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) 1999-2008 Authors
10 *
11 * Released under GNU GPL, read the file 'COPYING' for more information
12 */
14 #include <2geom/line.h>
15 #include "line-snapper.h"
16 #include "snapped-line.h"
17 //#include <gtk/gtk.h>
18 #include "snap.h"
20 Inkscape::LineSnapper::LineSnapper(SnapManager *sm, Geom::Coord const d) : Snapper(sm, d)
21 {
22 }
24 void Inkscape::LineSnapper::freeSnap(SnappedConstraints &sc,
25 Inkscape::SnapPreferences::PointType const &t,
26 Geom::Point const &p,
27 SnapSourceType const &source_type,
28 bool const &/*f*/,
29 Geom::OptRect const &/*bbox_to_snap*/,
30 std::vector<SPItem const *> const */*it*/,
31 std::vector<std::pair<Geom::Point, int> > */*unselected_nodes*/) const
32 {
33 if (!(_snap_enabled && _snapmanager->snapprefs.getSnapFrom(t)) ) {
34 return;
35 }
37 /* Get the lines that we will try to snap to */
38 const LineList lines = _getSnapLines(p);
40 // std::cout << "snap point " << p << " to: " << std::endl;
42 for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
43 Geom::Point const p1 = i->second; // point at guide/grid line
44 Geom::Point const p2 = p1 + Geom::rot90(i->first); // 2nd point at guide/grid line
45 // std::cout << " line through " << i->second << " with normal " << i->first;
46 g_assert(i->first != Geom::Point(0,0)); // we cannot project on an linesegment of zero length
48 Geom::Point const p_proj = Geom::projection(p, Geom::Line(p1, p2));
49 Geom::Coord const dist = Geom::L2(p_proj - p);
50 //Store any line that's within snapping range
51 if (dist < getSnapperTolerance()) {
52 _addSnappedLine(sc, p_proj, dist, source_type, i->first, i->second);
53 // For any line that's within range, we will also look at it's "point on line" p1. For guides
54 // this point coincides with its origin; for grids this is of no use, but we cannot
55 // discern between grids and guides here
56 Geom::Coord const dist_p1 = Geom::L2(p1 - p);
57 if (dist_p1 < getSnapperTolerance()) {
58 _addSnappedLinesOrigin(sc, p1, dist_p1, source_type);
59 // Only relevant for guides; grids don't have an origin per line
60 // Therefore _addSnappedLinesOrigin() will only be implemented for guides
61 }
62 // std::cout << " -> distance = " << dist;
63 }
64 // std::cout << std::endl;
65 }
66 }
68 void Inkscape::LineSnapper::constrainedSnap(SnappedConstraints &sc,
69 Inkscape::SnapPreferences::PointType const &t,
70 Geom::Point const &p,
71 SnapSourceType const &source_type,
72 bool const &/*f*/,
73 Geom::OptRect const &/*bbox_to_snap*/,
74 ConstraintLine const &c,
75 std::vector<SPItem const *> const */*it*/) const
77 {
78 if (_snap_enabled == false || _snapmanager->snapprefs.getSnapFrom(t) == false) {
79 return;
80 }
82 /* Get the lines that we will try to snap to */
83 const LineList lines = _getSnapLines(p);
85 for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
86 if (Geom::L2(c.getDirection()) > 0) { // Can't do a constrained snap without a constraint
87 // constraint line
88 Geom::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;
89 Geom::Line line1(point_on_line, point_on_line + c.getDirection());
91 // grid/guide line
92 Geom::Point const p1 = i->second; // point at guide/grid line
93 Geom::Point const p2 = p1 + Geom::rot90(i->first); // 2nd point at guide/grid line
94 Geom::Line line2(p1, p2);
96 Geom::OptCrossing inters = Geom::OptCrossing(); // empty by default
97 try
98 {
99 inters = Geom::intersection(line1, line2);
100 }
101 catch (Geom::InfiniteSolutions e)
102 {
103 // We're probably dealing with parallel lines, so snapping doesn't make any sense here
104 continue; // jump to the next iterator in the for-loop
105 }
107 if (inters) {
108 Geom::Point t = line1.pointAt((*inters).ta);
109 const Geom::Coord dist = Geom::L2(t - p);
110 if (dist < getSnapperTolerance()) {
111 // When doing a constrained snap, we're already at an intersection.
112 // This snappoint is therefore fully constrained, so there's no need
113 // to look for additional intersections; just return the snapped point
114 // and forget about the line
115 _addSnappedPoint(sc, t, dist, source_type);
116 // For any line that's within range, we will also look at it's "point on line" p1. For guides
117 // this point coincides with its origin; for grids this is of no use, but we cannot
118 // discern between grids and guides here
119 Geom::Coord const dist_p1 = Geom::L2(p1 - p);
120 if (dist_p1 < getSnapperTolerance()) {
121 _addSnappedLinesOrigin(sc, p1, dist_p1, source_type);
122 // Only relevant for guides; grids don't have an origin per line
123 // Therefore _addSnappedLinesOrigin() will only be implemented for guides
124 }
125 }
126 }
127 }
128 }
129 }
131 // Will only be overridden in the guide-snapper class, because grid lines don't have an origin; the
132 // grid-snapper classes will use this default empty method
133 void Inkscape::LineSnapper::_addSnappedLinesOrigin(SnappedConstraints &/*sc*/, Geom::Point const /*origin*/, Geom::Coord const /*snapped_distance*/, SnapSourceType const &/*source_type*/) const
134 {
135 }
137 /*
138 Local Variables:
139 mode:c++
140 c-file-style:"stroustrup"
141 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
142 indent-tabs-mode:nil
143 fill-column:99
144 End:
145 */
146 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :