src/live_effects/lpe-knot.cpp

	lpe-knot.cpp revision 0659728fce99e2f7abfe52bebf59b26b077512b4
/** @file
 * @brief LPE knot effect implementation
 */
/* Authors:
 *   Jean-Francois Barraud <jf.barraud@gmail.com>
 *
 * Copyright (C) 2007 Authors
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include "sp-shape.h"
#include "sp-path.h"
#include "display/curve.h"
#include "live_effects/lpe-knot.h"
#include "svg/svg.h"
#include "style.h"

#include <2geom/sbasis-to-bezier.h>
#include <2geom/sbasis.h>
#include <2geom/d2.h>
#include <2geom/d2-sbasis.h>
#include <2geom/path.h>
//#include <2geom/crossing.h>
#include <2geom/bezier-to-sbasis.h>
#include <2geom/basic-intersection.h>
#include <2geom/exception.h>

// for change crossing undo
#include "verbs.h"
#include "document.h"

#include <exception>

namespace Inkscape {
namespace LivePathEffect {

class KnotHolderEntityCrossingSwitcher : public LPEKnotHolderEntity
{
public:
    virtual ~KnotHolderEntityCrossingSwitcher() {}

    virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state);
    virtual Geom::Point knot_get();
    virtual void knot_click(guint state);
};


//---------------------------------------------------------------------------
//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;
    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 (unsigned i = 0; i<domain.size(); i++){
        boost::optional<Geom::Interval> I1i = intersect(domain.at(i),I1);
        if (I1i && !I1i->isSingular()) ret.push_back(I1i.get());
        boost::optional<Geom::Interval> I2i = intersect(domain.at(i),I2);
        if (I2i && !I2i->isSingular()) ret.push_back(I2i.get());
    }
    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, B = A+6*width*T;

    Matrix mat = from_basis( T, N, pt_and_dir[0] );
    mat = mat.inverse();
    Path p = patha * mat;

    std::vector<double> times;

    //TODO: explore the path fwd/backward from ta (worth?)
    for (unsigned i=0; i<patha.size(); 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 (unsigned k=0; k<times_i.size(); 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 = patha.size();
    double period = patha.size();//hm... Should this be patha.size()+1?
    if (times.size()>0){
        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(std::vector<Geom::Path> 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<paths[i].size(); ii++){
            for( unsigned j=i; j<paths.size(); j++){
                for( unsigned jj=(i==j?ii:0); jj<paths[j].size(); 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 (unsigned k=0; k<times.size(); k++){
                        //std::cout<<"intersection "<<i<<"["<<ii<<"]("<<times[k].first<<")= "<<j<<"["<<jj<<"]("<<times[k].second<<")\n";
                        if (times[k].first == times[k].first && times[k].second == times[k].second ){//is this the way to test NaN?
                            double zero = 1e-4;
                            if ( i==j && fabs(times[k].first+ii - times[k].second-jj)<=zero ){//this is just end=start of successive curves in a path.
                                continue;
                            }
                            if ( i==j && ii == 0 && jj==paths[i].size()-1 &&
                                 paths[i].closed() &&
                                 fabs(times[k].first) <= zero &&
                                 fabs(times[k].second - 1) <= zero ){//this is just end=start of a closed path.
                                continue;
                            }
                            CrossingPoint cp;
                            cp.pt = paths[i][ii].pointAt(times[k].first);
                            cp.sign = 1;
                            cp.i = i;
                            cp.j = j;
                            cp.ni = 0; cp.nj=0;//not set yet
                            cp.ti = times[k].first + ii;
                            cp.tj = times[k].second + jj;
                            push_back(cp);
                        }else{
                            std::cout<<"ooops: find_(self)_intersections returned NaN:";
                            //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 ( std::map < double, unsigned >::iterator m=cuts.begin(); m!=cuts.end(); m++ ){
            if ( (*this)[m->second].i == i && (*this)[m->second].ti == m->first ){
                (*this)[m->second].ni = count;
            }else{
                (*this)[m->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();
}

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(_("Fixed width"), _("Size of hidden region of lower string"), "interruption_width", &wr, this, 3),
    prop_to_stroke_width(_("In units of stroke width"), _("Consider 'Interruption width' as a ratio of stroke width"), "prop_to_stroke_width", &wr, this, true),
    add_stroke_width(_("Stroke width"), _("Add the stroke width to the interruption size"), "add_stroke_width", &wr, this, true),
    add_other_stroke_width(_("Crossing path stroke width"), _("Add crossed stroke width to the interruption size"), "add_other_stroke_width", &wr, this, true),
    switcher_size(_("Switcher size"), _("Orientation indicator/switcher size"), "switcher_size", &wr, this, 15),
    crossing_points_vector(_("Crossing Signs"), _("Crossings signs"), "crossing_points_vector", &wr, this),
    gpaths(),gstroke_widths()
{
    // register all your parameters here, so Inkscape knows which parameters this effect has:
    registerParameter( dynamic_cast<Parameter *>(&interruption_width) );
    registerParameter( dynamic_cast<Parameter *>(&prop_to_stroke_width) );
    registerParameter( dynamic_cast<Parameter *>(&add_stroke_width) );
    registerParameter( dynamic_cast<Parameter *>(&add_other_stroke_width) );
    registerParameter( dynamic_cast<Parameter *>(&switcher_size) );
    registerParameter( dynamic_cast<Parameter *>(&crossing_points_vector) );

    registerKnotHolderHandle(new KnotHolderEntityCrossingSwitcher(), _("Drag to select a crossing, click to flip it"));
    crossing_points = LPEKnotNS::CrossingPoints();
    selectedCrossing = 0;
    switcher = Geom::Point(0,0);
}

LPEKnot::~LPEKnot()
{

}

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";
        //TODO: is there a way to properly hide the helper.
        //switcher = Geom::Point(Geom::infinity(),Geom::infinity());
        switcher = Geom::Point(1e10,1e10);
    }
}

std::vector<Geom::Path>
LPEKnot::doEffect_path (std::vector<Geom::Path> const &path_in)
{
    using namespace Geom;
    std::vector<Geom::Path> path_out;

    if (gpaths.size()==0){
        return path_in;
    }

    for (unsigned comp=0; comp<path_in.size(); comp++){

        //find the relevant path component in gpaths (required to allow groups!)
        //Q: do we always recieve the group members in the same order? can we rest on that?
        unsigned i0 = 0;
        for (i0=0; i0<gpaths.size(); i0++){
            if (path_in[comp]==gpaths[i0]) break;
        }
        if (i0 == gpaths.size() ) {THROW_EXCEPTION("lpe-knot error: group member not recognized");}// this should not happen...

        std::vector<Interval> dom;
        dom.push_back(Interval(0.,gpaths[i0].size()));
        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 == gpaths[i].size() ) { curveidx--; t = 1.;}
                assert(curveidx >= 0 && curveidx < gpaths[i].size());
                std::vector<Point> flag_i = gpaths[i][curveidx].pointAndDerivatives(t,1);

                t = modf(tj, &curveidx);
                if(curveidx == gpaths[j].size() ) { curveidx--; t = 1.;}
                assert(curveidx >= 0 && curveidx < gpaths[j].size());
                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;
                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){
                        std::swap( i, j);
                        std::swap(ti, tj);
                        std::swap(flag_i,flag_j);
                        i0_is_under = true;
                    }
                }
                if (i0_is_under){
                    double width = interruption_width;
                    if ( prop_to_stroke_width.get_value() ) {
                        width *= gstroke_widths[i];
                    }
                    if ( add_stroke_width.get_value() ) {
                        width += gstroke_widths[i];
                    }
                    if ( add_other_stroke_width.get_value() ) {
                        width += gstroke_widths[j];
                    }
                    Interval hidden = findShadowedTime(gpaths[i0], flag_j, ti, width/2);
                    double period  = gpaths[i0].size();//hm... Should this be gpaths[i0].size()+1?
                    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.size() == 0){
            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() ==  gpaths[i0].size() ){
            if ( dom.size() == 1){
                path_out.push_back(gpaths[i0]);
                continue;
            }else{
//                std::cout<<"fusing first and last component\n";
                beg_comp++;
                end_comp--;
                Path first = gpaths[i0].portion(dom.back());
                //FIXME: STITCH_DISCONTINUOUS should not be necessary (?!?)
                first.append(gpaths[i0].portion(dom.front()), Path::STITCH_DISCONTINUOUS);
                path_out.push_back(first);
            }
        }
        for (unsigned comp = beg_comp; comp < end_comp; comp++){
            assert(dom.at(comp).min() >=0 and dom.at(comp).max() <= gpaths.at(i0).size());
            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").
void collectPathsAndWidths (SPLPEItem const *lpeitem, std::vector<Geom::Path> &paths, std::vector<double> &stroke_widths){
    if (SP_IS_GROUP(lpeitem)) {
        GSList const *item_list = sp_item_group_item_list(SP_GROUP(lpeitem));
        for ( GSList const *iter = item_list; iter; iter = iter->next ) {
            SPObject *subitem = static_cast<SPObject *>(iter->data);
            if (SP_IS_LPE_ITEM(subitem)) {
                collectPathsAndWidths(SP_LPE_ITEM(subitem), paths, stroke_widths);
            }
        }
    }
    else if (SP_IS_SHAPE(lpeitem)) {
        SPCurve * c = NULL;
        if (SP_IS_PATH(lpeitem)) {
            c = sp_path_get_curve_for_edit(SP_PATH(lpeitem));
        } else {
            c = sp_shape_get_curve(SP_SHAPE(lpeitem));
        }
        if (c) {
            Geom::PathVector subpaths = c->get_pathvector();
            for (unsigned i=0; i<subpaths.size(); i++){
                paths.push_back(subpaths[i]);
                //FIXME: do we have to be more carefull when trying to access stroke width?
                stroke_widths.push_back(SP_ITEM(lpeitem)->style->stroke_width.computed);
            }
        }
    }
}


void
LPEKnot::doBeforeEffect (SPLPEItem *lpeitem)
{
    using namespace Geom;
    original_bbox(lpeitem);

    gpaths = std::vector<Geom::Path>();
    gstroke_widths = std::vector<double>();
    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);
    crossing_points_vector.param_set_and_write_new_value(crossing_points.to_vector());
    updateSwitcher();
}


static LPEKnot *
get_effect(SPItem *item)
{
    Effect *effect = sp_lpe_item_get_current_lpe(SP_LPE_ITEM(item));
    if (effect->effectType() != KNOT) {
        g_print ("Warning: Effect is not of type LPEKnot!\n");
        return NULL;
    }
    return static_cast<LPEKnot *>(effect);
}

void
LPEKnot::addCanvasIndicators(SPLPEItem */*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 *= Matrix(r,0,0,r,0,0);
    pathv+=switcher;
    hp_vec.push_back(pathv);
}

void
KnotHolderEntityCrossingSwitcher::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint /*state*/)
{
    LPEKnot* lpe = get_effect(item);

    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()
{
    LPEKnot* lpe = get_effect(item);
    return snap_knot_position(lpe->switcher);
}

void
KnotHolderEntityCrossingSwitcher::knot_click(guint state)
{
    LPEKnot* lpe = get_effect(item);
    unsigned s = lpe->selectedCrossing;
    if (s < lpe->crossing_points.size()){
        if (state & GDK_SHIFT_MASK){
            lpe->crossing_points[s].sign = 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());
        sp_document_done(lpe->getSPDoc(), SP_VERB_DIALOG_LIVE_PATH_EFFECT, /// @todo Is this the right verb?
                 _("Change knot crossing"));

        // 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:encoding=utf-8:textwidth=99 :