src/line-snapper.cpp

   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  */
  13
  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>
  20
  21 Inkscape::LineSnapper::LineSnapper(SPNamedView const *nv, NR::Coord const d) : Snapper(nv, d)
  22 {
  23
  24 }
  25
  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);
  35
  36     // std::cout << "snap point " << p << " to: " << std::endl;
  37
  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
  43
  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 }
  54
  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
  62
  63 {
  64     /* Get the lines that we will try to snap to */
  65     const LineList lines = _getSnapLines(p);
  66
  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())));
  71
  72             NR::Point const point_on_line = c.hasPoint() ? c.getPoint() : p;
  73
  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);
  78
  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);
  83
  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 }
  97
  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 :