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snapped-point.cpp

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/**
 *  \file src/snapped-point.cpp
 *  \brief SnappedPoint class.
 *
 *  Authors:
 *    Mathieu Dimanche <mdimanche@free.fr>
 *    Diederik van Lierop <mail@diedenrezi.nl>
 *
 *  Released under GNU GPL, read the file 'COPYING' for more information.
 */

#include <gtk/gtk.h>
#include "snapped-point.h"
#include "preferences.h"

// overloaded constructor
Inkscape::SnappedPoint::SnappedPoint(Geom::Point const &p, SnapSourceType const &source, SnapTargetType const &target, Geom::Coord const &d, Geom::Coord const &t, bool const &a, bool const &fully_constrained)
    : _point(p), _source(source), _target(target), _distance(d), _tolerance(std::max(t,1.0)), _always_snap(a)
{
    // tolerance should never be smaller than 1 px, as it is used for normalization in isOtherSnapBetter. We don't want a division by zero.
    _at_intersection = false;
    _fully_constrained = fully_constrained;
    _second_distance = NR_HUGE;
    _second_tolerance = 1;
    _second_always_snap = false;
    _transformation = Geom::Point(1,1);
    _pointer_distance = NR_HUGE;
}

Inkscape::SnappedPoint::SnappedPoint(Geom::Point const &p, SnapSourceType const &source, SnapTargetType const &target, Geom::Coord const &d, Geom::Coord const &t, bool const &a, bool const &at_intersection, bool const &fully_constrained, Geom::Coord const &d2, Geom::Coord const &t2, bool const &a2)
    : _point(p), _source(source), _target(target), _at_intersection(at_intersection), _fully_constrained(fully_constrained), _distance(d), _tolerance(std::max(t,1.0)), _always_snap(a),
    _second_distance(d2), _second_tolerance(std::max(t2,1.0)), _second_always_snap(a2)
{
    // tolerance should never be smaller than 1 px, as it is used for normalization in
    // isOtherSnapBetter. We don't want a division by zero.
    _transformation = Geom::Point(1,1);
    _pointer_distance = NR_HUGE;
}

Inkscape::SnappedPoint::SnappedPoint()
{
    _point = Geom::Point(0,0);
    _source = SNAPSOURCE_UNDEFINED,
    _target = SNAPTARGET_UNDEFINED,
    _at_intersection = false;
    _fully_constrained = false;
    _distance = NR_HUGE;
    _tolerance = 1;
    _always_snap = false;
    _second_distance = NR_HUGE;
    _second_tolerance = 1;
    _second_always_snap = false;
    _transformation = Geom::Point(1,1);
    _pointer_distance = NR_HUGE;
}

Inkscape::SnappedPoint::~SnappedPoint()
{
}

void Inkscape::SnappedPoint::getPoint(Geom::Point &p) const
{
    // When we have snapped
    if (getSnapped()) {
        // then return the snapped point by overwriting p
        p = _point;
    } //otherwise p will be left untouched; this way the caller doesn't have to check wether we've snapped
}

// search for the closest snapped point
bool getClosestSP(std::list<Inkscape::SnappedPoint> &list, Inkscape::SnappedPoint &result)
{
    bool success = false;

    for (std::list<Inkscape::SnappedPoint>::const_iterator i = list.begin(); i != list.end(); i++) {
      if ((i == list.begin()) || (*i).getSnapDistance() < result.getSnapDistance()) {
            result = *i;
            success = true;
        }
    }

    return success;
}

bool Inkscape::SnappedPoint::isOtherSnapBetter(Inkscape::SnappedPoint const &other_one, bool weighted) const
{

    double dist_other = other_one.getSnapDistance();
    double dist_this = getSnapDistance();

    // The distance to the pointer should only be taken into account when finding the best snapped source node (when
    // there's more than one). It is not useful when trying to find the best snapped target point.
    // (both the snap distance and the pointer distance are measured in document pixels, not in screen pixels)
    if (weighted) {

      Geom::Coord const dist_pointer_other = other_one.getPointerDistance();
      Geom::Coord const dist_pointer_this = getPointerDistance();
      // Weight factor: controls which node should be preferred for snapping, which is either
        // the node with the closest snap (w = 0), or the node closest to the mousepointer (w = 1)
        Inkscape::Preferences *prefs = Inkscape::Preferences::get();
        double w = prefs->getDoubleLimited("/options/snapweight/value", 0.5, 0, 1);
        if (prefs->getBool("/options/snapclosestonly/value", false)) {
            w = 1;
        }
        if (w > 0) {
            if (!(w == 1 && dist_pointer_this == dist_pointer_other)) {
                  // When accounting for the distance to the mouse pointer, then at least one of the snapped points should
                        // have that distance set. If not, then this is a bug. Either "weighted" must be set to false, or the
                        // mouse pointer distance must be set.
                        g_assert(dist_pointer_this != NR_HUGE || dist_pointer_other != NR_HUGE);
                        // The snap distance will always be smaller than the tolerance set for the snapper. The pointer distance can
                        // however be very large. To compare these in a fair way, we will have to normalize these metrics first
                        // The closest pointer distance will be normalized to 1.0; the other one will be > 1.0
                        // The snap distance will be normalized to 1.0 if it's equal to the snapper tolerance
                        double const norm_p = std::min(dist_pointer_this, dist_pointer_other);
                        double const norm_t_other = std::min(50.0, other_one.getTolerance());
                        double const norm_t_this = std::min(50.0, getTolerance());
                        dist_other = w * dist_pointer_other / norm_p + (1-w) * dist_other / norm_t_other;
                        dist_this = w * dist_pointer_this / norm_p + (1-w) * dist_this / norm_t_this;
            }
        }
    }

    // If it's closer
    bool c1 = dist_other < dist_this;
    // or, if it's for a snapper with "always snap" turned on, and the previous wasn't
    bool c2 = other_one.getAlwaysSnap() && !getAlwaysSnap();
    // But in no case fall back from a snapper with "always snap" on to one with "always snap" off
    bool c2n = !other_one.getAlwaysSnap() && getAlwaysSnap();
    // or, if we have a fully constrained snappoint (e.g. to a node or an intersection), while the previous one was only partly constrained (e.g. to a line)
    bool c3 = other_one.getFullyConstrained() && !getFullyConstrained();
    // But in no case fall back; (has less priority than c3n, so it is allowed to fall back when c3 is true, see below)
    bool c3n = !other_one.getFullyConstrained() && getFullyConstrained();

    // When both are fully constrained AND coincident, then prefer nodes over intersections
    bool d = other_one.getFullyConstrained() && getFullyConstrained() && (Geom::L2(other_one.getPoint() - getPoint()) < 1e-9);
    bool c4 = d && !other_one.getAtIntersection() && getAtIntersection();
    // But don't fall back...
    bool c4n = d && other_one.getAtIntersection() && !getAtIntersection();

    // or, if it's just as close then consider the second distance
    bool c5a = (dist_other == dist_this);
    bool c5b = other_one.getSecondSnapDistance() < getSecondSnapDistance();

    // std::cout << other_one.getPoint() << " (Other one, dist = " << dist_other << ") vs. " << getPoint() << " (this one, dist = " << dist_this << ") ---> ";
    // std::cout << "c1 = " << c1 << " | c2 = " << c2 << " | c2n = " << c2n << " | c3 = " << c3 << " | c3n = " << c3n << " | c4 = " << c4 << " | c4n = " << c4n << " | c5a = " << c5a << " | c5b = " << c5b << std::endl;
    return (c1 || c2 || c3 || c4 || (c5a && c5b)) && !c2n && (!c3n || c2) && !c4n;
}

/*
  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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