path: root/src/live_effects/lpe-taperstroke.cpp

/**
 * @file
 * Taper Stroke path effect, provided as an alternative to Power Strokes
 * for otherwise constant-width paths.
 *
 * Authors:
 *   Liam P White <inkscapebrony@gmail.com>
 *
 * Copyright (C) 2014 Authors
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include "live_effects/lpe-taperstroke.h"

#include <2geom/path.h>
#include <2geom/shape.h>
#include <2geom/path.h>
#include <2geom/circle.h>
#include <2geom/sbasis-to-bezier.h>
#include "pathoutlineprovider.h"
#include "display/curve.h"
#include "sp-shape.h"
#include "style.h"
#include "xml/repr.h"
#include "sp-paint-server.h"
#include "svg/svg-color.h"
#include "desktop-style.h"
#include "svg/css-ostringstream.h"
#include "svg/svg.h"

//#include <glibmm/i18n.h>

#include "knot-holder-entity.h"
#include "knotholder.h"

namespace Inkscape {
namespace LivePathEffect {

namespace TpS {
    class KnotHolderEntityAttachBegin : public LPEKnotHolderEntity {
    public:
        KnotHolderEntityAttachBegin(LPETaperStroke * effect) : LPEKnotHolderEntity(effect) {}
        virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state);
        virtual Geom::Point knot_get() const;
    };
    
    class KnotHolderEntityAttachEnd : public LPEKnotHolderEntity {
    public:
        KnotHolderEntityAttachEnd(LPETaperStroke * effect) : LPEKnotHolderEntity(effect) {}
        virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state);
        virtual Geom::Point knot_get() const;
    };
} // TpS

static const Util::EnumData<unsigned> JoinType[] = {
    {LINEJOIN_STRAIGHT,         N_("Beveled"),          "bevel"},
    {LINEJOIN_ROUND,            N_("Rounded"),          "round"},
    {LINEJOIN_REFLECTED,        N_("Reflected"),        "reflected"},
    {LINEJOIN_POINTY,           N_("Miter"),            "miter"},
    {LINEJOIN_EXTRAPOLATED,     N_("Extrapolated"),     "extrapolated"}
};

static const Util::EnumDataConverter<unsigned> JoinTypeConverter(JoinType, sizeof (JoinType)/sizeof(*JoinType));

LPETaperStroke::LPETaperStroke(LivePathEffectObject *lpeobject) :
    Effect(lpeobject),
    line_width(_("Stroke width"), _("The (non-tapered) width of the path"), "stroke_width", &wr, this, 3),
    attach_start(_("Start offset"), _("Taper distance from path start"), "attach_start", &wr, this, 0.2),
    attach_end(_("End offset"), _("The ending position of the taper"), "end_offset", &wr, this, 0.2),
    smoothing(_("Taper smoothing"), _("Amount of smoothing to apply to the tapers"), "smoothing", &wr, this, 0.5),
    join_type(_("Join type"), _("Join type for non-smooth nodes"), "jointype", JoinTypeConverter, &wr, this, LINEJOIN_EXTRAPOLATED),
    miter_limit(_("Miter limit"), _("Limit for miter joins"), "miter_limit", &wr, this, 30.)
{
    show_orig_path = true;
    _provides_knotholder_entities = true;

    attach_start.param_set_digits(3);
    attach_end.param_set_digits(3);


    registerParameter( dynamic_cast<Parameter *>(&line_width) );
    registerParameter( dynamic_cast<Parameter *>(&attach_start) );
    registerParameter( dynamic_cast<Parameter *>(&attach_end) );
    registerParameter( dynamic_cast<Parameter *>(&smoothing) );
    registerParameter( dynamic_cast<Parameter *>(&join_type) );
    registerParameter( dynamic_cast<Parameter *>(&miter_limit) );
}

LPETaperStroke::~LPETaperStroke()
{

}

//from LPEPowerStroke -- sets fill if stroke color because we will
//be converting to a fill to make the new join.

void LPETaperStroke::doOnApply(SPLPEItem const* lpeitem)
{
    if (SP_IS_SHAPE(lpeitem)) {
        SPLPEItem* item = const_cast<SPLPEItem*>(lpeitem);
        double width = (lpeitem && lpeitem->style) ? lpeitem->style->stroke_width.computed : 1.;

        SPCSSAttr *css = sp_repr_css_attr_new ();
        if (lpeitem->style->stroke.isSet()) {
            if (lpeitem->style->stroke.isPaintserver()) {
                SPPaintServer * server = lpeitem->style->getStrokePaintServer();
                if (server) {
                    Glib::ustring str;
                    str += "url(#";
                    str += server->getId();
                    str += ")";
                    sp_repr_css_set_property (css, "fill", str.c_str());
                }
            } else if (lpeitem->style->stroke.isColor()) {
                gchar c[64];
                sp_svg_write_color (c, sizeof(c), lpeitem->style->stroke.value.color.toRGBA32(SP_SCALE24_TO_FLOAT(lpeitem->style->stroke_opacity.value)));
                sp_repr_css_set_property (css, "fill", c);
            } else {
                sp_repr_css_set_property (css, "fill", "none");
            }
        } else {
            sp_repr_css_unset_property (css, "fill");
        }

        sp_repr_css_set_property(css, "stroke", "none");

        sp_desktop_apply_css_recursive(item, css, true);
        sp_repr_css_attr_unref (css);

        line_width.param_set_value(width);
    } else {
        g_warning("LPE Join Type can only be applied to paths (not groups).");
    }
}

//from LPEPowerStroke -- sets stroke color from existing fill color

void LPETaperStroke::doOnRemove(SPLPEItem const* lpeitem)
{

    if (SP_IS_SHAPE(lpeitem)) {
        //TODO: make it getobjbyrepr instead of const_cast because this can cause
        //undefined behavior
        SPLPEItem *item = const_cast<SPLPEItem*>(lpeitem);

        SPCSSAttr *css = sp_repr_css_attr_new ();
        if (lpeitem->style->fill.isSet()) {
            if (lpeitem->style->fill.isPaintserver()) {
                SPPaintServer * server = lpeitem->style->getFillPaintServer();
                if (server) {
                    Glib::ustring str;
                    str += "url(#";
                    str += server->getId();
                    str += ")";
                    sp_repr_css_set_property (css, "stroke", str.c_str());
                }
            } else if (lpeitem->style->fill.isColor()) {
                gchar c[64];
                sp_svg_write_color (c, sizeof(c), lpeitem->style->stroke.value.color.toRGBA32(SP_SCALE24_TO_FLOAT(lpeitem->style->stroke_opacity.value)));
                sp_repr_css_set_property (css, "stroke", c);
            } else {
                sp_repr_css_set_property (css, "stroke", "none");
            }
        } else {
            sp_repr_css_unset_property (css, "stroke");
        }

        Inkscape::CSSOStringStream os;
        os << fabs(line_width);
        sp_repr_css_set_property (css, "stroke-width", os.str().c_str());

        sp_repr_css_set_property(css, "fill", "none");

        sp_desktop_apply_css_recursive(item, css, true);
        sp_repr_css_attr_unref (css);
        item->updateRepr();
    }
}

//actual effect impl here

Geom::Path return_at_first_cusp (Geom::Path const & path_in, double smooth_tolerance = 0.05)
{
    Geom::Path path_out = Geom::Path();

    for (unsigned i = 0; i < path_in.size(); i++) {
        path_out.append(path_in[i]);
        if (path_in.size() == 1)
            break;

        //determine order of curve
        int order = Outline::bezierOrder(&path_in[i]);

        Geom::Point start_point;
        Geom::Point cross_point = path_in[i].finalPoint();
        Geom::Point end_point;

        g_assert(path_in[i].finalPoint() == path_in[i+1].initialPoint());

        //can you tell that the following expressions have been shaped by
        //repeated compiler errors? ;)
        switch (order) {
        case 3:
            start_point = (static_cast<const Geom::CubicBezier*>(&path_in[i]))->operator[] (2);
            //major league b***f***ing
            if (are_near(start_point, cross_point, 0.0000001)) {
                start_point = (static_cast<const Geom::CubicBezier*>(&path_in[i]))->operator[] (1);
            }
            break;
        case 2:
            //this never happens
            start_point = (static_cast<const Geom::QuadraticBezier*>(&path_in[i]))->operator[] (1);
            break;
        case 1:
        default:
            start_point = path_in[i].initialPoint();
        }

        order = Outline::bezierOrder(&path_in[i+1]);

        switch (order) {
        case 3:
            end_point = (static_cast<const Geom::CubicBezier*>(&path_in[i+1]))->operator[] (1);
            if (are_near(end_point, cross_point, 0.0000001)) {
                end_point = (static_cast<const Geom::CubicBezier*>(&path_in[i+1]))->operator[] (2);
            }
            break;
        case 2:
            end_point = (static_cast<const Geom::QuadraticBezier*>(&path_in[i+1]))->operator[] (1);
            break;
        case 1:
        default:
            end_point = path_in[i+1].finalPoint();
        }

        //clearly it's collinear if two occupy the same point
        g_assert(!are_near(start_point, cross_point, 0.0000001));
        g_assert(!are_near(cross_point, end_point,   0.0000001));
        g_assert(!are_near(start_point, end_point,   0.0000001));

        if (!are_collinear(start_point, cross_point, end_point, smooth_tolerance))
            break;
    }
    return path_out;
}

Geom::Piecewise<Geom::D2<Geom::SBasis> > stretch_along(Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2_in, Geom::Path pattern, double width);

//references to pointers, because magic
void subdivideCurve(const Geom::Curve * curve_in, Geom::Coord t, Geom::Curve *& val_first, Geom::Curve *& val_second);

Geom::PathVector LPETaperStroke::doEffect_path(Geom::PathVector const& path_in)
{
    Geom::Path first_cusp = return_at_first_cusp(path_in[0]);
    Geom::Path last_cusp = return_at_first_cusp(path_in[0].reverse());

    bool zeroStart = false;
    bool zeroEnd = false;
    //there is a pretty good chance that people will try to drag the knots
    //on top of each other, so block it

    unsigned size = path_in[0].size();
    if (size == first_cusp.size()) {
        //check to see if the knots were dragged over each other
        //if so, reset the end offset
        if ( attach_start >= (size - attach_end) ) {
            attach_end.param_set_value( size - attach_start );
        }
    }

    //don't let it be zero
    if (attach_start <= 0.00000001) {
        attach_start.param_set_value( 0.00000001 );
        zeroStart = true;
    }
    if (attach_end <= 0.00000001) {
        attach_end.param_set_value( 0.00000001 );
        zeroEnd = true;
    }

    //don't let it be integer
    if (double(unsigned(attach_start)) == attach_start) {
        attach_start.param_set_value(attach_start - 0.00001);
    }
    if (double(unsigned(attach_end)) == attach_end) {
        attach_end.param_set_value(attach_end -     0.00001);
    }

    unsigned allowed_start = first_cusp.size();
    unsigned allowed_end = last_cusp.size();

    //don't let the knots be farther than they are allowed to be
    if ((unsigned)attach_start >= allowed_start) {
        attach_start.param_set_value((double)allowed_start - 0.00000001);
    }
    if ((unsigned)attach_end >= allowed_end) {
        attach_end.param_set_value((double)allowed_end - 0.00000001);
    }

    //remember, Path::operator () means get point at time t
    start_attach_point = first_cusp(attach_start);
    end_attach_point = last_cusp(attach_end);
    Geom::PathVector pathv_out;

    //the following function just splits it up into three pieces.
    pathv_out = doEffect_simplePath(path_in);

    //now for the actual tapering. We use a Pattern Along Path method to get this done.

    Geom::PathVector real_pathv;
    Geom::Path real_path;
    Geom::PathVector pat_vec;
    Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2;
    Geom::Path throwaway_path;

    if (!zeroStart) {
        //Construct the pattern (pat_str stands for pattern string) (yes, this is easier, trust me)
        std::stringstream pat_str;
        pat_str << "M 1,0 C " << 1 - (double)smoothing << ",0 0,0.5 0,0.5 0,0.5 " << 1 - (double)smoothing << ",1 1,1";

        pat_vec = sp_svg_read_pathv(pat_str.str().c_str());
        pwd2.concat(stretch_along(pathv_out[0].toPwSb(), pat_vec[0], -fabs(line_width)));
        throwaway_path = Geom::path_from_piecewise(pwd2, 0.001)[0];

        real_path.append(throwaway_path);
    }
    //append the outside outline of the path (with direction)
    throwaway_path = Outline::PathOutsideOutline(pathv_out[1],
                     -fabs(line_width), static_cast<LineJoinType>(join_type.get_value()), miter_limit);

    real_path.append(throwaway_path, Geom::Path::STITCH_DISCONTINUOUS);

    if (!zeroEnd) {
        //append the ending taper
        std::stringstream pat_str_1;
        pat_str_1 << "M 0,0 0,1 C " << (double)smoothing << ",1 1,0.5 1,0.5 1,0.5 " << double(smoothing) << ",0 0,0";
        pat_vec = sp_svg_read_pathv(pat_str_1.str().c_str());

        pwd2 = Geom::Piecewise<Geom::D2<Geom::SBasis> > ();
        pwd2.concat(stretch_along(pathv_out[2].toPwSb(), pat_vec[0], -fabs(line_width)));

        throwaway_path = Geom::path_from_piecewise(pwd2, 0.001)[0];
        real_path.append(throwaway_path, Geom::Path::STITCH_DISCONTINUOUS);
    }
    //append the inside outline of the path (against direction)
    throwaway_path = Outline::PathOutsideOutline(pathv_out[1].reverse(),
                     -fabs(line_width), static_cast<LineJoinType>(join_type.get_value()), miter_limit);

    real_path.append(throwaway_path, Geom::Path::STITCH_DISCONTINUOUS);
    real_path.appendNew<Geom::LineSegment>(real_path.initialPoint());

    real_path.close();
    
    real_pathv.push_back(real_path);

    return real_pathv;
}

//in all cases, this should return a PathVector with three elements.
Geom::PathVector LPETaperStroke::doEffect_simplePath(Geom::PathVector const & path_in)
{
    unsigned size = path_in[0].size();

    //do subdivision and get out
    unsigned loc = (unsigned)attach_start;
    Geom::Curve * curve_start = path_in[0] [loc].duplicate();

    std::vector<Geom::Path> pathv_out;
    Geom::Path path_out = Geom::Path();

    Geom::Path trimmed_start = Geom::Path();
    Geom::Path trimmed_end = Geom::Path();

    for (unsigned i = 0; i < loc; i++) {
        trimmed_start.append(path_in[0] [i]);
    }


    //this is pretty annoying
    //previously I wrote a function for this but it wasted a lot of time
    //so I optimized it back into here.
    unsigned order = Outline::bezierOrder(curve_start);
    switch (order) {
    case 3: {
        Geom::CubicBezier *cb = static_cast<Geom::CubicBezier * >(curve_start);
        std::pair<Geom::CubicBezier, Geom::CubicBezier> cb_pair = cb->subdivide((attach_start - loc));
        trimmed_start.append(cb_pair.first);
        curve_start = cb_pair.second.duplicate(); //goes out of scope
        break;
    }
    case 2: {
        Geom::QuadraticBezier *qb = static_cast<Geom::QuadraticBezier * >(curve_start);
        std::pair<Geom::QuadraticBezier, Geom::QuadraticBezier> qb_pair = qb->subdivide((attach_start - loc));
        trimmed_start.append(qb_pair.first);
        curve_start = qb_pair.second.duplicate();
        break;
    }
    case 1: {
        Geom::BezierCurveN<1> *lb = static_cast<Geom::BezierCurveN<1> * >(curve_start);
        std::pair<Geom::BezierCurveN<1>, Geom::BezierCurveN<1> > lb_pair = lb->subdivide((attach_start - loc));
        trimmed_start.append(lb_pair.first);
        curve_start = lb_pair.second.duplicate();
        break;
    }
    }

    //special case: path is one segment long
    //special case: what if the two knots occupy the same segment?
    if ((size == 1) || ( size - unsigned(attach_end) - 1 == loc )) {
        Geom::Coord t = Geom::nearest_point(end_attach_point, *curve_start);

        //it is just a dumb segment
        //we have to do some shifting here because the value changed when we reduced the length
        //of the previous segment.

        order = Outline::bezierOrder(curve_start);
        switch (order) {
        case 3: {
            Geom::CubicBezier *cb = static_cast<Geom::CubicBezier * >(curve_start);
            std::pair<Geom::CubicBezier, Geom::CubicBezier> cb_pair = cb->subdivide(t);
            trimmed_end.append(cb_pair.second);
            curve_start = cb_pair.first.duplicate();
            break;
        }
        case 2: {
            Geom::QuadraticBezier *qb = static_cast<Geom::QuadraticBezier * >(curve_start);
            std::pair<Geom::QuadraticBezier, Geom::QuadraticBezier> qb_pair = qb->subdivide(t);
            trimmed_end.append(qb_pair.second);
            curve_start = qb_pair.first.duplicate();
            break;
        }
        case 1: {
            Geom::BezierCurveN<1> *lb = static_cast<Geom::BezierCurveN<1> * >(curve_start);
            std::pair<Geom::BezierCurveN<1>, Geom::BezierCurveN<1> > lb_pair = lb->subdivide(t);
            trimmed_end.append(lb_pair.second);
            curve_start = lb_pair.first.duplicate();
            break;
        }
        }

        for (unsigned j = (size - attach_end) + 1; j < size; j++) {
            trimmed_end.append(path_in[0] [j]);
        }

        path_out.append(*curve_start);
        pathv_out.push_back(trimmed_start);
        pathv_out.push_back(path_out);
        pathv_out.push_back(trimmed_end);
        return pathv_out;
    }

    pathv_out.push_back(trimmed_start);

    //append almost all of the rest of the path, ignore the curves that the knot is past (we'll get to it in a minute)
    path_out.append(*curve_start);

    for (unsigned k = loc + 1; k < (size - unsigned(attach_end)) - 1; k++) {
        path_out.append(path_in[0] [k]);
    }

    //deal with the last segment in a very similar fashion to the first
    loc = size - attach_end;

    Geom::Curve * curve_end = path_in[0] [loc].duplicate();

    Geom::Coord t = Geom::nearest_point(end_attach_point, *curve_end);

    order = Outline::bezierOrder(curve_end);
    switch (order) {
    case 3: {
        Geom::CubicBezier *cb = static_cast<Geom::CubicBezier * >(curve_end);
        std::pair<Geom::CubicBezier, Geom::CubicBezier> cb_pair = cb->subdivide(t);
        trimmed_end.append(cb_pair.second);
        curve_end = cb_pair.first.duplicate();
        break;
    }
    case 2: {
        Geom::QuadraticBezier *qb = static_cast<Geom::QuadraticBezier * >(curve_end);
        std::pair<Geom::QuadraticBezier, Geom::QuadraticBezier> qb_pair = qb->subdivide(t);
        trimmed_end.append(qb_pair.second);
        curve_end = qb_pair.first.duplicate();
        break;
    }
    case 1: {
        Geom::BezierCurveN<1> *lb = static_cast<Geom::BezierCurveN<1> * >(curve_end);
        std::pair<Geom::BezierCurveN<1>, Geom::BezierCurveN<1> > lb_pair = lb->subdivide(t);
        trimmed_end.append(lb_pair.second);
        curve_end = lb_pair.first.duplicate();
        break;
    }
    }

    for (unsigned j = (size - attach_end) + 1; j < size; j++) {
        trimmed_end.append(path_in[0] [j]);
    }

    path_out.append(*curve_end);
    pathv_out.push_back(path_out);

    pathv_out.push_back(trimmed_end);

    if (curve_end) delete curve_end;
    if (curve_start) delete curve_start;
    return pathv_out;
}


//most of the below code is verbatim from Pattern Along Path. However, it needed a little
//tweaking to get it to work right in this case.
Geom::Piecewise<Geom::D2<Geom::SBasis> > stretch_along(Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2_in, Geom::Path pattern, double prop_scale)
{
    using namespace Geom;

    // Don't allow empty path parameter:
    if ( pattern.empty() ) {
        return pwd2_in;
    }

    /* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */
    Piecewise<D2<SBasis> > output;
    std::vector<Geom::Piecewise<Geom::D2<Geom::SBasis> > > pre_output;

    D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(pattern.toPwSb());
    Piecewise<SBasis> x0 = Piecewise<SBasis>(patternd2[0]);
    Piecewise<SBasis> y0 = Piecewise<SBasis>(patternd2[1]);
    OptInterval pattBndsX = bounds_exact(x0);
    OptInterval pattBndsY = bounds_exact(y0);
    if (pattBndsX && pattBndsY) {
        x0 -= pattBndsX->min();
        y0 -= pattBndsY->middle();

        double xspace  = 0;
        double noffset = 0;
        double toffset = 0;
        /*if (prop_units.get_value() && pattBndsY){
            xspace  *= pattBndsX->extent();
            noffset *= pattBndsY->extent();
            toffset *= pattBndsX->extent();
        }*/

        //Prevent more than 90% overlap...
        if (xspace < -pattBndsX->extent()*.9) {
            xspace = -pattBndsX->extent()*.9;
        }

        y0+=noffset;

        std::vector<Geom::Piecewise<Geom::D2<Geom::SBasis> > > paths_in;
        paths_in = split_at_discontinuities(pwd2_in);

        for (unsigned idx = 0; idx < paths_in.size(); idx++) {
            Geom::Piecewise<Geom::D2<Geom::SBasis> > path_i = paths_in[idx];
            Piecewise<SBasis> x = x0;
            Piecewise<SBasis> y = y0;
            Piecewise<D2<SBasis> > uskeleton = arc_length_parametrization(path_i,2,.1);
            uskeleton = remove_short_cuts(uskeleton,.01);
            Piecewise<D2<SBasis> > n = rot90(derivative(uskeleton));
            n = force_continuity(remove_short_cuts(n,.1));

            int nbCopies = 0;
            double scaling = 1;
            nbCopies = 1;
            scaling = (uskeleton.domain().extent() - toffset)/pattBndsX->extent();

            double pattWidth = pattBndsX->extent() * scaling;

            if (scaling != 1.0) {
                x*=scaling;
            }
            if ( false ) {
                y*=(scaling*prop_scale);
            } else {
                if (prop_scale != 1.0) y *= prop_scale;
            }
            x += toffset;

            double offs = 0;
            for (int i=0; i<nbCopies; i++) {
                if (false) {
                    Geom::Piecewise<Geom::D2<Geom::SBasis> > output_piece = compose(uskeleton,x+offs)+y*compose(n,x+offs);
                    std::vector<Geom::Piecewise<Geom::D2<Geom::SBasis> > > splited_output_piece = split_at_discontinuities(output_piece);
                    pre_output.insert(pre_output.end(), splited_output_piece.begin(), splited_output_piece.end() );
                } else {
                    output.concat(compose(uskeleton,x+offs)+y*compose(n,x+offs));
                }
                offs+=pattWidth;
            }
        }
        /*if (false){
            pre_output = fuse_nearby_ends(pre_output, fuse_tolerance);
            for (unsigned i=0; i<pre_output.size(); i++){
                output.concat(pre_output[i]);
            }
        }*/
        return output;
    } else {
        return pwd2_in;
    }
}

void subdivideCurve(Geom::Curve * curve_in, Geom::Coord t, Geom::Curve *& val_first, Geom::Curve *& val_second)
{
    unsigned order = Outline::bezierOrder(curve_in);
    switch (order) {
    case 3: {
        Geom::CubicBezier *cb = static_cast<Geom::CubicBezier * >(curve_in);
        std::pair<Geom::CubicBezier, Geom::CubicBezier> cb_pair = cb->subdivide(t);
        //trimmed_start.append(cb_pair.first);
        val_first = cb_pair.first.duplicate();
        val_second = cb_pair.second.duplicate();
        break;
    }
    case 2: {
        Geom::QuadraticBezier *qb = static_cast<Geom::QuadraticBezier * >(curve_in);
        std::pair<Geom::QuadraticBezier, Geom::QuadraticBezier> qb_pair = qb->subdivide(t);
        //trimmed_start.append(qb_pair.first);
        val_first = qb_pair.first.duplicate();
        val_second = qb_pair.second.duplicate();
        break;
    }
    case 1: {
        Geom::BezierCurveN<1> *lb = static_cast<Geom::BezierCurveN<1> * >(curve_in);
        std::pair<Geom::BezierCurveN<1>, Geom::BezierCurveN<1> > lb_pair = lb->subdivide(t);
        //trimmed_start.append(lb_pair.first);
        val_first = lb_pair.first.duplicate();
        val_second = lb_pair.second.duplicate();
        break;
    }
    }
}


void LPETaperStroke::addKnotHolderEntities(KnotHolder *knotholder, SPDesktop *desktop, SPItem *item)
{
    {
        KnotHolderEntity *e = new TpS::KnotHolderEntityAttachBegin(this);
        e->create(  desktop, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                    _("Start point of the taper"), SP_KNOT_SHAPE_CIRCLE );
        knotholder->add(e);
    }
    {
        KnotHolderEntity *e = new TpS::KnotHolderEntityAttachEnd(this);
        e->create(	desktop, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN,
                    _("End point of the taper"), SP_KNOT_SHAPE_CIRCLE );
        knotholder->add(e);
    }
}

namespace TpS {
void KnotHolderEntityAttachBegin::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint state)
{
    using namespace Geom;

    LPETaperStroke* lpe = dynamic_cast<LPETaperStroke *>(_effect);

    Geom::Point const s = snap_knot_position(p, state);

    SPCurve *curve = SP_PATH(item)->get_curve_for_edit();
    Geom::PathVector pathv = curve->get_pathvector();
    Piecewise<D2<SBasis> > pwd2;
    Geom::Path p_in = return_at_first_cusp(pathv[0]);
    pwd2.concat(p_in.toPwSb());
    std::vector<Geom::Piecewise<Geom::D2<Geom::SBasis> > > pwd_vec = split_at_discontinuities(pwd2);

    double t0 = nearest_point(s, pwd_vec[0]);
    lpe->attach_start.param_set_value(t0);

    // 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);
}
void KnotHolderEntityAttachEnd::knot_set(Geom::Point const &p, Geom::Point const& /*origin*/, guint state)
{
    using namespace Geom;

    LPETaperStroke* lpe = dynamic_cast<LPETaperStroke *>(_effect);

    Geom::Point const s = snap_knot_position(p, state);

    SPCurve *curve = SP_PATH(item)->get_curve_for_edit();
    Geom::PathVector pathv = curve->get_pathvector();
    Piecewise<D2<SBasis> > pwd2;
    Geom::Path p_in = return_at_first_cusp(pathv[0].reverse());
    pwd2.concat(p_in.toPwSb());
    std::vector<Geom::Piecewise<Geom::D2<Geom::SBasis> > > pwd_vec = split_at_discontinuities(pwd2);

    double t0 = nearest_point(s, pwd_vec[0]);
    lpe->attach_end.param_set_value(t0);

    // 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 KnotHolderEntityAttachBegin::knot_get() const
{
    LPETaperStroke const * lpe = dynamic_cast<LPETaperStroke const*> (_effect);
    return lpe->start_attach_point;
}
Geom::Point KnotHolderEntityAttachEnd::knot_get() const
{
    LPETaperStroke const * lpe = dynamic_cast<LPETaperStroke const*> (_effect);
    return lpe->end_attach_point;
}
}


/* ######################## */

} //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 :