+ *dy = rp - lp;
+ points.push_back (Offset (stems[LEFT]->relative_coordinate (commonx, X_AXIS) - x0, lp));
+ points.push_back (Offset (stems[RIGHT]->relative_coordinate (commonx, X_AXIS) - x0, rp));
+ }
+ else
+ {
+ /*
+ Use outer non-rest columns to determine slope
+ */
+ Grob *left_col = 0;
+ Grob *right_col = 0;
+ get_bounds (me, &left_col, &right_col);
+ if (left_col && right_col)
+ {
+ Interval rv = right_col->extent (commony, Y_AXIS);
+ Interval lv = left_col->extent (commony, Y_AXIS);
+ rv.unite (staff);
+ lv.unite (staff);
+ Real graphical_dy = rv[dir] - lv[dir];
+
+ Slice ls = Note_column::head_positions_interval (left_col);
+ Slice rs = Note_column::head_positions_interval (right_col);
+
+ Interval musical_dy;
+ musical_dy[UP] = rs[UP] - ls[UP];
+ musical_dy[DOWN] = rs[DOWN] - ls[DOWN];
+ if (sign (musical_dy[UP]) != sign (musical_dy[DOWN]))
+ *dy = 0.0;
+ else if (sign (graphical_dy) != sign (musical_dy[DOWN]))
+ *dy = 0.0;
+ else
+ *dy = graphical_dy;
+ }
+ else
+ *dy = 0;