diff options
Diffstat (limited to 'src/snapper.h')
| -rw-r--r-- | src/snapper.h | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/src/snapper.h b/src/snapper.h new file mode 100644 index 0000000..18f324c --- /dev/null +++ b/src/snapper.h @@ -0,0 +1,166 @@ +// 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 <optional> +#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 SPObject; + +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<SPObject 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<SPObject 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 : |