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

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

10 files changed, 147 insertions, 147 deletions

diff --git a/src/extension/param/bool.cpp b/src/extension/param/bool.cpp
index 80bc89138..eea660f69 100644
--- a/src/extension/param/bool.cpp
+++ b/src/extension/param/bool.cpp
@@ -33,12 +33,12 @@ ParamBool::ParamBool(const gchar * name,
     : Parameter(name, text, description, hidden, indent, ext)
     , _value(false)
 {
-    const char * defaultval = NULL;
-    if (xml->firstChild() != NULL) {
+    const char * defaultval = nullptr;
+    if (xml->firstChild() != nullptr) {
         defaultval = xml->firstChild()->content();
     }
 
-    if (defaultval != NULL && (!strcmp(defaultval, "true") || !strcmp(defaultval, "1"))) {
+    if (defaultval != nullptr && (!strcmp(defaultval, "true") || !strcmp(defaultval, "1"))) {
         _value = true;
     } else {
         _value = false;
@@ -85,7 +85,7 @@ public:
      */
     ParamBoolCheckButton (ParamBool * param, gchar * label, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
             Gtk::CheckButton(label), _pref(param), _doc(doc), _node(node), _changeSignal(changeSignal) {
-        this->set_active(_pref->get(NULL, NULL) /**\todo fix */);
+        this->set_active(_pref->get(nullptr, nullptr) /**\todo fix */);
         this->signal_toggled().connect(sigc::mem_fun(this, &ParamBoolCheckButton::on_toggle));
         return;
     }
@@ -106,8 +106,8 @@ private:
 
 void ParamBoolCheckButton::on_toggle(void)
 {
-    _pref->set(this->get_active(), NULL /**\todo fix this */, NULL);
-    if (_changeSignal != NULL) {
+    _pref->set(this->get_active(), nullptr /**\todo fix this */, nullptr);
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
     return;
@@ -127,7 +127,7 @@ void ParamBool::string(std::string &string) const
 Gtk::Widget *ParamBool::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     auto hbox = Gtk::manage(new Gtk::Box(Gtk::ORIENTATION_HORIZONTAL, Parameter::GUI_PARAM_WIDGETS_SPACING));
diff --git a/src/extension/param/color.cpp b/src/extension/param/color.cpp
index 035c43ba8..1e3b1dc4c 100644
--- a/src/extension/param/color.cpp
+++ b/src/extension/param/color.cpp
@@ -60,10 +60,10 @@ ParamColor::ParamColor(const gchar * name,
                        Inkscape::Extension::Extension * ext,
                        Inkscape::XML::Node * xml)
     : Parameter(name, text, description, hidden, indent, ext)
-    , _changeSignal(0)
+    , _changeSignal(nullptr)
 {
-    const char * defaulthex = NULL;
-    if (xml->firstChild() != NULL)
+    const char * defaulthex = nullptr;
+    if (xml->firstChild() != nullptr)
         defaulthex = xml->firstChild()->content();
 
     gchar * pref_name = this->pref_name();
@@ -92,7 +92,7 @@ Gtk::Widget *ParamColor::get_widget( SPDocument * /*doc*/, Inkscape::XML::Node *
 {
     using Inkscape::UI::Widget::ColorNotebook;
 
-    if (_hidden) return NULL;
+    if (_hidden) return nullptr;
 
     if (changeSignal) {
         _changeSignal = new sigc::signal<void>(*changeSignal);
diff --git a/src/extension/param/description.cpp b/src/extension/param/description.cpp
index cf94918f7..d795514c3 100644
--- a/src/extension/param/description.cpp
+++ b/src/extension/param/description.cpp
@@ -37,15 +37,15 @@ ParamDescription::ParamDescription(const gchar * name,
                                    Inkscape::XML::Node * xml,
                                    AppearanceMode mode)
     : Parameter(name, text, description, hidden, indent, ext)
-    , _value(NULL)
+    , _value(nullptr)
     , _mode(mode)
 {
     // construct the text content by concatenating all (non-empty) text nodes,
     // removing all other nodes (e.g. comment nodes) and replacing <extension:br> elements with "<br/>"
     Glib::ustring value;
     Inkscape::XML::Node * cur_child = xml->firstChild();
-    while (cur_child != NULL) {
-        if (cur_child->type() == XML::TEXT_NODE && cur_child->content() != NULL) {
+    while (cur_child != nullptr) {
+        if (cur_child->type() == XML::TEXT_NODE && cur_child->content() != nullptr) {
             value += cur_child->content();
         } else if (cur_child->type() == XML::ELEMENT_NODE && !g_strcmp0(cur_child->name(), "extension:br")) {
             value += "<br/>";
@@ -71,8 +71,8 @@ ParamDescription::ParamDescription(const gchar * name,
     // translate if underscored version (_param) was used
     if (g_str_has_prefix(xml->name(), "extension:_")) {
         const gchar * context = xml->attribute("msgctxt");
-        if (context != NULL) {
-            value = g_dpgettext2(NULL, context, value.c_str());
+        if (context != nullptr) {
+            value = g_dpgettext2(nullptr, context, value.c_str());
         } else {
             value = _(value.c_str());
         }
@@ -91,10 +91,10 @@ Gtk::Widget *
 ParamDescription::get_widget (SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/, sigc::signal<void> * /*changeSignal*/)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
-    if (_value == NULL) {
-        return NULL;
+    if (_value == nullptr) {
+        return nullptr;
     }
 
     Glib::ustring newtext = _value;
diff --git a/src/extension/param/enum.cpp b/src/extension/param/enum.cpp
index ddcbb358b..c5ee5f6b9 100644
--- a/src/extension/param/enum.cpp
+++ b/src/extension/param/enum.cpp
@@ -39,27 +39,27 @@ ParamComboBox::ParamComboBox(const gchar * name,
                              Inkscape::Extension::Extension * ext,
                              Inkscape::XML::Node * xml)
     : Parameter(name, text, description, hidden, indent, ext)
-    , _value(NULL)
+    , _value(nullptr)
 {
-    const char *xmlval = NULL; // the value stored in XML
+    const char *xmlval = nullptr; // the value stored in XML
 
-    if (xml != NULL) {
+    if (xml != nullptr) {
         // Read XML tree to add enumeration items:
         for (Inkscape::XML::Node *node = xml->firstChild(); node; node = node->next()) {
             char const * chname = node->name();
             if (!strcmp(chname, INKSCAPE_EXTENSION_NS "item") || !strcmp(chname, INKSCAPE_EXTENSION_NS "_item")) {
                 Glib::ustring newtext, newvalue;
-                const char * contents = NULL;
+                const char * contents = nullptr;
                 if (node->firstChild()) {
                     contents = node->firstChild()->content();
                 }
-                if (contents != NULL) {
+                if (contents != nullptr) {
                     // don't translate when 'item' but do translate when '_item'
                     // NOTE: internal extensions use build_from_mem and don't need _item but
                     //       still need to include if are to be localized
                     if (!strcmp(chname, INKSCAPE_EXTENSION_NS "_item")) {
-                        if (node->attribute("msgctxt") != NULL) {
-                            newtext =  g_dpgettext2(NULL, node->attribute("msgctxt"), contents);
+                        if (node->attribute("msgctxt") != nullptr) {
+                            newtext =  g_dpgettext2(nullptr, node->attribute("msgctxt"), contents);
                         } else {
                             newtext =  _(contents);
                         }
@@ -70,7 +70,7 @@ ParamComboBox::ParamComboBox(const gchar * name,
                     continue;
 
                 const char * val = node->attribute("value");
-                if (val != NULL) {
+                if (val != nullptr) {
                     newvalue = val;
                 } else {
                     newvalue = contents;
@@ -128,8 +128,8 @@ ParamComboBox::~ParamComboBox (void)
  */
 const gchar *ParamComboBox::set(const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
-    if (in == NULL) {
-        return NULL; /* Can't have NULL string */
+    if (in == nullptr) {
+        return nullptr; /* Can't have NULL string */
     }
 
     Glib::ustring settext;
@@ -140,7 +140,7 @@ const gchar *ParamComboBox::set(const gchar * in, SPDocument * /*doc*/, Inkscape
         }
     }
     if (!settext.empty()) {
-        if (_value != NULL) {
+        if (_value != nullptr) {
             g_free(_value);
         }
         _value = g_strdup(settext.data());
@@ -158,7 +158,7 @@ const gchar *ParamComboBox::set(const gchar * in, SPDocument * /*doc*/, Inkscape
  */
 bool ParamComboBox::contains(const gchar * text, SPDocument const * /*doc*/, Inkscape::XML::Node const * /*node*/) const
 {
-    if (text == NULL) {
+    if (text == nullptr) {
         return false; /* Can't have NULL string */
     }
 
@@ -214,7 +214,7 @@ ParamComboBoxEntry::changed (void)
 {
     Glib::ustring data = this->get_active_text();
     _pref->set(data.c_str(), _doc, _node);
-    if (_changeSignal != NULL) {
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
 }
@@ -225,7 +225,7 @@ ParamComboBoxEntry::changed (void)
 Gtk::Widget *ParamComboBox::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     Gtk::HBox * hbox = Gtk::manage(new Gtk::HBox(false, Parameter::GUI_PARAM_WIDGETS_SPACING));
diff --git a/src/extension/param/float.cpp b/src/extension/param/float.cpp
index 1dd3f073b..aaf871068 100644
--- a/src/extension/param/float.cpp
+++ b/src/extension/param/float.cpp
@@ -40,27 +40,27 @@ ParamFloat::ParamFloat(const gchar * name,
     , _min(0.0)
     , _max(10.0)
 {
-    const gchar * defaultval = NULL;
-    if (xml->firstChild() != NULL) {
+    const gchar * defaultval = nullptr;
+    if (xml->firstChild() != nullptr) {
         defaultval = xml->firstChild()->content();
     }
-    if (defaultval != NULL) {
-        _value = g_ascii_strtod (defaultval,NULL);
+    if (defaultval != nullptr) {
+        _value = g_ascii_strtod (defaultval,nullptr);
     }
 
     const char * maxval = xml->attribute("max");
-    if (maxval != NULL) {
-        _max = g_ascii_strtod (maxval,NULL);
+    if (maxval != nullptr) {
+        _max = g_ascii_strtod (maxval,nullptr);
     }
 
     const char * minval = xml->attribute("min");
-    if (minval != NULL) {
-        _min = g_ascii_strtod (minval,NULL);
+    if (minval != nullptr) {
+        _min = g_ascii_strtod (minval,nullptr);
     }
 
     _precision = 1;
     const char * precision = xml->attribute("precision");
-    if (precision != NULL) {
+    if (precision != nullptr) {
         _precision = atoi(precision);
     }
 
@@ -136,7 +136,7 @@ public:
                 describing the parameter. */
     ParamFloatAdjustment (ParamFloat * param, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
             Gtk::Adjustment(0.0, param->min(), param->max(), 0.1, 1.0, 0), _pref(param), _doc(doc), _node(node), _changeSignal(changeSignal) {
-        this->set_value(_pref->get(NULL, NULL) /* \todo fix */);
+        this->set_value(_pref->get(nullptr, nullptr) /* \todo fix */);
         this->signal_value_changed().connect(sigc::mem_fun(this, &ParamFloatAdjustment::val_changed));
         return;
     };
@@ -154,7 +154,7 @@ void ParamFloatAdjustment::val_changed(void)
 {
     //std::cout << "Value Changed to: " << this->get_value() << std::endl;
     _pref->set(this->get_value(), _doc, _node);
-    if (_changeSignal != NULL) {
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
     return;
@@ -168,7 +168,7 @@ void ParamFloatAdjustment::val_changed(void)
 Gtk::Widget * ParamFloat::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     Gtk::HBox * hbox = Gtk::manage(new Gtk::HBox(false, Parameter::GUI_PARAM_WIDGETS_SPACING));
@@ -179,7 +179,7 @@ Gtk::Widget * ParamFloat::get_widget(SPDocument * doc, Inkscape::XML::Node * nod
     if (_mode == FULL) {
 
         Glib::ustring text;
-        if (_text != NULL)
+        if (_text != nullptr)
             text = _text;
         UI::Widget::SpinScale *scale = new UI::Widget::SpinScale(text, fadjust, _precision);
         scale->set_size_request(400, -1);
diff --git a/src/extension/param/int.cpp b/src/extension/param/int.cpp
index 9ad9b591c..1c946d8b8 100644
--- a/src/extension/param/int.cpp
+++ b/src/extension/param/int.cpp
@@ -40,21 +40,21 @@ ParamInt::ParamInt(const gchar * name,
     , _min(0)
     , _max(10)
 {
-    const char * defaultval = NULL;
-    if (xml->firstChild() != NULL) {
+    const char * defaultval = nullptr;
+    if (xml->firstChild() != nullptr) {
         defaultval = xml->firstChild()->content();
     }
-    if (defaultval != NULL) {
+    if (defaultval != nullptr) {
         _value = atoi(defaultval);
     }
 
     const char * maxval = xml->attribute("max");
-    if (maxval != NULL) {
+    if (maxval != nullptr) {
         _max = atoi(maxval);
     }
 
     const char * minval = xml->attribute("min");
-    if (minval != NULL) {
+    if (minval != nullptr) {
         _min = atoi(minval);
     }
     /* We're handling this by just killing both values */
@@ -118,7 +118,7 @@ public:
         describing the parameter. */
     ParamIntAdjustment (ParamInt * param, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
             Gtk::Adjustment(0.0, param->min(), param->max(), 1.0, 10.0, 0), _pref(param), _doc(doc), _node(node), _changeSignal(changeSignal) {
-        this->set_value(_pref->get(NULL, NULL) /* \todo fix */);
+        this->set_value(_pref->get(nullptr, nullptr) /* \todo fix */);
         this->signal_value_changed().connect(sigc::mem_fun(this, &ParamIntAdjustment::val_changed));
     };
 
@@ -135,7 +135,7 @@ void ParamIntAdjustment::val_changed(void)
 {
     //std::cout << "Value Changed to: " << this->get_value() << std::endl;
     _pref->set((int)this->get_value(), _doc, _node);
-    if (_changeSignal != NULL) {
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
 }
@@ -149,7 +149,7 @@ Gtk::Widget *
 ParamInt::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     Gtk::HBox * hbox = Gtk::manage(new Gtk::HBox(false, Parameter::GUI_PARAM_WIDGETS_SPACING));
@@ -160,7 +160,7 @@ ParamInt::get_widget (SPDocument * doc, Inkscape::XML::Node * node, sigc::signal
     if (_mode == FULL) {
 
         Glib::ustring text;
-        if (_text != NULL)
+        if (_text != nullptr)
             text = _text;
         UI::Widget::SpinScale *scale = new UI::Widget::SpinScale(text, fadjust, 0);
         scale->set_size_request(400, -1);
diff --git a/src/extension/param/notebook.cpp b/src/extension/param/notebook.cpp
index e47644f45..d00693db4 100644
--- a/src/extension/param/notebook.cpp
+++ b/src/extension/param/notebook.cpp
@@ -51,9 +51,9 @@ ParamNotebook::ParamNotebookPage::ParamNotebookPage(const gchar * name,
 {
 
     // Read XML to build page
-    if (xml != NULL) {
+    if (xml != nullptr) {
         Inkscape::XML::Node *child_repr = xml->firstChild();
-        while (child_repr != NULL) {
+        while (child_repr != nullptr) {
             char const * chname = child_repr->name();
             if (!strncmp(chname, INKSCAPE_EXTENSION_NS_NC, strlen(INKSCAPE_EXTENSION_NS_NC))) {
                 chname += strlen(INKSCAPE_EXTENSION_NS);
@@ -63,7 +63,7 @@ ParamNotebook::ParamNotebookPage::ParamNotebookPage(const gchar * name,
             if (!strcmp(chname, "param") || !strcmp(chname, "_param")) {
                 Parameter * param;
                 param = Parameter::make(child_repr, ext);
-                if (param != NULL) parameters.push_back(param);
+                if (param != nullptr) parameters.push_back(param);
             }
             child_repr = child_repr->next();
         }
@@ -122,13 +122,13 @@ ParamNotebook::ParamNotebookPage::makepage (Inkscape::XML::Node * in_repr, Inksc
 
     name = in_repr->attribute("name");
     text = in_repr->attribute("gui-text");
-    if (text == NULL)
+    if (text == nullptr)
         text = in_repr->attribute("_gui-text");
     description = in_repr->attribute("gui-description");
-    if (description == NULL)
+    if (description == nullptr)
         description = in_repr->attribute("_gui-description");
     hide = in_repr->attribute("gui-hidden");
-    if (hide != NULL) {
+    if (hide != nullptr) {
         if (strcmp(hide, "1") == 0 ||
             strcmp(hide, "true") == 0) {
                 hidden = true;
@@ -137,8 +137,8 @@ ParamNotebook::ParamNotebookPage::makepage (Inkscape::XML::Node * in_repr, Inksc
     }
 
     /* In this case we just don't have enough information */
-    if (name == NULL) {
-        return NULL;
+    if (name == nullptr) {
+        return nullptr;
     }
 
     ParamNotebookPage * page = new ParamNotebookPage(name, text, description, hidden, in_ext, in_repr);
@@ -157,7 +157,7 @@ ParamNotebook::ParamNotebookPage::makepage (Inkscape::XML::Node * in_repr, Inksc
 Gtk::Widget * ParamNotebook::ParamNotebookPage::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     Gtk::VBox * vbox = Gtk::manage(new Gtk::VBox);
@@ -194,7 +194,7 @@ Gtk::Widget * ParamNotebook::ParamNotebookPage::get_widget(SPDocument * doc, Ink
 /** Search the parameter's name in the page content. */
 Parameter *ParamNotebook::ParamNotebookPage::get_param(const gchar * name)
 {
-    if (name == NULL) {
+    if (name == nullptr) {
         throw Extension::param_not_exist();
     }
     if (this->parameters.empty()) {
@@ -208,7 +208,7 @@ Parameter *ParamNotebook::ParamNotebookPage::get_param(const gchar * name)
         }
     }
 
-    return NULL;
+    return nullptr;
 }
 
 /** End ParamNotebookPage **/
@@ -224,9 +224,9 @@ ParamNotebook::ParamNotebook(const gchar * name,
     : Parameter(name, text, description, hidden, indent, ext)
 {
     // Read XML tree to add pages:
-    if (xml != NULL) {
+    if (xml != nullptr) {
         Inkscape::XML::Node *child_repr = xml->firstChild();
-        while (child_repr != NULL) {
+        while (child_repr != nullptr) {
             char const * chname = child_repr->name();
             if (!strncmp(chname, INKSCAPE_EXTENSION_NS_NC, strlen(INKSCAPE_EXTENSION_NS_NC))) {
                 chname += strlen(INKSCAPE_EXTENSION_NS);
@@ -236,14 +236,14 @@ ParamNotebook::ParamNotebook(const gchar * name,
             if (!strcmp(chname, "page")) {
                 ParamNotebookPage * page;
                 page = ParamNotebookPage::makepage(child_repr, ext);
-                if (page != NULL) pages.push_back(page);
+                if (page != nullptr) pages.push_back(page);
             }
             child_repr = child_repr->next();
         }
     }
 
     // Initialize _value with the current page
-    const char * defaultval = NULL;
+    const char * defaultval = nullptr;
     // set first page as default
     if (!pages.empty()) {
         defaultval = pages[0]->name();
@@ -256,7 +256,7 @@ ParamNotebook::ParamNotebook(const gchar * name,
 
     if (!paramval.empty())
         defaultval = paramval.data();
-    if (defaultval != NULL)
+    if (defaultval != nullptr)
         _value = g_strdup(defaultval);  // allocate space for _value
 }
 
@@ -290,9 +290,9 @@ const gchar *ParamNotebook::set(const int in, SPDocument * /*doc*/, Inkscape::XM
     int i = in < pages.size() ? in : pages.size()-1;
     ParamNotebookPage * page = pages[i];
 
-    if (page == NULL) return _value;
+    if (page == nullptr) return _value;
 
-    if (_value != NULL) g_free(_value);
+    if (_value != nullptr) g_free(_value);
     _value = g_strdup(page->name());
 
     gchar * prefname = this->pref_name();
@@ -359,7 +359,7 @@ void ParamNotebookWdg::changed_page(Gtk::Widget * /*page*/, guint pagenum)
 /** Search the parameter's name in the notebook content. */
 Parameter *ParamNotebook::get_param(const gchar * name)
 {
-    if (name == NULL) {
+    if (name == nullptr) {
         throw Extension::param_not_exist();
     }
     for (auto page:pages) {
@@ -369,7 +369,7 @@ Parameter *ParamNotebook::get_param(const gchar * name)
         }
     }
 
-    return NULL;
+    return nullptr;
 }
 
 
@@ -381,7 +381,7 @@ Parameter *ParamNotebook::get_param(const gchar * name)
 Gtk::Widget * ParamNotebook::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     ParamNotebookWdg * nb = Gtk::manage(new ParamNotebookWdg(this, doc, node));
diff --git a/src/extension/param/parameter.cpp b/src/extension/param/parameter.cpp
index f9a69de05..d897903cb 100644
--- a/src/extension/param/parameter.cpp
+++ b/src/extension/param/parameter.cpp
@@ -52,37 +52,37 @@ Parameter *Parameter::make(Inkscape::XML::Node *in_repr, Inkscape::Extension::Ex
 
     // we can't create a parameter without type
     if (!type) {
-        return NULL;
+        return nullptr;
     }
     // also require name unless it's a pure UI element that does not store its value
     if (!name) {
         static std::vector<std::string> ui_elements = {"description"};
         if (std::find(ui_elements.begin(), ui_elements.end(), type) == ui_elements.end()) {
-            return NULL;
+            return nullptr;
         }
     }
 
     const char *text = in_repr->attribute("gui-text");
-    if (text == NULL) {
+    if (text == nullptr) {
         text = in_repr->attribute("_gui-text");
-        if (text == NULL) {
+        if (text == nullptr) {
             // text = ""; // probably better to require devs to explicitly set an empty gui-text if this is what they want
         } else {
             const char *context = in_repr->attribute("msgctxt");
-            if (context != NULL) {
-                text = g_dpgettext2(NULL, context, text);
+            if (context != nullptr) {
+                text = g_dpgettext2(nullptr, context, text);
             } else {
                 text = _(text);
             }
         }
     }
     const char *description = in_repr->attribute("gui-description");
-    if (description == NULL) {
+    if (description == nullptr) {
         description = in_repr->attribute("_gui-description");
-        if (description != NULL) {
+        if (description != nullptr) {
             const char *context = in_repr->attribute("msgctxt");
-            if (context != NULL) {
-                description = g_dpgettext2(NULL, context, description);
+            if (context != nullptr) {
+                description = g_dpgettext2(nullptr, context, description);
             } else {
                 description = _(description);
             }
@@ -91,7 +91,7 @@ Parameter *Parameter::make(Inkscape::XML::Node *in_repr, Inkscape::Extension::Ex
     bool hidden = false;
     {
         const char *gui_hide = in_repr->attribute("gui-hidden");
-        if (gui_hide != NULL) {
+        if (gui_hide != nullptr) {
             if (strcmp(gui_hide, "1") == 0 ||
                 strcmp(gui_hide, "true") == 0) {
                 hidden = true;
@@ -102,7 +102,7 @@ Parameter *Parameter::make(Inkscape::XML::Node *in_repr, Inkscape::Extension::Ex
     int indent = 0;
     {
         const char *indent_attr = in_repr->attribute("indent");
-        if (indent_attr != NULL) {
+        if (indent_attr != nullptr) {
             if (strcmp(indent_attr, "true") == 0) {
                 indent = 1;
             } else {
@@ -112,7 +112,7 @@ Parameter *Parameter::make(Inkscape::XML::Node *in_repr, Inkscape::Extension::Ex
     }
     const gchar* appearance = in_repr->attribute("appearance");
 
-    Parameter * param = NULL;
+    Parameter * param = nullptr;
     if (!strcmp(type, "boolean")) {
         param = new ParamBool(name, text, description, hidden, indent, in_ext, in_repr);
     } else if (!strcmp(type, "int")) {
@@ -130,7 +130,7 @@ Parameter *Parameter::make(Inkscape::XML::Node *in_repr, Inkscape::Extension::Ex
     } else if (!strcmp(type, "string")) {
         param = new ParamString(name, text, description, hidden, indent, in_ext, in_repr);
         gchar const * max_length = in_repr->attribute("max_length");
-        if (max_length != NULL) {
+        if (max_length != nullptr) {
             ParamString * ps = dynamic_cast<ParamString *>(param);
             ps->setMaxLength(atoi(max_length));
         }
@@ -237,7 +237,7 @@ guint32 Parameter::get_color(const SPDocument* doc, Inkscape::XML::Node const *n
 bool Parameter::set_bool(bool in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamBool * boolpntr = dynamic_cast<ParamBool *>(this);
-    if (boolpntr == NULL)
+    if (boolpntr == nullptr)
         throw Extension::param_not_bool_param();
     return boolpntr->set(in, doc, node);
 }
@@ -245,7 +245,7 @@ bool Parameter::set_bool(bool in, SPDocument * doc, Inkscape::XML::Node * node)
 int Parameter::set_int(int in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamInt * intpntr = dynamic_cast<ParamInt *>(this);
-    if (intpntr == NULL)
+    if (intpntr == nullptr)
         throw Extension::param_not_int_param();
     return intpntr->set(in, doc, node);
 }
@@ -256,7 +256,7 @@ Parameter::set_float (float in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamFloat * floatpntr;
     floatpntr = dynamic_cast<ParamFloat *>(this);
-    if (floatpntr == NULL)
+    if (floatpntr == nullptr)
         throw Extension::param_not_float_param();
     return floatpntr->set(in, doc, node);
 }
@@ -266,7 +266,7 @@ gchar const *
 Parameter::set_string (gchar const * in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamString * stringpntr = dynamic_cast<ParamString *>(this);
-    if (stringpntr == NULL)
+    if (stringpntr == nullptr)
         throw Extension::param_not_string_param();
     return stringpntr->set(in, doc, node);
 }
@@ -295,7 +295,7 @@ guint32
 Parameter::set_color (guint32 in, SPDocument * doc, Inkscape::XML::Node * node)
 {
     ParamColor* param = dynamic_cast<ParamColor *>(this);
-    if (param == NULL)
+    if (param == nullptr)
         throw Extension::param_not_color_param();
     return param->set(in, doc, node);
 }
@@ -303,22 +303,22 @@ Parameter::set_color (guint32 in, SPDocument * doc, Inkscape::XML::Node * node)
 
 /** Oop, now that we need a parameter, we need it's name. */
 Parameter::Parameter(gchar const * name, gchar const * text, gchar const * description, bool hidden, int indent, Inkscape::Extension::Extension * ext) :
-    _description(0),
-    _text(0),
+    _description(nullptr),
+    _text(nullptr),
     _hidden(hidden),
     _indent(indent),
     _extension(ext),
-    _name(0)
+    _name(nullptr)
 {
-    if (name != NULL) {
+    if (name != nullptr) {
         _name = g_strdup(name);
     }
 
-    if (description != NULL) {
+    if (description != nullptr) {
         _description = g_strdup(description);
     }
 
-    if (text != NULL) {
+    if (text != nullptr) {
         _text = g_strdup(text);
     } else {
         _text = g_strdup(name);
@@ -329,17 +329,17 @@ Parameter::Parameter(gchar const * name, gchar const * text, gchar const * descr
 
 /** Oop, now that we need a parameter, we need it's name. */
 Parameter::Parameter (gchar const * name, gchar const * text, Inkscape::Extension::Extension * ext) :
-    _description(0),
-    _text(0),
+    _description(nullptr),
+    _text(nullptr),
     _hidden(false),
     _indent(0),
     _extension(ext),
-    _name(0)
+    _name(nullptr)
 {
-    if (name != NULL) {
+    if (name != nullptr) {
         _name = g_strdup(name);
     }
-    if (text != NULL) {
+    if (text != nullptr) {
         _text = g_strdup(text);
     } else {
         _text = g_strdup(name);
@@ -351,13 +351,13 @@ Parameter::Parameter (gchar const * name, gchar const * text, Inkscape::Extensio
 Parameter::~Parameter(void)
 {
     g_free(_name);
-    _name = 0;
+    _name = nullptr;
 
     g_free(_text);
-    _text = 0;
+    _text = nullptr;
 
     g_free(_description);
-    _description = 0;
+    _description = nullptr;
 }
 
 gchar *Parameter::pref_name(void) const
@@ -387,12 +387,12 @@ Inkscape::XML::Node *Parameter::document_param_node(SPDocument * doc)
 {
     Inkscape::XML::Document *xml_doc = doc->getReprDoc();
     Inkscape::XML::Node * defs = doc->getDefs()->getRepr();
-    Inkscape::XML::Node * params = NULL;
+    Inkscape::XML::Node * params = nullptr;
 
     GQuark const name_quark = g_quark_from_string("inkscape:extension-params");
 
     for (Inkscape::XML::Node * child = defs->firstChild();
-            child != NULL;
+            child != nullptr;
             child = child->next()) {
         if ((GQuark)child->code() == name_quark &&
                 !strcmp(child->attribute("extension"), _extension->get_id())) {
@@ -401,7 +401,7 @@ Inkscape::XML::Node *Parameter::document_param_node(SPDocument * doc)
         }
     }
 
-    if (params == NULL) {
+    if (params == nullptr) {
         params = xml_doc->createElement("inkscape:extension-param");
         params->setAttribute("extension", _extension->get_id());
         defs->appendChild(params);
@@ -415,7 +415,7 @@ Inkscape::XML::Node *Parameter::document_param_node(SPDocument * doc)
 Gtk::Widget *
 Parameter::get_widget (SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/, sigc::signal<void> * /*changeSignal*/)
 {
-    return NULL;
+    return nullptr;
 }
 
 /** If I'm not sure which it is, just don't return a value. */
@@ -441,7 +441,7 @@ void Parameter::string(std::list <std::string> &list) const
 
 Parameter *Parameter::get_param(gchar const * /*name*/)
 {
-    return NULL;
+    return nullptr;
 }
 
 Glib::ustring const extension_pref_root = "/extensions/";
diff --git a/src/extension/param/radiobutton.cpp b/src/extension/param/radiobutton.cpp
index 5598081f3..45869378a 100644
--- a/src/extension/param/radiobutton.cpp
+++ b/src/extension/param/radiobutton.cpp
@@ -51,25 +51,25 @@ ParamRadioButton::ParamRadioButton(const gchar * name,
                                    Inkscape::XML::Node * xml,
                                    AppearanceMode mode)
     : Parameter(name, text, description, hidden, indent, ext)
-    , _value(0)
+    , _value(nullptr)
     , _mode(mode)
 {
     // Read XML tree to add enumeration items:
     // printf("Extension Constructor: ");
-    if (xml != NULL) {
+    if (xml != nullptr) {
         Inkscape::XML::Node *child_repr = xml->firstChild();
-        while (child_repr != NULL) {
+        while (child_repr != nullptr) {
             char const * chname = child_repr->name();
             if (!strcmp(chname, INKSCAPE_EXTENSION_NS "option") || !strcmp(chname, INKSCAPE_EXTENSION_NS "_option")) {
-                Glib::ustring * newtext = NULL;
-                Glib::ustring * newvalue = NULL;
+                Glib::ustring * newtext = nullptr;
+                Glib::ustring * newvalue = nullptr;
                 const char * contents = child_repr->firstChild()->content();
 
-                if (contents != NULL) {
+                if (contents != nullptr) {
                     // don't translate when 'item' but do translate when '_option'
                     if (!strcmp(chname, INKSCAPE_EXTENSION_NS "_option")) {
-                        if (child_repr->attribute("msgctxt") != NULL) {
-                            newtext =  new Glib::ustring(g_dpgettext2(NULL, child_repr->attribute("msgctxt"), contents));
+                        if (child_repr->attribute("msgctxt") != nullptr) {
+                            newtext =  new Glib::ustring(g_dpgettext2(nullptr, child_repr->attribute("msgctxt"), contents));
                         } else {
                             newtext =  new Glib::ustring(_(contents));
                         }
@@ -82,7 +82,7 @@ ParamRadioButton::ParamRadioButton(const gchar * name,
 
 
                 const char * val = child_repr->attribute("value");
-                if (val != NULL) {
+                if (val != nullptr) {
                     newvalue = new Glib::ustring(val);
                 } else {
                     newvalue = new Glib::ustring(contents);
@@ -98,7 +98,7 @@ ParamRadioButton::ParamRadioButton(const gchar * name,
 
     // Initialize _value with the default value from xml
     // for simplicity : default to the contents of the first xml-child
-    const char * defaultval = NULL;
+    const char * defaultval = nullptr;
     if (!choices.empty()) {
         defaultval = (static_cast<optionentry*> (choices[0]))->value->c_str();
     }
@@ -111,7 +111,7 @@ ParamRadioButton::ParamRadioButton(const gchar * name,
     if (!paramval.empty()) {
         defaultval = paramval.data();
     }
-    if (defaultval != NULL) {
+    if (defaultval != nullptr) {
         _value = g_strdup(defaultval);  // allocate space for _value
     }
 }
@@ -143,11 +143,11 @@ ParamRadioButton::~ParamRadioButton (void)
  */
 const gchar *ParamRadioButton::set(const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
-    if (in == NULL) {
-        return NULL; /* Can't have NULL string */
+    if (in == nullptr) {
+        return nullptr; /* Can't have NULL string */
     }
 
-    Glib::ustring * settext = NULL;
+    Glib::ustring * settext = nullptr;
     for (auto entr:choices) {
         if ( !entr->value->compare(in) ) {
             settext = entr->value;
@@ -155,7 +155,7 @@ const gchar *ParamRadioButton::set(const gchar * in, SPDocument * /*doc*/, Inksc
         }
     }
     if (settext) {
-        if (_value != NULL) {
+        if (_value != nullptr) {
             g_free(_value);
         }
         _value = g_strdup(settext->c_str());
@@ -215,7 +215,7 @@ void ParamRadioButtonWdg::changed(void)
         Glib::ustring value = _pref->value_from_label(this->get_label());
         _pref->set(value.c_str(), _doc, _node);
     }
-    if (_changeSignal != NULL) {
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
 }
@@ -247,7 +247,7 @@ void ComboWdg::changed(void)
             Glib::ustring value = _base->value_from_label(get_active_text());
             _base->set(value.c_str(), _doc, _node);
     }
-    if (_changeSignal != NULL) {
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
 }
@@ -276,7 +276,7 @@ Glib::ustring ParamRadioButton::value_from_label(const Glib::ustring label)
 Gtk::Widget * ParamRadioButton::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     auto hbox = Gtk::manage(new Gtk::Box(Gtk::ORIENTATION_HORIZONTAL, Parameter::GUI_PARAM_WIDGETS_SPACING));
@@ -288,7 +288,7 @@ Gtk::Widget * ParamRadioButton::get_widget(SPDocument * doc, Inkscape::XML::Node
     label->show();
     hbox->pack_start(*label, false, false);
 
-    Gtk::ComboBoxText* cbt = 0;
+    Gtk::ComboBoxText* cbt = nullptr;
     bool comboSet = false;
     if (_mode == MINIMAL) {
         cbt = Gtk::manage(new ComboWdg(this, doc, node, changeSignal));
diff --git a/src/extension/param/string.cpp b/src/extension/param/string.cpp
index 51b5dfdf3..775bf62ee 100644
--- a/src/extension/param/string.cpp
+++ b/src/extension/param/string.cpp
@@ -30,7 +30,7 @@ namespace Extension {
 ParamString::~ParamString(void)
 {
     g_free(_value);
-    _value = 0;
+    _value = nullptr;
 }
 
 /**
@@ -50,11 +50,11 @@ ParamString::~ParamString(void)
  */
 const gchar * ParamString::set(const gchar * in, SPDocument * /*doc*/, Inkscape::XML::Node * /*node*/)
 {
-    if (in == NULL) {
-        return NULL; /* Can't have NULL string */
+    if (in == nullptr) {
+        return nullptr; /* Can't have NULL string */
     }
 
-    if (_value != NULL) {
+    if (_value != nullptr) {
         g_free(_value);
     }
 
@@ -84,10 +84,10 @@ ParamString::ParamString(const gchar * name,
                          Inkscape::Extension::Extension * ext,
                          Inkscape::XML::Node * xml)
     : Parameter(name, text, description, hidden, indent, ext)
-    , _value(NULL)
+    , _value(nullptr)
 {
-    const char * defaultval = NULL;
-    if (xml->firstChild() != NULL) {
+    const char * defaultval = nullptr;
+    if (xml->firstChild() != nullptr) {
         defaultval = xml->firstChild()->content();
     }
 
@@ -99,11 +99,11 @@ ParamString::ParamString(const gchar * name,
     if (!paramval.empty()) {
         defaultval = paramval.data();
     }
-    if (defaultval != NULL) {
+    if (defaultval != nullptr) {
         char const * chname = xml->name();
         if (!strcmp(chname, INKSCAPE_EXTENSION_NS "_param")) {
-            if (xml->attribute("msgctxt") != NULL) {
-                _value =  g_strdup(g_dpgettext2(NULL, xml->attribute("msgctxt"), defaultval));
+            if (xml->attribute("msgctxt") != nullptr) {
+                _value =  g_strdup(g_dpgettext2(nullptr, xml->attribute("msgctxt"), defaultval));
             } else {
                 _value = g_strdup(_(defaultval));
             }
@@ -130,8 +130,8 @@ public:
      */
     ParamStringEntry (ParamString * pref, SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal) :
         Gtk::Entry(), _pref(pref), _doc(doc), _node(node), _changeSignal(changeSignal) {
-        if (_pref->get(NULL, NULL) != NULL) {
-            this->set_text(Glib::ustring(_pref->get(NULL, NULL)));
+        if (_pref->get(nullptr, nullptr) != nullptr) {
+            this->set_text(Glib::ustring(_pref->get(nullptr, nullptr)));
         }
         this->set_max_length(_pref->getMaxLength()); //Set the max length - default zero means no maximum
         this->signal_changed().connect(sigc::mem_fun(this, &ParamStringEntry::changed_text));
@@ -150,7 +150,7 @@ void ParamStringEntry::changed_text(void)
 {
     Glib::ustring data = this->get_text();
     _pref->set(data.c_str(), _doc, _node);
-    if (_changeSignal != NULL) {
+    if (_changeSignal != nullptr) {
         _changeSignal->emit();
     }
 }
@@ -163,7 +163,7 @@ void ParamStringEntry::changed_text(void)
 Gtk::Widget * ParamString::get_widget(SPDocument * doc, Inkscape::XML::Node * node, sigc::signal<void> * changeSignal)
 {
     if (_hidden) {
-        return NULL;
+        return nullptr;
     }
 
     Gtk::HBox * hbox = Gtk::manage(new Gtk::HBox(false, Parameter::GUI_PARAM_WIDGETS_SPACING));