Re: Automatic setting custom bar lines

[jakob lund]

13. feb. 2012 01.54 skrev Thomas Morley <address@hidden>:
> Hi again,
>
> perhaps you may want to use:
>
> \version "2.14.2"
> %\version "2.15.29"
>
> CustomDefaultBarLineEngraver =
> #(lambda (context)
>  (let ((glyph "|"))
>    `((acknowledgers
>      (bar-line-interface .
>        ,(lambda (engraver grob source-engraver)
>              (if (equal? glyph (ly:grob-property grob 'glyph))
>                (set! (ly:grob-property grob 'bar-extent) '(0 . 2))
>                #f)))))))
>
>
> \new Staff \relative c'' {
>     % If you don't want to put it in \layout use it like:
>     c1 \bar "" c1 c c \bar ":|:" \break
>     c1 c1 \bar "||" c c \bar ":|:" \break
>     \repeat volta 2 {
>     c1 c1 c c \bar ":|:" } \break
>     c1 \bar ":|S|:" c1 \bar "S" c \bar "|."
> }
>
> \layout {
>  \context {
>    \Staff
>    \consists #CustomDefaultBarLineEngraver
>  }
> }
>
> This is my very first custom-scheme-engraver. I'd appreciate if
> someone more experienced could have a look on it.


This is very nice! A while ago I was trying to shorten every _other_
bar line shorter, but couldn't figure out how to do it automatically.
With "your" technique it's easy to extract the bar number from
"context":

CustomOtherBarLineEngraver =
#(lambda (context)
 (let ((glyph "|"))
   `((acknowledgers
     (bar-line-interface .
       ,(lambda (engraver grob source-engraver)
             (let ((oddbar (remainder (ly:context-property context
'currentBarNumber) 2)))
             (if (and (eq? oddbar 0)
                      (equal? glyph (ly:grob-property grob 'glyph)))
               (set! (ly:grob-property grob 'bar-extent) '(-1 . 1))
               #f))))))))

I suppose the code could be parameterized in order to make it more
generally useful...

Cheers
Jakob.