSectionView::createSectionView(void)
 {
 //    Base::Console().Message("TSV::createSectionView()\n");
-
-    if (m_base == nullptr) {
-        Base::Console().Error("TSV::createSectionView - base object not found!\n");
-        return nullptr;
+    if (!isBaseValid()) {
+        failNoObject(m_baseName);
+        return;
     }
 
     std::string sectionName;
@@ -349,134 +354,160 @@ TechDraw::DrawViewSection* TaskSectionView::createSectionView(void)
     double baseScale = m_base->getScale();
 
     Gui::Command::openCommand("Create SectionView");
-    TechDraw::DrawViewSection* newSection = nullptr;
     if (m_section == nullptr) {
-        sectionName = m_base->getDocument()->getUniqueObjectName("SectionView");
+        m_sectionName = m_base->getDocument()->getUniqueObjectName("SectionView");
         std::string sectionType = "TechDraw::DrawViewSection";
 
-        TechDraw::DrawPage* page = m_base->findParentPage();
-        std::string pageName = page->getNameInDocument();
-
         Command::doCommand(Command::Doc,"App.activeDocument().addObject('%s','%s')",
-                           sectionType.c_str(),sectionName.c_str());
+                           sectionType.c_str(),m_sectionName.c_str());
         Command::doCommand(Command::Doc,"App.activeDocument().%s.addView(App.activeDocument().%s)",
-                           pageName.c_str(), sectionName.c_str());
+                           m_savePageName.c_str(), m_sectionName.c_str());
         Command::doCommand(Command::Doc,"App.activeDocument().%s.BaseView = App.activeDocument().%s",
-                           sectionName.c_str(),baseName.c_str());
+                           m_sectionName.c_str(),baseName.c_str());
         Command::doCommand(Command::Doc,"App.activeDocument().%s.Source = App.activeDocument().%s.Source",
-                           sectionName.c_str(),baseName.c_str());
+                           m_sectionName.c_str(),baseName.c_str());
+        Command::doCommand(Command::Doc,
+                           "App.activeDocument().%s.SectionOrigin = FreeCAD.Vector(%.3f,%.3f,%.3f)",
+                           m_sectionName.c_str(), 
+                           ui->sbOrgX->value().getValue(),
+                           ui->sbOrgY->value().getValue(),
+                           ui->sbOrgZ->value().getValue());
         Command::doCommand(Command::Doc,"App.activeDocument().%s.Scale = %0.6f",
-                           sectionName.c_str(), baseScale);
+                           m_sectionName.c_str(), baseScale);
 
-        App::DocumentObject* newObj = m_base->getDocument()->getObject(sectionName.c_str());
-        newSection = dynamic_cast<TechDraw::DrawViewSection*>(newObj);
+        App::DocumentObject* newObj = m_base->getDocument()->getObject(m_sectionName.c_str());
+        m_section = dynamic_cast<TechDraw::DrawViewSection*>(newObj);
         if ( (newObj == nullptr) ||
-             (newSection == nullptr) ) {
+             (m_section == nullptr) ) {
             throw Base::RuntimeError("TaskSectionView - new section object not found");
          }
     }
-    return newSection;
+    Gui::Command::updateActive();
+    Gui::Command::commitCommand();
+
+    return;
 }
 
 void TaskSectionView::updateSectionView(void)
 {
-//    Base::Console().Message("TSV::updateSectionView()\n");
+//    Base::Console().Message("TSV::updateSectionView() - m_sectionName: %s\n", m_sectionName.c_str());
+    if (!isSectionValid()) {
+        failNoObject(m_sectionName);
+        return;
+    }
+
     if (m_section != nullptr) {
-        std::string sectionName = m_section->getNameInDocument();
         Command::doCommand(Command::Doc,"App.activeDocument().%s.SectionDirection = '%s'",
-                           sectionName.c_str(),m_dirName.c_str());
+                           m_sectionName.c_str(),m_dirName.c_str());
         Command::doCommand(Command::Doc,
                            "App.activeDocument().%s.SectionOrigin = FreeCAD.Vector(%.3f,%.3f,%.3f)",
-                           sectionName.c_str(), 
+                           m_sectionName.c_str(), 
                            ui->sbOrgX->value().getValue(),
                            ui->sbOrgY->value().getValue(),
                            ui->sbOrgZ->value().getValue());
         QString qTemp    = ui->leSymbol->text();
         std::string temp = Base::Tools::toStdString(qTemp);
         Command::doCommand(Command::Doc,"App.activeDocument().%s.SectionSymbol = '%s'",
-                           sectionName.c_str(),
+                           m_sectionName.c_str(),
                            temp.c_str());
         std::string lblText = "Section " +
                               temp + 
                               " - " +
                               temp;
         Command::doCommand(Command::Doc,"App.activeDocument().%s.Label = '%s'",
-                           sectionName.c_str(),
+                           m_sectionName.c_str(),
                            lblText.c_str());
         Command::doCommand(Command::Doc,"App.activeDocument().%s.Scale = %0.6f",
-                           sectionName.c_str(),
+                           m_sectionName.c_str(),
                            ui->sbScale->value());
         m_section->setCSFromBase(m_dirName.c_str());
     }
 }
 
+void TaskSectionView::failNoObject(std::string objectName) 
+{
+    QString qObjectName = Base::Tools::fromStdString(objectName);
+    QString msg = tr("Can not continue. Object * %1 * not found.").arg(qObjectName);
+    QMessageBox::critical(Gui::getMainWindow(), QObject::tr("Operation Failed"), msg);
+    Gui::Control().closeDialog();
+    m_abort = true;
+}
+
+bool TaskSectionView::isBaseValid(void)
+{
+    bool result = true;
+    if (m_base == nullptr) {
+        result = false;
+    } else {
+        App::DocumentObject* baseObj = m_doc->getObject(m_saveBaseName.c_str());
+        if (baseObj == nullptr) {
+            result = false;
+        }
+    }
+    return result;
+}
+
+bool TaskSectionView::isSectionValid(void)
+{
+    bool result = true;
+    if (m_section == nullptr) {
+        result = false;
+    } else {
+        App::DocumentObject* sectionObj = m_doc->getObject(m_sectionName.c_str());
+        if (sectionObj == nullptr) {
+            result = false;
+        }
+    }
+    return result;
+}
 
 //******************************************************************************
 
 bool TaskSectionView::accept()
 {
 //    Base::Console().Message("TSV::accept()\n");
-    if (m_createMode) {
-        if (m_section == nullptr) {
-            apply();
-        } else {
-            updateSectionView();
-        }
-        Gui::Command::updateActive();
-        Gui::Command::commitCommand();
-    } else {
-        Gui::Command::openCommand("Edit SectionView");
-        try {
-            updateSectionView();
-        }
-        catch (...) {
-            Base::Console().Error("TSV::accept - failed to update section\n");
-        }
-
-        Gui::Command::updateActive();
-        Gui::Command::commitCommand();
+    if (m_abort) {
+        return true;
     }
+    apply();
     Gui::Command::doCommand(Gui::Command::Gui,"Gui.ActiveDocument.resetEdit()");
-    if (m_section != nullptr) {
-        m_section->requestPaint();
-        App::Document* doc = m_section->getDocument();
-        App::DocumentObject* baseObj = doc->getObject(m_saveBaseName.c_str());
-        TechDraw::DrawViewPart* dvp = dynamic_cast<TechDraw::DrawViewPart*>(baseObj);
-        if (dvp != nullptr) {
-            dvp->requestPaint();
-        }
-    }
     return true;
 }
 
 bool TaskSectionView::reject()
 {
 //    Base::Console().Message("TSV::reject()\n");
-    if (m_section != nullptr) {
-        if (m_createMode) {
-            std::string SectionName = m_section->getNameInDocument();
-            Gui::Command::doCommand(Gui::Command::Gui,
-                                    "App.activeDocument().%s.removeView(App.activeDocument().%s)",
-                                    m_savePageName.c_str(),SectionName.c_str());
-            Gui::Command::doCommand(Gui::Command::Gui,
-                                    "App.activeDocument().removeObject('%s')",
-                                    SectionName.c_str());
-        } else {
-            restoreSectionState();
-            //check undo stack?
-            if (m_section != nullptr) {
-                m_section->requestPaint();
-                App::Document* doc = m_section->getDocument();
-                App::DocumentObject* baseObj = doc->getObject(m_saveBaseName.c_str());
-                TechDraw::DrawViewPart* dvp = dynamic_cast<TechDraw::DrawViewPart*>(baseObj);
-                if (dvp != nullptr) {
-                    dvp->requestPaint();
-                }
-            }
-        }
+    if (m_section == nullptr) {                 //no section created, nothing to undo
+        Gui::Command::doCommand(Gui::Command::Gui,"Gui.ActiveDocument.resetEdit()");
+        return false;
+    }
+
+    if (!isSectionValid()) {                    //section !exist. nothing to undo 
+        if (isBaseValid()) {
+            m_base->requestPaint();
+        }
+        Gui::Command::doCommand(Gui::Command::Gui,"Gui.ActiveDocument.resetEdit()");
+        return false;
+    }
+
+    if (m_createMode) {
+        std::string SectionName = m_section->getNameInDocument();
+        Gui::Command::doCommand(Gui::Command::Gui,
+                                "App.activeDocument().%s.removeView(App.activeDocument().%s)",
+                                m_savePageName.c_str(),SectionName.c_str());
+        Gui::Command::doCommand(Gui::Command::Gui,
+                                "App.activeDocument().removeObject('%s')",
+                                SectionName.c_str());
+    } else {
+        restoreSectionState();
+        m_section->recomputeFeature();
+        m_section->requestPaint();
+    }
+
+    if (isBaseValid()) {
+        m_base->requestPaint();
     }
 
-    Gui::Command::doCommand(Gui::Command::Gui,"App.activeDocument().recompute()");
     Gui::Command::doCommand(Gui::Command::Gui,"Gui.ActiveDocument.resetEdit()");
 
     return false;
@@ -529,13 +560,6 @@ bool TaskDlgSectionView::accept()
     return true;
 }
 
-//bool TaskDlgSectionView::apply()
-//{
-//    Base::Console().Message("TDSV::apply()\n");
-//    widget->apply();
-//    return true;
-//}
-
 bool TaskDlgSectionView::reject()
 {
     widget->reject();