+
+SCM
+Tie::get_control_points (SCM smob)
+{
+ Spanner*me = unsmob_spanner (smob);
+ Direction headdir = CENTER;
+ if (head (me,LEFT))
+ headdir = LEFT;
+ else if (head (me,RIGHT))
+ headdir = RIGHT;
+ else
+ {
+ programming_error ("Tie without heads.");
+ me->suicide ();
+ return SCM_UNSPECIFIED;
+ }
+
+ if (!Directional_element_interface::get (me))
+ Directional_element_interface::set (me, Tie::get_default_dir (me));
+
+ Real staff_space = Staff_symbol_referencer::staff_space (me);
+
+ Real x_gap_f = gh_scm2double (me->get_grob_property ("x-gap"));
+
+ Grob* l = me->get_bound (LEFT);
+ Grob* r = me->get_bound (RIGHT);
+
+ Grob* commonx = me->common_refpoint (l, X_AXIS);
+ commonx = me->common_refpoint (r, X_AXIS);
+
+ Real left_x;
+
+ /*
+ the tie has to be long enough to be visible, but should not go
+ through key sigs. In the 1.5 series the pref.matter - note
+ distance is fixed , so this won't be a problem anymore.
+ */
+ Real lambda = 0.9;
+
+ if (Note_head::has_interface (l))
+ left_x = l->extent (l, X_AXIS)[RIGHT] + x_gap_f;
+ else
+ left_x = l->extent (l, X_AXIS).linear_combination (lambda);
+
+
+ Real width;
+ if (Note_head::has_interface (l) && Note_head::has_interface (r))
+ {
+ width =
+ + r->extent (commonx,X_AXIS)[LEFT]
+ - l->extent (commonx, X_AXIS)[RIGHT]
+ -2 * x_gap_f;
+ }
+ else
+ {
+ if (Note_head::has_interface (l))
+ width = r->relative_coordinate (commonx, X_AXIS)
+ - l->extent (commonx, X_AXIS)[RIGHT]
+ - 2 * x_gap_f;
+ else
+ width =
+ - l->extent (commonx, X_AXIS).linear_combination (lambda)
+ + r->extent (commonx, X_AXIS)[LEFT]
+ - 2 * x_gap_f;
+ }
+
+ Direction dir = Directional_element_interface::get (me);
+
+ SCM details = me->get_grob_property ("details");
+
+ SCM lim // groetjes aan de chirurgendochter.
+ = scm_assq (ly_symbol2scm ("height-limit"),details);
+
+ Real h_inf = gh_scm2double (ly_cdr (lim)) * staff_space;
+ Real r_0 = gh_scm2double (ly_cdr (scm_assq (ly_symbol2scm ("ratio"),details)));
+
+ Bezier b = slur_shape (width, h_inf, r_0);
+
+ /*
+ I think this better, particularly for small ties. It always allows the user to move ties if
+ they seem in the wrong place
+
+ TODO: what if 2 heads have different size.
+
+ */
+
+ Real ypos = Tie::position_f (me) * staff_space/2
+ + dir * gh_scm2double (me->get_grob_property ("y-offset"));;
+
+ /*
+ Make sure we don't start on a dots
+ */
+ if (Note_head::has_interface (l) && Rhythmic_head::dots_l (l))
+ {
+ Grob* dots = Rhythmic_head::dots_l(l);
+ if(fabs (staff_space * Staff_symbol_referencer::position_f (dots) /2
+ - ypos) < 0.5)
+ {
+ ypos += 0.5 * dir ;
+ }
+ }
+
+
+ /*
+ todo: prevent ending / staffline collision.
+
+ todo: tie / stem collision
+ */
+
+ b = slur_shape (width,h_inf, r_0);
+ b.scale (1, dir);
+ b.translate (Offset (left_x, ypos));
+
+
+ /*
+ Avoid colliding of the horizontal part with stafflines.
+
+
+ TODO: redo this, heuristic is half-baken, and ties often look ugly
+ as a result.
+
+ TODO: doesn't work when on staff with even number of lines.
+ */
+ Array<Real> horizontal (b.solve_derivative (Offset (1,0)));
+ if (horizontal.size ())
+ {
+ /*
+ ugh. Doesnt work for non-horizontal curves.
+ */
+ Real y = b.curve_point (horizontal[0])[Y_AXIS];
+
+ Real ry = rint (y/staff_space) * staff_space;
+ Real diff = ry - y;
+ Real newy = y;
+
+ Real clear = staff_space * gh_scm2double (me->get_grob_property ("staffline-clearance"));
+
+ if (fabs (y) <= Staff_symbol_referencer::staff_radius (me)
+ && fabs (diff) < clear)
+ {
+ Real y1 = ry + clear;
+ Real y2 = ry - clear;
+
+ newy = (fabs (y1 - y) < fabs (y2 - y)) ? y1 : y2;
+
+ // newy = ry - 0.5 * staff_space * sign (diff) ;
+
+ /*
+ we don't want horizontal ties
+ */
+ if (fabs (newy - b.control_[0][Y_AXIS]) < 1e-2)
+ {
+ newy = newy + dir * staff_space;
+ }
+ }
+
+ Real y0 = b.control_ [0][Y_AXIS];
+ b.control_[2][Y_AXIS] =
+ b.control_[1][Y_AXIS] =
+ (b.control_[1][Y_AXIS] - y0) * ((newy - y0) / (y - y0)) + y0;
+ }
+ else
+ programming_error ("Tie is nowhere horizontal");
+
+
+
+ SCM controls = SCM_EOL;
+ for (int i= 4; i--;)
+ controls = gh_cons (ly_offset2scm (b.control_[i]), controls);
+ return controls;
+}
+
+
+MAKE_SCHEME_CALLBACK (Tie,brew_molecule,1);
+SCM
+Tie::brew_molecule (SCM smob)