Re: New feature: automatically invert chords or drop/rise chord notes (issue 365840043 by address@hidden)

[dak]

On 2019/01/28 20:02:53, Valentin Villenave wrote:

> I can’t figure out how to make it work without resetting the
EventChord’s
> elements list. How would you proceed?

Without any pointer to what you are having problems with, this is
essentially "do it yourself".  Sigh.  I don't even understand what those
interfaces are supposed to be good for so I at least changed the
internals to stop chaotically mixing directions and counts.  The
user-level commands remain as chaotic as I find them to be.

Try this patched-up variant of code posted in the mailing list.

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\version "2.21.0"

#(define-public (move-chord-note n octs)
   (_i "Transpose a note (numbered as @var{n}) by @var{octs} octaves.
@var{n} is zero-based and can be negative to count from the end.")
   (lambda (music)
     (define (proper-pitch note)
       (let* ((oct (ly:music-property note 'octavation))
              (pitch (ly:music-property note 'pitch)))
         (if (number? oct)
             (ly:pitch-transpose pitch (ly:make-pitch oct 0))
             pitch)))
     (if (music-is-of-type? music 'event-chord)
         (let* ((elts (extract-typed-music music 'note-event))
                (l (length elts))
                ;; if direction is up, count from the bottom note upward,
                ;; if direction is down, count from the top note downward.
                (count-from (if (negative? n) (+ l n) n))
                ;; Notes may not have been entered from bottom to top;
                ;; extract the pitches and put them in order.
                (notes (sort-list elts
                                  (lambda (a b)
                                    (ly:pitch<? (proper-pitch a) (proper-pitch 
b))))))
           (if (< -1 count-from l)
               (let* ((note (list-ref elts count-from))
                      (oct (ly:music-property note 'octavation 0)))
                 (ly:music-transpose note (ly:make-pitch octs 0))
                 (set! (ly:music-property note 'octavation) (+ oct octs))))))
     music))

dropNote =
#(define-music-function (num music) (integer? ly:music?)
   (_i "Drop a note of any chords in @var{music}, in @var{num}
position from above.")
   (music-map (move-chord-note (- num) -1) music))

raiseNote =
#(define-music-function (parser location num music) (integer? ly:music?)
   (_i "Raise a note of any chords in @var{music}, in @var{num}
position from below.")
   (music-map (move-chord-note (1- num) 1) music))

invertChords =
#(define-music-function (num music) (integer? ly:music?)
   (_i "Invert any chords in @var{music} into their @var{num}-th
position.
(Chord inversions may be directed downwards using negative integers.)")
   (let loop ((num num) (music music))
     (cond ((zero? num) music)
       ((negative? num) (loop (1+ num) (dropNote 1 music)))
       (else (loop (1- num) (raiseNote 1 music))))))


ac =
\chordmode {
  \dropNote 2 c:maj
  \raiseNote 1 d:m7
  \invertChords 2 e:m7
}

<<
  \chords { \ac }
  {
    <>^\markup \sans "(should be: C△, Dm7 and Em7)"
    \ac  \bar "||"
  }


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https://codereview.appspot.com/365840043/