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) 1999-2008 Authors
  10  *
  11  * Released under GNU GPL, read the file 'COPYING' for more information
  12  */
  13
  14 #include <2geom/line.h>
  15 #include "line-snapper.h"
  16 #include "snapped-line.h"
  17 //#include <gtk/gtk.h>
  18 #include "snap.h"
  19
  20 Inkscape::LineSnapper::LineSnapper(SnapManager *sm, Geom::Coord const d) : Snapper(sm, d)
  21 {
  22 }
  23
  24 void Inkscape::LineSnapper::freeSnap(SnappedConstraints &sc,
  25                                                     Inkscape::SnapPreferences::PointType const &t,
  26                                                     Geom::Point const &p,
  27                                                     SnapSourceType const &source_type,
  28                                                     long source_num,
  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     }
  36
  37     /* Get the lines that we will try to snap to */
  38     const LineList lines = _getSnapLines(p);
  39
  40     // std::cout << "snap point " << p << " to: " << std::endl;
  41
  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
  47
  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, source_num, 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, source_num);
  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 }
  67
  68 void Inkscape::LineSnapper::constrainedSnap(SnappedConstraints &sc,
  69                                                Inkscape::SnapPreferences::PointType const &t,
  70                                                Geom::Point const &p,
  71                                                SnapSourceType const &source_type,
  72                                                long source_num,
  73                                                Geom::OptRect const &/*bbox_to_snap*/,
  74                                                ConstraintLine const &c,
  75                                                std::vector<SPItem const *> const */*it*/) const
  76
  77 {
  78     if (_snap_enabled == false || _snapmanager->snapprefs.getSnapFrom(t) == false) {
  79         return;
  80     }
  81
  82     /* Get the lines that we will try to snap to */
  83     const LineList lines = _getSnapLines(p);
  84
  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());
  90
  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);
  95
  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             }
 106
 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, source_num);
 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, source_num);
 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 }
 130
 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*/, long /*source_num*/) const
 134 {
 135 }
 136
 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 :