src/line-snapper.cpp

   1 #include "libnr/nr-values.h"
   2 #include "libnr/nr-point-fns.h"
   3 #include "geom.h"
   4 #include "line-snapper.h"
   5
   6 Inkscape::LineSnapper::LineSnapper(SPNamedView const *nv, NR::Coord const d) : Snapper(nv, d)
   7 {
   8
   9 }
  10
  11 Inkscape::SnappedPoint Inkscape::LineSnapper::_doFreeSnap(Inkscape::Snapper::PointType const &t,
  12                                                                                                         NR::Point const &p,
  13                                                                                                         bool const &f,
  14                                                         std::vector<NR::Point> &points_to_snap,
  15                                                     std::list<SPItem const *> const &it) const
  16 {
  17     /* Snap along x (ie to vertical lines) */
  18     Inkscape::SnappedPoint const v = _doConstrainedSnap(t, p, f, points_to_snap, component_vectors[NR::X], it);
  19     /* Snap along y (ie to horizontal lines) */
  20     Inkscape::SnappedPoint const h = _doConstrainedSnap(t, p, f, points_to_snap, component_vectors[NR::Y], it);
  21
  22     /* If we snapped to both, combine the two results.  This is so that, for example,
  23     ** we snap nicely to the intersection of two guidelines.
  24     */
  25     if (v.getDistance() < NR_HUGE && h.getDistance() < NR_HUGE) {
  26         return SnappedPoint(NR::Point(v.getPoint()[NR::X], h.getPoint()[NR::Y]), hypot(v.getDistance(), h.getDistance()));
  27     }
  28
  29     /* If we snapped to a vertical line, return that */
  30     if (v.getDistance() < NR_HUGE) {
  31         return v;
  32     }
  33
  34     /* Otherwise just return any horizontal snap; if we didn't snap to that either
  35     ** we haven't snapped to anything.
  36     */
  37     return h;
  38 }
  39
  40 Inkscape::SnappedPoint Inkscape::LineSnapper::_doConstrainedSnap(Inkscape::Snapper::PointType const &t,
  41                                                                                                         NR::Point const &p,
  42                                                     bool const &f,
  43                                                         std::vector<NR::Point> &points_to_snap,
  44                                                                 ConstraintLine const &c,
  45                                                     std::list<SPItem const *> const &it) const
  46 {
  47     Inkscape::SnappedPoint s = SnappedPoint(p, NR_HUGE);
  48
  49     /* Get the lines that we will try to snap to */
  50     const LineList lines = _getSnapLines(p);
  51
  52     for (LineList::const_iterator i = lines.begin(); i != lines.end(); i++) {
  53
  54         /* Normal to the line we're trying to snap along */
  55         NR::Point const n(NR::rot90(NR::unit_vector(c.getDirection())));
  56
  57         /* Constant term of the line we're trying to snap along */
  58         NR::Coord const q = dot(n, c.hasPoint() ? c.getPoint() : p);
  59
  60         /* Try to intersect this line with the target line */
  61         NR::Point t = p;
  62         IntersectorKind const k = intersector_line_intersection(n, q, component_vectors[i->first], i->second, t);
  63
  64         if (k == INTERSECTS) {
  65             const NR::Coord dist = L2(t - p);
  66             if (dist < getDistance() && dist < s.getDistance() ) {
  67                 s = SnappedPoint(t, dist);
  68             }
  69         }
  70     }
  71
  72     return s;
  73 }
  74
  75 /*
  76   Local Variables:
  77   mode:c++
  78   c-file-style:"stroustrup"
  79   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  80   indent-tabs-mode:nil
  81   fill-column:99
  82   End:
  83 */
  84 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :