Bar lines

[Mats Bengtsson]

Because of a question in user-lilypond, I looked at the function
scm/output-lib.scm: default-break-barline
and noticed a few problems:

This function handles a number of bar types that are not handled
by Bar_line::compound_barline(...), which is a problem since
default-break-barline is only called at line breaks.

"||:" is treated twice, whereas ":||" is missing, probably an
old copy-paste bug.

I propose to make the following change:

- Always call the function, not only at line breaks
- Let the function return three values "glyph in the middle
  of the line", "glyph at line end" and "glyph at line start".
- Revise the current list of bar types. Are the "brace" and
  "bracket" cases ever used, for example?
- Add documentation of all the bar types.


Of course, an alternative is to only handle the bar types that
are handled in Bar_line::compound_barline and let the user
redefine the break-glyph-function property of the BarLine
object if he for example wants "||" +"|:" at a line break.
However, that's a more troublesome and limited solution.

Suggestions, comments?

   /Mats


--
=============================================
        Mats Bengtsson
        Signal Processing
        Signals, Sensors and Systems
        Royal Institute of Technology
        SE-100 44  STOCKHOLM
        Sweden
        Phone: (+46) 8 790 8463                         
        Fax:   (+46) 8 790 7260
        Email: address@hidden
        WWW: http://www.s3.kth.se/~mabe
=============================================