gtk/src/edge.cpp

   1 #include <cmath>
   2
   3 #include "edge.hpp"
   4
   5 Edge::Edge(Vertex &source, Vertex &target) :
   6         Drawable<Edge *>(),
   7         _source(&source),
   8         _target(&target)
   9 {
  10
  11 }
  12
  13 Edge::~Edge(void)
  14 {
  15
  16 }
  17
  18 void Edge::draw(Cairo::RefPtr<Cairo::Context> cr)
  19 {
  20         gdouble start_x, start_y;
  21         gdouble end_x, end_y;
  22
  23         if (cr) {
  24                 _source->get_bottom_anchor(start_x, start_y);
  25                 _target->get_top_anchor(end_x, end_y);
  26
  27                 cr->save();
  28                 cr->begin_new_path();
  29                 cr->move_to(start_x, start_y);
  30                 cr->line_to(end_x, end_y);
  31                 cr->set_line_width(2.0);
  32                 cr->set_line_cap(Cairo::LINE_CAP_ROUND);
  33                 cr->stroke();
  34                 cr->restore();
  35         }
  36 }
  37
  38 bool Edge::select(Cairo::RefPtr<Cairo::Context> cr, gdouble x, gdouble y)
  39 {
  40         if (!_is_in_region(cr, x, y)) {
  41                 return false;
  42         }
  43
  44         // If y-coordinate is positive, it means that it is closer to the target
  45         // sentence
  46         if (y > 0) {
  47                 change_target_follow_mouse();
  48         } else {
  49                 change_source_follow_mouse();
  50         }
  51
  52         return true;
  53 }
  54
  55 void Edge::deselect(void)
  56 {
  57
  58 }
  59
  60 void Edge::change_source(Vertex &source)
  61 {
  62
  63 }
  64
  65 void Edge::change_target(Vertex &target)
  66 {
  67
  68 }
  69
  70 void Edge::change_source_follow_mouse(void)
  71 {
  72
  73 }
  74
  75 void Edge::change_target_follow_mouse(void)
  76 {
  77
  78 }
  79
  80 bool
  81 Edge::_is_in_region(Cairo::RefPtr<Cairo::Context> cr, gdouble x, gdouble y) const
  82 {
  83         gdouble start_x, start_y;
  84         gdouble end_x, end_y;
  85         gdouble a, b, distance;
  86
  87         _source->get_bottom_anchor(start_x, start_y);
  88         _target->get_top_anchor(end_x, end_y);
  89
  90         // Discards the point if its higher than the source anchor or lower than
  91         // the target anchor
  92         if (y < start_y || y > end_y) {
  93                 return false;
  94         }
  95
  96         // The point has to be within 5 units away from the line segment
  97         a = start_x - end_x;
  98         b = start_y - end_y;
  99         distance = (fabs(a * (end_y - y) - (end_x - x) * b) /
 100                     sqrt(pow(a, 2) + pow(b, 2)));
 101         if (distance < 5.0) {
 102                 return true;
 103         }
 104
 105         return false;
 106 }