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// SPDX-License-Identifier: GPL-2.0-or-later
#ifndef SEEN_SNAPPER_H
#define SEEN_SNAPPER_H
/**
* \file src/snapper.h
* \brief Snapper class.
*
* Authors:
* Carl Hetherington <inkscape@carlh.net>
* Diederik van Lierop <mail@diedenrezi.nl>
*
* Released under GNU GPL v2+, read the file 'COPYING' for more information.
*/
#include <boost/optional.hpp>
#include <cstdio>
#include <list>
#include "snap-candidate.h"
#include "snapped-point.h"
#include "snapped-line.h"
#include "snapped-curve.h"
struct IntermSnapResults {
std::list<Inkscape::SnappedPoint> points;
std::list<Inkscape::SnappedLine> grid_lines;
std::list<Inkscape::SnappedLine> guide_lines;
std::list<Inkscape::SnappedCurve> curves;
};
class SnapManager;
class SPItem;
namespace Inkscape
{
/// Parent for classes that can snap points to something
class Snapper
{
public:
//Snapper() {} //does not seem to be used somewhere
Snapper(SnapManager *sm, ::Geom::Coord const t);
virtual ~Snapper() = default;
virtual Geom::Coord getSnapperTolerance() const = 0; //returns the tolerance of the snapper in screen pixels (i.e. independent of zoom)
virtual bool getSnapperAlwaysSnap() const = 0; //if true, then the snapper will always snap, regardless of its tolerance
/**
* \return true if this Snapper will snap at least one kind of point.
*/
virtual bool ThisSnapperMightSnap() const {return _snap_enabled;} // will likely be overridden by derived classes
// These four methods are only used for grids, for which snapping can be enabled individually
void setEnabled(bool s);
void setSnapVisibleOnly(bool s);
bool getEnabled() const {return _snap_enabled;}
bool getSnapVisibleOnly() const {return _snap_visible_only;}
virtual void freeSnap(IntermSnapResults &/*isr*/,
Inkscape::SnapCandidatePoint const &/*p*/,
Geom::OptRect const &/*bbox_to_snap*/,
std::vector<SPItem const *> const */*it*/,
std::vector<SnapCandidatePoint> */*unselected_nodes*/) const {};
// Class for storing the constraint for constrained snapping; can be
// - a line (infinite line with origin, running through _point pointing in _direction)
// - a direction (infinite line without origin, i.e. only a direction vector, stored in _direction)
// - a circle (_point denotes the center, _radius doesn't need an explanation, _direction contains
// the vector from the origin to the original untransformed point);
class SnapConstraint
{
private:
enum SnapConstraintType {LINE, DIRECTION, CIRCLE, UNDEFINED};
public:
// Constructs a direction constraint, e.g. horizontal or vertical but without a specified point
SnapConstraint(Geom::Point const &d) : _point(), _direction(d), _radius(0), _type(DIRECTION) {}
// Constructs a linear constraint
SnapConstraint(Geom::Point const &p, Geom::Point const &d) : _point(p), _direction(d), _radius(0), _type(LINE) {}
// Orthogonal version
SnapConstraint(Geom::Point const &p, Geom::Dim2 const &d) : _point(p), _direction(), _radius(0), _type(LINE) {_direction[d] = 1.;}
SnapConstraint(Geom::Line const &l) : _point(l.origin()), _direction(l.versor()), _radius(0), _type(LINE) {}
// Constructs a circular constraint
SnapConstraint(Geom::Point const &p, Geom::Point const &d, Geom::Coord const &r) : _point(p), _direction(d), _radius(r), _type(CIRCLE) {}
// Undefined, or empty constraint
SnapConstraint() : _point(), _direction(), _radius(0), _type(UNDEFINED) {}
bool hasPoint() const {return _type != DIRECTION && _type != UNDEFINED;}
Geom::Point getPoint() const {
assert(_type != DIRECTION && _type != UNDEFINED);
return _point;
}
Geom::Point getDirection() const {
return _direction;
}
Geom::Coord getRadius() const {
assert(_type == CIRCLE);
return _radius;
}
bool isCircular() const { return _type == CIRCLE; }
bool isLinear() const { return _type == LINE; }
bool isDirection() const { return _type == DIRECTION; }
bool isUndefined() const { return _type == UNDEFINED; }
Geom::Point projection(Geom::Point const &p) const { // returns the projection of p on this constraint
if (_type == CIRCLE) {
// project on to a circular constraint
Geom::Point v_orig = p - _point;
Geom::Coord l = Geom::L2(v_orig);
if (l > 0) {
return _point + _radius * v_orig/l; // Length of _direction is equal to the radius
} else {
// point to be projected is exactly at the center of the circle, so any point on the circle is a projection
return _point + Geom::Point(_radius, 0);
}
} else if (_type != UNDEFINED){
// project on to a linear constraint
Geom::Point const p1_on_cl = (_type == LINE) ? _point : p;
Geom::Point const p2_on_cl = p1_on_cl + _direction;
return Geom::projection(p, Geom::Line(p1_on_cl, p2_on_cl));
} else {
printf("WARNING: Bug: trying to find the projection onto an undefined constraint");
return Geom::Point();
}
}
private:
Geom::Point _point;
Geom::Point _direction;
Geom::Coord _radius;
SnapConstraintType _type;
};
virtual void constrainedSnap(IntermSnapResults &/*isr*/,
Inkscape::SnapCandidatePoint const &/*p*/,
Geom::OptRect const &/*bbox_to_snap*/,
SnapConstraint const &/*c*/,
std::vector<SPItem const *> const */*it*/,
std::vector<SnapCandidatePoint> */*unselected_nodes*/) const {};
protected:
SnapManager *_snapmanager;
// This is only used for grids, for which snapping can be enabled individually
bool _snap_enabled; ///< true if this snapper is enabled, otherwise false
bool _snap_visible_only;
};
}
#endif /* !SEEN_SNAPPER_H */
/*
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 :
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