true if the
Path was created using the constructor
Path(const Point& p0, const Point& p1), directly or indirectly.
See Path Reference; Constructors and Setting Functions.
Point p1(1, 1);
Point p2(2, 3);
Path q0(p0, p1);
cout << q0.get_line_switch();
q1 = q0;
cout << q1.get_line_switch();
Path q2 = p0.draw(p1);
cout << q2.get_line_switch();
Path q3("..", false, &p1, &p2, &p0, 0);
cout << q3.get_line_switch();
Path functions only work on linear
so it's necessary to be able to distinguish them from non-linear ones.
is_linear() should be enough to ensure that all of
these functions work, so I plan to make
soon. However, at the moment, it's still needed.
See Path Reference; Querying.