2015-04-20 23:45 GMT+02:00 David Nalesnik <david.nales...@gmail.com>:
> Hi Steven,
>
> On Mon, Apr 20, 2015 at 3:40 PM, Steven Weber <pant...@hotmail.com> wrote:
>>
>> Since I always highlight clef changes in my music and I have access to a
>> color printer, I thought it’d be more efficient to let Lilypond do the
>> highlighting for me. I wrote a handy function that places a filled-box
>> behind the clef grob, and it works great, as long as I add it manually for
>> every clef change. What I really want is to add this to the Staff context
>> so I never have to think about it again. So I created an override function
>> for the Staff.Clef.stencil which does the same thing as my manual function
>> and again, it does highlight the clefs. Unfortunately, it highlights every
>> single clef (i.e., all the clefs at the beginning of the staves, not just
>> the clef changes), which is overkill and defeats the purpose of highlighting
>> things I need to pay attention to.
>>
>>
>>
>> Is there a way in scheme to say “is this grob being typeset because of an
>> explicit command (\clef bass), or implicitly (because of a line break)”?
>>
>>
>
>
> I can think of two ways to go about this. Hopefully the first gives you
> what you want, because the second will take some doing.
>
> Breakable items like clefs have directions attached depending on where they
> are: -1 means end of line, 0 unbroken, and 1 beginning of line. You can use
> the function ly:item-break-dir like so:
>
> \version "2.19"
>
> #(define highlight
> (lambda (grob)
> (let ((ibd (ly:item-break-dir grob)))
> (if (= ibd 1) black green))))
>
> {
> \override Staff.Clef.color = #highlight
>
> c' d' e' f'
> \clef bass
> c d e f
> \break
> c d e f
> \clef treble
> c' d' e' f'
> \break
> c' d' e' f'
> \clef bass
> \break
> c d e f
> }
>
>
> %%%
>
> One drawback here would be if you want to highlight both the cautionary clef
> and the beginning-of-line clef at the end of the example... To do that and
> not catch other beginning-of-line clefs, we would have to use the other
> method, which is to insert the override into the music expression.
>
> I'm going to drop out at this point :) But, as a head start, compare the
> results of running the following with the override left in or commented out:
>
> \displayMusic {
> c'
> %\override Staff.Clef.color = #highlight
> \clef bass
> c
> }
>
> The extending manual discusses this sort of manipulation with respect to
> music functions. There are other useful commands like map-some-music which
> crop up periodically on the lists.
>
> Hope this is useful--
>
> David
Or maybe:
\version "2.19.18"
clef-color-engraver =
#(lambda (context)
(let ((clef-props '()))
`((acknowledgers
(clef-interface
. ,(lambda (engraver grob source-engraver)
(let* ((clefGlyph (ly:context-property context 'clefGlyph))
(clefPosition (ly:context-property context 'clefPosition))
(clefTransposition
(ly:context-property context 'clefTransposition 0))
(new-clef-props
(list clefGlyph clefPosition clefTransposition)))
;(display (equal? clef-props new-clef-props))
(if (and (not (equal? clef-props new-clef-props))
;; to have the first clef colored as well
;; comment next line
(not (null? clef-props))
)
(set! (ly:grob-property grob 'color) red))
(set! clef-props new-clef-props))))))))
%%%%%%%%%%%%%%%
%% EXAMPLE
%%%%%%%%%%%%%%
\layout {
\context {
\Staff
\consists #clef-color-engraver
}
}
<<
{
\clef bass
R1
\break
R1
\clef alto
R1
\break
\clef "G"
R1
\clef "G_8"
R1
\break
R1
\break
R1
}
{
R1
\break
R1
R1
\break
\clef "mensural-c3"
R1
\clef "alto"
R1
\break
R1
\break
R1
}
>>
Cheers,
Harm
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