Adding upstream version 1.2.2.upstream/1.2.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 739 insertions, 0 deletions

diff --git a/src/live_effects/lpe-knot.cpp b/src/live_effects/lpe-knot.cpp
new file mode 100644
index 0000000..602b857
--- /dev/null
+++ b/src/live_effects/lpe-knot.cpp
@@ -0,0 +1,739 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * LPE knot effect implementation.
+ */
+/* Authors:
+ *   Jean-Francois Barraud <jf.barraud@gmail.com>
+ *   Abhishek Sharma
+ *   Johan Engelen
+ *
+ * Copyright (C) 2007-2012 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <gdk/gdk.h>
+#include <optional>
+
+#include <2geom/sbasis-to-bezier.h>
+#include <2geom/bezier-to-sbasis.h>
+#include <2geom/basic-intersection.h>
+
+#include "lpe-knot.h"
+
+// for change crossing undo
+#include "document.h"
+#include "document-undo.h"
+
+#include "style.h"
+
+#include "display/curve.h"
+
+#include "helper/geom.h"
+
+#include "object/sp-path.h"
+#include "object/sp-shape.h"
+
+#include "ui/icon-names.h"
+#include "ui/knot/knot-holder.h"
+#include "ui/knot/knot-holder-entity.h"
+
+
+// TODO due to internal breakage in glibmm headers, this must be last:
+#include <glibmm/i18n.h>
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+class KnotHolderEntityCrossingSwitcher : public LPEKnotHolderEntity {
+public:
+    KnotHolderEntityCrossingSwitcher(LPEKnot *effect) : LPEKnotHolderEntity(effect) {};
+    void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
+    Geom::Point knot_get() const override;
+    void knot_click(guint state) override;
+};
+
+
+static Geom::Path::size_type size_nondegenerate(Geom::Path const &path) {
+    Geom::Path::size_type retval = path.size_default();
+    const Geom::Curve &closingline = path.back_closed();
+    // the closing line segment is always of type
+    // Geom::LineSegment.
+    if (are_near(closingline.initialPoint(), closingline.finalPoint())) {
+        // closingline.isDegenerate() did not work, because it only checks for
+        // *exact* zero length, which goes wrong for relative coordinates and
+        // rounding errors...
+        // the closing line segment has zero-length. So stop before that one!
+        retval = path.size_open();
+    }
+    return retval;
+}
+
+//---------------------------------------------------------------------------
+//LPEKnot specific Interval manipulation.
+//---------------------------------------------------------------------------
+
+//remove an interval from an union of intervals.
+//TODO: is it worth moving it to 2Geom?
+static
+std::vector<Geom::Interval> complementOf(Geom::Interval I, std::vector<Geom::Interval> domain){
+    std::vector<Geom::Interval> ret;
+    if (!domain.empty()) {
+        double min = domain.front().min();
+        double max = domain.back().max();
+        Geom::Interval I1 = Geom::Interval(min,I.min());
+        Geom::Interval I2 = Geom::Interval(I.max(),max);
+
+        for (auto i : domain){
+            std::optional<Geom::Interval> I1i = intersect(i,I1);
+            if (I1i && !I1i->isSingular()) ret.push_back(*I1i);
+            std::optional<Geom::Interval> I2i = intersect(i,I2);
+            if (I2i && !I2i->isSingular()) ret.push_back(*I2i);
+        }
+    }
+    return ret;
+}
+
+//find the time interval during which patha is hidden by pathb near a given crossing.
+// Warning: not accurate!
+static
+Geom::Interval
+findShadowedTime(Geom::Path const &patha, std::vector<Geom::Point> const &pt_and_dir,
+                 double const ta, double const width){
+    using namespace Geom;
+    Point T = unit_vector(pt_and_dir[1]);
+    Point N = T.cw();
+    //Point A = pt_and_dir[0] - 3 * width * T;
+    //Point B = A+6*width*T;
+
+    Affine mat = from_basis( T, N, pt_and_dir[0] );
+    mat = mat.inverse();
+    Geom::Path p = patha * mat;
+    
+    std::vector<double> times;
+    
+    //TODO: explore the path fwd/backward from ta (worth?)
+    for (unsigned i = 0; i < size_nondegenerate(patha); i++){
+        D2<SBasis> f = p[i].toSBasis();
+        std::vector<double> times_i, temptimes;
+        temptimes = roots(f[Y]-width);
+        times_i.insert(times_i.end(), temptimes.begin(), temptimes.end() ); 
+        temptimes = roots(f[Y]+width);
+        times_i.insert(times_i.end(), temptimes.begin(), temptimes.end() ); 
+        temptimes = roots(f[X]-3*width);
+        times_i.insert(times_i.end(), temptimes.begin(), temptimes.end() ); 
+        temptimes = roots(f[X]+3*width);
+        times_i.insert(times_i.end(), temptimes.begin(), temptimes.end() );
+        for (double & k : times_i){
+            k+=i;
+        }
+        times.insert(times.end(), times_i.begin(), times_i.end() );
+    }
+    std::sort( times.begin(),  times.end() );
+    std::vector<double>::iterator new_end = std::unique( times.begin(),  times.end() );
+    times.resize( new_end - times.begin() );
+
+    double tmin = 0, tmax = size_nondegenerate(patha);
+    double period = size_nondegenerate(patha);
+    if (!times.empty()){
+        unsigned rk = upper_bound( times.begin(),  times.end(), ta ) - times.begin();
+        if ( rk < times.size() ) 
+            tmax = times[rk];
+        else if ( patha.closed() ) 
+            tmax = times[0]+period;
+
+        if ( rk > 0 ) 
+            tmin = times[rk-1];
+        else if ( patha.closed() ) 
+            tmin = times.back()-period;
+    }
+    return Interval(tmin,tmax);
+}
+
+//---------------------------------------------------------------------------
+//LPEKnot specific Crossing Data manipulation.
+//---------------------------------------------------------------------------
+
+//Yet another crossing data representation.
+// an CrossingPoint stores
+//    -an intersection point
+//    -the involved path components
+//    -for each component, the time at which this crossing occurs + the order of this crossing along the component (when starting from 0).
+
+namespace LPEKnotNS {//just in case...
+CrossingPoints::CrossingPoints(Geom::PathVector const &paths) : std::vector<CrossingPoint>(){
+//    std::cout<<"\nCrossingPoints creation from path vector\n";
+    for( unsigned i=0; i<paths.size(); i++){
+        for( unsigned ii=0; ii < size_nondegenerate(paths[i]); ii++){
+            for( unsigned j=i; j<paths.size(); j++){
+                for( unsigned jj=(i==j?ii:0); jj < size_nondegenerate(paths[j]); jj++){
+                    std::vector<std::pair<double,double> > times;
+                    if ( (i==j) && (ii==jj) ) {
+
+//                         std::cout<<"--(self int)\n";
+//                         std::cout << paths[i][ii].toSBasis()[Geom::X] <<"\n";
+//                         std::cout << paths[i][ii].toSBasis()[Geom::Y] <<"\n";
+
+                        find_self_intersections( times, paths[i][ii].toSBasis() );
+                    } else {
+//                         std::cout<<"--(pair int)\n";
+//                         std::cout << paths[i][ii].toSBasis()[Geom::X] <<"\n";
+//                         std::cout << paths[i][ii].toSBasis()[Geom::Y] <<"\n";
+//                         std::cout<<"with\n";
+//                         std::cout << paths[j][jj].toSBasis()[Geom::X] <<"\n";
+//                         std::cout << paths[j][jj].toSBasis()[Geom::Y] <<"\n";
+
+                        find_intersections( times, paths[i][ii].toSBasis(), paths[j][jj].toSBasis() );
+                    }
+                    for (auto & time : times){
+                        //std::cout<<"intersection "<<i<<"["<<ii<<"]("<<times[k].first<<")= "<<j<<"["<<jj<<"]("<<times[k].second<<")\n";
+                        if ( !std::isnan(time.first) && !std::isnan(time.second) ){
+                            double zero = 1e-4;
+                            if ( (i==j) && (fabs(time.first+ii - time.second-jj) <= zero) )
+                            { //this is just end=start of successive curves in a path.
+                                continue;
+                            }
+                            if ( (i==j) && (ii == 0) && (jj == size_nondegenerate(paths[i])-1)
+                                 && paths[i].closed()
+                                 && (fabs(time.first) <= zero)
+                                 && (fabs(time.second - 1) <= zero) )
+                            {//this is just end=start of a closed path.
+                                continue;
+                            }
+                            CrossingPoint cp;
+                            cp.pt = paths[i][ii].pointAt(time.first);
+                            cp.sign = 1;
+                            cp.i = i;
+                            cp.j = j;
+                            cp.ni = 0; cp.nj=0;//not set yet
+                            cp.ti = time.first + ii;
+                            cp.tj = time.second + jj;
+                            push_back(cp);
+                        }else{
+                            std::cout<<"ooops: find_(self)_intersections returned NaN:" << std::endl;
+                            //std::cout<<"intersection "<<i<<"["<<ii<<"](NaN)= "<<j<<"["<<jj<<"](NaN)\n";
+                        }
+                    }
+                }
+            }
+        }
+    }
+    for( unsigned i=0; i<paths.size(); i++){
+        std::map < double, unsigned > cuts;
+        for( unsigned k=0; k<size(); k++){
+            CrossingPoint cp = (*this)[k];
+            if (cp.i == i) cuts[cp.ti] = k;
+            if (cp.j == i) cuts[cp.tj] = k;
+        }
+        unsigned count = 0;
+        for (auto & cut : cuts){
+            if ( ((*this)[cut.second].i == i) && ((*this)[cut.second].ti == cut.first) ){
+                (*this)[cut.second].ni = count;
+            }else{
+                (*this)[cut.second].nj = count;
+            }
+            count++;
+        }
+    }
+}
+
+CrossingPoints::CrossingPoints(std::vector<double> const &input) : std::vector<CrossingPoint>()
+{
+    if ( (input.size() > 0) && (input.size()%9 == 0) ){
+        using namespace Geom;
+        for( unsigned n=0; n<input.size();  ){
+            CrossingPoint cp;
+            cp.pt[X] = input[n++];
+            cp.pt[Y] = input[n++];
+            cp.i = input[n++];
+            cp.j = input[n++];
+            cp.ni = input[n++];
+            cp.nj = input[n++];
+            cp.ti = input[n++];
+            cp.tj = input[n++];
+            cp.sign = input[n++];
+            push_back(cp);
+        }
+    }
+}
+
+std::vector<double>
+CrossingPoints::to_vector()
+{
+    using namespace Geom;
+    std::vector<double> result;
+    for( unsigned n=0; n<size(); n++){
+        CrossingPoint cp = (*this)[n];
+        result.push_back(cp.pt[X]);
+        result.push_back(cp.pt[Y]);
+        result.push_back(double(cp.i));
+        result.push_back(double(cp.j));
+        result.push_back(double(cp.ni));
+        result.push_back(double(cp.nj));
+        result.push_back(double(cp.ti));
+        result.push_back(double(cp.tj));
+        result.push_back(double(cp.sign));
+    }
+    return result;
+}
+
+//FIXME: rewrite to check success: return bool, put result in arg.
+CrossingPoint
+CrossingPoints::get(unsigned const i, unsigned const ni)
+{
+    for (unsigned k=0; k<size(); k++){
+        if (    ( ((*this)[k].i==i) && ((*this)[k].ni==ni) )
+             || ( ((*this)[k].j==i) && ((*this)[k].nj==ni) )  )
+        {
+            return (*this)[k];
+        }
+    }
+    g_warning("LPEKnotNS::CrossingPoints::get error. %uth crossing along string %u not found.",ni,i);
+    assert(false);//debug purpose...
+    return CrossingPoint();
+}
+
+static unsigned
+idx_of_nearest(CrossingPoints const &cpts, Geom::Point const &p)
+{
+    double dist=-1;
+    unsigned result = cpts.size();
+    for (unsigned k=0; k<cpts.size(); k++){
+        double dist_k = Geom::L2(p-cpts[k].pt);
+        if ( (dist < 0) || (dist > dist_k) ) {
+            result = k;
+            dist = dist_k;
+        }
+    }
+    return result;
+}
+
+//TODO: Find a way to warn the user when the topology changes.
+//TODO: be smarter at guessing the signs when the topology changed?
+void
+CrossingPoints::inherit_signs(CrossingPoints const &other, int default_value)
+{
+    bool topo_changed = false;
+    for (unsigned n=0; n < size(); n++){
+        if ( (n < other.size())
+             && (other[n].i  == (*this)[n].i)
+             && (other[n].j  == (*this)[n].j)
+             && (other[n].ni == (*this)[n].ni)
+             && (other[n].nj == (*this)[n].nj) )
+        {
+            (*this)[n].sign = other[n].sign;
+        } else {
+            topo_changed = true;
+            break;
+        }
+    }
+    if (topo_changed) {
+        //TODO: Find a way to warn the user!!
+//        std::cout<<"knot topolgy changed!\n";
+        for (unsigned n=0; n < size(); n++){
+            Geom::Point p = (*this)[n].pt;
+            unsigned idx = idx_of_nearest(other,p);
+            if (idx < other.size()) {
+                (*this)[n].sign = other[idx].sign;
+            } else {
+                (*this)[n].sign = default_value;
+            }
+        }
+    }
+}
+
+}
+
+//---------------------------------------------------------------------------
+//---------------------------------------------------------------------------
+//LPEKnot effect.
+//---------------------------------------------------------------------------
+//---------------------------------------------------------------------------
+
+
+LPEKnot::LPEKnot(LivePathEffectObject *lpeobject)
+    : Effect(lpeobject)
+    ,
+    // initialise your parameters here:
+    interruption_width(_("_Gap length:"), _("Size of hidden region of lower string"), "interruption_width", &wr, this,
+                       3)
+    , prop_to_stroke_width(
+          _("_In units of stroke width"),
+          _("Gap width is given in multiples of stroke width. When unchecked, document units are used."),
+          "prop_to_stroke_width", &wr, this, true)
+    , both(_("_Gaps in both"), _("At path intersections, both parts will have a gap"), "both", &wr, this, false)
+    , inverse_width(_("_Groups: Inverse"), _("Use other stroke width, useful in groups with different stroke widths"),
+                    "inverse_width", &wr, this, false)
+    , add_stroke_width("St_roke width", "Add the stroke width to the gap size", "add_stroke_width", &wr, this,
+                       "inkscape_1.0_and_up", true)
+    , add_other_stroke_width("_Crossing path stroke width", "Add crossed stroke width to the gap size",
+                             "add_other_stroke_width", &wr, this, "inkscape_1.0_and_up", true)
+    , switcher_size(_("S_witcher size:"), _("Orientation indicator/switcher size"), "switcher_size", &wr, this, 15)
+    , crossing_points_vector(_("Crossing Signs"), _("Crossing signs"), "crossing_points_vector", &wr, this)
+    , crossing_points()
+    , gpaths()
+    , gstroke_widths()
+    , selectedCrossing(0)
+    , switcher(0., 0.)
+{
+    // register all your parameters here, so Inkscape knows which parameters this effect has:
+    registerParameter(&switcher_size);
+    registerParameter(&interruption_width);
+    registerParameter(&prop_to_stroke_width);
+    registerParameter(&add_stroke_width);
+    registerParameter(&both);
+    registerParameter(&inverse_width);
+    registerParameter(&add_other_stroke_width);
+    registerParameter(&crossing_points_vector);
+
+    _provides_knotholder_entities = true;
+}
+
+LPEKnot::~LPEKnot()
+= default;
+
+void
+LPEKnot::updateSwitcher(){
+    if (selectedCrossing < crossing_points.size()){
+        switcher = crossing_points[selectedCrossing].pt;
+        //std::cout<<"placing switcher at "<<switcher<<" \n";
+    }else if (crossing_points.size()>0){
+        selectedCrossing = 0;
+        switcher = crossing_points[selectedCrossing].pt;
+        //std::cout<<"placing switcher at "<<switcher<<" \n";
+    }else{
+        //std::cout<<"hiding switcher!\n";
+        switcher = Geom::Point(Geom::infinity(),Geom::infinity());
+    }
+}
+
+Geom::PathVector
+LPEKnot::doEffect_path (Geom::PathVector const &path_in)
+{
+    using namespace Geom;
+    Geom::PathVector path_out;
+
+    if (gpaths.size()==0){
+        return path_in;
+    }
+    Geom::PathVector const original_pathv = pathv_to_linear_and_cubic_beziers(path_in);
+    for (const auto & comp : original_pathv){
+
+        //find the relevant path component in gpaths (required to allow groups!)
+        //Q: do we always receive the group members in the same order? can we rest on that?
+        unsigned i0 = 0;
+        Inkscape::Preferences *prefs = Inkscape::Preferences::get();
+        gint precision = prefs->getInt("/options/svgoutput/numericprecision");
+        prefs->setInt("/options/svgoutput/numericprecision", 4); // I think this is enough for minor differences
+        for (i0=0; i0<gpaths.size(); i0++){
+            if (sp_svg_write_path(comp) == sp_svg_write_path(gpaths[i0]))
+                break;
+        }
+        prefs->setInt("/options/svgoutput/numericprecision", precision);
+        if (i0 == gpaths.size() ) {THROW_EXCEPTION("lpe-knot error: group member not recognized");}// this should not happen...
+
+        std::vector<Interval> dom;
+        dom.emplace_back(0., size_nondegenerate(gpaths[i0]));
+        for (unsigned p = 0; p < crossing_points.size(); p++){
+            if ( (crossing_points[p].i == i0) || (crossing_points[p].j == i0) ) {
+                unsigned i = crossing_points[p].i;
+                unsigned j = crossing_points[p].j;
+                double ti = crossing_points[p].ti;
+                double tj = crossing_points[p].tj;
+                
+                double curveidx, t;
+                
+                t = modf(ti, &curveidx);
+                if(curveidx == size_nondegenerate(gpaths[i]) ) { curveidx--; t = 1.;}
+                assert(curveidx >= 0 && curveidx < size_nondegenerate(gpaths[i]));
+                std::vector<Point> flag_i = gpaths[i][curveidx].pointAndDerivatives(t,1);
+
+                t = modf(tj, &curveidx);
+                if(curveidx == size_nondegenerate(gpaths[j]) ) { curveidx--; t = 1.;}
+                assert(curveidx >= 0 && curveidx < size_nondegenerate(gpaths[j]));
+                std::vector<Point> flag_j = gpaths[j][curveidx].pointAndDerivatives(t,1);
+
+
+                int geom_sign = ( cross(flag_i[1], flag_j[1]) < 0 ? 1 : -1);
+                bool i0_is_under = false;
+                double width = interruption_width;
+                if ( crossing_points[p].sign * geom_sign > 0 ){
+                    i0_is_under = ( i == i0 );
+                }
+                else if (crossing_points[p].sign * geom_sign < 0) {
+                    if (j == i0){
+                        i0_is_under = true;
+                    }
+                }
+                i0_is_under = crossing_points[p].sign != 0 && both ? true : i0_is_under;
+                if (i0_is_under && j == i0) {
+                    // last check of sign makes sure we get different outputs when
+                    // path components are part of the same subpath (i == j)
+                    if (!(i == j && !both && crossing_points[p].sign * geom_sign > 0)) {
+                        std::swap(i, j);
+                        std::swap(ti, tj);
+                        std::swap(flag_i, flag_j);
+                    }
+                }
+                if (i0_is_under){
+                    if ( prop_to_stroke_width.get_value() ) {
+                        if (inverse_width) {
+                            width *= gstroke_widths[j];
+                        }
+                        else {
+                            width *= gstroke_widths[i];
+                        }
+                    }
+                    if (add_stroke_width.get_value() == "true") {
+                        width += gstroke_widths[i];
+                    }
+                    if (add_other_stroke_width.get_value() == "true") {
+                        width += gstroke_widths[j];
+                    }
+                    Interval hidden = findShadowedTime(gpaths[i0], flag_j, ti, width/2);
+                    double period  = size_nondegenerate(gpaths[i0]);
+                    if (hidden.max() > period ) hidden -= period;
+                    if (hidden.min()<0){
+                        dom = complementOf( Interval(0,hidden.max()) ,dom);
+                        dom = complementOf( Interval(hidden.min()+period, period) ,dom);
+                    }else{
+                        dom = complementOf(hidden,dom);
+                    }
+                    if (crossing_points[p].i == i0 && crossing_points[p].j == i0 && crossing_points[p].sign != 0 &&
+                        both) {
+                        hidden = findShadowedTime(gpaths[i0], flag_i, tj, width / 2);
+                        period = size_nondegenerate(gpaths[i0]);
+                        if (hidden.max() > period)
+                            hidden -= period;
+                        if (hidden.min() < 0) {
+                            dom = complementOf(Interval(0, hidden.max()), dom);
+                            dom = complementOf(Interval(hidden.min() + period, period), dom);
+                        }
+                        else {
+                            dom = complementOf(hidden, dom);
+                        }
+                    }
+                }
+            }
+        }
+
+        //If the all component is hidden, continue.
+        if (dom.empty()){
+            continue;
+        }
+
+        //If the current path is closed and the last/first point is still there, glue first and last piece.
+        unsigned beg_comp = 0, end_comp = dom.size();
+        if ( gpaths[i0].closed() && (dom.front().min() == 0) && (dom.back().max() == size_nondegenerate(gpaths[i0])) ) {
+            if ( dom.size() == 1){
+                path_out.push_back(gpaths[i0]);
+                continue;
+            }else{
+                // std::cout<<"fusing first and last component\n";
+                ++beg_comp;
+                --end_comp;
+                Geom::Path first = gpaths[i0].portion(dom.back());
+                //FIXME: stitching should not be necessary (?!?)
+                first.setStitching(true);
+                first.append(gpaths[i0].portion(dom.front()));
+                path_out.push_back(first);
+            }
+        }
+        for (unsigned comp = beg_comp; comp < end_comp; comp++){
+            assert(dom.at(comp).min() >=0 && dom.at(comp).max() <= size_nondegenerate(gpaths.at(i0)));
+            path_out.push_back(gpaths[i0].portion(dom.at(comp)));
+        }
+    }
+    return path_out;
+}
+
+
+
+//recursively collect gpaths and stroke widths (stolen from "sp-lpe_item.cpp").
+static void
+collectPathsAndWidths (SPLPEItem const *lpeitem, Geom::PathVector &paths, std::vector<double> &stroke_widths){
+    auto lpeitem_mutable = const_cast<SPLPEItem *>(lpeitem);
+
+    if (auto group = dynamic_cast<SPGroup *>(lpeitem_mutable)) {
+    	std::vector<SPItem*> item_list = sp_item_group_item_list(group);
+        for (auto subitem : item_list) {
+            if (SP_IS_LPE_ITEM(subitem)) {
+                collectPathsAndWidths(SP_LPE_ITEM(subitem), paths, stroke_widths);
+            }
+        }
+    } else if (auto shape = dynamic_cast<SPShape const *>(lpeitem)) {
+        SPCurve const *c = shape->curve();
+        if (c) {
+            Geom::PathVector subpaths = pathv_to_linear_and_cubic_beziers(c->get_pathvector());
+            for (const auto & subpath : subpaths){
+                paths.push_back(subpath);
+                //FIXME: do we have to be more careful when trying to access stroke width?
+                stroke_widths.push_back(lpeitem->style->stroke_width.computed);
+            }
+        }
+    }
+}
+
+
+void
+LPEKnot::doBeforeEffect (SPLPEItem const* lpeitem)
+{
+    using namespace Geom;
+    original_bbox(lpeitem);
+    
+    if (SP_IS_PATH(lpeitem)) {
+        supplied_path = SP_PATH(lpeitem)->curve()->get_pathvector();
+    }
+
+    gpaths.clear();
+    gstroke_widths.clear();
+
+    collectPathsAndWidths(lpeitem, gpaths, gstroke_widths);
+
+//     std::cout<<"\nPaths on input:\n";
+//     for (unsigned i=0; i<gpaths.size(); i++){
+//         for (unsigned ii=0; ii<gpaths[i].size(); ii++){
+//             std::cout << gpaths[i][ii].toSBasis()[Geom::X] <<"\n";
+//             std::cout << gpaths[i][ii].toSBasis()[Geom::Y] <<"\n";
+//             std::cout<<"--\n";
+//         }
+//     }
+                        
+    //std::cout<<"crossing_pts_vect: "<<crossing_points_vector.param_getSVGValue()<<".\n";
+    //std::cout<<"prop_to_stroke_width: "<<prop_to_stroke_width.param_getSVGValue()<<".\n";
+
+    LPEKnotNS::CrossingPoints old_crdata(crossing_points_vector.data());
+
+//     std::cout<<"\nVectorParam size:"<<crossing_points_vector.data().size()<<"\n";
+
+//     std::cout<<"\nOld crdata ("<<old_crdata.size()<<"): \n";
+//     for (unsigned toto=0; toto<old_crdata.size(); toto++){
+//         std::cout<<"(";
+//         std::cout<<old_crdata[toto].i<<",";
+//         std::cout<<old_crdata[toto].j<<",";
+//         std::cout<<old_crdata[toto].ni<<",";
+//         std::cout<<old_crdata[toto].nj<<",";
+//         std::cout<<old_crdata[toto].ti<<",";
+//         std::cout<<old_crdata[toto].tj<<",";
+//         std::cout<<old_crdata[toto].sign<<"),";
+//     }
+
+    //if ( old_crdata.size() > 0 ) std::cout<<"first crossing sign = "<<old_crdata[0].sign<<".\n";
+    //else std::cout<<"old data is empty!!\n";
+    crossing_points = LPEKnotNS::CrossingPoints(gpaths);
+//     std::cout<<"\nNew crdata ("<<crossing_points.size()<<"): \n";
+//     for (unsigned toto=0; toto<crossing_points.size(); toto++){
+//         std::cout<<"(";
+//         std::cout<<crossing_points[toto].i<<",";
+//         std::cout<<crossing_points[toto].j<<",";
+//         std::cout<<crossing_points[toto].ni<<",";
+//         std::cout<<crossing_points[toto].nj<<",";
+//         std::cout<<crossing_points[toto].ti<<",";
+//         std::cout<<crossing_points[toto].tj<<",";
+//         std::cout<<crossing_points[toto].sign<<"),";
+//     }
+    crossing_points.inherit_signs(old_crdata);
+
+    // Don't write to XML here, only store it in the param itself. Will be written to SVG later
+    crossing_points_vector.param_setValue(crossing_points.to_vector());
+
+    updateSwitcher();
+}
+
+void
+LPEKnot::addCanvasIndicators(SPLPEItem const */*lpeitem*/, std::vector<Geom::PathVector> &hp_vec)
+{
+    using namespace Geom;
+    double r = switcher_size*.1;
+    char const * svgd;
+    //TODO: use a nice path!
+    if ( (selectedCrossing >= crossing_points.size()) || (crossing_points[selectedCrossing].sign > 0) ) {
+        //svgd = "M -10,0 A 10 10 0 1 0 0,-10 l  5,-1 -1,2";
+        svgd = "m -7.07,7.07 c 3.9,3.91 10.24,3.91 14.14,0 3.91,-3.9 3.91,-10.24 0,-14.14 -3.9,-3.91 -10.24,-3.91 -14.14,0 l 2.83,-4.24 0.7,2.12";
+    } else if (crossing_points[selectedCrossing].sign < 0) {
+        //svgd = "M  10,0 A 10 10 0 1 1 0,-10 l -5,-1  1,2";
+        svgd = "m 7.07,7.07 c -3.9,3.91 -10.24,3.91 -14.14,0 -3.91,-3.9 -3.91,-10.24 0,-14.14 3.9,-3.91 10.24,-3.91 14.14,0 l -2.83,-4.24 -0.7,2.12";
+    } else {
+        //svgd = "M 10,0 A 10 10 0 1 0 -10,0 A 10 10 0 1 0 10,0 ";
+        svgd = "M 10,0 C 10,5.52 5.52,10 0,10 -5.52,10 -10,5.52 -10,0 c 0,-5.52 4.48,-10 10,-10 5.52,0 10,4.48 10,10 z";
+    }
+    PathVector pathv = sp_svg_read_pathv(svgd);
+    pathv *= Affine(r,0,0,r,0,0) * Translate(switcher);
+    hp_vec.push_back(pathv);
+}
+
+void LPEKnot::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
+{
+    KnotHolderEntity *e = new KnotHolderEntityCrossingSwitcher(this);
+    e->create(nullptr, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:CrossingSwitcher",
+              _("Drag to select a crossing, click to flip it, Shift + click to change all crossings, Ctrl + click to "
+                "reset and change all crossings"));
+    knotholder->add(e);
+};
+
+
+void
+KnotHolderEntityCrossingSwitcher::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint /*state*/)
+{
+    LPEKnot* lpe = dynamic_cast<LPEKnot *>(_effect);
+
+    lpe->selectedCrossing = idx_of_nearest(lpe->crossing_points,p);
+    lpe->updateSwitcher();
+    // FIXME: this should not directly ask for updating the item. It should write to SVG, which triggers updating.
+    sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), false, true);
+}
+
+Geom::Point
+KnotHolderEntityCrossingSwitcher::knot_get() const
+{
+    LPEKnot const *lpe = dynamic_cast<LPEKnot const*>(_effect);
+    return lpe->switcher;
+}
+
+void
+KnotHolderEntityCrossingSwitcher::knot_click(guint state)
+{
+    LPEKnot* lpe = dynamic_cast<LPEKnot *>(_effect);
+    unsigned s = lpe->selectedCrossing;
+    if (s < lpe->crossing_points.size()){
+        if (state & GDK_SHIFT_MASK){
+            for (unsigned p = 0; p < lpe->crossing_points.size(); p++) {
+                lpe->crossing_points[p].sign = ((lpe->crossing_points[p].sign + 2) % 3) - 1;
+            }
+        }
+        else if (state & GDK_CONTROL_MASK) {
+            int sign = lpe->crossing_points[s].sign;
+            for (unsigned p = 0; p < lpe->crossing_points.size(); p++) {
+                lpe->crossing_points[p].sign = ((sign + 2) % 3) - 1;
+            }
+        }else{
+            int sign = lpe->crossing_points[s].sign;
+            lpe->crossing_points[s].sign = ((sign+2)%3)-1;
+            //std::cout<<"crossing set to"<<lpe->crossing_points[s].sign<<".\n";
+        }
+        lpe->crossing_points_vector.param_set_and_write_new_value(lpe->crossing_points.to_vector());
+        DocumentUndo::done(lpe->getSPDoc(), _("Change knot crossing"), INKSCAPE_ICON("dialog-path-effects"));
+
+        // FIXME: this should not directly ask for updating the item. It should write to SVG, which triggers updating.
+//        sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), false, true);
+    }
+}
+
+
+/* ######################## */
+
+} // namespace LivePathEffect
+} // namespace Inkscape
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
+