Surface: add command to create surface from sections

src/Mod/Part/App/BSplineSurfacePyImp.cpp

@@ -1514,6 +1514,7 @@ PyObject* BSplineSurfacePy::buildFromPolesMultsKnots(PyObject *args, PyObject *k
 
 /*!
  * \code
+import math
 c = Part.Circle()
 c.Radius=50
 c = c.trim(0, math.pi)

src/Mod/Surface/App/AppSurface.cpp

@@ -33,6 +33,7 @@
 #include "FeatureCut.h"
 #include "FeatureGeomFillSurface.h"
 #include "FeatureExtend.h"
+#include "FeatureSections.h"
 
 #include <Base/Interpreter.h>
 #include <Base/Parameter.h>
@@ -80,6 +81,7 @@ PyMOD_INIT_FUNC(Surface)
     Surface::Cut             ::init();
     Surface::GeomFillSurface ::init();
     Surface::Extend          ::init();
+    Surface::Sections        ::init();
 
     PyMOD_Return(mod);
 }

src/Mod/Surface/App/CMakeLists.txt

@@ -27,6 +27,8 @@ SET(Surface_SRCS
     FeatureGeomFillSurface.h
     FeatureFilling.cpp
     FeatureFilling.h
+    FeatureSections.cpp
+    FeatureSections.h
     FeatureSewing.cpp
     FeatureSewing.h
     FeatureCut.cpp

src/Mod/Surface/App/FeatureSections.cpp

@@ -0,0 +1,103 @@
+/***************************************************************************
+ *   Copyright (c) 2020 Werner Mayer <wmayer[at]users.sourceforge.net>     *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  is distributed in the hope that it will be useful,      *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "PreCompiled.h"
+#ifndef _PreComp_
+#include <BRepAdaptor_Curve.hxx>
+#include <BRepBuilderAPI_MakeFace.hxx>
+#include <Geom_BSplineSurface.hxx>
+#include <Geom_TrimmedCurve.hxx>
+#include <GeomAdaptor_Curve.hxx>
+#include <GeomFill_NSections.hxx>
+#include <TopLoc_Location.hxx>
+#include <TopoDS.hxx>
+#include <TopoDS_Face.hxx>
+#include <Precision.hxx>
+#include <Standard_Version.hxx>
+#endif
+
+#include "FeatureSections.h"
+#include <Base/Tools.h>
+#include <Base/Exception.h>
+
+using namespace Surface;
+
+PROPERTY_SOURCE(Surface::Sections, Part::Spline)
+
+Sections::Sections()
+{
+    ADD_PROPERTY_TYPE(NSections,(nullptr), "Sections", App::Prop_None, "Section curves");
+    NSections.setScope(App::LinkScope::Global);
+}
+
+Sections::~Sections()
+{
+}
+
+App::DocumentObjectExecReturn *Sections::execute(void)
+{
+    TColGeom_SequenceOfCurve curveSeq;
+    auto edge_obj = NSections.getValues();
+    auto edge_sub = NSections.getSubValues();
+    if (edge_obj.size() == edge_sub.size()) {
+        for (std::size_t index = 0; index < edge_obj.size(); index++) {
+            // get the part object
+            App::DocumentObject* obj = edge_obj[index];
+            const std::string& sub = edge_sub[index];
+            if (obj && obj->getTypeId().isDerivedFrom(Part::Feature::getClassTypeId())) {
+                // get the sub-edge of the part's shape
+                const Part::TopoShape& shape = static_cast<Part::Feature*>(obj)->Shape.getShape();
+                TopoDS_Shape edge = shape.getSubShape(sub.c_str());
+                if (!edge.IsNull() && edge.ShapeType() == TopAbs_EDGE) {
+                    BRepAdaptor_Curve curve_adapt(TopoDS::Edge(edge));
+                    const TopLoc_Location& loc = edge.Location();
+                    Handle(Geom_TrimmedCurve) hCurve = new Geom_TrimmedCurve(curve_adapt.Curve().Curve(),
+                                                                             curve_adapt.FirstParameter(),
+                                                                             curve_adapt.LastParameter());
+                    if (!loc.IsIdentity()) {
+                        hCurve->Transform(loc.Transformation());
+                    }
+                    curveSeq.Append(hCurve);
+                }
+            }
+        }
+    }
+
+    if (curveSeq.Length() < 2)
+        return new App::DocumentObjectExecReturn("At least two sections are required.");
+
+    GeomFill_NSections fillOp(curveSeq);
+    fillOp.ComputeSurface();
+
+    Handle(Geom_BSplineSurface) aSurf = fillOp.BSplineSurface();
+    if (aSurf.IsNull())
+        return new App::DocumentObjectExecReturn("Failed to create surface from sections.");
+
+    BRepBuilderAPI_MakeFace mkFace(aSurf
+#if OCC_VERSION_HEX >= 0x060502
+      , Precision::Confusion()
+#endif
+    );
+
+    Shape.setValue(mkFace.Face());
+    return StdReturn;
+}

src/Mod/Surface/App/FeatureSections.h

@@ -0,0 +1,54 @@
+/***************************************************************************
+ *   Copyright (c) 2020 Werner Mayer <wmayer[at]users.sourceforge.net>     *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  is distributed in the hope that it will be useful,      *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef SURFACE_FEATURESECTIONS_H
+#define SURFACE_FEATURESECTIONS_H
+
+#include <App/PropertyStandard.h>
+#include <App/PropertyUnits.h>
+#include <App/PropertyLinks.h>
+#include <Mod/Part/App/FeaturePartSpline.h>
+
+namespace Surface
+{
+
+class SurfaceExport Sections :  public Part::Spline
+{
+    PROPERTY_HEADER_WITH_OVERRIDE(Surface::Sections);
+
+public:
+    Sections();
+    ~Sections();
+
+    App::PropertyLinkSubList NSections;
+
+    // recalculate the feature
+    App::DocumentObjectExecReturn *execute(void) override;
+    /// returns the type name of the view provider
+    const char* getViewProviderName(void) const override {
+        return "SurfaceGui::ViewProviderSections";
+    }
+};
+
+}//Namespace Surface
+
+#endif

src/Mod/Surface/App/PreCompiled.h

@@ -61,6 +61,7 @@
 
 //opencascade
 #include "OpenCascadeAll.h"
+#include <GeomFill_NSections.hxx>
 
 #endif //_PreComp_
 

src/Mod/Surface/Gui/AppSurfaceGui.cpp

@@ -36,6 +36,7 @@
 #include "Workbench.h"
 #include "TaskGeomFillSurface.h"
 #include "TaskFilling.h"
+#include "TaskSections.h"
 
 // use a different name to CreateCommand()
 void CreateSurfaceCommands(void);
@@ -79,6 +80,7 @@ PyMOD_INIT_FUNC(SurfaceGui)
     SurfaceGui::Workbench::init();
     SurfaceGui::ViewProviderGeomFillSurface ::init();
     SurfaceGui::ViewProviderFilling         ::init();
+    SurfaceGui::ViewProviderSections        ::init();
     
 //    SurfaceGui::ViewProviderCut::init();
 

src/Mod/Surface/Gui/CMakeLists.txt

@@ -28,6 +28,7 @@ set(SurfaceGui_MOC_HDRS
     TaskFillingUnbound.h
     TaskFillingVertex.h
     TaskGeomFillSurface.h
+    TaskSections.h
 )
 fc_wrap_cpp(SurfaceGui_MOC_SRCS ${SurfaceGui_MOC_HDRS})
 SOURCE_GROUP("Moc" FILES ${SurfaceGui_MOC_SRCS})
@@ -43,6 +44,7 @@ SET(SurfaceGui_UIC_SRCS
     TaskFillingUnbound.ui
     TaskFillingVertex.ui
     TaskGeomFillSurface.ui
+    TaskSections.ui
 )
 
 if (BUILD_QT5)
@@ -62,6 +64,8 @@ SET(SurfaceGui_SRCS
     TaskFillingVertex.h
     TaskGeomFillSurface.cpp
     TaskGeomFillSurface.h
+    TaskSections.cpp
+    TaskSections.h
     AppSurfaceGui.cpp
     Command.cpp
     PreCompiled.cpp

src/Mod/Surface/Gui/Command.cpp

@@ -261,6 +261,35 @@ bool CmdSurfaceExtendFace::isActive(void)
     return Gui::Selection().countObjectsOfType(Part::Feature::getClassTypeId()) == 1;
 }
 
+DEF_STD_CMD_A(CmdSurfaceSections)
+
+CmdSurfaceSections::CmdSurfaceSections()
+  :Command("Surface_Sections")
+{
+    sAppModule    = "Surface";
+    sGroup        = QT_TR_NOOP("Surface");
+    sMenuText     = QT_TR_NOOP("Sections...");
+    sToolTipText  = QT_TR_NOOP("Creates a surface from a series of section curves");
+    sStatusTip    = QT_TR_NOOP("Creates a surface from a series of section curves");
+    sWhatsThis    = "Surface_Sections";
+  //sPixmap       = "Surface_Sections";
+}
+
+void CmdSurfaceSections::activated(int iMsg)
+{
+    Q_UNUSED(iMsg);
+    std::string FeatName = getUniqueObjectName("Surface");
+
+    openCommand("Create surface");
+    doCommand(Doc, "App.ActiveDocument.addObject(\"Surface::Sections\",\"%s\")", FeatName.c_str());
+    doCommand(Doc, "Gui.ActiveDocument.setEdit('%s',0)", FeatName.c_str());
+}
+
+bool CmdSurfaceSections::isActive(void)
+{
+    return hasActiveDocument();
+}
+
 void CreateSurfaceCommands(void)
 {
     Gui::CommandManager &rcCmdMgr = Gui::Application::Instance->commandManager();
@@ -270,4 +299,5 @@ void CreateSurfaceCommands(void)
     rcCmdMgr.addCommand(new CmdSurfaceGeomFillSurface());
     rcCmdMgr.addCommand(new CmdSurfaceCurveOnMesh());
     rcCmdMgr.addCommand(new CmdSurfaceExtendFace());
+    rcCmdMgr.addCommand(new CmdSurfaceSections());
 }

src/Mod/Surface/Gui/TaskSections.cpp

@@ -0,0 +1,603 @@
+/***************************************************************************
+ *   Copyright (c) 2017 Werner Mayer <wmayer[at]users.sourceforge.net>     *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  is distributed in the hope that it will be useful,      *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "PreCompiled.h"
+#include <QAction>
+#include <QMenu>
+#include <QMessageBox>
+#include <QTimer>
+#include <GeomAbs_Shape.hxx>
+#include <TopExp.hxx>
+#include <TopTools_IndexedMapOfShape.hxx>
+#include <TopTools_IndexedDataMapOfShapeListOfShape.hxx>
+#include <TopTools_ListIteratorOfListOfShape.hxx>
+
+#include <Gui/ViewProvider.h>
+#include <Gui/Application.h>
+#include <Gui/Document.h>
+#include <Gui/Command.h>
+#include <Gui/SelectionObject.h>
+#include <Base/Console.h>
+#include <Gui/Control.h>
+#include <Gui/BitmapFactory.h>
+#include <Mod/Part/Gui/ViewProvider.h>
+
+#include "TaskSections.h"
+#include "ui_TaskSections.h"
+
+
+using namespace SurfaceGui;
+
+PROPERTY_SOURCE(SurfaceGui::ViewProviderSections, PartGui::ViewProviderSpline)
+
+namespace SurfaceGui {
+
+void ViewProviderSections::setupContextMenu(QMenu* menu, QObject* receiver, const char* member)
+{
+    QAction* act;
+    act = menu->addAction(QObject::tr("Edit sections"), receiver, member);
+    act->setData(QVariant((int)ViewProvider::Default));
+    PartGui::ViewProviderSpline::setupContextMenu(menu, receiver, member);
+}
+
+bool ViewProviderSections::setEdit(int ModNum)
+{
+    if (ModNum == ViewProvider::Default ) {
+        // When double-clicking on the item for this sketch the
+        // object unsets and sets its edit mode without closing
+        // the task panel
+
+        Surface::Sections* obj =  static_cast<Surface::Sections*>(this->getObject());
+
+        Gui::TaskView::TaskDialog* dlg = Gui::Control().activeDialog();
+
+        // start the edit dialog
+        if (dlg) {
+            TaskSections* tDlg = qobject_cast<TaskSections*>(dlg);
+            if (tDlg)
+                tDlg->setEditedObject(obj);
+            Gui::Control().showDialog(dlg);
+        }
+        else {
+            Gui::Control().showDialog(new TaskSections(this, obj));
+        }
+        return true;
+    }
+    else {
+        return ViewProviderSpline::setEdit(ModNum);
+    }
+}
+
+void ViewProviderSections::unsetEdit(int ModNum)
+{
+    if (ModNum == ViewProvider::Default) {
+        // when pressing ESC make sure to close the dialog
+        QTimer::singleShot(0, &Gui::Control(), SLOT(closeDialog()));
+    }
+    else {
+        PartGui::ViewProviderSpline::unsetEdit(ModNum);
+    }
+}
+
+QIcon ViewProviderSections::getIcon(void) const
+{
+    return Gui::BitmapFactory().pixmap("BSplineSurf");
+}
+
+void ViewProviderSections::highlightReferences(ShapeType type, const References& refs, bool on)
+{
+    for (auto it : refs) {
+        Part::Feature* base = dynamic_cast<Part::Feature*>(it.first);
+        if (base) {
+            PartGui::ViewProviderPartExt* svp = dynamic_cast<PartGui::ViewProviderPartExt*>(
+                        Gui::Application::Instance->getViewProvider(base));
+            if (svp) {
+                switch (type) {
+                case ViewProviderSections::Vertex:
+                    if (on) {
+                        std::vector<App::Color> colors;
+                        TopTools_IndexedMapOfShape vMap;
+                        TopExp::MapShapes(base->Shape.getValue(), TopAbs_VERTEX, vMap);
+                        colors.resize(vMap.Extent(), svp->PointColor.getValue());
+
+                        for (auto jt : it.second) {
+                            // check again that the index is in range because it's possible that the
+                            // sub-names are invalid
+                            std::size_t idx = static_cast<std::size_t>(std::stoi(jt.substr(6)) - 1);
+                            if (idx < colors.size())
+                                colors[idx] = App::Color(1.0,0.0,1.0); // magenta
+                        }
+
+                        svp->setHighlightedPoints(colors);
+                    }
+                    else {
+                        svp->unsetHighlightedPoints();
+                    }
+                    break;
+                case ViewProviderSections::Edge:
+                    if (on) {
+                        std::vector<App::Color> colors;
+                        TopTools_IndexedMapOfShape eMap;
+                        TopExp::MapShapes(base->Shape.getValue(), TopAbs_EDGE, eMap);
+                        colors.resize(eMap.Extent(), svp->LineColor.getValue());
+
+                        for (auto jt : it.second) {
+                            std::size_t idx = static_cast<std::size_t>(std::stoi(jt.substr(4)) - 1);
+                            // check again that the index is in range because it's possible that the
+                            // sub-names are invalid
+                            if (idx < colors.size())
+                                colors[idx] = App::Color(1.0,0.0,1.0); // magenta
+                        }
+
+                        svp->setHighlightedEdges(colors);
+                    }
+                    else {
+                        svp->unsetHighlightedEdges();
+                    }
+                    break;
+                case ViewProviderSections::Face:
+                    if (on) {
+                        std::vector<App::Color> colors;
+                        TopTools_IndexedMapOfShape fMap;
+                        TopExp::MapShapes(base->Shape.getValue(), TopAbs_FACE, fMap);
+                        colors.resize(fMap.Extent(), svp->ShapeColor.getValue());
+
+                        for (auto jt : it.second) {
+                            std::size_t idx = static_cast<std::size_t>(std::stoi(jt.substr(4)) - 1);
+                            // check again that the index is in range because it's possible that the
+                            // sub-names are invalid
+                            if (idx < colors.size())
+                                colors[idx] = App::Color(1.0,0.0,1.0); // magenta
+                        }
+
+                        svp->setHighlightedFaces(colors);
+                    }
+                    else {
+                        svp->unsetHighlightedFaces();
+                    }
+                    break;
+                }
+            }
+        }
+    }
+}
+
+// ----------------------------------------------------------------------------
+
+class SectionsPanel::ShapeSelection : public Gui::SelectionFilterGate
+{
+public:
+    ShapeSelection(SectionsPanel::SelectionMode& mode, Surface::Sections* editedObject)
+        : Gui::SelectionFilterGate(static_cast<Gui::SelectionFilter*>(nullptr))
+        , mode(mode)
+        , editedObject(editedObject)
+    {
+    }
+    ~ShapeSelection()
+    {
+        mode = SectionsPanel::None;
+    }
+    /**
+      * Allow the user to pick only edges.
+      */
+    bool allow(App::Document*, App::DocumentObject* pObj, const char* sSubName)
+    {
+        // don't allow references to itself
+        if (pObj == editedObject)
+            return false;
+        if (!pObj->isDerivedFrom(Part::Feature::getClassTypeId()))
+            return false;
+
+        if (!sSubName || sSubName[0] == '\0')
+            return false;
+
+        switch (mode) {
+        case SectionsPanel::AppendEdge:
+            return allowEdge(true, pObj, sSubName);
+        case SectionsPanel::RemoveEdge:
+            return allowEdge(false, pObj, sSubName);
+        default:
+            return false;
+        }
+    }
+
+private:
+    bool allowEdge(bool appendEdges, App::DocumentObject* pObj, const char* sSubName)
+    {
+        std::string element(sSubName);
+        if (element.substr(0,4) != "Edge")
+            return false;
+
+        auto links = editedObject->NSections.getSubListValues();
+        for (auto it : links) {
+            if (it.first == pObj) {
+                for (auto jt : it.second) {
+                    if (jt == sSubName)
+                        return !appendEdges;
+                }
+            }
+        }
+
+        return appendEdges;
+    }
+
+private:
+    SectionsPanel::SelectionMode& mode;
+    Surface::Sections* editedObject;
+};
+
+// ----------------------------------------------------------------------------
+
+SectionsPanel::SectionsPanel(ViewProviderSections* vp, Surface::Sections* obj) : ui(new Ui_Sections())
+{
+    ui->setupUi(this);
+    ui->statusLabel->clear();
+
+    selectionMode = None;
+    this->vp = vp;
+    checkCommand = true;
+    setEditedObject(obj);
+
+    // Create context menu
+    QAction* action = new QAction(tr("Remove"), this);
+    action->setShortcut(QKeySequence::Delete);
+    ui->listSections->addAction(action);
+    connect(action, SIGNAL(triggered()), this, SLOT(onDeleteEdge()));
+    ui->listSections->setContextMenuPolicy(Qt::ActionsContextMenu);
+
+    connect(ui->listSections->model(),
+        SIGNAL(rowsMoved(QModelIndex, int, int, QModelIndex, int)), this, SLOT(onIndexesMoved()));
+}
+
+/*
+ *  Destroys the object and frees any allocated resources
+ */
+SectionsPanel::~SectionsPanel()
+{
+}
+
+// stores object pointer, its old fill type and adjusts radio buttons according to it.
+void SectionsPanel::setEditedObject(Surface::Sections* fea)
+{
+    editedObject = fea;
+
+    // get the section edges
+    auto objects = editedObject->NSections.getValues();
+    auto edges = editedObject->NSections.getSubValues();
+    auto count = objects.size();
+
+    App::Document* doc = editedObject->getDocument();
+    for (std::size_t i=0; i<count; i++) {
+        App::DocumentObject* obj = objects[i];
+        std::string edge = edges[i];
+
+        QListWidgetItem* item = new QListWidgetItem(ui->listSections);
+        ui->listSections->addItem(item);
+
+        QString text = QString::fromLatin1("%1.%2")
+                .arg(QString::fromUtf8(obj->Label.getValue()))
+                .arg(QString::fromStdString(edge));
+        item->setText(text);
+
+        // The user data field of a list widget item
+        // is a list of five elementa:
+        // 1. document name
+        // 2. object name
+        // 3. sub-element name of the edge
+        QList<QVariant> data;
+        data << QByteArray(doc->getName());
+        data << QByteArray(obj->getNameInDocument());
+        data << QByteArray(edge.c_str());
+        item->setData(Qt::UserRole, data);
+    }
+
+    // attach this document observer
+    attachDocument(Gui::Application::Instance->getDocument(doc));
+}
+
+void SectionsPanel::changeEvent(QEvent *e)
+{
+    if (e->type() == QEvent::LanguageChange) {
+        ui->retranslateUi(this);
+    }
+    else {
+        QWidget::changeEvent(e);
+    }
+}
+
+void SectionsPanel::open()
+{
+    checkOpenCommand();
+
+    // highlight the boundary edges
+    this->vp->highlightReferences(ViewProviderSections::Edge,
+        editedObject->NSections.getSubListValues(), true);
+
+    Gui::Selection().clearSelection();
+}
+
+void SectionsPanel::clearSelection()
+{
+    Gui::Selection().clearSelection();
+}
+
+void SectionsPanel::checkOpenCommand()
+{
+    if (checkCommand && !Gui::Command::hasPendingCommand()) {
+        std::string Msg("Edit ");
+        Msg += editedObject->Label.getValue();
+        Gui::Command::openCommand(Msg.c_str());
+        checkCommand = false;
+    }
+}
+
+void SectionsPanel::slotUndoDocument(const Gui::Document&)
+{
+    checkCommand = true;
+}
+
+void SectionsPanel::slotRedoDocument(const Gui::Document&)
+{
+    checkCommand = true;
+}
+
+void SectionsPanel::slotDeletedObject(const Gui::ViewProviderDocumentObject& Obj)
+{
+    // If this view provider is being deleted then reset the colors of
+    // referenced part objects. The dialog will be deleted later.
+    if (this->vp == &Obj) {
+        this->vp->highlightReferences(ViewProviderSections::Edge,
+            editedObject->NSections.getSubListValues(), false);
+    }
+}
+
+bool SectionsPanel::accept()
+{
+    selectionMode = None;
+    Gui::Selection().rmvSelectionGate();
+
+    if (editedObject->mustExecute())
+        editedObject->recomputeFeature();
+    if (!editedObject->isValid()) {
+        QMessageBox::warning(this, tr("Invalid object"),
+            QString::fromLatin1(editedObject->getStatusString()));
+        return false;
+    }
+
+    this->vp->highlightReferences(ViewProviderSections::Edge,
+        editedObject->NSections.getSubListValues(), false);
+
+    return true;
+}
+
+bool SectionsPanel::reject()
+{
+    this->vp->highlightReferences(ViewProviderSections::Edge,
+        editedObject->NSections.getSubListValues(), false);
+
+    selectionMode = None;
+    Gui::Selection().rmvSelectionGate();
+
+    return true;
+}
+
+void SectionsPanel::on_buttonEdgeAdd_clicked()
+{
+    // 'selectionMode' is passed by reference and changed when the filter is deleted
+    Gui::Selection().addSelectionGate(new ShapeSelection(selectionMode, editedObject));
+    selectionMode = AppendEdge;
+}
+
+void SectionsPanel::on_buttonEdgeRemove_clicked()
+{
+    // 'selectionMode' is passed by reference and changed when the filter is deleted
+    Gui::Selection().addSelectionGate(new ShapeSelection(selectionMode, editedObject));
+    selectionMode = RemoveEdge;
+}
+
+void SectionsPanel::onSelectionChanged(const Gui::SelectionChanges& msg)
+{
+    if (selectionMode == None)
+        return;
+
+    if (msg.Type == Gui::SelectionChanges::AddSelection) {
+        checkOpenCommand();
+        if (selectionMode == AppendEdge) {
+            QListWidgetItem* item = new QListWidgetItem(ui->listSections);
+            ui->listSections->addItem(item);
+
+            Gui::SelectionObject sel(msg);
+            QString text = QString::fromLatin1("%1.%2")
+                    .arg(QString::fromUtf8(sel.getObject()->Label.getValue()))
+                    .arg(QString::fromLatin1(msg.pSubName));
+            item->setText(text);
+
+            QList<QVariant> data;
+            data << QByteArray(msg.pDocName);
+            data << QByteArray(msg.pObjectName);
+            data << QByteArray(msg.pSubName);
+            item->setData(Qt::UserRole, data);
+
+            appendCurve(sel.getObject(), msg.pSubName);
+        }
+        else if (selectionMode == RemoveEdge) {
+            Gui::SelectionObject sel(msg);
+            QList<QVariant> data;
+            data << QByteArray(msg.pDocName);
+            data << QByteArray(msg.pObjectName);
+            data << QByteArray(msg.pSubName);
+
+            // only the three first elements must match
+            for (int i=0; i<ui->listSections->count(); i++) {
+                QListWidgetItem* item = ui->listSections->item(i);
+                QList<QVariant> userdata = item->data(Qt::UserRole).toList();
+                if (userdata.mid(0,3) == data) {
+                    ui->listSections->takeItem(i);
+                    delete item;
+                    break;
+                }
+            }
+
+            removeCurve(sel.getObject(), msg.pSubName);
+        }
+
+        editedObject->recomputeFeature();
+        QTimer::singleShot(50, this, SLOT(clearSelection()));
+    }
+}
+
+void SectionsPanel::onDeleteEdge()
+{
+    int row = ui->listSections->currentRow();
+    QListWidgetItem* item = ui->listSections->takeItem(row);
+    if (item) {
+        checkOpenCommand();
+        QList<QVariant> data;
+        data = item->data(Qt::UserRole).toList();
+        delete item;
+
+        App::Document* doc = App::GetApplication().getDocument(data[0].toByteArray());
+        App::DocumentObject* obj = doc ? doc->getObject(data[1].toByteArray()) : nullptr;
+        std::string sub = data[2].toByteArray().constData();
+
+        removeCurve(obj, sub);
+        editedObject->recomputeFeature();
+    }
+}
+
+void SectionsPanel::onIndexesMoved()
+{
+    QAbstractItemModel* model = qobject_cast<QAbstractItemModel*>(sender());
+    if (!model)
+        return;
+
+    std::vector<App::DocumentObject*> objects;
+    std::vector<std::string> element;
+
+    int rows = model->rowCount();
+    for (int i = 0; i < rows; i++) {
+        QModelIndex index = model->index(i, 0);
+        QList<QVariant> data;
+        data = index.data(Qt::UserRole).toList();
+
+        App::Document* doc = App::GetApplication().getDocument(data[0].toByteArray());
+        App::DocumentObject* obj = doc ? doc->getObject(data[1].toByteArray()) : nullptr;
+        std::string sub = data[2].toByteArray().constData();
+
+        objects.push_back(obj);
+        element.push_back(sub);
+    }
+
+    editedObject->NSections.setValues(objects, element);
+    editedObject->recomputeFeature();
+}
+
+void SectionsPanel::appendCurve(App::DocumentObject* obj, const std::string& subname)
+{
+    auto objects = editedObject->NSections.getValues();
+    objects.push_back(obj);
+    auto element = editedObject->NSections.getSubValues();
+    element.push_back(subname);
+    editedObject->NSections.setValues(objects, element);
+
+    this->vp->highlightReferences(ViewProviderSections::Edge,
+        editedObject->NSections.getSubListValues(), true);
+}
+
+void SectionsPanel::removeCurve(App::DocumentObject* obj, const std::string& subname)
+{
+    this->vp->highlightReferences(ViewProviderSections::Edge,
+        editedObject->NSections.getSubListValues(), false);
+
+    auto objects = editedObject->NSections.getValues();
+    auto element = editedObject->NSections.getSubValues();
+
+    auto it = objects.begin();
+    auto jt = element.begin();
+    for (; it != objects.end() && jt != element.end(); ++it, ++jt) {
+        if (*it == obj && *jt == subname) {
+            objects.erase(it);
+            element.erase(jt);
+            editedObject->NSections.setValues(objects, element);
+            break;
+        }
+    }
+    this->vp->highlightReferences(ViewProviderSections::Edge,
+        editedObject->NSections.getSubListValues(), true);
+
+}
+
+// ----------------------------------------------------------------------------
+
+TaskSections::TaskSections(ViewProviderSections* vp, Surface::Sections* obj)
+{
+    // first task box
+    widget1 = new SectionsPanel(vp, obj);
+    Gui::TaskView::TaskBox* taskbox1 = new Gui::TaskView::TaskBox(
+        Gui::BitmapFactory().pixmap("BezSurf"),
+        widget1->windowTitle(), true, 0);
+    taskbox1->groupLayout()->addWidget(widget1);
+    Content.push_back(taskbox1);
+}
+
+TaskSections::~TaskSections()
+{
+    // automatically deleted in the sub-class
+}
+
+void TaskSections::setEditedObject(Surface::Sections* obj)
+{
+    widget1->setEditedObject(obj);
+}
+
+void TaskSections::open()
+{
+    widget1->open();
+}
+
+bool TaskSections::accept()
+{
+    bool ok = widget1->accept();
+    if (ok) {
+        Gui::Command::commitCommand();
+        Gui::Command::doCommand(Gui::Command::Gui,"Gui.ActiveDocument.resetEdit()");
+        Gui::Command::updateActive();
+    }
+
+    return ok;
+}
+
+bool TaskSections::reject()
+{
+    bool ok = widget1->reject();
+    if (ok) {
+        Gui::Command::abortCommand();
+        Gui::Command::doCommand(Gui::Command::Gui,"Gui.ActiveDocument.resetEdit()");
+        Gui::Command::updateActive();
+    }
+
+    return ok;
+}
+
+}
+
+#include "moc_TaskSections.cpp"

src/Mod/Surface/Gui/TaskSections.h

@@ -0,0 +1,128 @@
+/***************************************************************************
+ *   Copyright (c) 2020 Werner Mayer <wmayer[at]users.sourceforge.net>     *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  is distributed in the hope that it will be useful,      *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef SURFACEGUI_TASKSECTIONS_H
+#define SURFACEGUI_TASKSECTIONS_H
+
+#include <Gui/TaskView/TaskDialog.h>
+#include <Gui/TaskView/TaskView.h>
+#include <Gui/SelectionFilter.h>
+#include <Gui/DocumentObserver.h>
+#include <Base/BoundBox.h>
+#include <Mod/Part/Gui/ViewProviderSpline.h>
+#include <Mod/Surface/App/FeatureSections.h>
+#include <memory>
+
+class QListWidgetItem;
+
+namespace SurfaceGui
+{
+
+class Ui_Sections;
+
+class ViewProviderSections : public PartGui::ViewProviderSpline
+{
+    PROPERTY_HEADER(SurfaceGui::ViewProviderSections);
+    typedef std::vector<App::PropertyLinkSubList::SubSet> References;
+
+public:
+    enum ShapeType {Vertex, Edge, Face};
+    virtual void setupContextMenu(QMenu*, QObject*, const char*);
+    virtual bool setEdit(int ModNum);
+    virtual void unsetEdit(int ModNum);
+    QIcon getIcon(void) const;
+    void highlightReferences(ShapeType type, const References& refs, bool on);
+};
+
+class SectionsPanel : public QWidget,
+                      public Gui::SelectionObserver,
+                      public Gui::DocumentObserver
+{
+    Q_OBJECT
+
+protected:
+    class ShapeSelection;
+    enum SelectionMode { None, AppendEdge, RemoveEdge };
+    SelectionMode selectionMode;
+    Surface::Sections* editedObject;
+    bool checkCommand;
+
+private:
+    std::unique_ptr<Ui_Sections> ui;
+    ViewProviderSections* vp;
+
+public:
+    SectionsPanel(ViewProviderSections* vp, Surface::Sections* obj);
+    ~SectionsPanel();
+
+    void open();
+    void checkOpenCommand();
+    bool accept();
+    bool reject();
+    void setEditedObject(Surface::Sections* obj);
+
+protected:
+    void changeEvent(QEvent *e);
+    virtual void onSelectionChanged(const Gui::SelectionChanges& msg);
+    /** Notifies on undo */
+    virtual void slotUndoDocument(const Gui::Document& Doc);
+    /** Notifies on redo */
+    virtual void slotRedoDocument(const Gui::Document& Doc);
+    /** Notifies when the object is about to be removed. */
+    virtual void slotDeletedObject(const Gui::ViewProviderDocumentObject& Obj);
+
+private Q_SLOTS:
+    void on_buttonEdgeAdd_clicked();
+    void on_buttonEdgeRemove_clicked();
+    void onDeleteEdge(void);
+    void clearSelection();
+    void onIndexesMoved();
+
+private:
+    void appendCurve(App::DocumentObject*, const std::string& subname);
+    void removeCurve(App::DocumentObject*, const std::string& subname);
+};
+
+class TaskSections : public Gui::TaskView::TaskDialog
+{
+    Q_OBJECT
+
+public:
+    TaskSections(ViewProviderSections* vp, Surface::Sections* obj);
+    ~TaskSections();
+    void setEditedObject(Surface::Sections* obj);
+
+public:
+    void open();
+    bool accept();
+    bool reject();
+
+    virtual QDialogButtonBox::StandardButtons getStandardButtons() const
+    { return QDialogButtonBox::Ok | QDialogButtonBox::Cancel; }
+
+private:
+    SectionsPanel* widget1;
+};
+
+} //namespace SurfaceGui
+
+#endif // SURFACEGUI_TASKSECTIONS_H

src/Mod/Surface/Gui/TaskSections.ui

@@ -0,0 +1,83 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>SurfaceGui::Sections</class>
+ <widget class="QWidget" name="SurfaceGui::Sections">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>293</width>
+    <height>443</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>Sections</string>
+  </property>
+  <layout class="QGridLayout" name="gridLayout_2">
+   <item row="0" column="0">
+    <widget class="QGroupBox" name="groupBox">
+     <property name="title">
+      <string>Sections</string>
+     </property>
+     <layout class="QGridLayout" name="gridLayout">
+      <item row="1" column="0" colspan="2">
+       <widget class="QListWidget" name="listSections">
+        <property name="toolTip">
+         <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;List can be reordered by dragging&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+        </property>
+        <property name="dragDropMode">
+         <enum>QAbstractItemView::InternalMove</enum>
+        </property>
+       </widget>
+      </item>
+      <item row="0" column="0" colspan="2">
+       <layout class="QHBoxLayout" name="horizontalLayout_2">
+        <item>
+         <widget class="QToolButton" name="buttonEdgeAdd">
+          <property name="enabled">
+           <bool>true</bool>
+          </property>
+          <property name="sizePolicy">
+           <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+            <horstretch>0</horstretch>
+            <verstretch>0</verstretch>
+           </sizepolicy>
+          </property>
+          <property name="text">
+           <string>Add Edge</string>
+          </property>
+          <property name="checked">
+           <bool>false</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QToolButton" name="buttonEdgeRemove">
+          <property name="sizePolicy">
+           <sizepolicy hsizetype="Expanding" vsizetype="Fixed">
+            <horstretch>0</horstretch>
+            <verstretch>0</verstretch>
+           </sizepolicy>
+          </property>
+          <property name="text">
+           <string>Remove Edge</string>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </item>
+      <item row="2" column="0" colspan="2">
+       <widget class="QLabel" name="statusLabel">
+        <property name="text">
+         <string notr="true">Status messages</string>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>

src/Mod/Surface/Gui/Workbench.cpp

@@ -55,7 +55,8 @@ Gui::MenuItem* Workbench::setupMenuBar() const
     *surface << "Surface_CurveOnMesh"
              << "Surface_ExtendFace"
              << "Surface_Filling"
-             << "Surface_GeomFillSurface";
+             << "Surface_GeomFillSurface"
+             << "Surface_Sections";
 /*    *surface << "Surface_Filling";
     *surface << "Surface_Cut";*/