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/**
* \file line-snapper.cpp
* \brief LineSnapper class.
*
* Authors:
* Diederik van Lierop <mail@diedenrezi.nl>
* And others...
*
* Copyright (C) 1999-2007 Authors
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
#include "libnr/nr-values.h"
#include "libnr/nr-point-fns.h"
#include <2geom/geom.h>
#include "line-snapper.h"
#include "snapped-line.cpp"
#include <gtk/gtk.h>
Inkscape::LineSnapper::LineSnapper(SPNamedView const *nv, NR::Coord const d) : Snapper(nv, d)
{
}
void Inkscape::LineSnapper::_doFreeSnap(SnappedConstraints &sc,
Inkscape::Snapper::PointType const &t,
NR::Point const &p,
bool const &f,
std::vector<NR::Point> &points_to_snap,
std::list<SPItem const *> const &it) const
{
Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);
/* Get the lines that we will try to snap to */
const LineList lines = _getSnapLines(p);
// std::cout << "snap point " << p << " to: " << std::endl;
for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
NR::Point const p1 = i->second; // point at guide/grid line
NR::Point const p2 = p1 + NR::rot90(i->first); // 2nd point at guide/grid line
// std::cout << " line through " << i->second << " with normal " << i->first;
g_assert(i->first != NR::Point(0,0)); // otherwise we'll have div. by zero because NR::L2(d2) = 0
// p_proj = projection of p on the grid/guide line running from p1 to p2
// p_proj = p1 + u (p2 - p1)
// calculate u according to "Minimum Distance between a Point and a Line"
// see http://local.wasp.uwa.edu.au/~pbourke/geometry/pointline/
NR::Point const d1(p-p1); // delta 1
NR::Point const d2(p2-p1); // delta 1
double const u = (d1[NR::X] * d2[NR::X] + d1[NR::Y] * d2[NR::Y]) / (NR::L2(d2) * NR::L2(d2));
NR::Point const p_proj(p1 + u*(p2-p1));
NR::Coord const dist = NR::L2(p_proj - p);
//Store any line that's within snapping range
if (dist < getDistance()) {
_addSnappedLine(sc, p_proj, dist, i->first, i->second);
// std::cout << " -> distance = " << dist;
}
// std::cout << std::endl;
}
}
void Inkscape::LineSnapper::_doConstrainedSnap(SnappedConstraints &sc,
Inkscape::Snapper::PointType const &/*t*/,
NR::Point const &p,
bool const &/*f*/,
std::vector<NR::Point> &/*points_to_snap*/,
ConstraintLine const &c,
std::list<SPItem const *> const &/*it*/) const
{
Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);
/* Get the lines that we will try to snap to */
const LineList lines = _getSnapLines(p);
for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
/* Normal to the line we're trying to snap along */
NR::Point const n(NR::rot90(NR::unit_vector(c.getDirection())));
NR::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;
/* Constant term of the line we're trying to snap along */
NR::Coord const q0 = dot(n, point_on_line);
/* Constant term of the grid or guide line */
NR::Coord const q1 = dot(i->first, i->second);
/* Try to intersect this line with the target line */
Geom::Point t_2geom(NR_HUGE, NR_HUGE);
Geom::IntersectorKind const k = Geom::line_intersection(n.to_2geom(), q0, i->first.to_2geom(), q1, t_2geom);
NR::Point t(t_2geom);
if (k == Geom::intersects) {
const NR::Coord dist = L2(t - p);
//Store any line that's within snapping range
if (dist < getDistance()) {
_addSnappedLine(sc, t, dist, c.getDirection(), t);
}
}
}
}
/*
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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