inkscape/src/snapped-line.cpp

	snapped-line.cpp revision c3bc76d351bed6e320f6dbf2242012f026659287
/**
 *    \file src/snapped-line.cpp
 *    \brief SnappedLine class.
 *
 *    Authors:
 *      Diederik van Lierop <mail@diedenrezi.nl>
 *
 *    Released under GNU GPL, read the file 'COPYING' for more information.
 */

#include "snapped-line.h"
#include <2geom/geom.h>
#include "libnr/nr-values.h"

Inkscape::SnappedLineSegment::SnappedLineSegment(NR::Point snapped_point, NR::Coord snapped_distance, NR::Point start_point_of_line, NR::Point end_point_of_line)
    : _start_point_of_line(start_point_of_line), _end_point_of_line(end_point_of_line)
{
    _distance = snapped_distance;
    _point = snapped_point;
    _at_intersection = false;
}

Inkscape::SnappedLineSegment::SnappedLineSegment()
{
    _start_point_of_line = NR::Point(0,0);
    _end_point_of_line = NR::Point(0,0);
    _distance = NR_HUGE;
    _point = NR::Point(0,0);
    _at_intersection = false;
}


Inkscape::SnappedLineSegment::~SnappedLineSegment()
{
}

Inkscape::SnappedPoint Inkscape::SnappedLineSegment::intersect(SnappedLineSegment const &line) const
{
    //TODO: Diederik, implement the intersection
    NR::Point const intersection = NR::Point(NR_HUGE, NR_HUGE);

    //if (result == INTERSECTS) {
        /* The relevant snapped distance is the distance to the closest snapped line, not the
        distance to the intersection. For example, when a box is almost aligned with a grid
        in both horizontal and vertical directions, the distance to the intersection of the
        grid lines will always be larger then the distance to a grid line. We will be snapping
        to the closest snapped point however, so if we ever want to snap to the intersection
        then the distance to it should at least be equal to the other distance, not greater
        than it, as that would rule the intersection out
        */
    NR::Coord distance = std::min(_distance, line.getDistance());
    //}
    return SnappedPoint(intersection, distance);
};


Inkscape::SnappedLine::SnappedLine(NR::Point snapped_point, NR::Coord snapped_distance, NR::Point normal_to_line, NR::Point point_on_line)
    : _normal_to_line(normal_to_line), _point_on_line(point_on_line)
{
    _distance = snapped_distance;
    _point = snapped_point;
    _at_intersection = false;
}

Inkscape::SnappedLine::SnappedLine()
{
    _normal_to_line = NR::Point(0,0);
    _point_on_line = NR::Point(0,0);
    _distance = NR_HUGE;
    _point = NR::Point(0,0);
    _at_intersection = false;
}

Inkscape::SnappedLine::~SnappedLine()
{
}

Inkscape::SnappedPoint Inkscape::SnappedLine::intersect(SnappedLine const &line) const
{
    // Calculate the intersection of to lines, which are both within snapping range
    // The point of intersection should be considered for snapping, but might be outside the snapping range

    Geom::Point intersection_2geom(NR_HUGE, NR_HUGE);
    NR::Coord distance = NR_HUGE;

    Geom::IntersectorKind result = Geom::line_intersection(getNormal().to_2geom(), getConstTerm(),
                                   line.getNormal().to_2geom(), line.getConstTerm(), intersection_2geom);
    NR::Point intersection(intersection_2geom);

    if (result == Geom::intersects) {
        /* The relevant snapped distance is the distance to the closest snapped line, not the
        distance to the intersection. For example, when a box is almost aligned with a grid
        in both horizontal and vertical directions, the distance to the intersection of the
        grid lines will always be larger then the distance to a grid line. We will be snapping
        to the closest snapped point however, so if we ever want to snap to the intersection
        then the distance to it should at least be equal to the other distance, not greater
        than it, as that would rule the intersection out
        */
        distance = std::min(_distance, line.getDistance());
        //std::cout << "Intersected nicely, now getSIL distance = " << distance << std::endl;
    }

    return SnappedPoint(intersection, distance, result == Geom::intersects);
}

// search for the closest snapped line
bool getClosestSL(std::list<Inkscape::SnappedLine> &list, Inkscape::SnappedLine &result)
{
    bool success = false;

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

    return success;
}

// search for the closest intersection of two snapped lines, which are both member of the same collection
bool getClosestIntersectionSL(std::list<Inkscape::SnappedLine> &list, Inkscape::SnappedPoint &result)
{
    bool success = false;

    for (std::list<Inkscape::SnappedLine>::const_iterator i = list.begin(); i != list.end(); i++) {
        std::list<Inkscape::SnappedLine>::const_iterator j = i;
        j++;
        for (; j != list.end(); j++) {
            Inkscape::SnappedPoint sp = (*i).intersect(*j);
            if (sp.getAtIntersection()) {
                if (!success || sp.getDistance() < result.getDistance()) {
                    // !success because the first intersection cannot be compared to a previous one
                    result = sp;
                    success = true;
                }
            }
        }
    }

    return success;
}

// search for the closest intersection of two snapped lines, which are in two different collections
bool getClosestIntersectionSL(std::list<Inkscape::SnappedLine> &list1, std::list<Inkscape::SnappedLine> &list2, Inkscape::SnappedPoint &result)
{
    bool success = false;

    for (std::list<Inkscape::SnappedLine>::const_iterator i = list1.begin(); i != list1.end(); i++) {
        for (std::list<Inkscape::SnappedLine>::const_iterator j = list2.begin(); j != list2.end(); j++) {
            Inkscape::SnappedPoint sp = (*i).intersect(*j);
            if (sp.getAtIntersection()) {
                if (!success || sp.getDistance() < result.getDistance()) {
                    // !success because the first intersection cannot be compared to a previous one
                    result = sp;
                    success = true;
                }
            }
        }
    }

    return success;
}

/*
  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 :