handle now also section view, detail view and view

src/Mod/TechDraw/Gui/ViewProviderProjGroupItem.cpp

@@ -149,7 +149,10 @@ bool ViewProviderProjGroupItem::doubleClicked(void)
 bool ViewProviderProjGroupItem::onDelete(const std::vector<std::string> &)
 {
     // we cannot delete the anchor view, thus check if the item is the front item
+    // we also cannot delete if the item has a section or detail view
 
+    QString bodyMessage;
+    QTextStream bodyMessageStream(&bodyMessage);
     bool isAnchor = false;
 
     // get the item and group
@@ -162,22 +165,40 @@ bool ViewProviderProjGroupItem::onDelete(const std::vector<std::string> &)
         && (dpg->getAnchor() == dpgi))
         isAnchor = true;
 
+    // get child views
+    auto viewSection = getObject()->getSectionRefs();
+    auto viewDetail = getObject()->getDetailRefs();
+
    if (isAnchor)
    {
        // generate dialog
-        QString bodyMessage;
-        QTextStream bodyMessageStream(&bodyMessage);
         bodyMessageStream << qApp->translate("Std_Delete",
-            "You cannot delete the anchor view of a projection group!");
+            "You cannot delete the anchor view of a projection group.");
         QMessageBox::warning(Gui::getMainWindow(),
             qApp->translate("Std_Delete", "Object dependencies"), bodyMessage,
             QMessageBox::Ok);
         // don't allow to delete
         return false;
-    }
-    else {
+   }
+   else if (!viewSection.empty()) {
+       bodyMessageStream << qApp->translate("Std_Delete",
+           "You cannot delete this view because it has a section view that would become broken.");
+       QMessageBox::warning(Gui::getMainWindow(),
+           qApp->translate("Std_Delete", "Object dependencies"), bodyMessage,
+           QMessageBox::Ok);
+       return false;
+   }
+   else if (!viewDetail.empty()) {
+       bodyMessageStream << qApp->translate("Std_Delete",
+           "You cannot delete this view because it has a detail view that would become broken.");
+       QMessageBox::warning(Gui::getMainWindow(),
+           qApp->translate("Std_Delete", "Object dependencies"), bodyMessage,
+           QMessageBox::Ok);
+       return false;
+   }
+   else {
         return true;
-    }
+   }
 }
 
 bool ViewProviderProjGroupItem::canDelete(App::DocumentObject *obj) const

src/Mod/TechDraw/Gui/ViewProviderViewPart.cpp

@@ -23,6 +23,8 @@
 #include "PreCompiled.h"
 
 #ifndef _PreComp_
+#include <QMessageBox>
+#include <QTextStream>
 # ifdef FC_OS_WIN32
 #  include <windows.h>
 # endif
@@ -35,6 +37,7 @@
 #include <App/Application.h>
 #include <App/Document.h>
 #include <App/DocumentObject.h>
+#include <Gui/MainWindow.h>
 
 #include <Mod/TechDraw/App/DrawViewDimension.h>
 #include <Mod/TechDraw/App/DrawViewBalloon.h>
@@ -246,3 +249,43 @@ void ViewProviderViewPart::handleChangedPropertyType(Base::XMLReader &reader, co
         ExtraWidth.setValue(ExtraWidthProperty.getValue());
     }
 }
+
+bool ViewProviderViewPart::onDelete(const std::vector<std::string> &)
+{
+    // we cannot delete if the view has a section or detail view
+
+    QString bodyMessage;
+    QTextStream bodyMessageStream(&bodyMessage);
+
+    // get child views
+    auto viewSection = getViewObject()->getSectionRefs();
+    auto viewDetail = getViewObject()->getDetailRefs();
+    
+    if (!viewSection.empty()) {
+        bodyMessageStream << qApp->translate("Std_Delete",
+            "You cannot delete this view because it has a section view that would become broken.");
+        QMessageBox::warning(Gui::getMainWindow(),
+            qApp->translate("Std_Delete", "Object dependencies"), bodyMessage,
+            QMessageBox::Ok);
+        return false;
+    }
+    else if (!viewDetail.empty()) {
+        bodyMessageStream << qApp->translate("Std_Delete",
+            "You cannot delete this view because it has a detail view that would become broken.");
+        QMessageBox::warning(Gui::getMainWindow(),
+            qApp->translate("Std_Delete", "Object dependencies"), bodyMessage,
+            QMessageBox::Ok);
+        return false;
+    }
+    else {
+        return true;
+    }
+}
+
+bool ViewProviderViewPart::canDelete(App::DocumentObject *obj) const
+{
+    // deletions of part objects (detail view, View etc.) are valid
+    // that it cannot be deleted if it has a child view is handled in the onDelete() function
+    Q_UNUSED(obj)
+    return true;
+}

src/Mod/TechDraw/Gui/ViewProviderViewPart.h

@@ -60,6 +60,8 @@ public:
     virtual bool useNewSelectionModel(void) const {return false;}
     /// returns a list of all possible modes
     virtual std::vector<std::string> getDisplayModes(void) const;
+    virtual bool onDelete(const std::vector<std::string> &);
+    virtual bool canDelete(App::DocumentObject* obj) const;
 
 public:
     virtual void onChanged(const App::Property *prop);

src/Mod/TechDraw/Gui/ViewProviderViewSection.cpp

@@ -187,6 +187,14 @@ void ViewProviderViewSection::getParameters(void)
     WeightPattern.setValue(lineWeight);
 }
 
+bool ViewProviderViewSection::canDelete(App::DocumentObject *obj) const
+{
+    // a section view can be deleted
+    // that its base view cannot be deleted is handled in its the onDelete() function
+    Q_UNUSED(obj)
+    return true;
+}
+
 TechDraw::DrawViewSection* ViewProviderViewSection::getViewObject() const
 {
     return dynamic_cast<TechDraw::DrawViewSection*>(pcObject);

src/Mod/TechDraw/Gui/ViewProviderViewSection.h

@@ -65,8 +65,7 @@ public:
 
     void updateGraphic(void);
     void getParameters(void);
-
-
+    virtual bool canDelete(App::DocumentObject* obj) const;
 
     virtual TechDraw::DrawViewSection* getViewObject() const;
 };