src/snapped-line.cpp

   1 /**
   2  *    \file src/snapped-line.cpp
   3  *    \brief SnappedLine class.
   4  *
   5  *    Authors:
   6  *      Diederik van Lierop <mail@diedenrezi.nl>
   7  *
   8  *    Released under GNU GPL, read the file 'COPYING' for more information.
   9  */
  10
  11 #include "snapped-line.h"
  12 #include <2geom/geom.h>
  13 #include "libnr/nr-values.h"
  14
  15 Inkscape::SnappedLineSegment::SnappedLineSegment(NR::Point snapped_point, NR::Coord snapped_distance, NR::Point start_point_of_line, NR::Point end_point_of_line)
  16     : _start_point_of_line(start_point_of_line), _end_point_of_line(end_point_of_line)
  17 {
  18         _distance = snapped_distance;
  19         _point = snapped_point;
  20         _at_intersection = false;
  21 }
  22
  23 Inkscape::SnappedLineSegment::SnappedLineSegment()
  24 {
  25         _start_point_of_line = NR::Point(0,0);
  26         _end_point_of_line = NR::Point(0,0);
  27         _distance = NR_HUGE;
  28         _point = NR::Point(0,0);
  29         _at_intersection = false;
  30 }
  31
  32
  33 Inkscape::SnappedLineSegment::~SnappedLineSegment()
  34 {
  35 }
  36
  37 Inkscape::SnappedPoint Inkscape::SnappedLineSegment::intersect(SnappedLineSegment const &line) const
  38 {
  39         //TODO: Diederik, implement the intersection
  40         NR::Point const intersection = NR::Point(NR_HUGE, NR_HUGE);
  41
  42         //if (result == INTERSECTS) {
  43                 /* The relevant snapped distance is the distance to the closest snapped line, not the
  44                 distance to the intersection. For example, when a box is almost aligned with a grid
  45                 in both horizontal and vertical directions, the distance to the intersection of the
  46                 grid lines will always be larger then the distance to a grid line. We will be snapping
  47                 to the closest snapped point however, so if we ever want to snap to the intersection
  48                 then the distance to it should at least be equal to the other distance, not greater
  49                 than it, as that would rule the intersection out
  50                 */
  51         NR::Coord distance = std::min(_distance, line.getDistance());
  52         //}
  53         return SnappedPoint(intersection, distance);
  54 };
  55
  56
  57
  58 Inkscape::SnappedLine::SnappedLine(NR::Point snapped_point, NR::Coord snapped_distance, NR::Point normal_to_line, NR::Point point_on_line)
  59     : _normal_to_line(normal_to_line), _point_on_line(point_on_line)
  60 {
  61         _distance = snapped_distance;
  62         _point = snapped_point;
  63         _at_intersection = false;
  64 }
  65
  66 Inkscape::SnappedLine::SnappedLine()
  67 {
  68         _normal_to_line = NR::Point(0,0);
  69         _point_on_line = NR::Point(0,0);
  70         _distance = NR_HUGE;
  71         _point = NR::Point(0,0);
  72         _at_intersection = false;
  73 }
  74
  75 Inkscape::SnappedLine::~SnappedLine()
  76 {
  77 }
  78
  79 Inkscape::SnappedPoint Inkscape::SnappedLine::intersect(SnappedLine const &line) const
  80 {
  81         // Calculate the intersection of to lines, which are both within snapping range
  82         // The point of intersection should be considered for snapping, but might be outside the snapping range
  83
  84         Geom::Point intersection_2geom(NR_HUGE, NR_HUGE);
  85         NR::Coord distance = NR_HUGE;
  86
  87     Geom::IntersectorKind result = Geom::line_intersection(getNormal().to_2geom(), getConstTerm(),
  88                                    line.getNormal().to_2geom(), line.getConstTerm(), intersection_2geom);
  89         NR::Point intersection(intersection_2geom);
  90
  91         if (result == Geom::intersects) {
  92                 /* The relevant snapped distance is the distance to the closest snapped line, not the
  93                 distance to the intersection. For example, when a box is almost aligned with a grid
  94                 in both horizontal and vertical directions, the distance to the intersection of the
  95                 grid lines will always be larger then the distance to a grid line. We will be snapping
  96                 to the closest snapped point however, so if we ever want to snap to the intersection
  97                 then the distance to it should at least be equal to the other distance, not greater
  98                 than it, as that would rule the intersection out
  99                 */
 100                 distance = std::min(_distance, line.getDistance());
 101                 //std::cout << "Intersected nicely, now getSIL distance = " << distance << std::endl;
 102         }
 103
 104     return SnappedPoint(intersection, distance, result == Geom::intersects);
 105 }
 106
 107 // search for the closest snapped line
 108 bool getClosestSL(std::list<Inkscape::SnappedLine> &list, Inkscape::SnappedLine &result)
 109 {
 110         bool success = false;
 111
 112         for (std::list<Inkscape::SnappedLine>::const_iterator i = list.begin(); i != list.end(); i++) {
 113                 if ((i == list.begin()) || (*i).getDistance() < result.getDistance()) {
 114                         result = *i;
 115                         success = true;
 116                 }
 117         }
 118
 119         return success;
 120 }
 121
 122 // search for the closest intersection of two snapped lines, which are both member of the same collection
 123 bool getClosestIntersectionSL(std::list<Inkscape::SnappedLine> &list, Inkscape::SnappedPoint &result)
 124 {
 125         bool success = false;
 126
 127         for (std::list<Inkscape::SnappedLine>::const_iterator i = list.begin(); i != list.end(); i++) {
 128                 std::list<Inkscape::SnappedLine>::const_iterator j = i;
 129                 j++;
 130                 for (; j != list.end(); j++) {
 131                         Inkscape::SnappedPoint sp = (*i).intersect(*j);
 132                         if (sp.getAtIntersection()) {
 133                                 if (!success || sp.getDistance() < result.getDistance()) {
 134                                         // !success because the first intersection cannot be compared to a previous one
 135                                         result = sp;
 136                                         success = true;
 137                                 }
 138                         }
 139                 }
 140         }
 141
 142         return success;
 143 }
 144
 145 // search for the closest intersection of two snapped lines, which are in two different collections
 146 bool getClosestIntersectionSL(std::list<Inkscape::SnappedLine> &list1, std::list<Inkscape::SnappedLine> &list2, Inkscape::SnappedPoint &result)
 147 {
 148         bool success = false;
 149
 150         for (std::list<Inkscape::SnappedLine>::const_iterator i = list1.begin(); i != list1.end(); i++) {
 151                 for (std::list<Inkscape::SnappedLine>::const_iterator j = list2.begin(); j != list2.end(); j++) {
 152                         Inkscape::SnappedPoint sp = (*i).intersect(*j);
 153                         if (sp.getAtIntersection()) {
 154                                 if (!success || sp.getDistance() < result.getDistance()) {
 155                                         // !success because the first intersection cannot be compared to a previous one
 156                                         result = sp;
 157                                         success = true;
 158                                 }
 159                         }
 160                 }
 161         }
 162
 163         return success;
 164 }
 165
 166 /*
 167   Local Variables:
 168   mode:c++
 169   c-file-style:"stroustrup"
 170   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 171   indent-tabs-mode:nil
 172   fill-column:99
 173   End:
 174 */
 175 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :