src/live_effects/lpe-patternalongpath.cpp

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
 *
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */

#include <cmath>
#include <algorithm>
#include <vector>

#include <2geom/bezier-to-sbasis.h>

#include "live_effects/lpe-patternalongpath.h"
#include "live_effects/lpeobject.h"

#include "display/curve.h"

#include "object/sp-shape.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>


/* Theory in e-mail from J.F. Barraud
Let B be the skeleton path, and P the pattern (the path to be deformed).

P is a map t --> P(t) = ( x(t), y(t) ).
B is a map t --> B(t) = ( a(t), b(t) ).

The first step is to re-parametrize B by its arc length: this is the parametrization in which a point p on B is located by its distance s from start. One obtains a new map s --> U(s) = (a'(s),b'(s)), that still describes the same path B, but where the distance along B from start to
U(s) is s itself.

We also need a unit normal to the path. This can be obtained by computing a unit tangent vector, and rotate it by 90�. Call this normal vector N(s).

The basic deformation associated to B is then given by:

   (x,y) --> U(x)+y*N(x)

(i.e. we go for distance x along the path, and then for distance y along the normal)

Of course this formula needs some minor adaptations (as is it depends on the absolute position of P for instance, so a little translation is needed
first) but I think we can first forget about them.
*/

namespace Inkscape {
namespace LivePathEffect {

namespace WPAP {
    class KnotHolderEntityWidthPatternAlongPath : public LPEKnotHolderEntity {
    public:
        KnotHolderEntityWidthPatternAlongPath(LPEPatternAlongPath * effect) : LPEKnotHolderEntity(effect) {}
        ~KnotHolderEntityWidthPatternAlongPath() override
        {
            LPEPatternAlongPath *lpe = dynamic_cast<LPEPatternAlongPath *> (_effect);
            lpe->_knot_entity = nullptr;
        }
        void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
        Geom::Point knot_get() const override;
    };
} // WPAP

static const Util::EnumData<PAPCopyType> PAPCopyTypeData[PAPCT_END] = {
    // clang-format off
    {PAPCT_SINGLE,               N_("Single"),               "single"},
    {PAPCT_SINGLE_STRETCHED,     N_("Single, stretched"),    "single_stretched"},
    {PAPCT_REPEATED,             N_("Repeated"),             "repeated"},
    {PAPCT_REPEATED_STRETCHED,   N_("Repeated, stretched"),  "repeated_stretched"}
    // clang-format on
};
static const Util::EnumDataConverter<PAPCopyType> PAPCopyTypeConverter(PAPCopyTypeData, PAPCT_END);

LPEPatternAlongPath::LPEPatternAlongPath(LivePathEffectObject *lpeobject) :
    Effect(lpeobject),
    pattern(_("Pattern source:"), _("Path to put along the skeleton path"), "pattern", &wr, this, "M0,0 L1,0"),
    original_height(0.0),
    prop_scale(_("_Width:"), _("Width of the pattern"), "prop_scale", &wr, this, 1.0),
    copytype(_("Pattern copies:"), _("How many pattern copies to place along the skeleton path"),
        "copytype", PAPCopyTypeConverter, &wr, this, PAPCT_SINGLE_STRETCHED),
    scale_y_rel(_("Wid_th in units of length"),
        _("Scale the width of the pattern in units of its length"),
        "scale_y_rel", &wr, this, false),
    spacing(_("Spa_cing:"),
        // xgettext:no-c-format
        _("Space between copies of the pattern. Negative values allowed, but are limited to -90% of pattern width."),
        "spacing", &wr, this, 0),
    normal_offset(_("No_rmal offset:"), "", "normal_offset", &wr, this, 0),
    tang_offset(_("Tan_gential offset:"), "", "tang_offset", &wr, this, 0),
    prop_units(_("Offsets in _unit of pattern size"),
        _("Spacing, tangential and normal offset are expressed as a ratio of width/height"),
        "prop_units", &wr, this, false),
    vertical_pattern(_("Pattern is _vertical"), _("Rotate pattern 90 deg before applying"),
        "vertical_pattern", &wr, this, false),
    hide_knot(_("Hide width knot"), _("Hide width knot"),"hide_knot", &wr, this, false),
    fuse_tolerance(_("_Fuse nearby ends:"), _("Fuse ends closer than this number. 0 means don't fuse."),
        "fuse_tolerance", &wr, this, 0)
{
    registerParameter(&pattern);
    registerParameter(&copytype);
    registerParameter(&prop_scale);
    registerParameter(&scale_y_rel);
    registerParameter(&spacing);
    registerParameter(&normal_offset);
    registerParameter(&tang_offset);
    registerParameter(&prop_units);
    registerParameter(&vertical_pattern);
    registerParameter(&hide_knot);
    registerParameter(&fuse_tolerance);
    prop_scale.param_set_digits(3);
    prop_scale.param_set_increments(0.01, 0.10);
    _knot_entity = nullptr;
    _provides_knotholder_entities = true;

}

LPEPatternAlongPath::~LPEPatternAlongPath()
= default;

void LPEPatternAlongPath::transform_multiply(Geom::Affine const &postmul, bool /*set*/)
{
    if (sp_lpe_item && sp_lpe_item->pathEffectsEnabled() && sp_lpe_item->optimizeTransforms()) {
        pattern.param_transform_multiply(postmul, false);
    }
}

void
LPEPatternAlongPath::doBeforeEffect (SPLPEItem const* lpeitem)
{
    // get the pattern bounding box
    Geom::OptRect bbox = pattern.get_pathvector().boundsFast();
    if (bbox) {
        original_height = (*bbox)[Geom::Y].max() - (*bbox)[Geom::Y].min();
    }
    if (_knot_entity) {
        if (hide_knot) {
            helper_path.clear();
            _knot_entity->knot->hide();
        } else {
            _knot_entity->knot->show();
        }
        _knot_entity->update_knot();
    }
}

Geom::Piecewise<Geom::D2<Geom::SBasis> >
LPEPatternAlongPath::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
{
    using namespace Geom;

    // Don't allow empty path parameter:
    if ( pattern.get_pathvector().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;

    PAPCopyType type = copytype.get_value();

    D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(pattern.get_pwd2());
    Piecewise<SBasis> x0 = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]);
    Piecewise<SBasis> y0 = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : 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  = spacing;
        double noffset = normal_offset;
        double toffset = tang_offset;
        if (prop_units.get_value()){
            xspace  *= pattBndsX->extent();
            noffset *= pattBndsY->extent();
            toffset *= pattBndsX->extent();
        }

        //Prevent more than 90% overlap...
        if (xspace < -pattBndsX->extent() * 0.9) {
            xspace = -pattBndsX->extent() * 0.9;
        }
        //TODO: dynamical update of parameter ranges?
        //if (prop_units.get_value()){
        //        spacing.param_set_range(-.9, Geom::infinity());
        //    }else{
        //        spacing.param_set_range(-pattBndsX.extent()*.9, Geom::infinity());
        //    }

        y0 += noffset;

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

        for (auto path_i : paths_in){
            Piecewise<SBasis> x = x0;
            Piecewise<SBasis> y = y0;
            Piecewise<D2<SBasis> > uskeleton = arc_length_parametrization(path_i,2, 0.1);
            uskeleton = remove_short_cuts(uskeleton, 0.01);
            Piecewise<D2<SBasis> > n = rot90(derivative(uskeleton));
            if (Geom::are_near(pwd2_in[0].at0(),pwd2_in[pwd2_in.size()-1].at1(), 0.01)) {
                n = force_continuity(remove_short_cuts(n, 0.1), 0.01);
            } else {
                n = force_continuity(remove_short_cuts(n, 0.1));
            }
            int nbCopies = 0;
            double scaling = 1;
            switch(type) {
                case PAPCT_REPEATED:
                    nbCopies = static_cast<int>(floor((uskeleton.domain().extent() - toffset + xspace)/(pattBndsX->extent()+xspace)));
                    pattBndsX = Interval(pattBndsX->min(),pattBndsX->max()+xspace);
                    break;

                case PAPCT_SINGLE:
                    nbCopies = (toffset + pattBndsX->extent() < uskeleton.domain().extent()) ? 1 : 0;
                    break;

                case PAPCT_SINGLE_STRETCHED:
                    nbCopies = 1;
                    scaling = (uskeleton.domain().extent() - toffset)/pattBndsX->extent();
                    break;

                case PAPCT_REPEATED_STRETCHED:
                    // if uskeleton is closed:
                    if (are_near(path_i.segs.front().at0(), path_i.segs.back().at1())){
                        nbCopies = std::max(1, static_cast<int>(std::floor((uskeleton.domain().extent() - toffset)/(pattBndsX->extent()+xspace))));
                        pattBndsX = Interval(pattBndsX->min(),pattBndsX->max()+xspace);
                        scaling = (uskeleton.domain().extent() - toffset)/(((double)nbCopies)*pattBndsX->extent());
                        // if not closed: no space at the end
                    }else{
                        nbCopies = std::max(1, static_cast<int>(std::floor((uskeleton.domain().extent() - toffset + xspace)/(pattBndsX->extent()+xspace))));
                        pattBndsX = Interval(pattBndsX->min(),pattBndsX->max()+xspace);
                        scaling = (uskeleton.domain().extent() - toffset)/(((double)nbCopies)*pattBndsX->extent() - xspace);
                    }
                    break;

                default:
                    return pwd2_in;
            };

            //Ceil to 6 decimals
            scaling = ceil(scaling * 1000000) / 1000000;
            double pattWidth = pattBndsX->extent() * scaling;

            x *= scaling;
            if ( scale_y_rel.get_value() ) {
                y *= prop_scale * scaling;
            } else {
                y *= prop_scale;
            }
            x += toffset;

            double offs = 0;
            for (int i=0; i<nbCopies; i++){
                if (fuse_tolerance > 0){
                    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 (fuse_tolerance > 0){
            pre_output = fuse_nearby_ends(pre_output, fuse_tolerance);
            for (const auto & i : pre_output){
                output.concat(i);
            }
        }
        return output;
    } else {
        return pwd2_in;
    }
}

void
LPEPatternAlongPath::addCanvasIndicators(SPLPEItem const */*lpeitem*/, std::vector<Geom::PathVector> &hp_vec)
{
    hp_vec.push_back(helper_path);
}


void
LPEPatternAlongPath::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item)
{
    _knot_entity = new WPAP::KnotHolderEntityWidthPatternAlongPath(this);
    _knot_entity->create(nullptr, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:PatternAlongPath",
                         _("Change the width"));
    knotholder->add(_knot_entity);
    if (hide_knot) {
        _knot_entity->knot->hide();
        _knot_entity->update_knot();
    }
}

namespace WPAP {

void
KnotHolderEntityWidthPatternAlongPath::knot_set(Geom::Point const &p, Geom::Point const& /*origin*/, guint state)
{
    LPEPatternAlongPath *lpe = dynamic_cast<LPEPatternAlongPath *> (_effect);

    Geom::Point const s = snap_knot_position(p, state);
    SPShape const *sp_shape = dynamic_cast<SPShape const *>(SP_LPE_ITEM(item));
    if (sp_shape && lpe->original_height) {
        auto curve_before = SPCurve::copy(sp_shape->curveForEdit());
        if (curve_before) {
            Geom::Path const *path_in = curve_before->first_path();
            Geom::Point ptA = path_in->pointAt(Geom::PathTime(0, 0.0));
            Geom::Point B = path_in->pointAt(Geom::PathTime(1, 0.0));
            Geom::Curve const *first_curve = &path_in->curveAt(Geom::PathTime(0, 0.0));
            Geom::CubicBezier const *cubic = dynamic_cast<Geom::CubicBezier const *>(&*first_curve);
            Geom::Ray ray(ptA, B);
            if (cubic) {
                ray.setPoints(ptA, (*cubic)[1]);
            }
            ray.setAngle(ray.angle() + Geom::rad_from_deg(90));
            Geom::Point knot_pos = this->knot->pos * item->i2dt_affine().inverse();
            Geom::Coord nearest_to_ray = ray.nearestTime(knot_pos);
            if(nearest_to_ray == 0){
                lpe->prop_scale.param_set_value(-Geom::distance(s , ptA)/(lpe->original_height/2.0));
            } else {
                lpe->prop_scale.param_set_value(Geom::distance(s , ptA)/(lpe->original_height/2.0));
            }
        }
        if (!lpe->original_height) {
            lpe->prop_scale.param_set_value(0);
        }
        Inkscape::Preferences *prefs = Inkscape::Preferences::get();
        prefs->setDouble("/live_effects/skeletal/width", lpe->prop_scale);
    }
    sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), false, true);
}

Geom::Point
KnotHolderEntityWidthPatternAlongPath::knot_get() const
{
    LPEPatternAlongPath *lpe = dynamic_cast<LPEPatternAlongPath *> (_effect);
    SPShape const *sp_shape = dynamic_cast<SPShape const *>(SP_LPE_ITEM(item));
    if (sp_shape) {
        auto curve_before = SPCurve::copy(sp_shape->curveForEdit());
        if (curve_before) {
            Geom::Path const *path_in = curve_before->first_path();
            Geom::Point ptA = path_in->pointAt(Geom::PathTime(0, 0.0));
            Geom::Point B = path_in->pointAt(Geom::PathTime(1, 0.0));
            Geom::Curve const *first_curve = &path_in->curveAt(Geom::PathTime(0, 0.0));
            Geom::CubicBezier const *cubic = dynamic_cast<Geom::CubicBezier const *>(&*first_curve);
            Geom::Ray ray(ptA, B);
            if (cubic) {
                ray.setPoints(ptA, (*cubic)[1]);
            }
            ray.setAngle(ray.angle() + Geom::rad_from_deg(90));
            Geom::Point result_point = Geom::Point::polar(ray.angle(), (lpe->original_height/2.0) * lpe->prop_scale) + ptA;
            lpe->helper_path.clear();
            if (!lpe->hide_knot) {
                Geom::Path hp(result_point);
                hp.appendNew<Geom::LineSegment>(ptA);
                lpe->helper_path.push_back(hp);
                hp.clear();
            }
            return result_point;
        }
    }
    return Geom::Point();
}
} // namespace WPAP
} // 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 :