lpe-tangent_to_curve.cpp

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Authors:
 *   Johan Engelen
 *   Maximilian Albert
 *
 * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
 * Copyright (C) Maximilian Albert 2008 <maximilian.albert@gmail.com>
 *
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */
 
#include "lpe-tangent_to_curve.h"
 
#include "display/curve.h"
 
#include "object/sp-shape.h"
#include "object/sp-object-group.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 {
 
namespace TtC {
 
class KnotHolderEntityAttachPt : public LPEKnotHolderEntity {
public:
    KnotHolderEntityAttachPt(LPETangentToCurve *effect) : LPEKnotHolderEntity(effect) {};
    void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
    Geom::Point knot_get() const override;
};
 
class KnotHolderEntityLeftEnd : public LPEKnotHolderEntity {
public:
    KnotHolderEntityLeftEnd(LPETangentToCurve *effect) : LPEKnotHolderEntity(effect) {};
    void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
    Geom::Point knot_get() const override;
};
 
class KnotHolderEntityRightEnd : public LPEKnotHolderEntity
{
public:
    KnotHolderEntityRightEnd(LPETangentToCurve *effect) : LPEKnotHolderEntity(effect) {};
    void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state) override;
    Geom::Point knot_get() const override;
};
 
} // namespace TtC
 
LPETangentToCurve::LPETangentToCurve(LivePathEffectObject *lpeobject) :
    Effect(lpeobject),
    angle(_("Angle:"), _("Additional angle between tangent and curve"), "angle", &wr, this, 0.0),
    t_attach(_("Location along curve:"), _("Location of the point of attachment along the curve (between 0.0 and number-of-segments)"), "t_attach", &wr, this, 0.5),
    length_left(_("Length left:"), _("Specifies the left end of the tangent"), "length-left", &wr, this, 150),
    length_right(_("Length right:"), _("Specifies the right end of the tangent"), "length-right", &wr, this, 150)
{
    show_orig_path = true;
    _provides_knotholder_entities = true;
 
    registerParameter(&angle);
    registerParameter(&t_attach);
    registerParameter(&length_left);
    registerParameter(&length_right);
}
 
LPETangentToCurve::~LPETangentToCurve() = default;
 
Geom::Piecewise<Geom::D2<Geom::SBasis> >
LPETangentToCurve::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
{
    using namespace Geom;
    Piecewise<D2<SBasis> > output;
 
    ptA = pwd2_in.valueAt(t_attach);
    derivA = unit_vector(derivative(pwd2_in).valueAt(t_attach));
 
    // TODO: Why are positive angles measured clockwise, not counterclockwise?
    Geom::Rotate rot(Geom::Rotate::from_degrees(-angle));
    derivA = derivA * rot;
 
    C = ptA - derivA * length_left;
    D = ptA + derivA * length_right;
 
    output = Piecewise<D2<SBasis> >(D2<SBasis>(SBasis(C[X], D[X]), SBasis(C[Y], D[Y])));
 
    return output;
}
 
void
LPETangentToCurve::addKnotHolderEntities(KnotHolder *knotholder, SPItem *item) {
    {
        KnotHolderEntity *e = new TtC::KnotHolderEntityAttachPt(this);
        e->create(nullptr, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:TangentToCurvePT",
                  _("Adjust the point of attachment of the tangent"));
        knotholder->add(e);
    }
    {
        KnotHolderEntity *e = new TtC::KnotHolderEntityLeftEnd(this);
        e->create(nullptr, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:TangentToCurveLeftEnd",
                  _("Adjust the <b>left</b> end of the tangent"));
        knotholder->add(e);
    }
    {
        KnotHolderEntity *e = new TtC::KnotHolderEntityRightEnd(this);
        e->create(nullptr, item, knotholder, Inkscape::CANVAS_ITEM_CTRL_TYPE_LPE, "LPE:TangetToCurveRightEnd",
                  _("Adjust the <b>right</b> end of the tangent"));
        knotholder->add(e);
    }
};
 
namespace TtC {
 
void
KnotHolderEntityAttachPt::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint state)
{
    using namespace Geom;
 
    LPETangentToCurve* lpe = dynamic_cast<LPETangentToCurve *>(_effect);
 
    Geom::Point const s = snap_knot_position(p, state);
 
    if ( !is<SPShape>(lpe->sp_lpe_item) ) {
        //lpe->t_attach.param_set_value(0);
        g_warning("LPEItem is not a path! %s:%d\n", __FILE__, __LINE__);
        return;
    }
    Piecewise<D2<SBasis> > pwd2 = paths_to_pw( lpe->pathvector_before_effect );
    
    double t0 = nearest_time(s, pwd2);
    lpe->t_attach.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 (cast<SPLPEItem>(item), false, true);
}
 
void
KnotHolderEntityLeftEnd::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint state)
{
    LPETangentToCurve *lpe = dynamic_cast<LPETangentToCurve *>(_effect);
 
    Geom::Point const s = snap_knot_position(p, state);
 
    double lambda = Geom::nearest_time(s, lpe->ptA, lpe->derivA);
    lpe->length_left.param_set_value(-lambda);
 
    sp_lpe_item_update_patheffect (cast<SPLPEItem>(item), false, true);
}
 
void
KnotHolderEntityRightEnd::knot_set(Geom::Point const &p, Geom::Point const &/*origin*/, guint state)
{
    LPETangentToCurve *lpe = dynamic_cast<LPETangentToCurve *>(_effect);
    
    Geom::Point const s = snap_knot_position(p, state);
 
    double lambda = Geom::nearest_time(s, lpe->ptA, lpe->derivA);
    lpe->length_right.param_set_value(lambda);
 
    sp_lpe_item_update_patheffect (cast<SPLPEItem>(item), false, true);
}
 
Geom::Point
KnotHolderEntityAttachPt::knot_get() const
{
    LPETangentToCurve const *lpe = dynamic_cast<LPETangentToCurve const*>(_effect);
    return lpe->ptA;
}
 
Geom::Point
KnotHolderEntityLeftEnd::knot_get() const
{
    LPETangentToCurve const *lpe = dynamic_cast<LPETangentToCurve const*>(_effect);
    return lpe->C;
}
 
Geom::Point
KnotHolderEntityRightEnd::knot_get() const
{
    LPETangentToCurve const *lpe = dynamic_cast<LPETangentToCurve const*>(_effect);
    return lpe->D;
}
 
} // namespace TtC
 
} //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:
*/
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