src/live_effects/lpe-bendpath.cpp

	lpe-bendpath.cpp revision 4b5cd12effd117d25afc7c11ce4ae0387a7f76c7
/*
 * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
 * Copyright (C) Steren Giannini 2008 <steren.giannini@gmail.com>
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include "live_effects/lpe-bendpath.h"
#include "sp-shape.h"
#include "sp-item.h"
#include "sp-path.h"
#include "sp-item-group.h"
#include "svg/svg.h"
#include "ui/widget/scalar.h"

#include <2geom/sbasis.h>
#include <2geom/sbasis-geometric.h>
#include <2geom/bezier-to-sbasis.h>
#include <2geom/sbasis-to-bezier.h>
#include <2geom/d2.h>
#include <2geom/piecewise.h>

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

#include <glibmm/i18n.h>

#include <algorithm>

using std::vector;


/* 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 {

Geom::PathVector bp_helper_path;
namespace BeP {
class KnotHolderEntityWidthBendPath : public LPEKnotHolderEntity {
    public:
        KnotHolderEntityWidthBendPath(LPEBendPath * effect) : LPEKnotHolderEntity(effect) {}
        virtual void knot_set(Geom::Point const &p, Geom::Point const &origin, guint state);
        virtual Geom::Point knot_get() const;
    };
} // BeP

LPEBendPath::LPEBendPath(LivePathEffectObject *lpeobject) :
    Effect(lpeobject),
    bend_path(_("Bend path:"), _("Path along which to bend the original path"), "bendpath", &wr, this, "M0,0 L1,0"),
    original_height(0.0),
    prop_scale(_("_Width:"), _("Width of the path"), "prop_scale", &wr, this, 1.0),
    scale_y_rel(_("W_idth in units of length"), _("Scale the width of the path in units of its length"), "scale_y_rel", &wr, this, false),
    vertical_pattern(_("_Original path is vertical"), _("Rotates the original 90 degrees, before bending it along the bend path"), "vertical", &wr, this, false)
{
    registerParameter( dynamic_cast<Parameter *>(&bend_path) );
    registerParameter( dynamic_cast<Parameter *>(&prop_scale) );
    registerParameter( dynamic_cast<Parameter *>(&scale_y_rel) );
    registerParameter( dynamic_cast<Parameter *>(&vertical_pattern) );

    prop_scale.param_set_digits(3);
    prop_scale.param_set_increments(0.01, 0.10);

    _provides_knotholder_entities = true;
    concatenate_before_pwd2 = true;
}

LPEBendPath::~LPEBendPath()
{

}

void
LPEBendPath::doBeforeEffect (SPLPEItem const* lpeitem)
{
    // get the item bounding box
    original_bbox(lpeitem);
    original_height = boundingbox_Y.max() - boundingbox_Y.min();
    SPLPEItem * item = const_cast<SPLPEItem*>(lpeitem);

    item->apply_to_clippath(item);
    item->apply_to_mask(item);
}

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

/* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */

    if (bend_path.changed) {
        uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(bend_path.get_pwd2()),2,.1);
        uskeleton = remove_short_cuts(uskeleton,.01);
        n = rot90(derivative(uskeleton));
        n = force_continuity(remove_short_cuts(n,.1));

        bend_path.changed = false;
    }

    if (uskeleton.empty()) {
        return pwd2_in;  /// \todo or throw an exception instead? might be better to throw an exception so that the UI can display an error message or smth
    }

    D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(pwd2_in);
    Piecewise<SBasis> x = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]);
    Piecewise<SBasis> y = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : Piecewise<SBasis>(patternd2[1]);

    Interval bboxHorizontal = vertical_pattern.get_value() ? boundingbox_Y : boundingbox_X;
    Interval bboxVertical = vertical_pattern.get_value() ? boundingbox_X : boundingbox_Y;

    //We use the group bounding box size or the path bbox size to translate well x and y
    x-= bboxHorizontal.min();
    y-= bboxVertical.middle();

    double scaling = uskeleton.cuts.back()/bboxHorizontal.extent();

    if (scaling != 1.0) {
        x*=scaling;
    }

    if ( scale_y_rel.get_value() ) {
        y*=(scaling*prop_scale);
    } else {
        if (prop_scale != 1.0) y *= prop_scale;
    }

    Piecewise<D2<SBasis> > output = compose(uskeleton,x) + y*compose(n,x);
    return output;
}

void
LPEBendPath::resetDefaults(SPItem const* item)
{
    Effect::resetDefaults(item);

    original_bbox(SP_LPE_ITEM(item));

    Geom::Point start(boundingbox_X.min(), (boundingbox_Y.max()+boundingbox_Y.min())/2);
    Geom::Point end(boundingbox_X.max(), (boundingbox_Y.max()+boundingbox_Y.min())/2);

    if ( Geom::are_near(start,end) ) {
        end += Geom::Point(1.,0.);
    }

    Geom::Path path;
    path.start( start );
    path.appendNew<Geom::LineSegment>( end );
    bend_path.set_new_value( path.toPwSb(), true );
}

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

void
LPEBendPath::addKnotHolderEntities(KnotHolder *knotholder, SPDesktop *desktop, SPItem *item)
{
    KnotHolderEntity *e = new BeP::KnotHolderEntityWidthBendPath(this);
    e->create(desktop, item, knotholder, Inkscape::CTRL_TYPE_UNKNOWN, _("Change the width"), SP_KNOT_SHAPE_CIRCLE);
    knotholder->add(e);
}

namespace BeP {

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

    Geom::Point const s = snap_knot_position(p, state);
    Geom::Path path_in = lpe->bend_path.get_pathvector().pathAt(Geom::PathVectorTime(0, 0, 0.0));
    Geom::Point ptA = path_in.pointAt(Geom::PathTime(0, 0.0));
    lpe->prop_scale.param_set_value(Geom::distance(s , ptA)/(lpe->original_height/2.0));

    sp_lpe_item_update_patheffect (SP_LPE_ITEM(item), false, true);
}

Geom::Point
KnotHolderEntityWidthBendPath::knot_get() const
{
    LPEBendPath *lpe = dynamic_cast<LPEBendPath *> (_effect);

    Geom::Path path_in = lpe->bend_path.get_pathvector().pathAt(Geom::PathVectorTime(0, 0, 0.0));
    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]);
    }
    Geom::Angle first_curve_angle = ray.transformed(Geom::Rotate(Geom::deg_to_rad(90))).angle();
    Geom::Point result_point = Geom::Point::polar(first_curve_angle, (lpe->original_height * lpe->prop_scale)/2.0) + ptA;

    bp_helper_path.clear();
    Geom::Path hp(result_point);
    hp.appendNew<Geom::LineSegment>(ptA);
    bp_helper_path.push_back(hp);
    hp.clear();

    return result_point;
}
} // namespace BeP
} // 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 :