input/lsr/transposing-pitches-with-minimum-accidentals-smart-transpose.ly

   1 %% Do not edit this file; it is auto-generated from input/new
   2 %% This file is in the public domain.
   3 \version "2.11.57"
   4 \header {
   5 doctitlees = "Transportar música con el menor número de alteraciones"
   6 texidoces = "
   7 Este ejemplo utiliza código de Scheme para forzar las
   8 modificaciones enarmónicas de las notas, y así tener el menor
   9 número de alteraciones accidentales. En este caso se aplican las
  10 siguientes reglas:
  11
  12 @itemize
  13 @item
  14 Se quitan las dobles alteraciones
  15
  16 @item
  17 Si sostenido -> Do
  18
  19 @item
  20 Mi sistenido -> Fa
  21
  22 @item
  23 Do bemol -> Si
  24
  25 @item
  26 Fa bemol -> Mi
  27
  28 @end itemize
  29
  30 De esta forma se selecciona el mayor número de notas enarmónicas
  31 naturales.
  32
  33 "
  34   lsrtags = "pitches"
  35   texidoc = "This example uses some Scheme code to enforce enharmonic
  36 modifications for notes in order to have the minimum number of
  37 accidentals.  In this case, the following rules apply:
  38
  39 @itemize
  40 @item
  41 Double accidentals should be removed
  42
  43 @item
  44 B sharp -> C
  45
  46 @item
  47 E sharp -> F
  48
  49 @item
  50 C flat -> B
  51
  52 @item
  53 F flat -> E
  54
  55 @end itemize
  56
  57 In this manner, the most natural enharmonic notes are chosen.
  58 "
  59   doctitle = "Transposing music with minimum accidentals"
  60 } % begin verbatim
  61
  62 #(define  (naturalize-pitch p)
  63   (let* ((o (ly:pitch-octave p))
  64          (a (* 4 (ly:pitch-alteration p)))
  65     ; alteration, a, in quarter tone steps, for historical reasons
  66          (n (ly:pitch-notename p)))
  67     (cond
  68      ((and (> a 1) (or (eq? n 6) (eq? n 2)))
  69       (set! a (- a 2))
  70       (set! n (+ n 1)))
  71      ((and (< a -1) (or (eq? n 0) (eq? n 3)))
  72       (set! a (+ a 2))
  73       (set! n (- n 1))))
  74     (cond
  75      ((> a 2) (set! a (- a 4)) (set! n (+ n 1)))
  76      ((< a -2) (set! a (+ a 4)) (set! n (- n 1))))
  77     (if (< n 0) (begin (set! o (- o 1)) (set! n (+ n 7))))
  78     (if (> n 6) (begin (set! o (+ o 1)) (set! n (- n 7))))
  79     (ly:make-pitch o n (/ a 4))))
  80
  81 #(define (naturalize music)
  82   (let* ((es (ly:music-property music 'elements))
  83          (e (ly:music-property music 'element))
  84          (p (ly:music-property music 'pitch)))
  85     (if (pair? es)
  86         (ly:music-set-property!
  87          music 'elements
  88          (map (lambda (x) (naturalize x)) es)))
  89     (if (ly:music? e)
  90         (ly:music-set-property!
  91          music 'element
  92          (naturalize e)))
  93     (if (ly:pitch? p)
  94         (begin
  95           (set! p (naturalize-pitch p))
  96           (ly:music-set-property! music 'pitch p)))
  97     music))
  98
  99 naturalizeMusic =
 100 #(define-music-function (parser location m)
 101                                         (ly:music?)
 102                         (naturalize m))
 103
 104 music = \relative c' { c4 d e g }
 105
 106 \score {
 107   \new Staff {
 108     \transpose c ais \music
 109     \naturalizeMusic \transpose c ais \music
 110     \transpose c deses \music
 111     \naturalizeMusic \transpose c deses \music
 112   }
 113   \layout { }
 114 }