Make parallel lines

And make TODO for P2P

GCS/GCS.h

@@ -250,6 +250,9 @@ public:
     void clearByTag(int tagId, bool is_fixed_point = false);
     int addConstraint(Constraint* constr);
     void removeConstraint(Constraint* constr);
+    Constraint* get_last_constraint() {
+        return clist[clist.size() - 1];
+    }
 
     // basic constraints
     int addConstraintFixed(Point& p, int tagId = 0, bool driving = true);

GCS/Geo.cpp

@@ -143,6 +143,33 @@ Line::Line(Point _p1, Point _p2, int _tag) {
     tag = _tag;
 }
 
+void Line::set_tag(int _tag) {
+    tag = _tag;
+    p1.set_tag(_tag);
+    p2.set_tag(_tag);
+}
+
+// TODO
+bool Line::contains(QPointF pos, qreal tol) const
+{
+    double x1 = *p1.x, y1 = *p1.y;
+    double x2 = *p2.x, y2 = *p2.y;
+
+    double A = y1 - y2;
+    double B = x2 - x1;
+    double C = x1 * y2 - x2 * y1;
+    
+    try {
+        double distance = abs(A * pos.x() + B * pos.y() + C) / sqrt(A * A + B * B);
+        return distance < tol;
+    }
+    catch (...) {
+        return false;
+    }
+    
+    
+}
+
 DeriVector2 Line::CalculateNormal(const Point& p, const double* derivparam) const
 {
     (void)p;

GCS/Geo.h

@@ -227,11 +227,8 @@ public:
     Line* Copy() override;
 
     void draw(QPainter& p, bool highlight = false);
-    void set_tag(int _tag) {
-        tag = _tag;
-        p1.set_tag(_tag);
-        p2.set_tag(_tag);
-    }
+    void set_tag(int);
+    bool contains(QPointF, qreal tol = 10.0) const;
 };
 
 class Circle: public Curve