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snapper.h

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#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, read the file 'COPYING' for more information.
 */

#include <map>
#include <list>
#include "libnr/nr-coord.h"
#include "libnr/nr-point.h"

#include "snapped-point.h"
#include "snapped-line.h"

struct SnappedConstraints {
    std::list<Inkscape::SnappedPoint> points; 
    std::list<Inkscape::SnappedLineSegment> lines;
    std::list<Inkscape::SnappedLine> grid_lines;
    std::list<Inkscape::SnappedLine> guide_lines;
};

struct SPNamedView;
struct SPItem;

namespace Inkscape
{

/// Parent for classes that can snap points to something
00037 class Snapper
{
public:
    Snapper() {}
    Snapper(SPNamedView const *nv, ::NR::Coord const d);
    virtual ~Snapper() {}

    /// Point types to snap.
00045     typedef int PointType;
    static const PointType SNAPPOINT_NODE;
    static const PointType SNAPPOINT_BBOX;
    static const PointType SNAPPOINT_GUIDE;

    void setSnapFrom(PointType t, bool s);
    bool getSnapFrom(PointType t) const;
    
    void setSnapperTolerance(NR::Coord t);    
    NR::Coord getSnapperTolerance() const; //returns the tolerance of the snapper in screen pixels (i.e. independent of zoom)
    bool getSnapperAlwaysSnap() const; //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.
    */
00060     virtual bool ThisSnapperMightSnap() const {return (_snap_enabled && _snap_from != 0);} // will likely be overridden by derived classes

    void setEnabled(bool s);
    bool getEnabled() const {return _snap_enabled;}

    void freeSnap(SnappedConstraints &sc,
                          PointType const &t,
                          NR::Point const &p,
                          bool const &first_point,                                             
                          std::vector<NR::Point> &points_to_snap,                         
                          SPItem const *it) const;

    void freeSnap(SnappedConstraints &sc,
                          PointType const &t,
                          NR::Point const &p,
                          bool const &first_point,                                             
                          std::vector<NR::Point> &points_to_snap,                         
                          std::list<SPItem const *> const &it) const;

    class ConstraintLine
    {
    public:
        ConstraintLine(NR::Point const &d) : _has_point(false), _direction(d) {}
        ConstraintLine(NR::Point const &p, NR::Point const &d) : _has_point(true), _point(p), _direction(d) {}

        bool hasPoint() const {
            return _has_point;
        }

        NR::Point getPoint() const {
            return _point;
        }

        NR::Point getDirection() const {
            return _direction;
        }
        
    private:

        bool _has_point;
        NR::Point _point;
        NR::Point _direction;
    };

    void constrainedSnap(SnappedConstraints &sc,
                                 PointType const &t,
                                 NR::Point const &p,
                                 bool const &first_point,
                                 std::vector<NR::Point> &points_to_snap,       
                                 ConstraintLine const &c,
                                 SPItem const *it) const;

    void constrainedSnap(SnappedConstraints &sc,
                                 PointType const &t,
                                 NR::Point const &p,
                                 bool const &first_point,
                                 std::vector<NR::Point> &points_to_snap,                         
                                 ConstraintLine const &c,
                                 std::list<SPItem const *> const &it) const;
                                 
protected:
    SPNamedView const *_named_view;
00122     int _snap_from; ///< bitmap of point types that we will snap from
00123     bool _snap_enabled; ///< true if this snapper is enabled, otherwise false
    
private:
00126     NR::Coord _snapper_tolerance;   ///< snap tolerance in desktop coordinates 
                                    // must be private to enforce the usage of getTolerance(), which retrieves 
                                    // the tolerance in screen pixels (making it zoom independent)


    /**
     *  Try to snap a point to whatever this snapper is interested in.  Any
     *  snap that occurs will be to the nearest "interesting" thing (e.g. a
     *  grid or guide line)
     *
     *  \param p Point to snap (desktop coordinates).
     *  \param it Items that should not be snapped to.
     *  \return Snapped point.
     */
    virtual void _doFreeSnap(SnappedConstraints &sc,
                                     PointType const &t,
                                     NR::Point const &p,
                                     bool const &first_point,                                             
                                     std::vector<NR::Point> &points_to_snap,
                                     std::list<SPItem const *> const &it) const = 0;

    /**
     *  Try to snap a point to whatever this snapper is interested in, where
     *  the snap point is constrained to lie along a specified vector from the
     *  original point.
     *
     *  \param p Point to snap (desktop coordinates).
     *  \param c Vector to constrain the snap to.
     *  \param it Items that should not be snapped to.
     *  \return Snapped point.
     */    
    virtual void _doConstrainedSnap(SnappedConstraints &sc,
                                            PointType const &t,
                                            NR::Point const &p,
                                            bool const &first_point,
                                            std::vector<NR::Point> &points_to_snap,
                                            ConstraintLine const &c,
                                            std::list<SPItem const *> const &it) const = 0;
};

}

#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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