To: "David Kastrup" <[email protected]> Cc: "lilypond-user" <[email protected]> Sent: Saturday, October 12, 2013 2:29 PM Subject: Re: Piano/Xylophone key diagrams
2013/10/12 David Kastrup <[email protected]>:"Phil Holmes" <[email protected]> writes:At college, one of my ensembles is a mixed-music group performing modern music. I normally get away with singing or "playing" a triangle and bits of other untuned percussion. Imagine my surprised when I was given a xylophone piece to play. Fortunately, it's only one note at a time, and most of them are the same note, repeated for four bars, so I generally have the time to work out where the next key is when I'm playing the current one. However, I thought it might be interesting and vaguely useful to have some piano key diagrams which show which key is to be played, rather like the fingering diagrams. The attached image illustrates the kind of thing: playing D#. I know I could use box, rounded-box or filled-box, or moveto/lineto commands to draw the boxes, so I clearly could create the diagrams individually for each note. However, I thought it would be better to create a function to do this. I'd presume the location of each box would be in some sort of array/list, and that the function would use the 'pitch of the note to determine which to fill. However, I've read our documentation on scheme and am stuck on how to start, either creating the array/list and iterating over it to draw boxes, or grabbing the pitch value of a note. Could anyone start me off on this and help when I get stuck again?Starting off would be on <URL:http://code.google.com/p/lilypond/issues/detail?id=3563#c4>. Check its output. This is basically what you need, except that you need to replace the C-Griff function which uses filled and non-filled circles in a three-row arrangement with a more tedious rectangular arrangement. The c-griff function here only does the formatting and would need to be completely replaced. In contrast, the stuff in define-scheme-function could be kept unchanged.Or maybe http://lsr.dsi.unimi.it/LSR/Item?id=791 might give some inspiration. Cheers, Harm
Thanks to David and Harm for their suggestions. For now I've gone with adapting what Harm suggested - I've tidied the code a little and added a scaling parameter that varies the width of the keys and the size of the dot. Example output is attached, together with the file used to create this.
--Phil Holmes
<<attachment: Keys_new.png>>
#(define KEY-POS-LIST '(
(c . 1) (cis . 1.5) (des . 1.5) (d . 2) (dis . 2.5) (ees . 2.5) (e . 3)
(f . 4) (fis . 4.5) (ges . 4.5) (g . 5) (gis . 5.5) (aes . 5.5) (a . 6)
(ais . 6.5) (bes . 6.5) (b . 7)))
#(define (black-key? num )
(member num '(cis des dis ees fis ges gis aes ais bes)) )
#(define (key-to-pos key ypos scale)
(let ((keypos (assq key KEY-POS-LIST)))
(if (not keypos)
(ly:error (_ "keyboard diagram error - unknown note '~a'") key)
(cons (* (- (cdr (assq key KEY-POS-LIST)) 0.5) scale) (+ (* (- scale 1) 0.32) ypos)))))
#(define (make-keys l1 width off height scale)
(if (null? l1)
empty-stencil
(ly:stencil-add
(ly:stencil-translate
(make-line-stencil 0.1 0 0 0 height)
(cons (* (- (car l1) 1) scale) off ))
(make-keys (cdr l1) width off height scale))))
#(define (make-keys-black l1 width off height scale)
(if (null? l1)
empty-stencil
(ly:stencil-add
(ly:stencil-translate
(ly:round-filled-box `(0 . ,(* width scale)) `(0 . ,height) 0)
(cons (* (- (car l1) (/ width 2)) scale ) off))
(make-keys-black (cdr l1) width off height scale))))
#(define (make-dot key scale)
(if (black-key? key)
(ly:stencil-in-color
(ly:stencil-translate (make-circle-stencil (* 0.27 scale) 0 #t) (key-to-pos key 2.5 scale)) 1 1 1)
(ly:stencil-translate (make-circle-stencil (* 0.32 scale) 0 #t) (key-to-pos key 0.5 scale)) ))
#(define (make-dot-list l1 scale)
(if (null? l1)
empty-stencil
(ly:stencil-add
(make-dot (car l1) scale)
(make-dot-list (cdr l1) scale ))))
#(define-markup-command (keys layout props arg1 arg2) (list? number?)
(ly:stencil-add
(make-line-stencil 0.1 0 0 (* 7 arg2) 0)
(make-line-stencil 0.1 0 6 (* 7 arg2) 6)
(make-keys '(1 2 3 4 5 6 7 8) 1 0 6 arg2)
(make-keys-black '(1 2 4 5 6 ) 0.65 2 4 arg2)
(make-dot-list arg1 arg2)))
key_scale=2.0
\relative c'' {
\textLengthOn
b4^\markup\keys #'(b) #1 r r2 r1
b4^\markup\keys #'(b) #1.5 r r2 r1
b4^\markup\keys #'(b) #key_scale r r2 r1
a4^\markup\keys #'(a) #2.5 r r2 r1
bes4^\markup\keys #'(bes) #3 r r2
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