Re: Metronome marks

[Neil Puttock]

Hi Alexander,

On 11/04/2008, Alexander Kobel <address@hidden> wrote:

>  I think there's another drawback of the snippet.
>  I had a very similar problem, trying to add marks like "Moderato (* =
>  63)", yet using rehearsal marks at the same time for sectioning the piece.
>  Problem is, Lily can't handle two RehearsalMark events on the same beat
>  (don't know whether there's a workaround), so I wanted to use
>  MetronomeMarks. Here's my snippet to do so; I suspect it should be
>  fairly straightforward to modify to mimic the rhythmMark behaviour.

I hope you don't mind, but I've added your snippet to the LSR as
"Adding a text indication to metronome marks". Unfortunately, it
doesn't work under 2.10, so it's waiting for LSR to move to 2.11 (and
the nod from Valentin to approve it).

>  Of course it would be nice if the \tempo command would be run directly
>  in \tempoChangeMarkup; however I'm running into type problems here.
>  Is it possible to convert string->duration via Scheme? Else I always had
>  to type
>         \tempoChangeMarkup #"foo" #(make-duration 4) #"120"
>  or am I wrong there?

There's a function in define-markup-commands.scm called
parse-simple-duration which will convert a duration string to a list.
You can then just use ly:make-duration to turn the list elements into
a duration:

#(use-modules (ice-9 regex))
#(define (parse-simple-duration duration-string)
  "Parse the `duration-string', e.g. ''4..'' or ''breve.'', and return
a (log dots) list."
  (let ((match (regexp-exec (make-regexp
"(breve|longa|maxima|[0-9]+)(\\.*)") duration-string)))
    (if (and match (string=? duration-string (match:substring match 0)))
        (let ((len  (match:substring match 1))
              (dots (match:substring match 2)))
          (list (cond ((string=? len "breve") -1)
                      ((string=? len "longa") -2)
                      ((string=? len "maxima") -3)
                      (else (log2 (string->number len))))
                (if dots (string-length dots) 0)))
        (ly:error (_ "not a valid duration string: ~a") duration-string))))

#(define (string-to-duration duration)
  (let ((parsed (parse-simple-duration duration)))
  (ly:make-duration (car parsed) (cadr parsed)))
 )

I think the main problem is how to set tempoWholesPerMinute, unless
you're not bothered about MIDI output.

Regards,
Neil