+MAKE_SCHEME_CALLBACK (Bar_line, calc_anchor, 1)
+SCM
+Bar_line::calc_anchor (SCM smob)
+{
+ Grob *me = unsmob_grob (smob);
+ Real kern = robust_scm2double (me->get_property ("kern"), 1);
+ Real staffline = me->layout ()->get_dimension (ly_symbol2scm ("line-thickness"));
+ string str = robust_scm2string (me->get_property ("glyph-name"), "");
+
+ /* we put the anchor in the center of the barline, unless we are
+ a repeat bar, in which case we put the anchor in the center of
+ the barline without the dots. */
+ Interval ext = me->extent (me, X_AXIS);
+ if (ext.is_empty ())
+ return scm_from_double (0);
+
+ Real anchor = ext.center ();
+
+ Stencil dot = Font_interface::get_default_font (me)->find_by_name ("dots.dot");
+ Real dot_width = dot.extent (X_AXIS).length () + kern * staffline;
+ if (str == "|:")
+ anchor -= dot_width / 2;
+ else if (str == ":|")
+ anchor += dot_width / 2;
+
+ return scm_from_double (anchor);
+}
+
+ADD_INTERFACE (Bar_line,
+ "Bar line.\n"
+ "\n"
+ "Print a special bar symbol. It replaces the regular bar"
+ " symbol with a special symbol. The argument @var{bartype}"
+ " is a string which specifies the kind of bar to print."
+ " Options are @code{:|}, @code{|:}, @code{:|:}, @code{||},"
+ " @code{|.}, @code{.|}, and @code{.|.}.\n"
+ "\n"
+ "These produce, respectively, a right repeat, a left repeat,"
+ " a double repeat, a double bar, a start bar, an end bar, and"
+ " a thick double bar. In addition, there is an option"
+ " @code{||:} which is equivalent to @code{|:} except at line"
+ " breaks, where it produces a double bar (@code{||}) at the"
+ " end of the line and a repeat sign (@code{|:}) at the"
+ " beginning of the new line.\n"
+ "\n"
+ "If @var{bartype} is set to @code{empty} then nothing is"
+ " printed, but a line break is allowed at that spot.\n"
+ "\n"
+ "@code{gap} is used for the gaps in dashed barlines.",
+
+ /* properties */
+ "allow-span-bar "
+ "gap "
+ "kern "
+ "thin-kern "
+ "hair-thickness "
+ "thick-thickness "
+ "glyph "
+ "glyph-name "
+ "bar-size "
+ "bar-extent "
+ );