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

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

41 files changed, 343 insertions, 343 deletions

diff --git a/src/display/cairo-utils.cpp b/src/display/cairo-utils.cpp
index eae6b0d19..e34e4cd6b 100644
--- a/src/display/cairo-utils.cpp
+++ b/src/display/cairo-utils.cpp
@@ -162,7 +162,7 @@ Pixbuf::Pixbuf(cairo_surface_t *s)
     : _pixbuf(gdk_pixbuf_new_from_data(
         cairo_image_surface_get_data(s), GDK_COLORSPACE_RGB, TRUE, 8,
         cairo_image_surface_get_width(s), cairo_image_surface_get_height(s),
-        cairo_image_surface_get_stride(s), NULL, NULL))
+        cairo_image_surface_get_stride(s), nullptr, nullptr))
     , _surface(s)
     , _mod_time(0)
     , _pixel_format(PF_CAIRO)
@@ -174,7 +174,7 @@ Pixbuf::Pixbuf(cairo_surface_t *s)
  * so it should not be unrefed. */
 Pixbuf::Pixbuf(GdkPixbuf *pb)
     : _pixbuf(pb)
-    , _surface(0)
+    , _surface(nullptr)
     , _mod_time(0)
     , _pixel_format(PF_GDK)
     , _cairo_store(false)
@@ -209,7 +209,7 @@ Pixbuf::~Pixbuf()
 
 Pixbuf *Pixbuf::create_from_data_uri(gchar const *uri_data)
 {
-    Pixbuf *pixbuf = NULL;
+    Pixbuf *pixbuf = nullptr;
 
     bool data_is_image = false;
     bool data_is_svg = false;
@@ -271,13 +271,13 @@ Pixbuf *Pixbuf::create_from_data_uri(gchar const *uri_data)
     if ((*data) && data_is_image && !data_is_svg && data_is_base64) {
         GdkPixbufLoader *loader = gdk_pixbuf_loader_new();
 
-        if (!loader) return NULL;
+        if (!loader) return nullptr;
 
         gsize decoded_len = 0;
         guchar *decoded = g_base64_decode(data, &decoded_len);
 
-        if (gdk_pixbuf_loader_write(loader, decoded, decoded_len, NULL)) {
-            gdk_pixbuf_loader_close(loader, NULL);
+        if (gdk_pixbuf_loader_write(loader, decoded, decoded_len, nullptr)) {
+            gdk_pixbuf_loader_close(loader, nullptr);
             GdkPixbuf *buf = gdk_pixbuf_loader_get_pixbuf(loader);
             if (buf) {
                 g_object_ref(buf);
@@ -301,13 +301,13 @@ Pixbuf *Pixbuf::create_from_data_uri(gchar const *uri_data)
         guchar *decoded = g_base64_decode(data, &decoded_len);
         SPDocument *svgDoc = SPDocument::createNewDocFromMem (reinterpret_cast<gchar const *>(decoded), decoded_len, false);
         // Check the document loaded properly
-        if (svgDoc == NULL) {
-            return NULL;
+        if (svgDoc == nullptr) {
+            return nullptr;
         }
-        if (svgDoc->getRoot() == NULL)
+        if (svgDoc->getRoot() == nullptr)
         {
             svgDoc->doUnref();
-            return NULL;
+            return nullptr;
         }
         Inkscape::Preferences *prefs = Inkscape::Preferences::get();
         const double dpi = prefs->getDouble("/dialogs/import/defaultxdpi/value", 96.0);
@@ -321,13 +321,13 @@ Pixbuf *Pixbuf::create_from_data_uri(gchar const *uri_data)
         const int scaledSvgWidth  = round(svgWidth_px/(96.0/dpi));
         const int scaledSvgHeight = round(svgHeight_px/(96.0/dpi));
 
-        GdkPixbuf *buf = sp_generate_internal_bitmap(svgDoc, NULL, 0, 0, svgWidth_px, svgHeight_px, scaledSvgWidth, scaledSvgHeight, dpi, dpi, (guint32) 0xffffff00, NULL)->getPixbufRaw();
+        GdkPixbuf *buf = sp_generate_internal_bitmap(svgDoc, nullptr, 0, 0, svgWidth_px, svgHeight_px, scaledSvgWidth, scaledSvgHeight, dpi, dpi, (guint32) 0xffffff00, nullptr)->getPixbufRaw();
         // Tidy up
         svgDoc->doUnref();
-        if (buf == NULL) {
+        if (buf == nullptr) {
             std::cerr << "Pixbuf::create_from_data: failed to load contents: " << std::endl;
             g_free(decoded);
-            return NULL;
+            return nullptr;
         } else {
             g_object_ref(buf);
             pixbuf = new Pixbuf(buf);
@@ -340,32 +340,32 @@ Pixbuf *Pixbuf::create_from_data_uri(gchar const *uri_data)
 
 Pixbuf *Pixbuf::create_from_file(std::string const &fn)
 {
-    Pixbuf *pb = NULL;
+    Pixbuf *pb = nullptr;
     // test correctness of filename
     if (!g_file_test(fn.c_str(), G_FILE_TEST_EXISTS)) { 
-        return NULL;
+        return nullptr;
     }
     GStatBuf stdir;
     int val = g_stat(fn.c_str(), &stdir);
     if (val == 0 && stdir.st_mode & S_IFDIR){
-        return NULL;
+        return nullptr;
     }
 
     // we need to load the entire file into memory,
     // since we'll store it as MIME data
-    gchar *data = NULL;
+    gchar *data = nullptr;
     gsize len = 0;
-    GError *error = NULL;
+    GError *error = nullptr;
 
     if (g_file_get_contents(fn.c_str(), &data, &len, &error)) {
 
-        if (error != NULL) {
+        if (error != nullptr) {
             std::cerr << "Pixbuf::create_from_file: " << error->message << std::endl;
             std::cerr << "   (" << fn << ")" << std::endl;
-            return NULL;
+            return nullptr;
         }
-        GdkPixbuf *buf = NULL;
-        GdkPixbufLoader *loader = NULL;
+        GdkPixbuf *buf = nullptr;
+        GdkPixbufLoader *loader = nullptr;
         std::string::size_type idx;
         idx = fn.rfind('.');
         bool is_svg = false;    
@@ -374,13 +374,13 @@ Pixbuf *Pixbuf::create_from_file(std::string const &fn)
             if (boost::iequals(fn.substr(idx+1).c_str(), "svg")) {
                 SPDocument *svgDoc = SPDocument::createNewDoc(fn.c_str(), TRUE);
                // Check the document loaded properly
-                if (svgDoc == NULL) {
-                    return NULL;
+                if (svgDoc == nullptr) {
+                    return nullptr;
                 }
-                if (svgDoc->getRoot() == NULL)
+                if (svgDoc->getRoot() == nullptr)
                 {
                     svgDoc->doUnref();
-                    return NULL;
+                    return nullptr;
                 }
                 Inkscape::Preferences *prefs = Inkscape::Preferences::get();
                 const double dpi = prefs->getDouble("/dialogs/import/defaultxdpi/value", 96.0);
@@ -394,12 +394,12 @@ Pixbuf *Pixbuf::create_from_file(std::string const &fn)
                 const int scaledSvgWidth  = round(svgWidth_px/(96.0/dpi));
                 const int scaledSvgHeight = round(svgHeight_px/(96.0/dpi));
 
-                buf = sp_generate_internal_bitmap(svgDoc, NULL, 0, 0, svgWidth_px, svgHeight_px, scaledSvgWidth, scaledSvgHeight, dpi, dpi, (guint32) 0xffffff00, NULL)->getPixbufRaw();
+                buf = sp_generate_internal_bitmap(svgDoc, nullptr, 0, 0, svgWidth_px, svgHeight_px, scaledSvgWidth, scaledSvgHeight, dpi, dpi, (guint32) 0xffffff00, nullptr)->getPixbufRaw();
 
                 // Tidy up
                 svgDoc->doUnref();
-                if (buf == NULL) {
-                    return NULL;
+                if (buf == nullptr) {
+                    return nullptr;
                 }
                 is_svg = true;
             }
@@ -407,21 +407,21 @@ Pixbuf *Pixbuf::create_from_file(std::string const &fn)
         if (!is_svg) {
             loader = gdk_pixbuf_loader_new();
             gdk_pixbuf_loader_write(loader, (guchar *) data, len, &error);
-            if (error != NULL) {
+            if (error != nullptr) {
                 std::cerr << "Pixbuf::create_from_file: " << error->message << std::endl;
                 std::cerr << "   (" << fn << ")" << std::endl;
                 g_free(data);
                 g_object_unref(loader);
-                return NULL;
+                return nullptr;
             }
 
             gdk_pixbuf_loader_close(loader, &error);
-            if (error != NULL) {
+            if (error != nullptr) {
                 std::cerr << "Pixbuf::create_from_file: " << error->message << std::endl;
                 std::cerr << "   (" << fn << ")" << std::endl;
                 g_free(data);
                 g_object_unref(loader);
-                return NULL;
+                return nullptr;
             }
             
             buf = gdk_pixbuf_loader_get_pixbuf(loader);
@@ -449,7 +449,7 @@ Pixbuf *Pixbuf::create_from_file(std::string const &fn)
         // from the file. This can be done by using format-specific libraries e.g. libpng.
     } else {
         std::cerr << "Pixbuf::create_from_file: failed to get contents: " << fn << std::endl;
-        return NULL;
+        return nullptr;
     }
 
     return pb;
@@ -512,15 +512,15 @@ Cairo::RefPtr<Cairo::Surface> Pixbuf::getSurface(bool convert_format)
 guchar const *Pixbuf::getMimeData(gsize &len, std::string &mimetype) const
 {
     static gchar const *mimetypes[] = {
-        CAIRO_MIME_TYPE_JPEG, CAIRO_MIME_TYPE_JP2, CAIRO_MIME_TYPE_PNG, NULL };
+        CAIRO_MIME_TYPE_JPEG, CAIRO_MIME_TYPE_JP2, CAIRO_MIME_TYPE_PNG, nullptr };
     static guint mimetypes_len = g_strv_length(const_cast<gchar**>(mimetypes));
 
-    guchar const *data = NULL;
+    guchar const *data = nullptr;
 
     for (guint i = 0; i < mimetypes_len; ++i) {
         unsigned long len_long = 0;
         cairo_surface_get_mime_data(const_cast<cairo_surface_t*>(_surface), mimetypes[i], &data, &len_long);
-        if (data != NULL) {
+        if (data != nullptr) {
 			len = len_long;
             mimetype = mimetypes[i];
             break;
@@ -560,7 +560,7 @@ void Pixbuf::_forceAlpha()
 
 void Pixbuf::_setMimeData(guchar *data, gsize len, Glib::ustring const &format)
 {
-    gchar const *mimetype = NULL;
+    gchar const *mimetype = nullptr;
 
     if (format == "jpeg") {
         mimetype = CAIRO_MIME_TYPE_JPEG;
@@ -570,7 +570,7 @@ void Pixbuf::_setMimeData(guchar *data, gsize len, Glib::ustring const &format)
         mimetype = CAIRO_MIME_TYPE_PNG;
     }
 
-    if (mimetype != NULL) {
+    if (mimetype != nullptr) {
         cairo_surface_set_mime_data(_surface, mimetype, data, len, g_free, data);
         //g_message("Setting Cairo MIME data: %s", mimetype);
     } else {
@@ -837,7 +837,7 @@ feed_pathvector_to_cairo (cairo_t *ct, Geom::PathVector const &pathv)
 SPColorInterpolation
 get_cairo_surface_ci(cairo_surface_t *surface) {
     void* data = cairo_surface_get_user_data( surface, &ink_color_interpolation_key );
-    if( data != NULL ) {
+    if( data != nullptr ) {
         return (SPColorInterpolation)GPOINTER_TO_INT( data );
     } else {
         return SP_CSS_COLOR_INTERPOLATION_AUTO;
@@ -862,13 +862,13 @@ set_cairo_surface_ci(cairo_surface_t *surface, SPColorInterpolation ci) {
             ink_cairo_surface_linear_to_srgb( surface );
         }
 
-        cairo_surface_set_user_data(surface, &ink_color_interpolation_key, GINT_TO_POINTER (ci), NULL);
+        cairo_surface_set_user_data(surface, &ink_color_interpolation_key, GINT_TO_POINTER (ci), nullptr);
     }
 }
 
 void
 copy_cairo_surface_ci(cairo_surface_t *in, cairo_surface_t *out) {
-    cairo_surface_set_user_data(out, &ink_color_interpolation_key, cairo_surface_get_user_data(in, &ink_color_interpolation_key), NULL);
+    cairo_surface_set_user_data(out, &ink_color_interpolation_key, cairo_surface_get_user_data(in, &ink_color_interpolation_key), nullptr);
 }
 
 void
@@ -957,7 +957,7 @@ cairo_surface_t *
 ink_cairo_surface_create_identical(cairo_surface_t *s)
 {
     cairo_surface_t *ns = ink_cairo_surface_create_same_size(s, cairo_surface_get_content(s));
-    cairo_surface_set_user_data(ns, &ink_color_interpolation_key, cairo_surface_get_user_data(s, &ink_color_interpolation_key), NULL);
+    cairo_surface_set_user_data(ns, &ink_color_interpolation_key, cairo_surface_get_user_data(s, &ink_color_interpolation_key), nullptr);
     return ns;
 }
 
@@ -1004,7 +1004,7 @@ ink_cairo_surface_create_output(cairo_surface_t *image, cairo_surface_t *bg)
 {
     cairo_content_t imgt = cairo_surface_get_content(image);
     cairo_content_t bgt = cairo_surface_get_content(bg);
-    cairo_surface_t *out = NULL;
+    cairo_surface_t *out = nullptr;
 
     if (bgt == CAIRO_CONTENT_ALPHA && imgt == CAIRO_CONTENT_ALPHA) {
         out = ink_cairo_surface_create_identical(bg);
@@ -1416,7 +1416,7 @@ void
 ink_pixbuf_ensure_argb32(GdkPixbuf *pb)
 {
     gchar *pixel_format = reinterpret_cast<gchar*>(g_object_get_data(G_OBJECT(pb), "pixel_format"));
-    if (pixel_format != NULL && strcmp(pixel_format, "argb32") == 0) {
+    if (pixel_format != nullptr && strcmp(pixel_format, "argb32") == 0) {
         // nothing to do
         return;
     }
@@ -1437,7 +1437,7 @@ void
 ink_pixbuf_ensure_normal(GdkPixbuf *pb)
 {
     gchar *pixel_format = reinterpret_cast<gchar*>(g_object_get_data(G_OBJECT(pb), "pixel_format"));
-    if (pixel_format == NULL || strcmp(pixel_format, "pixbuf") == 0) {
+    if (pixel_format == nullptr || strcmp(pixel_format, "pixbuf") == 0) {
         // nothing to do
         return;
     }
diff --git a/src/display/canvas-arena.cpp b/src/display/canvas-arena.cpp
index 8271a6ad9..72415d82d 100644
--- a/src/display/canvas-arena.cpp
+++ b/src/display/canvas-arena.cpp
@@ -78,7 +78,7 @@ sp_canvas_arena_class_init (SPCanvasArenaClass *klass)
                                            G_TYPE_FROM_CLASS(item_class),
                                            G_SIGNAL_RUN_LAST,
                                            ((glong)((guint8*)&(klass->arena_event) - (guint8*)klass)),
-					   NULL, NULL,
+					   nullptr, nullptr,
                                            sp_marshal_INT__POINTER_POINTER,
                                            G_TYPE_INT, 2, G_TYPE_POINTER, G_TYPE_POINTER);
 
@@ -116,7 +116,7 @@ sp_canvas_arena_init (SPCanvasArena *arena)
             sigc::ptr_fun(&sp_canvas_arena_item_deleted),
             arena));
 
-    arena->active = NULL;
+    arena->active = nullptr;
 }
 
 static void sp_canvas_arena_destroy(SPCanvasItem *object)
@@ -180,7 +180,7 @@ static void
 sp_canvas_arena_item_deleted(SPCanvasArena *arena, Inkscape::DrawingItem *item)
 {
     if (arena->active == item) {
-        arena->active = NULL;
+        arena->active = nullptr;
     }
 }
 
@@ -260,7 +260,7 @@ sp_canvas_arena_event (SPCanvasItem *item, GdkEvent *event)
         case GDK_LEAVE_NOTIFY:
             if (arena->cursor) {
                 ret = sp_canvas_arena_send_event (arena, event);
-                arena->active = NULL;
+                arena->active = nullptr;
                 arena->cursor = FALSE;
             }
             break;
@@ -342,7 +342,7 @@ static void sp_canvas_arena_request_render(SPCanvasArena *ca, Geom::IntRect cons
 void
 sp_canvas_arena_set_pick_delta (SPCanvasArena *ca, gdouble delta)
 {
-    g_return_if_fail (ca != NULL);
+    g_return_if_fail (ca != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ARENA (ca));
 
     /* fixme: repick? */
@@ -352,7 +352,7 @@ sp_canvas_arena_set_pick_delta (SPCanvasArena *ca, gdouble delta)
 void
 sp_canvas_arena_set_sticky (SPCanvasArena *ca, gboolean sticky)
 {
-    g_return_if_fail (ca != NULL);
+    g_return_if_fail (ca != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ARENA (ca));
 
     /* fixme: repick? */
@@ -362,7 +362,7 @@ sp_canvas_arena_set_sticky (SPCanvasArena *ca, gboolean sticky)
 void
 sp_canvas_arena_render_surface (SPCanvasArena *ca, cairo_surface_t *surface, Geom::IntRect const &r)
 {
-    g_return_if_fail (ca != NULL);
+    g_return_if_fail (ca != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ARENA (ca));
 
     Inkscape::DrawingContext dc(surface, r.min());
diff --git a/src/display/canvas-axonomgrid.cpp b/src/display/canvas-axonomgrid.cpp
index 66231b7dd..8d9cb7d0a 100644
--- a/src/display/canvas-axonomgrid.cpp
+++ b/src/display/canvas-axonomgrid.cpp
@@ -191,7 +191,7 @@ CanvasAxonomGrid::readRepr()
     }
 
     if ( (value = repr->attribute("gridanglex")) ) {
-        angle_deg[X] = g_ascii_strtod(value, NULL);
+        angle_deg[X] = g_ascii_strtod(value, nullptr);
         if (angle_deg[X] < 0.) angle_deg[X] = 0.;
         if (angle_deg[X] > 89.0) angle_deg[X] = 89.0;
         angle_rad[X] = Geom::rad_from_deg(angle_deg[X]);
@@ -199,7 +199,7 @@ CanvasAxonomGrid::readRepr()
     }
 
     if ( (value = repr->attribute("gridanglez")) ) {
-        angle_deg[Z] = g_ascii_strtod(value, NULL);
+        angle_deg[Z] = g_ascii_strtod(value, nullptr);
         if (angle_deg[Z] < 0.) angle_deg[Z] = 0.;
         if (angle_deg[Z] > 89.0) angle_deg[Z] = 89.0;
         angle_rad[Z] = Geom::rad_from_deg(angle_deg[Z]);
@@ -230,12 +230,12 @@ CanvasAxonomGrid::readRepr()
     }
 
     if ( (value = repr->attribute("enabled")) ) {
-        g_assert(snapper != NULL);
+        g_assert(snapper != nullptr);
         snapper->setEnabled(strcmp(value,"false") != 0 && strcmp(value, "0") != 0);
     }
 
     if ( (value = repr->attribute("snapvisiblegridlinesonly")) ) {
-        g_assert(snapper != NULL);
+        g_assert(snapper != nullptr);
         snapper->setSnapVisibleOnly(strcmp(value,"false") != 0 && strcmp(value, "0") != 0);
     }
 
@@ -358,7 +358,7 @@ CanvasAxonomGrid::updateWidgets()
     _wr.setUpdating (true);
 
     _rcb_visible->setActive(visible);
-    if (snapper != NULL) {
+    if (snapper != nullptr) {
         _rcb_enabled->setActive(snapper->getEnabled());
         _rcb_snap_visible_only->setActive(snapper->getSnapVisibleOnly());
     }
@@ -590,7 +590,7 @@ CanvasAxonomGridSnapper::_getSnapLines(Geom::Point const &p) const
 {
     LineList s;
 
-    if ( grid == NULL ) {
+    if ( grid == nullptr ) {
         return s;
     }
 
diff --git a/src/display/canvas-bpath.cpp b/src/display/canvas-bpath.cpp
index fc6b79b43..35f46e2ae 100644
--- a/src/display/canvas-bpath.cpp
+++ b/src/display/canvas-bpath.cpp
@@ -172,7 +172,7 @@ sp_canvas_bpath_point (SPCanvasItem *item, Geom::Point p, SPCanvasItem **actual_
     Geom::Rect viewbox = item->canvas->getViewbox();
     viewbox.expandBy (width);
     double dist = Geom::infinity();
-    pathv_matrix_point_bbox_wind_distance(cbp->curve->get_pathvector(), cbp->affine, p, NULL, NULL, &dist, 0.5, &viewbox);
+    pathv_matrix_point_bbox_wind_distance(cbp->curve->get_pathvector(), cbp->affine, p, nullptr, nullptr, &dist, 0.5, &viewbox);
 
     if (dist <= 1.0) {
         *actual_item = item;
@@ -184,10 +184,10 @@ sp_canvas_bpath_point (SPCanvasItem *item, Geom::Point p, SPCanvasItem **actual_
 SPCanvasItem *
 sp_canvas_bpath_new (SPCanvasGroup *parent, SPCurve *curve, bool phantom_line)
 {
-    g_return_val_if_fail (parent != NULL, NULL);
+    g_return_val_if_fail (parent != nullptr, NULL);
     g_return_val_if_fail (SP_IS_CANVAS_GROUP (parent), NULL);
 
-    SPCanvasItem *item = sp_canvas_item_new (parent, SP_TYPE_CANVAS_BPATH, NULL);
+    SPCanvasItem *item = sp_canvas_item_new (parent, SP_TYPE_CANVAS_BPATH, nullptr);
 
     sp_canvas_bpath_set_bpath (SP_CANVAS_BPATH (item), curve, phantom_line);
 
@@ -197,7 +197,7 @@ sp_canvas_bpath_new (SPCanvasGroup *parent, SPCurve *curve, bool phantom_line)
 void
 sp_canvas_bpath_set_bpath (SPCanvasBPath *cbp, SPCurve *curve, bool phantom_line)
 {
-    g_return_if_fail (cbp != NULL);
+    g_return_if_fail (cbp != nullptr);
     g_return_if_fail (SP_IS_CANVAS_BPATH (cbp));
 
     cbp->phantom_line = phantom_line;
@@ -215,7 +215,7 @@ sp_canvas_bpath_set_bpath (SPCanvasBPath *cbp, SPCurve *curve, bool phantom_line
 void
 sp_canvas_bpath_set_fill (SPCanvasBPath *cbp, guint32 rgba, SPWindRule rule)
 {
-    g_return_if_fail (cbp != NULL);
+    g_return_if_fail (cbp != nullptr);
     g_return_if_fail (SP_IS_CANVAS_BPATH (cbp));
 
     cbp->fill_rgba = rgba;
@@ -227,7 +227,7 @@ sp_canvas_bpath_set_fill (SPCanvasBPath *cbp, guint32 rgba, SPWindRule rule)
 void
 sp_canvas_bpath_set_stroke (SPCanvasBPath *cbp, guint32 rgba, gdouble width, SPStrokeJoinType join, SPStrokeCapType cap, double dash, double gap)
 {
-    g_return_if_fail (cbp != NULL);
+    g_return_if_fail (cbp != nullptr);
     g_return_if_fail (SP_IS_CANVAS_BPATH (cbp));
 
     cbp->stroke_rgba = rgba;
diff --git a/src/display/canvas-debug.cpp b/src/display/canvas-debug.cpp
index 00a4f3fee..a4ca19673 100644
--- a/src/display/canvas-debug.cpp
+++ b/src/display/canvas-debug.cpp
@@ -41,7 +41,7 @@ static void sp_canvas_debug_init (SPCanvasDebug *debug)
 namespace {
 static void sp_canvas_debug_destroy (SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_CANVAS_DEBUG (object));
 
     if (SP_CANVAS_ITEM_CLASS(sp_canvas_debug_parent_class)->destroy) {
diff --git a/src/display/canvas-grid.cpp b/src/display/canvas-grid.cpp
index 6d646f39d..42769e1b1 100644
--- a/src/display/canvas-grid.cpp
+++ b/src/display/canvas-grid.cpp
@@ -81,12 +81,12 @@ static void grid_canvasitem_class_init(GridCanvasItemClass *klass)
 static void
 grid_canvasitem_init (GridCanvasItem *griditem)
 {
-    griditem->grid = NULL;
+    griditem->grid = nullptr;
 }
 
 static void grid_canvasitem_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (INKSCAPE_IS_GRID_CANVASITEM (object));
 
     if (SP_CANVAS_ITEM_CLASS(grid_canvasitem_parent_class)->destroy)
@@ -131,11 +131,11 @@ grid_canvasitem_update (SPCanvasItem *item, Geom::Affine const &affine, unsigned
 //   CanvasGrid
 
     static Inkscape::XML::NodeEventVector const _repr_events = {
-        NULL, /* child_added */
-        NULL, /* child_removed */
+        nullptr, /* child_added */
+        nullptr, /* child_removed */
         CanvasGrid::on_repr_attr_changed,
-        NULL, /* content_changed */
-        NULL  /* order_changed */
+        nullptr, /* content_changed */
+        nullptr  /* order_changed */
     };
 
 CanvasGrid::CanvasGrid(SPNamedView * nv, Inkscape::XML::Node * in_repr, SPDocument *in_doc, GridType type)
@@ -244,10 +244,10 @@ CanvasGrid::writeNewGridToRepr(Inkscape::XML::Node * repr, SPDocument * doc, Gri
 CanvasGrid*
 CanvasGrid::NewGrid(SPNamedView * nv, Inkscape::XML::Node * repr, SPDocument * doc, GridType gridtype)
 {
-    if (!repr) return NULL;
+    if (!repr) return nullptr;
     if (!doc) {
         g_error("CanvasGrid::NewGrid - doc==NULL");
-        return NULL;
+        return nullptr;
     }
 
     switch (gridtype) {
@@ -257,7 +257,7 @@ CanvasGrid::NewGrid(SPNamedView * nv, Inkscape::XML::Node * repr, SPDocument * d
             return dynamic_cast<CanvasGrid*>(new CanvasAxonomGrid(nv, repr, doc));
     }
 
-    return NULL;
+    return nullptr;
 }
 
 
@@ -267,18 +267,18 @@ CanvasGrid::NewGrid(SPNamedView * nv, Inkscape::XML::Node * repr, SPDocument * d
 GridCanvasItem *
 CanvasGrid::createCanvasItem(SPDesktop * desktop)
 {
-    if (!desktop) return NULL;
+    if (!desktop) return nullptr;
 //    Johan: I think for multiple desktops it is best if each has their own canvasitem,
 //           but share the same CanvasGrid object; that is what this function is for.
 
     // check if there is already a canvasitem on this desktop linking to this grid
     for (auto i:canvasitems) {
         if ( desktop->getGridGroup() == SP_CANVAS_GROUP(i->parent) ) {
-            return NULL;
+            return nullptr;
         }
     }
 
-    GridCanvasItem * item = INKSCAPE_GRID_CANVASITEM( sp_canvas_item_new(desktop->getGridGroup(), INKSCAPE_TYPE_GRID_CANVASITEM, NULL) );
+    GridCanvasItem * item = INKSCAPE_GRID_CANVASITEM( sp_canvas_item_new(desktop->getGridGroup(), INKSCAPE_TYPE_GRID_CANVASITEM, nullptr) );
     item->grid = this;
     sp_canvas_item_show(SP_CANVAS_ITEM(item));
 
@@ -340,7 +340,7 @@ CanvasGrid::newWidget()
     // set widget values
     _wr.setUpdating (true);
     _rcb_visible->setActive(visible);
-    if (snapper != NULL) {
+    if (snapper != nullptr) {
         _rcb_enabled->setActive(snapper->getEnabled());
         _rcb_snap_visible_only->setActive(snapper->getSnapVisibleOnly());
     }
@@ -359,7 +359,7 @@ CanvasGrid::on_repr_attr_changed(Inkscape::XML::Node *repr, gchar const *key, gc
 
 bool CanvasGrid::isEnabled() const
 {
-    if (snapper == NULL) {
+    if (snapper == nullptr) {
        return false;
     }
 
@@ -454,7 +454,7 @@ static void validateInt(gint oldVal,
                         gint* pTarget)
 {
     // Avoid nullness.
-    if ( pTarget == NULL )
+    if ( pTarget == nullptr )
         return;
 
     // Invalid new value?
@@ -600,12 +600,12 @@ CanvasXYGrid::readRepr()
     }
 
     if ( (value = repr->attribute("enabled")) ) {
-        g_assert(snapper != NULL);
+        g_assert(snapper != nullptr);
         snapper->setEnabled(strcmp(value,"false") != 0 && strcmp(value, "0") != 0);
     }
 
     if ( (value = repr->attribute("snapvisiblegridlinesonly")) ) {
-        g_assert(snapper != NULL);
+        g_assert(snapper != nullptr);
         snapper->setSnapVisibleOnly(strcmp(value,"false") != 0 && strcmp(value, "0") != 0);
     }
 
@@ -735,7 +735,7 @@ CanvasXYGrid::updateWidgets()
     _wr.setUpdating (true);
 
     _rcb_visible->setActive(visible);
-    if (snapper != NULL) {
+    if (snapper != nullptr) {
         _rcb_enabled->setActive(snapper->getEnabled());
         _rcb_snap_visible_only->setActive(snapper->getSnapVisibleOnly());
     }
@@ -1022,7 +1022,7 @@ CanvasXYGridSnapper::_getSnapLines(Geom::Point const &p) const
 {
     LineList s;
 
-    if ( grid == NULL ) {
+    if ( grid == nullptr ) {
         return s;
     }
 
diff --git a/src/display/canvas-rotate.cpp b/src/display/canvas-rotate.cpp
index 1d917a677..61728ca50 100644
--- a/src/display/canvas-rotate.cpp
+++ b/src/display/canvas-rotate.cpp
@@ -48,14 +48,14 @@ static void sp_canvas_rotate_init (SPCanvasRotate *rotate)
     rotate->pickable = true; // So we can receive events.
     rotate->angle = 0.0;
     rotate->start_angle = -1000;
-    rotate->surface_copy = NULL;
-    rotate->surface_rotated = NULL;
+    rotate->surface_copy = nullptr;
+    rotate->surface_rotated = nullptr;
 }
 
 namespace {
 static void sp_canvas_rotate_destroy (SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ROTATE (object));
 
     if (SP_CANVAS_ITEM_CLASS(sp_canvas_rotate_parent_class)->destroy) {
@@ -68,15 +68,15 @@ static void sp_canvas_rotate_update( SPCanvasItem *item, Geom::Affine const &/*a
 {
     SPCanvasRotate *cr = SP_CANVAS_ROTATE(item);
 
-    if (cr->surface_copy == NULL) {
+    if (cr->surface_copy == nullptr) {
         // std::cout << "sp_canvas_rotate_update: surface_copy is NULL" << std::endl;
         return;
     }
 
     // Destroy surface_rotated if it already exists.
-    if (cr->surface_rotated != NULL) {
+    if (cr->surface_rotated != nullptr) {
         cairo_surface_destroy (cr->surface_rotated);
-        cr->surface_rotated = NULL;
+        cr->surface_rotated = nullptr;
     }
 
     // Create rotated surface
@@ -114,7 +114,7 @@ static void sp_canvas_rotate_render( SPCanvasItem *item, SPCanvasBuf *buf)
         return;
     }
 
-    if (cr->surface_rotated == NULL ) {
+    if (cr->surface_rotated == nullptr ) {
         // std::cout << "  surface_rotated is NULL" << std::endl;
         return;
     }
@@ -206,13 +206,13 @@ static int sp_canvas_rotate_event  (SPCanvasItem *item, GdkEvent *event)
             sp_canvas_item_hide (item);
 
             cr->start_angle = -1000;
-            if (cr->surface_copy != NULL) {
+            if (cr->surface_copy != nullptr) {
                 cairo_surface_destroy( cr->surface_copy );
-                cr->surface_copy = NULL;
+                cr->surface_copy = nullptr;
             }
-            if (cr->surface_rotated != NULL) {
+            if (cr->surface_rotated != nullptr) {
                 cairo_surface_destroy( cr->surface_rotated );
-                cr->surface_rotated = NULL;
+                cr->surface_rotated = nullptr;
             }
             // sp_canvas_item_show (desktop->drawing);
 
@@ -237,7 +237,7 @@ static int sp_canvas_rotate_event  (SPCanvasItem *item, GdkEvent *event)
 
 void sp_canvas_rotate_start (SPCanvasRotate *canvas_rotate, cairo_surface_t *background)
 {
-    if (background == NULL) {
+    if (background == nullptr) {
         std::cerr << "sp_canvas_rotate_start: background is NULL!" << std::endl;
         return;
     }
@@ -254,7 +254,7 @@ void sp_canvas_rotate_start (SPCanvasRotate *canvas_rotate, cairo_surface_t *bac
 // Paint the canvas ourselves for speed....
 void sp_canvas_rotate_paint (SPCanvasRotate *canvas_rotate, cairo_surface_t *background)
 {
-    if (background == NULL) {
+    if (background == nullptr) {
         std::cerr << "sp_canvas_rotate_paint: background is NULL!" << std::endl;
         return;
     }
diff --git a/src/display/canvas-text.cpp b/src/display/canvas-text.cpp
index 4117825e3..9df002f7f 100644
--- a/src/display/canvas-text.cpp
+++ b/src/display/canvas-text.cpp
@@ -52,9 +52,9 @@ sp_canvastext_init (SPCanvasText *canvastext)
     canvastext->s[Geom::X] = canvastext->s[Geom::Y] = 0.0;
     canvastext->affine = Geom::identity();
     canvastext->fontsize = 10.0;
-    canvastext->item = NULL;
-    canvastext->desktop = NULL;
-    canvastext->text = NULL;
+    canvastext->item = nullptr;
+    canvastext->desktop = nullptr;
+    canvastext->text = nullptr;
     canvastext->outline = false;
     canvastext->background = false;
     canvastext->border = 3; // must be a constant, and not proportional to any width, height, or fontsize to allow alignment with other text boxes
@@ -62,14 +62,14 @@ sp_canvastext_init (SPCanvasText *canvastext)
 
 static void sp_canvastext_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_CANVASTEXT (object));
 
     SPCanvasText *canvastext = SP_CANVASTEXT (object);
 
     g_free(canvastext->text);
-    canvastext->text = NULL;
-    canvastext->item = NULL;
+    canvastext->text = nullptr;
+    canvastext->item = nullptr;
 
     if (SP_CANVAS_ITEM_CLASS(sp_canvastext_parent_class)->destroy)
         SP_CANVAS_ITEM_CLASS(sp_canvastext_parent_class)->destroy(object);
@@ -227,7 +227,7 @@ SPCanvasText *sp_canvastext_new(SPCanvasGroup *parent, SPDesktop *desktop, Geom:
 {
     // Pos specifies the position of the anchor, which is at the bounding box of the text itself (i.e. not at the border of the filled background rectangle)
     // The relative position of the anchor can be set using e.g. anchor_position = TEXT_ANCHOR_LEFT
-    SPCanvasItem *item = sp_canvas_item_new(parent, SP_TYPE_CANVASTEXT, NULL);
+    SPCanvasItem *item = sp_canvas_item_new(parent, SP_TYPE_CANVASTEXT, nullptr);
 
     SPCanvasText *ct = SP_CANVASTEXT(item);
 
@@ -244,7 +244,7 @@ SPCanvasText *sp_canvastext_new(SPCanvasGroup *parent, SPDesktop *desktop, Geom:
 void
 sp_canvastext_set_rgba32 (SPCanvasText *ct, guint32 rgba, guint32 rgba_stroke)
 {
-    g_return_if_fail (ct != NULL);
+    g_return_if_fail (ct != nullptr);
     g_return_if_fail (SP_IS_CANVASTEXT (ct));
 
     if (rgba != ct->rgba || rgba_stroke != ct->rgba_stroke) {
diff --git a/src/display/curve.cpp b/src/display/curve.cpp
index 1115978e9..e424fee05 100644
--- a/src/display/curve.cpp
+++ b/src/display/curve.cpp
@@ -127,7 +127,7 @@ SPCurve::unref()
         delete this;
     }
 
-    return NULL;
+    return nullptr;
 }
 
 /**
@@ -341,7 +341,7 @@ SPCurve::is_closed() const
 bool
 SPCurve::is_equal(SPCurve * other) const
 {
-    if(other == NULL) {
+    if(other == nullptr) {
         return false;
     } else if(_pathv == other->get_pathvector()){
         return true;
@@ -357,10 +357,10 @@ Geom::Curve const *
 SPCurve::last_segment() const
 {
     if (is_empty()) {
-        return NULL;
+        return nullptr;
     }
     if (_pathv.back().empty()) {
-        return NULL;
+        return nullptr;
     }
 
     return &_pathv.back().back_default();
@@ -373,7 +373,7 @@ Geom::Path const *
 SPCurve::last_path() const
 {
     if (is_empty()) {
-        return NULL;
+        return nullptr;
     }
 
     return &_pathv.back();
@@ -387,10 +387,10 @@ Geom::Curve const *
 SPCurve::first_segment() const
 {
     if (is_empty()) {
-        return NULL;
+        return nullptr;
     }
     if (_pathv.front().empty()) {
-        return NULL;
+        return nullptr;
     }
 
     return &_pathv.front().front();
@@ -403,7 +403,7 @@ Geom::Path const *
 SPCurve::first_path() const
 {
     if (is_empty()) {
-        return NULL;
+        return nullptr;
     }
 
     return &_pathv.front();
@@ -545,9 +545,9 @@ SPCurve::append_continuous(SPCurve const *c1, double tolerance)
     using Geom::X;
     using Geom::Y;
 
-    g_return_val_if_fail(c1 != NULL, NULL);
+    g_return_val_if_fail(c1 != nullptr, NULL);
     if ( this->is_closed() || c1->is_closed() ) {
-        return NULL;
+        return nullptr;
     }
 
     if (c1->is_empty()) {
diff --git a/src/display/drawing-context.cpp b/src/display/drawing-context.cpp
index ffd60ef9f..16263b607 100644
--- a/src/display/drawing-context.cpp
+++ b/src/display/drawing-context.cpp
@@ -24,7 +24,7 @@ using Geom::Y;
  */
 
 DrawingContext::Save::Save()
-    : _dc(NULL)
+    : _dc(nullptr)
 {}
 DrawingContext::Save::Save(DrawingContext &dc)
     : _dc(&dc)
@@ -70,7 +70,7 @@ DrawingContext::DrawingContext(cairo_t *ct, Geom::Point const &origin)
 }
 
 DrawingContext::DrawingContext(cairo_surface_t *surface, Geom::Point const &origin)
-    : _ct(NULL)
+    : _ct(nullptr)
     , _surface(new DrawingSurface(surface, origin))
     , _delete_surface(true)
     , _restore_context(false)
diff --git a/src/display/drawing-group.cpp b/src/display/drawing-group.cpp
index 6abce34a2..22a6c42ed 100644
--- a/src/display/drawing-group.cpp
+++ b/src/display/drawing-group.cpp
@@ -18,7 +18,7 @@ namespace Inkscape {
 
 DrawingGroup::DrawingGroup(Drawing &drawing)
     : DrawingItem(drawing)
-    , _child_transform(NULL)
+    , _child_transform(nullptr)
 {}
 
 DrawingGroup::~DrawingGroup()
@@ -54,7 +54,7 @@ DrawingGroup::setChildTransform(Geom::Affine const &new_trans)
         _markForRendering();
         if (new_trans.isIdentity()) {
             delete _child_transform; // delete NULL; is safe
-            _child_transform = NULL;
+            _child_transform = nullptr;
         } else {
             _child_transform = new Geom::Affine(new_trans);
         }
@@ -89,7 +89,7 @@ DrawingGroup::_updateItem(Geom::IntRect const &area, UpdateContext const &ctx, u
 unsigned
 DrawingGroup::_renderItem(DrawingContext &dc, Geom::IntRect const &area, unsigned flags, DrawingItem *stop_at)
 {
-    if (stop_at == NULL) {
+    if (stop_at == nullptr) {
         // normal rendering
         for (ChildrenList::iterator i = _children.begin(); i != _children.end(); ++i) {
             i->setAntialiasing(_antialias);
@@ -131,7 +131,7 @@ DrawingGroup::_pickItem(Geom::Point const &p, double delta, unsigned flags)
             return _pick_children ? picked : this;
         }
     }
-    return NULL;
+    return nullptr;
 }
 
 bool
@@ -142,7 +142,7 @@ DrawingGroup::_canClip()
 
 bool is_drawing_group(DrawingItem *item)
 {
-    return dynamic_cast<DrawingGroup *>(item) != NULL;
+    return dynamic_cast<DrawingGroup *>(item) != nullptr;
 }
 
 } // end namespace Inkscape
diff --git a/src/display/drawing-image.cpp b/src/display/drawing-image.cpp
index 4be3099bf..2a3777e36 100644
--- a/src/display/drawing-image.cpp
+++ b/src/display/drawing-image.cpp
@@ -22,7 +22,7 @@ namespace Inkscape {
 
 DrawingImage::DrawingImage(Drawing &drawing)
     : DrawingItem(drawing)
-    , _pixbuf(NULL)
+    , _pixbuf(nullptr)
 {}
 
 DrawingImage::~DrawingImage()
@@ -184,7 +184,7 @@ distance_to_segment (Geom::Point const &p, Geom::Point const &a1, Geom::Point co
 DrawingItem *
 DrawingImage::_pickItem(Geom::Point const &p, double delta, unsigned /*sticky*/)
 {
-    if (!_pixbuf) return NULL;
+    if (!_pixbuf) return nullptr;
 
     bool outline = _drawing.outline();
 
@@ -201,7 +201,7 @@ DrawingImage::_pickItem(Geom::Point const &p, double delta, unsigned /*sticky*/)
                 }
             }
         }
-        return NULL;
+        return nullptr;
 
     } else {
         unsigned char *const pixels = _pixbuf->pixels();
@@ -213,7 +213,7 @@ DrawingImage::_pickItem(Geom::Point const &p, double delta, unsigned /*sticky*/)
         Geom::Rect r = bounds();
 
         if (!r.contains(tp))
-            return NULL;
+            return nullptr;
 
         double vw = width * _scale[Geom::X];
         double vh = height * _scale[Geom::Y];
@@ -221,7 +221,7 @@ DrawingImage::_pickItem(Geom::Point const &p, double delta, unsigned /*sticky*/)
         int iy = floor((tp[Geom::Y] - _origin[Geom::Y]) / vh * height);
 
         if ((ix < 0) || (iy < 0) || (ix >= width) || (iy >= height))
-            return NULL;
+            return nullptr;
 
         unsigned char *pix_ptr = pixels + iy * rowstride + ix * 4;
         // pick if the image is less than 99% transparent
@@ -235,7 +235,7 @@ DrawingImage::_pickItem(Geom::Point const &p, double delta, unsigned /*sticky*/)
             throw std::runtime_error("Unrecognized pixel format");
         }
         float alpha_f = (alpha / 255.0f) * _opacity;
-        return alpha_f > 0.01 ? this : NULL;
+        return alpha_f > 0.01 ? this : nullptr;
     }
 }
 
diff --git a/src/display/drawing-item.cpp b/src/display/drawing-item.cpp
index cc4673bc8..4f2f50ddd 100644
--- a/src/display/drawing-item.cpp
+++ b/src/display/drawing-item.cpp
@@ -107,19 +107,19 @@ void set_cairo_blend_operator( DrawingContext &dc, unsigned blend_mode ) {
 
 DrawingItem::DrawingItem(Drawing &drawing)
     : _drawing(drawing)
-    , _parent(NULL)
+    , _parent(nullptr)
     , _key(0)
-    , _style(NULL)
-    , _context_style(NULL)
+    , _style(nullptr)
+    , _context_style(nullptr)
     , _opacity(1.0)
-    , _transform(NULL)
-    , _clip(NULL)
-    , _mask(NULL)
-    , _fill_pattern(NULL)
-    , _stroke_pattern(NULL)
-    , _filter(NULL)
-    , _user_data(NULL)
-    , _cache(NULL)
+    , _transform(nullptr)
+    , _clip(nullptr)
+    , _mask(nullptr)
+    , _fill_pattern(nullptr)
+    , _stroke_pattern(nullptr)
+    , _filter(nullptr)
+    , _user_data(nullptr)
+    , _cache(nullptr)
     , _state(0)
     , _child_type(CHILD_ORPHAN)
     , _background_new(0)
@@ -163,19 +163,19 @@ DrawingItem::~DrawingItem()
     case CHILD_CLIP:
         // we cannot call setClip(NULL) or setMask(NULL),
         // because that would be an endless loop
-        _parent->_clip = NULL;
+        _parent->_clip = nullptr;
         break;
     case CHILD_MASK:
-        _parent->_mask = NULL;
+        _parent->_mask = nullptr;
         break;
     case CHILD_ROOT:
-        _drawing._root = NULL;
+        _drawing._root = nullptr;
         break;
     case CHILD_FILL_PATTERN:
-        _parent->_fill_pattern = NULL;
+        _parent->_fill_pattern = nullptr;
         break;
     case CHILD_STROKE_PATTERN:
-        _parent->_stroke_pattern = NULL;
+        _parent->_stroke_pattern = nullptr;
         break;
     default: ;
     }
@@ -273,7 +273,7 @@ DrawingItem::setTransform(Geom::Affine const &new_trans)
         _markForRendering();
         if (new_trans.isIdentity()) {
             delete _transform; // delete NULL; is safe
-            _transform = NULL;
+            _transform = nullptr;
         } else {
             _transform = new Geom::Affine(new_trans);
         }
@@ -351,7 +351,7 @@ DrawingItem::setCached(bool cached, bool persistent)
     } else {
         _drawing._cached_items.erase(this);
         delete _cache;
-        _cache = NULL;
+        _cache = nullptr;
     }
 }
 
@@ -381,7 +381,7 @@ DrawingItem::setStyle(SPStyle *style, SPStyle *context_style)
     } else {
         // no filter set for this group
         delete _filter;
-        _filter = NULL;
+        _filter = nullptr;
     }
 
     if (style && style->enable_background.set) {
@@ -394,9 +394,9 @@ DrawingItem::setStyle(SPStyle *style, SPStyle *context_style)
         }
     }
 
-    if (context_style != NULL) {
+    if (context_style != nullptr) {
         _context_style = context_style;
-    } else if (_parent != NULL) {
+    } else if (_parent != nullptr) {
         _context_style = _parent->_context_style;
     }
 
@@ -633,7 +633,7 @@ DrawingItem::update(Geom::IntRect const &area, UpdateContext const &ctx, unsigne
                 // The opposite transition (invisible -> visible or object
                 // entering the canvas) is handled during the render phase
                 delete _cache;
-                _cache = NULL;
+                _cache = nullptr;
             }
         }
     }
@@ -748,11 +748,11 @@ DrawingItem::render(DrawingContext &dc, Geom::IntRect const &area, unsigned flag
     bool needs_opacity = (_opacity < 0.995);
 
     // this item needs an intermediate rendering if:
-    nir |= (_clip != NULL); // 1. it has a clipping path
-    nir |= (_mask != NULL); // 2. it has a mask
-    nir |= (_filter != NULL && render_filters); // 3. it has a filter
+    nir |= (_clip != nullptr); // 1. it has a clipping path
+    nir |= (_mask != nullptr); // 2. it has a mask
+    nir |= (_filter != nullptr && render_filters); // 3. it has a filter
     nir |= needs_opacity; // 4. it is non-opaque
-    nir |= (_cache != NULL); // 5. it is cached
+    nir |= (_cache != nullptr); // 5. it is cached
     nir |= (_mix_blend_mode != SP_CSS_BLEND_NORMAL); // 6. Blend mode not normal
     nir |= (_isolation == SP_CSS_ISOLATION_ISOLATE); // 7. Explicit isolatiom
 
@@ -843,7 +843,7 @@ DrawingItem::render(DrawingContext &dc, Geom::IntRect const &area, unsigned flag
             }
         }
         if (!rendered) {
-            _filter->render(this, ict, NULL);
+            _filter->render(this, ict, nullptr);
         }
         // Note that because the object was rendered to a group,
         // the internals of the filter need to use cairo_get_group_target()
@@ -884,7 +884,7 @@ DrawingItem::_renderOutline(DrawingContext &dc, Geom::IntRect const &area, unsig
 
     // just render everything: item, clip, mask
     // First, render the object itself
-    _renderItem(dc, *carea, flags, NULL);
+    _renderItem(dc, *carea, flags, nullptr);
 
     // render clip and mask, if any
     guint32 saved_rgba = _drawing.outlinecolor; // save current outline color
@@ -957,11 +957,11 @@ DrawingItem::pick(Geom::Point const &p, double delta, unsigned flags)
     if (!(_state & STATE_BBOX) || !(_state & STATE_PICK)) {
         g_warning("Invalid state when picking: STATE_BBOX = %d, STATE_PICK = %d",
                   _state & STATE_BBOX, _state & STATE_PICK);
-        return NULL;
+        return nullptr;
     }
     // ignore invisible and insensitive items unless sticky
     if (!(flags & PICK_STICKY) && !(_visible && _sensitive))
-        return NULL;
+        return nullptr;
 
     bool outline = _drawing.outline();
 
@@ -969,18 +969,18 @@ DrawingItem::pick(Geom::Point const &p, double delta, unsigned flags)
         // pick inside clipping path; if NULL, it means the object is clipped away there
         if (_clip) {
             DrawingItem *cpick = _clip->pick(p, delta, flags | PICK_AS_CLIP);
-            if (!cpick) return NULL;
+            if (!cpick) return nullptr;
         }
         // same for mask
         if (_mask) {
             DrawingItem *mpick = _mask->pick(p, delta, flags);
-            if (!mpick) return NULL;
+            if (!mpick) return nullptr;
         }
     }
 
     Geom::OptIntRect box = (outline || (flags & PICK_AS_CLIP)) ? _bbox : _drawbox;
     if (!box) {
-        return NULL;
+        return nullptr;
     }
 
     Geom::Rect expanded = *box;
@@ -989,7 +989,7 @@ DrawingItem::pick(Geom::Point const &p, double delta, unsigned flags)
     if (expanded.contains(p)) {
         return _pickItem(p, delta, flags);
     }
-    return NULL;
+    return nullptr;
 }
 
 // For debugging
@@ -1042,7 +1042,7 @@ DrawingItem::_markForRendering()
     if (!dirty) return;
 
     // dirty the caches of all parents
-    DrawingItem *bkg_root = NULL;
+    DrawingItem *bkg_root = nullptr;
 
     for (DrawingItem *i = this; i; i = i->_parent) {
         if (i != this && i->_filter) {
diff --git a/src/display/drawing-item.h b/src/display/drawing-item.h
index 43015c263..b688b467c 100644
--- a/src/display/drawing-item.h
+++ b/src/display/drawing-item.h
@@ -112,7 +112,7 @@ public:
     bool cached() const { return _cached; }
     void setCached(bool c, bool persistent = false);
 
-    virtual void setStyle(SPStyle *style, SPStyle *context_style = NULL);
+    virtual void setStyle(SPStyle *style, SPStyle *context_style = nullptr);
     virtual void setChildrenStyle(SPStyle *context_style);
     void setOpacity(float opacity);
     void setAntialiasing(unsigned a);
@@ -133,7 +133,7 @@ public:
     void *data() const { return _user_data; }
 
     void update(Geom::IntRect const &area = Geom::IntRect::infinite(), UpdateContext const &ctx = UpdateContext(), unsigned flags = STATE_ALL, unsigned reset = 0);
-    unsigned render(DrawingContext &dc, Geom::IntRect const &area, unsigned flags = 0, DrawingItem *stop_at = NULL);
+    unsigned render(DrawingContext &dc, Geom::IntRect const &area, unsigned flags = 0, DrawingItem *stop_at = nullptr);
     void clip(DrawingContext &dc, Geom::IntRect const &area);
     DrawingItem *pick(Geom::Point const &p, double delta, unsigned flags = 0);
 
@@ -165,7 +165,7 @@ protected:
     virtual unsigned _renderItem(DrawingContext &/*dc*/, Geom::IntRect const &/*area*/, unsigned /*flags*/,
                                  DrawingItem * /*stop_at*/) { return RENDER_OK; }
     virtual void _clipItem(DrawingContext &/*dc*/, Geom::IntRect const &/*area*/) {}
-    virtual DrawingItem *_pickItem(Geom::Point const &/*p*/, double /*delta*/, unsigned /*flags*/) { return NULL; }
+    virtual DrawingItem *_pickItem(Geom::Point const &/*p*/, double /*delta*/, unsigned /*flags*/) { return nullptr; }
     virtual bool _canClip() { return false; }
 
     // member variables start here
diff --git a/src/display/drawing-pattern.cpp b/src/display/drawing-pattern.cpp
index b590a59c5..2cb86440e 100644
--- a/src/display/drawing-pattern.cpp
+++ b/src/display/drawing-pattern.cpp
@@ -18,7 +18,7 @@ namespace Inkscape {
 
 DrawingPattern::DrawingPattern(Drawing &drawing, bool debug)
     : DrawingGroup(drawing)
-    , _pattern_to_user(NULL)
+    , _pattern_to_user(nullptr)
     , _overflow_steps(1)
     , _debug(debug)
 {
@@ -41,7 +41,7 @@ DrawingPattern::setPatternToUserTransform(Geom::Affine const &new_trans) {
         _markForRendering();
         if (new_trans.isIdentity()) {
             delete _pattern_to_user; // delete NULL; is safe
-            _pattern_to_user = NULL;
+            _pattern_to_user = nullptr;
         } else {
             _pattern_to_user = new Geom::Affine(new_trans);
         }
@@ -67,11 +67,11 @@ DrawingPattern::renderPattern(float opacity) {
     bool visible = opacity >= 1e-3;
 
     if (!visible) {
-        return NULL;
+        return nullptr;
     }
 
     if (!_tile_rect || (_tile_rect->area() == 0)) {
-        return NULL;
+        return nullptr;
     }
     Geom::Rect pattern_tile = *_tile_rect;
 
diff --git a/src/display/drawing-shape.cpp b/src/display/drawing-shape.cpp
index d7329e670..63db9475d 100644
--- a/src/display/drawing-shape.cpp
+++ b/src/display/drawing-shape.cpp
@@ -33,8 +33,8 @@ namespace Inkscape {
 
 DrawingShape::DrawingShape(Drawing &drawing)
     : DrawingItem(drawing)
-    , _curve(NULL)
-    , _last_pick(NULL)
+    , _curve(nullptr)
+    , _last_pick(nullptr)
     , _repick_after(0)
 {}
 
@@ -51,7 +51,7 @@ DrawingShape::setPath(SPCurve *curve)
 
     if (_curve) {
         _curve->unref();
-        _curve = NULL;
+        _curve = nullptr;
     }
     if (curve) {
         _curve = curve;
@@ -312,15 +312,15 @@ DrawingShape::_pickItem(Geom::Point const &p, double delta, unsigned flags)
     if (_repick_after > 0) // we are a slow, huge path
         return _last_pick; // skip this pick, returning what was returned last time
 
-    if (!_curve) return NULL;
-    if (!_style) return NULL;
+    if (!_curve) return nullptr;
+    if (!_style) return nullptr;
 
     bool outline = _drawing.outline();
     bool pick_as_clip = flags & PICK_AS_CLIP;
 
     if (SP_SCALE24_TO_FLOAT(_style->opacity.value) == 0 && !outline && !pick_as_clip) 
         // fully transparent, no pick unless outline mode
-        return NULL;
+        return nullptr;
 
     GTimeVal tstart, tfinish;
     g_get_current_time (&tstart);
@@ -351,9 +351,9 @@ DrawingShape::_pickItem(Geom::Point const &p, double delta, unsigned flags)
     if (_drawing.arena()) {
         Geom::Rect viewbox = _drawing.arena()->item.canvas->getViewbox();
         viewbox.expandBy (width);
-        pathv_matrix_point_bbox_wind_distance(_curve->get_pathvector(), _ctm, p, NULL, needfill? &wind : NULL, &dist, 0.5, &viewbox);
+        pathv_matrix_point_bbox_wind_distance(_curve->get_pathvector(), _ctm, p, nullptr, needfill? &wind : nullptr, &dist, 0.5, &viewbox);
     } else {
-        pathv_matrix_point_bbox_wind_distance(_curve->get_pathvector(), _ctm, p, NULL, needfill? &wind : NULL, &dist, 0.5, NULL);
+        pathv_matrix_point_bbox_wind_distance(_curve->get_pathvector(), _ctm, p, nullptr, needfill? &wind : nullptr, &dist, 0.5, nullptr);
     }
 
     g_get_current_time (&tfinish);
@@ -397,8 +397,8 @@ DrawingShape::_pickItem(Geom::Point const &p, double delta, unsigned flags)
         }
     }
 
-    _last_pick = NULL;
-    return NULL;
+    _last_pick = nullptr;
+    return nullptr;
 }
 
 bool
diff --git a/src/display/drawing-shape.h b/src/display/drawing-shape.h
index 20da54239..8b0d1b082 100644
--- a/src/display/drawing-shape.h
+++ b/src/display/drawing-shape.h
@@ -28,7 +28,7 @@ public:
     ~DrawingShape() override;
 
     void setPath(SPCurve *curve);
-    void setStyle(SPStyle *style, SPStyle *context_style = NULL) override;
+    void setStyle(SPStyle *style, SPStyle *context_style = nullptr) override;
     void setChildrenStyle(SPStyle *context_style) override;
 
 protected:
diff --git a/src/display/drawing-surface.cpp b/src/display/drawing-surface.cpp
index 2752789e2..061641015 100644
--- a/src/display/drawing-surface.cpp
+++ b/src/display/drawing-surface.cpp
@@ -42,7 +42,7 @@ using Geom::Y;
  * will cover the area under the given rectangle.
  */
 DrawingSurface::DrawingSurface(Geom::IntRect const &area, int device_scale)
-    : _surface(NULL)
+    : _surface(nullptr)
     , _origin(area.min())
     , _scale(1, 1)
     , _pixels(area.dimensions())
@@ -60,7 +60,7 @@ DrawingSurface::DrawingSurface(Geom::IntRect const &area, int device_scale)
  * @param pixdims Pixel dimensions of the surface.
  */
 DrawingSurface::DrawingSurface(Geom::Rect const &logbox, Geom::IntPoint const &pixdims, int device_scale)
-    : _surface(NULL)
+    : _surface(nullptr)
     , _origin(logbox.min())
     , _scale(pixdims[X] / logbox.width(), pixdims[Y] / logbox.height())
     , _pixels(pixdims)
@@ -163,7 +163,7 @@ DrawingSurface::dropContents()
 {
     if (_surface) {
         cairo_surface_destroy(_surface);
-        _surface = NULL;
+        _surface = nullptr;
     }
 }
 
@@ -263,7 +263,7 @@ DrawingCache::prepare()
     // the area has changed, so the cache content needs to be copied
     Geom::IntPoint old_origin = old_area.min();
     cairo_surface_t *old_surface = _surface;
-    _surface = NULL;
+    _surface = nullptr;
     _pixels = _pending_area.dimensions();
     _origin = _pending_area.min();
 
diff --git a/src/display/drawing-text.cpp b/src/display/drawing-text.cpp
index aa2a744c8..a51e00606 100644
--- a/src/display/drawing-text.cpp
+++ b/src/display/drawing-text.cpp
@@ -28,7 +28,7 @@ namespace Inkscape {
 
 DrawingGlyphs::DrawingGlyphs(Drawing &drawing)
     : DrawingItem(drawing)
-    , _font(NULL)
+    , _font(nullptr)
     , _glyph(0)
 {}
 
@@ -36,7 +36,7 @@ DrawingGlyphs::~DrawingGlyphs()
 {
     if (_font) {
         _font->Unref();
-        _font = NULL;
+        _font = nullptr;
     }
 }
 
@@ -182,7 +182,7 @@ DrawingItem *DrawingGlyphs::_pickItem(Geom::Point const &p, double /*delta*/, un
     if (!ggroup) {
         throw InvalidItemException();
     }
-    DrawingItem *result = NULL;
+    DrawingItem *result = nullptr;
     bool invisible = (ggroup->_nrstyle.fill.type == NRStyle::PAINT_NONE) &&
         (ggroup->_nrstyle.stroke.type == NRStyle::PAINT_NONE);
 
@@ -684,7 +684,7 @@ void DrawingText::_clipItem(DrawingContext &dc, Geom::IntRect const &/*area*/)
 DrawingItem *
 DrawingText::_pickItem(Geom::Point const &p, double delta, unsigned flags)
 {
-    return DrawingGroup::_pickItem(p, delta, flags) ? this : NULL;
+    return DrawingGroup::_pickItem(p, delta, flags) ? this : nullptr;
 }
 
 bool
diff --git a/src/display/drawing-text.h b/src/display/drawing-text.h
index 376182d4e..fdfab122f 100644
--- a/src/display/drawing-text.h
+++ b/src/display/drawing-text.h
@@ -28,7 +28,7 @@ public:
     ~DrawingGlyphs() override;
 
     void setGlyph(font_instance *font, int glyph, Geom::Affine const &trans);
-    void setStyle(SPStyle *style, SPStyle *context_style = NULL) override; // Not to be used
+    void setStyle(SPStyle *style, SPStyle *context_style = nullptr) override; // Not to be used
 
 protected:
     unsigned _updateItem(Geom::IntRect const &area, UpdateContext const &ctx,
@@ -57,7 +57,7 @@ public:
     void clear();
     bool addComponent(font_instance *font, int glyph, Geom::Affine const &trans, 
         float width, float ascent, float descent, float phase_length);
-    void setStyle(SPStyle *style, SPStyle *context_style = NULL) override;
+    void setStyle(SPStyle *style, SPStyle *context_style = nullptr) override;
     void setChildrenStyle(SPStyle *context_style) override;
 
 protected:
diff --git a/src/display/drawing.cpp b/src/display/drawing.cpp
index 71fb94be0..18c2d98e8 100644
--- a/src/display/drawing.cpp
+++ b/src/display/drawing.cpp
@@ -31,7 +31,7 @@ static const gdouble grayscale_value_matrix[20] = {
 };
 
 Drawing::Drawing(SPCanvasArena *arena)
-    : _root(NULL)
+    : _root(nullptr)
     , outlinecolor(0x000000ff)
     , delta(0)
     , _exact(false)
@@ -198,7 +198,7 @@ Drawing::pick(Geom::Point const &p, double delta, unsigned flags)
     if (_root) {
         return _root->pick(p, delta, flags);
     }
-    return NULL;
+    return nullptr;
 }
 
 void
diff --git a/src/display/drawing.h b/src/display/drawing.h
index e472c8f5b..1348f02af 100644
--- a/src/display/drawing.h
+++ b/src/display/drawing.h
@@ -40,7 +40,7 @@ public:
         guint32 images;
     };
 
-    Drawing(SPCanvasArena *arena = NULL);
+    Drawing(SPCanvasArena *arena = nullptr);
     ~Drawing();
 
     DrawingItem *root() { return _root; }
diff --git a/src/display/gnome-canvas-acetate.cpp b/src/display/gnome-canvas-acetate.cpp
index 297d69068..50d26a068 100644
--- a/src/display/gnome-canvas-acetate.cpp
+++ b/src/display/gnome-canvas-acetate.cpp
@@ -41,7 +41,7 @@ static void sp_canvas_acetate_init (SPCanvasAcetate */*acetate*/)
 
 static void sp_canvas_acetate_destroy(SPCanvasItem *object)
 {
-	g_return_if_fail (object != NULL);
+	g_return_if_fail (object != nullptr);
 	g_return_if_fail (GNOME_IS_CANVAS_ACETATE (object));
 
 	if (SP_CANVAS_ITEM_CLASS(sp_canvas_acetate_parent_class)->destroy)
diff --git a/src/display/guideline.cpp b/src/display/guideline.cpp
index cde10f6c2..8091f8369 100644
--- a/src/display/guideline.cpp
+++ b/src/display/guideline.cpp
@@ -53,13 +53,13 @@ static void sp_guideline_init(SPGuideLine *gl)
     gl->point_on_line = Geom::Point(0,0);
     gl->sensitive = 0;
 
-    gl->origin = NULL;
-    gl->label = NULL;
+    gl->origin = nullptr;
+    gl->label = nullptr;
 }
 
 static void sp_guideline_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_GUIDELINE (object));
 
     SPGuideLine *gl = SP_GUIDELINE(object);
@@ -200,7 +200,7 @@ static double sp_guideline_point(SPCanvasItem *item, Geom::Point p, SPCanvasItem
 
 SPCanvasItem *sp_guideline_new(SPCanvasGroup *parent, char* label, Geom::Point point_on_line, Geom::Point normal)
 {
-    SPCanvasItem *item = sp_canvas_item_new(parent, SP_TYPE_GUIDELINE, NULL);
+    SPCanvasItem *item = sp_canvas_item_new(parent, SP_TYPE_GUIDELINE, nullptr);
     SPGuideLine *gl = SP_GUIDELINE(item);
 
     normal.normalize();
diff --git a/src/display/nr-filter-colormatrix.cpp b/src/display/nr-filter-colormatrix.cpp
index 77873d523..5f477ae9b 100644
--- a/src/display/nr-filter-colormatrix.cpp
+++ b/src/display/nr-filter-colormatrix.cpp
@@ -151,7 +151,7 @@ struct ColorMatrixLuminanceToAlpha {
 void FilterColorMatrix::render_cairo(FilterSlot &slot)
 {
     cairo_surface_t *input = slot.getcairo(_input);
-    cairo_surface_t *out = NULL;
+    cairo_surface_t *out = nullptr;
 
     // We may need to transform input surface to correct color interpolation space. The input surface
     // might be used as input to another primitive but it is likely that all the primitives in a given
diff --git a/src/display/nr-filter-gaussian.cpp b/src/display/nr-filter-gaussian.cpp
index 2227edfef..5cc8f74fd 100644
--- a/src/display/nr-filter-gaussian.cpp
+++ b/src/display/nr-filter-gaussian.cpp
@@ -637,7 +637,7 @@ void FilterGaussian::render_cairo(FilterSlot &slot)
         }
     }
 
-    cairo_surface_t *downsampled = NULL;
+    cairo_surface_t *downsampled = nullptr;
     if (resampling) {
         // Divide by device scale as w_downsampled is in pixels while
         // cairo_surface_create_similar() uses device units.
diff --git a/src/display/nr-filter-image.cpp b/src/display/nr-filter-image.cpp
index 551a86cbf..b8b45b40b 100644
--- a/src/display/nr-filter-image.cpp
+++ b/src/display/nr-filter-image.cpp
@@ -27,10 +27,10 @@ namespace Inkscape {
 namespace Filters {
 
 FilterImage::FilterImage()
-    : SVGElem(0)
-    , document(0)
-    , feImageHref(0)
-    , image(0)
+    : SVGElem(nullptr)
+    , document(nullptr)
+    , feImageHref(nullptr)
+    , image(nullptr)
     , broken_ref(false)
 { }
 
@@ -309,10 +309,10 @@ double FilterImage::complexity(Geom::Affine const &)
 void FilterImage::set_href(const gchar *href){
 
     if (feImageHref) g_free (feImageHref);
-    feImageHref = (href) ? g_strdup (href) : NULL;
+    feImageHref = (href) ? g_strdup (href) : nullptr;
 
     delete image;
-    image = NULL;
+    image = nullptr;
     broken_ref = false;
 }
 
diff --git a/src/display/nr-filter-merge.cpp b/src/display/nr-filter-merge.cpp
index fc2ce408f..316df84f0 100644
--- a/src/display/nr-filter-merge.cpp
+++ b/src/display/nr-filter-merge.cpp
@@ -43,7 +43,7 @@ void FilterMerge::render_cairo(FilterSlot &slot)
 
     // output is RGBA if at least one input is RGBA
     bool rgba32 = false;
-    cairo_surface_t *out = NULL;
+    cairo_surface_t *out = nullptr;
     for (std::vector<int>::iterator i = _input_image.begin(); i != _input_image.end(); ++i) {
         cairo_surface_t *in = slot.getcairo(*i);
         if (cairo_surface_get_content(in) == CAIRO_CONTENT_COLOR_ALPHA) {
diff --git a/src/display/nr-filter-primitive.cpp b/src/display/nr-filter-primitive.cpp
index ec392ea06..c6be75e16 100644
--- a/src/display/nr-filter-primitive.cpp
+++ b/src/display/nr-filter-primitive.cpp
@@ -46,7 +46,7 @@ FilterPrimitive::FilterPrimitive()
     _subregion_width.unset(SVGLength::PERCENT, 1, 0);
     _subregion_height.unset(SVGLength::PERCENT, 1, 0);
 
-    _style = NULL;
+    _style = nullptr;
 }
 
 FilterPrimitive::~FilterPrimitive()
diff --git a/src/display/nr-filter-slot.cpp b/src/display/nr-filter-slot.cpp
index 9d76462c0..1358530b8 100644
--- a/src/display/nr-filter-slot.cpp
+++ b/src/display/nr-filter-slot.cpp
@@ -29,7 +29,7 @@ FilterSlot::FilterSlot(DrawingItem *item, DrawingContext *bgdc,
         DrawingContext &graphic, FilterUnits const &u)
     : _item(item)
     , _source_graphic(graphic.rawTarget())
-    , _background_ct(bgdc ? bgdc->raw() : NULL)
+    , _background_ct(bgdc ? bgdc->raw() : nullptr)
     , _source_graphic_area(graphic.targetLogicalBounds().roundOutwards()) // fixme
     , _background_area(bgdc ? bgdc->targetLogicalBounds().roundOutwards() : Geom::IntRect()) // fixme
     , _units(u)
@@ -223,7 +223,7 @@ void FilterSlot::_set_internal(int slot_nr, cairo_surface_t *surface)
 
 void FilterSlot::set(int slot_nr, cairo_surface_t *surface)
 {
-    g_return_if_fail(surface != NULL);
+    g_return_if_fail(surface != nullptr);
 
     if (slot_nr == NR_FILTER_SLOT_NOT_SET)
         slot_nr = NR_FILTER_UNNAMED_SLOT;
diff --git a/src/display/nr-filter.cpp b/src/display/nr-filter.cpp
index 4782f3f54..6f8798a2a 100644
--- a/src/display/nr-filter.cpp
+++ b/src/display/nr-filter.cpp
@@ -367,7 +367,7 @@ int Filter::replace_primitive(int target, FilterPrimitiveType type)
 }
 
 FilterPrimitive *Filter::get_primitive(int handle) {
-    if (handle < 0 || handle >= static_cast<int>(_primitive.size())) return NULL;
+    if (handle < 0 || handle >= static_cast<int>(_primitive.size())) return nullptr;
     return _primitive[handle];
 }
 
diff --git a/src/display/nr-style.cpp b/src/display/nr-style.cpp
index 31bb27755..cec6de4d3 100644
--- a/src/display/nr-style.cpp
+++ b/src/display/nr-style.cpp
@@ -19,8 +19,8 @@
 void NRStyle::Paint::clear()
 {
     if (server) {
-        sp_object_unref(server, NULL);
-        server = NULL;
+        sp_object_unref(server, nullptr);
+        server = nullptr;
     }
     type = PAINT_NONE;
 }
@@ -38,7 +38,7 @@ void NRStyle::Paint::set(SPPaintServer *ps)
     if (ps) {
         type = PAINT_SERVER;
         server = ps;
-        sp_object_ref(server, NULL);
+        sp_object_ref(server, nullptr);
     }
 }
 
@@ -48,15 +48,15 @@ NRStyle::NRStyle()
     , stroke_width(0.0)
     , miter_limit(0.0)
     , n_dash(0)
-    , dash(NULL)
+    , dash(nullptr)
     , dash_offset(0.0)
     , fill_rule(CAIRO_FILL_RULE_EVEN_ODD)
     , line_cap(CAIRO_LINE_CAP_BUTT)
     , line_join(CAIRO_LINE_JOIN_MITER)
-    , fill_pattern(NULL)
-    , stroke_pattern(NULL)
-    , text_decoration_fill_pattern(NULL)
-    , text_decoration_stroke_pattern(NULL)
+    , fill_pattern(nullptr)
+    , stroke_pattern(nullptr)
+    , text_decoration_fill_pattern(nullptr)
+    , text_decoration_stroke_pattern(nullptr)
     , text_decoration_line(TEXT_DECORATION_LINE_CLEAR)
     , text_decoration_style(TEXT_DECORATION_STYLE_CLEAR)
     , text_decoration_fill()
@@ -97,14 +97,14 @@ void NRStyle::set(SPStyle *style, SPStyle *context_style)
     // Handle 'context-fill' and 'context-stroke': Work in progress
     const SPIPaint *style_fill = &(style->fill);
     if( style_fill->paintOrigin == SP_CSS_PAINT_ORIGIN_CONTEXT_FILL ) {
-        if( context_style != NULL ) {
+        if( context_style != nullptr ) {
             style_fill = &(context_style->fill);
         } else {
             // A marker in the defs section will result in ending up here.
             //std::cerr << "NRStyle::set: 'context-fill': 'context_style' is NULL" << std::endl;
         }
     } else if ( style_fill->paintOrigin == SP_CSS_PAINT_ORIGIN_CONTEXT_STROKE ) {
-        if( context_style != NULL ) {
+        if( context_style != nullptr ) {
             style_fill = &(context_style->stroke);
         } else {
             //std::cerr << "NRStyle::set: 'context-stroke': 'context_style' is NULL" << std::endl;
@@ -148,13 +148,13 @@ void NRStyle::set(SPStyle *style, SPStyle *context_style)
 
     const SPIPaint *style_stroke = &(style->stroke);
     if( style_stroke->paintOrigin == SP_CSS_PAINT_ORIGIN_CONTEXT_FILL ) {
-        if( context_style != NULL ) {
+        if( context_style != nullptr ) {
             style_stroke = &(context_style->fill);
         } else {
             //std::cerr << "NRStyle::set: 'context-fill': 'context_style' is NULL" << std::endl;
         }
     } else if ( style_stroke->paintOrigin == SP_CSS_PAINT_ORIGIN_CONTEXT_STROKE ) {
-        if( context_style != NULL ) {
+        if( context_style != nullptr ) {
             style_stroke = &(context_style->stroke);
         } else {
             //std::cerr << "NRStyle::set: 'context-stroke': 'context_style' is NULL" << std::endl;
@@ -225,7 +225,7 @@ void NRStyle::set(SPStyle *style, SPStyle *context_style)
         }
     } else {
         dash_offset = 0.0;
-        dash = NULL;
+        dash = nullptr;
     }
 
 
@@ -472,7 +472,7 @@ void NRStyle::applyTextDecorationStroke(Inkscape::DrawingContext &dc)
     dc.setLineCap(CAIRO_LINE_CAP_BUTT);
     dc.setLineJoin(CAIRO_LINE_JOIN_MITER);
     dc.setMiterLimit(miter_limit);
-    cairo_set_dash(dc.raw(), 0, 0, 0.0); // fixme (no dash)
+    cairo_set_dash(dc.raw(), nullptr, 0, 0.0); // fixme (no dash)
 }
 
 void NRStyle::update()
@@ -482,10 +482,10 @@ void NRStyle::update()
     if (stroke_pattern) cairo_pattern_destroy(stroke_pattern);
     if (text_decoration_fill_pattern) cairo_pattern_destroy(text_decoration_fill_pattern);
     if (text_decoration_stroke_pattern) cairo_pattern_destroy(text_decoration_stroke_pattern);
-    fill_pattern = NULL;
-    stroke_pattern = NULL;
-    text_decoration_fill_pattern = NULL;
-    text_decoration_stroke_pattern = NULL;
+    fill_pattern = nullptr;
+    stroke_pattern = nullptr;
+    text_decoration_fill_pattern = nullptr;
+    text_decoration_stroke_pattern = nullptr;
 }
 
 /*
diff --git a/src/display/nr-style.h b/src/display/nr-style.h
index 6c652311a..354b9dd8b 100644
--- a/src/display/nr-style.h
+++ b/src/display/nr-style.h
@@ -29,7 +29,7 @@ struct NRStyle {
     NRStyle();
     ~NRStyle();
 
-    void set(SPStyle *style, SPStyle *context_style = NULL);
+    void set(SPStyle *style, SPStyle *context_style = nullptr);
     bool prepareFill(Inkscape::DrawingContext &dc, Geom::OptRect const &paintbox, Inkscape::DrawingPattern *pattern);
     bool prepareStroke(Inkscape::DrawingContext &dc, Geom::OptRect const &paintbox, Inkscape::DrawingPattern *pattern);
     bool prepareTextDecorationFill(Inkscape::DrawingContext &dc, Geom::OptRect const &paintbox, Inkscape::DrawingPattern *pattern);
@@ -47,7 +47,7 @@ struct NRStyle {
     };
 
     struct Paint {
-        Paint() : type(PAINT_NONE), color(0), server(NULL), opacity(1.0) {}
+        Paint() : type(PAINT_NONE), color(0), server(nullptr), opacity(1.0) {}
         ~Paint() { clear(); }
 
         PaintType type;
diff --git a/src/display/nr-svgfonts.cpp b/src/display/nr-svgfonts.cpp
index c3354bc0b..e2b112c1b 100644
--- a/src/display/nr-svgfonts.cpp
+++ b/src/display/nr-svgfonts.cpp
@@ -79,7 +79,7 @@ UserFont::UserFont(SvgFont* instance){
     cairo_user_font_face_set_render_glyph_func  (this->face, font_render_glyph_cb);
     cairo_user_font_face_set_text_to_glyphs_func(this->face, font_text_to_glyphs_cb);
 
-    cairo_font_face_set_user_data (this->face, &key, (void*)instance, (cairo_destroy_func_t) NULL);
+    cairo_font_face_set_user_data (this->face, &key, (void*)instance, (cairo_destroy_func_t) nullptr);
 }
 
 //******************************//
@@ -87,8 +87,8 @@ UserFont::UserFont(SvgFont* instance){
 //******************************//
 SvgFont::SvgFont(SPFont* spfont){
     this->font = spfont;
-    this->missingglyph = NULL;
-    this->userfont = NULL;
+    this->missingglyph = nullptr;
+    this->userfont = nullptr;
 }
 
 cairo_status_t
@@ -191,8 +191,8 @@ SvgFont::scaled_font_text_to_glyphs (cairo_scaled_font_t  */*scaled_font*/,
     //We use that info to allocate memory for the glyphs
     *glyphs = (cairo_glyph_t*) malloc(count*sizeof(cairo_glyph_t));
 
-    char* previous_unicode = NULL; //This is used for kerning
-    gchar* previous_glyph_name = NULL; //This is used for kerning
+    char* previous_unicode = nullptr; //This is used for kerning
+    gchar* previous_glyph_name = nullptr; //This is used for kerning
 
     count=0;
     double x=0, y=0;//These vars store the position of the glyph within the rendered string
@@ -312,7 +312,7 @@ SvgFont::scaled_font_render_glyph (cairo_scaled_font_t  */*scaled_font*/,
 
     if (glyph > this->glyphs.size())     return CAIRO_STATUS_SUCCESS;//TODO: this is an error!
 
-    SPObject *node = NULL;
+    SPObject *node = nullptr;
     if (glyph == glyphs.size()){
         if (!missingglyph) {
             return CAIRO_STATUS_SUCCESS;
@@ -370,7 +370,7 @@ SvgFont::scaled_font_render_glyph (cairo_scaled_font_t  */*scaled_font*/,
                 SPPath *path = dynamic_cast<SPPath *>(item);
                 if (path) {
                     SPShape *shape = dynamic_cast<SPShape *>(item);
-                    g_assert(shape != NULL);
+                    g_assert(shape != nullptr);
                     pathv = shape->_curve->get_pathvector();
                     pathv = flip_coordinate_system(spfont, pathv);
                     this->render_glyph_path(cr, &pathv);
@@ -405,7 +405,7 @@ SvgFont::get_font_face(){
 void SvgFont::refresh(){
     this->glyphs.clear();
     delete this->userfont;
-    this->userfont = NULL;
+    this->userfont = nullptr;
 }
 
 double SvgFont::units_per_em() {
diff --git a/src/display/snap-indicator.cpp b/src/display/snap-indicator.cpp
index f2271e0c6..2e329c4aa 100644
--- a/src/display/snap-indicator.cpp
+++ b/src/display/snap-indicator.cpp
@@ -29,10 +29,10 @@ namespace Inkscape {
 namespace Display {
 
 SnapIndicator::SnapIndicator(SPDesktop * desktop)
-    :   _snaptarget(NULL),
-        _snaptarget_tooltip(NULL),
-        _snaptarget_bbox(NULL),
-        _snapsource(NULL),
+    :   _snaptarget(nullptr),
+        _snaptarget_tooltip(nullptr),
+        _snaptarget_bbox(nullptr),
+        _snapsource(nullptr),
         _snaptarget_is_presnap(false),
         _desktop(desktop)
 {
@@ -50,7 +50,7 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
 {
     remove_snaptarget(); //only display one snaptarget at a time
 
-    g_assert(_desktop != NULL);
+    g_assert(_desktop != nullptr);
 
     if (!p.getSnapped()) {
         return; // If we haven't snapped, then it is of no use to draw a snapindicator
@@ -245,7 +245,7 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
         remove_snapsource(); // Don't set both the source and target indicators, as these will overlap
 
         // Display the snap indicator (i.e. the cross)
-        SPCanvasItem * canvasitem = NULL;
+        SPCanvasItem * canvasitem = nullptr;
         canvasitem = sp_canvas_item_new(_desktop->getTempGroup(),
                                         SP_TYPE_CTRL,
                                         "anchor", SP_ANCHOR_CENTER,
@@ -281,7 +281,7 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
         _snaptarget_is_presnap = pre_snap;
 
         // Display the tooltip, which reveals the type of snap source and the type of snap target
-        gchar *tooltip_str = NULL;
+        gchar *tooltip_str = nullptr;
         if ( (p.getSource() != SNAPSOURCE_GRID_PITCH) && (p.getTarget() != SNAPTARGET_UNDEFINED) ) {
             tooltip_str = g_strconcat(source_name, _(" to "), target_name, NULL);
         } else if (p.getSource() != SNAPSOURCE_UNDEFINED) {
@@ -320,7 +320,7 @@ SnapIndicator::set_new_snaptarget(Inkscape::SnappedPoint const &p, bool pre_snap
         if (bbox) {
             SPCanvasItem* box = sp_canvas_item_new(_desktop->getTempGroup(),
                                                      SP_TYPE_CTRLRECT,
-                                                     NULL);
+                                                     nullptr);
 
             SP_CTRLRECT(box)->setRectangle(*bbox);
             SP_CTRLRECT(box)->setColor(pre_snap ? 0x7f7f7fff : 0xff0000ff, 0, 0);
@@ -341,18 +341,18 @@ SnapIndicator::remove_snaptarget(bool only_if_presnap)
 
     if (_snaptarget) {
         _desktop->remove_temporary_canvasitem(_snaptarget);
-        _snaptarget = NULL;
+        _snaptarget = nullptr;
         _snaptarget_is_presnap = false;
     }
 
     if (_snaptarget_tooltip) {
         _desktop->remove_temporary_canvasitem(_snaptarget_tooltip);
-        _snaptarget_tooltip = NULL;
+        _snaptarget_tooltip = nullptr;
     }
 
     if (_snaptarget_bbox) {
         _desktop->remove_temporary_canvasitem(_snaptarget_bbox);
-        _snaptarget_bbox = NULL;
+        _snaptarget_bbox = nullptr;
     }
 
 }
@@ -362,7 +362,7 @@ SnapIndicator::set_new_snapsource(Inkscape::SnapCandidatePoint const &p)
 {
     remove_snapsource();
 
-    g_assert(_desktop != NULL); // If this fails, then likely setup() has not been called on the snap manager (see snap.cpp -> setup())
+    g_assert(_desktop != nullptr); // If this fails, then likely setup() has not been called on the snap manager (see snap.cpp -> setup())
 
     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
     bool value = prefs->getBool("/options/snapindicator/value", true);
@@ -386,7 +386,7 @@ SnapIndicator::set_new_snapsource(Inkscape::SnapCandidatePoint const &p)
 void
 SnapIndicator::set_new_debugging_point(Geom::Point const &p)
 {
-    g_assert(_desktop != NULL);
+    g_assert(_desktop != nullptr);
     SPCanvasItem * canvasitem = sp_canvas_item_new( _desktop->getTempGroup(),
                                                     SP_TYPE_CTRL,
                                                     "anchor", SP_ANCHOR_CENTER,
@@ -407,7 +407,7 @@ SnapIndicator::remove_snapsource()
 {
     if (_snapsource) {
         _desktop->remove_temporary_canvasitem(_snapsource);
-        _snapsource = NULL;
+        _snapsource = nullptr;
     }
 }
 
diff --git a/src/display/sodipodi-ctrl.cpp b/src/display/sodipodi-ctrl.cpp
index 04ec947f6..45db82a93 100644
--- a/src/display/sodipodi-ctrl.cpp
+++ b/src/display/sodipodi-ctrl.cpp
@@ -79,7 +79,7 @@ sp_ctrl_set_property(GObject *object, guint prop_id, const GValue *value, GParam
 
     SPCanvasItem *item;
     SPCtrl *ctrl;
-    GdkPixbuf * pixbuf = NULL;
+    GdkPixbuf * pixbuf = nullptr;
 
     item = SP_CANVAS_ITEM (object);
     ctrl = SP_CTRL (object);
@@ -206,22 +206,22 @@ sp_ctrl_init (SPCtrl *ctrl)
     ctrl->angle = 0.0;
 
     new (&ctrl->box) Geom::IntRect(0,0,0,0);
-    ctrl->cache = NULL;
-    ctrl->pixbuf = NULL;
+    ctrl->cache = nullptr;
+    ctrl->pixbuf = nullptr;
 
     ctrl->_point = Geom::Point(0,0);
 }
 
 static void sp_ctrl_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_CTRL (object));
 
     SPCtrl *ctrl = SP_CTRL (object);
 
     if (ctrl->cache) {
         delete[] ctrl->cache;
-        ctrl->cache = NULL;
+        ctrl->cache = nullptr;
     }
 
     if (SP_CANVAS_ITEM_CLASS(sp_ctrl_parent_class)->destroy)
diff --git a/src/display/sp-canvas-util.cpp b/src/display/sp-canvas-util.cpp
index 25b70824b..e6c6ea839 100644
--- a/src/display/sp-canvas-util.cpp
+++ b/src/display/sp-canvas-util.cpp
@@ -42,7 +42,7 @@ void sp_canvas_prepare_buffer(SPCanvasBuf *)
 
 Geom::Affine sp_canvas_item_i2p_affine (SPCanvasItem * item)
 {
-    g_assert (item != NULL); /* this may be overly zealous - it is
+    g_assert (item != nullptr); /* this may be overly zealous - it is
                               * plausible that this gets called
                               * with item == 0. */
 
@@ -51,22 +51,22 @@ Geom::Affine sp_canvas_item_i2p_affine (SPCanvasItem * item)
 
 Geom::Affine  sp_canvas_item_i2i_affine (SPCanvasItem * from, SPCanvasItem * to)
 {
-    g_assert (from != NULL);
-    g_assert (to != NULL);
+    g_assert (from != nullptr);
+    g_assert (to != nullptr);
 
     return sp_canvas_item_i2w_affine(from) * sp_canvas_item_i2w_affine(to).inverse();
 }
 
 void sp_canvas_item_set_i2w_affine (SPCanvasItem * item,  Geom::Affine const &i2w)
 {
-    g_assert (item != NULL);
+    g_assert (item != nullptr);
 
     sp_canvas_item_affine_absolute(item, i2w * sp_canvas_item_i2w_affine(item->parent).inverse());
 }
 
 void sp_canvas_item_move_to_z (SPCanvasItem * item, gint z)
 {
-    g_assert (item != NULL);
+    g_assert (item != nullptr);
     
     if (z == 0)
         return sp_canvas_item_lower_to_bottom(item);
diff --git a/src/display/sp-canvas.cpp b/src/display/sp-canvas.cpp
index c717bc7ae..6a38ae3e7 100644
--- a/src/display/sp-canvas.cpp
+++ b/src/display/sp-canvas.cpp
@@ -49,7 +49,7 @@ using Inkscape::Debug::GdkEventLatencyTracker;
 
 // gtk_check_version returns non-NULL on failure
 static bool const HAS_BROKEN_MOTION_HINTS =
-  true || gtk_check_version(2, 12, 0) != NULL;
+  true || gtk_check_version(2, 12, 0) != nullptr;
 
 // Define this to visualize the regions to be redrawn
 //#define DEBUG_REDRAW 1;
@@ -209,7 +209,7 @@ sp_canvas_item_class_init(SPCanvasItemClass *klass)
                                              G_TYPE_FROM_CLASS (klass),
                                              G_SIGNAL_RUN_LAST,
                                              ((glong)((guint8*)&(klass->event) - (guint8*)klass)),
-                                             NULL, NULL,
+                                             nullptr, nullptr,
                                              sp_marshal_BOOLEAN__POINTER,
                                              G_TYPE_BOOLEAN, 1,
                                              GDK_TYPE_EVENT);
@@ -223,7 +223,7 @@ sp_canvas_item_class_init(SPCanvasItemClass *klass)
                     G_TYPE_FROM_CLASS (gobject_class),
                     (GSignalFlags)(G_SIGNAL_RUN_CLEANUP | G_SIGNAL_NO_RECURSE | G_SIGNAL_NO_HOOKS),
 		    G_STRUCT_OFFSET (SPCanvasItemClass, destroy),
-		    NULL, NULL,
+		    nullptr, nullptr,
 		    g_cclosure_marshal_VOID__VOID,
 		    G_TYPE_NONE, 0);
 }
@@ -248,11 +248,11 @@ SPCanvasItem *sp_canvas_item_new(SPCanvasGroup *parent, GType type, gchar const
 {
     va_list args;
 
-    g_return_val_if_fail(parent != NULL, NULL);
+    g_return_val_if_fail(parent != nullptr, NULL);
     g_return_val_if_fail(SP_IS_CANVAS_GROUP(parent), NULL);
     g_return_val_if_fail(g_type_is_a(type, SP_TYPE_CANVAS_ITEM), NULL);
 
-    SPCanvasItem *item = SP_CANVAS_ITEM(g_object_new(type, NULL));
+    SPCanvasItem *item = SP_CANVAS_ITEM(g_object_new(type, nullptr));
 
     va_start(args, first_arg_name);
     sp_canvas_item_construct(item, parent, first_arg_name, args);
@@ -329,22 +329,22 @@ void sp_canvas_item_dispose(GObject *object)
       item->visible = FALSE;
 
       if (item == item->canvas->_current_item) {
-          item->canvas->_current_item = NULL;
+          item->canvas->_current_item = nullptr;
           item->canvas->_need_repick = TRUE;
       }
 
       if (item == item->canvas->_new_current_item) {
-          item->canvas->_new_current_item = NULL;
+          item->canvas->_new_current_item = nullptr;
           item->canvas->_need_repick = TRUE;
       }
 
       if (item == item->canvas->_grabbed_item) {
-          item->canvas->_grabbed_item = NULL;
+          item->canvas->_grabbed_item = nullptr;
           ungrab_default_client_pointer();
       }
 
       if (item == item->canvas->_focused_item) {
-          item->canvas->_focused_item = NULL;
+          item->canvas->_focused_item = nullptr;
       }
 
       if (item->parent) {
@@ -439,7 +439,7 @@ void sp_canvas_item_affine_absolute(SPCanvasItem *item, Geom::Affine const &affi
 
     if (!item->need_affine) {
         item->need_affine = TRUE;
-        if (item->parent != NULL) {
+        if (item->parent != nullptr) {
             sp_canvas_item_request_update (item->parent);
         } else {
             item->canvas->requestUpdate();
@@ -460,7 +460,7 @@ void sp_canvas_item_affine_absolute(SPCanvasItem *item, Geom::Affine const &affi
  */
 void sp_canvas_item_raise(SPCanvasItem *item, int positions)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
     g_return_if_fail (positions >= 0);
 
@@ -484,7 +484,7 @@ void sp_canvas_item_raise(SPCanvasItem *item, int positions)
 
 void sp_canvas_item_raise_to_top(SPCanvasItem *item)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
     if (!item->parent)
         return;
@@ -508,7 +508,7 @@ void sp_canvas_item_raise_to_top(SPCanvasItem *item)
  */
 void sp_canvas_item_lower(SPCanvasItem *item, int positions)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
     g_return_if_fail (positions >= 1);
 
@@ -533,7 +533,7 @@ void sp_canvas_item_lower(SPCanvasItem *item, int positions)
 
 void sp_canvas_item_lower_to_bottom(SPCanvasItem *item)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
     if (!item->parent)
         return;
@@ -554,7 +554,7 @@ bool sp_canvas_item_is_visible(SPCanvasItem *item)
  */
 void sp_canvas_item_show(SPCanvasItem *item)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
 
     if (item->visible) {
@@ -579,7 +579,7 @@ void sp_canvas_item_show(SPCanvasItem *item)
  */
 void sp_canvas_item_hide(SPCanvasItem *item)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
 
     if (!item->visible) {
@@ -606,7 +606,7 @@ void sp_canvas_item_hide(SPCanvasItem *item)
  */
 int sp_canvas_item_grab(SPCanvasItem *item, guint event_mask, GdkCursor *cursor, guint32 etime)
 {
-    g_return_val_if_fail (item != NULL, -1);
+    g_return_val_if_fail (item != nullptr, -1);
     g_return_val_if_fail (SP_IS_CANVAS_ITEM (item), -1);
     g_return_val_if_fail (gtk_widget_get_mapped (GTK_WIDGET (item->canvas)), -1);
 
@@ -637,9 +637,9 @@ int sp_canvas_item_grab(SPCanvasItem *item, guint event_mask, GdkCursor *cursor,
                   GDK_SEAT_CAPABILITY_ALL_POINTING,
                   FALSE,
                   cursor,
-                  NULL,
-                  NULL,
-                  NULL);
+                  nullptr,
+                  nullptr,
+                  nullptr);
 #else
     auto dm = gdk_display_get_device_manager(display);
     auto device = gdk_device_manager_get_client_pointer(dm);
@@ -669,14 +669,14 @@ int sp_canvas_item_grab(SPCanvasItem *item, guint event_mask, GdkCursor *cursor,
  */
 void sp_canvas_item_ungrab(SPCanvasItem *item, guint32 etime)
 {
-    g_return_if_fail (item != NULL);
+    g_return_if_fail (item != nullptr);
     g_return_if_fail (SP_IS_CANVAS_ITEM (item));
 
     if (item->canvas->_grabbed_item != item) {
         return;
     }
 
-    item->canvas->_grabbed_item = NULL;
+    item->canvas->_grabbed_item = nullptr;
     ungrab_default_client_pointer(etime);
 }
 
@@ -726,7 +726,7 @@ void sp_canvas_item_request_update(SPCanvasItem *item)
 
     item->need_update = TRUE;
 
-    if (item->parent != NULL) {
+    if (item->parent != nullptr) {
         // Recurse up the tree
         sp_canvas_item_request_update (item->parent);
     } else {
@@ -772,7 +772,7 @@ static void sp_canvas_group_init(SPCanvasGroup * group)
 
 void SPCanvasGroup::destroy(SPCanvasItem *object)
 {
-    g_return_if_fail(object != NULL);
+    g_return_if_fail(object != nullptr);
     g_return_if_fail(SP_IS_CANVAS_GROUP(object));
 
     SPCanvasGroup *group = SP_CANVAS_GROUP(object);
@@ -827,14 +827,14 @@ double SPCanvasGroup::point(SPCanvasItem *item, Geom::Point p, SPCanvasItem **ac
     int y2 = (int)(y + item->canvas->_close_enough);
 
     double best = 0.0;
-    *actual_item = NULL;
+    *actual_item = nullptr;
 
     double dist = 0.0;
     for (std::list<SPCanvasItem *>::const_iterator it = group->items.begin(); it != group->items.end(); ++it) {
         SPCanvasItem *child = *it;
 
         if ((child->x1 <= x2) && (child->y1 <= y2) && (child->x2 >= x1) && (child->y2 >= y1)) {
-            SPCanvasItem *point_item = NULL; // cater for incomplete item implementations
+            SPCanvasItem *point_item = nullptr; // cater for incomplete item implementations
 
             int pickable;
             if (child->visible && child->pickable && SP_CANVAS_ITEM_GET_CLASS(child)->point) {
@@ -905,7 +905,7 @@ void SPCanvasGroup::add(SPCanvasItem *item)
 
 void SPCanvasGroup::remove(SPCanvasItem *item)
 {
-    g_return_if_fail(item != NULL);
+    g_return_if_fail(item != nullptr);
 
     auto position = std::find(items.begin(), items.end(), item);
     if (position != items.end()) {
@@ -913,7 +913,7 @@ void SPCanvasGroup::remove(SPCanvasItem *item)
     }
 
     // Unparent the child
-    item->parent = NULL;
+    item->parent = nullptr;
     g_object_unref(item);
 
 }
@@ -955,7 +955,7 @@ static void sp_canvas_init(SPCanvas *canvas)
     canvas->_pick_event.crossing.y = 0;
 
     // Create the root item as a special case
-    canvas->_root = SP_CANVAS_ITEM(g_object_new(SP_TYPE_CANVAS_GROUP, NULL));
+    canvas->_root = SP_CANVAS_ITEM(g_object_new(SP_TYPE_CANVAS_GROUP, nullptr));
     canvas->_root->canvas = canvas;
 
     g_object_ref (canvas->_root);
@@ -968,9 +968,9 @@ static void sp_canvas_init(SPCanvas *canvas)
 
     canvas->_drawing_disabled = false;
 
-    canvas->_backing_store = NULL;
+    canvas->_backing_store = nullptr;
 #if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 12, 0)
-    canvas->_surface_for_similar = NULL;
+    canvas->_surface_for_similar = nullptr;
 #endif
     canvas->_clean_region = cairo_region_create();
     canvas->_background = cairo_pattern_create_rgb(1, 1, 1);
@@ -991,7 +991,7 @@ void SPCanvas::shutdownTransients()
     dirtyAll();
 
     if (_grabbed_item) {
-        _grabbed_item = NULL;
+        _grabbed_item = nullptr;
         ungrab_default_client_pointer();
     }
     removeIdle();
@@ -1003,25 +1003,25 @@ void SPCanvas::dispose(GObject *object)
 
     if (canvas->_root) {
         g_object_unref (canvas->_root);
-        canvas->_root = NULL;
+        canvas->_root = nullptr;
     }
     if (canvas->_backing_store) {
         cairo_surface_destroy(canvas->_backing_store);
-        canvas->_backing_store = NULL;
+        canvas->_backing_store = nullptr;
     }
 #if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 12, 0)
     if (canvas->_surface_for_similar) {
         cairo_surface_destroy(canvas->_surface_for_similar);
-        canvas->_surface_for_similar = NULL;
+        canvas->_surface_for_similar = nullptr;
     }
 #endif
     if (canvas->_clean_region) {
         cairo_region_destroy(canvas->_clean_region);
-        canvas->_clean_region = NULL;
+        canvas->_clean_region = nullptr;
     }
     if (canvas->_background) {
         cairo_pattern_destroy(canvas->_background);
-        canvas->_background = NULL;
+        canvas->_background = nullptr;
     }
 
     canvas->shutdownTransients();
@@ -1048,7 +1048,7 @@ void trackLatency(GdkEvent const *event)
 
 GtkWidget *SPCanvas::createAA()
 {
-    SPCanvas *canvas = SP_CANVAS(g_object_new(SP_TYPE_CANVAS, NULL));
+    SPCanvas *canvas = SP_CANVAS(g_object_new(SP_TYPE_CANVAS, nullptr));
     return GTK_WIDGET(canvas);
 }
 
@@ -1099,9 +1099,9 @@ void SPCanvas::handle_unrealize(GtkWidget *widget)
 {
     SPCanvas *canvas = SP_CANVAS (widget);
 
-    canvas->_current_item = NULL;
-    canvas->_grabbed_item = NULL;
-    canvas->_focused_item = NULL;
+    canvas->_current_item = nullptr;
+    canvas->_grabbed_item = nullptr;
+    canvas->_focused_item = nullptr;
 
     canvas->shutdownTransients();
 
@@ -1138,9 +1138,9 @@ void SPCanvas::handle_size_allocate(GtkWidget *widget, GtkAllocation *allocation
         allocation->width, allocation->height);
 
     // Resize backing store.
-    cairo_surface_t *new_backing_store = NULL;
+    cairo_surface_t *new_backing_store = nullptr;
 #if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 12, 0)
-    if (canvas->_surface_for_similar != NULL) {
+    if (canvas->_surface_for_similar != nullptr) {
 
         // Size in device pixels. Does not set device scale.
         new_backing_store =
@@ -1150,7 +1150,7 @@ void SPCanvas::handle_size_allocate(GtkWidget *widget, GtkAllocation *allocation
                                                allocation->height * canvas->_device_scale);
     }
 #endif
-    if (new_backing_store == NULL) {
+    if (new_backing_store == nullptr) {
 
         // Size in device pixels. Does not set device scale.
         new_backing_store =
@@ -1268,7 +1268,7 @@ int SPCanvas::emitEvent(GdkEvent *event)
     // (e.g. if the pointer leaves the window).  So this is a hack that
     // Lauris applied to SP to get around the problem.
     //
-    SPCanvasItem* item = NULL;
+    SPCanvasItem* item = nullptr;
     if (_grabbed_item && !is_descendant(_current_item, _grabbed_item)) {
         item = _grabbed_item;
     } else {
@@ -1333,7 +1333,7 @@ int SPCanvas::pickCurrentItem(GdkEvent *event)
             _pick_event.crossing.type       = GDK_ENTER_NOTIFY;
             _pick_event.crossing.window     = event->motion.window;
             _pick_event.crossing.send_event = event->motion.send_event;
-            _pick_event.crossing.subwindow  = NULL;
+            _pick_event.crossing.subwindow  = nullptr;
             _pick_event.crossing.x          = event->motion.x;
             _pick_event.crossing.y          = event->motion.y;
             _pick_event.crossing.mode       = GDK_CROSSING_NORMAL;
@@ -1381,10 +1381,10 @@ int SPCanvas::pickCurrentItem(GdkEvent *event)
         if (_root->visible) {
             sp_canvas_item_invoke_point (_root, Geom::Point(x, y), &_new_current_item);
         } else {
-            _new_current_item = NULL;
+            _new_current_item = nullptr;
         }
     } else {
-        _new_current_item = NULL;
+        _new_current_item = nullptr;
     }
 
     if ((_new_current_item == _current_item) && !_left_grabbed_item) {
@@ -1394,7 +1394,7 @@ int SPCanvas::pickCurrentItem(GdkEvent *event)
     // Synthesize events for old and new current items
 
     if ((_new_current_item != _current_item) &&
-        _current_item != NULL && !_left_grabbed_item)
+        _current_item != nullptr && !_left_grabbed_item)
     {
         GdkEvent new_event;
 
@@ -1402,7 +1402,7 @@ int SPCanvas::pickCurrentItem(GdkEvent *event)
         new_event.type = GDK_LEAVE_NOTIFY;
 
         new_event.crossing.detail = GDK_NOTIFY_ANCESTOR;
-        new_event.crossing.subwindow = NULL;
+        new_event.crossing.subwindow = nullptr;
         _in_repick = TRUE;
         retval = emitEvent(&new_event);
         _in_repick = FALSE;
@@ -1421,13 +1421,13 @@ int SPCanvas::pickCurrentItem(GdkEvent *event)
     _left_grabbed_item = FALSE;
     _current_item = _new_current_item;
 
-    if (_current_item != NULL) {
+    if (_current_item != nullptr) {
         GdkEvent new_event;
 
         new_event = _pick_event;
         new_event.type = GDK_ENTER_NOTIFY;
         new_event.crossing.detail = GDK_NOTIFY_ANCESTOR;
-        new_event.crossing.subwindow = NULL;
+        new_event.crossing.subwindow = nullptr;
         retval = emitEvent(&new_event);
     }
 
@@ -1508,7 +1508,7 @@ gint SPCanvas::handle_scroll(GtkWidget *widget, GdkEventScroll *event)
 static inline void request_motions(GdkWindow *w, GdkEventMotion *event) {
     gdk_window_get_device_position(w,
                                    gdk_event_get_device((GdkEvent *)(event)),
-                                   NULL, NULL, NULL);
+                                   nullptr, nullptr, nullptr);
     gdk_event_request_motions(event);
 }
 
@@ -1523,7 +1523,7 @@ int SPCanvas::handle_motion(GtkWidget *widget, GdkEventMotion *event)
         return FALSE;
     }
 
-    if (canvas->_root == NULL) // canvas being deleted
+    if (canvas->_root == nullptr) // canvas being deleted
         return FALSE;
 
     canvas->_state = event->state;
@@ -1541,11 +1541,11 @@ void SPCanvas::paintSingleBuffer(Geom::IntRect const &paint_rect, Geom::IntRect
 
     // Prevent crash if paintSingleBuffer is called before _backing_store is
     // initialized.
-    if (_backing_store == NULL)
+    if (_backing_store == nullptr)
         return;
 
     SPCanvasBuf buf;
-    buf.buf = NULL;
+    buf.buf = nullptr;
     buf.buf_rowstride = 0;
     buf.rect = paint_rect;
     buf.canvas_rect = canvas_rect;
@@ -1604,7 +1604,7 @@ void SPCanvas::paintSingleBuffer(Geom::IntRect const &paint_rect, Geom::IntRect
 
 #if defined(HAVE_LIBLCMS1) || defined(HAVE_LIBLCMS2)
     if (_enable_cms_display_adj) {
-        cmsHTRANSFORM transf = 0;
+        cmsHTRANSFORM transf = nullptr;
         Inkscape::Preferences *prefs = Inkscape::Preferences::get();
         bool fromDisplay = prefs->getBool( "/options/displayprofile/from_display");
         if ( fromDisplay ) {
@@ -1788,7 +1788,7 @@ bool SPCanvas::paintRect(int xx0, int yy0, int xx1, int yy1)
 
     gdk_window_get_device_position(gtk_widget_get_window(GTK_WIDGET(this)),
                                    device->gobj(),
-                                   &x, &y, NULL);
+                                   &x, &y, nullptr);
 
     setup.mouse_loc = sp_canvas_window_to_world(this, Geom::Point(x,y));
 
@@ -1828,7 +1828,7 @@ gboolean SPCanvas::handle_draw(GtkWidget *widget, cairo_t *cr) {
     SPCanvas *canvas = SP_CANVAS(widget);
 
 #if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 12, 0)
-    if (canvas->_surface_for_similar == NULL && canvas->_backing_store != NULL) {
+    if (canvas->_surface_for_similar == nullptr && canvas->_backing_store != nullptr) {
 
         // Device scale is copied but since this is only created one time, we'll
         // need to check/set device scale anytime it is used in case window moved
@@ -2011,7 +2011,7 @@ gint SPCanvas::idle_handler(gpointer data)
 void SPCanvas::addIdle()
 {
     if (_idle_id == 0) {
-        _idle_id = gdk_threads_add_idle_full(UPDATE_PRIORITY, idle_handler, this, NULL);
+        _idle_id = gdk_threads_add_idle_full(UPDATE_PRIORITY, idle_handler, this, nullptr);
     }
 }
 void SPCanvas::removeIdle()
@@ -2055,9 +2055,9 @@ void SPCanvas::scrollTo( Geom::Point const &c, unsigned int clear, bool is_scrol
     // Adjust backing store contents
     assert(_backing_store);
 
-    cairo_surface_t *new_backing_store = NULL;
+    cairo_surface_t *new_backing_store = nullptr;
 #if CAIRO_VERSION >= CAIRO_VERSION_ENCODE(1, 12, 0)
-    if (_surface_for_similar != NULL)
+    if (_surface_for_similar != nullptr)
 
         // Size in device pixels. Does not set device scale.
         new_backing_store =
@@ -2066,7 +2066,7 @@ void SPCanvas::scrollTo( Geom::Point const &c, unsigned int clear, bool is_scrol
                                                allocation.width  * _device_scale,
                                                allocation.height * _device_scale);
 #endif
-    if (new_backing_store == NULL)
+    if (new_backing_store == nullptr)
 
         // Size in device pixels. Does not set device scale.
         new_backing_store =
@@ -2158,7 +2158,7 @@ void SPCanvas::setBackgroundColor(guint32 rgba) {
     double new_b = SP_RGBA32_B_F(rgba);
     if (!_background_is_checkerboard) {
         double old_r, old_g, old_b;
-        cairo_pattern_get_rgba(_background, &old_r, &old_g, &old_b, NULL);
+        cairo_pattern_get_rgba(_background, &old_r, &old_g, &old_b, nullptr);
         if (new_r == old_r && new_g == old_g && new_b == old_b) return;
     }
     if (_background) {
@@ -2186,7 +2186,7 @@ void SPCanvas::setBackgroundCheckerboard() {
  */
 void sp_canvas_window_to_world(SPCanvas const *canvas, double winx, double winy, double *worldx, double *worldy)
 {
-    g_return_if_fail (canvas != NULL);
+    g_return_if_fail (canvas != nullptr);
     g_return_if_fail (SP_IS_CANVAS (canvas));
 
     if (worldx) *worldx = canvas->_x0 + winx;
@@ -2198,7 +2198,7 @@ void sp_canvas_window_to_world(SPCanvas const *canvas, double winx, double winy,
  */
 void sp_canvas_world_to_window(SPCanvas const *canvas, double worldx, double worldy, double *winx, double *winy)
 {
-    g_return_if_fail (canvas != NULL);
+    g_return_if_fail (canvas != nullptr);
     g_return_if_fail (SP_IS_CANVAS (canvas));
 
     if (winx) *winx = worldx - canvas->_x0;
@@ -2210,7 +2210,7 @@ void sp_canvas_world_to_window(SPCanvas const *canvas, double worldx, double wor
  */
 Geom::Point sp_canvas_window_to_world(SPCanvas const *canvas, Geom::Point const win)
 {
-    g_assert (canvas != NULL);
+    g_assert (canvas != nullptr);
     g_assert (SP_IS_CANVAS (canvas));
 
     return Geom::Point(canvas->_x0 + win[0], canvas->_y0 + win[1]);
@@ -2221,7 +2221,7 @@ Geom::Point sp_canvas_window_to_world(SPCanvas const *canvas, Geom::Point const
  */
 Geom::Point sp_canvas_world_to_window(SPCanvas const *canvas, Geom::Point const world)
 {
-    g_assert (canvas != NULL);
+    g_assert (canvas != nullptr);
     g_assert (SP_IS_CANVAS (canvas));
 
     return Geom::Point(world[0] - canvas->_x0, world[1] - canvas->_y0);
@@ -2234,7 +2234,7 @@ bool sp_canvas_world_pt_inside_window(SPCanvas const *canvas, Geom::Point const
 {
     GtkAllocation allocation;
 
-    g_assert( canvas != NULL );
+    g_assert( canvas != nullptr );
     g_assert(SP_IS_CANVAS(canvas));
 
     GtkWidget *w = GTK_WIDGET(canvas);
diff --git a/src/display/sp-ctrlcurve.cpp b/src/display/sp-ctrlcurve.cpp
index 79ef20d6c..26a3c2055 100644
--- a/src/display/sp-ctrlcurve.cpp
+++ b/src/display/sp-ctrlcurve.cpp
@@ -46,7 +46,7 @@ sp_ctrlcurve_init(SPCtrlCurve *ctrlcurve)
 {
     // Points are initialized to 0,0
     ctrlcurve->rgba = 0x0000ff7f;
-    ctrlcurve->item=NULL;
+    ctrlcurve->item=nullptr;
     ctrlcurve->corner0 = -1;
     ctrlcurve->corner1 = -1;
 }
@@ -55,12 +55,12 @@ namespace {
 static void
 sp_ctrlcurve_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_CTRLCURVE (object));
 
     SPCtrlCurve *ctrlcurve = SP_CTRLCURVE (object);
 
-    ctrlcurve->item=NULL;
+    ctrlcurve->item=nullptr;
 
     if (SP_CANVAS_ITEM_CLASS(sp_ctrlcurve_parent_class)->destroy)
         SP_CANVAS_ITEM_CLASS(sp_ctrlcurve_parent_class)->destroy(object);
diff --git a/src/display/sp-ctrlline.cpp b/src/display/sp-ctrlline.cpp
index c4ced2a33..709f85e54 100644
--- a/src/display/sp-ctrlline.cpp
+++ b/src/display/sp-ctrlline.cpp
@@ -51,19 +51,19 @@ static void sp_ctrlline_init(SPCtrlLine *ctrlline)
 {
     ctrlline->rgba = 0x0000ff7f;
     ctrlline->s[Geom::X] = ctrlline->s[Geom::Y] = ctrlline->e[Geom::X] = ctrlline->e[Geom::Y] = 0.0;
-    ctrlline->item=NULL;
+    ctrlline->item=nullptr;
     ctrlline->is_fill = true;
 }
 
 namespace {
 void sp_ctrlline_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail(object != NULL);
+    g_return_if_fail(object != nullptr);
     g_return_if_fail(SP_IS_CTRLLINE(object));
 
     SPCtrlLine *ctrlline = SP_CTRLLINE(object);
 
-    ctrlline->item = NULL;
+    ctrlline->item = nullptr;
 
     if(SP_CANVAS_ITEM_CLASS (sp_ctrlline_parent_class)->destroy) {
        SP_CANVAS_ITEM_CLASS (sp_ctrlline_parent_class)->destroy(object);
diff --git a/src/display/sp-ctrlquadr.cpp b/src/display/sp-ctrlquadr.cpp
index 760e93a6d..40c011e26 100644
--- a/src/display/sp-ctrlquadr.cpp
+++ b/src/display/sp-ctrlquadr.cpp
@@ -58,7 +58,7 @@ sp_ctrlquadr_init (SPCtrlQuadr *ctrlquadr)
 
 static void sp_ctrlquadr_destroy(SPCanvasItem *object)
 {
-    g_return_if_fail (object != NULL);
+    g_return_if_fail (object != nullptr);
     g_return_if_fail (SP_IS_CTRLQUADR (object));
 
     if (SP_CANVAS_ITEM_CLASS(sp_ctrlquadr_parent_class)->destroy)
@@ -139,7 +139,7 @@ static void sp_ctrlquadr_update(SPCanvasItem *item, Geom::Affine const &affine,
 void
 sp_ctrlquadr_set_rgba32 (SPCtrlQuadr *cl, guint32 rgba)
 {
-    g_return_if_fail (cl != NULL);
+    g_return_if_fail (cl != nullptr);
     g_return_if_fail (SP_IS_CTRLQUADR (cl));
 
     if (rgba != cl->rgba) {
@@ -153,7 +153,7 @@ sp_ctrlquadr_set_rgba32 (SPCtrlQuadr *cl, guint32 rgba)
 void
 sp_ctrlquadr_set_coords (SPCtrlQuadr *cl, Geom::Point p1, Geom::Point p2, Geom::Point p3, Geom::Point p4)
 {
-    g_return_if_fail (cl != NULL);
+    g_return_if_fail (cl != nullptr);
     g_return_if_fail (SP_IS_CTRLQUADR (cl));
 
     if (p1 != cl->p1 || p2 != cl->p2 || p3 != cl->p3 || p4 != cl->p4) {