1 /**
2 * \file line-snapper.cpp
3 * \brief LineSnapper class.
4 *
5 * Authors:
6 * Diederik van Lierop <mail@diedenrezi.nl>
7 * And others...
8 *
9 * Copyright (C) 1999-2007 Authors
10 *
11 * Released under GNU GPL, read the file 'COPYING' for more information
12 */
14 #include "libnr/nr-values.h"
15 #include "libnr/nr-point-fns.h"
16 #include <2geom/geom.h>
17 #include "line-snapper.h"
18 #include "snapped-line.h"
19 #include <gtk/gtk.h>
21 Inkscape::LineSnapper::LineSnapper(SPNamedView const *nv, NR::Coord const d) : Snapper(nv, d)
22 {
24 }
26 void Inkscape::LineSnapper::_doFreeSnap(SnappedConstraints &sc,
27 Inkscape::Snapper::PointType const &t,
28 NR::Point const &p,
29 bool const &f,
30 std::vector<NR::Point> &points_to_snap,
31 std::list<SPItem const *> const &it) const
32 {
33 /* Get the lines that we will try to snap to */
34 const LineList lines = _getSnapLines(p);
36 // std::cout << "snap point " << p << " to: " << std::endl;
38 for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
39 NR::Point const p1 = i->second; // point at guide/grid line
40 NR::Point const p2 = p1 + NR::rot90(i->first); // 2nd point at guide/grid line
41 // std::cout << " line through " << i->second << " with normal " << i->first;
42 g_assert(i->first != NR::Point(0,0)); // we cannot project on an linesegment of zero length
44 NR::Point const p_proj = project_on_linesegment(p, p1, p2);
45 NR::Coord const dist = NR::L2(p_proj - p);
46 //Store any line that's within snapping range
47 if (dist < getSnapperTolerance()) {
48 _addSnappedLine(sc, p_proj, dist, i->first, i->second);
49 // std::cout << " -> distance = " << dist;
50 }
51 // std::cout << std::endl;
52 }
53 }
55 void Inkscape::LineSnapper::_doConstrainedSnap(SnappedConstraints &sc,
56 Inkscape::Snapper::PointType const &/*t*/,
57 NR::Point const &p,
58 bool const &/*f*/,
59 std::vector<NR::Point> &/*points_to_snap*/,
60 ConstraintLine const &c,
61 std::list<SPItem const *> const &/*it*/) const
63 {
64 /* Get the lines that we will try to snap to */
65 const LineList lines = _getSnapLines(p);
67 for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
68 if (NR::L2(c.getDirection()) > 0) { // Can't do a constrained snap without a constraint
69 /* Normal to the line we're trying to snap along */
70 NR::Point const n(NR::rot90(NR::unit_vector(c.getDirection())));
72 NR::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;
74 /* Constant term of the line we're trying to snap along */
75 NR::Coord const q0 = dot(n, point_on_line);
76 /* Constant term of the grid or guide line */
77 NR::Coord const q1 = dot(i->first, i->second);
79 /* Try to intersect this line with the target line */
80 Geom::Point t_2geom(NR_HUGE, NR_HUGE);
81 Geom::IntersectorKind const k = Geom::line_intersection(n.to_2geom(), q0, i->first.to_2geom(), q1, t_2geom);
82 NR::Point t(t_2geom);
84 if (k == Geom::intersects) {
85 const NR::Coord dist = L2(t - p);
86 if (dist < getSnapperTolerance()) {
87 // When doing a constrained snap, we're already at an intersection.
88 // This snappoint is therefore fully constrained, so there's no need
89 // to look for additional intersections; just return the snapped point
90 // and forget about the line
91 sc.points.push_back(SnappedPoint(t, dist, getSnapperTolerance(), getSnapperAlwaysSnap()));
92 }
93 }
94 }
95 }
96 }
98 /*
99 Local Variables:
100 mode:c++
101 c-file-style:"stroustrup"
102 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
103 indent-tabs-mode:nil
104 fill-column:99
105 End:
106 */
107 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :