Run clang-tidy’s modernize-use-nullptr pass.

This replaces all NULL or 0 with nullptr when assigned to or returned as
a pointer.

56 files changed, 213 insertions, 213 deletions

diff --git a/src/live_effects/effect.cpp b/src/live_effects/effect.cpp
index 1e691eb4d..bef7a1e3f 100644
--- a/src/live_effects/effect.cpp
+++ b/src/live_effects/effect.cpp
@@ -181,7 +181,7 @@ Effect::acceptsNumClicks(EffectType type) {
 Effect*
 Effect::New(EffectType lpenr, LivePathEffectObject *lpeobj)
 {
-    Effect* neweffect = NULL;
+    Effect* neweffect = nullptr;
     switch (lpenr) {
         case EMBRODERY_STITCH:
             neweffect = static_cast<Effect*> ( new LPEEmbroderyStitch(lpeobj) );
@@ -353,7 +353,7 @@ Effect::New(EffectType lpenr, LivePathEffectObject *lpeobj)
             break;
         default:
             g_warning("LivePathEffect::Effect::New called with invalid patheffect type (%d)", lpenr);
-            neweffect = NULL;
+            neweffect = nullptr;
             break;
     }
 
@@ -371,7 +371,7 @@ void Effect::createAndApply(const char* name, SPDocument *doc, SPItem *item)
     Inkscape::XML::Node *repr = xml_doc->createElement("inkscape:path-effect");
     repr->setAttribute("effect", name);
 
-    doc->getDefs()->getRepr()->addChild(repr, NULL); // adds to <defs> and assigns the 'id' attribute
+    doc->getDefs()->getRepr()->addChild(repr, nullptr); // adds to <defs> and assigns the 'id' attribute
     const gchar * repr_id = repr->attribute("id");
     Inkscape::GC::release(repr);
 
@@ -396,10 +396,10 @@ Effect::Effect(LivePathEffectObject *lpeobject)
       is_load(true),
       lpeobj(lpeobject),
       concatenate_before_pwd2(false),
-      sp_lpe_item(NULL),
+      sp_lpe_item(nullptr),
       current_zoom(1),
       upd_params(true),
-      current_shape(NULL),
+      current_shape(nullptr),
       provides_own_flash_paths(true), // is automatically set to false if providesOwnFlashPaths() is not overridden
       defaultsopen(false),
       is_ready(false) // is automatically set to false if providesOwnFlashPaths() is not overridden
@@ -480,7 +480,7 @@ Effect::processObjects(LPEAction lpe_action)
         if (id.empty()) {
             return;
         }
-        SPObject *elemref = NULL;
+        SPObject *elemref = nullptr;
         if ((elemref = document->getObjectById(id.c_str()))) {
             Inkscape::XML::Node * elemnode = elemref->getRepr();
             std::vector<SPItem*> item_list;
@@ -498,7 +498,7 @@ Effect::processObjects(LPEAction lpe_action)
                     if (elemnode->attribute("inkscape:path-effect")) {
                         sp_item_list_to_curves(item_list, item_selected, item_to_select);
                     }
-                    elemnode->setAttribute("sodipodi:insensitive", NULL);
+                    elemnode->setAttribute("sodipodi:insensitive", nullptr);
                     SP_ITEM(elemref)->moveTo(SP_ITEM(sp_lpe_item), false);
                 }
                 break;
@@ -513,7 +513,7 @@ Effect::processObjects(LPEAction lpe_action)
                 if (!this->isVisible()/* && std::strcmp(elemref->getId(),sp_lpe_item->getId()) != 0*/) {
                     css->setAttribute("display", "none");
                 } else {
-                    css->setAttribute("display", NULL);
+                    css->setAttribute("display", nullptr);
                 }
                 sp_repr_css_write_string(css,css_str);
                 elemnode->setAttribute("style", css_str.c_str());
@@ -876,7 +876,7 @@ Effect::defaultParamSet()
         vboxwidg->set_margin_top(5);
         return vboxwidg;
     } else {
-        return NULL;
+        return nullptr;
     }
 }
 
@@ -921,7 +921,7 @@ Inkscape::XML::Node *Effect::getRepr()
 
 SPDocument *Effect::getSPDoc()
 {
-    if (lpeobj->document == NULL) {
+    if (lpeobj->document == nullptr) {
         g_message("Effect::getSPDoc() returns NULL");
     }
     return lpeobj->document;
@@ -932,7 +932,7 @@ Effect::getParameter(const char * key)
 {
     Glib::ustring stringkey(key);
 
-    if (param_vector.empty()) return NULL;
+    if (param_vector.empty()) return nullptr;
     std::vector<Parameter *>::iterator it = param_vector.begin();
     while (it != param_vector.end()) {
         Parameter * param = *it;
@@ -943,14 +943,14 @@ Effect::getParameter(const char * key)
         ++it;
     }
 
-    return NULL;
+    return nullptr;
 }
 
 Parameter *
 Effect::getNextOncanvasEditableParam()
 {
     if (param_vector.size() == 0) // no parameters
-        return NULL;
+        return nullptr;
 
     oncanvasedit_it++;
     if (oncanvasedit_it >= static_cast<int>(param_vector.size())) {
@@ -970,7 +970,7 @@ Effect::getNextOncanvasEditableParam()
         }
     } while (oncanvasedit_it != old_it); // iterate until complete loop through map has been made
 
-    return NULL;
+    return nullptr;
 }
 
 void
diff --git a/src/live_effects/lpe-bendpath.cpp b/src/live_effects/lpe-bendpath.cpp
index 7b739256e..69415cf4e 100644
--- a/src/live_effects/lpe-bendpath.cpp
+++ b/src/live_effects/lpe-bendpath.cpp
@@ -46,7 +46,7 @@ class KnotHolderEntityWidthBendPath : public LPEKnotHolderEntity {
         ~KnotHolderEntityWidthBendPath() override
         {
             LPEBendPath *lpe = dynamic_cast<LPEBendPath *> (_effect);
-            lpe->_knot_entity = NULL;
+            lpe->_knot_entity = nullptr;
         }
         void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
         Geom::Point knot_get() const override;
@@ -71,7 +71,7 @@ LPEBendPath::LPEBendPath(LivePathEffectObject *lpeobject) :
     prop_scale.param_set_digits(3);
     prop_scale.param_set_increments(0.01, 0.10);
     
-    _knot_entity = NULL;
+    _knot_entity = nullptr;
     _provides_knotholder_entities = true;
     apply_to_clippath_and_mask = true;
     concatenate_before_pwd2 = true;
@@ -182,7 +182,7 @@ void
 LPEBendPath::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     _knot_entity = new BeP::KnotHolderEntityWidthBendPath(this);
-    _knot_entity->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Change the width"), SP_KNOT_SHAPE_CIRCLE);
+    _knot_entity->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Change the width"), SP_KNOT_SHAPE_CIRCLE);
     knotholder->add(_knot_entity);
     if (hide_knot) {
         _knot_entity->knot->hide();
diff --git a/src/live_effects/lpe-bool.cpp b/src/live_effects/lpe-bool.cpp
index 01b019cec..865968b30 100644
--- a/src/live_effects/lpe-bool.cpp
+++ b/src/live_effects/lpe-bool.cpp
@@ -344,7 +344,7 @@ sp_pathvector_boolop_remove_inner(Geom::PathVector const &pathva, fill_typ fra)
 static fill_typ GetFillTyp(SPItem *item)
 {
     SPCSSAttr *css = sp_repr_css_attr(item->getRepr(), "style");
-    gchar const *val = sp_repr_css_property(css, "fill-rule", NULL);
+    gchar const *val = sp_repr_css_property(css, "fill-rule", nullptr);
     if (val && strcmp(val, "nonzero") == 0) {
         return fill_nonZero;
     } else if (val && strcmp(val, "evenodd") == 0) {
diff --git a/src/live_effects/lpe-bspline.cpp b/src/live_effects/lpe-bspline.cpp
index 7834ff108..04182e84b 100644
--- a/src/live_effects/lpe-bspline.cpp
+++ b/src/live_effects/lpe-bspline.cpp
@@ -208,7 +208,7 @@ void sp_bspline_do_effect(SPCurve *curve, double helper_size)
         Geom::D2<Geom::SBasis> sbasis_in;
         Geom::D2<Geom::SBasis> sbasis_out;
         Geom::D2<Geom::SBasis> sbasis_helper;
-        Geom::CubicBezier const *cubic = NULL;
+        Geom::CubicBezier const *cubic = nullptr;
         curve_n->moveto(curve_it1->initialPoint());
         if (path_it->closed()) {
           const Geom::Curve &closingline = path_it->back_closed(); 
@@ -375,7 +375,7 @@ void LPEBSpline::doBSplineFromWidget(SPCurve *curve, double weight_ammount)
         Geom::Point point_at3(0, 0);
         Geom::D2<Geom::SBasis> sbasis_in;
         Geom::D2<Geom::SBasis> sbasis_out;
-        Geom::CubicBezier const *cubic = NULL;
+        Geom::CubicBezier const *cubic = nullptr;
         curve_n->moveto(curve_it1->initialPoint());
         if (path_it->closed()) {
           const Geom::Curve &closingline = path_it->back_closed(); 
diff --git a/src/live_effects/lpe-clone-original.cpp b/src/live_effects/lpe-clone-original.cpp
index f384c8bec..f491c7ad7 100644
--- a/src/live_effects/lpe-clone-original.cpp
+++ b/src/live_effects/lpe-clone-original.cpp
@@ -46,7 +46,7 @@ LPECloneOriginal::LPECloneOriginal(LivePathEffectObject *lpeobject) :
     const gchar * linkedpath = this->getRepr()->attribute("linkedpath");
     if (linkedpath && strcmp(linkedpath, "") != 0){
         this->getRepr()->setAttribute("linkeditem", linkedpath);
-        this->getRepr()->setAttribute("linkedpath", NULL);
+        this->getRepr()->setAttribute("linkedpath", nullptr);
         this->getRepr()->setAttribute("method", "bsplinespiro");
         this->getRepr()->setAttribute("allow_transforms", "false");
     };
@@ -118,11 +118,11 @@ LPECloneOriginal::cloneAttrbutes(SPObject *origin, SPObject *dest, const gchar *
     }
     gchar ** attarray = g_strsplit(attributes, ",", 0);
     gchar ** iter = attarray;
-    while (*iter != NULL) {
+    while (*iter != nullptr) {
         const char* attribute = (*iter);
         if (strlen(attribute)) {
             if ( shape_dest && shape_origin && (std::strcmp(attribute, "d") == 0)) {
-                SPCurve *c = NULL;
+                SPCurve *c = nullptr;
                 if (method == CLM_BSPLINESPIRO) {
                     c = shape_origin->getCurveForEdit();
                     SPLPEItem * lpe_item = SP_LPE_ITEM(origin);
@@ -157,7 +157,7 @@ LPECloneOriginal::cloneAttrbutes(SPObject *origin, SPObject *dest, const gchar *
                     g_free(str);
                     c->unref();
                 } else {
-                    dest->getRepr()->setAttribute(attribute, NULL);
+                    dest->getRepr()->setAttribute(attribute, nullptr);
                 }
             } else {
                 dest->getRepr()->setAttribute(attribute, origin->getRepr()->attribute(attribute));
@@ -172,12 +172,12 @@ LPECloneOriginal::cloneAttrbutes(SPObject *origin, SPObject *dest, const gchar *
     sp_repr_css_attr_add_from_string(css_dest, dest->getRepr()->attribute("style"));
     gchar ** styleattarray = g_strsplit(style_attributes, ",", 0);
     gchar ** styleiter = styleattarray;
-    while (*styleiter != NULL) {
+    while (*styleiter != nullptr) {
         const char* attribute = (*styleiter);
         if (strlen(attribute)) {
             const char* origin_attribute = sp_repr_css_property(css_origin, attribute, "");
             if (!strlen(origin_attribute)) { //==0
-                sp_repr_css_set_property (css_dest, attribute, NULL);
+                sp_repr_css_set_property (css_dest, attribute, nullptr);
             } else {
                 sp_repr_css_set_property (css_dest, attribute, origin_attribute);
             }
diff --git a/src/live_effects/lpe-copy_rotate.cpp b/src/live_effects/lpe-copy_rotate.cpp
index 650d45747..909bd411e 100644
--- a/src/live_effects/lpe-copy_rotate.cpp
+++ b/src/live_effects/lpe-copy_rotate.cpp
@@ -74,7 +74,7 @@ LPECopyRotate::LPECopyRotate(LivePathEffectObject *lpeobject) :
     _provides_knotholder_entities = true;
     //0.92 compatibility
     if (this->getRepr()->attribute("fuse_paths") && strcmp(this->getRepr()->attribute("fuse_paths"), "true") == 0){
-        this->getRepr()->setAttribute("fuse_paths", NULL);
+        this->getRepr()->setAttribute("fuse_paths", nullptr);
         this->getRepr()->setAttribute("method", "kaleidoskope");
         this->getRepr()->setAttribute("mirror_copies", "true");
     };
@@ -136,7 +136,7 @@ LPECopyRotate::doAfterEffect (SPLPEItem const* lpeitem)
                     if (id.empty()) {
                         return;
                     }
-                    SPObject *elemref = NULL;
+                    SPObject *elemref = nullptr;
                     if (elemref = document->getObjectById(id.c_str())) {
                         SP_ITEM(elemref)->setHidden(true);
                     }
@@ -146,7 +146,7 @@ LPECopyRotate::doAfterEffect (SPLPEItem const* lpeitem)
             }
             previous_num_copies = num_copies;
         }
-        SPObject *elemref = NULL;
+        SPObject *elemref = nullptr;
         guint counter = 0;
         Glib::ustring id = "rotated-0-";
         id += this->lpeobj->getId();
@@ -230,7 +230,7 @@ LPECopyRotate::cloneD(SPObject *orig, SPObject *dest, Geom::Affine transform, bo
             g_free(str);
             c->unref();
         } else {
-            path->getRepr()->setAttribute("d", NULL);
+            path->getRepr()->setAttribute("d", nullptr);
         }
         if (reset) {
             dest->getRepr()->setAttribute("style", shape->getRepr()->attribute("style"));
@@ -242,7 +242,7 @@ Inkscape::XML::Node *
 LPECopyRotate::createPathBase(SPObject *elemref) {
     SPDocument * document = SP_ACTIVE_DOCUMENT;
     if (!document) {
-        return NULL;
+        return nullptr;
     }
     Inkscape::XML::Document *xml_doc = document->getReprDoc();
     Inkscape::XML::Node *prev = elemref->getRepr();
@@ -251,7 +251,7 @@ LPECopyRotate::createPathBase(SPObject *elemref) {
         Inkscape::XML::Node *container = xml_doc->createElement("svg:g");
         container->setAttribute("transform", prev->attribute("transform"));
         std::vector<SPItem*> const item_list = sp_item_group_item_list(group);
-        Inkscape::XML::Node *previous = NULL;
+        Inkscape::XML::Node *previous = nullptr;
         for ( std::vector<SPItem*>::const_iterator iter=item_list.begin();iter!=item_list.end();++iter) {
             SPObject *sub_item = *iter;
             Inkscape::XML::Node *resultnode = createPathBase(sub_item);
@@ -278,8 +278,8 @@ LPECopyRotate::toItem(Geom::Affine transform, size_t i, bool reset)
     elemref_id += "-";
     elemref_id += this->lpeobj->getId();
     items.push_back(elemref_id);
-    SPObject *elemref= NULL;
-    Inkscape::XML::Node *phantom = NULL;
+    SPObject *elemref= nullptr;
+    Inkscape::XML::Node *phantom = nullptr;
     if (elemref = document->getObjectById(elemref_id.c_str())) {
         phantom = elemref->getRepr();
     } else {
diff --git a/src/live_effects/lpe-embrodery-stitch-ordering.cpp b/src/live_effects/lpe-embrodery-stitch-ordering.cpp
index b631065a8..86abf2d68 100644
--- a/src/live_effects/lpe-embrodery-stitch-ordering.cpp
+++ b/src/live_effects/lpe-embrodery-stitch-ordering.cpp
@@ -256,8 +256,8 @@ void OrderingPoint::FindNearest2(const std::vector<OrderingInfoEx *> &infos)
 
     Coord dist0 = infinity();
     Coord dist1 = infinity();
-    nearest[0] = 0;
-    nearest[1] = 0;
+    nearest[0] = nullptr;
+    nearest[1] = nullptr;
 
     for (std::vector<OrderingInfoEx *>::const_iterator it = infos.begin(); it != infos.end(); ++it) {
         Coord dist = distance(point, (*it)->beg.point);
@@ -297,16 +297,16 @@ void OrderingPoint::FindNearest2(const std::vector<OrderingInfoEx *> &infos)
 void OrderingPoint::EnforceMutual(void)
 {
     if (nearest[0] && !(this == nearest[0]->nearest[0] || this == nearest[0]->nearest[1])) {
-        nearest[0] = 0;
+        nearest[0] = nullptr;
     }
 
     if (nearest[1] && !(this == nearest[1]->nearest[0] || this == nearest[1]->nearest[1])) {
-        nearest[1] = 0;
+        nearest[1] = nullptr;
     }
 
     if (nearest[1] && !nearest[0]) {
         nearest[0] = nearest[1];
-        nearest[1] = 0;
+        nearest[1] = nullptr;
     }
 }
 
@@ -318,19 +318,19 @@ void OrderingPoint::EnforceSymmetric(const OrderingPoint &other)
                 (other.nearest[0] && nearest[0]->infoex == other.nearest[0]->infoex) ||
                 (other.nearest[1] && nearest[0]->infoex == other.nearest[1]->infoex)
             )) {
-        nearest[0] = 0;
+        nearest[0] = nullptr;
     }
 
     if (nearest[1] && !(
                 (other.nearest[0] && nearest[1]->infoex == other.nearest[0]->infoex) ||
                 (other.nearest[1] && nearest[1]->infoex == other.nearest[1]->infoex)
             )) {
-        nearest[1] = 0;
+        nearest[1] = nullptr;
     }
 
     if (nearest[1] && !nearest[0]) {
         nearest[0] = nearest[1];
-        nearest[1] = 0;
+        nearest[1] = nullptr;
     }
 }
 
@@ -415,7 +415,7 @@ OrderingGroupNeighbor *OrderingGroupPoint::FindNearestUnused(void)
 
     // it shouldn't happen that we can't find any point at all
     assert(0);
-    return 0;
+    return nullptr;
 }
 
 // Return the other end in the group of the point
@@ -430,11 +430,11 @@ OrderingGroupPoint *OrderingGroupPoint::GetOtherEndGroup(void)
 OrderingGroupPoint *OrderingGroupPoint::GetAltPointGroup(void)
 {
     if (group->nEndPoints < 4) {
-        return 0;
+        return nullptr;
     }
 
     OrderingGroupPoint *alt = group->endpoints[ indexInGroup ^ 2 ];
-    return alt->used ? 0 : alt;
+    return alt->used ? nullptr : alt;
 }
 
 
@@ -635,7 +635,7 @@ bool FindShortestReconnect(std::vector<OrderingSegment> &segments, std::vector<O
 {
     // Find the longest connection outside of the active set
     // The longest segment is then the longest of this longest outside segment and all inside segments
-    OrderingGroupConnection *longestOutside = 0;
+    OrderingGroupConnection *longestOutside = nullptr;
 
     if (contains(connections, *longestConnect)) {
         // The longest connection is inside the active set, so we need to search for the longest outside
@@ -905,7 +905,7 @@ void OrderGroups(std::vector<OrderingGroup *> *groups, const int nDims)
     OrderingGroupPoint *crnt = groups->front()->endpoints[0];
 
     // The longest connection is ignored (we don't want cycles)
-    OrderingGroupConnection *longestConnect = 0;
+    OrderingGroupConnection *longestConnect = nullptr;
 
     for (unsigned int nConnected = 0; nConnected < groups->size(); nConnected++) {
         // Mark both end points of the current segment as used
diff --git a/src/live_effects/lpe-embrodery-stitch-ordering.h b/src/live_effects/lpe-embrodery-stitch-ordering.h
index c307ec555..5f64462f7 100644
--- a/src/live_effects/lpe-embrodery-stitch-ordering.h
+++ b/src/live_effects/lpe-embrodery-stitch-ordering.h
@@ -55,7 +55,7 @@ struct OrderingPoint {
         infoex(infoexIn),
         begin(beginIn)
     {
-        nearest[0] = nearest[1] = 0;
+        nearest[0] = nearest[1] = nullptr;
     }
 
     // Check if both nearest values are valid
@@ -137,7 +137,7 @@ struct OrderingGroupPoint {
         point(pointIn),
         group(groupIn),
         indexInGroup(indexIn),
-        connection(0),
+        connection(nullptr),
         indexInConnection(0),
         begin(beginIn),
         front(frontIn),
@@ -189,8 +189,8 @@ struct OrderingGroupConnection {
     {
         assert(fromIn->connection == 0);
         assert(toIn->connection == 0);
-        points[0] = 0;
-        points[1] = 0;
+        points[0] = nullptr;
+        points[1] = nullptr;
         Connect(0, fromIn);
         Connect(1, toIn);
     }
@@ -227,7 +227,7 @@ struct OrderingGroup {
         index(indexIn)
     {
         for (int i = 0; i < sizeof(endpoints) / sizeof(*endpoints); i++) {
-            endpoints[i] = 0;
+            endpoints[i] = nullptr;
         }
     }
 
diff --git a/src/live_effects/lpe-fill-between-many.cpp b/src/live_effects/lpe-fill-between-many.cpp
index 9715d7ff8..389ddf007 100644
--- a/src/live_effects/lpe-fill-between-many.cpp
+++ b/src/live_effects/lpe-fill-between-many.cpp
@@ -79,7 +79,7 @@ void LPEFillBetweenMany::doOnApply (SPLPEItem const* lpeitem)
                     lpe_repr->setAttribute("applied", "true");
                     lpe_repr->setAttribute("method", "partial");
                     lpe_repr->setAttribute("allow_transforms", "false");
-                    document->getDefs()->getRepr()->addChild(lpe_repr, NULL); // adds to <defs> and assigns the 'id' attribute
+                    document->getDefs()->getRepr()->addChild(lpe_repr, nullptr); // adds to <defs> and assigns the 'id' attribute
                 }
                 std::string lpe_id_href = std::string("#") + lpe_repr->attribute("id");
                 Inkscape::GC::release(lpe_repr);
@@ -149,7 +149,7 @@ void LPEFillBetweenMany::doEffect (SPCurve * curve)
     }
     
     if(!allow_transforms) {
-        SP_ITEM(sp_lpe_item)->setAttribute("transform", NULL);
+        SP_ITEM(sp_lpe_item)->setAttribute("transform", nullptr);
     }
     
     if (!res_pathv.empty() && close) {
diff --git a/src/live_effects/lpe-fill-between-strokes.cpp b/src/live_effects/lpe-fill-between-strokes.cpp
index 5f4fd4fc2..5f327b6a4 100644
--- a/src/live_effects/lpe-fill-between-strokes.cpp
+++ b/src/live_effects/lpe-fill-between-strokes.cpp
@@ -43,7 +43,7 @@ void LPEFillBetweenStrokes::doEffect (SPCurve * curve)
     if (curve) {
         Geom::Affine affine = Geom::identity();
         if(!allow_transforms) {
-            SP_ITEM(sp_lpe_item)->setAttribute("transform", NULL);
+            SP_ITEM(sp_lpe_item)->setAttribute("transform", nullptr);
         }
         if ( linked_path.linksToPath() && second_path.linksToPath() && linked_path.getObject() && second_path.getObject() ) {
             Geom::PathVector linked_pathv = linked_path.get_pathvector();
diff --git a/src/live_effects/lpe-fillet-chamfer.cpp b/src/live_effects/lpe-fillet-chamfer.cpp
index bb60db5c6..a6c8ab90b 100644
--- a/src/live_effects/lpe-fillet-chamfer.cpp
+++ b/src/live_effects/lpe-fillet-chamfer.cpp
@@ -63,7 +63,7 @@ LPEFilletChamfer::LPEFilletChamfer(LivePathEffectObject *lpeobject)
       apply_with_radius(_("Apply changes if radius > 0"), _("Apply changes if radius > 0"), "apply_with_radius", &wr, this, true),
       helper_size(_("Helper path size with direction to node:"),
                   _("Helper path size with direction to node"), "helper_size", &wr, this, 0),
-      _pathvector_satellites(NULL),
+      _pathvector_satellites(nullptr),
       _degenerate_hide(false)
 {
     registerParameter(&satellites_param);
@@ -104,7 +104,7 @@ void LPEFilletChamfer::doOnApply(SPLPEItem const *lpeItem)
         double power = radius;
         if (!flexible) {
             SPDocument * document = SP_ACTIVE_DOCUMENT;
-            SPNamedView *nv = sp_document_namedview(document, NULL);
+            SPNamedView *nv = sp_document_namedview(document, nullptr);
             Glib::ustring display_unit = nv->display_units->abbr;
             power = Inkscape::Util::Quantity::convert(power, unit.get_abbreviation(), display_unit.c_str());
         }
@@ -271,7 +271,7 @@ void LPEFilletChamfer::updateAmount()
     double power = radius;
     if (!flexible) {
         SPDocument * document = SP_ACTIVE_DOCUMENT;
-        SPNamedView *nv = sp_document_namedview(document, NULL);
+        SPNamedView *nv = sp_document_namedview(document, nullptr);
         Glib::ustring display_unit = nv->display_units->abbr;
         power = Inkscape::Util::Quantity::convert(power, unit.get_abbreviation(), display_unit.c_str());
     }
@@ -346,7 +346,7 @@ void LPEFilletChamfer::doBeforeEffect(SPLPEItem const *lpeItem)
                 double power = radius;
                 if (!flexible) {
                     SPDocument * document = SP_ACTIVE_DOCUMENT;
-                    SPNamedView *nv = sp_document_namedview(document, NULL);
+                    SPNamedView *nv = sp_document_namedview(document, nullptr);
                     Glib::ustring display_unit = nv->display_units->abbr;
                     power = Inkscape::Util::Quantity::convert(power, unit.get_abbreviation(), display_unit.c_str());
                 }
diff --git a/src/live_effects/lpe-knot.cpp b/src/live_effects/lpe-knot.cpp
index f42ee75e4..8522444c6 100644
--- a/src/live_effects/lpe-knot.cpp
+++ b/src/live_effects/lpe-knot.cpp
@@ -615,7 +615,7 @@ LPEKnot::addCanvasIndicators(SPLPEItem const */*lpeitem*/, std::vector<Geom::Pat
 void LPEKnot::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     KnotHolderEntity *e = new KnotHolderEntityCrossingSwitcher(this);
-    e->create( NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
+    e->create( nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                _("Drag to select a crossing, click to flip it") );
     knotholder->add(e);
 };
diff --git a/src/live_effects/lpe-lattice2.cpp b/src/live_effects/lpe-lattice2.cpp
index 8c2c3ec31..ae9ec0361 100644
--- a/src/live_effects/lpe-lattice2.cpp
+++ b/src/live_effects/lpe-lattice2.cpp
@@ -238,7 +238,7 @@ LPELattice2::newWidget()
             Parameter * param = *it;
             Gtk::Widget * widg = dynamic_cast<Gtk::Widget *>(param->param_newWidget());
             if(param->param_key == "grid") {
-                widg = NULL;
+                widg = nullptr;
             }
             Glib::ustring * tip = param->param_getTooltip();
             if (widg) {
diff --git a/src/live_effects/lpe-measure-segments.cpp b/src/live_effects/lpe-measure-segments.cpp
index 0ec03ced0..fd016f24c 100644
--- a/src/live_effects/lpe-measure-segments.cpp
+++ b/src/live_effects/lpe-measure-segments.cpp
@@ -182,7 +182,7 @@ LPEMeasureSegments::LPEMeasureSegments(LivePathEffectObject *lpeobject) :
     angle_projection.param_set_range(0.0, 360.0);
     angle_projection.param_set_increments(90.0, 90.0);
     angle_projection.param_set_digits(2);
-    locale_base = strdup(setlocale(LC_NUMERIC, NULL));
+    locale_base = strdup(setlocale(LC_NUMERIC, nullptr));
     previous_size = 0;
     pagenumber = 0;
     general.param_update_default(_("Base of the LPE, focus on measure display and positioning"));
@@ -195,7 +195,7 @@ LPEMeasureSegments::LPEMeasureSegments(LivePathEffectObject *lpeobject) :
 }
 
 LPEMeasureSegments::~LPEMeasureSegments() {
-    doOnRemove(NULL);
+    doOnRemove(nullptr);
 }
 
 Gtk::Widget *
@@ -324,16 +324,16 @@ LPEMeasureSegments::createArrowMarker(Glib::ustring mode)
     style = style + Glib::ustring(";fill-opacity:") + Glib::ustring(os.str());
     style = style + Glib::ustring(";stroke:none");
     Inkscape::XML::Document *xml_doc = document->getReprDoc();
-    SPObject *elemref = NULL;
-    Inkscape::XML::Node *arrow = NULL;
+    SPObject *elemref = nullptr;
+    Inkscape::XML::Node *arrow = nullptr;
     if ((elemref = document->getObjectById(mode.c_str()))) {
         Inkscape::XML::Node *arrow= elemref->getRepr();
         if (arrow) {
             arrow->setAttribute("sodipodi:insensitive", "true");
-            arrow->setAttribute("transform", NULL);
+            arrow->setAttribute("transform", nullptr);
             Inkscape::XML::Node *arrow_data = arrow->firstChild();
             if (arrow_data) {
-                arrow_data->setAttribute("transform", NULL);
+                arrow_data->setAttribute("transform", nullptr);
                 arrow_data->setAttribute("style", style.c_str());
             }
         }
@@ -370,7 +370,7 @@ LPEMeasureSegments::createArrowMarker(Glib::ustring mode)
         Glib::ustring arrowpath = mode + Glib::ustring("_path");
         arrow_path->setAttribute("id", arrowpath.c_str());
         arrow_path->setAttribute("style", style.c_str());
-        arrow->addChild(arrow_path, NULL);
+        arrow->addChild(arrow_path, nullptr);
         Inkscape::GC::release(arrow_path);
         elemref = SP_OBJECT(document->getDefs()->appendChildRepr(arrow));
         Inkscape::GC::release(arrow);
@@ -386,7 +386,7 @@ LPEMeasureSegments::createTextLabel(Geom::Point pos, size_t counter, double leng
         return;
     }
     Inkscape::XML::Document *xml_doc = document->getReprDoc();
-    Inkscape::XML::Node *rtext = NULL;
+    Inkscape::XML::Node *rtext = nullptr;
 
     Glib::ustring lpobjid = this->lpeobj->getId();
     Glib::ustring itemid  = sp_lpe_item->getId();
@@ -394,15 +394,15 @@ LPEMeasureSegments::createTextLabel(Geom::Point pos, size_t counter, double leng
     id += Glib::ustring::format(counter);
     id += "-";
     id += lpobjid;
-    SPObject *elemref = NULL;
-    Inkscape::XML::Node *rtspan = NULL;
+    SPObject *elemref = nullptr;
+    Inkscape::XML::Node *rtspan = nullptr;
     elemref = document->getObjectById(id.c_str());
     if (elemref) {
         rtext = elemref->getRepr();
         sp_repr_set_svg_double(rtext, "x", pos[Geom::X]);
         sp_repr_set_svg_double(rtext, "y", pos[Geom::Y]);
         rtext->setAttribute("sodipodi:insensitive", "true");
-        rtext->setAttribute("transform", NULL);
+        rtext->setAttribute("transform", nullptr);
     } else {
         rtext = xml_doc->createElement("svg:text");
         rtext->setAttribute("xml:space", "preserve");
@@ -445,10 +445,10 @@ LPEMeasureSegments::createTextLabel(Geom::Point pos, size_t counter, double leng
     sp_repr_css_write_string(css,css_str);
     rtext->setAttribute("style", css_str.c_str());
     rtspan->setAttribute("style", css_str.c_str());
-    rtspan->setAttribute("transform", NULL);
+    rtspan->setAttribute("transform", nullptr);
     sp_repr_css_attr_unref (css);
     if (!elemref) {
-        rtext->addChild(rtspan, NULL);
+        rtext->addChild(rtspan, nullptr);
         Inkscape::GC::release(rtspan);
     }
     length = Inkscape::Util::Quantity::convert(length / doc_scale, display_unit.c_str(), unit.get_abbreviation());
@@ -489,10 +489,10 @@ LPEMeasureSegments::createTextLabel(Geom::Point pos, size_t counter, double leng
     if ( !valid ) {
         label_value = Glib::ustring(_("Non Uniform Scale"));
     }
-    Inkscape::XML::Node *rstring = NULL;
+    Inkscape::XML::Node *rstring = nullptr;
     if (!elemref) {
         rstring = xml_doc->createTextNode(label_value.c_str());
-        rtspan->addChild(rstring, NULL);
+        rtspan->addChild(rstring, nullptr);
         Inkscape::GC::release(rstring);
     } else {
         rstring = rtspan->firstChild();
@@ -505,7 +505,7 @@ LPEMeasureSegments::createTextLabel(Geom::Point pos, size_t counter, double leng
     Geom::OptRect bounds = SP_ITEM(elemref)->bounds(SPItem::GEOMETRIC_BBOX);
     if (bounds) {
         anotation_width = bounds->width() * 1.15;
-        rtspan->setAttribute("style", NULL);
+        rtspan->setAttribute("style", nullptr);
     }
     gchar * transform;
     if (rotate_anotation) {
@@ -520,7 +520,7 @@ LPEMeasureSegments::createTextLabel(Geom::Point pos, size_t counter, double leng
         affine *= Geom::Translate(pos);
         transform = sp_svg_transform_write(affine);
     } else {
-        transform = NULL;
+        transform = nullptr;
     }
     rtext->setAttribute("transform", transform);
     g_free(transform);
@@ -541,7 +541,7 @@ LPEMeasureSegments::createLine(Geom::Point start,Geom::Point end, Glib::ustring
     id += lpobjid;
     Inkscape::XML::Document *xml_doc = document->getReprDoc();
     SPObject *elemref = document->getObjectById(id.c_str());
-    Inkscape::XML::Node *line = NULL;
+    Inkscape::XML::Node *line = nullptr;
     if (!main) {
         Geom::Ray ray(start, end);
         Geom::Coord angle = ray.angle();
@@ -575,7 +575,7 @@ LPEMeasureSegments::createLine(Geom::Point start,Geom::Point end, Glib::ustring
         line = elemref->getRepr();
         gchar * line_str = sp_svg_write_path( line_pathv );
         line->setAttribute("d" , line_str);
-        line->setAttribute("transform", NULL);
+        line->setAttribute("transform", nullptr);
         g_free(line_str);
     } else {
         line = xml_doc->createElement("svg:path");
@@ -655,8 +655,8 @@ LPEMeasureSegments::doOnApply(SPLPEItem const* lpeitem)
     SPDocument *document = SP_ACTIVE_DOCUMENT;
     bool saved = DocumentUndo::getUndoSensitive(document);
     DocumentUndo::setUndoSensitive(document, false);
-    Inkscape::XML::Node *styleNode = NULL;
-    Inkscape::XML::Node* textNode = NULL;
+    Inkscape::XML::Node *styleNode = nullptr;
+    Inkscape::XML::Node* textNode = nullptr;
     Inkscape::XML::Node *root = SP_ACTIVE_DOCUMENT->getReprRoot();
     for (unsigned i = 0; i < root->childCount(); ++i) {
         if (Glib::ustring(root->nthChild(i)->name()) == "svg:style") {
@@ -669,7 +669,7 @@ LPEMeasureSegments::doOnApply(SPLPEItem const* lpeitem)
                 }
             }
 
-            if (textNode == NULL) {
+            if (textNode == nullptr) {
                 // Style element found but does not contain text node!
                 std::cerr << "StyleDialog::_getStyleTextNode(): No text node!" << std::endl;
                 textNode = SP_ACTIVE_DOCUMENT->getReprDoc()->createTextNode("");
@@ -679,7 +679,7 @@ LPEMeasureSegments::doOnApply(SPLPEItem const* lpeitem)
         }
     }
 
-    if (styleNode == NULL) {
+    if (styleNode == nullptr) {
         // Style element not found, create one
         styleNode = SP_ACTIVE_DOCUMENT->getReprDoc()->createElement("svg:style");
         textNode  = SP_ACTIVE_DOCUMENT->getReprDoc()->createTextNode("");
@@ -687,7 +687,7 @@ LPEMeasureSegments::doOnApply(SPLPEItem const* lpeitem)
         styleNode->appendChild(textNode);
         Inkscape::GC::release(textNode);
 
-        root->addChild(styleNode, NULL);
+        root->addChild(styleNode, nullptr);
         Inkscape::GC::release(styleNode);
     }
     Glib::ustring styleContent = Glib::ustring(textNode->content());
@@ -919,7 +919,7 @@ LPEMeasureSegments::doBeforeEffect (SPLPEItem const* lpeitem)
     if (shape) {
         //only check constrain viewbox on X
         Geom::Scale scaledoc = document->getDocumentScale();
-        SPNamedView *nv = sp_document_namedview(document, NULL);
+        SPNamedView *nv = sp_document_namedview(document, nullptr);
         display_unit = nv->display_units->abbr;
         if (display_unit.empty()) {
             display_unit = "px";
@@ -938,7 +938,7 @@ LPEMeasureSegments::doBeforeEffect (SPLPEItem const* lpeitem)
         }
         rgb24 = color;
         rgb32 = color32;
-        SPCurve * c = NULL;
+        SPCurve * c = nullptr;
         gchar * fontbutton_str = fontbutton.param_getSVGValue();
         Glib::ustring fontdesc_ustring = Glib::ustring(fontbutton_str);
         Pango::FontDescription fontdesc(fontdesc_ustring);
diff --git a/src/live_effects/lpe-mirror_symmetry.cpp b/src/live_effects/lpe-mirror_symmetry.cpp
index 4d9b218a5..66f00689a 100644
--- a/src/live_effects/lpe-mirror_symmetry.cpp
+++ b/src/live_effects/lpe-mirror_symmetry.cpp
@@ -249,7 +249,7 @@ LPEMirrorSymmetry::doBeforeEffect (SPLPEItem const* lpeitem)
         } else if ( mode == MT_V){
             SPDocument * document = SP_ACTIVE_DOCUMENT;
             if (document) {
-                Geom::Affine transform = i2anc_affine(SP_OBJECT(lpeitem), NULL).inverse();
+                Geom::Affine transform = i2anc_affine(SP_OBJECT(lpeitem), nullptr).inverse();
                 Geom::Point sp = Geom::Point(document->getWidth().value("px")/2.0, 0) * transform;
                 start_point.param_setValue(sp);
                 Geom::Point ep = Geom::Point(document->getWidth().value("px")/2.0, document->getHeight().value("px")) * transform;
@@ -259,7 +259,7 @@ LPEMirrorSymmetry::doBeforeEffect (SPLPEItem const* lpeitem)
         } else { //horizontal page
             SPDocument * document = SP_ACTIVE_DOCUMENT;
             if (document) {
-                Geom::Affine transform = i2anc_affine(SP_OBJECT(lpeitem), NULL).inverse();
+                Geom::Affine transform = i2anc_affine(SP_OBJECT(lpeitem), nullptr).inverse();
                 Geom::Point sp = Geom::Point(0, document->getHeight().value("px")/2.0) * transform;
                 start_point.param_setValue(sp);
                 Geom::Point ep = Geom::Point(document->getWidth().value("px"), document->getHeight().value("px")/2.0) * transform;
@@ -300,7 +300,7 @@ LPEMirrorSymmetry::cloneD(SPObject *orig, SPObject *dest, bool reset)
             g_free(str);
             c->unref();
         } else {
-            dest->getRepr()->setAttribute("d", NULL);
+            dest->getRepr()->setAttribute("d", nullptr);
         }
         if (reset) {
             dest->getRepr()->setAttribute("style", shape->getRepr()->attribute("style"));
@@ -312,7 +312,7 @@ Inkscape::XML::Node *
 LPEMirrorSymmetry::createPathBase(SPObject *elemref) {
     SPDocument * document = SP_ACTIVE_DOCUMENT;
     if (!document) {
-        return NULL;
+        return nullptr;
     }
     Inkscape::XML::Document *xml_doc = document->getReprDoc();
     Inkscape::XML::Node *prev = elemref->getRepr();
@@ -321,7 +321,7 @@ LPEMirrorSymmetry::createPathBase(SPObject *elemref) {
         Inkscape::XML::Node *container = xml_doc->createElement("svg:g");
         container->setAttribute("transform", prev->attribute("transform"));
         std::vector<SPItem*> const item_list = sp_item_group_item_list(group);
-        Inkscape::XML::Node *previous = NULL;
+        Inkscape::XML::Node *previous = nullptr;
         for ( std::vector<SPItem*>::const_iterator iter=item_list.begin();iter!=item_list.end();++iter) {
             SPObject *sub_item = *iter;
             Inkscape::XML::Node *resultnode = createPathBase(sub_item);
@@ -347,8 +347,8 @@ LPEMirrorSymmetry::toMirror(Geom::Affine transform, bool reset)
     elemref_id += this->lpeobj->getId();
     items.clear();
     items.push_back(elemref_id);
-    SPObject *elemref = NULL;
-    Inkscape::XML::Node *phantom = NULL;
+    SPObject *elemref = nullptr;
+    Inkscape::XML::Node *phantom = nullptr;
     if (elemref = document->getObjectById(elemref_id.c_str())) {
         phantom = elemref->getRepr();
     } else {
diff --git a/src/live_effects/lpe-offset.cpp b/src/live_effects/lpe-offset.cpp
index 02b3c8eed..91ea9df74 100644
--- a/src/live_effects/lpe-offset.cpp
+++ b/src/live_effects/lpe-offset.cpp
@@ -90,7 +90,7 @@ LPEOffset::LPEOffset(LivePathEffectObject *lpeobject) :
     offset_pt = Geom::Point();
     origin = Geom::Point();
     evenodd = true;
-    _knot_entity = NULL;
+    _knot_entity = nullptr;
     _provides_knotholder_entities = true;
     apply_to_clippath_and_mask = true;
 }
@@ -204,7 +204,7 @@ LPEOffset::doBeforeEffect (SPLPEItem const* lpeitem)
     SPCSSAttr *css;
     const gchar *val;
     css = sp_repr_css_attr (item->getRepr() , "style");
-    val = sp_repr_css_property (css, "fill-rule", NULL);
+    val = sp_repr_css_property (css, "fill-rule", nullptr);
     bool upd_fill_rule = false;
     if (val && strcmp (val, "nonzero") == 0)
     {
@@ -251,7 +251,7 @@ LPEOffset::doEffect_path(Geom::PathVector const & path_in)
         Geom::Point winding_point = original[0].initialPoint();
         int wind = 0;
         double dist = Geom::infinity();
-        pathv_matrix_point_bbox_wind_distance(original_pathv, Geom::identity(), winding_point, NULL, &wind, &dist, 0.5, NULL);
+        pathv_matrix_point_bbox_wind_distance(original_pathv, Geom::identity(), winding_point, nullptr, &wind, &dist, 0.5, nullptr);
         bool path_inside = wind % 2 != 0;
         Geom::PathVector outline = Inkscape::outline(original, std::abs(offset) * 2 , 
                                (attempt_force_join ? std::numeric_limits<double>::max() : miter_limit),
@@ -382,7 +382,7 @@ LPEOffset::drawHandle(Geom::Point p)
 void LPEOffset::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     _knot_entity = new OfS::KnotHolderEntityOffsetPoint(this);
-    _knot_entity->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Offset point"), SP_KNOT_SHAPE_CIRCLE);
+    _knot_entity->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Offset point"), SP_KNOT_SHAPE_CIRCLE);
     knotholder->add(_knot_entity);
 }
 
diff --git a/src/live_effects/lpe-patternalongpath.cpp b/src/live_effects/lpe-patternalongpath.cpp
index 09794f7a7..dd052c796 100644
--- a/src/live_effects/lpe-patternalongpath.cpp
+++ b/src/live_effects/lpe-patternalongpath.cpp
@@ -53,7 +53,7 @@ namespace WPAP {
         ~KnotHolderEntityWidthPatternAlongPath() override
         {
             LPEPatternAlongPath *lpe = dynamic_cast<LPEPatternAlongPath *> (_effect);
-            lpe->_knot_entity = NULL;
+            lpe->_knot_entity = nullptr;
         }
         void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
         Geom::Point knot_get() const override;
@@ -106,7 +106,7 @@ LPEPatternAlongPath::LPEPatternAlongPath(LivePathEffectObject *lpeobject) :
     registerParameter(&fuse_tolerance);
     prop_scale.param_set_digits(3);
     prop_scale.param_set_increments(0.01, 0.10);
-    _knot_entity = NULL;
+    _knot_entity = nullptr;
     _provides_knotholder_entities = true;
 
 }
@@ -298,7 +298,7 @@ void
 LPEPatternAlongPath::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     _knot_entity = new WPAP::KnotHolderEntityWidthPatternAlongPath(this);
-    _knot_entity->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Change the width"), SP_KNOT_SHAPE_CIRCLE);
+    _knot_entity->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Change the width"), SP_KNOT_SHAPE_CIRCLE);
     knotholder->add(_knot_entity);
     if (hide_knot) {
         _knot_entity->knot->hide();
diff --git a/src/live_effects/lpe-perspective-envelope.cpp b/src/live_effects/lpe-perspective-envelope.cpp
index e95cdfd4b..dcbf3fee7 100644
--- a/src/live_effects/lpe-perspective-envelope.cpp
+++ b/src/live_effects/lpe-perspective-envelope.cpp
@@ -235,7 +235,7 @@ void LPEPerspectiveEnvelope::doEffect(SPCurve *curve)
     }
     Geom::PathVector const original_pathv = pathv_to_linear_and_cubic_beziers(curve->get_pathvector());
     curve->reset();
-    Geom::CubicBezier const *cubic = NULL;
+    Geom::CubicBezier const *cubic = nullptr;
     Geom::Point point_at1(0, 0);
     Geom::Point point_at2(0, 0);
     Geom::Point point_at3(0, 0);
diff --git a/src/live_effects/lpe-perspective_path.cpp b/src/live_effects/lpe-perspective_path.cpp
index 0387e52ba..857bd2952 100644
--- a/src/live_effects/lpe-perspective_path.cpp
+++ b/src/live_effects/lpe-perspective_path.cpp
@@ -73,7 +73,7 @@ void
 LPEPerspectivePath::doOnApply(SPLPEItem const* lpeitem)
 {
     Persp3D *persp = persp3d_document_first_persp(lpeitem->document);
-    if(persp == 0 ){
+    if(persp == nullptr ){
         char *msg = _("You need a BOX 3D object");
         Gtk::MessageDialog dialog(msg, false, Gtk::MESSAGE_INFO,
                                   Gtk::BUTTONS_OK, true);
@@ -88,7 +88,7 @@ LPEPerspectivePath::doBeforeEffect (SPLPEItem const* lpeitem)
     original_bbox(lpeitem, true);
     SPLPEItem * item = const_cast<SPLPEItem*>(lpeitem);
     Persp3D *persp = persp3d_document_first_persp(lpeitem->document);
-    if(persp == 0 ){
+    if(persp == nullptr ){
         char *msg = _("You need a BOX 3D object");
         Gtk::MessageDialog dialog(msg, false, Gtk::MESSAGE_INFO,
                                   Gtk::BUTTONS_OK, true);
@@ -103,10 +103,10 @@ LPEPerspectivePath::doBeforeEffect (SPLPEItem const* lpeitem)
 
 void LPEPerspectivePath::refresh(Gtk::Entry* perspective) {
     perspectiveID = perspective->get_text();
-    Persp3D *first = 0;
-    Persp3D *persp = 0;
+    Persp3D *first = nullptr;
+    Persp3D *persp = nullptr;
     for (auto& child: lpeobj->document->getDefs()->children) {
-        if (SP_IS_PERSP3D(&child) && first == 0) {
+        if (SP_IS_PERSP3D(&child) && first == nullptr) {
             first = SP_PERSP3D(&child);
         }
         if (SP_IS_PERSP3D(&child) && strcmp(child.getId(), const_cast<const gchar *>(perspectiveID.c_str())) == 0) {
@@ -114,14 +114,14 @@ void LPEPerspectivePath::refresh(Gtk::Entry* perspective) {
             break;
         }
     }
-    if(first == 0 ){
+    if(first == nullptr ){
         char *msg = _("You need a BOX 3D object");
         Gtk::MessageDialog dialog(msg, false, Gtk::MESSAGE_INFO,
                                   Gtk::BUTTONS_OK, true);
         dialog.run();
         return;
     }
-    if(persp == 0){
+    if(persp == nullptr){
         persp = first;
         char *msg = _("First perspective selected");
         Gtk::MessageDialog dialog(msg, false, Gtk::MESSAGE_INFO,
@@ -263,7 +263,7 @@ LPEPerspectivePath::newWidget()
 
 void LPEPerspectivePath::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item) {
     KnotHolderEntity *e = new PP::KnotHolderEntityOffset(this);
-    e->create( NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
+    e->create( nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                _("Adjust the origin") );
     knotholder->add(e);
 };
diff --git a/src/live_effects/lpe-powerclip.cpp b/src/live_effects/lpe-powerclip.cpp
index b4c342930..35da3bd26 100644
--- a/src/live_effects/lpe-powerclip.cpp
+++ b/src/live_effects/lpe-powerclip.cpp
@@ -94,7 +94,7 @@ LPEPowerClip::doBeforeEffect (SPLPEItem const* lpeitem){
         std::vector<SPObject*> clip_path_list = clip_path->childList(true);
         for ( std::vector<SPObject*>::const_iterator iter=clip_path_list.begin();iter!=clip_path_list.end();++iter) {
             SPObject * clip_data = *iter;
-            SPObject * clip_to_path = NULL;
+            SPObject * clip_to_path = nullptr;
             if (SP_IS_SHAPE(clip_data) && !SP_IS_PATH(clip_data) && convert_shapes) {
                 SPDocument * document = SP_ACTIVE_DOCUMENT;
                 if (!document) {
@@ -126,7 +126,7 @@ LPEPowerClip::doBeforeEffect (SPLPEItem const* lpeitem){
                 clip_to_path = document->getObjectByRepr(clip_path_node);
 
                 // transform position
-                SPCurve * c = NULL;
+                SPCurve * c = nullptr;
                 c = SP_SHAPE(clip_to_path)->getCurve();
                 if (c) {
                     Geom::PathVector c_pv = c->get_pathvector();
@@ -136,7 +136,7 @@ LPEPowerClip::doBeforeEffect (SPLPEItem const* lpeitem){
                     c->unref();
                 }
                 
-                clip_path_node->setAttribute("transform", NULL);
+                clip_path_node->setAttribute("transform", nullptr);
  
                 if (title && clip_to_path) {
                     clip_to_path->setTitle(title);
@@ -190,7 +190,7 @@ LPEPowerClip::addInverse (SPItem * clip_data){
                 addInverse(subitem);
             }
         } else if (SP_IS_PATH(clip_data)) {
-            SPCurve * c = NULL;
+            SPCurve * c = nullptr;
             c = SP_SHAPE(clip_data)->getCurve();
             if (c) {
                 Geom::PathVector c_pv = c->get_pathvector();
@@ -213,7 +213,7 @@ LPEPowerClip::addInverse (SPItem * clip_data){
                     if (tools_isactive(desktop, TOOLS_NODES)) {
                         Inkscape::Selection * sel = SP_ACTIVE_DESKTOP->getSelection();
                         SPItem * item = sel->singleItem();
-                        if (item != NULL) {
+                        if (item != nullptr) {
                             sel->remove(item);
                             sel->add(item);
                         }
@@ -236,7 +236,7 @@ LPEPowerClip::removeInverse (SPItem * clip_data){
                  removeInverse(subitem);
              }
         } else if (SP_IS_PATH(clip_data)) {
-            SPCurve * c = NULL;
+            SPCurve * c = nullptr;
             c = SP_SHAPE(clip_data)->getCurve();
             if (c) {
                 Geom::PathVector c_pv = c->get_pathvector();
@@ -255,7 +255,7 @@ LPEPowerClip::removeInverse (SPItem * clip_data){
                     if (tools_isactive(desktop, TOOLS_NODES)) {
                         Inkscape::Selection * sel = SP_ACTIVE_DESKTOP->getSelection();
                         SPItem * item = sel->singleItem();
-                        if (item != NULL) {
+                        if (item != nullptr) {
                             sel->remove(item);
                             sel->add(item);
                         }
@@ -413,7 +413,7 @@ LPEPowerClip::flattenClip(SPItem * clip_data, Geom::PathVector &path_in)
              flattenClip(subitem, path_in);
          }
     } else if (SP_IS_PATH(clip_data)) {
-        SPCurve * c = NULL;
+        SPCurve * c = nullptr;
         c = SP_SHAPE(clip_data)->getCurve();
         if (c) {
             Geom::PathVector c_pv = c->get_pathvector();
diff --git a/src/live_effects/lpe-powermask.cpp b/src/live_effects/lpe-powermask.cpp
index 577d8a841..ac3a1dd76 100644
--- a/src/live_effects/lpe-powermask.cpp
+++ b/src/live_effects/lpe-powermask.cpp
@@ -108,7 +108,7 @@ LPEPowerMask::doBeforeEffect (SPLPEItem const* lpeitem){
 void
 LPEPowerMask::setMask(){
     SPMask *mask = SP_ITEM(sp_lpe_item)->mask_ref->getObject();
-    SPObject *elemref = NULL;
+    SPObject *elemref = nullptr;
     SPDocument * document = SP_ACTIVE_DOCUMENT;
     if (!document || !mask) {
         return;
@@ -119,8 +119,8 @@ LPEPowerMask::setMask(){
         return;
     }
     Inkscape::XML::Document *xml_doc = document->getReprDoc();
-    Inkscape::XML::Node *box = NULL;
-    Inkscape::XML::Node *filter = NULL;
+    Inkscape::XML::Node *box = nullptr;
+    Inkscape::XML::Node *filter = nullptr;
     SPDefs * defs = document->getDefs();
     Glib::ustring mask_id = (Glib::ustring)mask->getId();
     Glib::ustring box_id = mask_id + (Glib::ustring)"_box";
@@ -218,12 +218,12 @@ LPEPowerMask::setMask(){
         if(mask_node->attribute("style")) {
             sp_repr_css_attr_add_from_string(css, mask_node->attribute("style"));
         }
-        char const* filter = sp_repr_css_property (css, "filter", NULL);
+        char const* filter = sp_repr_css_property (css, "filter", nullptr);
         if(!filter || !strcmp(filter, filter_uri.c_str())) {
             if (invert && is_visible) {
                 sp_repr_css_set_property (css, "filter", filter_uri.c_str());
             } else {
-                sp_repr_css_set_property (css, "filter", NULL);
+                sp_repr_css_set_property (css, "filter", nullptr);
             }
             Glib::ustring css_str;
             sp_repr_css_write_string(css, css_str);
@@ -250,12 +250,12 @@ LPEPowerMask::setMask(){
         style = style + Glib::ustring(";fill-opacity:") + Glib::ustring(os.str());
         SPCSSAttr *css = sp_repr_css_attr_new();
         sp_repr_css_attr_add_from_string(css, style.c_str());
-        char const* filter = sp_repr_css_property (css, "filter", NULL);
+        char const* filter = sp_repr_css_property (css, "filter", nullptr);
         if(!filter || !strcmp(filter, filter_uri.c_str())) {
             if (invert && is_visible) {
                 sp_repr_css_set_property (css, "filter", filter_uri.c_str());
             } else {
-                sp_repr_css_set_property (css, "filter", NULL);
+                sp_repr_css_set_property (css, "filter", nullptr);
             }
             
         }
@@ -297,7 +297,7 @@ LPEPowerMask::doOnRemove (SPLPEItem const* lpeitem)
             //wrap.param_setValue(false);
             background.param_setValue(false);
             setMask();
-            SPObject *elemref = NULL;
+            SPObject *elemref = nullptr;
             SPDocument * document = SP_ACTIVE_DOCUMENT;
             Glib::ustring mask_id = (Glib::ustring)mask->getId();
             Glib::ustring filter_id = mask_id + (Glib::ustring)"_inverse";
diff --git a/src/live_effects/lpe-powerstroke.cpp b/src/live_effects/lpe-powerstroke.cpp
index 1d64e9042..ce240ab1e 100644
--- a/src/live_effects/lpe-powerstroke.cpp
+++ b/src/live_effects/lpe-powerstroke.cpp
@@ -450,12 +450,12 @@ static Geom::Path path_from_piecewise_fix_cusps( Geom::Piecewise<Geom::D2<Geom::
                         if (arc0) {
                             build_from_sbasis(pb,arc0->toSBasis(), tol, false);
                             delete arc0;
-                            arc0 = NULL;
+                            arc0 = nullptr;
                         }
                         if (arc1) {
                             build_from_sbasis(pb,arc1->toSBasis(), tol, false);
                             delete arc1;
-                            arc1 = NULL;
+                            arc1 = nullptr;
                         }
 
                         break;
diff --git a/src/live_effects/lpe-roughen.cpp b/src/live_effects/lpe-roughen.cpp
index e44688baa..37a94343b 100644
--- a/src/live_effects/lpe-roughen.cpp
+++ b/src/live_effects/lpe-roughen.cpp
@@ -222,7 +222,7 @@ void LPERoughen::doEffect(SPCurve *curve)
           }
         }
         while (curve_it1 != curve_endit) {
-            Geom::CubicBezier const *cubic = NULL;
+            Geom::CubicBezier const *cubic = nullptr;
             cubic = dynamic_cast<Geom::CubicBezier const *>(&*curve_it1);
             if (cubic) {
                 nCurve->curveto((*cubic)[1] + last_move, (*cubic)[2], curve_it1->finalPoint());
diff --git a/src/live_effects/lpe-ruler.cpp b/src/live_effects/lpe-ruler.cpp
index 7726af176..0cda15b81 100644
--- a/src/live_effects/lpe-ruler.cpp
+++ b/src/live_effects/lpe-ruler.cpp
@@ -79,7 +79,7 @@ LPERuler::ruler_mark(Geom::Point const &A, Geom::Point const &n, MarkType const
 
     double real_mark_length = mark_length;
     SPDocument * document = SP_ACTIVE_DOCUMENT;
-    SPNamedView *nv = sp_document_namedview(document, NULL);
+    SPNamedView *nv = sp_document_namedview(document, nullptr);
     Glib::ustring display_unit = nv->display_units->abbr;
     real_mark_length = Inkscape::Util::Quantity::convert(real_mark_length, unit.get_abbreviation(), display_unit.c_str());
     double real_minor_mark_length = minor_mark_length;
@@ -134,7 +134,7 @@ LPERuler::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_i
 
     double real_mark_distance = mark_distance;
     SPDocument * document = SP_ACTIVE_DOCUMENT;
-    SPNamedView *nv = sp_document_namedview(document, NULL);
+    SPNamedView *nv = sp_document_namedview(document, nullptr);
     Glib::ustring display_unit = nv->display_units->abbr;
     real_mark_distance = Inkscape::Util::Quantity::convert(real_mark_distance, unit.get_abbreviation(), display_unit.c_str());
 
diff --git a/src/live_effects/lpe-show_handles.cpp b/src/live_effects/lpe-show_handles.cpp
index 35da722d0..aa4b363f9 100644
--- a/src/live_effects/lpe-show_handles.cpp
+++ b/src/live_effects/lpe-show_handles.cpp
@@ -124,7 +124,7 @@ LPEShowHandles::generateHelperPath(Geom::PathVector result)
         return;
     }
 
-    Geom::CubicBezier const *cubic = NULL;
+    Geom::CubicBezier const *cubic = nullptr;
     for (Geom::PathVector::iterator path_it = result.begin(); path_it != result.end(); ++path_it) {
         //Si está vacío...
         if (path_it->empty()) {
diff --git a/src/live_effects/lpe-simplify.cpp b/src/live_effects/lpe-simplify.cpp
index e676f37a0..e640475dc 100644
--- a/src/live_effects/lpe-simplify.cpp
+++ b/src/live_effects/lpe-simplify.cpp
@@ -153,7 +153,7 @@ LPESimplify::generateHelperPathAndSmooth(Geom::PathVector &result)
         return;
     }
     Geom::PathVector tmp_path;
-    Geom::CubicBezier const *cubic = NULL;
+    Geom::CubicBezier const *cubic = nullptr;
     for (Geom::PathVector::iterator path_it = result.begin(); path_it != result.end(); ++path_it) {
         if (path_it->empty()) {
             continue;
diff --git a/src/live_effects/lpe-tangent_to_curve.cpp b/src/live_effects/lpe-tangent_to_curve.cpp
index ee2e6552b..6c34fc9e6 100644
--- a/src/live_effects/lpe-tangent_to_curve.cpp
+++ b/src/live_effects/lpe-tangent_to_curve.cpp
@@ -97,19 +97,19 @@ void
 LPETangentToCurve::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item) {
     {
         KnotHolderEntity *e = new TtC::KnotHolderEntityAttachPt(this);
-        e->create( NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
+        e->create( nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                    _("Adjust the point of attachment of the tangent") );
         knotholder->add(e);
     }
     {
         KnotHolderEntity *e = new TtC::KnotHolderEntityLeftEnd(this);
-        e->create( NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
+        e->create( nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                     _("Adjust the <b>left</b> end of the tangent") );
         knotholder->add(e);
     }
     {
         KnotHolderEntity *e = new TtC::KnotHolderEntityRightEnd(this);
-        e->create( NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
+        e->create( nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                    _("Adjust the <b>right</b> end of the tangent") );
         knotholder->add(e);
     }
diff --git a/src/live_effects/lpe-taperstroke.cpp b/src/live_effects/lpe-taperstroke.cpp
index 212485ecf..63225d745 100644
--- a/src/live_effects/lpe-taperstroke.cpp
+++ b/src/live_effects/lpe-taperstroke.cpp
@@ -450,11 +450,11 @@ Piecewise<D2<SBasis> > stretch_along(Piecewise<D2<SBasis> > pwd2_in, Geom::Path
 void LPETaperStroke::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     KnotHolderEntity *e = new TpS::KnotHolderEntityAttachBegin(this);
-    e->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Start point of the taper"), SP_KNOT_SHAPE_CIRCLE);
+    e->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Start point of the taper"), SP_KNOT_SHAPE_CIRCLE);
     knotholder->add(e);
 
     KnotHolderEntity *f = new TpS::KnotHolderEntityAttachEnd(this);
-    f->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("End point of the taper"), SP_KNOT_SHAPE_CIRCLE);
+    f->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("End point of the taper"), SP_KNOT_SHAPE_CIRCLE);
     knotholder->add(f);
 }
 
diff --git a/src/live_effects/lpeobject-reference.cpp b/src/live_effects/lpeobject-reference.cpp
index edede5ca1..14472d001 100644
--- a/src/live_effects/lpeobject-reference.cpp
+++ b/src/live_effects/lpeobject-reference.cpp
@@ -25,12 +25,12 @@ static void lpeobjectreference_source_modified(SPObject *iSource, guint flags, L
 LPEObjectReference::LPEObjectReference(SPObject* i_owner) : URIReference(i_owner)
 {
     owner=i_owner;
-    lpeobject_href = NULL;
-    lpeobject_repr = NULL;
-    lpeobject = NULL;
+    lpeobject_href = nullptr;
+    lpeobject_repr = nullptr;
+    lpeobject = nullptr;
     _changed_connection = changedSignal().connect(sigc::bind(sigc::ptr_fun(lpeobjectreference_href_changed), this)); // listening to myself, this should be virtual instead
 
-    user_unlink = NULL;
+    user_unlink = nullptr;
 }
 
 LPEObjectReference::~LPEObjectReference(void)
@@ -80,7 +80,7 @@ LPEObjectReference::unlink(void)
 {
     if (lpeobject_href) {
         g_free(lpeobject_href);
-        lpeobject_href = NULL;
+        lpeobject_href = nullptr;
     }
     detach();
 }
@@ -88,7 +88,7 @@ LPEObjectReference::unlink(void)
 void
 LPEObjectReference::start_listening(LivePathEffectObject* to)
 {
-    if ( to == NULL ) {
+    if ( to == nullptr ) {
         return;
     }
     lpeobject = to;
@@ -102,8 +102,8 @@ LPEObjectReference::quit_listening(void)
 {
     _modified_connection.disconnect();
     _delete_connection.disconnect();
-    lpeobject_repr = NULL;
-    lpeobject = NULL;
+    lpeobject_repr = nullptr;
+    lpeobject = nullptr;
 }
 
 static void
diff --git a/src/live_effects/lpeobject.cpp b/src/live_effects/lpeobject.cpp
index bc5ff0576..c05d00d60 100644
--- a/src/live_effects/lpeobject.cpp
+++ b/src/live_effects/lpeobject.cpp
@@ -22,17 +22,17 @@
 static void livepatheffect_on_repr_attr_changed (Inkscape::XML::Node * repr, const gchar *key, const gchar *oldval, const gchar *newval, bool is_interactive, void * data);
 
 static Inkscape::XML::NodeEventVector const livepatheffect_repr_events = {
-    NULL, /* child_added */
-    NULL, /* child_removed */
+    nullptr, /* child_added */
+    nullptr, /* child_removed */
     livepatheffect_on_repr_attr_changed,
-    NULL, /* content_changed */
-    NULL  /* order_changed */
+    nullptr, /* content_changed */
+    nullptr  /* order_changed */
 };
 
 
 LivePathEffectObject::LivePathEffectObject()
     : SPObject(), effecttype(Inkscape::LivePathEffect::INVALID_LPE), effecttype_set(false),
-      lpe(NULL)
+      lpe(nullptr)
 {
 #ifdef LIVEPATHEFFECT_VERBOSE
     g_message("Init livepatheffectobject");
@@ -46,7 +46,7 @@ LivePathEffectObject::~LivePathEffectObject() {
  * Virtual build: set livepatheffect attributes from its associated XML node.
  */
 void LivePathEffectObject::build(SPDocument *document, Inkscape::XML::Node *repr) {
-    g_assert(this != NULL);
+    g_assert(this != nullptr);
     g_assert(SP_IS_OBJECT(this));
 
     SPObject::build(document, repr);
@@ -85,7 +85,7 @@ void LivePathEffectObject::release() {
 
     if (this->lpe) {
         delete this->lpe;
-        this->lpe = NULL;
+        this->lpe = nullptr;
     }
 
     this->effecttype = Inkscape::LivePathEffect::INVALID_LPE;
@@ -105,7 +105,7 @@ void LivePathEffectObject::set(unsigned key, gchar const *value) {
         case SP_PROP_PATH_EFFECT:
             if (this->lpe) {
                 delete this->lpe;
-                this->lpe = NULL;
+                this->lpe = nullptr;
             }
 
             if ( value && Inkscape::LivePathEffect::LPETypeConverter.is_valid_key(value) ) {
@@ -114,7 +114,7 @@ void LivePathEffectObject::set(unsigned key, gchar const *value) {
                 this->effecttype_set = true;
             } else {
                 this->effecttype = Inkscape::LivePathEffect::INVALID_LPE;
-                this->lpe = NULL;
+                this->lpe = nullptr;
                 this->effecttype_set = false;
             }
 
@@ -180,7 +180,7 @@ LivePathEffectObject *LivePathEffectObject::fork_private_if_necessary(unsigned i
         Inkscape::XML::Document *xml_doc = doc->getReprDoc();
         Inkscape::XML::Node *dup_repr = this->getRepr()->duplicate(xml_doc);
 
-        doc->getDefs()->getRepr()->addChild(dup_repr, NULL);
+        doc->getDefs()->getRepr()->addChild(dup_repr, nullptr);
         LivePathEffectObject *lpeobj_new = LIVEPATHEFFECT( doc->getObjectByRepr(dup_repr) );
 
         Inkscape::GC::release(dup_repr);
diff --git a/src/live_effects/parameter/array.cpp b/src/live_effects/parameter/array.cpp
index 7470f54cd..3c1498fc3 100644
--- a/src/live_effects/parameter/array.cpp
+++ b/src/live_effects/parameter/array.cpp
@@ -57,7 +57,7 @@ ArrayParam<std::vector<Satellite > >::readsvg(const gchar * str)
     }
     gchar ** strarray = g_strsplit(str, "@", 0);
     gchar ** iter = strarray;
-    while (*iter != NULL) {
+    while (*iter != nullptr) {
         gchar ** strsubarray = g_strsplit(*iter, ",", 8);
         if (*strsubarray[7]) {//steps always > 0
             Satellite *satellite = new Satellite();
diff --git a/src/live_effects/parameter/array.h b/src/live_effects/parameter/array.h
index be19889b3..156de2f81 100644
--- a/src/live_effects/parameter/array.h
+++ b/src/live_effects/parameter/array.h
@@ -46,14 +46,14 @@ public:
     }
 
     Gtk::Widget * param_newWidget() override {
-        return NULL;
+        return nullptr;
     }
 
     bool param_readSVGValue(const gchar * strvalue) override {
         _vector.clear();
         gchar ** strarray = g_strsplit(strvalue, "|", 0);
         gchar ** iter = strarray;
-        while (*iter != NULL) {
+        while (*iter != nullptr) {
             _vector.push_back( readsvg(*iter) );
             iter++;
         }
diff --git a/src/live_effects/parameter/bool.cpp b/src/live_effects/parameter/bool.cpp
index bfbda2bfd..2e8c4dbcc 100644
--- a/src/live_effects/parameter/bool.cpp
+++ b/src/live_effects/parameter/bool.cpp
@@ -84,7 +84,7 @@ BoolParam::param_newWidget()
         checkwdg->set_undo_parameters(SP_VERB_DIALOG_LIVE_PATH_EFFECT, _("Change bool parameter"));
         return dynamic_cast<Gtk::Widget *> (checkwdg);
     } else {
-        return NULL;
+        return nullptr;
     }
 }
 
diff --git a/src/live_effects/parameter/colorpicker.cpp b/src/live_effects/parameter/colorpicker.cpp
index d4ebdaa1c..ec2b18389 100644
--- a/src/live_effects/parameter/colorpicker.cpp
+++ b/src/live_effects/parameter/colorpicker.cpp
@@ -43,7 +43,7 @@ ColorPickerParam::param_set_default()
 static guint32 sp_read_color_alpha(gchar const *str, guint32 def)
 {
     guint32 val = 0;
-    if (str == NULL) return def;
+    if (str == nullptr) return def;
     while ((*str <= ' ') && *str) str++;
     if (!*str) return def;
 
diff --git a/src/live_effects/parameter/hidden.cpp b/src/live_effects/parameter/hidden.cpp
index 5a21f572b..fd062d277 100644
--- a/src/live_effects/parameter/hidden.cpp
+++ b/src/live_effects/parameter/hidden.cpp
@@ -69,7 +69,7 @@ HiddenParam::param_getDefaultSVGValue() const
 Gtk::Widget *
 HiddenParam::param_newWidget()
 {
-    return NULL;
+    return nullptr;
 }
 
 void
diff --git a/src/live_effects/parameter/item.cpp b/src/live_effects/parameter/item.cpp
index 2107a5912..c22a3df33 100644
--- a/src/live_effects/parameter/item.cpp
+++ b/src/live_effects/parameter/item.cpp
@@ -40,7 +40,7 @@ ItemParam::ItemParam( const Glib::ustring& label, const Glib::ustring& tip,
                       Effect* effect, const gchar * default_value)
     : Parameter(label, tip, key, wr, effect),
       changed(true),
-      href(NULL),
+      href(nullptr),
       ref( (SPObject*)effect->getLPEObj() )
 {
     last_transform = Geom::identity();
@@ -154,7 +154,7 @@ ItemParam::addCanvasIndicators(SPLPEItem const*/*lpeitem*/, std::vector<Geom::Pa
 void
 ItemParam::start_listening(SPObject * to)
 {
-    if ( to == NULL ) {
+    if ( to == nullptr ) {
         return;
     }
     linked_delete_connection = to->connectDelete(sigc::mem_fun(*this, &ItemParam::linked_delete));
@@ -188,7 +188,7 @@ ItemParam::remove_link()
     if (href) {
         ref.detach();
         g_free(href);
-        href = NULL;
+        href = nullptr;
     }
 }
 
diff --git a/src/live_effects/parameter/message.cpp b/src/live_effects/parameter/message.cpp
index 03eb2219f..a6e919558 100644
--- a/src/live_effects/parameter/message.cpp
+++ b/src/live_effects/parameter/message.cpp
@@ -20,7 +20,7 @@ MessageParam::MessageParam( const Glib::ustring& label, const Glib::ustring& tip
       message(default_message),
       defmessage(default_message)
 {
-    _label  = NULL;
+    _label  = nullptr;
     _min_height = -1;
 }
 
diff --git a/src/live_effects/parameter/originalitem.cpp b/src/live_effects/parameter/originalitem.cpp
index 52e4c2fd8..820c4d6b9 100644
--- a/src/live_effects/parameter/originalitem.cpp
+++ b/src/live_effects/parameter/originalitem.cpp
@@ -105,7 +105,7 @@ OriginalItemParam::on_select_original_button_click()
 {
     SPDesktop *desktop = SP_ACTIVE_DESKTOP;
     SPItem *original = ref.getObject();
-    if (desktop == NULL || original == NULL) {
+    if (desktop == nullptr || original == nullptr) {
         return;
     }
     Inkscape::Selection *selection = desktop->getSelection();
diff --git a/src/live_effects/parameter/originalitem.h b/src/live_effects/parameter/originalitem.h
index 4b285f8e1..d070161ac 100644
--- a/src/live_effects/parameter/originalitem.h
+++ b/src/live_effects/parameter/originalitem.h
@@ -23,7 +23,7 @@ public:
                 Inkscape::UI::Widget::Registry* wr,
                 Effect* effect);
     ~OriginalItemParam() override;
-    bool linksToItem() const { return (href != NULL); }
+    bool linksToItem() const { return (href != nullptr); }
     SPItem * getObject() const { return ref.getObject(); }
 
     Gtk::Widget * param_newWidget() override;
diff --git a/src/live_effects/parameter/originalitemarray.cpp b/src/live_effects/parameter/originalitemarray.cpp
index 5a0d67d26..3116b1f9c 100644
--- a/src/live_effects/parameter/originalitemarray.cpp
+++ b/src/live_effects/parameter/originalitemarray.cpp
@@ -323,7 +323,7 @@ void OriginalItemArrayParam::unlink(ItemAndActive* to)
     to->ref.detach();
     if (to->href) {
         g_free(to->href);
-        to->href = NULL;
+        to->href = nullptr;
     }    
 }
 
@@ -398,12 +398,12 @@ bool OriginalItemArrayParam::param_readSVGValue(const gchar* strvalue)
         _store->clear();
 
         gchar ** strarray = g_strsplit(strvalue, "|", 0);
-        for (gchar ** iter = strarray; *iter != NULL; iter++) {
+        for (gchar ** iter = strarray; *iter != nullptr; iter++) {
             if ((*iter)[0] == '#') {
                 gchar ** substrarray = g_strsplit(*iter, ",", 0);
                 ItemAndActive* w = new ItemAndActive((SPObject *)param_effect->getLPEObj());
                 w->href = g_strdup(*substrarray);
-                w->actived = *(substrarray+1) != NULL && (*(substrarray+1))[0] == '1';
+                w->actived = *(substrarray+1) != nullptr && (*(substrarray+1))[0] == '1';
                 w->linked_changed_connection = w->ref.changedSignal().connect(sigc::bind<ItemAndActive *>(sigc::mem_fun(*this, &OriginalItemArrayParam::linked_changed), w));
                 w->ref.attach(URI(w->href));
 
diff --git a/src/live_effects/parameter/originalitemarray.h b/src/live_effects/parameter/originalitemarray.h
index edb5a3be5..968aeaff0 100644
--- a/src/live_effects/parameter/originalitemarray.h
+++ b/src/live_effects/parameter/originalitemarray.h
@@ -32,7 +32,7 @@ namespace LivePathEffect {
 class ItemAndActive {
 public:
     ItemAndActive(SPObject *owner)
-    : href(NULL),
+    : href(nullptr),
     ref(owner),
     actived(true)
     {
diff --git a/src/live_effects/parameter/originalpath.cpp b/src/live_effects/parameter/originalpath.cpp
index 018e1e69e..5ad5546da 100644
--- a/src/live_effects/parameter/originalpath.cpp
+++ b/src/live_effects/parameter/originalpath.cpp
@@ -90,7 +90,7 @@ OriginalPathParam::param_newWidget()
 void
 OriginalPathParam::linked_modified_callback(SPObject *linked_obj, guint /*flags*/)
 {
-    SPCurve *curve = NULL;
+    SPCurve *curve = nullptr;
     if (SP_IS_SHAPE(linked_obj)) {
         if (_from_original_d) {
             curve = SP_SHAPE(linked_obj)->getCurveForEdit();
@@ -102,7 +102,7 @@ OriginalPathParam::linked_modified_callback(SPObject *linked_obj, guint /*flags*
         curve = SP_TEXT(linked_obj)->getNormalizedBpath();
     }
 
-    if (curve == NULL) {
+    if (curve == nullptr) {
         // curve invalid, set empty pathvector
         _pathvector = Geom::PathVector();
     } else {
@@ -128,7 +128,7 @@ OriginalPathParam::on_select_original_button_click()
 {
     SPDesktop *desktop = SP_ACTIVE_DESKTOP;
     SPItem *original = ref.getObject();
-    if (desktop == NULL || original == NULL) {
+    if (desktop == nullptr || original == nullptr) {
         return;
     }
     Inkscape::Selection *selection = desktop->getSelection();
diff --git a/src/live_effects/parameter/originalpath.h b/src/live_effects/parameter/originalpath.h
index bd7b10741..4432d063d 100644
--- a/src/live_effects/parameter/originalpath.h
+++ b/src/live_effects/parameter/originalpath.h
@@ -24,7 +24,7 @@ public:
                 Effect* effect);
     ~OriginalPathParam() override;
 
-    bool linksToPath() const { return (href != NULL); }
+    bool linksToPath() const { return (href != nullptr); }
     SPItem * getObject() const { return ref.getObject(); }
 
     Gtk::Widget * param_newWidget() override;
diff --git a/src/live_effects/parameter/originalpatharray.cpp b/src/live_effects/parameter/originalpatharray.cpp
index 2091c4d71..f9e56c8f3 100644
--- a/src/live_effects/parameter/originalpatharray.cpp
+++ b/src/live_effects/parameter/originalpatharray.cpp
@@ -363,7 +363,7 @@ void OriginalPathArrayParam::unlink(PathAndDirectionAndVisible* to)
     to->_pathvector = Geom::PathVector();
     if (to->href) {
         g_free(to->href);
-        to->href = NULL;
+        to->href = nullptr;
     }
 }
 
@@ -424,7 +424,7 @@ void OriginalPathArrayParam::setPathVector(SPObject *linked_obj, guint /*flags*/
     if (!to) {
         return;
     }
-    SPCurve *curve = NULL;
+    SPCurve *curve = nullptr;
     if (SP_IS_SHAPE(linked_obj)) {
         SPLPEItem * lpe_item = SP_LPE_ITEM(linked_obj);
         if (_from_original_d) {
@@ -451,7 +451,7 @@ void OriginalPathArrayParam::setPathVector(SPObject *linked_obj, guint /*flags*/
         curve = SP_TEXT(linked_obj)->getNormalizedBpath();
     }
 
-    if (curve == NULL) {
+    if (curve == nullptr) {
         // curve invalid, set empty pathvector
         to->_pathvector = Geom::PathVector();
     } else {
@@ -483,14 +483,14 @@ bool OriginalPathArrayParam::param_readSVGValue(const gchar* strvalue)
         _store->clear();
 
         gchar ** strarray = g_strsplit(strvalue, "|", 0);
-        for (gchar ** iter = strarray; *iter != NULL; iter++) {
+        for (gchar ** iter = strarray; *iter != nullptr; iter++) {
             if ((*iter)[0] == '#') {
                 gchar ** substrarray = g_strsplit(*iter, ",", 0);
                 PathAndDirectionAndVisible* w = new PathAndDirectionAndVisible((SPObject *)param_effect->getLPEObj());
                 w->href = g_strdup(*substrarray);
-                w->reversed = *(substrarray+1) != NULL && (*(substrarray+1))[0] == '1';
+                w->reversed = *(substrarray+1) != nullptr && (*(substrarray+1))[0] == '1';
                 //Like this to make backwards compatible, new value added in 0.93
-                w->visibled = *(substrarray+2) == NULL || (*(substrarray+2))[0] == '1';
+                w->visibled = *(substrarray+2) == nullptr || (*(substrarray+2))[0] == '1';
                 w->linked_changed_connection = w->ref.changedSignal().connect(sigc::bind<PathAndDirectionAndVisible *>(sigc::mem_fun(*this, &OriginalPathArrayParam::linked_changed), w));
                 w->ref.attach(URI(w->href));
 
diff --git a/src/live_effects/parameter/originalpatharray.h b/src/live_effects/parameter/originalpatharray.h
index 92edff103..23a41215f 100644
--- a/src/live_effects/parameter/originalpatharray.h
+++ b/src/live_effects/parameter/originalpatharray.h
@@ -32,7 +32,7 @@ namespace LivePathEffect {
 class PathAndDirectionAndVisible {
 public:
     PathAndDirectionAndVisible(SPObject *owner)
-    : href(NULL),
+    : href(nullptr),
     ref(owner),
     _pathvector(Geom::PathVector()),
     reversed(false),
diff --git a/src/live_effects/parameter/parameter.cpp b/src/live_effects/parameter/parameter.cpp
index a175359f0..acfe159ab 100644
--- a/src/live_effects/parameter/parameter.cpp
+++ b/src/live_effects/parameter/parameter.cpp
@@ -196,7 +196,7 @@ ScalarParam::param_newWidget()
         }
         return dynamic_cast<Gtk::Widget *> (rsu);
     } else {
-        return NULL;
+        return nullptr;
     }
 }
 
diff --git a/src/live_effects/parameter/path.cpp b/src/live_effects/parameter/path.cpp
index ab385daa6..649d3a1ef 100644
--- a/src/live_effects/parameter/path.cpp
+++ b/src/live_effects/parameter/path.cpp
@@ -64,7 +64,7 @@ PathParam::PathParam( const Glib::ustring& label, const Glib::ustring& tip,
       _pathvector(),
       _pwd2(),
       must_recalculate_pwd2(false),
-      href(NULL),
+      href(nullptr),
       ref( (SPObject*)effect->getLPEObj() )
 {
     defvalue = g_strdup(default_value);
@@ -198,8 +198,8 @@ PathParam::param_newWidget()
     Gtk::Label* pLabel = Gtk::manage(new Gtk::Label(param_label));
     static_cast<Gtk::HBox*>(_widget)->pack_start(*pLabel, true, true);
     pLabel->set_tooltip_text(param_tooltip);
-    Gtk::Image * pIcon = NULL;
-    Gtk::Button * pButton = NULL;
+    Gtk::Image * pIcon = nullptr;
+    Gtk::Button * pButton = nullptr;
     if (_edit_button) {
         pIcon = Gtk::manage(new Gtk::Image());
         pIcon->set_from_icon_name( INKSCAPE_ICON("tool-node-editor"), Gtk::ICON_SIZE_BUTTON);
@@ -398,7 +398,7 @@ PathParam::emit_changed()
 void
 PathParam::start_listening(SPObject * to)
 {
-    if ( to == NULL ) {
+    if ( to == nullptr ) {
         return;
     }
     linked_delete_connection = to->connectDelete(sigc::mem_fun(*this, &PathParam::linked_delete));
@@ -432,7 +432,7 @@ PathParam::remove_link()
     if (href) {
         ref.detach();
         g_free(href);
-        href = NULL;
+        href = nullptr;
     }
 }
 
@@ -457,7 +457,7 @@ void PathParam::linked_transformed(Geom::Affine const *rel_transf, SPItem *moved
 void
 PathParam::linked_modified_callback(SPObject *linked_obj, guint /*flags*/)
 {
-    SPCurve *curve = NULL;
+    SPCurve *curve = nullptr;
     if (SP_IS_SHAPE(linked_obj)) {
         if (_from_original_d) {
             curve = SP_SHAPE(linked_obj)->getCurveForEdit();
@@ -469,7 +469,7 @@ PathParam::linked_modified_callback(SPObject *linked_obj, guint /*flags*/)
         curve = SP_TEXT(linked_obj)->getNormalizedBpath();
     }
 
-    if (curve == NULL) {
+    if (curve == nullptr) {
         // curve invalid, set default value
         _pathvector = sp_svg_read_pathv(defvalue);
     } else {
@@ -492,7 +492,7 @@ void
 PathParam::on_edit_button_click()
 {
     SPItem * item = SP_ACTIVE_DESKTOP->getSelection()->singleItem();
-    if (item != NULL) {
+    if (item != nullptr) {
         param_editOncanvas(item, SP_ACTIVE_DESKTOP);
     }
 }
@@ -505,7 +505,7 @@ PathParam::paste_param_path(const char *svgd)
         // remove possible link to path
         remove_link();
         SPItem * item = SP_ACTIVE_DESKTOP->getSelection()->singleItem();
-        if (item != NULL) {
+        if (item != nullptr) {
             Geom::PathVector path_clipboard =  sp_svg_read_pathv(svgd);
             path_clipboard *= item->i2doc_affine().inverse();
             svgd = sp_svg_write_path( path_clipboard );
diff --git a/src/live_effects/parameter/point.cpp b/src/live_effects/parameter/point.cpp
index fe0699a19..a195d663b 100644
--- a/src/live_effects/parameter/point.cpp
+++ b/src/live_effects/parameter/point.cpp
@@ -25,7 +25,7 @@ PointParam::PointParam( const Glib::ustring& label, const Glib::ustring& tip,
     :   Parameter(label, tip, key, wr, effect), 
         defvalue(default_value),
         liveupdate(live_update),
-        _knot_entity(NULL)
+        _knot_entity(nullptr)
 {
     knot_shape = SP_KNOT_SHAPE_DIAMOND;
     knot_mode  = SP_KNOT_MODE_XOR;
@@ -185,7 +185,7 @@ PointParam::set_oncanvas_looks(SPKnotShapeType shape, SPKnotModeType mode, guint
 class PointParamKnotHolderEntity : public KnotHolderEntity {
 public:
     PointParamKnotHolderEntity(PointParam *p) { this->pparam = p; }
-    ~PointParamKnotHolderEntity() override { this->pparam->_knot_entity = NULL;}
+    ~PointParamKnotHolderEntity() override { this->pparam->_knot_entity = nullptr;}
 
     void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
     Geom::Point knot_get() const override;
@@ -239,7 +239,7 @@ PointParam::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     _knot_entity = new PointParamKnotHolderEntity(this);
     // TODO: can we ditch handleTip() etc. because we have access to handle_tip etc. itself???
-    _knot_entity->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, handleTip(), knot_shape, knot_mode, knot_color);
+    _knot_entity->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, handleTip(), knot_shape, knot_mode, knot_color);
     knotholder->add(_knot_entity);
 }
 
diff --git a/src/live_effects/parameter/point.h b/src/live_effects/parameter/point.h
index 4f93b5354..7c620f502 100644
--- a/src/live_effects/parameter/point.h
+++ b/src/live_effects/parameter/point.h
@@ -29,7 +29,7 @@ public:
                 const Glib::ustring& key,
                 Inkscape::UI::Widget::Registry* wr,
                 Effect* effect,
-                const gchar *handle_tip = NULL,// tip for automatically associated on-canvas handle
+                const gchar *handle_tip = nullptr,// tip for automatically associated on-canvas handle
                 Geom::Point default_value = Geom::Point(0,0), 
                 bool live_update = true );
     ~PointParam() override;
diff --git a/src/live_effects/parameter/powerstrokepointarray.cpp b/src/live_effects/parameter/powerstrokepointarray.cpp
index cf4adc5fd..0857deab5 100644
--- a/src/live_effects/parameter/powerstrokepointarray.cpp
+++ b/src/live_effects/parameter/powerstrokepointarray.cpp
@@ -39,7 +39,7 @@ PowerStrokePointArrayParam::~PowerStrokePointArrayParam()
 Gtk::Widget *
 PowerStrokePointArrayParam::param_newWidget()
 {
-    return NULL;
+    return nullptr;
 }
 
 void PowerStrokePointArrayParam::param_transform_multiply(Geom::Affine const &postmul, bool /*set*/)
@@ -280,7 +280,7 @@ void PowerStrokePointArrayParam::addKnotHolderEntities(KnotHolder *knotholder, S
 {
     for (unsigned int i = 0; i < _vector.size(); ++i) {
         PowerStrokePointArrayParamKnotHolderEntity *e = new PowerStrokePointArrayParamKnotHolderEntity(this, i);
-        e->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
+        e->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                    _("<b>Stroke width control point</b>: drag to alter the stroke width. <b>Ctrl+click</b> adds a control point, <b>Ctrl+Alt+click</b> deletes it, <b>Shift+click</b> launches width dialog."),
                    knot_shape, knot_mode, knot_color);
         knotholder->add(e);
diff --git a/src/live_effects/parameter/satellitesarray.cpp b/src/live_effects/parameter/satellitesarray.cpp
index c6f5492d1..10ad0df45 100644
--- a/src/live_effects/parameter/satellitesarray.cpp
+++ b/src/live_effects/parameter/satellitesarray.cpp
@@ -26,7 +26,7 @@ SatellitesArrayParam::SatellitesArrayParam(const Glib::ustring &label,
         const Glib::ustring &key,
         Inkscape::UI::Widget::Registry *wr,
         Effect *effect)
-    : ArrayParam<std::vector<Satellite> >(label, tip, key, wr, effect, 0), _knoth(NULL)
+    : ArrayParam<std::vector<Satellite> >(label, tip, key, wr, effect, 0), _knoth(nullptr)
 {
     _knot_shape = SP_KNOT_SHAPE_DIAMOND;
     _knot_mode = SP_KNOT_MODE_XOR;
@@ -36,7 +36,7 @@ SatellitesArrayParam::SatellitesArrayParam(const Glib::ustring &label,
     _global_knot_hide = false;
     _current_zoom = 0;
     _effectType = FILLET_CHAMFER;
-    _last_pathvector_satellites = NULL;
+    _last_pathvector_satellites = nullptr;
     param_widget_is_visible(false);
 }
 
@@ -269,7 +269,7 @@ void SatellitesArrayParam::addKnotHolderEntities(KnotHolder *knotholder,
                             "<b>Ctrl+Alt+Click</b> reset");
                 }
                 FilletChamferKnotHolderEntity *e = new FilletChamferKnotHolderEntity(this, index);
-                e->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _(tip),_knot_shape, _knot_mode, _knot_color);
+                e->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _(tip),_knot_shape, _knot_mode, _knot_color);
                 knotholder->add(e);
             }
             index++;
diff --git a/src/live_effects/parameter/satellitesarray.h b/src/live_effects/parameter/satellitesarray.h
index 30e196e41..005ea63ff 100644
--- a/src/live_effects/parameter/satellitesarray.h
+++ b/src/live_effects/parameter/satellitesarray.h
@@ -38,7 +38,7 @@ public:
 
     Gtk::Widget *param_newWidget() override
     {
-        return NULL;
+        return nullptr;
     }
     virtual void setHelperSize(int hs);
     void addKnotHolderEntities(KnotHolder *knotholder, SPItem *item) override;
@@ -87,7 +87,7 @@ public:
     FilletChamferKnotHolderEntity(SatellitesArrayParam *p, size_t index);
     ~FilletChamferKnotHolderEntity() override
     {
-        _pparam->_knoth = NULL;
+        _pparam->_knoth = nullptr;
     }
 
     void knot_set(Geom::Point const &p, Geom::Point const &origin,
diff --git a/src/live_effects/parameter/text.h b/src/live_effects/parameter/text.h
index cd1176bc2..fda470638 100644
--- a/src/live_effects/parameter/text.h
+++ b/src/live_effects/parameter/text.h
@@ -73,9 +73,9 @@ private:
 class TextParamInternal : public TextParam {
 public:
     TextParamInternal(Effect* effect) :
-        TextParam("", "", "", NULL, effect) {}
+        TextParam("", "", "", nullptr, effect) {}
 
-    Gtk::Widget * param_newWidget() override { return NULL; }
+    Gtk::Widget * param_newWidget() override { return nullptr; }
 };
 
 } //namespace LivePathEffect
diff --git a/src/live_effects/parameter/togglebutton.cpp b/src/live_effects/parameter/togglebutton.cpp
index bb9d9a90e..b5f7f5998 100644
--- a/src/live_effects/parameter/togglebutton.cpp
+++ b/src/live_effects/parameter/togglebutton.cpp
@@ -29,7 +29,7 @@ ToggleButtonParam::ToggleButtonParam( const Glib::ustring& label, const Glib::us
     : Parameter(label, tip, key, wr, effect), value(default_value), defvalue(default_value),
       inactive_label(inactive_label), _icon_active(_icon_active), _icon_inactive(_icon_inactive), _icon_size(_icon_size)
 {
-    checkwdg = NULL;
+    checkwdg = nullptr;
 }
 
 ToggleButtonParam::~ToggleButtonParam()
@@ -107,7 +107,7 @@ ToggleButtonParam::param_newWidget()
             _icon_inactive = _icon_active;
         }
         gtk_widget_show(box_button);
-        GtkWidget *icon_button = NULL;
+        GtkWidget *icon_button = nullptr;
         if(!value){ 
             icon_button = gtk_image_new_from_icon_name(_icon_inactive, _icon_size);
         } else {
@@ -156,7 +156,7 @@ ToggleButtonParam::refresh_button()
         }
     }
     if ( _icon_active ) {
-        GdkPixbuf * icon_pixbuf = NULL;
+        GdkPixbuf * icon_pixbuf = nullptr;
         Gtk::Image *im = dynamic_cast<Gtk::Image*>(children[0]);
         Gtk::IconSize is(_icon_size);
         if (!im) return;
diff --git a/src/live_effects/parameter/togglebutton.h b/src/live_effects/parameter/togglebutton.h
index 7476698f5..29ee72203 100644
--- a/src/live_effects/parameter/togglebutton.h
+++ b/src/live_effects/parameter/togglebutton.h
@@ -31,8 +31,8 @@ public:
                Effect* effect,
                bool default_value = false,
                const Glib::ustring& inactive_label = "",
-               char const * icon_active = NULL,
-               char const * icon_inactive = NULL,
+               char const * icon_active = nullptr,
+               char const * icon_inactive = nullptr,
                GtkIconSize icon_size = GTK_ICON_SIZE_SMALL_TOOLBAR);
     ~ToggleButtonParam() override;
 
diff --git a/src/live_effects/parameter/vector.cpp b/src/live_effects/parameter/vector.cpp
index 56895276c..8018ed618 100644
--- a/src/live_effects/parameter/vector.cpp
+++ b/src/live_effects/parameter/vector.cpp
@@ -216,11 +216,11 @@ void
 VectorParam::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
 {
     VectorParamKnotHolderEntity_Origin *origin_e = new VectorParamKnotHolderEntity_Origin(this);
-    origin_e->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, handleTip(), ori_knot_shape, ori_knot_mode, ori_knot_color);
+    origin_e->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, handleTip(), ori_knot_shape, ori_knot_mode, ori_knot_color);
     knotholder->add(origin_e);
 
     VectorParamKnotHolderEntity_Vector *vector_e = new VectorParamKnotHolderEntity_Vector(this);
-    vector_e->create(NULL, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, handleTip(), vec_knot_shape, vec_knot_mode, vec_knot_color);
+    vector_e->create(nullptr, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, handleTip(), vec_knot_shape, vec_knot_mode, vec_knot_color);
     knotholder->add(vector_e);
 }